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Wyświetlanie 1-35 z 35
Tytuł:
Phase Structure and Magnetic Properties of Intermetallic Cu-Ni Alloy Nanopowders Synthesized by the Electrical Explosion of Wire
Autorzy:
Nguyen, Minh-Thuyet
Kim, Jin-Chun
Powiązania:
https://bibliotekanauki.pl/articles/352297.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Cu-Ni alloy
nanoparticle
phase structure
magnetism
explosion of wire
Opis:
Cu-Ni composite nanoparticles were successfully synthesized by electrical explosion of wire (EEW) method. Cu-Ni alloy and twisted wires with various Ni contents were used as the feeding material for a 3 kV charging voltage EEW machine in an ethanol ambient chamber. The phase structure and magnetic properties of the as-fabricated samples were studied. It was established that the prepared powders after drying have a spherical form with the particle size is under 100 nm. XRD analysis indicated that the nanopowders consisted of binary Cu-Ni phases. Only pure phases of the intermetallic compound Cu-Ni (Cu0.81Ni0.19 and Cu3.8Ni) were observed in the XRD patterns of the samples. The synthesized intermetallic Cu-Ni alloy nanopowders reveal magnetic behaviors, however, the lower Ni content samples exhibited paramagnetic behaviors, meanwhile, the higher Ni content samples exposed ferromagnetic properties.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 893-898
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improving Sound Transmission Through Triple-Panel Structure Using Porous Material and Sonic Crystal
Autorzy:
Kim, Myong-Jin
Powiązania:
https://bibliotekanauki.pl/articles/177186.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
sound transmission loss
sonic crystal
triple-panel structure
sound insulation
Opis:
Main aim of this study is to combine the characteristics of the sonic crystal (SC) with acoustic panels and porous materials to improve the sound transmission loss (STL) through the triple-panel structure. SCs cause a bandgap centered around a certain frequency (Bragg’s frequency) due to generation of destructive interference. Initially, an analytical method is developed that extends the previous theory of double-panel structure to predict STL through a triple-panel structure. Finite element (FE) simulations are performer to obtain the STL through the triple-panel, which are validated with the analytical predictions. Various configurations are analyzed using the FE method based on the method of inserting the porous material and SCs between the panels to address the combined effect. STL through the triple-panel structure is compared with that through the double-panel structure having the same total weight and total thickness. It is found that the combined structure of the triple panel and the SC with glass wool as filler gives the best soundproof performance for the same external dimensions. For narrow air gaps, filing with glass wool is more advantageous than inserting one row of SC. In addition, the triple panel combined with a SC has better soundproofing than the two-panel counterparts.
Źródło:
Archives of Acoustics; 2019, 44, 3; 533-541
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relationship Between the Sound Transmission Through the Finite Double-Panel Structure with a Cylindrical Shell Array and the Vibro-Acoustic Characteristics of its Constituents
Autorzy:
Kim, Song-Hun
Kim, Myong-Jin
Powiązania:
https://bibliotekanauki.pl/articles/31339804.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
sound transmission loss
double-panel structure
eigenmode vibration
sonic crystal
Opis:
Sound insulation of the finite double-panel structure (DPS) inserted with a cylindrical shell array is investigated by varying the sound incidence direction to improve its applicability. The effects of the vibro-acoustic characteristics of its constituents on the sound transmission loss (STL) are estimated in one-third octave bands from 20 Hz to 5 kHz for different incidence conditions. It shows that the first acoustic mode in the direction parallel to two panels (longitudinal modes) produces both the sudden variation of sound insulation with frequency and a large dependency on the incidence angle. Mineral wools are placed on two boundaries perpendicular to the panels, and the sound insulation is explored for different thicknesses of the porous materials. An absorbent layer with a certain thickness (more than 30 mm in our work) sufficiently eliminates the longitudinal mode, resulting in the improvement in the sound insulation by more than 15 dB and the decrease of its large variation with incidence direction. STLs with varying shell thicknesses are also assessed. It shows that the natural vibrations of the thin shells can give an enhancement in sound insulation by more than 10 dB in the frequency range of 1600–3700 Hz, corresponding to constructive interference.
Źródło:
Archives of Acoustics; 2023, 48, 3; 381-388
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress Corrosion Cracking Properties of Steam Generator Tubing Alloys in Crevice Environment
Autorzy:
Shin, Jung-Ho
Kim, Dong-Jin
Powiązania:
https://bibliotekanauki.pl/articles/351858.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stress corrosion
nickel base alloy
nuclear plants
secondary side
passive film
Opis:
The safe and reliable operation of pressurized water reactors (PWRs) depends on the integrity of structural material. In particular, the failure of steam generator (SG) tubes on the secondary side is one of the major concerns of operating nuclear power plants. To establish remediation techniques and manage damage, it is necessary to articulate the mechanism through which various impurities affect the SG tubes. This research aims to understand the effect of impurities (e. g., S, Pb, and Cl) on the stress corrosion cracking of Alloy 600 and 690.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 543-545
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth and Characterization of Indium-Doped Zinc Oxide Thin Films Prepared by Sol-Gel Method
Autorzy:
Kim, M.
Yim, K.
Kim, S.
Nam, G.
Lee, D.
Kim, Jin
Kim, Jong
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1491351.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Dz
81.20.Fw
78.66.Hf
Opis:
Indium-doped ZnO thin films were deposited by sol-gel spin-coating method with various In content. The effects of In content on the structural and optical properties of the indium-doped ZnO thin films were investigated by scanning electron microscopy, X-ray diffraction, and UV-visible spectroscopy. The particle-like surface morphology and the crystallinity of the indium-doped ZnO thin films were affected by change in the In content, especially at the In content of 3 at.%. The values of direct band gap were decreased with increase in the In content. The width of localized states in the optical band gap of the indium-doped ZnO thin films were changed with In content and the Urbach energy $(E_{U})$ was changed inversely with optical band gap of the indium-doped ZnO thin films.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 217-220
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ZnO Nanorods on Nanofibrous ZnO Seed Layers by Hydrothermal Method and Their Annealing Effects
Autorzy:
Yim, K.
Jeon, S.
Kim, M.
Kim, S.
Nam, G.
Lee, D.
Kim, Jin
Kim, Jong
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1491348.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Dz
81.15.Lm
78.55.Et
Opis:
ZnO nanorods were grown by using the hydrothermal method on p-type Si (100) substrates with nanofibrous ZnO seed layers. Before the ZnO nanorods growth, nanofibrous ZnO seed layers were spin-coated onto the Si substrates. The structural and optical properties of ZnO nanorods were characterized by scanning electron microscopy, X-ray diffraction, and photoluminescence. The fibrous ZnO nanorods is possible due to the surface morphology of the nanofibrous ZnO seed layers. To investigate annealing effects of the ZnO nanorods, the post-annealing process was carried out at various temperatures ranging from 300 to 700C under argon conditions. The structural and optical properties of the ZnO nanorods were also affected by the post-annealing treatment.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 214-216
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Post-Heat Treatment on the Impact Toughness and Crack Propagation Mechanism of AISI D2 Tool Steel Manufactured by Direct Energy Deposition
Autorzy:
Park, Jun-Hyung
Kim, Kyu-Sik
Koo, Yong-Mo
Kim, Jin-Young
Kim, Min-Chul
Lee, Kee-Ahn
Powiązania:
https://bibliotekanauki.pl/articles/2203722.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
AISI D2 tool steel
direct energy deposition
post-heat treatment
impact toughness
fractography
Opis:
This study investigated the effect of heat treatment on the microstructure and impact toughness property of AISI D2 manufactured with direct energy deposition (DED) and compared the results with conventional wrought material. The fracture crack propagation behavior was examined in connection with microstructures through fracture surface analysis. AISI D2 manufactured with DED had a eutectic structure that turned into a net-type carbide after heat treatment, and Cr-rich needle-type secondary carbide was observed. Impact toughness of DED AISI D2 measured 2.0 J/cm2 in the as-built sample and 1.1 J/cm2 in the heat-treated sample. Compared to a wrought heat-treated AISI D2, DED AISI D2 had relatively low impact toughness. DED AISI D2 and wrought material had different crack propagation mechanisms. In DED AISI D2, the eutectic structure and net-type carbide boundary were identified as the major microstructural factor decreasing impact toughness.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 119--122
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Improved MSA Model for Evaluating the Sound Transmission Loss of a Rectangular Plate for Diffuse Field Incidence
Autorzy:
Kim, Myong-Jin
Won, Kyong-Su
Ri, Chol-Su
Powiązania:
https://bibliotekanauki.pl/articles/176309.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
transmission loss
low frequency range
natural vibration mode
diffuse field incidence
Opis:
This paper presents an approximate analytical model for estimating the transmission loss (TL) of a finite rectangular plate in the low frequency range, which is based on the modal summation approach (MSA) taking into account the modal radiation impedance and fluid loading. The mode-dependent radiation resistance is calculated using the Rayleigh integral. The fluid loading is taken into account through the natural frequency modified by the added mass. The results are compared with the ones of Statistical Energy Analysis (SEA) coupled with FEM and FEM coupled with BEM. In addition, the effects of the various vibration modes and the fluid loading on TL, and a way for reducing the calculation time are discussed.
Źródło:
Archives of Acoustics; 2019, 44, 2; 259-265
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Broadening Low-Frequency Band Gap of Double-Panel Structure Using Locally Resonant Sonic Crystal Comprised of Slot-Type Helmholtz Resonators
Autorzy:
Kim, Myong-Jin
Rim, Chun-Gil
Won, Kyong-Su
Powiązania:
https://bibliotekanauki.pl/articles/1953478.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
sound transmission loss
locally resonant sonic crystal
double-panel structure
sound insulation
Opis:
An approach is presented to form and broaden the low-frequency band gap of the double panel structure (DPS) by using a locally resonant sonic crystal (LRSC) in this work. The LRSC is made of cylindrical Helmholtz resonators arranged on square lattice. Their designs are similar to a slot-type resonator, but have different depths of slot. Elongating the slit neck inward and distributing the depths of slots produce a broad local resonant band gap at low frequencies: an average insertion loss (IL) of 10.9 dB covering 520 Hz to 1160 Hz with a LRSC of 12 cm width. Next, the effect of porous material filled into the resonators on the local resonant band gap is evaluated. It is shown that filling of porous material into the resonators decreases the height and width of the local resonant band gap. Finally, the transmission losses (TLs) through the DPS with LRSC are calculated as a function of the incident angle of the sound wave for LRSC embedded in porous material and not. The results show that the porous material can be significantly reduce the incident angle dependency of TL through the DPS with LRSC.
Źródło:
Archives of Acoustics; 2021, 46, 2; 335-340
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of Sound Insulation Through Double-Panel Structure by Using Hybrid Local Resonator Array
Autorzy:
Ri, Kyong-Su
Kim, Myong-Jin
Son-U, Se-Hyon
Powiązania:
https://bibliotekanauki.pl/articles/31339917.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
sound insulation
local resonance
insertion loss
sonic crystal
Opis:
In this paper, we present one approach to improve the soundproofing performance of the double-panel structure (DPS) in the entire audible frequencies, in which two kinds of local resonances, the breathing-type resonance and the Helmholtz resonance, are combined. The thin ring resonator row and slit-type resonator (Helmholtz resonator) row are inserted between two panels of DPS together. Overlapping of the band gaps due to the individual resonances gives a wide and high band gap of sound transmission in the low frequency range. At the same time, the Bragg-type band gap is created by the structural periodicity of the scatterers in the high audible frequency range. In addition, the number of scatterer rows and the filling factor are investigated with regard to the sound insulation of DPS with sonic crystals (SCs). Consequently, the hybrid SC has the potential of increasing the soundproofing performance of DPS in the audible frequency range above 1 kHz by about 15 dB on average compared to DPS filled only with glass wool between two panels, while decreasing the total thickness and mass compared to the counterparts with the other type of local resonant sonic crystal.
Źródło:
Archives of Acoustics; 2023, 48, 1; 63-70
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of Pure Ti Implants Fabricated by Additive Manufacturing
Autorzy:
Kim, Dong-Jin
Kim, Hyung-Giun
Kim, Ji-Sun
Song, Kuk-Hyun
Powiązania:
https://bibliotekanauki.pl/articles/354362.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pure Ti
selected laser melting
heat input
microstructure
mechanical property
Opis:
This study was carried out to evaluate the aspect of microstructure and mechanical property development on additive manufactured pure Ti at elevated heat-input. For this work, pure Ti powder (commercial purity, grade 1) was selected, and selective laser melting was conducted from 0.5 to 1.4 J/mm. As a result, increase in heat-input led to the significant grain growth form 4 μm to 12 μm, accompanying with the change of grain shape, correctly widmanstätten structured grains. In addition, Vickers microhardness was notably increased from 228 Hv to 358 Hv in accordance with elevated heat-input, which was attributed to the increased concentration of oxygen and nitrogen mainly occurred during selected laser melting process.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 959-962
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer
Autorzy:
Kim, M.
Jin, S.
Choi, H.
Kim, G.
Yim, K.
Kim, S.
Nam, G.
Yoon, H.
Kim, Y.
Lee, D.
Kim, Jin
Kim, Jong
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1505152.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
81.15.Gh
Opis:
A heavily Si-doped GaN/polymer hybrid structure with p-type poly(3,4-ethylene-dioxythiophene):beta-1,3-glucan (PEDOT nanoparticle) interface layer has been fabricated. The Si-doped GaN thin film with carrier concentration of 1 × $10^{19} cm^{-3}$ was grown by metal-organic chemical vapor deposition. The PEDOT nanoparticle with various sizes ranging from 60 to 120 nm was synthesized via a miniemulsion polymerization process. The electrical conductivity of the PEDOT nanoparticle is less than 1.2 S/cm. The current-voltage (I-V) characteristic of the hybrid structure shows diode-like behavior. The I-V characteristic was examined in the framework of the thermionic emission model. The ideality factor of the structure without PEDOT nanoparticle interface layer is 12.9. However, the ideality factor of the hybrid structure with PEDOT nanoparticle interface layer is obtained as 1.9. The value of ideality factor is dramatically decreased by inserting the PEDOT nanoparticle interface layer.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 875-879
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Atmospheric-Pressure Gas-Plasma Treatment on Surface Properties of Hot-Dip Zn-Mg-Al Alloy-Coated Steel
Autorzy:
Jeong, Chang-U
Kim, Jae-Hyeon
Park, Je-Shin
Kim, Min-Su
Kim, Sung-Jin
Oh, Min-Suk
Powiązania:
https://bibliotekanauki.pl/articles/2203736.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
plasma treatment
Zn-Mg-Al-galvanized steel
surface energy
process gas
Opis:
The effect of plasma-radical change on the surface properties of Zn-Mg-Al ternary-alloy-coated steel sheets during atmospheric-pressure (AP) plasma treatment using different process gases: O2, N2, and compressed air was investigated. The plasma-induced radicals promoted the formation of chemical particles on the surface of the Zn-Mg-Al coating, thereby increasing the surface roughness. The surface energy was calculated using the Owen-Wendt geometric equation. Contact angle measurements indicated that the surface free energy of the alloy sheets increased upon AP plasma treatment. The surface properties of the Zn-Mg-Al coating changed more significantly in the order air > O2 > N2 gas, indicating that the plasma radicals facilitated the carbonization and hydroxylation of the Mg and Al components during the AP plasma treatment.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 187--190
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dual Speed Laser Remelting for High Densification in H13 Tool Steel Metal 3D Printing
Autorzy:
Jung, Im Doo
Choe, Jungho
Yun, Jaecheol
Yang, Sangsun
Yang, Dong-Yeol
Kim, Yong-Jin
Yu, Ji-Hun
Powiązania:
https://bibliotekanauki.pl/articles/353737.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
metal 3d printing
powder bed fusion
selective laser melting
H13 tool steel
remelting
Opis:
The densification behavior of H13 tool steel powder by dual speed laser scanning strategy have been characterized for selective laser melting process, one of powder bed fusion based metal 3d printing. Under limited given laser power, the laser re-melting increases the relative density and hardness of H13 tool steel with closing pores. The single melt-pool analysis shows that the pores are located on top area of melt pool when the scanning speed is over 400 mm/s while the low scanning speed of 200 mm/s generates pores beneath the melt pool in the form of keyhole mode with the high energy input from the laser. With the second laser scanning, the pores on top area of melt pools are efficiently closed with proper dual combination of scan speed. However pores located beneath the melt pools could not be removed by second laser scanning. When each layer of 3d printing are re-melted, the relative density and hardness are improved for most dual combination of scanning. Among the scan speed combination, the 600 mm/s by 400 mm/s leads to the highest relative density, 99.94% with hardness of 53.5 HRC. This densification characterization with H13 tool steel laser re-melting can be efficiently applied for tool steel component manufacturing via metal 3d printing.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 571-578
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Study on the Electrical and Mechanical Characteristics of Ni-30wt%Co and Cu-2wt%Be Alloy for Development of Semiconductor Test Probe Pin
Autorzy:
Park, Jin-Young
Kim, Young-Choon
Kim, Jae-Gyun
Powiązania:
https://bibliotekanauki.pl/articles/353264.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
probe pin
Be-Cu Alloy
Ni-Co Alloy
test socket
mechanical properties
electrical properties
Opis:
Ultra-precision testing is a very important procedure to secure the reliability of the products as well as for the technology development in the areas of semiconductor and display. Accordingly, companies manufacturing equipment for testing of semiconductor and display have been continuously executing researches for the improvement of the performances of test sockets used in test equipment. Through this study, characteristics of the materials in accordance with the mechanical and electrical properties of Ni-30wt%Co alloy and newly developed Cu-2wt%Be alloy were analyzed in order to select the probe pin material of the socket, which is a key component used in the semiconductor testing equipment. In addition, finite element interpretation was executed by using Ansys Workbench 14.0 to comparatively analyze the finite element interpretation results and experimental results. Experiment was executed for the mechanical properties including tensile strength, elasticity modulus, specific heat, thermal expansion coefficient and Contact Force, for electrical properties, experiment on surface resistance, specific resistance and electrical conductivity was executed to measure the properties. It was confirmed that the results of finite element interpretation and experiment displayed similar trend and it is deemed that the Contact Force value was superior for Be-Co alloy. Through this study, it was confirmed that the newly developed Be-Co alloy is more appropriate as probe pin material used as the core component of test socket used in the semiconductor testing equipment than the existing Ni-Co alloy.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 943-947
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New Measures to Improve Korean Culture Education for Chinese Students in South Korea: Focusing on Racial Differences
Autorzy:
Kim, Yongdeog
Nam, Jong-ho
Moon, Hyoung-Jin
Powiązania:
https://bibliotekanauki.pl/articles/1997568.pdf
Data publikacji:
2017-12-31
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Chinese students
culture knowledge
culture teaching methods
Korean culture
Opis:
To derive a more effective educational method, racial differences among Chinese students in learning Korean culture was invesigated using a survey method. The Han and Joseon racial groups in China were examined. Before the survey, the Han race students (Chinese students except Joseon race students, in this case) preferred a language and culture teaching method (LCTM), whereas the Joseon race students favored an audiovisual teaching method (AVTM). However, after experiencing four different teaching methods – comparative-cultural teaching method (CCTM), AVTM, LCTM, and rote memorization teaching method—for two weeks, the Han race students preferred the AVTM more, whereas the Joseon race students preferred the CCTM. Thus, students from the same country require different education methods.
Źródło:
The New Educational Review; 2017, 50; 146-158
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of Analcime Zeolite Using Al and Si from Waste Resources for the Removal of Pb/Cd Ions from Aqueous Solution
Autorzy:
Kang, Yubin
Im, Byoungyong
Choi, Jin-Ju
Yoon, Jin-Ho
Kim, Dae-Guen
Powiązania:
https://bibliotekanauki.pl/articles/2048875.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
zeolite
analcime
waste resources
recycling
heavy metal removal
Opis:
Zeolites, minerals with the formula Mx/n[AlO2]x(SiO2)y] zH2O, are environmentally friendly materials used as water treatment adsorbents, gas adsorbents, and petrochemical catalysts. This study used a mixture of aluminum black dross and waste glass to synthesize zeolites via a hydrothermal synthesis and analyzed the effects of varying reaction time on phase changes under different synthesis conditions. With increased reaction times, a phase change from zeolite Na-P1 to analcime was observed; on employing hydrothermal synthesis at 150°C for 96 h, the majority of the crystalline structures changed into analcime. Heavy metal cation adsorption was tested to assess the applicability of the synthesized analcime to water treatment. Zeolite adsorption of at least 95% was observed for both Pd and Cd ions. Although a higher level of adsorption was observed for Pb ion than Cd ion, Cd ion was demonstrated to undergo relatively faster adsorption when tested under optimal pulp density at the same level of adsorption (95%).
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 67-72
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New Measures for the Improvement of History Education for Chinese Students in South Korea
Autorzy:
Hyoung-jin, Moon
Jong-ho, Nam
Yong-deog, Kim
Powiązania:
https://bibliotekanauki.pl/articles/2031731.pdf
Data publikacji:
2014-09-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Chinese students
history knowledge
history teaching methods
Korean history
Opis:
The objective of this research was to find a more effective method for the teaching of history to Chinese students studying in South Korean universities. Questionnaire surveys and interviews were conducted to investigate those students’ level of knowledge and perceptions of Korean history. Then, in history classes, four teaching methods (comparative-historical, audiovisual, history and language, and rote memorization) were applied over two weeks. Before the treatment, Chinese students said that they liked the audiovisual teaching method the most, but after taking the classes, they preferred the teaching method comparing Korean and Chinese histories. Besides the finding that the comparative method was the most popular, the responses also showed that it was the most effective one in teaching history to Chinese students.
Źródło:
The New Educational Review; 2014, 37; 54-65
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Study on Korean History Education Plans for Children from Mixed Marriages in Korea : Focus on Korean-Vietnamese, -Chinese, and -Japanese Children
Autorzy:
Moon, Hyoung-Jin
Nam, Jong-ho
Kim, Jong-suck
Powiązania:
https://bibliotekanauki.pl/articles/2140592.pdf
Data publikacji:
2022-09-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Children from mixed marriages
Korean history
history education
comparative-history teaching method
audio-visual teaching method
Opis:
This study aims to prepare the most effective Korean history education plan for children from mixed marriages in Korea using a questionnaire survey and in-depth interviews. Before the survey, the children from mixed marriages between Korea and Vietnam, China, and Japan preferred the auto-visual teaching method (ATM). However, after learning Cramming Teaching Method (CTM), Audio-Visual Teaching Method (ATM), Comparative-History Teaching Method (CHTM), and Discussion Teaching Method (DTM) for one week, Chinese and Korean – Japanese children preferred CHTM, whereas Korean-Vietnamese children preferred ATM itself. Hence, CHTM was found to be the most effective method when educating Korean history to the children from mixed marriages between Korea and countries with many historical conflicts, similar to that of their mothers (first-generation immigrants).
Źródło:
The New Educational Review; 2022, 69; 39-50
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Carbon Content on Austenite Stability and Strain-induced Transformation of Nanocrystalline FeNiC Alloy by Spark Plasma Sintering
Autorzy:
Oh, Seung-Jin
Kim, Byoung-Cheol
Suh, Man-Chul
Shon, In-Jin
Lee, Seok-Jae
Powiązania:
https://bibliotekanauki.pl/articles/355534.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
FeNiC alloy
austenite stability
strain-induced transformation
spark plasma sintering
Opis:
The effects of carbon content on the austenite stability and strain-induced transformation of nanocrystalline Fe-11%Ni alloys were investigated using X-ray analysis and mechanical tests. The nanocrystalline FeNiC alloy samples were rapidly fabricated using spark plasma sintering because of the extremely short densification time, which not only helped attain the theoretical density value but also prevented grain growth. The increased austenite stability resulted from nanosized crystallites in the sintered alloys. Increasing compressive deformation increased the volume fraction of strain-induced martensite from austenite decomposition. The kinetics of the strain-induced martensite formation were evaluated using an empirical equation considering the austenite stability factor. As the carbon content increased, the austenite stability was enhanced, contributing to not only a higher volume fraction of austenite after sintering, but also to the suppression of its strain-induced martensite transformation.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 863-867
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wave Absorption Property of High Entropy Alloy Fabricated by Sol-Gel Process
Autorzy:
Yang, Suwon
Kim, Jeong-Gon
Jeong, Kwang-Pil
Choi, Jin-Hyuk
Powiązania:
https://bibliotekanauki.pl/articles/352432.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high entropy alloy
wave absorption property
Opis:
In this study, the magnetic properties and wave absorption characteristics of high entropy alloys are investigated. The high entropy alloys with FeNiMnCoCu, FeNiMnZnCo, and FeNiZnCoCu compositions were synthesized by the sol-gel method. After the sol-gel process, the annealing process and hydrogen reduction process was performed. FeNiMnCoCu and FeNiZnCoCu were revealed soft magnetic property. The saturation magnetization was 12 emu/g and 36 emu/g, respectively. And The coercive force was –45 Oe and –34 Oe, respectively. The high entropy alloy with these compositions was revealed wave absorption property at above 10 gigahertz frequency region. And it has shown the trend that wave absorption frequency has decreased with the sample thickness increasing.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1277-1280
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural Evolution of AlCuFeMnTi-0.75Si High Entropy Alloy Processed by Mechanical Alloying and Spark Plasma Sintering
Autorzy:
Kim, Minsu
Sharma, Ashutosh
Chae, Myoung Jin
Lee, Hansung
Ahn, Byungmin
Powiązania:
https://bibliotekanauki.pl/articles/2049226.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high entropy alloy
powder metallurgy
mechanical alloying
spark plasma sintering
high energy ball milling
Opis:
In this work, we have designed a new high entropy alloy containing lightweight elements, e.g., Al, Fe, Mn, Ti, Cu, Si by high energy ball milling and spark plasma sintering. The composition of Si was kept at 0.75 at% in this study. The results showed that the produced AlCuFeMnTiSi0.75 high entropy alloy was BCC structured. The evolution of BCC1 and BCC2 phases was observed with increasing the milling time up to 60 h. The spark plasma sintering treatment of milled compacts from 650-950°C showed the phase separation of BCC into BCC1 and BCC2. The density and strength of these developed high entropy alloys (95-98%, and 1000 HV) improved with milling time and were maximum at 850°C sintering temperature. The current work demonstrated desirable possibilities of Al-Si based high entropy alloys for substitution of traditional cast components at intermediate temperature applications.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 3; 703-707
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microzooplankton in a Warming Arctic: A Comparison of Tintinnids and Radiolarians from Summer 2011 and 2012 in the Chukchi Sea
Autorzy:
Dolan, John R.
Yang, Eun Jin
Kim, Tae Wan
Kang, Sung-Ho
Powiązania:
https://bibliotekanauki.pl/articles/763780.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Tematy:
Climate change, plankton, rhizaria, sea ice, Tintinnina
Opis:
The Chukchi Sea was sampled in August of 2011, a year of near-normal sea ice among recent years, and again in August 2012, a year of all time record low sea ice. We exploited this sampling to test the hypothesis that different sea ice conditions are associated with differences in abundances or species composition of microzooplankton through an examination of tintinnids and radiolarians. From 18 stations in 2011, and 19 stations in 2012, organisms were enumerated in plankton net tow material, and chlorophyll determinations made (total and ≤ 20 μm) from discrete depth samples. We found that the low sea ice conditions of 2012 were associated with higher chlorophyll concentrations (both total and the ≤ 20 μm size fraction), compared to 2011. However, tintinnid ciliates and radiolarians were much lower in concentration, by about an order of magnitude, compared to 2011. In both years the radiolarian assemblage was dominated by Amphiselma setosa. The species composition of the tintinnid ciliates was similar in the two years, but there were distinct differences in the relative abundances of certain species. The 2012, low sea ice assemblage, was dominated by small forms in contrast to 2011, when large species were the most abundant. We present these findings in detail and discuss possible explanations for the apparent differences in the microzooplankton communities associated with distinct sea ice conditions in the Chukchi Sea.
Źródło:
Acta Protozoologica; 2014, 53, 1
1689-0027
Pojawia się w:
Acta Protozoologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Manufacture of MoO3 Coating Layer Using Thermal Spray Process and Analysis of Microstructure and Properties
Autorzy:
Hwang, Yu-Jin
Kim, Kyu-Sik
Park, Jae-Sung
Lee, Kee-Ahn
Powiązania:
https://bibliotekanauki.pl/articles/2174568.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
MoO3
thermal spray
atmospheric plasma spray
microstructure
properties
Opis:
MoO3 thick film was manufactured by using a thermal spray process (Atmospheric Plasma Spray, or APS) and its micro-structure, phase composition and properties of the coating layer were investigated. Initial powder feedstock was composed of an orthorhombic α-MoO3 phase, and the average powder particle size was 6.7 μm. As a result of the APS coating process, a MoO3 coating layer with a thickness of about 90 μm was obtained. Phase transformation occurred during the process, and the coating layer consisted of not only α-MoO3 but also β-MoO3, MoO2. Phase transformation could be due to the rapid cooling that occurred during the process. The properties of the coating layer were evaluated using a nano indentation test. Hardness and reduced modulus were obtained as 0.47 GPa and 1.4 GPa, respectively. Based on the above results, the possibility of manufacturing a MoO3 thick coating layer using thermal spray is presented.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 4; 1535--1538
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Education and Research on Polish Studies in Korea
Autorzy:
Cheong, Kwon Byung
Kim, Jong Suck
Choi, Sung Eun (Estera Czoj)
Kim, Yong Deog
Kim, Ji Young
Lee, Ok Jin
Lee, Ji Wone
Koh, Seung Hui
Powiązania:
https://bibliotekanauki.pl/articles/26414309.pdf
Data publikacji:
2013-06-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Polish studies
Korea
Department of Polish Studies
HUFS
Opis:
Polish education and research in Korea has become systematic since the establishment of the Department of Polish Studies at Hankuk University of Foreign Studies (HUFS). The Department of Polish Studies at HUFS is the only academic department in Korea which teaches and studies the politics, economy, history, and culture of Poland, as well as the Polish language and literature. Since its establishment in 1987, the department has produced more than 800 graduates. The Department of Polish Studies forms and maintains a close relationship with universities in Poland. It also makes continuous effort for more students to study the Polish language at universities in Poland.
Źródło:
The New Educational Review; 2013, 32; 19-34
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of Weldability of Hot-Dip Galvanized Steel by Anti-Galvanizing Coating with Si-Fe-Al Oxide-Based Micropowder
Autorzy:
So, Seong-Min
Kim, Ki-Yeon
Park, Il-Song
Lee, Seok-Jae
Yoo, Dong-Jin
Kim, Yeon-Won
Oh, Min-Suk
Powiązania:
https://bibliotekanauki.pl/articles/2203718.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hot-dip galvanizing
anti-galvanizing
oxide micropowder
weldability
Opis:
A Si-Fe-Al ternary oxide-based micropowder coating was used to prevent the formation of a Zn coating on steel during the hot-dip Zn galvanizing process to reduce the welding fume and defects generated during the welding of Zn-galvanized steel. The composition ratio of the oxide powder was optimized and its microstructure and weldability were evaluated. The optimized oxide coating was stable in the hot-dip galvanizing bath at 470°C and effectively inhibited the formation of Zn coating. The Zn residue could be easily removed with simple mechanical impact. The proposed coating reduced Zn fume and prevented the residual Zn from melting in the weld bead during high-temperature welding, thus reducing the number of welding defects. The results indicated that this pretreatment can simplify the manufacturing process and shorten the process time cost-effectively.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 155--159
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on Magnetic Properties of the U-Type Ferrite According to Substituted Elements
Autorzy:
Jeong, Kwang-Pil
Kim, Jeong-Gon
Yang, Su-Won
Yun, Jae-Ho
Choi, Jin-Hyuk
Powiązania:
https://bibliotekanauki.pl/articles/354006.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
U-type ferrite
hexagonal ferrite
sol-gel process
Opis:
The magnetic properties of the U-type ferrite synthesized by a sol-gel process had studied by substituting cobalt with manganese or zinc in cobalt-based U-type ferrite. The substituted U-type ferrite showed a dominant crystal structure at a different substitution ratio of manganese and zinc. The change of the starting temperature of U-type ferrite formation according to substitutional elements was confirmed by TG-DTA analysis. In the case of manganese substitution, the starting temperature of U-type ferrite formation lowered, and on the contrary, when zinc was substituted, it became higher. The magnetic properties of the U-type ferrite substituted with manganese showed a tendency that the saturation magnetization was decreased and the coercivity was increased as the manganese ratio increased. The highest saturation magnetization was 57.9 emu/g in the specific composition (Ba4Co0.5Zn1.5Fe36O60) substituted with zinc.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 501-505
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of Microwave Absorption Characteristics by Coating Layer in Substituted U-Type Ferrites
Autorzy:
Jeong, Kwang-Pil
Kim, Jeong-Gon
Yang, Su-Won
Choi, Jin-Hyuk
Park, Seung-Young
Powiązania:
https://bibliotekanauki.pl/articles/353196.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hexagonal ferrite
U-type ferrite
silicon oxide layer
microwave absorption
Opis:
The U-type ferrite is a kind of hexagonal ferrite, and it is known as a microwave absorber in the X-band. The magnetic and dielectric loss of the U-type ferrite change to the composition and coating layer, etc. In this study, the silicon oxide layer was coated on the substituted U-type ferrites to improve microwave absorption characteristics. The complex permittivity and complex permeability were measured using toroidal specimens that were press-molded and the measured frequency range was set from 2-18 GHz. The improvement of the microwave absorption rate was different according to the type of the substituted U-type ferrites. Only in the substituted U-type ferrites with nickel and zinc, an improvement in the microwave absorption rate due to enhancement of magnetic loss was confirmed. The highest microwave absorption was 99.9% at 9.6 GHz, which was S_Z0.5 U.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1287-1291
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and performance of dual-band MWIR/LWIR focal plane arrays based on a type-II superlattice nBn structure
Autorzy:
Lee, Hyun-Jin
Eom, Jun Ho
Jung, Hyun Chul
Kang, Ko-Ku
Ryu, Seong Min
Jang, Ahreum
Kim, Jong Gi
Kim, Young Ho
Jung, Han
Kim, Sun Ho
Choi, Jong Hwa
Powiązania:
https://bibliotekanauki.pl/articles/2204217.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
InAs/GaSb type-II superlattice
dualband detector
dark current
spectral quantum efficiency
noise equivalent temperature difference
Opis:
Dual-band infrared detector, which acquires more image information than single-band detectors, has excellent detection, recognition, and identification capabilities. The dual-band detector can have two bumps to connect with each absorber layer, but it is difficult to implement small pitch focal plane arrays and its fabrication process is complicated. Therefore, the most effective way for a dual-band detector is to acquire each band by biasselectable with one bump. To aim this, a dual-band MWIR/LWIR detector based on an InAs/GaSb type-II superlattice nBn structure was designed and its performance was evaluated in this work. Since two absorber layers were separated by the barrier layer, each band can be detected by bias-selectable with one bump. The fabricated dual-band device exhibited the dark current and spectral response characteristics of MWIR and LWIR bands under negative and positive bias, respectively. Spectral crosstalk that is a major issue in dualband detectors was also improved. Finally, a 20 µm pitch 640 x 512 dual-band detector was fabricated, and both MWIR and LWIR images exhibited an average noise equivalent temperature difference of 30 mK or less at 80 K.
Źródło:
Opto-Electronics Review; 2023, 31, Special Issue; art. no. e144560
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Efficiency Cooling System Using Additive Manufacturing
Autorzy:
Woo, Yeong-Jin
Nam, Dong-Ho
Lee, Seok-Rok
Kim, Eun-Ah
Lee, Woo-Jin
Yang, Dong-Yeol
Yu, Ji-Hun
Park, Yong-Ho
Lee, Hak-Sung
Powiązania:
https://bibliotekanauki.pl/articles/2049198.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
additive manufacturing
DfAM
Design for Additive Manufacturing
cooling system
lattice structure
simulation
Opis:
In this study, we propose a cooling structure manufactured using a specialized three-dimensional (3D) printing design method. A cooling performance test system with complex geometry that used a thermoelectric module was manufactured using metal 3D printing. A test model was constructed by applying additive manufacturing simulation and computational fluid analysis techniques, and the correlation between each element and cooling efficiency was examined. in this study, the evaluation was conducted using a thermoelectric module base cooling efficiency measurement system. The contents were compared and analyzed by predicting the manufacturing possibility and cooling efficiency, through additive manufacturing simulation and computational fluid analysis techniques, respectively.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 3; 689-693
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mismatch in working hours and workaholism in permanent waged workers
Autorzy:
Park, Shin-Goo
Kim, Hyung-Doo
Min, Jin-Young
Min, Kyoug-Bok
Hwang, Sang-Hee
Jang, Eun-Chul
Powiązania:
https://bibliotekanauki.pl/articles/2116653.pdf
Data publikacji:
2020-03-13
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
workaholism
working hours mismatch
waged worker
workaholic
mismatched
weekly working hours
Opis:
ObjectivesA cross-sectional study was conducted to investigate whether working hours mismatch is associated with workaholism.Material and MethodsThis study used the data from the 17th wave (2014) of the nationwide Korean Labor and Income Panel Study. Workaholism was evaluated using the Workaholism Analysis Questionnaire. The final study involved 3157 subjects who answered questions regarding both workaholism and working hours mismatch. To identify the association between working hours mismatch and workaholism according to weekly working hours, a stratification analysis was conducted by dividing the number of working hours/week into 3 groups (≤40 h, 41–59 h, and ≥60 h). The odds ratios were calculated using a multiple logistic regression model, which was adjusted for potential confounders.ResultsThe workers working more hours than desired showed the greatest frequency of workaholism. As regards workaholism, in all weekly working hours groups, the odds ratios of the group working more hours than desired were 4.28, 95% CI: 2.29–7.99 (≥40 h), 2.14, 95% CI: 1.34–3.43 (41–59 h), 3.40, 95% CI: 1.60–7.21 (≤60 h), which were statistically significant compared to the reference (matched) group. There was no statistically significant relationship between working hours and workaholism when stratified according to the mismatch in working hours.ConclusionsThe workers’ working hours mismatch can be significantly related to workaholism.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2020, 33, 2; 187-194
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of Metal Gas Filter by Material Extrusion Additive Manufacturing Process
Autorzy:
Yi, Yu-Jeong
Lee, Min-Jeong
Yun, Su-Jin
Park, Manho
Kim, Ju-Yong
Lee, Jungwoo
Yun, Jung-Yeul
Powiązania:
https://bibliotekanauki.pl/articles/2174560.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gas filter
additive manufacturing
stainless steel
porosity
powder size
Opis:
Recently, 3D printing processes have been used to manufacture metal powder filters with manufacturing complex-shape. In this study, metal powder filters of various shapes were manufactured using the metal extrusion additive manufacturing (MEAM) process, which is used to manufacture three-dimensional structures by extruding a filament consisting of a metal powder and a binder. Firstly, filaments were prepared by appropriately mixing SUS316 powder with sizes ranging from 7.5 µm to 50 µm and a binder. These filaments were extruded at temperatures of 100℃ to 160℃ depending on the type of filament being manufactured, to form three types of cylindrical filter. Specimens were sintered in a high vacuum atmosphere furnace at 850℃ to 1050℃ for 1 hour after debinding. The specimens were analyzed for permeability using a capillary flow porometer, porosity was determined by applying Archimedes’ law and microstructure was observed using SEM.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 4; 1517--1520
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of 4N5 Grade Tantalum Wire from Tantalum Scrap by EBM and Drawing
Autorzy:
Yu, Ji-Won
Choi, Sang-Hoon
Sim, Jae-Jin
Lim, Jae-Hong
Seo, Kyoung-Deok
Hyun, Soong-Keon
Kim, Tae-Youb
Gu, Bon-Woo
Park, Kyoung-Tae
Powiązania:
https://bibliotekanauki.pl/articles/353005.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electron beam melting
drawing
tantalum scrap
recycling
high purity
Opis:
Electron beam melting(EBM) is a useful technique to obtain high-purity metal ingots. It is also used for melting refractory metals such as tantalum, which require melting techniques employing a high-energy heat source. Drawing is a method which is used to convert the ingot into a wire shape. The required thickness of the wire is achieved by drawing the ingot from a drawing die with a hole of similar size. This process is used to achieve high purity tantalum springs, which are an essential component of lithography lamp in semiconductor manufacturing process. Moreover, high-purity tantalum is used in other applications such as sputtering targets for semiconductors. Studies related to recycling of tantalum from these components have not been carried outuntil now. The recycling of tantalum is vital for environmental and economic reasons. In order to obtain high-purity tantalum ingot, in this study impurities contained in the scrap were removed by electron beam melting after pre-treatment using aqua regia. The purity of the ingot was then analyzed to be more than 4N5 (99.995%). Subsequently, drawing was performed using the rod melted by electron beam melting. Owing to continuous drawing, the diameter of the tantalum wire decreased to 0.5 mm from 9 mm. The hardness and oxygen concentration of the tantalum ingot were 149 Hv and less than 300 ppm, respectively, whereas the hardness of the tantalum wire was 232.12 Hv. In conclusion, 4N5 grade tantalum wire was successfully fabricated from tantalum scrap by EBM and drawing techniques. Furthermore, procedure to successfully recycle Tantalum from scraps was established.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 935-941
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production of High-Purity Tantalum Metal Powder for Capacitors Using Self-Propagating High-Temperature Synthesis
Autorzy:
Lee, Yong-Kwan
Sim, Jae-Jin
Byeon, Jong-Soo
Lee, Yong-Tak
Cho, Yeong-Woo
Kim, Hyun-Chul
Heo, Sung-Gue
Lee, Kee-Ahn
Seo, Seok-Jun
Park, Kyoung-Tae
Powiązania:
https://bibliotekanauki.pl/articles/2049150.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tantalum
self-propagating high-temperature synthesis
tantalum oxide
magnesium
capacitor
Opis:
In this study, high-purity tantalum metal powder was manufactured via self-propagating high-temperature synthesis. During the process, Ta2O5 and Mg were used as the raw material powder and the reducing agent, respectively, and given that combustion rate and reaction temperature are important factors that influence the success of this process, these factors were controlled by adding an excessive mass of the reducing agent (Mg) i.e., above the chemical equivalent, rather than by using a separate diluent. It was confirmed that Ta metal powder manufactured after the process was ultimately manufactured 99.98% high purity Ta metal powder with 0.5 μm particle size. Thus, it was observed that adding the reducing reagent in excess favored the manufacture of high-purity Ta powder that can be applied in capacitors.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 4; 935-939
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of ZrO2 and Al2O3 Addition on the Physical Properties of Cu-Mo-Cr Alloy by Liquid Phase Sintering
Autorzy:
Cho, Yeong-Woo
Sim, Jae-Jin
Heo, Sung-Gue
Kim, Hyun-Chul
Lee, Yong-Kwan
Byeon, Jong-Soo
Lee, Yong-Tak
Lee, Kee-Ahn
Seo, Seok-Jun
Park, Kyoung-Tae
Powiązania:
https://bibliotekanauki.pl/articles/2049193.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al2O3
ZrO2
Cu-Mo-Cr
sintering
powder metallurgy
Opis:
In this study, the effect of the addition of ZrO2 and Al2O3 ceramic powders to Cu-Mo-Cr alloy was studied by examining the physical properties of the composite material. The ceramic additives were selected based on the thermodynamic stability calculation of the Cu-Mo-Cr alloys. Elemental powders, in the ratio Cu:Mo:Cr = 60:30:10 (wt.%), and approximately 0-1.2 wt.% of ZrO2 and Al2O3 were mixed, and a green compact was formed by pressing the mixture under 186 MPa pressure and sintering at 1250°C for 5 h. The raw powders were evenly dispersed in the mixed powder, as observed by scanning electron microscopy. After sintering, the microstructures, densities, electrical conductivities, and hardness of the composites were evaluated. We found that the addition of ZrO2 and Al2O3 increased the hardness and decreased the electrical conductivity and density of the composites.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 3; 683-687
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
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