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Wyświetlanie 1-25 z 25
Tytuł:
Measurement of surface subsidence and ground collapse caused by underground mining in the Boleo Copper District, Mexico
Autorzy:
Kim, Jong-Gwan
Powiązania:
https://bibliotekanauki.pl/articles/1839040.pdf
Data publikacji:
2020
Wydawca:
Główny Instytut Górnictwa
Tematy:
subsidence
vertical movements
copper mine
surface crack
longwall
underground mine
osiadanie
ruchy pionowe
kopalnia miedzi
pęknięcie powierzchniowe
ściana eksploatacyjna
kopalnia podziemna
Opis:
Subsidence and vertical movements in mines are a challenge in mining operations. To qualify as a controlled mine site, ground movements must be measured regularly during mining operations. Boleo Copper District mine was monitored and the movement during mining operations was measured from Oct. 31, 2018 to March 15, 2019. The evaluation of vertical and horizontal movement was determined in four locations in the mine areas M303, M303S, M303 C, and M305. The exploitation area, which measured approximately 80 £ 90 m2 with a height of 2.4 m, impacted the surface in the form of cracks. These cracks were observed on the topographic surveys and varied during the mining operations from the beginning to the end. The final results indicated that the points with the greatest displacement were those in the central zone of the mine excavation (points #3, 5, and 6) and the displacement trend of the ground was toward this zone. In theory, the subsidence is typically lesser than the thickness of the extracted ore. In this case, the maximum subsidence was 1.15 m and the ore seam thickness was 2.4 m. The maximum possible subsidence is typically 55-65% of the extracted seam thickness; however, because chain pillars are generally left in place, and provide some support, this maximum possible subsidence is rarely reached. In this case, the maximum subsidence was 52% of the seam thickness.
Źródło:
Journal of Sustainable Mining; 2020, 19, 2; 126-134
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selection mining methods via multiple criteria decision analysis using TOPSIS and modification of the UBC method
Autorzy:
Ali, Mahrous A.M.
Kim, Jong-Gwan
Powiązania:
https://bibliotekanauki.pl/articles/1839056.pdf
Data publikacji:
2021
Wydawca:
Główny Instytut Górnictwa
Tematy:
TOPSIS
UBC method
mining method selection
multiple criteria decision making
metoda UBC
wybór metod wydobycia
wielokryterialne podejmowanie decyzji
Opis:
Mine designers often face difficulties in selecting an appropriate mining method; however, such a method should be selected based on ore and rock characteristics. The selection of mining methods can be considered a type of multi-criteria decision making, and this depends on many factors used in the selection process. The general method used in this field is the University of British Columbia (UBC) method, which determines the criteria of the properties that are compared to determine the best and worst of several mining methods. In this paper we used as new technique which defines as Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The criteria considered in the UBC method include general shape, ore thickness, ore plunge, and grade distribution, beside the rock quality designation (RQD), and the rock substance strength (RSS). This paper presents an improved TOPSIS method based on experimental design. Additionally, this paper will introduce a modified version of the UBC method that can be employed based on Excel sheet. The best mining methods is cut and fill stoping and top slicing with the same rank equal 0.72, and the second-best mining method is square set stoping with rank equal 0.65.
Źródło:
Journal of Sustainable Mining; 2021, 20, 2; 49-55
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of and Prospects for Students’ Academic Performance in Polish History Education
Autorzy:
Kim, Yong-Deog
Lee, Jong-Oh
Kim, Jong-Suck
Powiązania:
https://bibliotekanauki.pl/articles/48527145.pdf
Data publikacji:
2012-06-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Polska
Korea
Polish history
Korean students
Department of Polish
Opis:
For this study, an evaluation tool focusing on the Polish history was developed to measure the academic performance of college students who major in the Polish language in Korea. The purpose of this study was to investigate the effects of the tool on students’ academic performance after applying it in a classroom setting. The tool consisted of three types of questions, which were administered before and after the application of the tool to 108 students taking a Polish history course. The results of the study serve as a foundation for revitalizing research on Poland and Polish language education, as well as for improving students’ academic performance.
Źródło:
The New Educational Review; 2012, 28; 61-72
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:
Effect of an eccentric decoupled charge on rock mass blasting
Autorzy:
Kim, Jung-Gyu
Ali, Mahrous A.M.
Kim, Jong-Gwan
Powiązania:
https://bibliotekanauki.pl/articles/1839045.pdf
Data publikacji:
2020
Wydawca:
Główny Instytut Górnictwa
Tematy:
eccentric decoupled charge
fracture pattern
PFC
AUTODYN
decoupling index
wzór pęknięcia
wskaźnik odsprzęgania
Opis:
Experimental and numerical analyses were conducted to investigate the effect of an eccentric loaded contour hole on a rock mass. In the concrete blocks used for the analyses, detonating cords were placed at the centre of the blast hole and eccentrically against the wall of the blast hole. PFC2D and AUTODYN were used for the numerical analyses, and the results of these software showed that an eccentric decoupled charge can result in the directional development of fractures, thereby enabling the control of cracks in the opposite direction. Even though both types of blasting have identical decoupling indexes, the crack and fracture patterns were affected by the location of the explosive, tamping, and other conditions. The results showed that an eccentric charge holder can be applicable to control the fracture direction and the damaged zone. For an eccentric charge, the initial crack was generated at 0.01 ms and expanded in the intended direction. For the eccentric charge, the maximum pressure at the area in contact with the blast hole wall exceeded that for the central decoupled charge by a factor of 5.5. Furthermore, the pressure in the intended direction was twice of that in the opposite direction.
Źródło:
Journal of Sustainable Mining; 2020, 19, 1; 1-10
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of T6 Heat Treatment on the Scratch Wear Behavior of Extruded Al-12wt.%Si Alloy
Autorzy:
Kang, Yeon-Ji
Kim, Jong-Ho
Hwang, Jong-Il
Lee, Kee-Ahn
Powiązania:
https://bibliotekanauki.pl/articles/356776.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-12wt.%Si alloy
scratch test
wear-resistance
T6 heat treatment
Opis:
This study investigated the effect of T6 heat treatment on the microstructure and scratch wear behavior of hypoeutectic Al-12wt.%Si alloy manufactured by extrusion. Microstructural observation identified spherical eutectic Si phases before and after the heat treatment of alloys (F, T6). Phase analysis confirmed Al matrix and Si phase as well as Al2Cu and Al3Ni, Mg2Si in both alloys. In particular, Al2Cu was finer and more evenly distributed in T6 alloy. This resulted in Vickers hardness of T6 alloy that was 2.3 times greater compared to F alloy. The scratch wear test was conducted using constant load scratch test (CLST) mode and multi-pass scratch test (MPST) mode. The scratch coefficient and worn out volume obtained by such were used to evaluate wear properties before and after heat treatment. In the case of T6 alloy, its scratch coefficient was lower than F alloy in all load ranges. After 15 repeated tests to measure worn out volume, F alloy and T6 alloy measured 1.2×10-1 mm3 and 7.8×10-2 mm3, respectively. In other words, the wear resistance of T6 alloy were confirmed to be better than those of F alloy. In addition, this study attempted to identify the microstructural factors that contribute to the better scratch wear resistance of T6 alloy and wear mechanism from surface and cross-section observations after the wear tests.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 617-622
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:
High-performance high-speed WIM for sustainable road load monitoring using GIS technology
Autorzy:
Kim, Jong Woo
Jung, Young Woo
Utebayeva, Ainura
Kamaliyeva, Zhuldyz
Collins, Neil
Sarbassov, Dastan
Sagin, Janay
Amanzhlova, Raushan
Powiązania:
https://bibliotekanauki.pl/articles/2098176.pdf
Data publikacji:
2021
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
WIM
weight-in-motion
silk road
one belt
KAIA
ważenie pojazdów w ruchu
jedwabny szlak
jeden pas
Opis:
The increasing importance of better transport connectivity has indicated the need to develop high-speed road load monitoring technologies. The Belt and Road Initiative (BRI), Silk Road transportation programs considerable have developed the roads and highways networks in Kazakhstan and other Central Asian (CA) countries. Transportation services require proper maintenance and prompt track load monitoring. There is no holistic freight traffic management system that controls and monitors traffic flow in CA. A Weigh in Motion (WIM) technology can be used as an effective traffic management control system in the CA region. The WIM technology is designed to control axle and gross vehicle weight in motion. It has a wide range of applications, including pavement and bridge weight control, traffic legislation and state regulations. The WIM technology has advantages over conventional static weighing as it does not interrupt traffic flow by creating queues at monitoring stations. The WIM technology can be used not only as a weight control tool but also performs a comprehensive analysis of other traffic flow parameters. In cooperation with Korean UDNS experts with suport from KAIA, we test the application of WIM in Nur-Sultan city, North of Kazakhstan, with Siberian-type cold weather. These works create much challenges and innovative approach to test sensors in the harsh environment, from the extreme cold to hot temperatures, with intensive dust distortions. Our Talapker WIM pilot test site was installed in September 2020, and it performs Gross Vehicle Weight (GVW) and Axle of Weight (AOW) analyses. The Talapker WIM High Speed (HS) sensors are capable of detecting different driving patterns, including everyday driving, acceleration or deceleration more than 10km/h/s and eccentric driving (partial contact with the platform to avoid excessive weighting). The pilot Talapker HS WIM site has demonstrated a positive effect on implementing WIM technology in Kazakhstan. Every 10th car passing through the WIM site registered as an overloaded vehicle by gross weighting, and every 5th car is considered overloaded by axle weighting. GIS-based location allocation analysis (LAA) performed in the given study provided an understanding of a practical implementation of WIM sensors. Taking into consideration different geographical data, the WIM site map was developed to reveal 43 suitable locations. Further improvements for the CA road network and their WIM demand points will be the focus of future research investigations.
Źródło:
Transport Problems; 2021, 16, 4; 149--162
1896-0596
2300-861X
Pojawia się w:
Transport Problems
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:
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:
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:
Social science education offered by Chinese Departments in Korean universities
Autorzy:
Nam, Jong-ho
Kim, Insik
Kim, Yongdeog
Powiązania:
https://bibliotekanauki.pl/articles/2004959.pdf
Data publikacji:
2016-06-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
Chinese studies in Korea
Chinese social sciences
Chinese language and literature
two-track curricula
Opis:
The current curricula of the departments of Chinese in Korea emphasize language and literature, although most students in these departments would prefer an emphasis on curricula in the Chinese social sciences, with less emphasis on language and literature. The research reported here include surveys that identified needs as perceived by students, and contrasted these with studies of existing Korean departments of Chinese. This research indicates that Korean universities currently lack the ability to meet students’ needs. For more effective education, Chinese departments should offer two-track curricula, consisting of a language track and a social science track.
Źródło:
The New Educational Review; 2016, 44; 17-29
1732-6729
Pojawia się w:
The New Educational Review
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:
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:
Effect of Aspect Ratio on Iron-Ore Briquettes During Twin-Roll Briquetting
Autorzy:
Kim, Kang-Min
Bae, Jong-Ho
Han, Jeong-Whan
Powiązania:
https://bibliotekanauki.pl/articles/355616.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical analysis
discrete element method
roll briquetting
Opis:
In the ironmaking, sizes of raw materials such as iron ores and coke must be adjusted for subsequent process in the blast furnace. The depletion of high grade iron ore in recent years necessitates a technology that can utilize low-grade fine iron ores. Thus, steelmakers have been studying the sinter-briquette complex firing process that employs a method of charging the sinter feed together with briquettes made of fine iron ore. In this process, larger briquettes increase the briquette productivity per unit time but decrease the green strength of briquettes and they can break during transportation and charging. Thus, the briquette shape is very important. Therefore, in this study, we simulate a twin roll briquetting process using the DEM analysis and compared the compressive force distributions in the briquette for different aspect ratios. This study is a new attempt, because research cases by numerical methods on the same or similar systems are very rare. Consequently, the optimal aspect ratio is 0.5 at briquette height 20 mm, 2.0 at 30 mm, and 1.5 at 40 mm. Also, the average compressive force increased in proportion with the pocket height at the sameaspect ratio. Therefore, to increase the pocket depth for high productivity, the pocket height must also be increased for obtaining high strength briquettes.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1335-1339
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Substrate Temperature on Magnetic and Structural Properties of RF Magnetron Sputtered Co-Cr Thin Films
Autorzy:
Baek, Jong-Sung
Kim, Yark-Yeon
Lim, Woo-Young
Kim, Yurng-Dae
Yu, Seong-Cho
Powiązania:
https://bibliotekanauki.pl/articles/1955470.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ss
Opis:
The present paper describes the substrate temperature T$\text{}_{s}$ dependence on magnetic and structural properties of Co-21 at.% Cr thin films deposited on the Corning glass substrate by RF magnetron sputtering. The properties of the samples, such as saturation magnetization M$\text{}_{s}$, in-plane squareness ratio S$\text{}_{∥}$, effective magnetic anisotropy field H'$\text{}_{k}$, spectroscopic splitting factor g, and hcp (002) peak intensity I$\text{}_{002}$, were examined by vibrating sample magnetometer, Q-band (≈ 33.9 GHz) ferromagnetic resonance measurements and X-ray diffractometry. Specially, the presence of the various ferromagnetic constituents in Co-Cr thin films are examined by the ferromagnetic resonance studies. With increasing T$\text{}_{s}$ from room temperature to 200°C, S$\text{}_{∥}$ increases from 0.08 to 0.56 but H'$\text{}_{k}$ decreases from 2530 Oe to -3900 Oe. Also I$\text{}_{002}$ decreases with increasing T$\text{}_{s}$. It is summarized that the perpendicular magnetic anisotropy and c-axis orientation of Co-Cr films are improved at lower substrate temperature.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 307-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics of a new respiratory syndrome associated with the use of a humidifier disinfectant: humidifier disinfectant-related respiratory syndrome (HDRS)
Autorzy:
Leem, Jong Han
Joh, Joon-Sung
Hong, Young-Seoub
Kim, Jungwon
Park, Soyoung
Lim, Soyeoun
Kim, Yangho
Powiązania:
https://bibliotekanauki.pl/articles/2116504.pdf
Data publikacji:
2020-10-20
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
pneumonitis
respiratory
lung
disinfection
injuries
humidifier
Opis:
ObjectivesThe purpose of this study was to characterize a new respiratory syndrome associated with exposure to a humidifier disinfectant (HD) in South Korea that is distinct from the well-known HD-related lung injury (HDLI). The authors identified this condition in 24 study subjects who were family members of patients with definite or probable HDLI (referred to as index cases), and were exposed to HD in the same room as the index cases.Material and MethodsThe authors reviewed medical records of 236 family members in 110 families who were exposed to HD in the same rooms and residences as the index cases.ResultsThey identified 24 family members who were exposed to HD in the same rooms and residences as the index cases, and who developed respiratory disorders that were distinct from HDLI. The clinical signs and symptoms of these individuals were in the upper respiratory tract, such as allergic rhinitis and croup, or in the lower respiratory tract, such as bronchitis and pneumonia. The diffusing capacity of the lung fordetermicarbon monoxide was reduced in 9 of 12 children (data not available for 1 child), and in 4 of 5 adults (data not available for 6 adults). The percent forced vital capacity and forced expiratory volume in one second/forced vital capacity ratios were within the normal ranges in most patients. The computed tomography findings, which mostly indicated non-specific inflammation, were inconsistent with the radiological diagnostic criteria for HDLI, but were abnormal in 8 of 11 adults, and in 2 of 13 children.ConclusionsThe authors propose a new condition, i.e., HD-related respiratory syndrome (HDRS), which is characterized by mild to moderate or atypical respiratory symptoms and signs, and is related to HD exposure, but is distinct from HDLI. The recognition of HDRS may provide a basis for understanding the natural history of HD-related respiratory problems, and for capturing the whole spectrum of HD-related clinical manifestations in the respiratory tract.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2020, 33, 6; 829-839
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Adding Niobium and Vanadium to Fe-Based Oxide Dispersion Strengthened Alloy
Autorzy:
Park, Chun Woong
Choi, Won June
Byun, Jong Min
Kim, Young Do
Powiązania:
https://bibliotekanauki.pl/articles/353024.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Fe-based ODS
vanadium
niobium
superalloy
hardness
Opis:
In this study, the effects of adding niobium and vanadium to Fe-based oxide dispersion strengthened alloys are confirmed. The composition of alloys are Fe-20Cr-1Al-0.5Ti-0.5Y2 O3 and Fe-20Cr-1Al-0.5Ti-0.3V-0.2Nb-0.5Y2 O3. The alloy powders are manufactured by using a planetary mill, and these powders are molded by using a magnetic pulsed compaction. Thereafter, the powders are sintered in a tube furnace to obtain sintered specimens. The added elements exist in the form of a solid solution in the Fe matrix and suppress the grain growth. These results are confirmed via X-ray diffraction and scanning electron microscopy analyses of the phase and microstructure of alloys. In addition, it was confirmed that the addition of elements, improved the hardness property of Fe-based oxide dispersion strengthened alloys.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1265-1268
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current status of intestinal parasitic infections among inhabitants of the Ghazni and Parwan provinces, Afghanistan
Autorzy:
Korzeniewski, Krzysztof
Chin Chung, Won
Augustynowicz, Alina
Lass, Anna
Jong IK, Kim
Powiązania:
https://bibliotekanauki.pl/articles/553070.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Przyjaciół Medycyny Rodzinnej i Lekarzy Rodzinnych
Tematy:
intestinal parasites
helminths
protozoa
Afghanistan.
Źródło:
Family Medicine & Primary Care Review; 2017, 1; 23-28
1734-3402
Pojawia się w:
Family Medicine & Primary Care Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of Molybdenum Alloy with Distributed High-Entropy Alloy Via Pressureless Sintering
Autorzy:
Choi, Won June
Park, Cheon Woong
Byun, Jong Min
Kim, Young Do
Powiązania:
https://bibliotekanauki.pl/articles/353990.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
molybdenum alloy
high-entropy alloys
core-shell powder
Opis:
In this study, a molybdenum alloy with dispersed high-entropy particles was fabricated using the powder metallurgy method. The high-entropy powder, composed of Nb, Ta, V, W, and Zr elements with a same atomic fraction, was prepared via high-energy ball milling. Using this powder, an ideal core-shell powder, composed of high-entropy powder as core and Mo powder as shell, was synthesized via the milling and reduction processes. These processes enabled the realization of an ideal microstructure with the high-entropy phase uniformly dispersed in the Mo matrix. The sintered body was successfully fabricated via uniaxial compaction followed by pressureless sintering. The sintered body was analyzed by X-ray diffraction and scanning electron microscope, and the high-entropy phase is uniformly dispersed in the Mo matrix.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1269-1272
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dilatometric Analysis of the Sintering Behavior of Bi2Te3 Thermoelectric Powders
Autorzy:
Han, Ju-Yeon
Byun, Jong Min
Lee, Young-In
Choi, Byung Joon
Kim, Hogyoung
Oh, Sung-Tag
Powiązania:
https://bibliotekanauki.pl/articles/354899.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Bi2Te3
dilatometric analysis
sintering behavior
microstructure
Opis:
The sintering behavior of p-type bismuth telluride powder is investigated by means of dilatometric analysis. The alloy powders, prepared by ball milling of melt-spun ribbons, exhibit refined and flake shape. Differential thermal analysis reveals that the endothermic peak at about 280°C corresponds to the melting of bismuth, and peaks existing between 410°C and 510°C are presumably due to the oxidation and crystallization of the powder. The shrinkage behavior of ball-milled powders was strongly dependent of heating rate by the thermal effect exerted on specimens. In the case of 2°C/min, the peak temperature for the densification is measured at 406°C, while the peak temperature at a heating rate of 20°C/min is approximately 443°C. The relative density of specimen pressureless-sintered at 500°C exhibited relatively low value, and thus further study is required in order to increase the density of sintered body.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 3; 1117-1120
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiple assessment methods of prenatal exposure to radio frequency radiation from telecommunication in the Mothers and Children’s Environmental Health (MOCEH) study
Autorzy:
Choi, Kyung-Hwa
Ha, Mina
Burm, Eunae
Ha, Eun-Hee
Park, Hyesook
Kim, Yangho
Lee, Ae-Kyoung
Kwon, Jong Hwa
Choi, Hyung-Do
Kim, Nam
Powiązania:
https://bibliotekanauki.pl/articles/2168386.pdf
Data publikacji:
2016-11-18
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
prenatal exposure
validation
mobile phone
radio frequency radiation
MOCEH
personal exposure meter
Opis:
Objectives To evaluate prenatal exposure to radiofrequency radiation (RFR) from telecommunication using a mobile phone questionnaire, operator data logs of mobile phone use and a personal exposure meter (PEM). Material and Methods The study included 1228 mother–infants pairs from the Mothers and Children’s Environmental Health (MOCEH) study – a multicenter prospective cohort study ongoing since 2006, in which participants were enrolled at ≤ 20 weeks of pregnancy, with a follow-up of a child birth and growth to assess the association between prenatal environmental exposure and children’s health. The questionnaire included the average calling frequency per day and the average calling time per day. An EME Spy 100 PEM was used to measure RFR among 269 pregnant women from November 2007 to August 2010. The operators’ log data were obtained from 21 participants. The Spearman’s correlation test was performed to evaluate correlation coefficient and 95% confidence intervals between the mobile phone use information from the questionnaire, operators’ log data, and data recorded by the PEM. Results The operators’ log data and information from the self-reported questionnaire showed significantly high correlations in the average calling frequency per day (ρ = 0.6, p = 0.004) and average calling time per day (ρ = 0.5, p = 0.02). The correlation between information on the mobile phone use in the self-reported questionnaire and exposure index recorded by the PEM was poor. But correlation between the information of the operators’ log data and exposure index for transmission of mobile communication was significantly high: correlation coefficient (p-value) was 0.44 (0.07) for calling frequency per day, and it was 0.49 (0.04) for calling time per day. Conclusions The questionnaire information on the mobile phone use showed moderate to high quality. Using multiple methods for exposure assessment might be better than using only one method. Int J Occup Med Environ Health 2016;29(6):959–972
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2016, 29, 6; 959-972
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
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
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
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