Autor: Choi, J. H. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Compositional Dependence of Hardness of Ge-Sb-Se Glass for Molded Lens Applications
Zależność stężeniowa twardości szkła Ge-Sb-Se do zastosowań na formowane soczewki
Autorzy:: Park, J. K.
Lee, J. H.
Shin, S. Y.
Yi, J. H.
Lee, W. H.
Park, B. J.
Choi, J. H.
Kim, N. Y.
Choi, Y. G.
Powiązania:: https://bibliotekanauki.pl/articles/352228.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: chalcogenide glasses
Ge-Sb-Se glass
infrared lens
molded lens
infrared camera
szkło
Ge-Sb-Se
soczewki formowane
twardość szkła
kamera termowizyjna
Opis:: Chalcogenide glass in the ternary Ge-Sb-Se system is inherently moldable, thus being considered as a strong candidate material for use in infrared-transmitting lens applications from the viewpoint of thermal and mechanical stability. In an effort to experimentally determine compositional region suitable for the molded lens applications, we evaluate its compositional dependence of hardness. Among the constituent atoms, Ge content turns out to exert a most conspicuous correlation with hardness. This phenomenological behavior is then explained in connection with the structural evolution that Ge brings about.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1205-1208
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Development of Carbon Nanotube Based Reflection Type X-ray Source
Autorzy:: Choi, H.
Kim, J.
Lee, C.
Powiązania:: https://bibliotekanauki.pl/articles/1807922.pdf
Data publikacji:: 2009-06
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 75.47.Lx
75.47.Gk
73.50.Fq
Opis:: X-ray imaging technology is a useful and leading medical diagnostic tool for health care professionals to diagnose disease in human body. Carbon nanotube based X-ray source, which we have developed in this study, could be also useful and supply integrated diagnostic X-ray imaging tool in diagnosis. Conventionally, thermionic type of tungsten filament X-ray tube is widely employed in the field of biomedical and industrial application fields. However, intrinsic problems, such as poor emission efficiency, low imaging resolution, and high electrical energy consumption etc., may cause the limitation of using the X-ray tube. To fulfill the current market requirement, specifically for medical diagnostic field, we have developed rather a portable and compact carbon nanotube based X-ray device in which microfocus high imaging resolution can be feasible.
Źródło:: Acta Physica Polonica A; 2009, 115, 6; 1078-1080
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Preparation of Submicroscale Ag-Coated Cu Particles by Multi-Step Addition of Ag Plating Solution and Antioxidation Properties for Different Ag Shell Thicknesses
Autorzy:: Choi, E. B.
Lee, J.-H.
Powiązania:: https://bibliotekanauki.pl/articles/351202.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: Ag-coated Cu particle
submicrometer
Glycol-based Ag plating solution
mult-step addition
antioxidation
Opis:: For application as a low-cost conductive filler material, submicroscale Cu@Ag particles were fabricated at room temperature without any reductants by a multi-step addition method using an ethylene glycol-based Ag plating solution. Scanning electron microscopy images of the Ag-coated Cu particles demonstrated the formation of discrete Ag particles less than 100 nm in size as well as a thin Ag coating on Cu particles, during the early addition steps. However, as the thickness of the Ag coating increased, the small Ag particles agglomerated into Ag coatings with an increase in the number of Ag plating steps. Owing to the absence of additives such as surfactants, a comparison between the microstructural images and calculations indicated increased agglomeration between fabricated Ag-coated Cu particles with an increase in the number of Ag plating steps. However, thermogravimetric-differential scanning calorimetry of the agglomerated Ag-coated Cu particles after the fifth addition of the Ag plating solution demonstrated their antioxidation behavior even after 70 min in air at 150°C.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 2B; 1137-1142
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Iterative methods for efficient sampling-based optimal motion planning of nonlinear systems
Autorzy:: Ha, J. S.
Choi, H. L.
Jeon, J. H.
Powiązania:: https://bibliotekanauki.pl/articles/330028.pdf
Data publikacji:: 2018
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:: optimal motion planning
sampling based algorithm
nonlinear dynamics
planowanie ruchu
algorytm próbkowania
dynamika nieliniowa
Opis:: This paper extends the RRT* algorithm, a recently developed but widely used sampling based optimal motion planner, in order to effectively handle nonlinear kinodynamic constraints. Nonlinearity in kinodynamic differential constraints often leads to difficulties in choosing an appropriate distance metric and in computing optimized trajectory segments in tree construction. To tackle these two difficulties, this work adopts the affine quadratic regulator-based pseudo-metric as the distance measure and utilizes iterative two-point boundary value problem solvers to compute the optimized segments. The proposed extension then preserves the inherent asymptotic optimality of the RRT* framework, while efficiently handling a variety of kinodynamic constraints. Three numerical case studies validate the applicability of the proposed method.
Źródło:: International Journal of Applied Mathematics and Computer Science; 2018, 28, 1; 155-168
1641-876X
2083-8492
Pojawia się w:: International Journal of Applied Mathematics and Computer Science
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Recovery of Pig Iron from Copper Smelting Slag by Reduction Smelting
Autorzy:: Erdenebold, U.
Choi, M.-H.
Wang, J.-P.
Powiązania:: https://bibliotekanauki.pl/articles/355067.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: copper slag
reduction
pig iron
fayalite
recovery
Opis:: Copper slag is a by-product obtained during smelting and refining of copper. Copper smelting slag typically contains about 1 wt.% copper and 40 wt.% iron depending upon the initial ore quality and the furnace type. Main components of copper slag are iron oxide and silica. These exist in copper slag mainly in the form of fayalite (2FeO ·SiO₂ ). This study was intended to recover pig iron from the copper smelting slag by reduction smelting method. At the reaction temperature of below 1400°С the whole copper smelting slag was not smelted, and some agglomerated, showing a mass in a sponge form. The recovery behavior of pig iron from copper smelting slag increases with increasing smelting temperature and duration. The recovery rate of pig iron varied greatly depending on the reaction temperature.
Źródło:: Archives of Metallurgy and Materials; 2018, 63, 4; 1793-1798
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Fabrication of Antireflection Structures as a Protective Layer of Solar Cells with Nanoporous Silica Films and Nanoimprinted Moth-Eye Structure
Autorzy:: Kim, K.
Han, J.
Jang, J.
Choi, C.
Choi, S.
Kim, C.
Kye, H.
Cheong, I.
Powiązania:: https://bibliotekanauki.pl/articles/1492625.pdf
Data publikacji:: 2011-12
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 61.46.-w
68.37.-d
68.55.-a
78.20.-e
Opis:: The antireflection structures are fabricated by sol-gel process as a protective layer of solar cells and by hot embossing process with anodized aluminum oxide membrane template on polycarbonate film. The optical properties and morphology of the antireflection structures are analyzed by UV-visible spectroscopy and field emission scanning electron microscopy, respectively. The total conversion efficiency of a polycrystalline Si solar cell module with the protective layer, sol-gel-derived nanoporous antireflection structure, is increased by 2.6% and 5.7% for one-side antireflection coated prismatic matt glass and both-side antireflection coated prismatic matt glass, respectively.
Źródło:: Acta Physica Polonica A; 2011, 120, 6A; A-047-A-049
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Temperature Effect on the Growth Rate and Physical Characteristics of SnO2 Thin Films Grown by Atomic Layer Deposition
Autorzy:: Kim, D.
Kim, D. H.
Riu, D.-H.
Choi, B. J.
Powiązania:: https://bibliotekanauki.pl/articles/353808.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: atomic layer deposition
tin oxide
growth rate
film density
optical band gap
Opis:: Among the various thin film coating techniques, atomic layer deposition (ALD) has features of good controllability of the thickness, excellent step-coverage in 3-dimensional object even in the sub-nm thickness range at the relatively low deposition temperature. In this study, SnO₂ thin films were grown by ALD in the variation of substrate temperatures from 150 to 250°C. Even such a low temperature may influence on the growth kinetics of the ALD reaction and thus the physical characteristics of thin films, such as crystallinity, film density and optical band gap, etc. We observed the decrease of the growth rate with increasing substrate temperature, at the same time, the density of the film was decreased with increasing temperature. Steric hindrance effect of the precursor molecule was attributed to the inverse relationship of the growth temperature and growth rate as well as the film density. Optical indirect band gap energy (~3.6 eV) of the ALD-grown amorphous SnO₂ films grown at 150°C was similar with that of the literature value, while slightly lower band gap energy (~3.4 eV) was acquired at the films grown at higher temperature.
Źródło:: Archives of Metallurgy and Materials; 2018, 63, 2; 1061-1064
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Flexible pavement analysis considering temperature profile and anisotropy behavior in hot mix asphalt layer
Autorzy:: Choi, J.
Seo, Y.
Kim, S. H.
Beadles, S.
Powiązania:: https://bibliotekanauki.pl/articles/230733.pdf
Data publikacji:: 2011
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: zachowanie anizotropowe
metoda elementów skończonych
kruszywo
nawierzchnia
HMA
anisotropic behavior
finite element method
aggregate base
pavement
Opis:: A three Dimensional finite element model (FEM) incorporating the anisotropic properties and temperature profile of hot mix asphalt (HMA) pavement was developed to predict the structural responses of HMA pavement subject to heavy loads typically encountered in the field. In this study, ABAQUS was adopted to model the stress and strain relationships within the pavement structure. The results of the model were verified using data collected from the Korean Highway Corporation Test Road (KHCTR). The results demonstrated that both the base course and surface course layers follow the anisotropic behavior and the incorporation of the temperature profile throughout the pavement has a substantial effect on the pavement response predictions that impact pavement design. The results also showed that the anisotropy level of HMA and base material can be reduced to as low as 80% and 15% as a result of repeated loading, respectively.
Źródło:: Archives of Civil Engineering; 2011, 57, 4; 347-356
1230-2945
Pojawia się w:: Archives of Civil Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Variable-Focus Fluid Lens Using an Electromagnetic Actuator
Autorzy:: Lee, J.
Park, K.
Choi, J.
Kim, H.
Kong, S.
Powiązania:: https://bibliotekanauki.pl/articles/1399681.pdf
Data publikacji:: 2013-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 85.85.+j
42.79.Bh
Opis:: A variable-focus fluid lens controlled by an electromagnetic actuator and its characteristics are presented in this paper. The repulsive force between an NdFeB magnet and a solenoid through electromagnetic induction causes deflections in the elastomeric membranes integrated in the lens resulting in a focal-length change. The controllability of the focal length of the fabricated lens with an aperture size of 2 mm was approximately from infinity to 15 mm (with input current of 100 mA). The actuator including the solenoid was carefully designed to avoid thermal crosstalk of the lens fluid and magnet from the electromagnetic induction of the solenoid. The settling time to form a convex shape of the lens membrane was approximately 2.5 ms at an input current of 20 mA.
Źródło:: Acta Physica Polonica A; 2013, 123, 2; 202-204
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Reaction Kinetics and Morphological Study of TiNb2O7 Synthesized by Solid-State Reaction
Autorzy:: Choi, S. H.
Ali, B.
Choi, K. S.
Hyun, S. K.
Sim, J. J.
Choi, W. J.
Joo, W.
Lim, J. H.
Lee, T. H.
Kim, T. S.
Park, K. T.
Powiązania:: https://bibliotekanauki.pl/articles/355326.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: solid state reaction
kinetic analysis
quantitative phase analysis
TiNb2O7 synthesis
Opis:: Although TiNb₂O₇ is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb₂O₇ compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb₂O₇ phase, the starting materials, TiO₂ and Nb₂O₅ were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 2B; 1051-1056
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: Experimental Study On Fracture Property Of Double Cantilever Beam Specimen With Aluminum Foam
Doświadczalne badanie pękania mimośrodowo rozciąganej próbki z bocznym karbem wykonanej z piany aluminiowej
Autorzy:: Kim, Y. C.
Choi, H. K.
Cho, J. U.
Powiązania:: https://bibliotekanauki.pl/articles/351465.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: aluminium foam
double cantilever beam
fracture energy
adhesively bonded structure
piana aluminiowa
podwójna belka wspornikowa
energia pękania
Opis:: This study aims to investigate double cantilever beam specimen with aluminum foam bonded by spray adhesive to investigate the fracture strength of the adhesive joint experimentally. The fracture energy at opening mode is calculated by the formulae of British Engineering Standard (BS 7991) and International Standard (ISO 11343). For the static experiment, four types of specimens with the heights (h) of 25 mm, 30 mm, 35 mm and 40 mm are manufactured and the experimental results are compared with each other. As the height becomes greater, the fracture energy becomes higher. After the length of crack reaches 150 mm, the fracture energy of the specimen (h=35 mm) is greater than that of the specimen (h=40 mm). Fatigue test is also performed with DCB test specimen. As the height decreases, the fracture energy becomes higher. By the result obtained from this study, aluminum foam with adhesive joint can be applied to actual composite structure and its fracture property can possibly be anticipated.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1151-1154
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: Enhanced Microwave Absorption of CNT Composites Mixing with Fe3O4 and Carbonyl Iron
Autorzy:: Park, J. H.
Choi, J.
Lee, K.
Park, J.
Song, J. K.
Jeon, E.
Powiązania:: https://bibliotekanauki.pl/articles/351106.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: magnetic powders
complex permittivity
complex permeability
composite materials
microwave absorption
Opis:: We fabricated two different kinds of composite materials for absorbing microwave in a frequency range of 2 to 18 GHz using coaxial airline and thru-reflect-line (TRL) method. The composite materials having carbon nanotube (CNT) with carbonyl iron (CI) or iron oxide (Fe₃ O₄ ) were fabricated by mixing each components. Magnetic properties were measured by SQUID equipment. Complex permittivity and complex permeability were also obtained by measuring S-parameters of the toroidal specimen dispersing CI/CNT and Fe₃ O₄ /CNT into the 50 weight percent (wt%) epoxy resin. The real permittivity was improved by mixing the CNT however, the real permeability was same as pure magnetic powders. The CI/CNT had a maximum value of real permittivity and real permeability, 11 and 1.4 at 10 GHz, respectively. The CNT composites can be adapted to the radar absorbing materials, band width 8-12 GHz.
Źródło:: Archives of Metallurgy and Materials; 2018, 63, 3; 1513-1516
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: Oxide Formation In Metal Injection Molding Of 316L Stainless Steel
Tworzenie tlenków podczas wtryskiwania proszku stali nierdzewnej 316L
Autorzy:: Jang, J. M.
Lee, W.
Ko, S.-H.
Han, C.
Choi, H.
Powiązania:: https://bibliotekanauki.pl/articles/351352.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: powder injection molding
sintering
316L stainless steel
sintering atmosphere
micro parts
wtryskiwanie proszku
spiekanie
stal nierdzewna 316L
mikro-część
Opis:: The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1281-1285
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:: Photoluminescence Studies of Aluminum Nitride Nanowires
Autorzy:: Yang, J.
Na, H.
Kim, H.
Kebede, M.
Choi, R.
Jeong, J.
Lee, C.
Powiązania:: https://bibliotekanauki.pl/articles/1505466.pdf
Data publikacji:: 2011-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 81.07.-b
78.55.-m
Opis:: We report the production of AlN nanowires by the thermal heating method, for exploring their photoluminescence properties. The room-temperature photoluminescence properties were investigated with different annealing environment. While broad emissions with peaks at around 2.45 and 2.95 eV were obtained from both unannealed and annealed samples, the additional 2.1 eV peak was found from the annealed samples. We have suggested the possible emission mechanisms based on the assumption that both 2.45 eV peak and 2.1 eV peak are ascribed to the nitrogen vacancies. Annealing in N_2 environment exhibited lower intensities of 2.45 eV peak and 2.1 eV peak in comparison to those in Ar environment, presumably due to the suppression of nitrogen vacancies.
Źródło:: Acta Physica Polonica A; 2011, 119, 2; 125-127
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 15.

Tytuł:: Fabrication of a Spherical Titanium Powder by Combined Combustion Synthesis and DC Plasma Treatment
Autorzy:: Choi, S. H.
Ali, B.
Hyun, S. K.
Sim, J. J.
Choi, W. J.
Joo, W.
Lim, J. H.
Lee, Y. J.
Kim, T. S.
Park, K. T.
Powiązania:: https://bibliotekanauki.pl/articles/356067.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: combustion synthesis
DC plasma treatment
titanium powder
3D printing process
combustion parameters
Opis:: Combustion synthesis is capable of producing many types of refractory and ceramic materials, as well as metals, with a relatively lower cost and shorter time frame than other solid state synthetic techniques. TiO₂ with Mg as reductant were dry mixed and hand compacted into a 60 mm diameter mold and then combusted under an Ar atmosphere. Depending on the reaction parameters (Mg concentration 2 ≤ α ≤ 4), the thermocouples registered temperatures between 1160°C and 1710°C . 3 mol of Mg gave the optimum results with combustion temperature (T_c) and combustion velocity (U_c) values of 1372°C and 0.26 cm/s respectively. Furthermore, this ratio also had the lowest oxygen concentration in this study (0.8 wt%). After combustion, DC plasma treatment was carried out to spheroidize the Ti powder for use in 3D printing. The characterization of the final product was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and N/O analysis.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 2B; 1057-1062
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 16.

Tytuł:: Implementation of a Novel Audio Network Protocol
Autorzy:: Lee, J.
Jeon, H.
Choi, P.
Kwon, S.
Lee, S.
Powiązania:: https://bibliotekanauki.pl/articles/178062.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: audio mixer
AoIP
audio over internet protocol
DANTE
SR System
Opis:: Recently, the rapid advancement of the IT industry has resulted in significant changes in audio-system configurations; particularly, the audio over internet protocol (AoIP) network-based audio-transmission technology has received favourable evaluations in this field. Applying the AoIP in a certain section of the multiple-cable zone is advantageous because the installation cost is lower than that for the existing systems, and the original sound is transmitted without any distortion. The existing AoIP-based technology, however, cannot control the audio-signal characteristics of every device and can only transmit multiple audio signals through a network. In this paper, the proposed Audio Network & Control Hierarchy Over peer-to-peer (Anchor) system enables all audio equipment to send and receive signals via a data network, and the receiving device can mix the signals of different IPs. Accordingly, it was possible to improve the system-application flexibility by simplifying the audio-system configuration. The research results confirmed that the received audio signals from different IPs were received, mixed, and output without errors. It is expected that Anchor will become a standard for audio-network protocols.
Źródło:: Archives of Acoustics; 2018, 43, 4; 637-645
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 17.

Tytuł:: Differences in gait pattern between the elderly and the young during level walking under low illumination
Autorzy:: Choi, J.-S.
Kang, D.-W.
Shin, Y.-H.
Tack, G.-R.
Powiązania:: https://bibliotekanauki.pl/articles/307026.pdf
Data publikacji:: 2014
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: gait
illumination
elderly
stance ratio
toe clearance
safety margin
chód
iluminacja
wiek
palec nogi
Opis:: The purpose of this study was to compare changes in the gait pattern between the elderly and young during level (i.e., even surface) walking under low illumination. Vision during walking plays a role in avoiding obstacles and uneven surfaces, as well as an important role in the proactive control of dynamic stability and route planning for level walking. Fourteen elderly and fourteen young male subjects walked on a 7 m walkway with two illumination conditions using self-selected walking speed: walking with normal (>300 lux) and low illumination (<10 lux). Walking speed, stance phase ratio, toe clearance on swing phase, and range of motion at the center of mass were used to compare the differences in gait pattern between two illumination conditions and ages. During walking with low illumination, walking speed and stance phase ratio of the young decreased, and toe clearance of the young increased. However, there was no difference in these variables due to low illumination in the elderly subjects. Despite level walking conditions, there were some differences in gait pattern between the young and the elderly due to illumination conditions. This implies that the young showed a more positive change of gait pattern, due to low illumination, than that of the elderly. In this respect, further study is necessary to identify differences between the young and the elderly, when they walk on an uneven or obstacle walkway with low illumination.
Źródło:: Acta of Bioengineering and Biomechanics; 2014, 16, 1; 3-9
1509-409X
2450-6303
Pojawia się w:: Acta of Bioengineering and Biomechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 18.

Tytuł:: The Effect Of Grain Size On The Mechanical Properties Of Aluminum
Wpływ wielkości ziarna na właściwości mechaniczne aluminium
Autorzy:: Jeong, G.
Park, J.
Nam, S.
Shin, S.-E.
Shin, J.
Bae, D.
Choi, H.
Powiązania:: https://bibliotekanauki.pl/articles/351200.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: nanocrystalline aluminum
grain size
microstructure
mechanical properties
tensile behavior
aluminium
wielkość ziarna
mikrostruktura
rozciąganie
właściwości mechaniczne
Opis:: Although many studies have focused on the unique plastic deformation behavior of nanocrystalline aluminum (e.g., the positive deviation from Hall-Petch relation, the unusual yield-drop phenomenon in tensile mode, etc.), the data reported by different research groups are inconsistent with each other, possibly because of different fabrication processes. In this study, aluminum samples with a wide grain-size spectrum – from a few micrometers down to 100 nanometers – are manufactured by powder metallurgy. The grain size was measured by X-ray diffraction analysis and transmission electron microscope observation. Furthermore, the tensile behavior, which varied according to a grain size, is discussed with a comparison of the theoretical models.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1287-1291
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 19.

Tytuł:: An analysis on the thermal characteristics according to the viscosity of bearing lubricant and the cooling condition for the high speed motor spindle
Autorzy:: Choi, D. B.
Lee, J. J.
Kim, S. T.
Kwon, H. D.
Kim, C. Y.
Powiązania:: https://bibliotekanauki.pl/articles/1429194.pdf
Data publikacji:: 2008
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:: high speed motor spindle
thermal displacement cooling condition
lubricant viscosity
Opis:: Thermal displacement of the high speed machine tools has a large influence on machining accuracy. The high speed motor spindle with many heat sources is widely used for the high speed machine tools recently. The important problem in this spindle is to reduce and minimize the thermal effects by motor and bearings. This paper presents the analysis on thermal characteristics for high speed motor spindle system with oil-air lubricated angular contact ceramic ball bearings and built-in motor. An analysis on the thermal characteristics of spindle is performed according to the cooling conditions and the viscosity of bearing lubricants by using finite element method. This results can be applied to the design and manufacturing for the high speed motor spindle.
Źródło:: Journal of Machine Engineering; 2008, 8, 4; 88-98
1895-7595
2391-8071
Pojawia się w:: Journal of Machine Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 20.

Tytuł:: Low-velocity impact characteristics of composite plates with shape memory alloy wires
Niskoprędkościowe charakterystyki uderzeniowe płyt kompozytowych zawierających włókna ze stopów z pamięcią kształtu
Autorzy:: Rim, M.-S.
Kim, E.-H.
Lee, I.
Choi, I.-H.
Ahn, S.-M.
Koo, K.-N.
Bae, J.-S.
Roh, J.-H.
Powiązania:: https://bibliotekanauki.pl/articles/279293.pdf
Data publikacji:: 2011
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: shape memory alloy
SMAHC
composite
low-velocity impact
impact resistance
Opis:: To investigate impact characteristics of shape memory alloy hybrid com- posites (SMAHC), several experiments were performed. Tensile tests of shape memory alloy (SMA) wires were carried out to investigate thermomechanical properties, and low-velocity impact tests of SMAHC plates and conventional composite plates without SMAs at the critical energy level. low-velocity impact tests of several types of composite plates, including composite plates with embedded SMAs/Fe/Al wires and conventional composite plates, were also done. Results of these experiments show that embedding SMAs in a composite plate can improve the impact resistance. Lastly, low-velocity impact tests of SMAHC plates with SMA wires embedded at different positions through the thickness were performed in an effort to improve the impact resistance. Embedding SMA wires at a lower position in the composite plates was the most effective for improving the impact resistance.
Do analizy charakterystyk uderzeniowych hybrydowych kompozytów SMAHC zwierających włókna SMA ze stopów wykazujących efekt pamięci kształtu przeprowadzono szereg badań eksperymentalnych. Przeprowadzono próby na rozciąganie włókien SMA w celu zbadania ich właściwości termomechanicznych oraz niskoprędkościowe testy uderzeniowe płyt SMAHC oraz konwencjonalnych płyt laminowanych przy energii krytycznej. Wykonano także testy dla płyt kompozytowych zawierających włókna SMA/Fe/Al. Rezultaty doświadczeń pokazały, że wbudowanie w strukturę laminatu włókien SMA może zwiększyć odporność kompozytu na obciążenie uderzeniowe. Opisano również badania eksperymentalne płyt SMAHC z włóknami SMA wbudowanymi na różnej głębokości. Wykazano, że najlepsze parametry posiadają kompozyty z włóknami umieszczonymi możliwie daleko od uderzanej powierzchni.
Źródło:: Journal of Theoretical and Applied Mechanics; 2011, 49, 3; 841-857
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 21.

Tytuł:: Influence of InAs Coverage on Transition of Size Distribution and Optical Properties of InAs Quantum Dots
Autorzy:: Kim, G.
Jeon, S.
Cho, M.
Choi, H.
Kim, D.
Kim, M.
Kwon, Y.
Choe, J.
Kim, J.
Leem, J.
Powiązania:: https://bibliotekanauki.pl/articles/1535820.pdf
Data publikacji:: 2010-10
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 81.15.Hi
68.37.Ps
78.55.Cr
78.67.Hc
Opis:: The influence of InAs coverage on the formation of self-assembled quantum dots grown by molecular-beam epitaxy was investigated by atomic force microscopy and photoluminescence measurements. As the InAs coverage increased from 2.0 to 3.0 monolayers, the quantum dot density decreased from 1.1 × $10^{11}$ to 1.36 × $10^{10} cm^{-2}$. This result could be attributed to the coalescence of neighboring small InAs quantum dots resulting in the formation of much larger InAs quantum dots with lower quantum dot density. Atomic force microscopy results revealed that as the InAs quantum dot coverage increased, the transition of size distribution of InAs quantum dots from single-modal to multimodal occurred. The temperature-dependent photoluminescence spectra showed that the photoluminescence spectra red shifted and the photoluminescence peak intensity decreased as the InAs coverage increased. The thermal activation energy was strongly dependent on the InAs coverage, and for InAs quantum dots with 3.0 ML thick InAs coverage, this energy was estimated to be 147 meV.
Źródło:: Acta Physica Polonica A; 2010, 118, 4; 673-676
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 22.

Tytuł:: Flexible Software Design for Korean WA-DGNSS Reference Station
Autorzy:: Choi, W.S.
Chhattan, S.S.
Kye, J.E.
Han, W.Y.
Yun, H.
Kee, C.
Powiązania:: https://bibliotekanauki.pl/articles/116770.pdf
Data publikacji:: 2013
Wydawca:: Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:: Global Navigation Satellite System (GNSS)
Flexible Software Design
Wide area Reference Station (WRS)
Opis:: In this paper, we describe the software design results of WA‐DGNSS reference station that will be constructed in Korea in the near future. Software design of the WRS (Wide area Reference Station) is carried out by applying object oriented software methodology in order to provide flexibilities: easy of model change (namely ionospheric delay model etc) and system addition (Galileo, GLONASS in addition to GPS etc). Software design results include the use case diagrams for the functions to be executed, the architecture diagram showing components and their relationships, the activity diagrams of behaviors and models among them, and class diagrams describing the attribute and operation.
Źródło:: TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2013, 7, 1; 75-78
2083-6473
2083-6481
Pojawia się w:: TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 23.

Tytuł:: Effects of Grain Boundary Morphologies on Stress Corrosion Cracking of Alloy 600
Autorzy:: Kim, H. P.
Choi, M. J.
Kim, S. W.
Kim, D. J.
Lim, Y. S.
Hwang, S. S.
Powiązania:: https://bibliotekanauki.pl/articles/352569.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: alloy 600
NaOH
stress corrosion cracking
grain boundary morphologies
Opis:: Effects of grain boundary morphologies on stress corrosion cracking (SCC) of Alloy 600 have been studied in 40% NaOH at 315°C using C-ring specimens. The configuration of the grain boundary and the intergranular carbide density were controlled by heat treatment. SCC tests were performed at +150 mV above the corrosion potential. The specimen with a serrated grain boundary showed higher SCC resistance than that with a straight grain boundary. This appears to be caused by the fact that the specimen with the serrated grain boundary has longer SCC path. SCC resistance also increased with intergranular carbide density probably due to enhanced relaxation of stress at intergranular carbide.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 2B; 1415-1419
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 24.

Tytuł:: Optical Properties of Multi-Stacked InAs Quantum Dots Embedded in GaAs/InGaAs Strained Layer and its Annealing Behaviors
Autorzy:: Kim, D.
Kim, G.
Jeon, S.
Cho, M.
Choi, H.
Kim, M.
Lee, D.
Kim, J.
Eom, G.
Leem, J.
Powiązania:: https://bibliotekanauki.pl/articles/1537752.pdf
Data publikacji:: 2010-06
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 78.67.Hc
78.55.Cr
81.05.Ea
Opis:: Multi-stacked InAs QDs embedded in ten periods of GaAs/$In_{0.1}Ga_{0.9}As$ strained layers were grown by MBE and their optical properties were investigated by using PL spectroscopy. For the QDs embedded in ten periods of GaAs/$In_{0.1}Ga_{0.9}As$ strained layers, the PL intensity is enhanced about 4.7 times and a narrower FWHM of 26 meV is observed compared to those of the conventional multi-stacked QDs. The PL spectra of the InAs QDs show blue-shifts of about 50 meV with increasing annealing temperature up to 850°C. At annealing temperature of 600°C, the FWHM of the PL peak is reduced to 16 meV and PL intensity is enhanced compared to those of the as-grown sample, which indicates improvement of size uniformity and crystal quality of the QDs.
Źródło:: Acta Physica Polonica A; 2010, 117, 6; 941-944
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 25.

Tytuł:: Fabrication and Characterization of CoCrFeNiMn High Entropy Alloy Powder Processed by Gas Atomization
Autorzy:: Park, T. G.
Lee, S. H.
Lee, B.
Cho, H. M.
Choi, W. J.
Kim, B. S.
Shin, K. S.
Kim, T.-S.
Powiązania:: https://bibliotekanauki.pl/articles/353649.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: high entropy alloy
gas atomization
spark plasma sintering
CoCrFeNiMn
Opis:: In this study, precisely controlled large scale gas atomization process was applied to produce spherical and uniform shaped high entropy alloy powder. The gas atomization process was carried out to fabricate CoCrFeNiMn alloy, which was studied for high ductility and mechanical properties at low temperatures. It was confirmed that the mass scale, single phase, equiatomic, and high purity spherical high entropy alloy powder was produced by gas atomization process. The powder was sintered by spark plasma sintering process with various sintering conditions, and mechanical properties were characterized. Through this research, we have developed a mass production process of high quality and spherical high entropy alloy powder, and it is expected to expand applications of this high entropy alloy into fields such as powder injection molding and 3D printing for complex shaped components.
Źródło:: Archives of Metallurgy and Materials; 2018, 63, 2; 1055-1059
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 26.

Tytuł:: Oxidation Behavior of Steel with Cr Content and Water Flow Rate
Autorzy:: Kim, D.-J.
Kim, K. M.
Shin, J. H.
Cheong, Y. M.
Lee, E. H.
Lee, G. G.
Kim, S. W.
Kim, H. P.
Choi, M. J.
Lim, Y. S.
Hwang, S. S.
Powiązania:: https://bibliotekanauki.pl/articles/351548.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: steel
flow accelerated corrosion
Cr content
flow rate
surface oxides
Opis:: Fast water flow facilitates ferrous ion transport leading to flow accelerated corrosion (FAC) of carbon steel and the possibility of a large accident through a failure of a secondary pipe in a nuclear power plant. Ion transport is directly linked to oxide properties such as the thickness, chemical composition and porosity. This work deals with a precise observation of the cross section of the corroded specimen focusing on an oxide passivity and its thickness using SEM (scanning electron microscope) and TEM (transmission electron microscope) as well as an apparent weight loss and a surface observation for the specimens corroded using a rotating cylindrical electrode autoclave system in pure water of pH 7 at 150°C having dissolved oxygen below 1 ppb within a flow rate range of 0 to 10 m/s. The Cr content in steel was changed from 0.02 to 2.4 wt%. Increasing the Cr content in the alloy, the FAC rate and oxide thickness decreased. The oxide porosity tends to decrease with the Cr content and immersion time owing to the development of Cr containing oxide. The oxidation behavior is not changed with the immersion time.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 2B; 1383-1387
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 27.

Tytuł:: Warm Tensile Deformation Behavior and Constitutive Equation of Supersaturated Solid-Solutionized Al-9Mg Extruded Alloy
Autorzy:: Yang, Seung Y.
Kim, Bong H.
Lee, Da B.
Choi, Kweon H.
Kim, Nam S.
Ha, Seong H.
Yoon, Young O.
Lim, Hyun K.
Kim, Shae
Kim, Young J.
Powiązania:: https://bibliotekanauki.pl/articles/2048882.pdf
Data publikacji:: 2021
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: aluminum alloy
Al-9Mg alloy
tensile test
constitutive equation
Opis:: In this paper, as a purpose to apply the supersaturated solid-solutionized Al-9Mg alloy to the structural sheet parts of automotive, tensile tests were conducted under the various conditions and a constitutive equation was derived from the tensile test results. Al-9Mg alloy was produced using a special Mg master alloy containing Al2Ca during the casting process and extruded into the sheet. In order to study the deformation behavior of Al-9Mg alloy in warm temperature forming environments, tensile tests were conducted under the temperature of 373 K-573 K and the strain rate of 0.001/s~0.1/s. in addition, by using the raw data obtained from tensile tests, a constitutive equation of the Al-9Mg alloy was derived for predicting the optimized condition of the hot stamping process. Al-9Mg alloy showed uncommon deformation behavior at the 373 K and 473 K temperature conditions. The calculated curves from the constitutive equation well-matched with the measured curves from the experiments particularly under the low temperature and high strain rate conditions.
Źródło:: Archives of Metallurgy and Materials; 2021, 66, 4; 1013-1018
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 28.

Tytuł:: Carbon Co-Deposition During Gas Reduction of Water-Atomized Fe-Cr-Mo Powder
Autorzy:: Ali, B.
Choi, S. H.
Seo, S. J.
Maeng, D. Y.
Lee, C. G.
Kim, T. S.
Park, K. T.
Powiązania:: https://bibliotekanauki.pl/articles/352709.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: water atomization
Fe-based powder
oxide reduction
powder metallurgy
sinter-hardening alloys
Opis:: The water atomization of iron powder with a composition of Fe-3Cr-0.5Mo (wt.%) at 1600°C and 150 bar creates an oxide layer, which in this study was reduced using a mixture of methane (CH₄) and argon (Ar) gas. The lowest oxygen content was achieved with a 100 cc/min flow rate of CH₄, but this also resulted in a co-deposition of carbon due to the cracking of CH₄. This carbon can be used directly to create high-quality, sinter hardenable steel, thereby eliminating the need for an additional mixing step prior to sintering. An exponential relationship was found to exist between the CH₄ gas flow rate and carbon content of the powder, meaning that its composition can be easily controlled to suit a variety of different applications.
Źródło:: Archives of Metallurgy and Materials; 2017, 62, 2B; 1119-1124
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 29.

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

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