Autor: Choi, C. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

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: 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:: A study on the development of a new grinding processes for high-lead ball screw nuts
Autorzy:: Choi, Ch.
Ha, Y.
Kim, H.
Lee, C.
Powiązania:: https://bibliotekanauki.pl/articles/99599.pdf
Data publikacji:: 2010
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:: high-lead ball screw nuts
new grinding process
surface roughness
Opis:: This paper proposes a method that machines the race of high-lead ball screw nuts, which is difficult to machine using the existing geometrical machining method, without any interferences and changes in its load rating in order to perform the high-speed in ball screws. This study calculates the inclination angle of the axis of the grinding stone for avoiding the contact of the axis to the inner diamete of the nut and determines the shape of the grinding stone through changing the inclination angle and dressing curvature determined in a dressing device Then, the grinding condition will be determined by measuring the shape meter of the screw race for solving the problem. Also, the surface roughness of the grinded surface was measured using a surface roughness tester, and check with applying a grinding process of product not being high-lead ball screw.
Źródło:: Journal of Machine Engineering; 2010, 10, 1; 50-57
1895-7595
2391-8071
Pojawia się w:: Journal of Machine Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

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: 5.

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: 6.

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: 7.

Tytuł:: Korean WA-DGNSS User Segment Software Design
Autorzy:: Shah, S. T.
Choi, W.S.
Han, W.Y.
Yun, H.
Kee, C.
Powiązania:: https://bibliotekanauki.pl/articles/116066.pdf
Data publikacji:: 2013
Wydawca:: Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:: global navigation satellite system (GNSS)
Global Positioning System GPS
User Segment
GPS Data Processing Classes
Opis:: Korean WA‐DGNSS is a large scale research project funded by Ministry of Land, Transport and Maritime Affairs Korea. It aims to augment the Global Navigation Satellite System by broadcasting additional signals from geostationary satellites and providing differential correction messages and integrity data for the GNSS satellites. The project is being carried out by a consortium of universities and research institutes. The research team at Electronics and Telecommunications Research Institute is involved in design and development of data processing softwares for wide area reference station and user segment. This paper focuses on user segment software design. Korean WA‐DGNSS user segment software is designed to perform several functions such as calculation of pseudorange, ionosphere and troposphere delays, application of fast and slow correction messages, and data verification. It is based on a layered architecture that provides a model to develop flexible and reusable software and is divided into several independent, interchangeable and reusable components to reduce complexity and maintenance cost. The current version is designed to collect and process GPS and WADGNSS data however it is flexible to accommodate future GNSS systems such as GLONASS and Galileo.
Źródło:: TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2013, 7, 1; 69-74
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: 8.

Tytuł:: Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder
Dwuetapowe spiekanie mikrosferycznych nanocząstek proszku 316L
Autorzy:: Jeon, B.
Sohn, S. H.
Lee, W.
Han, C.
Kim, Y. D.
Choi, H.
Powiązania:: https://bibliotekanauki.pl/articles/355221.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: 316L stainless steel
nanoparticle dispersed micro-sphere
pulse wire explosion
sintering
stal nierdzewna 316L
spiekanie dwuetapowe
mikrosferyczne nanocząstki
Opis:: 316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1155-1158
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

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: 10.

Tytuł:: High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap
Wytwarzanie wysokiej czystości sferycznych cząstek wolframu z twardego złomu WC-Co
Autorzy:: Han, C.
Na, H.
Choi, H.
Kim, Y.
Powiązania:: https://bibliotekanauki.pl/articles/351951.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: WC-Co
spent hard scrap
hydrometallurgy
RF thermal plasma
twardy złom
hydrometalurgia
plazma termiczna
Opis:: Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungsten carbide-cobalt hard metal scrap was mechanically broken into particles and then tungsten trioxide particle was recovered by hydrometallurgical method. Recovered tungsten trioxide was reduced to tungsten particle in a hydrogen environment. After that, tungsten particle was melted and solidified to make a spherical one by RF (Ratio Frequency) thermal plasma process. Well spherical tungsten micro-particle was successfully obtained from spent scrap. In addition to the morphological change, thermal plasma process showed an advantage for the purification of feedstock particle.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1507-1509
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

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: 12.

Tytuł:: Recovery Of Valuable Metals In Tin-Based Anodic Slimes By Carbothermic Reaction
Odzysk cennych metali ze szlamów anodowych na bazie Sn metodą reakcji karbotermicznej
Autorzy:: Han, C.
Kim, Y.-M.
Son, S. H.
Choi, H.
Kim, T. B.
Kim, Y. H.
Powiązania:: https://bibliotekanauki.pl/articles/352796.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: tin
anodic slime
carbothermic reduction
carbon
recovery
cyna
szlam anodowy
reakcja karbotermiczna
węgiel
odzysk metali
Opis:: This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973^~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail of carbothermic reaction, thermodynamic calculation was carried out and compared with experiments. From thermodynamic calculation and experiment, it was confirmed that Sn-based anodic slime could be reduced by controlling temperature and amount of carbon. However, any tendency between the reduction temperature and carbon content for the reduction reaction was not observed.
Źródło:: Archives of Metallurgy and Materials; 2015, 60, 2B; 1213-1216
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: Product recall policies and their improvement in Korea
Autorzy:: Huh, K.
Choi, C.
Powiązania:: https://bibliotekanauki.pl/articles/406905.pdf
Data publikacji:: 2016
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: product quality
product recall
product safety
recall information
recall policy
Opis:: This article aims to investigate recall policies for product safety in Korea and make suggestions for future improvements. Problematic issues in current recall policies are reviewed and analyzed. Based on survey results and previous studies, this article discusses the consumer perception of a recall. Consumers tend to regard a recall as a signal of poor quality. Furthermore, regulatory differences and weak penalties remain as obstacles to improving the recall system. Suggestions for the betterment of recall policies are derived from consultations with an expert panel and the application of other appropriate methods. At first, despite an increasing number of recall cases in Korea, it turns out that consumers are not highly sensitive to recalls, although their perceptions are mostly negative. Secondly, regulatory inconsistencies and difference problems are primarily attributable to the existence of many separate rules and regulations by product category. Thirdly, the information concerning recalls is limited, which creates an inefficient environment in which manufacturers are reluctant to voluntarily recall a defective product and consumer participation rates are too low. Therefore, the government should induce consumers to have more positive perceptions of recalls whilst concurrently reinforcing the related rules and regulations in accordance with international standards.
Źródło:: Management and Production Engineering Review; 2016, 7, 4; 39-47
2080-8208
2082-1344
Pojawia się w:: Management and Production Engineering Review
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

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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