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적층 평판형 SOFC 모듈에서 소결 시 전해질 층의 휨 현상
오민욱,구신일,신효순,여동훈,Oh, Min-Wook,Gu, Sin-Il,Shin, Hyo-Soon,Yeo, Dong-Hun 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.3
A layered planer SOFC module was designed from planar-type SOFC. It was prepared by multi-layered ceramic technology. To form the cathode and the anode in the layered structure, reliable channels should be made on the both side of electrolyte perpendicularly. However, monolithic SOFC using multi-layered ceramic technology hasn't been studied another group, and the warpage of electrolyte in the channel, also, hasn't been studied, when electrode is printed on the electrolyte. In this study, the channels are prepared with electrode printing, and their warpage are evaluated. In the case of YSZ without electrode, the warpages are nothing in the limit of measurement using optical microscope. The warpage of 'YSZ-NiO printed' increases than that of 'NiO printed', and also, the case of 'double electrode printed' is similar to 'YSZ-NiO printed'. It is thought that, in the printed electrolyte, the warpage is related to the difference of the sintering behavior of each material.
Min-Wook Oh(오민욱) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Despite the fact that research into most high-performance thermoelectric (TE) materials is focused on tellurides, compelling demand has arisen to replace tellurium (Te) with selenium (Se) due to the scarcity of Te. Silver bismuth diselenide (AgBiSe<sub>2</sub>, ABS) has been widely studied in relation to thermoelectric applications due to its intrinsically low thermal conductivity. However, its low power factor (PF) has been considered as an underlying issue preventing improvements of the TE properties of ABS. Here, it is demonstrated that a high PF can be achieved by incorporating Cu into the ABS system via the nestification of conduction bands when a disordering between Ag and Bi occurs. Degenerate electronic bands simultaneously increase the density-of-states effective mass and carrier concentration while not reducing the carrier mobility significantly. Therefore, improved TE performance with a maximum PF of 8.2 μW cm<sup>-1</sup> K<sup>-2</sup> and a peak zT value of 1.14 was achieved at 773 K, opening a new horizon for the development of environmentally benign TE materials with high performance capabilities.
Si의 조성변화가 Al이 첨가된 ReSi(1.75) 단결정의 열전특성에 미치는 효과
오민욱 ( Min Wook Oh ),김민철 ( Min Chul Kim ),오명훈 ( Myung Hoon Oh ),위당문 ( Dang Moon Wee ),( Haruyuki Inui ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.6
The thermoelectric properties of ReSi(1.73+x)Al(0.02) (-0.02 < × < 0.04) have been investigated in the temperature range between 323 and 1073 K. As a result of Al-addition, the electrical properties of the ternary at low temperatures are changed from the character of nondegenerate semiconductors, which is of binary ReSi(1.75), to that of degenerate semiconductors, and the band-gap along [001] becomes wider than that of the binary. The variation of Si composition affects the electrical properties along [100], but those along [001] are conserved. The change of the band structure due to the variation of Si composition is estimated with the result of the Seebeck coefficient at low and high temperatures. The maximum dimensionless figure of merit (ZT) along [100] is about 0.7 in the temperature between 473 and 773 K and along [001] is 0.67 at 1073 K.
제일원리 계산을 이용한 rutile-TiO2의 전자구조 및 X-ray absorption spectra
오민욱 ( Min Wook Oh ),강태구 ( Tae Gu Kang ),류병기 ( Byung Ki Ryu ),이지은 ( Ji Eun Lee ),주성재 ( Sung Jae Joo ),김봉서 ( Bong Seo Kim ),민복기 ( Bok Ki Min ),이희웅 ( Hee Woong Lee ),박수동 ( Su Dong Park ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.12
Electronic structures and X-ray absorption spectra of rutile TiO2 were obtained with the first- principles calculation. Density of states, charge density and differential charge density were obtained, from which charge transfer characteristics between Ti and O was well confirmed. Direct and indirect band gap of 1.99 and 2.03 eV were evaluated, respectively. X-ray absorption spectra of rutile TiO2 was also calculated, in which the gap between main peaks was comparable with experiment. From band structure calculations, anisotropic electrical transport properties were expected, which was in good agreement with experiment.
소각로 중온 폐열 재활용 위한 복식형 열전발전시스템 개발
박수동(Park, Su-Dong),김봉서(Kim, Bong-Sea),오민욱(Oh, Min-Wook),민복기(Min, Bok-Kee),이희웅(Lee, Hee-Woong) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
소각로를 포함한 다양한 산업설비의 배폐열은 열병합 등의 다양한 방법을 통해 재활용되고 있으나 에너지의 효율적 사용과 편의성을 고려할 때, 단순한 온수공급 등의 방법보다는 전력으로서의 재활용이 매우 필요하다. 특히 재활용이 어려운 400?C이내의 중저온급 폐열원을 발전할 수 있는 유력한 방안으로 열전발전기술이 최근 부각되고 있다. 열전발전은 발전모듈의 변환효율이 7~10%이고, 시스템 효율은 5%내외로 증기발전에 비해서는 낮지만 기계적 가동부분이 없어 고장발생이 적고 기동정지가 용이하며 열이 있으면 바로 발전이 가능한 차세대 친환경 발전기술이다. 본 연구에서는 현재까지 시도, 개발되지 못한 100?C에서 400?C내외 온도영역인 중저온급 소각폐열 회수를 위한 목적으로 중온용 열전발전소재 및 모듈과 저온과 중온에 각기 대응하여 폐열발전의 효용성을 높인 복식열전발전시스템을 개발 중에 있다. 본 고에서는 현재까지 진행된 일부 연구내용들을 소개하고자 하였다.
Al-Ti-Cr 합금계 L1_2기지 합금의 800℃에서의 상안정성
오민욱,이재경,오명훈,위당문 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.1
Relationship between the phase stability and the composition of L1_2-based Ti-Al-Cr alloys at 800℃ was investigated. It was found that the yield strength of Al-21Ti-23Cr and Al-21Ti-15Cr alloys with Ti-lean composition after exposure at 800℃showed a relatively small increase compared with that of alloys homogenized at 1150℃. However, yield strength of al-30Ti-15Cr alloy with Ti-rich composition after exposure at 800℃ increased very remarkably. The difference in strength increment after exposure at 800℃ was due to the partial decomposition of L1_2 phase in Al-21Ti-23Cr and Al-21Ti-15Cr alloys, and the complete decomposition of L1_2 phase in al-30Ti-15Cr alloy. Therefore, alloys with Ti-lean composition were expected more suitable for light heat resistant and oxidation resistant coating material with respect to stability of L1_2 phase. It was also revealed that the phase decomposition of L1_2 phase resulted from the shift of L1_2 phase region to Al-rich corner in Al-Ti-Cr phase diagram with decreasing temperature.