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하흥용 한밭대학교 에너지청정기술연구소 2003 에너지청정기술논문집 Vol.3 No.1
연료전지의 원리가 발견된 것은 100년 전이지만 최근 들어 갑자기 언론의 주목을 받기 시작하고 있는데, 이것은 연료전지 관련기술의 발달로 인해 연료전지가 일반 소비자가 사용 가능한 영역으로 접근하고 있기 때문이다. 즉, 현재 전 세계 유수의 연구기관과 기업체에서 발전용, 자동차용, 휴대용 전원 등으로 사용하기 위한 연구가 활발히 진행되고 있으며, 수년 내에 상용 제품이 출시될 것으로 예상되고 있다. 휴대용 연료전지는 휴대폰이나 PDA 등과 같은 이동통신기기의 사용이 폭증하면서 기존의 소형 배터리가 갖고 있는 여러 가지 단점을 해결해 줄 수 있는 대안으로 떠오르고 있다. 본 고는 이러한 휴대용 연료전지의 원리, 응용분야, 개발동향 등에 대해 정리한 것이다.
직접메탄올 연료전지의 장기운전특성 분석 및 성능향상 연구
하흥용,임태훈,이현숙,배병찬,이재영 한국수소및신에너지학회 2005 한국수소 및 신에너지학회논문집 Vol.16 No.1
Direct methanol fuel cell (DMFC) is considered as a candidate for portable power sources, that could overcome the disadvantages of lithium battery. But in order to attain commercial viability the long term stability of the DMFC should be achieved. Understanding the long-term behavior of membrane-electrode assembly (MEA) is a prerequisite to this purpose and the optimization of the MEA is also needed. In this study we have investigated the changes in performance and electrochemical properties of the MEA during extended operation and the effects of heat treatment of MEA on the long-term performance. The MEAs have been treated in an autoclave with saturated water vapor at 120 , vacuum oven at 140 and boiling in organic solvents. The autoclaved MEA was found to be have the best long term performance. The on-off operation mode also increased the performance probably due to effective removal of products from the electrodes. Physical and electrochemical analyses using a scanning electron microscope, impedance analyser and half-cell technique have been done to characterize the MEAs.
솔 - 젤 법으로 제조한 금속 담지 타이타니아 광촉매의 액상반응 특성
하흥용,Marc A . Anderson ( Heung Yong Ha ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.3
TiO₂ catalysts supported on stainless steel plates were prepared by using either a spin-coating or a dip-coating method and tested for the photocatalytic degradation of formic acid in an aqueous solution. During the photodegradation reaction, the oxidized surface of the metallic support was reduced and bleached. The XRD patterns of the supported TiO₂ catalysts which were fired at temperatures up to 600℃ showed that all of the TiO₂ films had only an anatase structure, and the particle size increased as the firing temperature increased. The activity of the catalyst decreased with an increase in firing temperature, which implies a nearly linear relationship of the activity with the BET surface area of the TiO₂ catalyst. When the catalyst was coated on both side of the support plate, it appeared that total reaction rates increased as much as 2 times compared to those of the one-side-coated catalysts, even though UV light was illuminated only on one side of the catalyst plate in both cases. The activities of the catalysts were not affected by the coating methods employed.
유기금속 화학증착법으로 제조한 실리카 - 타이타니아 복합막의 기체분리 특성 연구
하흥용,남석우,홍성안 ( Heung Yong Ha,Suk Woo Nam,Seong Ahn Hong ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.5
Thin films of TiO₂, SiO₂ and TiO₂/SiO₂ were deposited on the inner surface of the porous glass support tubes by the decomposition of tetraisopropyl titanate(TIPT) and tetraethyl orthosilicate(TEOS) at an atmospheric pressure. The hydrogen selectivities of the membranes were increased by the deposition of thin films of metal oxides. Deposition rate of the films and gas(H₂ or N₂) permeation properties of the membranes were much different from one another depending on the types of thin films and deposition conditions such as temperature and TIPT/TEOS ratio in the feed stream. The pure TiO₂ films which were deposited only in the temperature range between 230 and 300℃ were found to have some hydrogen selectivities. In comparison to the pure TiO₂, films, stable SiO₂ films were formed at temperatures as high as 600℃, and they showed very high hydrogen selectivities larger than 500 though their deposition rates were much slower than those of the TiO₂, films. On the other hand, composite TiO₂/SiO₂ films could he also formed at temperatures as high as 600℃ and they showed excellent hydrogen selectivities which were comparable to those of the pure SiO₂ films. And the deposition rates of TiO₂/SiO₂ films were much faster than those of the pure SiO₂ films. Gas permeation rates through the porous support decreased with increasing temperature, suggesting an Knudsen diffusion mechanism, but the film-coated membranes showed an activated diffusion process by which gas permeation rates through the membranes increased with an increase in temperature.