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금속분리판의 Electro Polishing 및 CrN 코팅을 통한 PEMFC 성능 향상을 위한 연구
황성택(Sung Tack Hwang),천승호(Seung Ho Cheon),송준석(Jun Seok Song),윤영훈(Younghoon Yun),김병헌(Byeong Heon Kim),장하(Xia Zhang),김대웅(Dae-Ung Kim),현덕수(Deoksu Hyon),오병수(Byeong Soo Oh) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.5-1
As an important component of a fuel cell, the bipolar plate comprises a large proportion in the fuel cell’s volume, weight and price. The bipolar plate is the most widely used; however, graphite bipolar plate is large in volume, brittle and therefore easily broken during assembling. In addition, due to its poor machinability, production costs a lot, unless mass production. Compared with the graphite bipolar plate, the metal bipolar plate has good machinability, high electric conductivity and strong mechanical strength; however, it corrodes easily and has a high contact resistance, so in order to prevent corrosion and reduce the contact resistance, the basic metal needs to be processed by use of electro polishing and coating. The water which is produced by electrochemical reactions in the fuel cell must be discharged smoothly. In this study, in order to prevent corrosion the processes of electro polishing and CrN coating were used. According to the presence or absence of these processes, the contact angles can be measured and different metal bipolar plates can be made, these plates can be used for comparing and analyzing the performance of the fuel cell.
황성택(Sung-Tack Hwang),김정대(Jun-Dae Kim),황선욱(Sun-Uk Hwang),이용구(Yong-Gu Lee) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Two-Photon Photopolymerization (2PP) is one of the effective microfabrication techniques to manufacture microparts. By utilizing tightly focused ultra-short pulse laser beam, this method can solidify a liquid photoresist at the laser focal spot. When fabricating small microparts with complex shape using this technique, it is important to have high surface quality. The surface quality is closely related to the voxel size, which is a unit polymerized volume that single laser pulse can produce. Generally the voxel size varies with several experimental parameters, i.e., laser power, laser exposure time, wavelength and characterization of voxel size by varying these parameters is an important step in 2PP microfabrication. In this paper, we investigate the optimal condition for minimum voxel size by varying the laser power and exposure time.
SWCH18A 와 SUS XM7 을 적용한 초소형 나사제작 및 물성분석에 관한 연구
나승우(Seung-Woo Ra),김인락(In-Rak Kim),황성택(Sung Tack Hwang) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.9
체결부품의 사이즈가 작아질수록 실제 접합부의 면적이 줄어들기 때문에 체결력은 감소한다. 이러한 체결부품의 체결력을 결정하는 요소는 소재(Material), 구조(Geometry), 마찰(Friction)이 있다. 본 연구에서는 체결부품의 사이즈가 줄어들면서 체결력을 향상시킬 수 있는 방법 중의 하나인 소재 변경에 대하여 연구하였다. SWCH18A 와 SUS XM7 을 적용하여 초소형 나사를 제작하였으며, 3 차원 치수 측정을 통하여 피치정밀도와 두께정밀도를 측정하였다. 비커스 경도 측정을 통하여 나사가 외부의 힘에 의해 변형에 대한 저항력을 분석하였다. 또한 파단토크 시험과 SEM 을 이용한 파단면 분석을 통해 파단특성을 분석한다. As micro screws feature reduced screw lengths and pitches, the resulting clamping force diminishes because of the reduced length of the actual joints. The elements of the clamping force are material, geometry, and friction. We studied the shrinking size of the screw and the methods to improve the clamping force by changing the material. We developed a micro screw using SWCH18A and SUS XM7 materials, and obtained the precision and thickness of the pitch through three-dimensional measurement. We also measured the external resistance of the micro screw by applying the Vicker"s hardness test and conducted a break surface analysis using a break torque test and SEM for obtaining the break characteristics.