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고분자 전해질형 연료전지용 Au-PTFE/Al 금속분리판 연구
유승을(Yoo, Seung-Eul),김명환(Kim, Myong-Hwan),구영모(Goo, Young-Mo) 한국신재생에너지학회 2007 신재생에너지 Vol.3 No.1
Aluminum was used as metallic bipolar plate material to reduce a stack weight. The functional materials such as conductive material, Au and nonconductive material, PTFE [polytetrafluoroethylene] were coated on the bipolar plate to enhance electrical contact and corrosion prevention in PEMFC. The active area of bipolar plate is divided into the top layer part that electric current mainly passes, and the bottom layer part that gas and water pass. The bottom layer part in the flow channel needs not to have electrical conductivity because it doesn't pass electric current directly. In this reason, Au on the top layer and PTFE on the bottom layer were coated to apply high electrical conductivity and/or good corrosion resistance. Although the single cell performance using Au-PTFE/Al bipolar plate was shown 78% in comparison with that of graphite, specific power of Au-PTFE/Al bipolar plate(0.4 W/g) was twice as much as graphite bipolar plate.
유승을(Yoo, Seung-Eul),구영모(Goo, Young-Mo),김명환(Kim, Myoung-Hwan),손익제(Son, Ik-Jae),윤종진(Yoon, Jong-Jin),오승찬(Oh, Seung-Chan) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
연료전지의 상용화 시점에 이르러 내구성에 대한 기술 확보가 점점 더 부각되고 있다. 현재 연료전지의 내구성을 감소시키는 1차적인 요인은 핵심부품인 촉매, 전해질막, MEA(Membrane & Electrode Assembly) 등에 의한 것이며 2차적인 요인은 운전 시스템 및 환경 등에 의해 결정되어진다. 특히, 연료전지자동차는 이동용, 가정용, 발전용에 비하여 부하변동이 극심한 조건에서 운전되기 때문에 연료전지 시스템의 내구성 확보에 많은 제어기술이 요구된다. 본 연구에서는 연료전지자동차 운전조건(Driving mode)을 부하변동 기준에 의한 고전류, 중전류, 저전류의 3가지 모드로 분류하였다. 각각의 운전조건에서 일정 cycle마다 성능곡선을 측정하여 10만 cycle 이상의 반복운전을 수행하였으며 측정된 성능곡선을 empirical equation에 적용하여 시간에 따른 overvoltage 인자에 대한 분석을 하였다. 운전시간이 증가함에 따라 고전류 모드의 경우 activation overvoltage 인자 중 current density loss가 증가하여 OCV가 급격히 감소하였으나 내구성은 저전류 모드에 비하여 높게 나타났다. 저전류 모드의 경우 고전류 모드와 상반된 결과를 보였으며 성능감소요인은 activation 및 ohmic overvoltage의 점차적인 증가에 의한 것으로 분석되었다.
플라즈마 용사에 의한 AlSi-Al$_2$O$_3$ 복합재료 코팅층의 미세조직 및 마찰.마모특성
민준원,유승을,김영정,서동수,Min Joon-Won,Yoo Seung-Eul,Kim Young-Jung,Suhr Dong-Soo 대한용접접합학회 2004 대한용접·접합학회지 Vol.22 No.5
AlSi-Al$_2$O$_3$ composite layer was prepared by plasma spray on steel substrate. The composite powder for plasma spray was prepared by simple mechanical blending. The wear resistance of the composite layers and matrix aluminum alloy were performed in terms of size distribution of ceramic particles. Friction coefficients of AlSi were decreased with incorporation of $Al_2$O$_3$. The tribological properties of coated layers were affected by the size of incorporated $Al_2$O$_3$ particle. The reinforcement of $Al_2$O$_3$ particle into aluminum alloy matrix decreased the friction coefficient as well as wear loss.
자동차 내장부품용 나노복합재료의 난연성 및 내구내열성 향상 연구
정선경(Sun Kyoung Jeoung),유승을(Seung Eul Yoo),이평찬(Pyoung-Chan Lee),곽성복(Sung Bok Kwak),남재도(Jae-Do Nam),이기윤(Kee Yoon Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Polypropylene(PP) is one of the most widely used polyolefins, not only because of its balance of physical and mechanical properties but also because of its recycling ability and low cost. However, the ability for PP to be used ad an engineering thermoplastic is still limited by its poor mechanical properties and thermal resistance, in particular impact resistance, modulus and flame retardment. Therefore, it is expected that the simultaneous incorporation of an elastomeric phase and a rigid phase(organoclay) could lead to an attractive material with simultaneous enhancements in impact resistance and modulus relative to the neat PP. The purpose of this study is to examine the mechanical properties and flame retardment of PP reinforced with an organoclay and toughened with an elastomer made by melt processing. To promote exfoliation of clay platelets in PP, a polypropylene-grafted-maleic anhydride(MPP) material is premixed with the organoclay prior to melt processing. The mechanical properties and flame retardment of PP/clay nanocomposites depend stronglretn the change in the ratio of PP/clay, PP/elastomer, and PP/flame retardant. The PP/clay nanocomposites provided a 52%, 13%, and 48% reduction of the Max-heat release rates, total heat release, and effective heat of combustion, in spite of 33% increment of time to ignition compared with the pristine PP.