http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
전산유체해석을 이용한 자동차용 AQS 시스템의 유로구조 설계
최종필,김병희,최우석,김시동,민준원,유승을 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
In recent years, concern among car users about air quality inside car cabins has been steadily increasing. A vehicle exhaust gases such as carbon monoxide(CO) and nitrogen oxides(NOx) entering the cabin not only reduce the quality of experience for everyone in the car, but are also harmful to the health. Therefore, an air quality sensor(AQS) system which can perform this function is issued. In this paper, the design of channel structure for automotive AQS system was studied by computational fluid dynamic analysis according to the design parameters such as the number of air inlet, membrane porosity and permeability. Form simulation results, the AQS system was developed and the performance test was conducted.
Yoo, Roh-Eul,Yun, Tae Jin,Rhim, Jung Hyo,Yoon, Byung-Woo,Kang, Koung Mi,Choi, Seung Hong,Kim, Ji-Hoon,Kim, Jeong Eun,Kang, Hyun-Seung,Sohn, Chul-Ho,Han, Moon Hee American Heart Association, Inc. 2015 Stroke Vol.46 No.2
<P><B>Background and Purpose—</B></P><P>The purpose of this study was to evaluate whether bright vessel appearance on arterial spin labeling (ASL) MRI can help localize arterial occlusion sites in patients with acute ischemic stroke.</P><P><B>Methods—</B></P><P>Patients who underwent MRI for suspected acute ischemic stroke, as identified by an area of restricted diffusion, were included. All images were visually analyzed for the presence or absence of (1) arterial occlusion on time-of-flight MR angiography, (2) bright vessel appearance on ASL images, and (3) susceptibility vessel sign. McNemar 2-tailed test was used to compare the sensitivities of ASL and susceptibility-weighted imaging for the detection of arterial occlusion, using MR angiography as the reference standard.</P><P><B>Results—</B></P><P>ASL bright vessel appearance was significantly more common in the group with occlusion than in the group without occlusion (94% [33 of 35] versus 21% [17 of 82], respectively; <I>P</I><0.001). The bright vessel appearance, when present, was seen proximal or distal to the occlusion site. The bright vessel appearance had a significantly higher sensitivity for the detection of occlusion than the susceptibility vessel sign (94% [33 of 35] versus 66% [23 of 35], respectively; <I>P</I>=0.002). In cases with negative MR angiography, the bright vessel appearance helped identify more additional arterial occlusions than the susceptibility vessel sign (21% [17 of 82] versus 10% [8 of 82], respectively; <I>P</I>=0.012).</P><P><B>Conclusions—</B></P><P>The bright vessel appearance on ASL imaging can provide an important diagnostic clue for the detection and localization of arterial occlusion sites in patients with acute ischemic stroke.</P>
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.