http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
나선형 홈을 가진 벤틸레이티드 디스크 브레이크 유로 내에서의 열적 성능 해석
이대근(D.K. Lee),차윤석(Y.S. Cha),이준식(J.S. Lee),박성봉(S.B. Park),이대희(D.H. Lee) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Effects of the flow passage geometry in ventilated disc brake on thermal performance have been investigated. The heat transfer measurements in the flow passage having both flat surface and spirally grooved surface geometries inside the automobile disc brake were made. Liquid Crystal-shroud transient technique was used to measure the local heat transfer coefficients. These measured local heat transfer data were utilized to numerically predict the temperature distributions as well as thermal stresses on the disc brake. The results show that the maximum temperatures on the disc brake with spirally grooved surface are approximately 44.3% lower than those with the flat surface. Thermal stresses with spirally grooved surface in the outlet region of the flow passage are approximately 2.5 times as large as those with the flat surface.
DMFC의 GDL에서 배출되는 기포와 액적 거동의 미시적 관찰과 이론적 접근
이대근(D.K. Lee),동상근(S.K. Dong),백동현(D.H. Peck),장재혁(J.H. Jang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
In DMFC, CO₂ gas and liquid water generated by electrochemical reactions respectively in anode and cathode catalytic layers take the forms of bubbles and droplets in each GDL's and they have adverse effects on the transport of reactants to the catalytic layers. In this study, we microscopically observed that they can be trapped in each GDL's, block the reactant transports and are intermittently issued to the fluid channels after a sufficient accumulation. From experiments, it was found that the trapped shapes and issuing characteristics of the bubbles and droplets are significantly different to each other and, to explain this difference, a theoretical analysis on their physics was carried out. The analysis showed that these phenomena can be described by the surface nature, i.e. hydrophilic or hydrophobic nature of fibers constituting the GDL and what is the effect of PTFE coating of GDL conventionally conducted in DMFC on the mass transports.
물질확산층의 젖음성이 직접 메탄올 연료전지의 출력에 미치는 영향과 미세 천공을 이용한 효율향상
이대근(D.K. Lee),동상근(S.K. Dong),백동현(D.H. Peck) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
CO₂ bubble and water droplet generated respectively in anode and cathode catalytic layers of DMFC have adverse effects on the transport of methanol and air to the catalytic layers, if they are not properly exhausted from the pores of MDL and quickly detached from the surface of MDL. In this study, we experimentally tested the wettability effect of MDL on the performance of DMFC and further studied its enhancement via micro-perforation of MDLs. It was found that the attached shapes and issuing characteristics of the byproducts are significantly affected by the MDL's wettability and more power was obtained for the combination of hydrophilic anode and hydrophobic cathode MDLs. Moreover, we obseved the power enhancement via the micro-perforation by 21.3%.
이대희(D.H. Lee),차윤석(Y.S. Cha),이대근(D.K. Lee),이준식(J.S. Lee),임창율(C.Y. Lim),김영생(Y.S. Kim),배종렬(J.R. Bae) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
An innovative crankless steam engine utilizing the rack and pinion has been developed to improve the thermal efficiency of the engine. This newly developed crankless steam engine converted the thermal energy of steam to the electrical power output by way of the rack and pinion instead of the conventional crank. Straight motion due to the rack changed to the rotary motion by the pinion gear of the clutch. The crankless steam engine performance was tested with steam at 5 to 6.5 ㎏<SUB>f</SUB>/㎠ and the power output varied from 2.4 to 8.0 ㎾. It follows that the maximum efficiency of the crankless steam engine has reached 74 % when the steam inlet pressure is 6.5 ㎏<SUB>f</SUB>/㎠ and the power output is 8.0 ㎾. The maximum efficiency of this engine is more than 2 times as high as the existing conventional crank engine.
김종덕(J. D. Kim),홍석관(S. K. Hong),이경환(K. H. Lee),김미애(M. A. Kim),이대근(D. K. Lee) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
It will not be an exaggeration to say that one of the most important features of RT (Rapid Tooling) technology is to easy manufacturing complex shape of cooling channel in injection mold. That is, RT technology is hardly influenced complex shape of tool, Therefore, mold designer can optimize the position and shape of cooling channel whatever they want. In this study, we optimized cooling channel through CAE analysis to solve the problem; prototype-connector-mold applied conventional cooling channel, locally warped by internal stress. The effect of three-dimensional cooling channel was supported by simulation result. But it is impossible to produce injection mold applied three-dimensional cooling channel through machining operation. Therefore, we produced the prototype-connector-mold with three-dimensional cooling channel using Direct Metal Laser Sintering (DMLS) process, and get good-quality prototype-connector without warpage.
구리전선을 전파하는 화염에 대해 전기장 인가에 따라 발생하는 현상에 대한 연구
강민성(M. S. Kang),박순호(S. H. Park),임인권(L.I. Kwon),이대근(D. K. Lee),김승곤(S. G. Kim),곽영태(Y. T. Guahk),권오붕(O. B. Kwon),박정(J. Park),정석호(S. H. Chung) 한국연소학회 2019 KOSCOSYMPOSIUM논문집 Vol.2019 No.11
An Experimental study on effect of AC electric fields on flame spread over electrical wire with a copper (Cu) metal insulated by Polyethylene (PE) was conducted with applying AC electric fields in a single-electrode configuration. The size, inclination, and shape o f s pr eading f lame as well as the dynamic behavior of molten PE were influenced appreciably by ionic wind effect when AC electric field is applied to wire, there by modifying FSR.