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승용차 후미형상이 공력특성에 미치는 영향력에 관한 연구
김대훈(D.H.Kim),장진혁(J.H.Chang),고주헌(J.H.Ko) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
This investigation is aim to find a trend of drag and rear lift coefficient with hmc reference model. We investigated the aerodynamic characteristics of the rear shapes of passenger car. The rear shape consists of three configurations which including slope of rear glass, trunk lid height and rear orerhang length. From this study, we can determine the optimum dimension of rear shape with which satisfies the aerodynamic performances. Results will give a good knowledge to aerodynamic engineers for passenger car. There are three distinct results to other studies. Two configurations, the slope of rear glass and trunk lid height, are main parts for reduction of drag coefficient.And to reduce the lift coefficiedt, it can be achieved by change of trunk lid height. Drag coefficients increase with a increase of trunk lid height in the lower slope of rear glass and vice versa. We develope a program of aerodynamc optimization for the basic dimension of rear shape that is very useful to determine the direction of test procedure and to give a good guide to design criteria for new car development.<br/>
[차량운동성능부문] 풍동에서 횡풍 안정성의 시험방법론과 공력의 영향력
김대훈(D.H. Kim),이강덕(K.D. Ih),이명한(M.H. Lee) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It was investigated to analyze on cross-wind stability in full-scale wind tunnel. Some aerodynamic factors regarded the stability previous studies. front and rear lift had to consider assessing of stability as well as other aerodynamic forces. lift can change the vehicle center of gravity and weight simultaneously. And it was found that the effective method of analysis in cross-wind stability by means of wind tunnel test. This method provides some directions of stability improvement in aerodynamic styling concept and vehicle dynamic system.
[차량운동성능부문] 솔라카 차체 형상의 공력특성에 관한 연구
김대훈(D.H. Kim),김건석(G.S. Kim),박형건(H.G. Park) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It was carried out to assess the aerodynamic characteristics of l/5-scale solar car. Forces and moments acting on the model were used to estimate the driving resistance and stability under cross-wind. Drag coefficient decreased as yaw angle but lift coefficient increased. When yawed condition, yawing moment increased rapidly and it will cause unstable of steering and driving. Body unstable will be arisen from high yawing moment and rolling moment. This body had a behavior of very unstable under certain yaw range. It showed the optimum region of air extract hole from the distribution of pressure on the upper and lower surfaces. It is important to determine this hole location viewed in a driving comfort. In addition to, pressure maps inform of cooling flow over solar cells to enhance cell's power generation.
은(Ag)계 활성금속을 사용한 질화 알미늄(AlN)과 Cu의 브레이징
허대,김대훈,천병선,Huh, D.,Kim, D.H.,Chun, B.S. 대한용접접합학회 1995 대한용접·접합학회지 Vol.13 No.3
Aluminium nitride(AlN) is currently under investigation as potential candidate for replacing alumium oxide(Al$_{2}$ $O_{3}$) as a substrate material for for electronic circuit packaging. Brazing of aluminium nitride(AlN) to Cu with Ag base active alloy containing Ti has been investigated in vacuum. Binary Ag$_{98}$ $Ti_{2}$(AT) and ternary At-1wt.%Al(ATA), AT-1wt.%Ni(ATN), AT-1wt.% Mn(ATM) alloys showed good wettability to AlN and led to the development of strong bond between brate alloy and AlN ceramic. The reaction between AlN and the melted brazing alloys resulted in the formation of continuous TiN layers at the AlN side iterface. This reaction layer was found to increase by increase by increasing brazing time and temperature for all filler metals. The bond strength, measured by 4-point bend test, was increased with bonding temperature and showed maximum value and then decreased with temperature. It might be concluded that optimum thickness of the reaction layer was existed for maximum bond strength. The joint brazed at 900.deg.C for 1800sec using binary AT alloy fractured at the maximum load of 35kgf which is the highest value measured in this work. The failure of this joint was initiated at the interface between AlN and TiN layer and then proceeded alternately through the interior of the reaction layer and AlN ceramic itself.
서동남(D.N. Seo),엄유식(Y.S. Um),박경만(K.M. Park),이상재(S.J. Lee),김대훈(D.H. Kim),권영철(Y.C. Kwon) 대한설비공학회 2008 대한설비공학회 학술발표대회논문집 Vol.2008 No.2
In the present study, the cooling performances of the air-conditioner applied the fin-tube and aluminum PF heat exchangers have been experimentally investigated by using the calorimeter. The experiment is carried out in the conditions of the standard temperature and the low temperature. Fin type of PF heat exchanger is a triangler and squarer form. PF heat exchanger has smaller refrigerant weight and larger capacity and COP than the fin-tube heat exchanger. The performance of PF-2 heat exchanger with the squarer fin is more excellent than that of PF-1 heat exchanger with the triangler fin. The high pressure of PF heat exchanger decreases about 7%, compared to the fin-tube heat exchanger. Also, CSPF of the fin-tube and PF heat exchanger is evaluated.
PWM압축기를 이용한 시스템에어컨의 난방운전 시 압축기 토출온도 상관식
이상헌(S.H. Lee),권영철(Y.C. Kwon),장근선(K.S. Chang),허삼행(S.H. Heo),김대훈(D.H. Kim),윤백(B. Youn) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6
An experimental study has been performed to investigate the correlation on compressor discharge temperature of system A/C in heating mode. Indoor and outdoor temperatures, the heating capacity, compressor discharge temperature and loading time are measured by the psychrometric calorimeter. The system is controlled by applying the scroll compressor, which is operated by PWM valve and loading duty. With increasing outdoor temperature, the heating capacity increases. With increasing indoor temperature, it decreases. Also, with increasing loading duty the heating capacity increases. According to the increase in outdoor temperature and loading duty, compressor discharge temperature increases. From these experimental data, the correlation on compressor discharge temperature is proposed. It is expressed as a function of indoor temperature, outdoor temperature, and loading duty. The correlation obtained from the present study is agreed with the experimental data within 2℃.