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이장희(J. H. Lee),김태권(T. K. Kim),최인수(I. S. Choi) 한국자동차공학회 1994 한국 자동차공학회논문집 Vol.2 No.4
An experimental investigation was undertaken in a diesel spray to evaluate wall impingement behavior and droplet size distribution. Emphasis is placed on the possibility of the application for new combustion type which is based on OSKA-D type. Visualization were employed using optical scheme which was a spark shadowgraphy to observe the behavior of wall impingement caused by diesel spray vertically injected at the center of the combustion chamber. Droplet size measurements using Malvern system were made to quantify the visual observations with the surface diameter of impingement. The effects of the surface dia. variation on the droplet size during injection with the wall impingement spray are discussed. It was found that for the wall impingement spray the droplet size becomes greatly small rather than the spray without the wall impingement and the droplet deposition rate of the injection fuel is decreased as the surface area of impingement becomes small.<br/>
이상적 변형이론을 이용한 박판 초기형상 설계에 관한 연구
박상후(S.H.Park),이동우(D.W.Lee),양동열(D.Y.Yang),김용환(Y.H.Kim),이장희(J.H.Lee) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_1
A new blank design method is introduced to predict the blank shape and the strain distribution in the sheet metal forming process. This method deals with only one step from the final shape to the initial blank using the ideal forming theory. Based on this theory. a three-dimensional membrane finite element code has been developed for ideal sheet forming. In this paper. the designs of initial blanks for forming a cylindrical cup. a rectangular Clip. and a front fender are presented as examples. Also. it compares the two shapes. the final shape with the shape which is deformed from the initial blank using the FEM analysis code.<br/> The results illustrate the information that this. direct design code is useful in the preliminary design state.<br/>
이상적 변형이론을 이용한 박판 초기형상 설계에 관한 연구
박상후(S. H. Park),윤정환(J. W. Yoon),양동열(D. Y. Yang),김용환(Y. H. Kim),이장희(J. H. Lee) 한국자동차공학회 1997 한국 자동차공학회논문집 Vol.5 No.4
A new blank design method is introduced to predict the blank shape and the strain distribution in the sheet metal forming process. This method deals with only one step from the final shape to the initial blank using the ideal fanning theory. Based on this theory, a three-dimensional membrane finite element code has been developed to design an initial blank in the sheet metal fanning process. In this paper, the designs of initial blanks for forming a cylindrical cup, a rectangular cup, and a front fender are presented as examples. Also, it compares the two shapes, the target shape with the shape which is deformed from the initial blank using the FEM analysis code.<br/> The results illustrate the information that this direct design code is useful in the preliminary design state.<br/>
한국재래산양에서 계절이 정소기능, 정자의 내동성 및 수정능력에 미치는 영향 I. 정액성상과 정자의 내동성 및 난자침입능력의 계절적 변화
김창근,정영채,김광식,윤종택,이장희,정영호,최선호,김흥률,김수,권처진,Kim, C.K.,Chung, Y.C.,Kim, K.S.,Yoon, J.T.,Lee, J.H.,Chung, Y.H.,Choi, S.H.,Kim, H.Y.,Kim, S.,Kwon, C.J. 한국동물번식학회 1994 Reproductive & developmental biology Vol.17 No.4
This study was conducted to observe seasonal and individual changes in semen characteristics and sperm freezability, and sperm penetration into zona-free hamster eggs in Korean native goats. Buck response and change in semen characteristics to electrical stimulations was evaluated for four seasons throughout 2 years and percentage of motile sperm and normal apical ridge acrosome was investigated after equilibration and thawing for 4 seasons with 5 bucks. Sperm penetration rate was evaluated for 4 bucks. 1. Probe insertion at depth of 7cm and repeated stimulation for 3 sec was more effective(P<0.05) in buck response and semen collection than those of other conditions. 2. Semen characteristics from electrojaculation was signficantly(P<0.005) higher in spring and fall for semen volume, in spring and summer for sperm concentration and in fall for sperm motility than those in other seasons, respectively. However, there were no differences in total sperm among seasons. 3. Buck response to electrical stimulation showed significant difference(P<0.05) among individuals in all 3 seasons except winter. Significant individual difference in semen volume was only in spring and summer, but there was no indivudual difference in sperm concentration and total sperm in all season. 4. Washing of semen before freezing treatment was greatly(P<0.05) beneficial to sperm motility after thawing, no matter whether ejaculates exhibit egg yolk coagulation or not. 5. Sperm motility after glycerol equilibration was significantly(P<0.05) low in summer semen and motility after thawing was greatly(P<0.05) higher in winter semen than in other seasons. Freezability of unwashed sperm was significantly difference among bucks, but a yearly freezability of washed sperm after chilling and thawing were no differences among bucks and percentage of normal apical ridge acrosome were not different among seasons and bucks. 6. There was no significant difference in sperm motility after thawing between egg yolk levels in summer, although 20% level gave more higher motility than 5% level. 7. In summer, 3.2% glycerol and 3-h equilibration gave greatest percentage(P<0.05) of sperm motility and normal apical ridge acrosome after thawing. 8. Sperm penetration rate into zona-free hamster eggs was not different between bucks and seasons. Overall, it is concluded that to obtain maximum sperm output and successive semen freezing by electrojaculation method, buck selection with good response in all season could be basically considered and that seasonal effect on sperm freezability was more greater than that of individual bucks.
[가솔린엔진] 연소가시화를 통한 HD 천연가스엔진의 연소특성 연구
김영민(Y.M. Kim),이장희(J.H. Lee),이진호(J.H. Lee),신동성(D.S. Shin),정익재(I.J. Chung) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
At present study a IIL DI diesel engine was converted to a single-cylinder spark ignited CNG engine allowing optical access through an extended piston The fuel system also was converted to deliver CNG by injection into the intake ports and the cylinder head was modified to install a spark plug. The combustion characteristics of the engine were analysed by using direct imaging of the propagating flame with simultaneous measurement of in-cylinder pressure The effect of injection timing on the combustion in lean region is remarkable and intake-synchronous injection results in favorable combustion