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[디젤엔진부문] 터보과급 디젤엔진에서의 급가속시의 압축 보조공기 공급에 의한 매연 저감
정인철(In-Cheol Jeong),김성초(Sung-Cho Kim),이경환(Kyung-Hwan Lee) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It has been one of the major disadvantages in the turbocharged diesel engine that the smoke level is increased during rapid acceleration due to the turbolag. In this research, it was tried to reduce the smoke with the system which can control the duration and timing of compressed auxiliary air at the front of the intake valves.<br/> The supply duration of the compressed auxiliary air was chosen as 20 or 30ms, and its pressure as 4,5,6,7 kg/cm2. The results showed that the desirable time and pressure were 20ms and 5-7kg/crn', respectively. The electronic circuit and photo sensor were adopted to control the duration and timing of air supply. It was also found that the smoke reached its peak value within 0.5 second after the rapid acceleration, and its normal condition was recovered after 1 second when the engine was operated at the unloaded or idling condition.<br/>
엔드밀 가공의 정밀도 향상을 위한 최적정삭여유에 관한 연구
최종근(Jong-Guen Choi),김형선(Hyung-Sun Kim),김성초(Sung-Cho Kim) 한국생산제조학회 2004 한국생산제조학회지 Vol.13 No.3
A significant error in the end milling processes is generated due to using slender tools of which the strengths are not sufficient. In order to obtain the desired machining accuracy, therefore, it is general that at first the rough cut is implemented, then the finish cut is followed. The rough cut eliminates large volume and the finish cut does the remained part. This remaining portion after the rough cut is called as the finish allowance. Larger finish allowances make it hard to get precise dimensions at a following finish cut. Smaller finish allowances are helpful for good dimension, but it sometimes is responsible for inferior surface qualities and over cuts. This study suggests a guidance for the optimum finish allowance for machining accuracy improvement, in which the rough cuts are regulated to remain the desired margins without any over cuts. Some experiments were carried out with various cutting conditions including the change of tool strengths and depth of cuts, and also extended to up millings as well as down millings.
유영현(Young Hyun Yoo),기현(Hyun Ki),최종욱(Jong Wook Choi),김성초(Sung Cho Kim),김용선(Yong Seon Kim),이용호(Yong Ho Lee) 大韓環境工學會 2009 대한환경공학회지 Vol.31 No.6
간이상수도 시스템에서 공급하는 식수는 일정한 잔류 약품(염소)량을 유지해야 하기 때문에 물과 약품의 혼합방법은 매우 중요하다. 본 연구에서는 물과 약품의 혼합방법을 최적화하기 위하여, 4가지 모델에 대한 농도분포 및 혼합지수를 구하였다. 그 중 2가지 모델에 대해서는 혼합효과가 높게 나타났다. 하나는 지하수 공급 파이프 중앙에 약품을 공급하는 모델이고, 또 다른 하나는 약품공급 파이프 하류에 반원형태의 블록을 설치한 모델이다. 이러한 모델들은 유동의 확산 및 교란을 야기시켜 혼합효과를 증가시키는 결과를 가져왔다. 이와 같은 수치해석 결과는 최적의 혼합효과를 얻기 위한 시스템을 설계하는데 도움이 될 것으로 기대된다. The mixing method of water and chemicals is significant in a small-scale water supply system because drinking water should be supplied with a certain quantity of remaining chemicals maintained. In the present study, the concentration distribution and the mixing index were obtained from four models, which were to find out the optimal mixing method of water and chemicals. The two models brought the good mixing effects out of the four, one for providing chemicals from the center of water supply pipe and the other for setting up the semicircle block at the downstream of the chemicals-providing pipe. As a result, the mixing effect was found out to be increased due to the diffusion and the disturbance of flows. In conclusion, these numerical results are expected to contribute to designing the optimal mixing system.