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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/>
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.
용기와 관으로 구성된 수처리 장치에서 압력 수두 및 유량 변화와 자유 진동 현상
김성초,김기성 순천대학교 공업기술연구소 1996 工業技術硏究所論文集 Vol.10 No.-
This paper describes the pressure head - flow rate variation and free vibration phenomena in the tank - pipe systems which is a simple model of the water treatment. The system consists of the storage tank and serial connection pipes with the different diameters and lengths. When the flow is controlled by the valve attached at the end of pipe, the pressure at this end is excessively large and shows small oscillation comparing that of tank, and the flow rate decreases to zero monotonically as time goes by. In the primary mode shape obtained by the free vibration analysis, the amplitude of pressure is 6 - 7 times of the tank pressure, and that of flow rate is about 12% of the normal state. Especially the phase of pressure is more delayed by ½π radian than that of flow rate.
김성초 順天大學校 1995 論文集 Vol.14 No.1
This paper describes the vortex ring element method, which is applied to calculate the unsteady aerodynamic forces on the delta wings. The computational results agree well with the experiments in the moderate range of angle of attack in spite of small number of panels. And the discrepancy between them in the high angle of attack is partially due to the zero thickness of wing in this research and to the poor prediction of roll-up vortices formed in the leading edges. The aerodynamic forces are very large when flow starts, however, they reach steady-state values respectively before long. The ground effect on aerodynamic coefficients becomes more favorable as the angle of attack increases.
김기성,김성초 順天大學校 1997 論文集 Vol.16 No.1
This technical paper describes the aerator design procedures. A hypolimnetic aeration system is used to improve the raw water quality by supplying the air by force into the sublayer of the water source, so the forced circulation is induced, and the desolved oxygen is increased and it prevents effectively the temperature weak layer in the lake from forming. Namely, it is adopted to reduce the eutophication and prevent the unpleasant taste and odor. The design procedure for a hypolimnetic aerator, generally used to purify the water source. is set up through this development research. Thus the dimension and number of the aerator, and the type and power of the air compressor can be determined. In addition, a model of about 5:1 scale is designed and made, and it can be adapted and modified to apply practically in the construction work based on the above mentioned design procedure, and especially it may be necessary to consider the variable length aerator for coping with the depth of water.
단순화된 표시자-세포 방법으로 해석한 물방울이 자유 표면에 떨어질 때의 현상
김성초 順天大學校 1991 論文集 Vol.10 No.1
본 논문은 단순화된 표시자-세포 방법을 사용하여 한 방울의 액체가 그릇에 담긴 액체의 자유표면 중앙으로부터 약간 왼쪽에 떨어질 때의 현상을 해석하여 타당한 결과를 얻었다. 유동의 일반적인 현상(numerical visualization)과 유선, 와도 및 압력 분포를 구하였으며 압력 분포를 제외하고는 대략적으로 대칭적인 분포를 한다고 볼 수 있다. 특히 액체 방울이 그릇의 중앙으로부터 왼쪽으로 편향하여 떨어졌기 때문에 유선 등에서는 오른쪽 영역에서 흥미로운 현상들이 발견되었는데 이것이 관연 물리적으로 타당한지, 아니면 수치적 오차나 수치 계획의 오류에서 비롯한 것인지는 앞으로 규명해야 할 문제로 생각된다. 또한 액체 방울이 컵과 같이 축대칭인 자유 표면에 떨어지거나 호수처럼 무한 크기의 자유 표면에 떨어질 때의 현상과 낙하 속도의 영향, 액체 방울 크기의 영향 등도 해석해 볼 필요가 있을 것이다. This paper describes two-dimensional flow phenomna when a single droplet drops on the free surface of the fluid contained in the vessel. The marker and cell(MAC) method can successfully solve the free surface problems such as the surface wave, two droplets collision and the dropping droplet on the fluid contained vessel. The MAC method is somewhat inefficient since it solves all the primitive variavles, velocities and pressure, however the simplified marker and cell (SMAC) method, which is adopted in this study, is easy to use and its computation time is also short because it avoids solving the pressure terms directly. Both the MAC and SMAC method are characterized to be applied to the cells which constitute of thecalculation domain, and in which the massless particles exist. Since a droplet drops on the slightly left-hand side of the vessel center in this study, the flow patterns-streamlines, vorticities and pressure dustributions-of course loose a little the symmetricity. But they are similar one another after a droplet jumps into the fluid. Especialy it is interesting that many small vorticies are found in right part of the streamlines, and that the fluid surfaces well accord with the zero pressure lines at the same time level.