http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
크랭크축 경사도를 고려한 엔진 베어링의 유막거동에 관한 연구
김한구(Kim, Han-Goo) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.9
본 논문은 엔진 베어링에서 크랭크샤프트의 경사도를 고려했을 때와 고려하지 않았을 때 유막 동적거동을 컴퓨터 시뮬레이션을 이용하여 해석하였다. 본 해석은 탄성유체윤활 이론을 바탕으로 하여 최소유막의 동적특성을 수 치적으로 해석하였다. 유막설계에 매우 중요한 인자인 크랭크샤프트 경사도를 고려하기 위하여 크랭크샤프트와 엔진 베어링을 탄성체로 모델링 하였다. 유막거동해석을 위한 경계조건으로는 엔진 베어링에서 발생하는 비선형 구속력과 굽힘 모멘트를 고려하였고 이에 따른 크랭크샤프트의 경사도 영향을 고려함으로써 좀 더 실제 현상과 유사한 모델링 을 수행하였다. 해석결과 엔진 베어링의 성능에 가장 큰 영향을 미치는 최소유막두께가 크랭크샤프트의 경사도를 고 려하지 않았을 때보다 고려하였을 때 16%에서 24%정도 감소하는 것을 알 수 있었다. 또한, 해석결과에서와 같이 크 랭크샤프트 경사도 증가는 최소유막두께의 감소를 유발하고 이에 따른 베어링 파손을 예측할 수 있었다. 따라서 본 논문의 해석결과가 자동차 엔진 베어링 설계 시 매우 유용한 자료로 사용될 것으로 사료된다. The purpose of this paper is to analyze dynamic behaviors of the oil film thickness and engine bearings in both aligned and misaligned operation conditions of a crankshaft using computer simulation techniques. A crankshaft as an elastic body is modeled for a misaligned crankshaft which is very important design parameter of the film thickness and engine bearings. In this analysis, a dynamic characteristic of a minimum oil film is analyzed based on the elastohydrodynamic lubrication theory. The boundary conditions for analyzing the film behaviors include non-linear constraint forces and bending moments in engine bearings. The more expedient model of an engine bearing is extended to consider the effect of crankshaft misalignment. The computed results indicate that the minimum oil film thickness that causes a major influence on the performance of engine bearings has showed a decrease of 16% to 24% for the misaligned crankshaft compared with an aligned crankshaft. The computed results show that the misalignment of a crankshaft inevitably brings the reduction of minimum oil film thickness and this may increase the failure of a bearing. These results as design parameters are very useful for a bearing designer as a firm reference data of an automotive engine.
저가형 태양광 발전시스템을 위한 아날로그 MPPT 알고리즘의 특성 해석
김한구(Han-Goo Kim),이상용(Sang-Yong Lee),최문규(Moon-Gyu Choi),김홍성(Hong-Sung Kim),최규하(Gyu-Ha Choe) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
In this paper, Simple and inexpensive analog maximum power point tracker (MPPT) algorithm for photovoltaic power system and low power system of doesn't use digital signal processor (DSP). The control circuit is composed such that the actual current and voltage are sensed directly from the PV array. These two signals are then multiplied by a single-chip multiplier. The multiplier output go through different time constants genesis pulse width modulated to switch. Finally those were verified through simulation.
온도를 고려한 디젤유가 혼입된 엔진오일의 점도특성에 관한 실험적 연구
김한구(Han Goo Kim),김태환(Tae Hwan Kim),김청균(Chung Kyun Kim) 한국트라이볼로지학회 2006 한국트라이볼로지학회 학술대회 Vol.2006 No.6
An experimental study was conducted to evaluate the viscosity characteristics of multi-grade engine oils in which contains diesel fuels as functions of temperature variations. In this study, a diluted test sample for engine oils was made to have 5%, 10% and 15% fuel contents in unused engine oils, SAE 5W40, 10W40 and 15W40. The engine oil viscosity was measured with temperature variation ranging from -20℃ to 120℃ using a viscometer. The diesel fuel in which is blended to an engine oil plays an important role for decreasing an engine oil viscosity. Test results show that the viscosity tends to fall from a low temperature to a high one when a fuel mixed with engine oils. The viscosity variation in a low temperature zone is radically decrease compared with a high temperature zone. An equation that can predict the viscosity with the fuel dilution, based on the empirical result was expressed in the exponential function with the variation of the temperature was shown. The 5W40 engine oil showing low viscosity characteristic in the low temperature region matches close with the theoretical equation and the experimental result. The 15W40 engine oil showing high viscosity characteristic in the low temperature region however shows little difference with the theoretical equation and the experimental result. With the theoretical equation, it is possible to predict the limitation of the fuel dilution which doesn't affect as the influence of the engine elements at the concept design stage of the CDPF development system.
김한구(Han Goo Kim),김청균(Chung Kyun Kim) 한국트라이볼로지학회 2009 한국윤활학회지(윤활학회지) Vol.25 No.1
In this paper, the minimum oil film thickness and the maximum oil film pressure of engine bearings have been analyzed by using the elastohydrodynamic theory and Taguchi's design method as functions of the oil groove width, oil hole diameter, oil hole position, and oil supply pressure. The optimized design of the engine bearing for an automotive Diesel engine is very important for supporting a load-carrying capacity due to gas pressures from the engine combustion chamber and inertia forces of the piston. The optimized design data of engine bearings indicated that the optimized oil groove width and an oil diameter of a engine bearing are 8㎜ at the speed of2,000 rpm for a given 4-cylinder Diesel engine. Thus, the oil groove oil groove and an oil hole for high performances of an engine bearing may be considered as major design parameters compared to other design factors, which are strongly related to the minimum oil film thickness and the maximum oil pressure distribution of the engine oil.
엔진오일의 저점도화가 차량 연비에 미치는 영향에 관한 실험적 연구
김한구(Han Goo Kim),김청균(Chung Kyun Kim),현영준(Young June Hyun) 한국트라이볼로지학회 2006 한국트라이볼로지학회 학술대회 Vol.2006 No.11
The purpose of this paper is studying fuel economy improvement experimentally, when viscosity of engine oil is lowered. The emissions are measured for CVS-75 mode with SAE viscosity grades. The test results indicate that a close correlation has been found between the engine oil viscosity and the fuel economy. The lowering of engine oil viscosity causes the reduction of friction loss which has a very close relation with the fuel economy. These results as the lowering of engine oil viscosity will be a important factor for improvement of the fuel economy and reduction of the CO₂ emission.