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한동철(D.C.Han),조명래(M.R.Cho),정진영(J.Y.Jung) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
This paper presents thermo-hydrodynamic behavior of circular journal bearing under the static loads. Oil film pressure is obtained by solving the Reynolds equation considering viscosity variation according to the circumferential temperature variations in the fluid film. Temperature of oil film is obtained by solving the Energy equation and heat transfer equation. Effects of oil recirculation and cavitaion are considered. Results show that the THD analysis is required to predict more accurate maximum temperature of the journal bearings driven in high speed and high load condition.<br/>
김충(C. Kim),김주호(J.H. Kim),천길정(G.J. Cheon),정태형(T.H. Jeong),한동철(D.C. Han) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_1
Dynamic behavior of planetary gear train for automatic transmission is investigated. Gear meshes are modelled as springs and dampers varying with time. Rolling bearings supporting planet gears are modelled as radial springs. Carrier center locus and dynamic forces acting on gear meshes and supporting bearings are calculated after numerical integration of governing equations. Dynamic behavior is very different from what we know from static analysis. The results show that carrier center locus and shape of forces become simple as rotating speed is increased and that force acting on sun/planet gear mesh is different from force acting on planer/ring gear mesh. Finally, maximun gear mesh load graph can be made out of above result.<br/>
기어의 강성변화를 고려한 유성기어열의 동특성 해석 연구
김충(C. Kim),김주호(J.H. Kim),이정한(J.H. Lee),조영일(Y.I. Cho),천길정(G.J. Cheon),정태형(T.H. Jeong),한동철(D.C. Han) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_1
Dynamic characteristics of planetary gear train (PGT) of vehicle transmission is investigated. Engine torque is transfered by transmission, which is composed of torque converter, cutches and several PGTs. The load from torque converter fluctuate irregularly, so the dynamic force on gear tooth varies nonlinearly. For dynamic analysis, stiffness of gear teeth is calculated according to variation of contact ratio. Static and dynamic model for one stage PGT are suggested, and analyzed by 4th Runge- Kutta method. The results show that the locus of sun gear and dynamic force decrease and the frequency effect of external load is decrease as rotational speed increases.<br/>
나병철,안영재,한동철,전경진,Na, B.C.,An, Y.J.,Han, D.C.,Chun, K.J. 대한설비공학회 1994 설비공학 논문집 Vol.6 No.4
One of the chlorofluorocarbon compounds. R-12 deplete atmospheric ozone. It leads to international agreement to reduce CFC production. R-134a has similar thermodynamic properties to CFC-12. It has zero ODP(Ozone Depletion Potential). This Paper focuses on the lubricating oils for using with R-134a PAGs(Polyalkylene Glycol's) and esters are primary lubricants that are now being tested for use with R-134a Because of extreme polarity of R-134a. there are many problems in the selection of lubricating oil. This investigation analyzes compressor working conditions and calculates wear parts friction for simulation testing. Miscibility and material compatibility is proved by sealed glass tests. Friction was tested on the closed type pin on disk wear tester. This equipment simulates actual refrigerating compressor. Environment controlled test made more reliable result than field test Conventional oils(mineral oils, Alkylbenzene, PAO(Polyalpha Olefin) are immiscible with R-134a. PAGs and ester oils are miscible with R-134a. Friction coefficient is similar to conventional system(mineral oil/R-12 systems) at operating condition. At start & stop condition, PAGs/R-134a system has high friction coefficient. It provide reliable result on the lubricity, miscibility, material compatibility of R-134a with these new lubricants. It suggests proper selection of refrigeration oil that may improve compressor durability of performance.
천길정,이정한,한동철,Cheon, G.J,Lee, J.H,Han, D.C 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.5
Decision process for length dimension in the mechanical system design process has been studied with a washing machine transmission as a model. The results are, (i) the length dimensions of the non-shaft elements are independent of other elements, (ii) the length dimensions of the shaft elements are dependent on the dimensions of the non-shaft elements located inside and outside of that elements, (iii) the length dimensions of the inner shaft elements are dependent on those of the outer shaft elements located parallel, (iv) the length dimensions of the shaft elements located serial are independent of each other.
HLA를 장착한 직접 구동형 OHC 밸브 트레인 시스템의 마찰 특성 해석
지유철(Y. C. Ji),조명래(M. R. Cho),한동철(D. C. Han),최재권(J. K. Choi) 한국자동차공학회 1998 한국 자동차공학회논문집 Vol.6 No.3
A dynamic model of direct-acting OHC valve train system has been used to determine the load conditions in the system. The modified equations for calculating the friction forces between cam and HLA, and at a camshaft bearing have been defined considering the lubrication conditions. Then, to understand the frictional characteristics in the system, a parameter study has been performed. As the results of the analysis, valve spring stiffness and preload have great effects on the friction in the system, but the effects of other parameters are negligible. So, how to design the valve train system with respect to the reduction of friction is to minimize the valve spring stiffness and preload in the limit of satisfying the dynamic constraints.<br/>
EHPS용 압력 평형형 베인 펌프의 압축 과정에 관한 연구
조명래(M. R. Cho),한동철(D. C. Han),장주섭(J. S. Jang),박민호(M. H. Park),이충호(C. H. Lee) 한국자동차공학회 1996 한국 자동차공학회논문집 Vol.4 No.5
This paper reports on theoretical study of the compression process within balanced type vane pump for Electro-Hydraulic Power Steering(EHPS). Equations of camring profiles are derived, then displacements, velocities, accelerations, and jerks are calculated. Vane side leakages, vane slit leakages, and rotor side leakages are considered and calculated. Numerical integration of flow equation is performed using 4th Runge-Kutta method. As a result of analysis, it is found that chamber pressure depends on rotational speeds, bulk modulus of fluid, notches, camring profiles, and positions of delivery port. Especially, the variation of notch area is the most important factor that prevents pressure from rapid rising.<br/>