• Tribology and Lubricants
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• v.1 no.1
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• pp.30-37
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• 1985

동수압적 미끄럼베어링의 작동원리는, 두개의 서로 경사진 면이 윤활제를 그 사이에 두고 상대적인 운동을 함에 있어서 두면사이에는 윤활유 막이 형성되어 압력이 형성되고 두면에 작용하는 하중의 지지하게 되므로 직접적 마찰없이 상대적 미끄럼운동을 한다는 것이다. 동수압적 유체윤활은 윤활틈새 내의 윤활유동에 동수압적 점성유체역학 이론을 적용하며 베어링윤활유막의 압력분포를 계산하기 위한 편미분 방정식의 발견이 그 근본을 이루고 있고, 미끄럼베어링에 대한 기본적연구는 1900년 이래로 계속 수행되고 있다. 크랭크샤프트와 피스톤 연결봉 사이의 베어링은 동하중을 크게 받으며 회전하므로 저어널과 축의 상대운동은 회전운동과 윤활면의 수직운동으로 나누어 해석할 수 있다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.15-22
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• 2002

To carry out perfectly the forming analysis of the extruding products, it is necessary that the friction boundary condition between dies and blanks should be worked out the accuate numerical friction models. But the numerical friction models adapting in the conventional Extrusion forming software may be large different from the actual conditions. Expecially, the use of the existing extrusion forming software is possible only in the limitted range owing to the unaccuracy of the high speed forming work. Therefore, tile prepare of this study is to develop the numerical friction model which describes the friction boundary condition mathematically well, to improve the accuracy of the extrusion farming analysis, and finally to expand the applying areas of the results.

• Tribology and Lubricants
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• v.32 no.4
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• pp.107-112
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• 2016

This paper presents a rotordynamic analysis of the reduction gear system applied to the 250 kW super critical CO₂ cycle. The reduction gear system consists of an input shaft, intermediate shaft, and output shaft. Because of the high rotating speed of the input shaft, we install tilting pad bearings, rolloer bearings support the intermediate and output shafts. To predict the tilting pad bearing performance, we calculate the applied loads to the tilting pad bearings by considering the reaction forces from the gear. In the rotordynamic analysis, gear mesh stiffness results in a coupling effect between the lateral and torsional vibrations. The predicted Campbell diagram shows that there is not a critical speed lower than the rated speed of 30,000 rpm of the input shaft. The predicted modes on the critical speeds are the combined bending modes of the intermediate and output shaft, and the lateral vibrations dominate when compared to the torsional vibrations. The damped natural frequency does not strongly depend on the rotating speeds, owing to the relatively low rotating speed of the intermediate and output shaft and constant stiffness of the roller bearing. In addition, the logarithmic decrements of all the modes are positive; therefore all modes are stable.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1035-1042
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• 2014

Reducing the friction of engine parts is an important issue in engine design. The loss of energy in the piston assembly due to mechanical friction ranges from 40 to 55%, and there is an increase in the total energy of about 5% if the friction of the piston can be removed. In order to reduce the friction loss at the level of each engine part, it is necessary to perform a comparative analysis with other engines to determine the important factors affecting the energy loss. Several studies have been performed to analyze the lubrication based on hydrodynamic modeling, since a piston lubrication system has dimensions in the nanoscale to microscale domain. Therefore, it is necessary to determine the correlations between the molecular and continuum systems. In this study, we investigated the friction changes due to the various interactions between molecules in the wall/fluid interface, where a microscopic movement of the oil film occurs along the cylinder liner of the engine.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.430-435
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• 2008

This research deals with the implementation hydrodynamic (HD) lubrication system with an integration of multibodydynamics (MBD) in order to analyze bearing lubrication characteristics such as pressure distribution and oil film thickness dynamically. The HD solver developed newly will transmit force and torque data to MBD solver, and receive position and velocity data from it continuously. After an analysis, we will verify the result with existing commercial software. Moreover, other functions like adjusting size of mesh grid, setting oil hole & groove effects, and consideration of thrust force will be introduced.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.51-61
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• 1989

Recently, the growth in the propulsion power and propeller size of typical energy saving ships has resulted in severe damages of the oil-lubricated stern tube bearing. Consequently, a more rational analytical method for the design of the shafting system is required. In this paper an analytical method applicable to the design of the oil-lubricated stern tube bearing and shafting system is presented. The method consists of the finite element analysis of the shafting system and the oil film hydrodynamics. The shafting system is modeled as a three-dimensional problem using beam elements taking account for the steady components of thrust, lateral forces and moments of the propeller as well as the elastic foundation effects. The oil film hydrodynamics is modeled as a two-dimensional problem. Equal and retangular elements employing hourglass control method are used for the construction of the oil film fluidity matrix. To search the quasi-static equilibrium position between the propeller shaft and the oil film, an optimization technique is employed. Some numerical results based on the proposed method are compared with some measured and numerical data available. They show acceptable agreements with the data.