• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.53-58
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• 2001

Fractal dimension is the method to measure the roughness and the irregularity of something that cannot be defined obviously by Euclidean dimension. And the analysis method of this dimension don't need perfect, accurate boundary and color like analysis lot diameter, perimeter, aspect or reflectivity of wear particles or surface. If we arranged the morphological characteristic of various wear particle by using the characteristic of fractal dimension, it might be very efficient to the diagnosis of driving condition. In order to describe morphology of various wear particle, the wear test was carried out under friction experimental conditions. And fractal descriptors was applied to boundary and surface of wear particle with image processing system. These descriptors to analyze shape and surface wear particle are boundary fractal dimension and surface fractal dimension.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.260-266
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• 2001

The surface temperature at the interface of bodies in a sliding contact is one of the most important factors influencing the behavior of machine components. So the calculation of the surface temperature at a sliding contact interface has long been an interesting and important subject for tribologist. Several methods for calculating surface temperature have been devised. Several numerical methods have been used to predict the temperature rise of sliding surface. but those need much time to calculate. In this study to reduce the calculation time the hybrid method using both semi-infinite solid analysis and FVM was used. It is founded that the computing time of hybrid method was shorter than that of FVM.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.273-280
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• 2003

The purpose of the paper is to investigate the noise characteristics of cylindrical roller bearings under radial load. The effects of radial clearance of the bearing, viscosity of the lubricant and number of the roller on the noise of the bearing are also examined. The results and discussions of the present paper might aid in the low-noise design of the cylindrical roller bearing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.768-770
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• 2014

A shaft of a reciprocating compressor receives bending force by piston, which makes movement of the shaft. The movement of the shaft affects durability and becomes a source of noise. In this paper, a cylinder is modeled by considering motion of a suction and discharge valve. The journal bearing is modeled by Bernoulli's equation. The trajectory of shaft which is considered cylinder and journal bearing can be calculated by finite element method. It will help a design of shaft to increase durability and reduce noise.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.35-46
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• 1990

The instantaneous friction in main bearings of a single cylinder diesel engine was determined by measuring the instantaneous angular velocity, calculating the resulting forces acting on the bearings, and solving the unsteady Reynolds equation in combination with the mobility method. The considered system consists of only the crankshaft with flywheel and oil pump. The thermal effects were not considered because of the short testing time. The tests were conducted using an electric start motor. The results indicated that when the bearing is not near equilibrium for very small speeds, simple film lubrication theories are not accurate. The details of grooves and unsteady terms in the Reynolds equation cannot be ignored for increasing efficiency of instantaneous friction calculation of the engine bearings. The effects of speed on instantaneous friction and energy lost in friction were determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.34-43
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• 2002

This paper focused on the dynamic behavior of camshaft in a direct acting type valve train system. To investigate camshaft behavior, transient vibration analysis is performed by using the transfer matrix method. The camshaft is treated as a lumped mass system supported by spring and damper, From the presented analytical model, we could predict dynamic behavior of camshaft, shaft locus within bearing and bearing load. The presented model and results will be very helpful to design the optimal camshaft and valve train system.

• The KSFM Journal of Fluid Machinery
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• v.9 no.1 s.34
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• pp.47-55
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• 2006

This paper presents the theoretical model to investigate the effect of Coulomb damping in the sub-structure of a foil bearing. Foil deflection is restricted by friction of bumps. Equivalent viscous damping of the bump foils is derived from the Coulomb friction. Dynamic equation of the bumps is constituted by stiffness and damping terms. This point give the difference from Heshmat's frictionless and simple compliance bump model. The fluid is modeled with the compressible Reynolds equation. A perturbation approach is used to determine the static and dynamic performance of the bearing from the coupled fluid-structural model. The analysis result shows that the static and dynamic performance is enhanced by bump friction. This analysis technique would be extended to development of a high performance bearing.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.392-400
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• 2001

The sealing performance of an elastomeric O-ring seal using bi-materials has been analyzed for the contact stress behaviors that develop between the O-ring seal and the surfaces with which it comes into contact. The leakage of an O-ring seal will occur when the pressure differential across the seal just exceeds the initial (or static) peak contact stress. The contact stress behaviors that develop in compressed O-rings, in common case of restrained geometry(grooved), are investigated using the finite element method. The analysis includes material hyperelasticity and axisymmetry. The computed FEM results show that the contact stress behaviors are related to a ratio of length between NBR and FFKM and temperature of vaccum chamber.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.135-140
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• 2001

In metal cutting at the tool-chip interface, friction generates considerable amount of heat. Thus, tile .knowledge of wear properties or the cutting tool material in high temperature has been known as one of tile important factors in need of clarification. The authors presented the wear properties of 5%V-5%Co-1%Nb high speed steel, fabricated by powder metallurgy, in room temperature in a previous article. The objective of this paper is to clarify tile effects of temperature ell its wear properties. Wear tests in sliding conditions under various temperatures have been conducted. The results indicate that tile wear properties of tile tool material in high temperature as well as in room temperature are excellent. It may be deduced that the oxide layer formed on the vol-n surface at high temperature is stable enough to prevent wear due to tile high temperature strength of its matrix.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1994.06b
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• pp.49-53
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• 1994

베인형 펌프, 모터 등의 마찰, 마모특성에 관해서 많은 연구가 있었으나, 베인펌프는 구조로부터의 제약이 많기 때문에, 대용량, 고압, 고속화라는 일련의 요구를 만족시키는 것이 쉽지 않아, 그 요구에 부응하기 위해 지금까지의 연구가 내마모성 작동유, 표면처리 기술, 특수 베인기구등의 개발을 제약에 부딪칠 때마다 필요에 따라 한결같이 경험적으로 이루어졌으며, 측정에 대한 면에서도 동적 조건 하에서의 측정은 거의 없으며, 해석에 관해서도 일반성이 상당히 결여된 상태라 할 수 있다. 따라서 본 연구에서는 유압 베인펌프의 베인과 캠링간의 접동 모델로써 동적 마찰 실험장치를 제작하여, 베인 선단의 마찰력을 측정하고 이를 기초로 하여 실기 유압 베인펌프의 베인과 켐링내면간의 접동부에 관한 마찰특성을 추정하는 것을 목적으로 하였다.