• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.96-101
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• 2001

This paper shows the temperature characteristics of a high speed angular contact ball gearing which is 7004C type with ISO P2 tolerance class. A built-in motor type high speed spindle which adopts an oil-air lubrication system was used to measure the temperature rise up to 60,000rpm. The gearing temperature was measured using thermocouples that were attached to the outside surfaces of the outer rings. The result showed that the continuous test method which was suggested in this paper is more effective than on and off method and the lubrication oil supply rate should be reduced in high speed rolling bearings as long as the seizure does not occur. And the result were confirmed that the bearings packed with ceramic balls are superior to those with steel balls in temperature characteristics.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.9_10
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• pp.1093-1100
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• 2003

Following a treatment with edible oils and/or washing, the tensile properties of vulcanized rubber were measured to assess the effect of the sorbed edible oil. Rubber soiled with soybean oil, after 8 weeks storage in a 30$^{\circ}C$ incubator, retained 61% of its original strength, and rubber soiled and washed retained the 73%. The strength of the rubber soiled with oil decreased remarkably during the first 2 weeks. After repeating this soiling and/or washing 7 times, the soiled rubber had only 16％ of its original strength, the rubber soiled and washed had 45%. In all cases, breaking elongations were not decreased as much as tensile strengths; therefore , more of the elasticity of the rubber remained than did the strength. From these results it is concluded that washing after soiling with oils is very helpful in maintaining the strength of rubber. In this study, three different surfactant solutions, AS, AE and AS/AE, were used. In the AS solution, the contact angle of the soybean oil was greater and the work of the detergency was the smaller than in either the AE or the AS/AE solution, the loss of the strength of the rubber washed in AS solution did not decrease significantly. These results suggest that rolling-up, emulsification and solubilization also participate in the removal of oil from rubber.

• Journal of the Korean Applied Science and Technology
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• v.23 no.3
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• pp.192-198
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• 2006

To provide an aqueous rust inhibitor for metalworking lubricant having low toxicity and excellent rust resistance, we synthesized diester of malonic acid by three consecutive esterifications with over 98% of conversion. This substituted malonic diester could be used as an additive to mineral oil based metalworking lubricant. These metalworking lubricant compositions were showed excellent rust resistance and suitable for various metals and different metalworking processes including hot rolling and cold rolling of aluminum and aluminum alloys.

• Tribology and Lubricants
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• v.7 no.1
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• pp.55-60
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• 1991

The emulsion lubrication is expected to get the effects of cooling and lubrication in metal cutting. The purpose of this research was to investigate the lubrication characteristics of the emulsion in a region of the elastohydrodynamic lubrication by experiments using o/w type emulsion lubrication. With the line contact frictional experiment apparatus which is the model of a rolling mechanism, friction coefficient, and oil film thickness were measured. By analyzing these experimental data with the variables of emulsion concentration, load, and rolling velocity, the following results are obtained. Emulsion viscosity $\eta$ for the concentration and pressure can be calculated by the following equation $\eta=\eta_o e^{\alphap}\cdot e^{\beta \phi}$. Where $\beta = (-3.7242+\phi)/\phi, 5%\leq \phi \leq 15%$.

• Tribology and Lubricants
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• v.27 no.6
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• pp.321-325
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• 2011

Nanodiamond was dispersed in paraffin liquid oil to investigate the effects of nanodiamond at the marginally lubricated condition. Scuffing test and immediate loading sliding wear test were conducted using the fabricated nanodiamond oil. As a result, dispersion of nanodiamond in oil leads to increase in scuffing life, and nanodiamond contents affects the scuffing life. In case of immediate loading sliding wear test, the result was different according to hardness of specimen. If hardness of specimen was low, abrasion of nanodiamond occurred actively. If hardness of specimen was increased, however, nanodiamond can act as a spacer or rolling between contacting surfaces.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.90-97
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• 2018

As the result(also after it's been carried out the damping force test with 800ea lateral dampers of 50ea trainset from entering heavy maintenance workshop to implement heavy maintenance inspection cycle, there were 86.25%(650ea) which were out of $350kg{\pm}15%$ of the standard value of damping force compared to the reference value. After the implementation of heavy maintenance inspection cycle, it's been examined damping force test with total samples 32ea(samples 8ea per a trainset) from actual running EMU 4ea trainset. As the result, percent defective was 84.4%(27ea), which was a very high level. System. The lateral damper's the failure cause of damping force defective was oil leakage caused by tearing crack of oil seal and foreign material in oil iron 473 ~ 1932 times higher than that of new oil, copper 36 ~ 98 times higher than that of new oil reduced oil amount cycling damping valve. It resulted from the change cause of damping force. In the static analysis on the shape of lateral damper oil seal's the existing and improved product, the stress of the improved product was smaller than that of the existing product. In the fatigue analysis, the existing product showed a low life in the upper area. However, in case of the improved product, it could be confirmed that the destruction did not occur up to the specified 1.0e + 006 cycles and the lifetime was further improved in most areas.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.859-867
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• 1998

An oil lubricated Herringbone aroove jounal bearing(HGJB) with eight-circular-profile grooves on the non-rotating bearing surface is analyzed numerically and experimentally. The load carrying capacity, attitude angle, stiffness and damping coefficients are obtained numerically for the various bearing configurations. The onset speed of instability is also examined for the various eccentricity ratios. The configuration parameters of HGJB, such as groove depth ratio, groove width ratio, and groove angle, are dependent on each other because the grooves are generated by using eight small balls rolling over the inner surface of the sleeve with press fit. Therefore, it is not allowed to suggest a set of optimal design parameters such as the one for the rectangular profile HGJB. The overall results from numerical and experimental analysis prove that the circular profile HGJB has an excellent stability characteristics and the higher load carrying capacity than the plain journal bearing.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.105-110
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• 2002

The use of microporous polymer lubricants (MPLs) can eliminate the storage, sealing, and pumping problems associated with liquid lubricants, This paper discusses the use of MPLs for a component as rolling-element bearings. An MPL composed of 40% HDPE and 60% ester oil was synthesized and the MPL was applied to a ball bearing. The MPL ball bearing, filled with the MPL instead of the usual grease pack, tested and compared with the usual grease sealed ball bearing. The MPL applied to a ball bearing showed lubricant properties as good as usual grease, and showed higher performance in bearing oil leakage test, rotating torque test and thermal test at high speed running than usual grease.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.19-24
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• 1997

The operating torque and tribological characteristics of the cam/tappet system in an I.C. engine have an important effect on engine efficiency. In this paper, we measured the torque of cam/tappet system with respect to the oil temperature and camshaft speed to characterize the tribological behavior. Also, accelerated test was performed to analyze the wear characteristics of cam/tappet interface. The torque of the cam/tappet system decreased with respect to camshaft speed and was not significantly affected by the oil temperature. The results of accelerated test showed that the running-in wear occurred during the tests and the center of the tappet was mainly damaged by the rolling and sliding friction.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.364-373
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• 2001

This paper describes the variation of lubricant's temperature effects on elastohydrodynamic lubrication. The Newton-Raphson technique was used to solve the simultaneous system of Reynolds and elasticity equations. To show effects of lubricant's temperature, average temperature across the oil film was calculated using the energy equation. Pressure distribution, film shape, and temperature distribution were obtained for fully flooded conjunctions, and various dimensionless speed parameters while load and material parameters were held constant. Minimum film thickness were obtained for various material properties while load and velocity were held constant. It is drawn that the thermal effects have a strong influence on a minimum film thickness under high rolling velocity and slip ratio.