• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.323-329
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• 1998

The effect of humidity on friction characteristics of friction materials were studied using a pad-on-disk type friction tester. Three different friction materials containing simplified ingredients were investigated by changing the solid lubricant, graphite, MoS$_2$, and $Sb_2S_3$. A friction material without solid lubricant was also examined to study the effect of ingredients in the matrix on humidity. Friction material containing graphite showed lower friction coefficient at high humidity level than other conditions, however, friction material containing MoS$_2$ indicated higher friction coefficient at initial stage under high humidity level. Friction materials without solid lubricant and with $Sb_2S_3$ were little affected by humidity conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2159-2164
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• 2002

This paper reports on the effects of additional factors on the engine friction characteristics. The total friction loss of engine is composed of pumping and mechanical friction loss. The pumping loss was calculated from the cylinder pressure, and the mechanical friction loss was measured by strip-down method under the motoring condition. The various parameters were tested. The engine friction loss was much affected by oil and coolant temperature. The low viscosity oil was very effective to reduce the friction loss, and friction modifier was very useful to reduce the friction loss at lower engine speed. The engine friction loss was varied with engine running time because of surface roughness decreasing and oil degradation. To prevent oil-churning effect, it was very important to maintain the proper oil level. The presented results will be very useful to understand friction characteristics of engine.

• Tribology and Lubricants
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• v.19 no.6
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• pp.365-369
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• 2003

This paper presents an experiment of the characteristics of lubricating oils for refrigerating and air conditioning. We investgate influences of lubricating oils and additives on friction and wear by reciprocating type and pendulum type friction testers. The result shows that polyolesters have excellent friction characteristics and poor effect of additives. In contrast, polyvinylethers gave higher coefficient of friction, low wear amount and good effect of additives. We can see good relationship between the coefficients of friction in recipricating type and pendulum type friction testers.

• KSTLE International Journal
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• v.4 no.1
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• pp.27-30
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• 2003

The basic principles of tribo-systems and study method based on tribe-systems are introduced in the paper, Based on the viewpoint of tribe-systems, the experiment on tribology characteristics of friction lining material in multi-rope friction hoist is carried out. The research result shows: tribology characteristics of friction material are not its inherent characteristic but system characteristics of the tribo-systems, the“sliding-rope”of multi-rope friction hoist can be divided into“safety sliding-rope”and“fault sliding-rope”, study on friction material only based on characteristic of system where friction material exists possesses practical significance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.219-224
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• 1999

The effects of solid lubricants on wear and friction characteristics of friction materials were studied using a pad-on-disk type friction tester. Friction materials with ten formulations containing different relative amounts of solid lubricants(graphite, MoS$_2$and Sb$_2$S$_3$) were investigated. Results of this work showed that each formulation with different relative amounts of the lubricants had unique friction characteristics. At low brake temperatures, friction materials containing rich graphite showed a small amount of $\mu$ change during sliding. At elevated temperatures, on the other hand, friction materials with rich Sb$_2$S$_3$and graphite showed smaller $\mu$ changes suggesting complementary lubrication of Sb$_2$S$_3$and graphite during sliding. However, the friction materials with rich Sb$_2$S$_3$showed a large amount of wear.

• Tribology and Lubricants
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• v.18 no.5
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• pp.339-344
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• 2002

Whenever moving surfaces of machine driving elements interact in air and lubricating oil, oxidization film on the surfaces are generated. It is effect to prevent friction and wear on contact area. Since the electronic current progress the oxidization of metal, if the electronic flow be regulated, the thickness of oxidization film can be regulated and friction characteristics can be improved. But the electronic current can deteriorate friction characteristics, so various characteristics must be investigated on transforming of electronic current. Therefor, using the Norton equation in this study, short current were transformed between frictional materials using ball on disk type tester. It was studied on effect of electronic current for friction characteristics.

• International Journal of Automotive Technology
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• v.3 no.4
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• pp.171-176
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• 2002

A bench test set-up is employed to simulate the friction characteristics of a paper-based friction material operating against a steel plate. Dry friction tests are run as well as tests with transmission fluids. Glazed friction material produces a negative coefficient of friction versus sliding velocity (f-v) curve for both dry friction and lubrication with transmission fluids. At low sliding speeds, the coefficient of friction when operating in transmission fluids for glazed friction materials is greater than that under dry friction. An appreciable negative f-v slope occurs at low sliding speeds for glazed friction materials when running with the transmission fluid. The friction material after running in produces a constant f-v curve under dry friction and a negative slope when lubricated with transmission fluid. At low sliding speeds, the coefficient of friction of the run-in friction material is lower than that of the glazed wet material. On the other hand, the run-in friction material has a larger friction coefficient than does the glazed friction material at higher sliding speeds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1417-1426
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• 2009

Various types of damper are usually applied to reduce noise and vibration for mechanical systems. Especially, for washing machines, the free-friction stroke damper is installed. The behavior of the free-friction stroke damper has nonlinear characteristics such as hysteresis and viscoelastic properties because of its foam material. First of all, the dynamic experiments were carried out by using a MTS machine to find characteristics of the free-friction stroke damper. And the simulation model of the free-friction stroke damper and characteristics of a foam material were evaluated by using optimization technique. To make a good simulation model which can show the dynamic characteristics, it is important to understand the working mechanism of the damper. The Finite Element Method (FEM) technique can help us instinctively understand the damping phenomenon under operating conditions, because we can observe the condition of damper at every step in the simulation by using it. Also, by changing factors, we can comprehend the variation of characteristics of damper. So, in this paper, a study on the dynamic characteristics of free-friction stroke damper by FEM is focused on. Finally, the possibility which physical experiments can be replaced into simulations is shown.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.16-21
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• 2002

Generally, Oxidization film are generated by friction and wear in lubricant oil. It is effect that the heat and pressure act on contact area. Because the electrons movement progress the oxidization, if the electrons movement be regulated, the thickness of oxidization film can be regulated and friction characteristics can be improved. But electronic current can deteriorate friction characteristics, so various characteristics must be investigated on transforming of electronic current. Therefor, using the Norton equation, short current were transformed between ball and disk. Also, an experiment was carried out using ball on disk type tester. So, we studied up on effect of current for friction characteristics.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.150-155
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• 2002

Generally, Oxidization film are generated by friction and wear in lubricant oil. It is effect that the heat and pressure act on contact area. Because the electrons movement progress the oxidization, if the electrons movement be regulated, the thickness of oxidization film can be regulated and friction characteristics can be improved. But electronic current can deteriorate friction characteristics, so various characteristics must be investigated on transforming of electronic current. Therefor, using the Norton equation, short current were transformed between ball and disk. Also, an experiment was carried out using ball on disk type tester. So, we studied up on effect of current for friction characteristics.