• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.10a
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• pp.181-187
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• 1995

The effet of glass fiber and graphite on the wear properies in tin-bronze alloy matrix composites was studied by a pin-on-disk type wear testing machine. The results obtained from the wear test were analized by SEM observations of worn surfaces of pins and disks and EPMA composition measurments. The amount of wear was devreased as increasing the content of glass fiber in matrix, since the alloy matrix was reinforced by glass fibers. The wear mechanism of the matrix specimen without glass fibers was proved as the contact area delamination. Oxide layer formed on sliding surface led to the increasing wear resistance. Specimens containing graphite particles showed an lubrication effect to counter disks.

• Carbon letters
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• v.10 no.2
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• pp.94-96
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• 2009

[ $C_f/C-Cu$ ]composites were fabricated by infiltrating molten Cu into different $C_f/C$ preforms prepared by chemical vapor infiltration, resin impregnation and carbonization. The microstructure and properties of the composites were investigated. The results show that Cu in the composites filled the pores and showed network-like distribution. Compared with homemade J204 brush material and certain grade pantograph slider from abroad, the composites have higher flexural strength and better electrical conductivity. The friction and wear properties of the composites are better than that of J204, and closed to that of the abroad material.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1513-1518
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• 1992

Numerical solution technique is suggested to analyze the vibration of a spring composed of stacked beams fastened together. Bernoulli-Euler beam theory for small deflection is used, and incremental Coulomb friction law is adopted for the interface friction. The validity of the present solution technique is checked for the perfectly bonded case and the perfect sliding case.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1608-1613
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• 2003

In the semiconductor and the optical industry, a new transport system which can replace the conventional sliding system is required. These systems are driven by the magnetic field and the conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problems. In this paper, the object transport system using the excitation of ultrasonic wave is proposed. The experiments for finding the optimal excitation frequency, finding phasedifference between two ultrasonic wave generators are performed. The relationship of transporting speed according to the change of flexural beam shape is verified. In addition, the system performance for practical use is evaluated.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.13-18
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• 2004

In precision mechanical components that experience sliding, it is important to reduce the friction to minimize surface damage. Particularly, new lubrication methods are needed to reduce friction in silicon based micro-systems applications. In this work, the tribological characteristics of PFPE (Perfluoropolyether) Zdol lubricant on silicon were investigated based on the thickness of the film. The lubricant was coated on silicon wafer specimens by the dip coating method. It was shown that the friction coefficient as well as stiction decreased as the thickness of the film increased. The results of this work may be applied to improve the tribological performance of silicon based micro-system components.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.165-166
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• 2006

Surface pattern of tribological applications is an attractive technology of engineered surface. Therefore, friction reduction is considered to be necessary for improved efficiency of machines. This study investigated the effect of friction property fur angles of micro-scale crosshatch grooved surface pattern on bearing steel flat mated with pin-on-disk. We obtain sample which can be fabricated by photolithography process. We discuss friction property depend on an angle of cross-hatch grooved pattern. We can verify the lubrication mechanism as a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter under the lubrication condition. It was found that the friction coefficient was related to angle of crosshatch on surface, even when surface pattern was the same density.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.696-699
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• 2003

In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. There systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the object transport system using the excitation of ultrasonic wave is proposed. The experiments for finding the optimal excitation frequency, finding phase-difference between two ultrasonic wave generators are performed. The relationship of transporting speed according to the change of flexural beam shape is verified and the system performance for practical use is evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.924-929
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• 2008

The rate of wear of cam followers in a valve train system is mainly a function of contact stress between the cam and the follower, sliding velocity and hydrodynamic film thickness between the two mating surfaces. The wear or surface fatigue can be reduced by maximizing the elastohydrodynamic film thickness. In this paper, an attempt has been made to estimate the optimal specific film thickness of cam-follower system quantitatively. A general TES polynomial function with real values of exponents is developed and genetic algorithm (GA) is used as optimization techniques for maximizing the minimum specific film thickness. The optimization programs enumerate values of the exponents for synthesis of cam displacement curves. The results show that the minimum film thickness can be increased considerably, e.g. approximately 7% in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.841-844
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• 2003

In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. These systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the vibration behavior of flexural beam in the ultrasonic transport system is verified using Laser Scanning Vibrometer. The experiments for verifying vibration are performed in three conditions such as in the maximum transport speed, in the zero speed, and in the change of transport direction.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.105-111
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• 2003

The valve train system of engines has long been a sensitive area with respect to wear performance because of the high contact loads and surface sliding speeds encountered. In particular, wear problems of load-carrying components in relative motion, such as cam and tappet in valve train system have made troubles. To overcome these problems, combination of proper materials is important, as well as selecting of high wear performance materials. This paper presents the experimental result of friction and wear properties of ca/tappet materials. To investigate friction and wear properties for several combinations of materials, using commonplace tribometer(Plint 77, reciprocating type), we make a selection of a optimum material combination.