• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.296-300
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• 2004

Currently. the study on structural ceramic helps to suggest the precise data of friction and wear in accordance with the various conditions in operations. Also, the study helps to predict effective operating conditions by monitoring the occurrence of wear transition. The studies in the Past were mainly concentrated in using identical materials. However, it is highly likely to have unqualified data from the differences of mechanical and chemical properties between ceramic materials. Thus, in this study, through conducting the ball-on-disk type wear testing, the different ceramic materials has been used to consider tribological characteristics between different ceramic materials. We conducted the wear test by using three kinds of specimen which are zirconia, alumina and silicon carbide against zirconia. We have changed the sliding velocity and the loading conditions in this test and found out that there is row friction coefficient and wear rate in the combination of zirconia and silicon carbide.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.851-856
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• 2002

Tribological behavior of plasma-sprayed $Cr_2O_3$-based coatings containing $MoO_3$ at 450$^{\circ}C$ was investigated to understand the influence of $MoO_3$. A reciprocal disc-on-plate type tribo-tester was employed to examine fricition and wear behavior of the specimens. The microstructure and phase composition of the coating was characterized with Transmission Electron Microscopy(TEM). The TEM analysis indicated that $MoO_3$ was dispersed into the grain boundary, resulting in the increase of the hardness and density of the coating. Worn surfaces were investigated by scanning electron microscopy and chemistry of the worn surfaces was analyzed using a X-ray Photoelectron Spectrometer(XPS). The results showed that the friction coefficient of the $MoO_3$-added coatings was lower than that without $MoO_3$ addition. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with $MoO_3$ composition in the protecting layer appears to be more favorable in reducing the friction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.110-114
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• 2008

In this study, to examine the friction coefficient and wear amount of dental prosthesis, pin-on-disk type wear test were at room temperature. Vickers hardness and fracture toughness measurement of dental materials were preformed. Microscopic observations on worn surfaces of specimens were conducted by SEM. The friction coefficient of dental material was investigated according to weight and slinging velocity. dental material have investigated composed to nature teeth.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.60-60
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• 2004

광디스크 미디어 저장기기에 있어서 음악과 영상을 재생하는 광디스크 플레이어의 기구부품 중 턴테이블은 디스크를 장착, 고정하여 디스크에 기록된 신호를 재생케 하는 광디스크 메커니즘의 중요기능 부품이다. 특히 별도의 클램퍼 없이 턴테이블에 부설된 탄지력만으로 디스크를 장착, 고정하는 슬림형 플레이어에서 스핀들 모터의 회전 시 턴테이블에 장학된 광디스크의 슬립은 재생에러를 야기한다. 스피닝 회전속도가 증가할수록 디스크의 슬립을 방지하기 위해서는 디스크와 턴테이블의 증가된 마찰력이 요구된다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.127-133
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• 2003

Pin-on-disk and hardness tests using mechanical components of M-20J aircraft braking system were performed to identify the friction and wear characteristics. The intention of this work was also to analyze a 5-year term maintenance record of an M-20J aircraft. used for flight training at Hankook Aviation University, and to determine the reliability of the brake system of an M-20J aircraft. The mean wear coefficients of the lining sliding against the brake disk were compared between the test and reliability estimation to obtain a predictive wear model.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.48-48
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• 2000

진공부품에 사용되고 있는 재료는 여러 가지 있으나 회주철품은 진동 감쇄 및 흡진성이 우수하여 소음 발생이 적고, 조직 중에 흑연이 존재하므로 주강에 비하여 자기윤활작용이 있으며, 말차계수가 적어 마찰면의 면입이 높은 경우에도 소손 등의 이상 마멸현상이 적어 진공펌프, 내연기관, 공작 기계등과 같이 강인성과 내마멸성을 요구하는 부품에 많이 이용되어 왔다, 이 회주철도 대별하면 여러 종류가 있고, 진공 펌프용 재질은 주로 회주철 중에 ASTM A형으로 도면에 명기되어 있다. 따라서 본 제품을 개발하는 과정중에 연속 주조법으로 제조된 ASTM형이 기존의 재료에 비하여 내기밀성, 내마면성, 내피로성 및 기계적 성질등이 우수함을 확인하여본 재질로 개발하였고, 시험한 연구 결과를 발표하고자 한다. 실험은 ASTM A형으로 주조하기 위하여 용해된 용탕을 사형 주형에서 GC200으로 주조하고, ASTM D형은 D사의 연속 주조기에서 직경 30mm로 주조하였다. 이와 같이 주조된 사료를 일정한 크기로 시험편을 만들어 인장 강도, 경도, 피로한도, 피로성, 절삭성, 내유압성, 소입성과 내마멸성을 시험하였다.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.167-173
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• 2004

Recently, it has been reported that frictional behavior at nanometer scale can be different from that at macro scale. In this article, friction and wear tests were conducted using an AFM to investigate the effect of real contact area on the coefficient of friction and wear property. SiO$_2$, Hica, and SiGe were used in friction test and the AFM tip was Si$_3$N$_4$. The real contact area between an AFM tip and flat surface was calculated by the Johnson-Kendall-Roberts (JKR) theory. Wear specimen was Mica, and the diamond tip was used. We found that the coefficient of friction is constant below a critical area, but it is degraded over the area. Moreover, it is found that wear depth increased rapidly from a certain load and was degraded as a function of the number of the scanning cycles. Also, the range of scanning velocity used in this study had little effect on the wear depth.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.82-88
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• 2009

A disadvantage in the design of gerotor pump is a lack of parts that can be adjusted to compensate for wear in the rotor set, and as a consequence, it causes a sharp reduction of efficiency. In this paper, an attempt has been made to reduce the wear rate between the rotors of a gerotor pump. To do this, floating genetic algorithm (FGA) is used as an optimization technique for minimizing the wear rate proportional factor (WRPF). The result shows that the wear rate can be reduced considerably, e.g. approximately 8% in this paper, throughout the optimization using FGA.

• Journal of KSNVE
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• v.6 no.6
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• pp.819-825
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• 1996

Nonlinear dynamic characteristics of rubbing phenomenon in rotor dynamics are investigated experimentally and numerically. Rubbing phenomenon occurs when rotor contacts with stator during whirling and causes the large amplitude of vibration, high whirl frequencies, and possibly catastrophic failure. Rubbing has various types of forward whirl, backward rolling, backward slipping, and partial rub depending on the system parameters of rotating machinery and running speed. Experiments are performed for forward whirl and backward whirl. And numerical analysis are conducted to explain the changes between backward rolling and backward slipping. Experimental and numerical results show that the types of whirling motion depends on the friction coefficient between rotor and stator and the eccentricity of rotor.