• International Journal of Railway
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• 제2권2호
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• pp.43-49
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• 2009

Wear and rolling contact fatigue (RCF) defects are most important causes of rail damage, and often interaction competitive at present railway track. Head check is one of rolling contact fatigue (RCF) defects, and generally occurs in mild circular curves and transition curves that are set at both ends of sharp circular curves. Wear tends to limit the crack growth of head checks by removing the material from the RCF surface. In order to clarify the conditions of the occurrence and growth of head checks, the authors measured the interacting forces between wheels and rails and the angle of attack of wheelset, and carried out contact analyses using the actual profile data of wheels and rails. The effects of the lateral force, the contact geometry, and the wear rate at rail gauge comer on the formation of head checks were also analyzed by using the worn profiles of actual wheels and rails and the data obtained by a track inspection car. Some specific range of wear rate at the gauge comer was identified as having close relation with occurrence of head checks.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.357-361
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• 1997

In this work surface damage of head and disk of head disk drive was analysed using an Atomic Force Microscpoe. The initial damage of the disk occurred by generation of extermely small wear particles. Also it was show that wear particles tend to pile up near the front side of the slider. The surface damage mechanism of drag test and contact-start-stop test was found to be quite similar.

• 한국정밀공학회지
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• 제15권9호
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• pp.167-174
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• 1998

In this work the surface damage of head and disk of a hard disk drive was analysed using an Atomic Force Microscope. The initial damage of the disk occurred by generation of extremely small wear particles. Also it was shown that wear particles tend to pile up near the front side of the slider. The surface damage mechanism of drag test and contact-start-stop test was found to be quite similar.

• Tribology and Lubricants
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• 제25권5호
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• pp.330-334
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• 2009

Hydraulic servo cylinders have been used to control accurately a large machine in power plant. Especially, Piston head and bush of servo cylinder is assembled sleeve and piston head and bush made of Cu alloy and pad sealing part. A damages of sleeve and piston head, bush are caused by friction and wear. Thus, It is necessary to examine friction and wear characteristics of Cu alloys for the piston head and bush. In this study, to be reliable on the piston and cylinder parts, dry friction and wear experiments were carried out with Cu alloys of four kinds of AlBC, PBC, BC and BS using reciprocating friction tester of pin on disk type. From this study, the result was shown that the AlBC and PBC with alloy elements were excellent to resistance wear. As the sliding speed was increased, the wear loss of PBC decreased than another Cu alloy.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.339-344
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• 1999

In this paper, the hardness and wear characteristics of the head hardened rail, which is made by thermite and gas pressure weldings have been presented. In general, the wear rate of the gas pressure welded rail is high and uniform compared with that of thermite welded rail. The results indicate that HH 370 welded rail shows stable in hardness and low wear rate compared with other two welded rails. The hardness of head hardened rails shows uniformly distributed along the welded zone, thermally affected zone and a base matrix.

• 보존과학회지
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• 제29권1호
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• pp.15-24
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• 2013

울산시 북산동 출토 고려시대 칠사관모(漆紗冠帽)는 복식사적으로 상당히 귀한 유물로 고려시대 당시의 관모형태를 알 수 있어 역사적 문화적 사회적 예술적으로 사료적 가치가 큰 귀중한 자료라고 할 수 있다. 또한 본 유물은 상대적으로 유물이 부족한 고려시대의 실증적 정보를 제공하는 자료로 발굴 작업에 의한 출토품이라는 점에 의의가 있다. 본 연구에서는 오랜 시간동안 다양한 환경요인에 의해 영향을 받아온 유물의 보존처리를 통해 본래의 상태로 회복시키고 원형을 보존하고자 하였다. 그 결과, 실존유물이 상대적으로 부족한 고려시대 관모의 원형을 보존할 수 있었으며, 재질 및 구조분석을 통해 섬세한 사(紗)조직의 표면조직과 죽사(竹絲)로 제작된 바탕조직을 확인할 수 있었다.

• Tribology and Lubricants
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• 제27권2호
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• pp.65-70
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• 2011

The power servo cylinder for driving accurately turbine stop valve of an atomic power plant is necessary to do turn-over owing to a leakage of oil and a structure problem, especially, it of a power plant be in demand a high quality standard depends entirely on import. There are much problem that the AlBC be to used as a material of piston head in cylinder are caused by wear. Therefore, it is necessary to examine friction characteristics of it. In this study, wear test experiments was carried out with AlBC and SCM440, using reciprocating friction tester of pin on disk. This result was shown that the wear mechanism of AlBC on working condition is adhesive wear and the maximum temperature of infra redray thermal image of frictional surface show over 2 mm from contact surface of pin and disk.

• Journal of Mechanical Science and Technology
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• 제15권11호
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• pp.1524-1532
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• 2001

The effects of recirculated exhaust gas on the wear of cylinder liner and piston were experimentally investigated by a two-cylinder, four cycle, indirect injection diesel engine operating at 75% lo ad and 1600 rpm. For the purpose of comparison between the wear rates of the two cylinders with and without EGR, the recirculated exhaust gas was sucked into one of two cylinders after the soot in exhaust emissions was removed by an intentionally designed cylinder-type scrubber equipped with 6 water injectors(A water injector has 144 nozzles of 1.0 mm diameter), while only the fresh air was inhaled into the other cylinder. These experiments were carried out with the fuel injection timing fixed at 15.3$^{\circ}$ BTDC. It was found that the mean wear rate of cylinder liner with EGR was greater in the measurement positions of the second half than those of the first half, that the mean wear rate without EGR was almost uniform regardless of measurement positions, and that the wear rate of piston skirt with EGR increased a little bit, but the piston head diameter increased, rather than decreased, owing to soot adhesion and erosion wear, and especially larger with EGR.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.345-353
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• 1999

This paper presents friction and wear related results of thermite and gas pressure welded rails under various environmental contact conditions. A welded rail which is manufactured by thermite welding and gas pressure one has been tested rail full range of test conditions in a pin-on-disk wear testing machine. The results show that the friction coefficient and wear rates of a welded rail are heavily dependent on the contact pressures and sliding environments for two welding methods such as thermite and gas pressure weldings.

• International Journal of Railway
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• 제7권3호
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• pp.65-70
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• 2014

In this paper, the reduction effect of dry (solid) lubrication on wheel flange wear rates is studied. The solid / dry lubricator systems were attached to the most front and furthest back axles of a coach in order to examine the wear behavior of the equipped wheels. An attempt is also made to make a comparison between wear behaviors of these wheel flanges having dry lubrication devices with non-lubricated wheels in other railcars. Finally, a comparison is made between life-cycle of wheels under investigation and other similar wheel types.