• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.251-256
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• 1999

"Ploughing" on the flank face of the tool in the metal cutting process is due to the tool in the metal cutting process is due to the finite edge radius of the tool and due to the development of flank wear. Because of the high stresses near the cutting edge, elastic-plastic deformation would be caused between the tool and the machined surface over a small area of the tool flank. The deformation would affect the roughness of the machined surface. Recently, some attempts have been made to predict the surface roughness, but elastic-plastic effect due to ploughing in the cutting process has not been considered. The research has analyzed mechanism of the ploughing of the cutting process using contact mechanics. Tool and workpiece material properties have been taken into account in the prediction of the surface roughness. The surface roughness has been simulated by the surface-shaping system. The results between experiment and simulation have been compared and analyzed. analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.833-836
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• 2007

Load/Unload technology has more benefits than the conventional CSS technology. However, it remains unsolved technical problem on the unloading process. While the slider climbs up the ramp at the outer edge of the disk, the possibility of the slider-disk contact by lift-off force and rebound of the slider increases. This paper focuses on no slider-disk contact. To prevent the slider-disk contact, we apply the disk bump on disk outer edge proceeding unload. Firstly, in the simulation, the bump dimension is determined by changing bump design parameters. Secondly, dynamic stability of slider have to be checked on disk bump before unload analysis, and unload analysis is performed by applying stable bump shapes to unload simulation. Thirdly, we select optimal bump shape to improve unload performance by unload analysis. Finally, in the experiment, the disk bump is mechanically manufactured by pressing disk surface using diamond tip. That is variously processed by changing pressing pressure. After confirming bump shape by nano-scanner, proper bump shape is applied to real experimental unload process. Through this investigation, we propose the optimal bump design to prevent the slider-disk contact, and then we can realize improved unloading performance.

• Tribology and Lubricants
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• 제23권5호
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• pp.187-194
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• 2007

The profile of the roller in the axial direction is the main design factor in order to increase endurance life against the contact fatigue due to the stress concentration along the edge of the roller. Even under the elas-tohydrodynamic lubrication (ehl) conditions, the stress concentration along the edge of the roller greatly worsens the fatigue life both for the roller and contacting body. In this study, roller contacts of finite axial length are studied for the film thickness and pressure of ehl. For the real contact behaviors under the ehl conditions, multigrid and multi-level method is applied so that much higher loading conditions can be investigated. Several axial profiles of roller are investigated to verify how both ehl film and pressure are generated and some of them are recommended for the ehl contact condition.

• Tribology and Lubricants
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• 제6권1호
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• pp.116-125
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• 1990

An experimental programme was established to determine the wear behaviour of TiN coatings of thickness 1 $\mu$m and 3 $\mu$m. by PECVD with the variation of applied load, sliding velocity and sliding distance. It was shown that oxidation of transferred metal as sliding speed increased formed oxide film so that it contributed in decreasing the wear rate. With the roller-on-disc tribometer employed, the wear rate of the roller specimen was decreased with the increase in sliding distance due to the reduction in effective contact pressure. Finally, the severe cracks concentrated at the trailing edge of contact surface were explained in terms of high tensile stress prevailing at the trailing edge of the contact and were identified as a dominant wear mechanism as well as the strong local welding between coating layer and the counter surface, leading to the debonding of the coating layer.

• Tribology and Lubricants
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• 제25권6호
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• pp.427-431
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• 2009

When a bearing roller is in contact with race ways. excessive pressure peaks occur at the ends of the contact region. They are called edge loading. In this study, a method to determinate crowning quantity of the tapered roller bearing which considers tilting. This method is based on contact analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.501-505
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• 1996

In CMM system, a contact probe is not applicable to very small, or flexible elements. There is need to develop non-contact probes of CCD camera. But non-contact probes have some technical problems, including distortion, user interface and time delay. This development gives the foundation of the non-contact probe system and some useful solutions for the problems. The results can be useful for industry application.

• Tribology and Lubricants
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• 제11권4호
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• pp.53-57
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• 1995

The contact pressure behavior is examined by means of a finite element analysis. The oil film between the piston ring and cylinder liner is analyzed on the basis that it behaves like a polymer material. The calculated results indicate that a shape of sloping edge with a straight line, which is designated as a Model III, shows a good performance on the contact pressure behavior for the increased speed. Obviously, the ring face profiles play an important role on the contact pressure between compression ring and oil film.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.76.1-76.1
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• 2010

Furnace를 이용한 $POCl_3$ 확산 공정은 실리콘 태양전지 제작과정에서 일반적으로 이용되는 에미터 층 형성 공정이다. 하지만, 확산 공정을 통해 P-N Junction을 형성할 경우 전면과 후면의 contact현상이 발생하게 되고 이를 제거하기 위해 Edge isolation 공정을 거치게 된다. 최근에는 레이저로 V 모양의 홈을 형성하는 방법이 이용되고 있다. 본 연구에서는 p-type 실리콘 웨이퍼 기판에 insulating barrier를 형성하여 edge isolation 공정을 없앤 Non-edge isolation공정을 제시한다. Non p-type 실리콘 웨이퍼에 insulating barrier를 형성한다. Insulating barrier가 형성된 BOE용액과 KOH에서의 견딤성 실험을 진행 하였다. 이후, p-type 단결정 실리콘 태양전지의 확산 공정을 진행하여 Non edge isolation 공정을 진행한 경우와 laser를 이용한 edge isolation 공정을 진행한 태양전지를 제작하여 특성을 비교하였다.

• KSTLE International Journal
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• 제2권2호
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• pp.85-92
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• 2001

The variation of contact traction induced by different contact shapes is studied experimentally and theoretically. Considerations fer the contact shape are rounded, truncated and truncated with rounding punches. A fretting wear experiment is conducted with the contact configuration of the strip on the tube specimens. The strip specimen is pressed to form the end profile of a rounded and truncated with rounding punches shape. Wear on the tube is investigated, which is regarded as the slip region of the contact surface. Taken into consideration is the general solution of the normal traction in the case of the indentation by a punch with its end profile of the combination of parabolas. Then, partial slip solution is obtained numerically, which is compared with the wear on the tube. The radius of the rounding and the obliquity of the edge truncation affect the tractions considerably. It is found that the proper choice of the end profile can restrain the contact-induced failure such aswear.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1068-1073
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• 2003

Method for contact failure mitigation is studied in this paper. The focus is laid on the contact shape that eventually influences the internal stresses. Contact mechanics is consulted within the frame of plane problem. Hertzian contact, rounded punch and uniform traction profiles are considered. Frictional as well as frictionless contact is also considered. As results, the higher traction profile induced by the rounded punch reveals the greatest among the considered shapes. Therefore, it is suggested to increase the edge radius as large as possible if a contact body of punch shape needs to be designed. It is also found that uniform traction cannot always provide the solution of contact failure mitigation.