• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.931-932
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.553-554
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1021-1022
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• 2010

• Journal of Drive and Control
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• v.7 no.1
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• pp.33-37
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.399-400
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• 2007

• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.23-27
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• 2015

The stress and deformation behavior safeties of cylindrical hollow rollers have been analyzed by the finite element method, and investigated for over design capability based on the computed results. According to the stress analysis result which is related to the strength of a hollow roller, the maximum stress of 39.8MPa in which is operated near the bearing for supporting a hollow roller structure is overestimated design as 15.9% level compared with a yield strength, 250MPa of a steel material. And the maximum deformation of 0.032mm in which is operated at the middle span of a total length of cylindrical hollow rollers is very small and sufficiently safe compared with a total length and a thickness of a hollow roller. Thus, the FEM computed results for a stress and deformation indicate that a current FEM analysis model of cylindrical hollow rollers is over designed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.84-88
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• 2008

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by appling the most efficient detecting methods and verified the system's reliability through experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.268-273
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• 2009

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by applying the most efficient detecting methods and verified the system's reliability through experiments.

• Tribology and Lubricants
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• v.35 no.4
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• pp.237-243
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• 2019

Through this study, we investigate the effects of ultrasonic nanocrystal surface modification (UNSM) technology on the fatigue life of needle roller bearings. The fatigue life of untreated and UNSM-treated needle roller bearings is evaluated using a roller fatigue tester at various contact stress levels under oil-lubricated conditions. We can ascertain that the fatigue life of an UNSM-treated needle roller bearing was extended by approximately 34.3% in comparison with an untreated one, where the effectiveness of UNSM technology diminishes with increasing contact stress. The surface roughness and surface hardness of needle roller bearings before and after being treated by UNSM technology are compared and discussed to understand the role of UNSM technology in improving the fatigue life of needle roller bearings. In addition, a fractograph of the damaged bearings is observed using a scanning electron microscopy to shed light on the fracture mechanisms of bearings under different contact stress levels. We can therefore conclude that the application of UNSM technology to the needle roller bearings improves the fatigue life by reducing the friction coefficient and increasing the wear resistance; this may be attributed to a reduction in surface roughness from 0.5 to $0.149{\mu}m$ and an increase in surface hardness from 58 to 62 HRc.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.125-127
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• 2007

에어 베어링은 높은 강성과 낮은 마찰력과 같은 장점들로 인하여 높은 정밀도를 요구하는 반도체나 디스플레이 장비의 선형 스테이지에 주로 사용 되어지고 있다. 하지만 현재까지 높은 정밀도를 요구하는 회전형 스테이지에는 아직까지 크로스 롤러링을 이용하여 가이드를 하고 있다. 본 논문에서는 높은 정밀도를 갖는 회전 스테이지의 설계를 위하여 구동 성능과 오차요소에 대한 성능에 대해 설계 목표를 제시 하였고 이러한 스테이지를 구현하기 위해 에어베어링을 적용한 회전형 스테이지를 설계하였다.