• Journal of KSNVE
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• v.7 no.3
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• pp.499-509
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• 1997

During the process of oxide removal from work rolls in sheet metal manufacture, filamentary brushes frequently exhibit a bouncing or chatter behavior. The dynamics of this phenomenon is investigated through the development of expressions for the non-linear contact stiffness between the brush and the roll. With formulation of simple structural models, the time responses in the presence and absence of friction under random excitation are investigated. Possible solutions for the minimization or avoidance of this bouncing or chatter problem are also suggested.

• The Korean Journal of Rheology
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• v.3 no.1
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• pp.38-46
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• 1991

저분자량(분자량: 1.04$\times$104 g/mole)과 고분자량(3.84$\times$106) 폴리스타이렌 브렌드를 제조하고 무접촉 무마찰을 이용한 비틀림 크립장치를 사용하여 점도, 크립 캄플라이언스들 을 측정하고 또 지연 스펙트라도 계산해 내었다. 고분자량의 농도는 0, 2, 10, 20, 50, 70, 100 중량 퍼센트였다. 점도는 블렌드의 중량평균 분자량이 임계분자량이상이면 중량평균의 3.5승에 비례했다. 중량평균 분자량>임계분자량 인블렌드의 경우 정상상태 회복 캄플라이언 스는 중량평균의 3.5승에 비례했다. 중량평균 분자량>임계분자량 인 블렌드의 경우 정상상 태 회복 캄플라이언스는 중량평균의 -2.3승에 비례했다. 지연스펙트라를 검토한 결과 폴리 스타이렌의 임계분자량은 38000 g/mole 쯤으로 추정되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5412-5419
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• 2011

The need is growing for high-speed spindle because various equipment are becoming more precise, miniaturization and high speed with the development of industries. Air-lubricated dynamic bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. Air-lubricated dynamic bearing can be used in high-speed, high-precision spindle system and hard disk drive(HDD) because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy. In the paper, numerical analysis is undertaken to calculate the performance of air-lubricated dynamic bearing with herringbone groove. The static performances of herringbone groove bearings which can be used to support the thrust load are calculated. Electrochemical micro machining($EC{\mu}M$) which is non-contact ultra precision machining method has been developed to fabricate the air-lubricated dynamic bearing and optimum parameters which are inter electrode gap size, concentration of electrolyte, machining time are simulated using numerical analysis program.