• 대한기계학회논문집
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• 제15권6호
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• pp.1975-1981
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• 1991

본 연구에서는 완전히 불균일한 격자계를 사용하여 프로파일링을 한 원통형로 울러의 프로파일링 시작점 부근에서의 압력분포 및 유막형상과 함께 무차원변수의 변 화에 따른 최소유막의 거동을 상세히 조사하고자 한다. 이 결과에서 실제 로울리 베 어링의 로울러 프로파일의 설계시에 적용할 수 있는 새로운 기준을 제시하고자 한다.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.137-146
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• 2008

Proper amount of entrained air and nip force should be also considered to minimize ballooning phenomenon since tight contact between a roller and web is required. In this paper, various web materials, PET(Polyester) and OPP(Oriented Poly Propylene) have been selected and investigated to satisfy high-speed printing requirement. Several web speeds, web tensions, and temperature conditions are imposed on each web materials and the pressure and gap profiles as well as nip force have been calculated. Increase of both the winding roller radius and the incoming wrap angle is considered under proper taper tension at 500 m/min of rewinding roller. By solving coupled Reynolds equation and web deflection equation simultaneously, the fluid-structure interaction process has been developed and is applied to the rewinding roller to investigate the ballooning phenomenon which causes guiding problems in high-speed printing performance conditions. By adjusting the linear taper tension, stress distribution between rewinding webs can be remarkably reduced and stable pressure and gap profile with ignorable ballooning phenomenon have been found.

• 한국정밀공학회지
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• 제17권8호
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• pp.113-119
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• 2000

There are two major factors which affect the cam design : the pressure angle and the radius of curvature, Cam shape will have an instantaneous radius of curvature at every point. Even though the design constraint of the pressure angle has been satisfied the follower may still not complete the desired contact motion. If the radius of the follower roller is larger than the concave(negative) radius on the cam it occurs the gap between the cam and the follower roller at the contact point. And also if the curvature of the pitch curve of the cam is too sharp the cam profile may be undercut. This paper proposes a new approach which uses the relative velocity of the follower roller parallel to the tangent line at the contact point on the cam surface for determining the pressure angle and the relative acceeration for determining the radius of curvature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.127-128
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• 2009

• 대한기계학회논문집A
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• 제33권10호
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• pp.1099-1107
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• 2009

Numerical simulation and experimental study to evaluate the critical speed of the railway bogie according to the tread inclination of wheel profile were conducted using 1/5 scale model. It has been shown that the results of the critical speed analysis for the scale bogie model is very close to the test results using scale bogie model and the critical speed is decreased in proportion to the increase of equivalent conicity of wheel profile. Results of this study show that the scale model could be applied to research area relating to vehicle stability as an alternative to overcome the experimental problems caused by full scale test on the roller rig.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.513-518
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• 2001

This research has been performed to estimate the hunting motion hysteresis of railway passenger cars. An old and a new car with almost same structure are chosen as analysis models. To solve effectively a set of simultaneous equations of motion strongly coupled with creep relations, shooting algorithm in which the nonlinear relations are regarded as a two-point boundary value problem is adopted. The bifurcation theory is applied to the dynamic analysis to distinguish differences between linear and nonlinear critical speeds by variation of parameters. It is found that there are some factors and their operation area to make nonlinear critical speed respond to them more sensitivity than linear critical speed. Full-scale roller rig tests are carried out for the validation of the numerical results. Finally, it is concluded that the wear of wheel profile and the stiffness discontinuities of wheelset suspension caused by deterioration have to be considered in the analysis to predict hysteresis of critical speed precisely.

• 조명전기설비학회논문지
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• 제23권2호
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• pp.18-26
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• 2009

광센서 조광제어시스템은 주광을 이용하여 인공조명을 제어하는 대표적인 조명제어시스템이다. 그러나 실내에 설치된 고정된 쉐이딩시스템으로 인해 주광유입을 차단함으로써 광센서 조광제어시스템의 현장 적용성은 낮다. 광센서 조광제어시스템의 적용성 및 정확성의 향상을 위해 자동 롤러쉐이딩 시스템과의 통합은 필수적이다. 따라서 본 연구는 롤러쉐이드의 높이에 따른 주광유입분포의 특성을 분석하기 위하여 Mock-up(1/2스케일) 테스트를 시행하였다. Mock-up은 롤러쉐이드가 설치된 2개의 실과 쉐이딩시스템이 없는 1개의 실로 구성되었다. 롤러쉐이드가 설치된 2개의 실 중 1개소는 롤러쉐이드의 높이를 최하단으로 고정하였고, 다른 1개의 실은 태양의 일영각을 기준으로 직사일광의 실내유입깊이를 정하여 산출된 롤러쉐이드의 높이로 제어하였다.

• 대한기계학회논문집A
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• 제36권11호
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• pp.1391-1397
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• 2012

하이포 트로코이드 기반의 CRG(Cam ring gear) 시스템은 핀 또는 롤러 치형을 가지는 기어와 공액인 캠 링기어로 구성된 내접기어 시스템이다. 본 논문에서는 CRG 시스템의 엄밀 치형설계를 바탕으로 기어 치면에서의 접촉특성을 분석하였으며 형상설계변수인 치형수정계수에 따른 기어의 내구수명을 검토하였다. 결과적으로 치형수정계수의 증가를 통해 기 설계된 CRG 시스템에 영향을 미치지 않으면서 기어의 접촉 피로수명을 향상시킬 수 있다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.123-124
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• 2002

A press shoe is an element of a machine for squeezing water from wood pulp in the field of manufacturing paper. This is used to compress the pulp enveloped by felt sheet with a large roller. The squeezing force is made by hydraulic pressure. The press shoe has a mechanism similar to a partial hydrostatic bearing. The pressure profile between press shoe and roller affects their squeezing ability, and partial peak pressure can tear the wet pulp. The curvature of the surface of press shoe varies to reduce the peak pressure and increase the mean pressure simultaneously. Therefore, the prediction of pressure distribution considering partially changed curvature of hydrostatic bearing is very important for designing the press shoe. In this study, the difference formulation of Reynolds' equation for partial hydrostatic bearing is by direct numerical method and a computer program to calculate the pressure distribution is developed. We investigate the effect of partially changed curvature of bearing surface on the pressure distribution. Other design parameter for hydrostatic bearing such as depth of pocket and relative velocity are also studied.

• KSTLE International Journal
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• 제3권2호
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• pp.90-94
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• 2002

A press shoe is an element of a machine for squeezing water from wood pulp in the field of manufacturing paper. This is used to compress the pulp enveloped by felt sheet with a large roller. The squeezing farce is made by hydraulic pressure. The press shoe has a mechanism similar to a partial hydrostatic bearing. The pressure profile between press shoe and roller affects their squeezing ability, and partial peak pressure can tear the wet pulp. The curvature of the surface of press shoe varies to reduce the peak pressure and increase the mean pressure simultaneously, Therefore, the prediction of pressure distribution considering partially changed curvature of hydrostatic bearing is very important far designing the press shoe. In this study, the difference formulation of Reynolds equation far partial hydrostatic bearing is derived by direct numerical method and a computer program to calculate the pressure distribution is developed. We investigate the effect of partially changed curvature of bearing surface on the pressure distribution. Other design parameter far hydrostatic bearing such as depth of pocket and relative velocity are also studied.