• 대한기계학회논문집A
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• 제41권10호
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• pp.975-981
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• 2017

알루미늄 합금과 같은 경량소재의 적용을 통한 무게 감소는 연료절감과 대기 오염 감소에 기여할 수 있다. 알루미늄 합금 재료는 피로수명에 대한 강도 측면에서 철강(steel) 소재에 비하여 취약한 단점을 가지고 있다. 부품들의 안전성을 희생시키지 않고 자동차 부품 경량화를 이루기 위해 많은 연구자들이 보다 가볍고 강한 서스펜션 링크들에 관한 연구를 진행해 왔다. 본 연구에서는 기존 STKM11A 철강소재로 설계된 토크 스트럿을 245 MPa의 인장강도 소재인 알루미늄 합금(A356) 소재로 대체하기 위한 경량화 설계 과정에 대하여 von-Mises 응력 변화를 분석하여 연구하였다. 최적화된 설계는 경량화 이전 강재로 설계된 링크보다 42% 이상 경량화 시킬 수 있었으며 이는 토크 스트럿 개발의 안전한 경량화 설계조건 및 경량화 설계에 대한 가이드에 참고가 될 수 있을 것이다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권2호
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• pp.287-301
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• 2013

The present paper deals with the problems of yaw angle effects on podded propulsor performance. The study aims at providing insights on characteristics of podded propulsors in azimuthing condition. In this regard, a wide numerical simulation that concerned yaw angle effect measurement on podded propeller performance was performed. The Reynolds-Averaged Navier Stokes (RANS) based solver is used in order to study the variations of hydrodynamic characteristics of podded propulsor at various angles. At first, the propeller is analyzed in open water condition in absence of pod and strut. Next flow around pod and strut are simulated without effect of propellers. Finally, the whole unit is studied in zero yaw angle and azimuthing condition. Structured and unstructured mesh techniques are used for single propeller and podded propulsor. The performance curves of the propeller obtained by numerical method are compared and verified by the experimental results. The characteristic parameters including the torque and thrust of the propeller, the axial force and side force of unit are presented as function of velocity advance ratio and yaw angle. The results shows that the propeller thrust, torque and podded unit forces in azimuthing condition depend on velocity advance ratio and yaw angle.

• 대한기계학회논문집A
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• 제32권2호
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• pp.170-176
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• 2008

Anti roll bar model for real time multibody vehicle dynamics model has been proposed using kinematic constraint. Anti roll bar have been modeled by kinematic relationship, and mass properties are neglected. Relative angle of torsion bar spring is computed by constraint about drop-link using Newton-Raphson iteration, and then the torque of torsion bar spring can be computed with the angle and torsion spring stiffness. Finally anti roll bar force acting on both knuckle can be calculated. To validate the proposed method, half car simulations of McPherson strut suspension and full car simulations are also carried out comparing with the ADAMS vehicle model with anti roll bar. CPU times are also measured to see the real-time capabilities of the proposed method.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.965-980
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• 2014

This paper presents a new estimation method of full scale propulsive performance for the pulling type podded propeller. In order to estimate the drag of pod housing, a drag velocity ratio, which includes the effects of podded propeller loading and Reynolds number, is presented and evaluated through the comparison of model test and numerical analysis. By separating the thrust of propeller blade and the drag of pod housing, extrapolation method of pod housing drag to full scale is deduced, and correction method of propeller blade thrust and torque to full scale is presented. This study utilized the drag coefficient ratio of the pod housing as a measure for expanding it to full scale, but in order to increase the accuracy of performance evaluation, additional study is necessary on the method for the full scale expansion via separating the drag of pod body, strut and fin which consist the pod housing.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.142-153
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• 2005

The brake judder is a phenomenon that the steering wheel is abnormally vibrating when the car is braked at a high speed. It is classified by the cold and the hot judder. The former is generated due to the initial uneven disk surface and the latter is resulted from the uneven heat spots on disc surface by repeatedly braking. There are two ways to reduce the judder. One is to control vibration by modification of the disk shapes and pad ingredients. The other is to improve modal characteristics of the suspension system. The latter approach is used in this research. In this paper, the real vehicle test and computer simulation are considered to systematically understand the judder phenomenon of the vehicle. The Macpherson strut suspension is employed. Especially, the judder sensitivity is calculated based on design sensitivity analysis. A bush stiffness was reworked and braking test was done to verify the sensitivity result. The judder reduction by the mode control was verified.