• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.603-610
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• 2016

Over 12 years have passed since the first commercial operation of a Korean high-speed train. Since then, the transport capacity of the high-speed lines has become almost saturated. Therefore, studies have been carried out to increase the operating speed of the trains in order to increase their transportation capacity. This study was carried out to improve the critical speed of the KTX-Sancheon, Korean high-speed train, in order to increase its operating speed. A dynamic analysis of the KTX-Sancheon train was performed using the contact data obtained from the wheel wear profiles that were measured from a KTX-Sancheon train in commercial operation. The analysis results were verified by comparing them with the measurement acceleration data obtained from KTX-Sancheon. The suspension parameters were optimized to improve the operation speed. The critical speed of KTX-Sancheon was increased by 9.4% after the optimization by the response surface method. The optimized suspension parameters are expected to be used for the new bogie design to increase the operating speed of KTX-Sancheon from 300km/h to 350km/h.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.91-98
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• 2017

This study was conducted to optimize the spring constant and the damping coefficient, which are design parameters of the tractor cabin suspension system, to minimize the ride vibration. A 3D tractor MBD (multi-body dynamics) model with a cabin suspension system was developed using a dynamic analysis program (Recurdyn). Using the developed model and optimization algorithm, the spring constant and the damping coefficient, which are the design parameters of the cabin suspension for the tractor, was were optimized so thatto minimize the maximum overshoot for the vertical displacement of the cabin was minimized. The percent maximum overshoot of the tractor cabin was simulated for the 13 initial models, which were obtained using the ISCD-II method, and for the 3 additional SAO models presented in the optimization algorithm software. The model that represents with the smallest percent maximum overshoot among the 16 models was selected as the optimized model. The percent maximum overshoot of the optimized model was about approximately 5% lower than that of the existing model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.10a
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• pp.99-105
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• 1993

본 연구에서는 세탁통 및 감속장치가 스너버(Snubber)와 지지 스프링에 의 해서 지지되는 하부지지형 세탁기를 모델로 선택하였으며, 시스템의 동특성 해석을 위하여 세탁기를 회전체를 갖는 강체 현가 시스템으로 모델링하고 운동방정식을 구하여 수치 해법을 적용하여 진동 특성을 계산하였다. 세탁기 의 진동 형태를 예측하기 위해서 밑판의 마찰 계수, 스터버의 곡률 반경, 지지 스프링 계수 및 위치 등을 진동량에 영향을 미치는 설계 변수로 선정하여 결과를 구하였으며, 이 자료들을 설계 변경시에 이용할 수 있게 하였다.

• Journal of Drive and Control
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• v.15 no.4
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• pp.74-80
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• 2018

A damper is a hydraulic device designed to absorb or eliminate shock impulses which is acting on the sprung mass of vehicle. It converting the kinetic energy of the shock into another form of energy, typically heat. In a vehicle, a damper reduce vibration of car, leading to improved ride comfort and running stability. Therefore, a damper is one of the most important components in a vehicle suspension system. Conventionally, the design process of vehicle suspensions has been based on trial and error approaches, where designers iteratively change the values of the design variables and reanalyze the system until acceptable design criteria are achieved. Therefore, the ability to tune a damper properly without trial and error is of great interest in suspension system design to reduce time and effort. For this reason, a many previous researches have been done on modeling and simulation of the damper. In this paper, we have conducted optimal design process to find optimal design parameters of damping force which minimize a acceleration of sprung mass for a given suspension system using genetic algorithm.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.1-8
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• 2006

In this paper, an optimum design technology is developed to find an optimal position of the shock absorber using ADAMS and VisualDOC. A vehicle with a torsion-beam rear suspension is modeled by using ADAMS. Design variables for the optimal positioning of the shock absorber are defined considering the hard points of the chassis structure and design positioning are specified through the sensitivity analysis using a bump-crossing simulation. The objective function is defined as the joint reaction forces of the shock absorber connecting joints of the chassis structure. Sequential Quadratic Programming and Genetic Algorithms are used for this study. To validate the optimized design variables, pothole simulations are performed. GA showed better results than SQP algorithms for this design purpose.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.202-205
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• 2009

Tubular torsion beam of high strength steel is going about in an automotive rear axle due to the advantages of light weight and efficient rear packaging capability. High strength tubular beam can be manufactured by the hydroforming in order to ensure dimensional accuracy, while a conventional stamping has been used for steel tubular beam. Internal pressure, feeding and their combination are the key factors of controlling the process. Based on the numerical simulation and try-outs, the optimized hydroforming process conditions for the high strength tubular beam were suggested.

• Transactions of Materials Processing
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• v.17 no.7
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• pp.481-485
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• 2008

The subframe type rear suspension consisting of a side member and a front/rear cross member is widely used in a medium car and full car. In the small car case, the beam of tubular type without independent suspension system is used to reduce manufacturing cost. In this study, a subframe type rear suspension by hydroforming has been developed. In designing suspension, a driving stability and durability should be considered as an important factor for the performance improvement, respectively. Thus, we focus on increasing the stiffness of suspension and decreasing the maximum stress affecting a durability cycle life. Several optimization design techniques such as shape, size, and topology optimization are implemented to meet these requirements. The shapes of rear suspension obtained from optimization are formed by using hydroforming process. Through commercial software based on the finite element, the superiority of this design method is demonstrated.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.247-259
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• 1996

Kinematic design sensitivity analysis for vehicle in suspension systems design is performed. Suspension systems are modeled using composite joins to reduce the number of the constraint equations. This allows a semi-analytical approach that is computerized symbolic manipulation before numerical computations and that may compensate for their drawbacks. All the constraint equations including design variables are derived in symbolic equations for sensitivity analysis. By directly differentiating the equations with respect to design variables, sensitivity equations are obtained. Since the proposed method only requires the hard point data, sensitivity analysis is possible in suspension design stage.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.121-132
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• 1996

As a new suspension is being designed, the designer should consider that the vehicle has a good ride and handling performance. It is not easy for a yound desigineer to decide the design parameters. In this study, the design process of a suspension system is described. the method of optimized design to achieve the target of vehicle performance from the initial layout to detailed design stage is also described. As a result, the effects of design parameters in the vehicle dynamic performance are mentioned by the synthesized program

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.43-53
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• 1998

This paper addresses an optimization for reducing a steering error of a rack-and-pinion steering linkage with a MacPherson strut independent front suspension system. The length, orientations and inner joint positions of a tie-rod are selected as design variables and Ackerman geonetry, understeer effect, minimum turn radius, wheel alignment and packaging are considered as design constraints. Nonlinear kinematic analysis of the steering system is performed for calculating the values of cost and constraints, and Augmented Lagrange Multiplier(ALM) method is used for solving the constrained optinization problem. The optimization results show that the steering error are considerably reduced while satisfying all the constraints.