• Journal of Korean Society of Steel Construction
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• v.12 no.1 s.44
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• pp.103-110
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• 2000

The suspension bridge is divided by an earth anchor and a self-anchor type according to the anchorage type. This study is to evaluate the dynamic effect of moving vehicles to suspension bridges. The results were presented with the dynamic magnification factor (DMF) by the effect of vehicle speed and weight according to the anchorage type. The vehicle model has 6 degrees of freedom to idealize nonlinear multi-leaf suspensions and elastic tires of tractor-trailer. The bridge was modelled with the 3-dimensional frame element and 3-dimensional elastic catenary cable element. The condition of deck surface is considered using the actual road spectra.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.194-202
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• 2015

In this paper, dynamic modeling with viscoelastic properties of a human body resting on a seat is presented to quantitatively analyze ride quality of passengers exposed to vertical vibrations. In describing the motions of a seated body, a 5 degree-of-freedom multibody model from the literature is investigated. The viscoelastic characteristics of seats used in railway vehicles are mathematically formulated with nonlinear stiffness characteristics and convolution integrals representing time delay terms. Transfer functions for the floor input are investigated and it is found that these are different in accordance with the input magnitude due to nonlinear characteristics of the seat. Measured floor input at the railway vehicle is used to analyze realistic human vibration characteristics. Frequency weighted RMS acceleration values are calculated and the effects of the seat design parameters on the frequency weighted RMS acceleration values are presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.383-387
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• 1996

This paper presents a steering control strategy applicable to vehicle path following problems. This control strategy is based on realistic nonlinear equations of motion of multibody systems described in terms of relative joint coordinates. The acceleration of the steering angle is selected as a control input of the system. This input is obtained by considering position and slope errors at current and at advance times. This steering control strategy is tested in circular and lane change maneuvers with a nonlinear vehicle model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4087-4092
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• 2014

The gangway connection of the articulated high speed railway vehicles (HSRV) is a double wrinkled rubber component to seal the air of the corridor under a range of angular deviations between the carriage end parts. From the results of non-linear structural analysis, one of the severe loading conditions for the connection is mixed mode (rolling+yawing) angular displacements while passing through the small-radius curved siding track of the HSRV depot. In this study, to ensure the safety enhancement of the component, the optimal design for the cross section of that was performed using the Solid Isotropic Material with Penalization (SIMP) method. Nonlinear finite element analysis confirmed that the decreases in the maximum principal strain of the optimized design under rolling and mixed modes are 68% and 39%, respectively, compared to the initial design.

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.23-31
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• 2010

Due to the fact that fisheye lens can provide super wide angles with the minimum number of cameras, field-of-view over 180 degrees, many vehicles are attempting to mount the camera system. Not only use the camera as a viewing system, but also as a camera sensor, camera calibration should be preceded, and geometrical correction on the radial distortion is needed to provide the images for the driver's assistance. In this thesis, we introduce a geometric correction technique to minimize the loss of the image data from a vehicle fish-eye lens having a field of view over $180^{\circ}$, and a asymmetric distortion. Geometric correction is a process in which a camera model with a distortion model is established, and then a corrected view is generated after camera parameters are calculated through a calibration process. First, the FOV model to imitate a asymmetric distortion configuration is used as the distortion model. Then, we need to unify the axis ratio because a horizontal view of the vehicle fish-eye lens is asymmetrically wide for the driver, and estimate the parameters by applying a non-linear optimization algorithm. Finally, we create a corrected view by a backward mapping, and provide a function to optimize the ratio for the horizontal and vertical axes. This minimizes image data loss and improves the visual perception when the input image is undistorted through a perspective projection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.266-272
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• 2004

In this paper, an observer-based adaptive controller is proposed to control the longitudinal motion of vehicles. The standard gradient method will be used to estimate the vehicle parameters such as mass, time constant, etc. The nonlinear model between the driving force and the vehicle acceleration will be chosen to design the state observer for the vehicle velocity and acceleration. It will be shown that the proposed observer is exponentially stable, and that the adaptive controller proposed in this paper is stable by the Lyapunov function candidate. It will be proved that the errors of the relative distance, velocity and acceleration converge to zero asymptotically fast, and that the overall system is also asymptotically stable. The simulation results are presented to investigate the effectiveness of the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.154-161
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• 1999

An elastomeric bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer suface. The relation between the force applied to the shaft or sleeve and their relative deformation is nolinear and exhibits features of viscoelasticity. Numerical solutions of the boundary value problem represent the exact bushing response for use in the method for determining the force relaxation function of the bushing. The new nonlinear viscoelastic bushing model, which is called Pipkin-Rogers model, is proposed and it is shown that the predictions of the proposed force-displacement relation are in very good agreement with the exact results. This new bushing model is thus very suitable for use in multi-body dynamics codes. The success of the present study for axial mode response suggests that the same approach be applied to other modes, such as torsional or radial modes.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.419-425
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• 1988

It would be very useful if the dynamic response of a vehicle over rough ground could be predicted at the early design stage. This became more promising with the recent progress in computer hardware and software technologies. In this study, a model of a passenger car has been developed for the analysis of its dynamic response. This model can be easily used for the other passenger cars with little modification. This passenger car was modeled to be composed of lumped masses, rigid bodies, and the suspension systems with nonlinear properties. Even though a commercial dynamic simulation program, ADAMS, was used in this study, the developed model is valid for any other simulation program. Finally, the validity of the developed model and the analysis result was verified by an experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.169-176
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• 2000

Longitudinal and lateral forces acting on tires are known to be closely related to the tract-ability braking characteristics handling stability and maneuverability of ground vehicles. In thie paper in order to develop tire force monitoring systems a monitoring model is proposed utilizing not only the vehicle dynamics but also the roll motion. Based on the monitoring model three monitoring systems are developed to estimate the tire force acting on each tire. Two monitoring systems are designed utilizing the conventional estimation techniques such as SMO(Sliding Mode Observer) and EKF(Extended Kalman Filter). An additional monitoring system is designed based on a new SKFMEC(Scaled Kalman Filter with Model Error Compensator) technique which is developed to improve the performance of EKF method. Tire force estimation performance of the three monitoring systems is compared in the Matlab simulations where true tire force data is generated from a 14 DOF vehicle model with the combined-slip Magic Formula tire model. The built in our Lab. simulation results show that the SKFMEC method gives the best performance when the driving and road conditions are perturbed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.76-81
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• 1994

승용차에 있어 엔진의 공회전시나 주행중에 발생하는 여러 형태의 진동 및 소음의 저감은 승차감 및 차량의 안정성에 있어 중요한 과제가 되고 있다. 이러한 소음, 진동은 주로 엔진에서 발생하는 토크의 비주기적인 변동성분이 클러치(clutch), 변속기(transmission), 구동축을 거쳐 바퀴로 전달되는 과정에서 발생한다. 셔플(shuffle)은 주행중 가속페달(accelerator)을 급조작(tip-in, tip-out)하였을 때 차량이 전후로 과도적으로 울렁거리는 종진동 현상을 말하며, 이것은 가속페달의 급조작으로 인해 엔진토크가 큰 변동을 일으키고, 동력전달계를 통해 타이어에 전달된 이 토오크는 타이어축에서 구동측으로 역토오크를 발생시키기 때문에 발생한다. 여기서 팁-인(tip-in)이란 승용차를 저속으로 운전하다가 갑자기 가속페달을 밟는 경우를 말하며, 팁-아웃(tip-out)은 반대로 고속상태에서 갑자기 가속페달을 떼는 경우를 말한다. 실험과 시뮬레이션을 사용한 자동차 동력전달계의 비틀림 진동에 대한 연구는 이미 여러 연구자들에 의해 보고되었다. H.Arai은 2자유도 비선형 모델을 사용하여 클러치 접속시 발생하는 외란과 계의 안정성을 고려하여 시뮬레이션을 수행하였고, M.Kataoka는 기어의 공차(clearance)를 고려한 변속기의 강제 비틀림 진동을 실험과 시뮬레이션을 통하여 해석하였다. 그리고, Wu Hui-Le는 자동차 동력전달계의 비틀림 진동 현상을 실험과 이론적인 계산을 통해 연구하였고, R.J.Comparin는 치타음의 발생구조와 특성을 고찰하고 비서형 비틀림 공진 저감에 의한 치타음 저감 기법에 대하여 연구하였다. 또한 G.J.Fudala는 다자유도 모델을 이용하여 클러치의 비틀림 특서엥 따라 주파수분석을 수행하여 치타음 저감 방법을 연구하였고, T.Sakai는 5자유도 모델을 이용하여 엔진 공회전시 발생하는 치타음에 대해 이론과 실험을 통해 해석하고, 엔진 회전수 변동, 클러치 특성, 변속기의 드래그(drag) 토크의 영향과 치타음 저감을 위한 개선된 클러치 특성을 제시하였다. 이 외에도 Thomas C.T.와 E.P.Petkus는 특정 차량에 대한 동력전달계의 비틀림 진동 현상에 대해 연구하였다. 이러한 연구들로 볼 때, 자동차 동력전달계에서 발생하는 진동은 이론과 실험을 통해 그 해석이 가능하며 설계에 매우 유용하게 이용되고 있음을 알 수 있다. 따라서, 본 연구는 4 실린더 4 싸이클 1.5 L 엔진을 장착한 경승용차의 실차 주행실험을 통해 가속 페달의 급조작에 따른 차체의 종진동 현상을 측정하고, 엔진-변속기-타이어-차체의 반환정계 4자유도 진동모델로 시뮬레이션을 수행하여 실차 주행실험의 결과치와 비교, 분석한 후 클러치 비틀림 특성을 비롯한 자동차 동력전달계의 각 설계인자들이 차체의 종진동에 어떠한 영향을 미치는가를 해석하고자 한다.