• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.89-102
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• 1997

In this study, the steady state cornering behavior of a vehicle is investigated by using a numerical model that has parameters associated with roll motion. The nonlinear characteristics of tire cornering forces and aligning torques are presented in analytical forms using the magic formula. The sets of nonlinear algebraic equations that govern the cornering motion are solved by the Newton-Raphson iteration method. The vehicle design parameters are measured by SPMD(Suspension Parameter Measuring Device), and its results are verified by carrying out a skid pad test. The design parameters that are most affecting the steady state cornering behavior are classified into four factors, and the contributions of the factors to understeer gradient are then calculated.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.195-206
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• 1997

In this study, a simulation tool is developed in order to investigate non steadystate cornering performance of 4WD/4WS vehicles. The 4WD/4WS vehicles are modeled as a 8-th order dynamic system which includes complex non-linear vehicle dynamics and tire models. The vehicle models are constructed into a modulated simulation tool and are utilized for analyzing cornering performance such as combined braking and steering, cornering on the icy read and $\mu$-split braking, The whole analysis is done with the simulation tool which consists of a number of subsystems and offers graphic environment. Simulation results show that this tool is useful and cost-effective in the dynamic analysis of the combustion-engine vehicles as well as electrically driven vehicles.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.352-359
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• 2003

철도나 고속철도 교량에 사용되는 장대레일은 차량에 의한 동적충격의 완화, 주행시 승차감의 향상과 같은 장점을 가져온 반면에, 인접한 교량의 연결부에서 레일과 교량 상부구조간의 거동 불일치로 인해 레일에 부가적인 응력을 발생시킨다. 이러한 부가적인 레일응력과 지반운동의 특성에 따른 구조적 응답의 민감도 및 열차의 안전한 정지를 고려하여, 지진 발생시 고속철도교량의 장대레일 응력을 해석하기 위해 레일의 재료비선형성, 지반운동의 위상차 등을 고려한 비선형 시간이력해석 방법을 제시하였다. 그리고 우리나라의 여러 지반조건을 고려하고 고속철도의 대표적인 연속교량 모델에 적용하여 제시한 방법의 타당성을 검토하였다.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.15-18
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• 2006

도로의 정보를 취득하기 위하여 제작된 도로 안정성 조사 분석 차량(RoSSAV)은 도로의 3차원 정보를 취득하는 한 방법으로 레이저 스캐너를 사용한다. 레이저 스캐너로부터 취득된 도로의 3차원 정보는 많은 목적으로 활용할 수 있는 매우 유용한 정보이나, 도로의 3차원 정보를 사용자가 육안으로 확인할 수 있도록 영상으로 편집을 하게 되면, 현실감 있는 영상이 생성되기는 어렵다. 이를 보완하기 위하여 본 연구에서는 레이저 스캐너로부터 얻은 정보와는 별도로 CCD 카메라로 도로 전방 영상을 촬영하였고, 이 두 가지 데이터를 합성하여 현실감 있는 3차원 도로영상을 생성하는 기법을 연구 개발하였다. 레이더 영상과 CCD 영상의 합성은 레이저 데이터가 가지고 있는 3차원의 위치에 해당하는 CCD영상에서의 영상점을 찾아 이 점에서의 RGB 밴드의 밝기값을 찾아내어 이를 레이저 데이터에 기록, 적용시키는 것을 의미한다. 이 방법을 사용하기 위해서는 영상간의 관계모델을 수립할 필요가 있으며, 본 연구에서는 직접선형변환(DLT) 모델을 사용하였다. 이 모델을 이용하기 위해 레이저 데이터를 영상으로 편집하였고 이 영상과 CCD영상과 일치하는 지점을 육안으로 찾아 각 영상별로 DLT센서모델에 필요한 개수의 기준점을 제작하여 실행하였다. 실험 결과 영상은 기준점의 정확도에 따라 약간의 차이는 있으나 합성 전의 레이저 데이터 영상에 비해 실세계에 가까운 색깔을 나타냄이 확인되었다.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.320-328
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• 2017

In order to analyze the influence on derailment safety according to the aging of primary rubber springs widely applied to railway vehicles, characteristic tests were carried out on aged primary rubber spring samples. To analyze the effect of primary rubber spring aging on derailment safety, a vehicle dynamic analysis was carried out. The results of the vertical characteristics test for the rubber spring specimens with 17 years of service life revealed that the displacement restoration function was degraded due to rubber aging and the spring stiffness significantly increased. The results of the running dynamic analysis simulating the twist track running in accordance with the EN14363 standard, compared with the normal vehicle model (Case 1), showed that the derailment coefficient and the wheel unloading of the vehicle model (Case 2) using the aging primary spring characteristic increased, and the derailment safety was degraded. IN particular, it was found that the derailment safety due to the reduction of the wheel load is weak in the transient section where a steep slope change occurs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.82-88
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• 2018

This study investigated the structure of an 8-pole 8-slot linear generator, which acts as an electromagnetic damper by combining the structure of an electromagnetic suspension device capable of generating electrical energy through energy harvesting by absorbing the vibration energy from the road surface while driving. To compare the energy harvesting effect of the electromagnetic suspension according to the actual road surface, a driving road test was simulated for two actual road conditions, an asphalt road surface and unpacked road surface condition, using a civilian combined vehicle model in conjunction with a vehicle simulation program, Carsim and Simulink. As a result, the relative displacements of the suspensions on the asphalt road surface and the unpaved road were 8 mm and 13 mm, respectively. By applying the suspension displacement value derived by modeling the linear generator coupled to the electromagnetic suspension, the simulation was then performed for an analysis time of 0.3s by applying the same analytical conditions using the commercial electromagnetic analysis program, ANSYS MAXWELL, The average power generation on the unpacked roads and asphalt roads was 198.6W and 98.7W respectively, which was 103.7% higher for unpackaged roads. Finally, to compare the sensitivity of the road surface frequency and the suspension input displacement to the power generation output, the sensitivity of the two variables was 1.725 and 1.283, respectively, and the road surface frequency had a 34.5% higher effect on the average power generation.

• Journal of Korean Society of Transportation
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• v.23 no.1
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• pp.33-44
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• 2005

Railroad crossing crashes are fewer than road crashes, but with regard to crash severity, they can be serious injury crashes. There should be, therefore, enormous efforts to increase the safety of railroad crossings. The objective of this paper is to identify and understand factors associated with railroad crossing crashes. Statistical models are used to examine the relationships between crossing accidents and geometric elements of crossings. The results show the Poisson model is the most appropriate method for the crossing accidents, because overdispersion was not observed. This study identifies seven significant factors associated with railroad crossing crashes through the main and variant models. With regard to explanatory factors on crossing safety, the total traffic volume, daily train volume, presence of commercial area around crossings, distance of train detector from crossings, time duration between the activation of warning signals and gates, crossing types, and speed hump were found to affect the safety of railroad crossings.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.525-526
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• 2008

For measuring nonlinear Vehicle Modeling based on 7-Depth Sensor, the neural networks are proposed m adaptive and in realtime. The structure of it is similar to recurrent neural networks; a delayed output as the input and a delayed error between the output of plant and neural networks as a bias input. In addition, we compute the desired value of hidden layer by an optimal method instead of transfering desired values by backpropagation and each weights are updated by RLS(Recursive Least Square). Consequently, this neural networks are not sensitive to initial weights and a learning rate, and have a faster convergence rate than conventional neural networks. This new neural networks is Error Estimated Neural Networks. We can estimate nonlinear models in realtime by the proposed networks and control nonlinear models.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.233-237
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• 2002

Vehicle Dynamics Control(VDC) has been a breakthrough and become a new terminology for the safety of a driver and improvement of vehicle handling. This paper examines the usefulness of a brake steer system (BSS), which uses differential brake forces for steering intervention in the context of VDC. In order to help the car to turn, a yaw moment can be achieved by altering the left/light and front/rear brake distribution. The steering function achieved through BSS can then be used to control lateral position in an unintended road departure system. A 8-DOF non-linear vehicle model including STI tire model will be validated using the equations of motion of the vehicle, and the non-linear vehicle dynamics. Since Fuzzy logic can consider the nonlinear effect of vehicle modeling, Fuzzy controller is designed to explore BSS feasibility, by modifying the brake distribution through the control of the yaw rate of the vehicle. The control strategies developed will be tested by simulation of a variety of situation; the possibility of VDC using BSS is verified in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.843-850
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• 2020

The purpose of this study is to evaluate the structural risk and weakness of a railway tank car through nonlinear collision analysis according to overseas collision safety standards. The goal is to propose a crash safety design guideline for railway tank cars for transporting dangerous goods in Korea. We analyzed the buffer impact test procedure of railway freight cars prescribed in EN 12663-2 and the tank puncture test criteria prescribed in 49CFR179. A nonlinear finite element model according to each standard was modeled using LS-DYNA, a commercial finite element analysis solver. As a result of the buffing impact test simulation, it was predicted that plastic deformation would not occur at a collision speed of 6 km/h or less. However, plastic deformation was detected at the rear of the center sill and at the tank center supporting the structure at a collision speed of 8 km/h or more. As a result of a head-on test simulation of tank puncture, the outer tank shell was destroyed at the corner of the tank head when 4% of the kinetic energy of the impacter was absorbed. The tank shell was destroyed in the area of contact with the impacter in the test mode analysis of tank shell puncture when the kinetic energy of the moving vehicle was reduced by 30%. Therefore, the simulation results of the puncture test show that fracture at the tank shell and leakage of the internal material is expected. Consequently, protection and structural design reinforcement are required on railway tank cars in Korea.