• 한국자동차공학회논문집
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• 제6권2호
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• pp.220-227
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• 1998

In substitution of beam-nonlinear spring model for real-car, it may have errors due to complicated characteristics of joint and overestimation of joints stiffness. In this research, a method for the joint modeling was suggested by nonlinear static and dynamic analyses of beam and shell joint models and verified by the application of accomplished joint modeling method to simplified full car model. In consequence, modified simplified full car model was improved in local acceleration and rigid wall force. Finally, the frontal crash analyses with the dummy were established and the accelerations of accelerations of head, chest and pelvis had good agreements with those of shell model.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1074-1079
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• 2011

This paper describes the influence on the nonlinear critical speed results of a specific railway vehicle depending on various constraint conditions. In the roller-rig tests, proper constraints are inevitable to safely hold the test vehicles. Particularly, the test results using KRRI roller-rig are more sensitive to constraint conditions because it is a kind of semi-full car type. In this study, nonlinear critical speed of specific vehicle with regards to several constraint cases were predicted by computational analysis and these results were compared to find the suitable constraint conditions. And also the deviation of semi-full car model from actual full car model was investigated. According to the bifurcation analysis, the nonlinear critical speed are dependent with the constraint condition and car-body yaw motion should be free to achieve more accurate results. And the difference between semi-full and full car model was so small that KRRI's semi-full car model are valid as long as the stability is concerned.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.162-171
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• 1999

The most important part in automated transport systems is steering control for lane keeping Most of systems developed so far have used the visual information for steering control. In this study, the steering control algorithm based on visual servoing has been developed and tested by applying it on Radio Controlled(R/C) model car equipped with one CCD camera. We also demonstrated the feasibility of using it as a pre-test car before the real car experiment in developing automated vehicles. In order to solve the problem of the limited spave and load of a model car, remote-brained approach has been taken. For steering control of a model car, the PD controller which uses the look ahead offset to generate control input has been implemented and the characteristics of the controller has been explained in view of kinematics. Some experimental results have been also illustrated so as to show the control performance and stability.

• 한국기계가공학회지
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• 제19권1호
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• pp.56-62
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• 2020

The purpose of this study is to observe the visualization of the flow field for air flow distributed in the car from the ventilation fan installed in the ceiling of the passenger elevator car through the numerical analysis using computational fluid dynamics. STAR-CCM+, which is a code used for the numerical analysis, was used to predict the airflow distribution inside the elevator car. The numerical analysis of the distribution of the air current in the elevator was carried out. As a result, the analysis results for each point and the visualization of the air current distribution and the temperature distribution in the elevator car and were obtained. It was found that heat transfer was actively occurring inside the car due to the influence of the flow field discharged from the ventilation vent installed in the ceiling in the elevator car, and especially the convection heat transfer of Model-2 was more active than that of Model-1. As a result, the temperature distribution inside the car was found to be relatively low. In addition, the temperature distribution at a cross-section of 1700mm height in the elevator car shows that Model-2 is the location of the ventilation vent which makes people feel more comfortable.

• 서비스연구
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• 제14권1호
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• pp.27-43
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• 2024

중고차 시장에서 온라인 플랫폼 서비스의 시장 점유율은 지속적으로 증가하고 있다. 또한 중고차 온라인 플랫폼 서비스는 서비스 이용자에게 차량의 제원, 사고 이력, 점검 내역, 세부 옵션, 그리고 중고차의 가격 등을 공개하고 있다. 2023년 현재 국내 자동차 시장에서 SUV 차종의 신차 점유율은 50% 이상으로 확대되었으며, 하이브리드 차종은 신차 판매량이 지난해에 비해 두 배 이상 증가하였다. 이에 따라 이들 차종은 국내 중고차 시장에서도 인기를 끌고 있다. 기존 연구는 전체 차량 또는 브랜드별 차량을 대상으로 머신러닝 모델을 실행하여 중고차 가격 예측 모델을 제안하였다. 반면 국내 자동차 시장에서 SUV와 하이브리드 차종의 인기는 매년 상승하고 있으나, 이들 차종을 대상으로 중고차 가격 예측 모델을 제안한 연구는 찾기 어려웠다. 본 연구는 국내 시장에서 자국 브랜드가 생산한 세단, SUV, 그리고 하이브리드 차종을 대상으로 차량 제원과 옵션, 총 72개의 특성을 활용하여 이들 차종별 가장 우수한 중고차 가격 예측 모델을 선정하였다. 이를 위해 특성 선택으로 Lasso 회귀 모델을 활용하여 특성을 선별한 후 동일 샘플링으로 앙상블 모델을 실행하였다. 그 결과 모든 차종에서 최우수 모델은 CBR 모델로 선정되었으며, 차종별 최우수 모델을 대상으로 Tree SHAP Value의 시각화를 실행하여 특성의 기여도 및 방향성을 확인하였다. 본 연구의 시사점으로 온라인 플랫폼 서비스를 이용하는 매매관계자에게 차종별 중고차 가격 예측 모델을 제안하고 특성의 기여 수준과 방향성을 확인함으로써 이들 간 정보의 비대칭으로 야기된 문제 해결에 지원이 될 것으로 기대한다.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.135-147
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• 2005

As automobile technology advances, a smoother ride with less noise is desired. In order to achieve these purposes, a study on the vibration and noise produced by a moving automobile was carried out and a model for tire vibration characteristics which influence the ride performance was developed. The model was verified through simulations and experiments. The developed model was then applied to a half car model and automobile vibrations were analyzed. The effects of tire design parameters on the automobile vibration energy were investigated. The results from laboratory and field tests confirm the validity of the analytical model. The 17-DOF half-car model was built to analyze automobile vibration. The characteristics of the nonlinear model for a shock absorber were applied to this model. The results from the present 17-DOF half car model incorporating the analytical tire model with tire design parameters, were compared with the 5-DOF half car model where the tire was modeled with linear springs. The results of the 17-DOF model are close to the experimental results. Using the 17-DOF model, the influence of tire design parameter were considered. According to the analysis results, the vibrations at seat/body/wheel were predicted by simulation and experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1275-1280
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• 2004

This paper presents the construction of an active suspension system of a one-wheel car model by using fuzzy reasoning. The car model is approximately described by a nonlinear two degrees freedom system subject to excitation from a road profile, and the active control force is constructed by actuating a pneumatic actuator, and the degradation of the performance due to the delay of the pneumatic actuator is improved by inserting a compensator. The fuzzy control is obtained by single input rule modules fuzzy reasoning, and the excitation from the road profile is estimated by using a disturbance observer. The experimental result shows that the proposed active suspension system much improves the performance in the vibration suppression of the car model.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.638-643
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• 2005

This study is about a semi-active quarter car simulation method including a MR(magneto-rheological) damper. The MR damper was modeled as Spencer model that can capture nonlinear and hysteretic behavior. The parameters of the Spencer model were extracted from a random excitation test and optimum treatment of the test data. Then, a suspension control algorithm based on Sky-hook theory was applied for the quarter car simulation. Also, an experiment was dong using a quarter car simulator to confirm the simulation results with the Spencer MR damper model

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1152-1157
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• 2005

This paper is concerned with the construction of an improved sliding mode control for the active suspension system of a one-wheel car model subject to the excitation from a road profile. The active control is composed of the equivalent and the switching controls where an improved sliding surface is proposed. The active control force is generated by operating a pneumatic actuator due to the control signal that constructed by measuring the state variables of the car model and by estimating the excitation from the road profile using the VSS observer. The experimental result indicates that the proposed active suspension system is relatively effective in the vibration suppression of the car model.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1016-1022
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• 2005

This study is about a semi-active quarter car simulation method including a MR(magneto-rheological) damper. The MR damper was modeled as Spencer model that can capture nonlinear and hysteretic behavior. The parameters of the Spencer model were extracted from a random excitation test and optimum treatment of the test data. Then, a suspension control algorithm based on Sky-hook theory was applied for the quarter car simulation. Also, an experiment was done using a quarter car simulator to confirm the simulation results with the Spencer MR damper model.