• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.827-832
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• 2013

In this study, curve responsiveness was assessed based on the lateral force and running safety was evaluated based on the wheel unloading ratio and derailment coefficient, which is the ratio of the wheel load and the lateral force. The evaluation of the curving performance and running safety of the new high-power electric locomotive showed that the derailment coefficient appeared higher when the wheel-set was set to the front of the train instead of being placed backward, and the maximum value of the derailment coefficient was recorded as 0.572 on the Gyeongbu line. Furthermore, the lateral force increased in curved sections, and it appeared to be proportional to the curve radius. Meanwhile, a maximum axis lateral force of 77.6 kN was recorded on the Taebaek line, and the wheel unloading ratio was 47.6% on the Yeongdong line. Finally, the running safety at the maximum speed as well as the through-curve performance of the curve radius satisfied the required standards.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.581-587
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• 2013

In a magnetic train set composed of more than two cars, the installation of dampers between cars is carefully considered for improving both the ride quality and the safety, particularly during curve negotiation. In this study, a dynamic simulation of the ride quality and curve negotiation of a Maglev vehicle was carried out. The dynamic model is developed based on multibody dynamics. The presented full vehicle multibody dynamic model integrates the electromagnet model and its control algorithm. By using this model, the effects of the dampers are numerically analyzed. The proposed damper is installed on the vehicle and tested to analyze its effects. In this study, the simulation and measured results of the vehicle behavior and ride quality are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.431-432
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• 2010

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.47-59
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• 2014

This paper deals with a vision-based trajectory tracking control system for a quadrotor-type UAV for entertainment purpose in indoor environment. In contrast to outdoor flights that emphasize the autonomy to complete special missions such as aerial photographs and reconnaissance, indoor flights for entertainment require trajectory following and hovering skills especially in precision and stability of performance. This paper proposes a trajectory tracking control system consisting of a motion generation module, a pose estimation module, and a trajectory tracking module. The motion generation module generates a sequence of motions that are specified by 3-D locations at each sampling time. In the pose estimation module, 3-D position and orientation information of a quadrotor is estimated by recognizing a circular ring pattern installed on the vehicle. The trajectory tracking module controls the 3-D position of a quadrotor in real time using the information from the motion generation module and pose estimation module. The proposed system is tested through several experiments in view of one-point, multi-points, and trajectory tracking control.

• Journal of Korean Society of Transportation
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• v.18 no.6
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• pp.47-61
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• 2000

차량추종모형은 차선변경모형과 함께 미시적 시뮬레이션 모형의 핵심 모형으로서 정확한 차량추종모형의 적용은 시뮬레이션 모형 분석결과의 신뢰성에 영향을 미친다. 기존의 차량추종모형은 대부분 가속상황과 감속상황에 동일한 모형을 적용하거나 자극부문과 민감도 부분은 거의 동일한 형태를 취하고 있으며, 가상자료를 토대로 모형이 개발되었다. 본 연구의 목적은 첫째, 모형을 추정하기 위한 연구체계를 구성하고, 둘째, 이러한 연구체계를 이용하여 신호교차로 미시적 시뮬레이션에 직접 적용이 가능한 차량추종모형을 정립하는 데 있다. 본연구에서는 이를 위해서 신호교차로에서 미시적 실측자료를 수집하였으며, 수집된 자료에서 통계적 기법을 통해서 모형 추정에 적합한 자료를 구축하였다. 현장에서 실측된 이산적인 원시자료는 차량추종모형 추정에 직접 이용할 수 없다. 따라서, 이산적 원시자료를 모형추정에 적합한 자료로 구성하기 위하여 비선형 곡선적합 알고리즘을 이용하여 연속적인 궤적함수를 구성하였고, 이를 통해서 모형추정에 필요한 선두차량과 후행차량의 현재시점과 반응시간 이후 시점에서의 위치, 순간 가속도와 순간속도 등을 도출하였다. 본 연구에서는 차량추종상황을 가속상황, 감속상황, 출발상황, 그리고 정지상황으로 구분하여 차량추종모형을 구축하였다. 가속상황과 감속상황에 대해서는 실측자료를 이용하여 모형을 추정하였으며, 출발상황과 정지상황에 대해서는 추정된 가/감속상황의 모형을 바탕으로 출발상황과 정지상황에서의 차량행태를 설명할 수 있는 모형을 구축하였다 또한, 민감도와 자극부분을 새롭게 정의하여 각 상황별로 미시적 실측자료를 이용하여 모형을 추정하였다. 이렇게 추정된 모형들 중에서 통계적 기법과 실측치와의 비교를 통해서 가장 적합한 모형을 선택하였다. 선택된 모형은 통계적 검정, 가상자료 그리고 실측치와의 비교를 통해서 분석하였으며, 분석결과 구축모형의 적용성은 우수한 것으로 분석되었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.179-188
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• 1990

The characteristic of volumetric efficiency considering gas exchange process in a reciprocating engine is presented in this paper. The characteristic method is used for solving gas exchange problems of engine system in theoretical studies. The validity of the simulation is investigated by a comparison with the results obtained by the experiment which have been performed on the practical 4-cycle, 4-cylinder gasoline engine. The relationship between the volumetric efficiency and the intake pressure variation according to configuration of intake pipe, position of branch point, valve timing, compression ratio is clarified through simulation and experiment. The results predicted by the simulation are found to be in approximate agreement with those obtained by the experiment.

• Journal of Korean Society of Transportation
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• v.24 no.5 s.91
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• pp.35-44
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• 2006

Acceleration and deceleration curves have been used for design purposes worldwide. The curve in design level has been regarded as an single deterministic curve to be used for design of climb lanes. It should be noted that the curve was originally made using ideal driving truck and that the curve is applied during design based on the assumption of no difference between ideal and real driving conditions. However. observations show that aged vehicles and lazy behavioring drivers nay make lower performance of vehicles than the ideal performance. The present paper provides the results of truck speeds at climbing lanes then probabilistic variation of acceleration and deceleration corves. For these purposes. a study about identification of vehicle makers, and weights for trucks at freeway toll gates and then observation of vehicle-following speed were performed. The 85%ile results obtained were compared with the deterministic performance curves of 180, 200, and 220 Ib/hp. It was identified that the performance of 85%ile results obtained from vehicle-following-speed observations were lower than one from deterministic performance curves. From these results, it may be concluded that at the beginning Point of climbing lanes additional $16.19{\sim}67.94m$ is necessary and that at the end point of climbing lanes $53.12{\sim}103.24m$ of extension is necessary.

• Journal of the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.257-263
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• 2007

The critical speed above which the vehicle become unstable is one of the items that should be verified in the development of a new train. In the case of a high speed tilting train, which requires both higher critical speed and higher curving speed, the critical speed should be more carefully treated because the both requirements are in conflict with each other in the conventional train design. The main purpose of the present work is to estimate the linear and non-linear critical speeds of 200km/h Korean Tilting Train 'Hanbit200' under development. The newly developed self-steering mechanism was attached to the tilting train to ensure that the critical speed falls under the lower yaw stiffness which is needed to secure higher curving performance. The simulation for predicting the critical speed was done by a commercially available vehicle dynamics software. A full scale roller rig test was carried out to validate the numerical results and to verify the effectiveness of the self-steering mechanism.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.599-605
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• 2017

For an unmanned vehicle to be driven on the off-road terrain, it is necessary to consider the vehicle's stability. This paper suggests a path tracking controller for simulation of real-time vehicle stability analysis. The path tracking controller uses the preview distance to track the given trajectory. The disturbance moment is estimated using the yaw moment observer, and this information is used for compensation in the yaw moment control. On a curved path, the vehicle's desired velocity is determined from the curvature of the path. Because the vehicle is equipped with six independent motor driven wheels, the driving torques are distributed on all the wheels. The effectiveness of the path tracking controller is verified using ADAMS/MATLAB co-simulation.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.745-750
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• 2004

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 80km/h for estimating the curving performance and running safety of Gwangju EMU. As the test results, could confirm the curving performance and running safety of Gwangju EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.