• Proceedings of the KSR Conference
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• 2006.11b
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• pp.454-459
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• 2006

A wheel force becomes large as increasing the stiffness of rail-pad, and it accelerates the deterioration of track, and it leads the maintenance cost rising. So, it is required to determine an appropriate replacement period for rail-pad. As a preliminary study to determine it, a numerical analysis was conducted to investigate the influence on a track behavior by the hardening of rail-pad. From the analysis, one knows that the dynamic wheel force is vary depend on the stiffness of rail-pad and the running speed of vehicle, the displacement and acceleration of rail is decreasing as increasing stiffness of rail-pad, and the displacement and acceleration increased in proportion to the rail-pad stiffness increasing.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.141-148
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• 2008

In this paper, we develop a detailed full dynamic model which includes various rough terrains for 6-wheel skid-steering mobile robot based on the real experimental autonomous vehicle called Dog-Horse Robot. We also design a co-simulation for performance comparison of path tracking algorithms. The control architecture in the co-simulation can be divided into two levels. The high level control is the closed-loop control of path tracking to follow a given path, and the low level is concerned about torque control of wheel motion. The simulation using the mechanical data of the Dog-Horse Robot is performed under the Matlab/Simulink environment. We also simulate and evaluate the performance of the model based adaptive controller.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.71-78
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• 2011

A kart is a vehicle without the suspension system and the differential gear. The kart frame as an elastic body plays the role of a spring. By the cornering of a kart, rolling, pitching and twisting motions are induced in the kart frame. Also the slip or noncontact of the wheel and a permanent deformation of the kart frame can be induced. In order to examine closely this phenomenon, measurement on height-displacements with various sensors and tracking system and analysis on the kart frame twisting characteristics with the rolling and pitching angle are needed. According to the measurement result, while driving in a curve at high speed the kart frame is quite twisted. Analysis on the measurement results shows that a kart used primarily in high speed requires a frame with low torsional stiffness and a frame material with high tensile strength and large elongation.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.421-428
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• 1998

Sensitivity analysis of suspension elements of an articulated bogie for light railway vehicles is presented. The ride, stability and safety are used as dynamic performance index. Suspension elements of 10 and a conicity of wheel are used as design variables, To analyze sensitivity of design variables, the railway vehicle dynamics analysis program AGEM is used. The results shows that the secondary suspension elements have a strong effect on ride and the primary suspension elements have a moderate effect on ride. Conicity of wheel has a strong effect on the stability, The safety is not effected by all the design variables.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.595-600
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• 2009

Passengers in a vehicle feel uncomfortable due to squeal noise. Squeal noise, a kind of self-excited vibration, is generated by the friction force between the disc and the pad of the automobile. In this paper, modal analysis of wheel brake system was performed in order to prediction of squeal phenomenon. It was shown that the prediction of system instability is possible by FEM. Finite element model of that brake system was made. Some parts of a real brake was selected and modeled. The normal mode analysis method performs analyses of each brake system component. Experiment of modal analysis was performed for each brake components and experimental results were compared with analytical result from FEM. The complex eigenvalue analysis results compared with braking test. The analysis results show good correlation with braking test for the squeal frequency at an unstable mode.

• Journal of the Korean Society of Safety
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• v.38 no.4
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• pp.1-7
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• 2023

The steel wheels of urban railway vehicles gather a lot of data through regular measurements during maintenance. However, limited research has been carried out utilizing this data, resulting in difficulties predicting the maintenance period. This paper studied a machine learning model suitable for mileage prediction by studying the characteristics of mileage change according to diameter and flange thickness changes. The results of this study indicate that the larger the diameter, the longer the travel distance, and the longest flange thickness is at 30 mm, which gradually shortened at other times. As a result of research on the machine learning prediction model, it was confirmed that the random forest model is the optimal model with a high coefficient of determination and a low root mean square error.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.81-90
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• 1995

Anti-lock Brake System has been developed to reduce tendency for wheel lock and improve vehicle control during sudden braking on slippery road surfaces. This is achieved by controlling the braking pressure avoiding wheel lock, while retaining handling and brake performance. This paper is concerned about characteristics of a solenoid valve in hydraulic modulator for controlling brake pressure. First, it was modeling the electromagnet by the permeance method. Second, it was modeling the commercial Maxwell poackage program. And then, a experiment was performed in order to justify modeling. The result of modeling coincided with teh result of experiment and commercial packabe program. As a result, these modelings will be able to use in analysis of dynamic character- istics of the solenoid valve for braking.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.271-272
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• 2024

현재 자동차 산업은 내연기관에서 전기차 시스템으로 접어들고 있다. 전 세계적으로 탄소 중립 정책이 이를 가속화하고 있으며, 자동차 제조사들은 기존 내연기관 시스템으로는 불가능했던 기술들을 개발하고 있다. 대부분의 전기차에는 PMSM이 적용되고 있는데 부피가 크고 무거우며 토크 밀도가 낮다는 단점이 있다. AFPM은 기존 PMSM의 단점을 개선한 모터로, 부피와 무게가 작으며 토크밀도가 높다는 장점이 있어 전기차의 In-Wheel Motor System과 UAM에 적용되는 모터이다. 하지만 전기차는 도로 주행만 가능하고 UAM은 비행만 할 수 있기 때문에, 미래 모빌리티인 전기자동차와 UAM이 통합된 모빌리티를 개발하고자 한다. 본 과제에 적용되는 AFPM모터는 PMSM의 단점을 보완할 수 있기 때문에 전기차-UAM 트랜스포밍 모빌리티의 모터로 적합하다. 이 모빌리티는 자동차와 UAM의 역할을 모두 수행할 수 있어 효율적인 이동을 돕고 도시의 교통 인프라 문제를 완화할 수 있다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.208-214
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• 2014

Vehicle dynamic states used in various advanced driving safety systems are influenced by road geometry. Among the road geometry information, the vehicle pitch angle influenced by road slope and acceleration-deceleration is essential parameter used in pose estimation including the navigation system, advanced adaptive cruise control and others on sag road. Although the road slope data is essential parameter, the method measuring the parameter is not commercialized. The digital map including the road geometry data and high-precision DGPS system such as DGPS(Differential Global Positioning System) based RTK(Real-Time Kinematics) are used unusually. In this paper, low-cost cascade extended Kalman filter(CEKF) based road slope estimation method is proposed. It use cascade two EKFs. The EKFs use several measured vehicle states such as yaw rate, longitudinal acceleration, lateral acceleration and wheel speed of the rear tires and 3 D.O.F(Degree Of Freedom) vehicle dynamics model. The performance of proposed estimation algorithm is evaluated by simulation based on Carsim dynamics tool and T-car based experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.170-177
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• 2020

This study examined the clamping force control method and the braking performance test results of an electromechanical brake (EMB) using braking test equipment. Most of the studies related to EMBs have been carried out in the automotive field, dealing mainly with the static test results for various control methods. On the other hand, this study performed a dynamic performance evaluation. The three-phase interior permanent magnet synchronous motor (IPMSM) was applied to drive the actuator of the EMB, and the analysis was verified by JMAG(Ver. 18.0), which is finite element method (FEM) software. The current control, speed control, and position control were used for clamping force control of the EMB, and the maximum torque per ampere (MTPA) control was applied to the current controller for efficient control. The EMB's emergency braking deceleration performance was tested in the same way as conventional pneumatic brake systems when the wheel of a train rotates at 110 km/h, 230 km/h, and 300 km/h. The emergency braking time, with the wheel stopped completely at the maximum rotational speed, was approximately 73 seconds. The similarity of the braking time and deceleration pattern was verified through a comparison with the performance test results of the pneumatic brake system applied to the next generation high-speed railway vehicle (HEMU-430X).