Joon-Hyuk Park

A Study on Relationship between Curving Noise and Wheel Wear in Seoul Subway System

There are many curves in Seoul subway system. Therefore, the noise from subway system in curved line gives displeasure to passenger. The subway noise in curved line is affected not only by rail condition but also wheel condition and dynamic characteristics. The railway curving noise can be divided into 2 categories. The first is the noise due to stick-slip between wheel tread and rail head, and the second is one by wheel flange contact on rail side. Because of these phenomena - stick-slip and wheel flange contact - wheels are worn seriously. In this study the curving noise was reviewed by using eigen-mode of wheel and waterfall plot which shows noise level in time-frequency domain. And also those were reviewed in viewpoint of stick-slip noise and wheel flange contact noise. Finally, the relationship between curving noise and wheel wear was studied.

Active steering control of railway vehicles using linear quadratic Gaussian (LQG)

In urban transit systems, railway vehicles are often required to negotiate tight curves. During curve negotiation, the wheelsets of conventional vehicles generally misalign radically with the track increasing wheel/rail contact forces and resulting in increased wheel and rail wear, outbreak of squeal noise, fuel consumption, and risk of derailment. This paper presents active steering controller design in the railway systems using Linear Quadratic Gaussian. Simulation results have been shown that the proposed LQG method methodology robustly yields uniform performance with adequate response over the axle weight and wheel conicity variation range.

Development of brake system of railway vehicles for real-time HILS

Brake system of railway vehicles has a crucial role for the safety as well as riding quality of passengers. Its core technology for successful development of the brake system is to design of ECU (Electric Control Unit) containing antiskid control, brake blending control, load compensating control, and so on. Each development procedure of ECU involves a verifying test for each step and is completed by an evaluation test of the comprehensive performance verification for the overall systems. The development tool which is applied to this objective is the HILS (Hardware-In-the- Loop-Simulation). In order to design a controller, a good representative model of the system is needed. This paper describes the dynamic modeling of brake system of railway vehicle for HILS and analyzes some dynamic behavior under emergency braking force.

Acoustical device using helmholtz resonator for the high-speed train noise barrier

This study is primarily aimed at developing a measure to overcome the limited shielding performance of the noise barriers for the high-speed train. Up to the train speed of 300km/h and more the noise incidence angle and the source height change due to the pronounced aerodynamic noise source parts located at the higher positions compared to the height of the conventional rolling noise source. By means of the experimental analysis on the sound radiation characteristics and the sound pressure distribution around the noise barrier, a prototype of an acoustical attachment is porduced based on the analytical model calculation and numerical analysis. The principle of the Helmholtz resonator is used to optimize the acoustical impedance on the surface of the upper dege of the noise barrier. Using the model it was possible to find an appropriate acoustical property for the impedance according to the target frequency,sound incidence angle relative to the barrier and the receiver position. In this paper the results o...