• Journal of the Korean Society for Railway
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• v.4 no.4
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• pp.123-130
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• 2001

A chevron rubber spring is used in primary suspension system for rail vehicle. The chevron spring support the load carried and reduces vibration and noise in operation of rail vehicle. The computer simulation using the nonlinear finite element analysis program MARC executed to predict and evaluate the load capacity and stiffness for the chevron spring. The appropriate shape and the material properties are proposed to adjust the required characteristics of chevron spring in the three modes of flexibility. Also, several samples of chevron spring are manufactured and experimented. It is shown that the predicted values agree well the results obtained from experiment.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2115-2124
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• 2011

The rail surface defects which are generated on repeated rolling contact fatigue are getting increased according to high speed, high density, and minimum weight. In addition, Increasing noise and vibration are affected by these also impact load generated as well. Because of this phenomenon, more serious and critical damages were occurred. In fact, in order to control them, the rail grinding were conducted. However, there are not enough researches to make an criteria of generating optimal rail grinding amount in Korea. This study evaluated how depth of hardening on rail surface is formed and suggested optimal rail grinding amount by RCF(rolling contact fatigue) test with generated contact pressure between KTX wheel and UIC60 rail by applying FEM analysis. Therefore, the amount was generated approximately 0.2mm/20MGT to maintain integrity of rail surface by getting rid of depth of hardening on rail according to rail accumulated passing tonnage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.615-621
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• 2015

In this paper diamond wire cutting method has been proposed to cut the rock in the tunnel face. Diamond wire saw method could cut the rock from tunnel face with very minor vibration and noise. In this study rock cutting process has been simulated with FEM method by using LS-DYNA explicit non-linear finite element code. Normal load act as an prime factor when cutting the rock surface. For observing the effect of normal load on bead, several experiments has been conducted by varying normal loads on the bead. From each experiment, cutting rate has been calculated to compare the cutting rate with different load conditions. By increasing the normal load on bead, cutting rate increases drastically.

• Journal of the Korean Society for Railway
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• v.4 no.1
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• pp.16-22
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• 2001

This paper describes two different systems which can compensate harmonic currents generated in the power system. As non-linear loads increase gradually in industry fields, harmonic current generated in the electric power network system also increases. Harmonic current makes a power network current distorted and generates heat, vibration, noise in the power machinery. Many approaches have been applied to compensate harmonic currents generated in the power network system. Among various approaches, in this paper, two kinds of approaches are compared and evaluated. They are flywheel compensator based on secondary excitation of wounded rotor induction motor(WRIM) and primary excitation of squirrel cage induction motor(SCIM). Both systems have a common structure. They use a flywheel as a energy storage device and use PWM inverters.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1276-1281
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• 2006

In general, the wheel-skid prevention of braking system is very important in modern railway applications. This is because wheel-skid can lead to an increase in noise and vibration from wheels with flat points, as well as an increased braking distance. However conventional anti-skid control has problems because wheel adhension and skid characteristics are very difficult nonlinear systems and time consuming to accurately model. In this paper, we design a fuzzy controller using a model of relation between ahdension and braking force, we show that anti-skid fuzzy controller has a very good performance, performing better than the previous conventional controller.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.778-782
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• 2004

Floating floor structure, which is mainly adopted for reducing interior noise of railway vehicle, is known that it is superior to single wall in respect of sound transmission loss. The dynamic characteristic of the support in the floating floor that is one of the important design variables in floating floor structure can change the sound and vibration insulation properties of it. From excitation test, the dynamic stiffness and loss factor of the support are evaluated. They are used as input parameter for analyzing the sound transmission loss of floating floor. Predicted transmission loss is compared with the prototype-car test results.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.309-317
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• 2018

Sudden pressure changes caused by the high-speed train entering the entrance of the tunnel are propagated into the tunnel and spread out around the tunnel in the form of a micro pressure wave at the exit of the tunnel. This phenomenon can cause noise and vibration around the tunnel, causing damage to the surroundings. Analysis of this phenomenon is very difficult, but the development of analytical technology has revealed more phenomena than in the past. In this study, we propose this method of analysis and compare it with the experimental data to show the data with higher reliability.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.233-236
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• 2023

본 논문에서는 주거지역에서 철도 운행으로 발생하는 소음, 진동, 미세먼지가 거주민들에게 입히는 피해를 최소화 하기 위해 소음, 진동, 미세먼지의 수치 위험도 기준을 정하고, 아두이노 센서와 모듈로 스마트 창문 및 공기 청정기를 제작한다. 센서를 통해 수집한 데이터가 기준치를 초과할 경우 창문의 개폐 또는 공기 청정기 시스템이 작동을 하도록 구현하여 소음, 진동, 미세먼지 피해를 최소화 하도록 구현하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.10
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• pp.999-1006
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• 2004

Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The railway has the track irregularities which cause vibrations, such as rail joints, turnout, level crossing, transition corves and super-elevation ramps, and variations in the track level(z-axis) and the gauge(y-axis). In Korea, the service run of the high speed train has been made since the 1st of April, 2004. The commercial high-speed trains must be run on the compound lines which are composed of high-speed line and conventional line. The high speed lines in both Kyoungbu line and Honam line have 57.5％ and 33.8％, respectively In this Paper, the ride comfort has been reviewed by the various experimental methods when the high-speed trains are operated on both Kyoungbu line and Honam line. The results show that the high-speed train has no problems from the viewpoint of the comfort ride during the operation on the high speed line and conventional line.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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• pp.1010-1019
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• 2012

Non-contact detection of internal defects in a rail using ultrasonic waves is discussed in this paper. Cracks in a rail may be the cause of a serious railway accident such as derailment if left undetected. Concurrent rail inspection method based on ultrasonic testing using piezoelectric transducers has several limitations as it should keep physical contact with the rail. This work suggests a non-contact detection of internal defects in a rail using ElectroMagnetic Acoustic Transducers (EMAT) which can produce and measure ultrasonic waves in a rail without any couplant. The EMATs for rail inspection are designed and fabricated and their working performance is verified through a series of experiments on various types of internal defects in test rails. The effect of lift-off between the transducers and the rail on the generated signals is also discussed.