• Proceedings of the KSR Conference
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• 2011.10a
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• pp.670-677
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• 2011

In this research, noise of the Korean high-speed train running at different speed from 150 to 300 km/h was measured by using microphones and the difference of sound pressure according to its driving velocities was analyzed. In addition, sound pressure characteristics of front, pantograph, bogies and between-car sections of the Korean high-speed trains were deduced by applying delay and sum beam-forming method using a microphone array. From the research, the effects of locations of the high-speed train were investigated. The results of this research can be utilized to reduce noise of a high-speed train.

• Proceedings of the KSR Conference
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• 2003.10a
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• pp.3-16
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• 2003

'High speed' in today's railway is generally understood to mean 'regular revenue-earning operation of passenger trains at more than 200 km/h', and true high-speed services in this sense began in Japan in 1964. Today, Japan's high-speed rail network slightly exceeds 2, 000 km, carrying around 750, 000 passengers every day without any fatal accident for nearly 40 years.(omitted)

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.61-68
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• 2024

The majority of high-speed railway bridges along the domestic Gyeongbu and Honam lines feature a PSC-box type structure with a span length ranging from 35 to 40m, which typically exhibits a first bending natural frequency of approximately 4 to 5Hz. When KTX high-speed trains transverse these bridges at speeds ranging from 290 to 310km/h, the vibration induced by the trains approaches the first bending natural frequency of the bridge. Furthermore, with the upcoming operation of a EMU-320 high-speed train and the anticipated increase in the speeds of these high-speed trains, there is a need to analyze the dynamic response of high-speed railway bridges. For this, based on measured responses from actual railway bridges, a numerical model was constructed using a numerical model updating technique. The dynamic response of the updated numerical model exhibited a strong agreement with the measured response from the actual railway bridges. Subsequently, this updated model was utilized to analyze the dynamic response characteristics of the bridges when KTX and EMU-320 trains operate at increased speeds. The maximum vertical displacement and acceleration at the mid-span of the bridges were also compared to those specified in the railway design standard with the increasing speed of KTX and EMU-320.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.244-252
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• 2012

Recently, the speed of a train has been increased. So the trains are being exposed to wind more severely than before. Because of the operation of high speed trains and lightweight of the train, risks of train derailment have being increased. In this study, aerodynamic effects of a newly designed high speed train, HEMU-400x, are evaluated. For aerodynamic effect evaluation, analysis method is selected by examining the safety standards for high speed train. The condition of aerodynamic effects is selected by adverse effect conditions. In order to calculate $C_s$ coefficients, numerical analysis is conducted. Using $C_s$ coefficients, the side force is calculated. Through dynamics analysis, derailment and wheel unloading are obtained. Using these results, derailment evaluation is performed.

• Structural Engineering and Mechanics
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• v.59 no.2
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• pp.277-290
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• 2016

This paper investigates the ground vibration induced by high-speed trains moving on multi-span continuous bridges. The dynamic impact factor of multi-span continuous bridges under trainloads was first determined in the parametric study, which shows that the dynamic impact factor will be large when the first bridge vertical natural frequency is equal to the trainload dominant frequencies, nV/D, where n is a positive integer, V is the train speed, and D is the train carriage interval. In addition, more continuous spans will produce smaller dynamic impact factors at this resonance condition. Based on the results of three-dimensional finite element analyses using the soil-structure interaction for realistic high-speed railway bridges, we suggest that the bridge span be set at 1.4 to 1.5 times the carriage interval for simply supported bridges. If not, the use of four or more-than-four-span continuous bridges is suggested to reduce the train-induced vibration. This study also indicates that the vibration in the train is major generated from the rail irregularities and that from the bridge deformation is not dominant.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.611-616
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• 2003

The application of the tilting train is one of the most efficient ways to increase curving speed of train on existing tracks or on mountain railway lines with sharp curves. It can increase the running speed and ensure the passenger comfort and safety at the same time. Therefore, the development of tilting train has been paid high attention by many countries in the world. Tilting trains have been operated successfully in many countries such as Italy, Spain, Germany, Sweden, England and so on. The tilting trains possess broad prospects in raising speeds. The distributed EMU tilting train set will be developed according to the Korea railway conditions and will be operated on the Honam line, Janghang line and Jungang line. Because there is high percentage of curves on these lines. these lines are suited to operating tilting trains to raising speed and saving passenger traveling time. In order. to improve the curving performance of the tilling train. the active-control algorithm is utilized for the tilting bogie.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.193-196
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• 2014

Experimantal evaluation of an energy storage device with high rotational speed to store regenerative energy which might be generated during the braking period of the trains is presented. The proposed ESS is small scale model and has 5kW output power, high rotational speed. In general railway trains generate regenerative energy for 10-20 sec when the train brakes and also high traction energy is needed for very short moment (10 sec) when the train increases the traction force. Considering such characteristics of the railway system energy storage device for the railway should have very fast response property. Among the various energy storage devices flywheel energy storage system has the fastest response property, which means that flywheel ESS is the most suitable for the railway system.

• Wind and Structures
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• v.35 no.3
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• pp.177-191
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• 2022

Trains emerging on a streamlined bridge-girder may have salient interference effects on the aerodynamic properties of the bridge. The present paper aims at investigating these interferences by wind tunnel measurements, covering surface pressure distributions, near wake profiles, and flow visualizations. Experimental results show that the above interferences can be categorized into two primary effects, i.e., an additional angle of attack (AoA) and an enhancement in flow separation. The additional AoA effect is demonstrated by the upward-moved stagnation point of the oncoming flow, the up-shifted global symmetrical axis of flow around the bridge-girder, and the clockwise-deflected orientation of flow approaching the bridge-girder. Due to this additional AoA effect, the two critical AoAs, where flow around the bridge-girder transits from trailing-edge vortex shedding (TEVS) to impinging leading-edge vortices (ILEV) and from ILEV to leading-edge vortex shedding (LEVS) of the bridge-girder are increased by 4° with respect to the same bridge-girder without trains. On the other hand, the underlying flow physics of the enhancement in flow separation is the large-scale vortices shedding from trains instead of TEVS, ILEV, and LEVS governed the upper half bridge-girder without trains in different ranges of AoA. Because of this enhancement, the mean lift and moment force coefficients, all the three fluctuating force coefficients (drag, lift, and moment), and the aerodynamic span-wise correlation of the bridge-girder are more significant than those without trains.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.425-431
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• 2013

Nowadays, high speed train has settled down as a fast and convenient environment-friendly transportation and it's need is gradually increasing. However increased train speed leads to increased aerodynamic noise, which causes critically affects comfortability of passengers. Especially, the pantograph of high speed train is protruded out of train body, which is the main factor for increased aerodynamic noise. Since aerodynamic noise caused pantograph should be measured in high speed, it is difficult to measure it and to analysis aerodynamic noise characteristics due to the various types of pantograph. In this research, aerodynamic noise of pantograph is predicted by CFD (Computational Fluid Dynamic) and FW-H (Ffowcs Williams-Hawkings) equation. Also, Wind tunnel test results and numerical simulation results were compared. As a result, Simulation results predicting sound pressure level is very similar with wind tunnel test result. To analyze contribution of the pantograph to the noise of high-speed train, simulation results compared with measurement results of exterior noise. The simulation reuslts found that pantograph is a dominant noise source of high-speed trains's exterior noise in low frequency section. This dominant noise was come out from vortex shedding of the panhead in the pantograph. This research will be utilized for reduce sound pressure level of pantograph.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.337-344
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• 1998

Conceptual design of the pantograph for high speed trains of 350km/h is introduced. The aims to be accomplished in the concept design are the good dynamic performance, low noise, aero-dynamic stability. The resulting mechanism of the pantograph have single-arm type structure with bebel gears to reduce noise sources, symmetric structure for the aero-dynamic stability and the special panhead assembly to obtain good dynamic performances.