• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.95-102
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• 2024

Due to technological advances, the cruising speed of high-speed trains is increasing, and aerodynamic noise generated from the flow outside the train has been an important consideration in the design stage. To accurately predict the flow-induced noise, high-resolution generation of sound sources in the near field and low-dissipation of sound propagation in the far field are required. This should be accompanied by a numerical grid and time resolution that can properly consider both temporal and spatial scales for each component of the real high-speed train. To overcome these challenges, this research simultaneously calculates the external flow and acoustic fields of five high-speed train cars of real-scale and at operational running speeds using a threedimensional unsteady Large Eddy Simulation technique. To verify the numerical analysis, the measurements of the wall pressure fluctuation and numerical results are compared. The Ffowcs Williams and Hawking equation is used to predict the acoustic power radiated from the high-speed train. This research is expected to contribute to noise reduction based on the analysis of the aerodynamic noise generation mechanism of high-speed trains.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.313-336
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• 2007

Unlike a conventional railway system, a high-speed rail system experiences various aerodynamic problems in tunnel sections. Trains running at a high speed in a small tunnel, when compared with the open field, face significant air pressure, resulting in reduced operating stability and fast change in pressure inside the tunnel. These phenomena further cause some unexpected problems such as the passengers onboard feeling an aural discomfort and an impulsive noise at the tunnel exit. To solve these problems, this paper introduces analysis of aerodynamic characteristics for determination of tunnel cross section. The optimum cross-section that satisfies the criteria of aural discomfort was reviewed through lots of numerical simulation analysis. Also, the pressure inside the passenger car of a train operating on Kyungbu HSR line was measured, and the pressure inside the tunnel and the micro-pressure waves at tunnel exit were measured at Hwashin 5 Tunnel. At the same time, a test of train operation model was performed and then the measurement results and test results were compared to verify that various parameters used as input conditions for the numerical simulations were appropriate.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.295-296
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• 2010

본 논문에서는 고속전철용 추진제어장치의 개발 및 본선 주행시험에 관한 내용을 소개하였다. 고속열차용 추진제어장치는 입력 전류의 고조파를 감소하기 위하여 단상 PWM 컨버터 2대가 병렬로 구성되고 인버터는 3상 인버터 1대로 구성된다. 추진제어장치의 전력회로를 간단히 구성하기 위하여 최대용량(4500V/4200A)의 IGBT 전력소자를 적용하였다. 3상 인버터는 가속시 스위칭 기어현상을 저감하기 위하여 저주파 동기 PWM 기법을 적용하였다. 추진제어장치의 성능을 평가하기 위하여 실제 차량이 운행될 본선에서 속도 300km/h까지 가속시험, 비상제동 시험, 구배기동 시험 등을 실시하였다. 시험을 통하여 제작된 추진제어장치가 성능사양을 만족함을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.681-687
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• 2017

We investigated the potential for wind-power generation using the wind produced by express trains. We built equipment to detect the wind velocity, including wind meters and a data analyzer. We considered various conditions that might change the wind. First, we measured the velocity and duration of the wind at three locations distinguished by the presence of a tunnel and a valley landscape. We analyzed the changes in the wind according to the geometric conditions. Also, we analyzed the changes in the wind according to three different heights relative to the train. We also compared the wind produced by a KTX train and an SRT train. Finally, we used the results to derive the wind power energy harvested from the wind and discuss the expected utility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.797-803
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• 2019

This study was carried out to reduce the lateral vibration of high-speed electric multiple units. In the study, the high-speed electric multiple unit prototype (HEMU-430X) has a high lateral vibration at low equivalent conicity regardless of the wheel profiles (XP55, GV40, S1002). As wheel wear progresses and the equivalent conicity increases, the lateral vibration tends to decrease. The reason is that a combination of the suspension characteristics causes the body and bogie to resonate at a frequency of 1.4 Hz when the equivalent conicity is low, resulting in body hunting. An investigation of the lateral vibration of overseas high-speed trains showed that a decrease in the hydraulic stiffness of the yaw damper could improve the vibration. The series stiffness of the yaw damper is a combination of the hydraulic stiffness and elastic joint. In this study, an attempt was made to improve the lateral vibration by lowering the stiffness of the elastic joint. The series stiffness of the adjusted yaw damper was approximately 60% compared to the original one. The on track test results showed improvement in the lateral vibration for both running directions. The vibration reduction method of this study can be used for EMU-250 and EMU-320 in future commercial operations.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.1-8
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• 2009

Recently, the vibration of underground structure due to high speed railway loads has been increased substantially as compared with middle and slow speed. The buried gas pipelines under continuous impact forces and repeated loading are more influenced by the vibrational loads than another pipelines. However, the static analysis was not enough to allow for the effect of vibrations because it uses impact factors for the design or analysis process. In this study, characteristics of Pipelines was quantitatively estimated through each conditions of soil covers and train speed, and the new vibration prediction is presented about the vibrational velocity.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.343-351
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• 2012

With the cooperation of many research institutes and railway companies, the next generation high speed train is under development for many years. To confirm the safety requirement of the developed high speed train, multibody dynamic analysis is implemented. Through this analysis, railway derailment and lateral guiding force simulation was evaluated according to UIC code 518 OR for international railway vehicle. Test results were compared by limit value of safety criteria. Safety evaluation results, according to international standards, would provide basic reference data of ensuring safety speed and track radius curve. The safety of the train at the maximum speed is verified by numerical analysis results.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.409-416
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• 2016

The contact force characteristic between the pantograph and the catenary wire represents the current collection quality of trains; it should be precisely controlled under international standard. Recently, a noise reduction cover has been installed around the pantograph of high speed trains. However, little study on the contact force by the pantograph cover has been conducted. In this study, the impact on the current collection performance of the pantograph cover was analyzed by dynamic contact force measurement using a next generation high speed train (HEMU-430X). As a result, it was confirmed that the attachment of a pantograph cover could lower the mean contact force by approximately 50N at 300km/h. In addition, the pure difference of the average contact force by the presence of pantograph cover, except for the static pressure, was measured and found to be up to 110N at 300km/h. It was also found that the standard deviation of the contact force of 3~5N could be changed by use of a pantograph cover.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.304-313
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• 2016

It is necessary to receive telegrams transmitted by transponder tags installed along the track in order to detect the exact position of a high-speed train. In a high-speed railway environment, telegrams can be corrupted by the electromagnetic interference that comes from onboard electric train power equipment or wayside devices. In this study, we verified the railway environment compatibility of a high-speed transponder system developed as a train position detection system. We installed transponder tags on the Honam high-speed line and measured the number of error-free telegrams received from the transponder tag while the HEMU-430X was running at 268km/h~334km/h. Based on the measurement, we estimated the length of the contact zone formed between the transponder reader and tag. Field test results allow us to estimate how many error-free telegrams can be received when HEMU-430X is at speeds up to 400km/h.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.987-988
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• 2012