• Proceedings of the KSR Conference
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• 2007.11a
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• pp.115-122
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• 2007

The noises which occurs from the rolling stock can be divided largely into three classes and they are Rolling noise, Traction noise and Aerodynamic noise. In the event of braking the rolling stock which enter into the station, Brake shoes cause Fraction noise (braking noise) and excessive braking noise makes passengers and operators uncomfortable. This study is to reduce squeal noise and minimize displeasure by measuring the braking noise and defining the major noise sources and noise mechanism

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1148-1153
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• 2008

Noise pollution from a high speed train has been a serious social issue nowadays. Especially when a train speed exceeds 350 km/hr, an aerodynamic noise level has been known to be increased drastically. In this paper, explained were the studies on the noise reduction and engineering approaches to estimate and analyze influences of noise. Based on this study, it is estimated to apply results to development of trains and expected to accomplish futuristic technology by devising noise prediction of high speed EMU and measures to reduce noise on a design phase.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.273-279
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• 1998

This study represents the technique about the noise reduction of HVAC equipment for high speed train(HST) operating at 200km/h. HST is different from the low speed train in the various points as well as the speed. Especially, the noise of cabin is closely related to the comfort of passenger and the noise from HVAC is one of main noise source in the cabin. In this study, the noise from HVAC was reduced by 5 dB(A) using the concept of multiple resonator and guide vein. Therefore, the noise of cabin decreased from 60 dB(A) to 55 dB(A) at the center of the cabin.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.824-829
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• 2004

In this paper, the process of development of resilient sleepers, which improves the train safety, passenger comfort and reduces the noise and vibration, is presented. To optimize the bonding method between elastic pad and PC sleeper, special pad shape like arrow is adopted and is applied in manufacturing. Bonding strength and reduction effects of vibration of the resilient sleepers are experimentally investigated. From the experiment results, it is investigated that the bonding strenth is enough to satisfaction the criteria and the vibration characteristic is also more effective for sleeper with elastic pad than that in ordinary PC form. These results indicate that the elastic pad can reduce possibility of rail-corrugations and thus resulting in the reduction of maintenance costs.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.241-248
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• 1998

A Systematic approach to estimate an interior noise level for a railway passenger car has been proposed. The prediction is based on the sound power values obtained from measured sound pressure lever, when a high speed train runs at 300km/hr. Then, the exterior sound pressure value is calculated by using the BEM code. After that, an interior sound lever is estimated, considering the transmission loss of body structures and absorption effect inside of the train. In this application, the estimated noise level is between 66 dBA and 74 dBA. The proposed approach could be useful for rough estimation of a noise level inside a passenger car at the design stage, a]though the method has some limitation to be implement for a general situation.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.209-214
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• 2009

In this research, an external noise distribution of a HST has been analyzed by using a ray tracing techniques. An aero-dynamic noise generated from a bogie has been considered as a major noise source. Then a distribution of the noise on the outside of the vehicle is calculated using a ray noise technique. The models simulated are two different acoustic fields: an open field and a tunnel. In order to evaluate the noise effects, an exterior structure has been modified by using a different length of skirts. Various application schemes of reducing an environmental noise level will be expected for a HST based on this research.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.447-453
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• 2009

The interior noise of the High Speed Train(HST) is analyzed by applying the statistical energy analysis (SEA) method. The interior of each vehicle is divided lengthwise into nine cavities. Since the rolling noise and aerodynamics noise are expected to be dominant noise sources, they are treated as the noise sources in the model. To further simplify the model, curtains and seats are excluded. The simulation runs involving one-car, three-car and five-car trains are conducted. The maximum predicted noise level is 98.4dB. The results also show that the predicted noise levels are within 0.23% of each other. The results imply that it is not necessary to estimate the interior noise of the train by constructing multiple-car train models. The noise estimate based on just one-car train can be optimal with respect to the computational effort and modeling time.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1441-1447
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• 2008

This research studies the effects of community noise around railway, noise from the inside/outside noise of the High-Speed EMU. First study part of this year is research of the noise source. The modeling methodology for prediction of noise level including the frequency property, velocity dependence, sound pressure of noise source is investigate. Second part is research on the sound transmission loss. An exclusive program which could analyze the sound transmission loss of the floor, the sides(mirror), insulator in High-Speed EMU has to be developed. Third part is research on the train inside/outside and Prediction for community Noise. In order to predict the noise when the High-Speed EMU is traveling at the outside and along tunnels, the result of the research can be derived by evaluating the effect of the noise on the upper/middle parts of the carriage and on the railroad way round about with using the program.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.717-722
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• 2011

In this paper, noise source localization of the Korean high speed train was conducted by using delay and sum beam-forming method of a microphone array. At first, the microphone array having irregular configuration was designed and the resolution of which was analyzed from parameters such as 3-dB bandwidth and maximum side-lobe level. After the demonstration, the microphone array was applied on the high speed train and noise localization of the high speed train driving at 300 km/h was performed successfully.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1242-1248
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• 2001

In this paper, the process of development of resilient sleepers, which improves the train safety, passenger comport and reduces the noise and vibration, is presented. To determine the required material properties of elastic pad, static and dynamic simulations are performed and is applied in manufacturing. Lateral resistance and durability characteristics of the resilient sleepers are experimentally investigated. From the experiment results, it is investigated that the displacement is less for sleeper with elastic pad than that in ordinary PC form. However, the lateral resistance is investigated little less -for sleeper with elastic pad than ordinary PC form. These results indicate that the elastic pad can reduce possibility of rail-corrugations and thus resulting in the reduction of maintenance costs.