• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1037-1042
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• 2007

KTX trains show a high interior noise level in tunnel with concreted track at 300 km/h. Generally, the concreted track has higher sound emissions compared with ballasted track due to the reduced absorption and the major sources of interior noise for KTX are known as the aerodynamic noise and rolling noise. Therefore, It is necessary to find out noise source and noise components to affect interior noise in tunnel with concreted track. In this study, we measure the noise and vibration inside KTX in tunnel in order to find the cause of the interior noise of KTX. The analysis results show that the interior noise of KTX in tunnel with concreted track is increased sharply by a low frequency below 80 Hz. We know that the low frequency noise inside KTX in tunnel with concreted track is generated at the natural frequency of carbody by aerodynamic noise outside gangway and rolling noise. In order to reduce the noise level at 80 Hz, modification of mud-flap length between carbodys is suggested and the effect of noise reduction is examined in tunnel with concreted track.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.25-28
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• 2005

The interior noise of KTX in tunnel is becoming the problem since the commercial operating in April 2004. The major sources of interior noise for High speed train ate known as the aerodynamic noise and rolling noise generally. We measure the noise and vibration inside KTX in tunnel in order to find the cause of the interior noise of KTX. The analysis results show that the interior noise of KTX in tunnel with concrete track is increased sharply by a low frequency below 80Hz that is the natural frequency of the KTX carbody. We know that the booming noise inside KTX in tunnel with concrete track is generated by aerodynamic noise outside ganqway and rolling noise at the carbody natural frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.340-345
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• 2002

Passengers in automobile or train are exposed to a worse noise environment when they are in the tunnel than in the open field. This is due to a relatively higher space density of sound energy by multiple reflection phenomenon of noise generated by operation of transportation vehicles from tunnel wall compared to open field. In this study, noise characteristics of subway train running through a tunnel were investigated at straight/curved track and tunnel type(semi circular/box). Also the noise measured simultaneously at inner and outer sides of train running through a tunnel, so that the coherence of the various noise sources of subway train to inner noise was evaluated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.749-754
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• 2003

In this paper, we introduce the measurement of the underwater noise with 32channel hydrophone array of Samsung CAvitation Tunnel (SCAT) and the detection technique of noise sources by using the beam-forming method. Measurement and way signal Processing under fluid flow are essential works for the underwater acoustics, especially for the detection of noise sources. As the acoustic impedance of the water is relatively high and the tunnel is an enclosed system, we have to consider the interaction between tunnel and water together with the reflection of noise in the beam-forming technique. Also, for a hydrophone array system that is fixed on one side of tunnel wall as done in SCAT is liable to suffer from some limitations in the detection of the noise sources with the array, we discuss these limitations particularly on the frequency range and spacing of noise sources.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.487-490
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• 2014

These Days a lot of Noise Complaints in vicinity of Railway has been more increase than before. Almost 1/3 Residences who lives in Railway side are Exposure to Noise Pollution. Since the Apartment Buildings around Railway are getting more higher, so those of the Noise Barrier are not best solution anymore. We are going to make a New Plane with the state of the art technology for Railway Noise Abatement Control. Our Goal are focus on a development of Light Weight Noise Tunnel designed by new absorption mat'l and tunnel Stucture on the Overbridge and Viaduct of existing Railway. New Noise Tunnel will be reducing their weight more than 30% against Road Traffic One and also 10dB(A) Noise Reduction against Noise Barrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.338.2-338
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• 2002

Passengers in automobile or train are exposed to a worse noise environment when they are in the tunnel than in the open field. This is due to a relatively higher space density of sound energy by multiple reflection phenomenon of noise generated by operation of transportaton vehicles from tunnel wall compared to open field. In this study, noise characteristics of subway train running through a tunnel were investigated at straight/cruved track and tunnel type(semi circula/box). (omitted)

• Journal of Environmental Health Sciences
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• v.19 no.4
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• pp.9-13
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• 1993

This paper describes the impact of reflected sound in tunnel. The impact of reflected sound is obtained from making a comparision between measurements of tunnel and bridge. Sound level of tunnel is higher than that of bridge because reflected sound is generated in tunnel. Road traffic noise cannot be freely propagated because there are many buildings in urban. Therefore, a tunnel effect is generated in urban road. The impact of reflected sound is generated not only in tunnel, but also in urban road. This study provides the basic data for tunneling work and noise control strategy in urban road.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.542-547
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• 2004

The objective of this study is 0 estimate wind pressure acting on soundproof tunnel and noise reduction through the tunnel. For the purpose various shape of scale models were prepared and drag forces acting on each models were measured in wind tunnel. And numerical simulation was performed to confirm experimental results. As a result the lowest drag force coefficient of 0.59 was obtained in the case of arch roof shape model. Noise reduction through soundproof tunnel was simulated by using ray tracing method according to various open ratio of its roof area.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.627-635
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• 1997

In general, the booming noise intensity at tunnel exit is strongly related to the gradient of the compression wave front created by high speed train entering the tunnel. This paper presents some results in relation with the compression wave front produced when the high speed train enters a tunnel. Four kinds of tunnel entrance shape with real dimensions were studied to investigate the formation of compression wave front inside tunnel by train entering tunnel. Computations were carried out using three-dimensional compressible Euler equation with vanishing viscosity and conductivity of fluid. According to the reslts, the flow disturbance occured at tunnel entrance were eliminated by tunnel hood with same cross sectional area. The compression wave front is formed completely at 30-40m from tunnel entrance. The maximum pressure gradient of compression wave front is reduced by 29.8% for the inclined tunnel hood and reduced by 21.5% for the tunnel hood with holes at the top face with tunnel without hood. The length of the inclined hood is 15m and the length of the hood with holes is 20m.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.408-416
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• 2007

This paper summarizes an experimental study on the marine propeller BPF noise. The main objective of this study is to show the worthiness of the noise measurement at the MOERI middle size cavitation tunnel and to acquire useful propeller noise data. Background noise of MOERI(Maritime and Ocean Engineering Research Institute) cavitation tunnel is experimentally analyzed. Experiment carried out in the MOERI cavitation tunnel with wake screen or dummy body, which is simulated the wake. Propeller BPF noise is measured under various operating conditions. In order to secure the reliance of measured propeller noise dada, background noise of each operating conditions are measured and analyzed. The noise characteristics are analyzed according to the operating condition.