• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.529-533
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• 2008

Recently in Korea, noise is one of the most important social issues because the living standard becomes more higher. Railway noise is also annoying one in our society, although railway has very positive role in our country. The major measures for mitigation of railway noise in Korea are rail welding and installation of noise barrier on the noisy area. But these measures have its own limit for the calm and comfortable living environment. In Europe the railway noise problem has been treated more systematically and aggressively, there has been emission noise standard for Trans-European rail network. In this paper, the trend of noise standard for railway vehicles will be reported and the check point for our country will be discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.133-138
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• 2001

Traffic noise is a significant national problem in many communities. Construction of noise barriers has been the most often used mechanism to mitigate vehicle noise for residents next to high density roadways. The most common materials for constructing noise barriers are metal. The character of the wall can be significantly modified by the type of surface treatment used on the wall body. Noise barrier walls can be softened through the use of plants. Greening Noise Barrier helps blend the roadway into the surrounding landscape and provides an interesting and aesthetic view of the road.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.97-103
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• 1999

As the noise of ship engine room is too loud, the engineer who works in a ship engine-room has the trouble of hearing. In this paper deals the investigation of the noise of ship engine room and cabins with the internationally allowable noise exposure level and noise exposure time. Recently, the problem of engine-room noise is more serious because of shipowner wants to make small number and larger size of cylinder. Therefore, engineers work in a ship engine-room for a long time have the trouble of hearing when they are exposed the high noise level. In this study, two kinds of vessels were used to investigate the noise of engine room, engine-control room, bridge, offices and cabins. As criteria of sound levels, A-weighted sound pressure level and octave band pressure level were used.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.38
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• pp.22-28
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• 2007

During the passage of the train, the railway bridge undergoes vibration and noise. The noise of railway bridge can be occurred from various sources. The wheel-rail contact, noise from machinery parts, structural-borne noise, pantagraph noise and aerodynamic noise of the train work in combination. Running train is one of the most important factors for railway bridge vibration. The repeated forces with equidistant axles cause the magnification of dynamic responses which relates with maintenance of the track structure and structure-borne noises. The noise problem is one of the most important issues in services of light rail transit system which usually passes through towns. In the present study, The vibration and noise of the LRT bridge will be investigated with utilizing dynamics responses from moving train as input data for noise analysis.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.605-614
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• 2007

This paper presents the research results for the reduction of a gear whine noise based on experimental and analytic methods. The test vehicle has a whine noise problem at the passenger seats in a sport utility vehicle. To identify the transfer path of the interior noise due to the axle system, a vibration path analysis, modal analysis and operational deflection shape analysis are systematically employed. By using these various methods, it has been found that the interior noise generated by the axle system was airborne noise. To reduce and predict the whine generated by the axle system, structural modifications for the axle system are performed by using FEM and BEM techniques. The structural modification of the axle cover is suggested for the reduction of whine noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.117-119
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• 2005

For large structural eigen-analysis, the whole structure is divided into some partitioned structures and through synthesis of partitioned structural model the eigen-data of structure can be obtained. In that case, eigenvalue problem consists of semidefinite mass matrix form because of displacement constraint condition. In this work the eigenvalue problem is considered by means of several method, determinant search and null space reduction method.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.37-38
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• 2007

This paper reviews the issues in implementing sound recognizers in real environments. First is the signal corruption caused by background noises and reverberation. Second is the open-set problem which is the problem of rejecting out-of-vocabulary words and noises. These two issues must be solved for noise robust recognizers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.382.1-382
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• 2002

This paper presents a new approach integrated Case-Based Reasoning with Self- Organization Map(SOM) in diagnosis systems. The causes of faults are obtained by case-base trained from SOM. When the vibration problem of rotating machinery occurs, this provides an exact diagnosis method that shows the fault cause of vibration problem. In order to verify the performance of algorithm, we applied it to diagnose the fault cause of the electric motor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.184-188
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• 2001

Severe vibration was detected during test operation in motor frame of the Turbo Chiller (300RT). To identify the vibration problem, vibration measurement and modal test were carried out. From the test results, it is concluded that the severe vibration occurred due to the resonance between the motor frame horizontal mode and the motor excitation frequency. Therefore the horizontal mode of the frame could be controlled by the sensitivity analysis results for the length of the supporting plate.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1920-1923
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• 2002

This paper proposes an impulse response shortening algorithm applicable to decision feedback equalization of single carrier wideband signal. When he impulse response shortening methods for narrowband signaling are applied to single carrier wideband signals, they result in noise enhancement problem, significantly deterioriting the receiver performance. This problem can be alleviated by educing the eigenvalue spread ratio of the impulse response, which can be achieved by adding additive white noise with small variance to the impulse response of the channel. The performance of the proposed scheme is verified by computer simulation.