• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.783-788
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• 2004

Recently, Statistical Energy Analysis(SEA) is being increasingly applied to describe vibro-acoustic behavior of complex structures, such as air plane, automobile, ship, building. In this paper, we discuss the application of SEA to predict the interior noise for KTX train. To validate the SEA model of KTX train, calculated the interior noise for motorized car is compared to measured one. Finally, the reduction measures of interior noise for KTX are also discussed.

• 소음진동
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• 제10권5호
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• pp.806-810
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• 2000

This paper presents a practical method for reduction of interior noise and improvement of sound quality in compartment of passenger car. The tested vehicle has a booming noise problem at rear passenger seats. In order to identify the transfer path of interior noise, the running modal analysis, the vibro-acoustic frequency transfer response and the noise path analysis are systematically employed. Using these various methods, it has been founded that the rear part of the roof of the test car was a noise source for the booming noise. Through the modification of the roof, the booming noise has been reduced and sound quality inside car also has been improved.

• 소음진동
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• 제10권4호
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• pp.629-635
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• 2000

Wheel /rail interaction has been known as a major source of railway noise. In this paper, a low noise wheel structure is developed and its effect on noise reduction is investigated. The developed low noise wheel employees a rubber material inserted into a steel rim or mounted on the wheel surface. Since the low noise wheel has low stiffness and high damping ratio compared to a solid wheel, the measurement results show that it reduces the rolling and squeal noise. It turns out that the proposed wheel could reduce interior noise level by 4∼5dB(A) and vehicle vibration level by 7∼10 dB. Although the proposed structure seems to be promising in noise reduction of railway vehicles, the low noise wheel is to be verified in endurance and cost effect.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.942-946
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• 2010

As the major sources of interior noise of train at running condition are the wheel/rail contact noise, the traction motor's noise and the driving gear's noise and these noise sources are transmitted through the car body, the noises of HVAC and air duct can be ignored. But the interior noise of train at standstill condition is decided by HVAC's noise and noise from the diffuser through the air duct. the interior noise prediction of train at standstill condition should be performed considering the shape of air duct, the air velocity and noise reduction property inside the air duct. But it is hard to estimate the interior noise level by the numerical method. Therefore train maker predict the interior noise level using The commercial noise prediction program. This paper introduce the noise prediction method of the train at standstill condition using the commercial program appling the ray tracing method and statistical energy analysis.

• 한국소음진동공학회논문집
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• 제17권11호
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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.

• International Journal of Automotive Technology
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• 제8권5호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.789-792
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• 2005

The dominant noise sources of Diesel Multiple Units are powerpack, which is composed of engine, transmission and cooling system, noise and wheel-rail rolling noise. The interior noise of a running vehicle is determined by structure-borne noise and air-borne noise from these noise sources. The contributions of interior noise from each noise source are calculated by air-borne transfer functions and structure-borne transfer functions of noise sources. In this paper, source separation technique is proposed to determine these transfer functions from the results of stationary and running tests of existing vehicle. With this technique, it is possible to get hold of contributions of interior noise from .noise sources of running vehicle. This source separation technique makes it possible to take efficient measures for reduction of interior noise at the early car-development stage.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1413-1419
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• 2008

As the improvements of service quality is becoming an important issue the, interior noise level of a train is an important factor of comfortable ride. To reduce the interior noise level, noise sources of the train need to be removed. However, in case with a structure of large scale and multiple noise sources, an estimation of influences of major noise sources, with indentification of its traveling paths needs to be performed. In current state, to improve the interior noise reduction, consideration of sound transmission loss of the train body prior to manufacturing is usually performed. In this study, the sound transmission loss of the train body of new model train of seoul metro's line no.2 under test opeation is measured and modeling of the train body is performed. And train interior noise is predicted using the measured values.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.29-30
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• 2006

The interior noise of KTX in tunnel has become an issue since the commercial operating in April 2004. The analysis of the interior noise of KTX in tunnel with concrete track shows sharply increased noise level in the range of 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 noise outside gangway and rolling noise at the carbody natural frequency. In this Study noise reduction methods are discussed on the basis of the comparison of the KTX and KHST noise characteristics. Alternatively, the effect of the modified mud-flap on the interior noise is introduced.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.265-272
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• 1998

In this paper, the intoner noise reduction for subway railroad vehicles was studied by improving transmission loss of carbody panels and side doors, and on-line tests were conducted to examine the exterior noise levels at various running conditions. Also the transmission loss for design candidates of the carbody specimen was measured in two reverberation rooms. From the results of the tests, side door gap is the most dominant factor affecting the Interior noise level of subway railroad cars with a sliding typed side door. The next one is revealed to transmission loss of a floor panel. To improve the transmission loss of the carbody, many activities were conducted such as, treatment of resilient and sound-absorbing materials and reducing the gap of the side door by adopting a brush and rubber, etc. The estimated interior noise level for modified car which is designed with improved carbody panels is lower than original car by about 5㏈.