• Journal of KSNVE
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• v.10 no.4
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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.

• 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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• 2003.11a
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• pp.160-169
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• 2003

Pantograph of high speed rolling stock is one of the key components that transfer of associated technologies was blocked fundamentally from advanced nations. In this study, main technologies related to development of prototype pantograph installed on prototype test train developed according to the project "Development of high speed railway technology" are presented. Status of current korean technologies is explained by presenting developed technologies and applications during the past 6 years from concept design to test and evaluation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1535-1536
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• 2011

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.759-762
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• 2002

Automobile aeroacoustics Is a developing area of technology where experimental and theoretical tools are being continuously refined to understand, analyze and modify the noise-generating mechanisms in the vehicle flow. Main sources of ground vehicle exterior noise are the tires (tire/road interaction) and the unsteady flow field around the vehicle. In this study, the sound source localization of a rolling tire was applied to the measurement of radiated sound by using an acoustic mirror system. A possible flow pattern that develops is suggested based on detailed wind tunnel investigations with a rotating wheel in contact with a moving belt.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.438-441
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• 2004

Reduction of a ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargos as well as improving the comfort of the ride. A mass driving anti-rolling system (MD-ARS) might be one candidate of several systems against the ship's rolling. In this paper, a sea-trial test on a pendulum-type MD-ARS passively operated is carried out in Suyoung, Busan. After the system is installed on the cabin of the small leisure boat, a series of test is conducted before and after operating the system. Through the test, it is confirmed that the roll rate of the ship is pretty well reduced by the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.195-199
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• 2004

Recently, optical disc drives are required to have high density and capacity in according with development of high definition images and rapid increase of various informations. Consequently, the numerical aperture becomes larger, the wavelength of laser is coming to be short. However, it deteriorates rolling mode effect on an optical pickup actuator. Therefore, this paper proposes new design and optimization of tracking coils for reducing it. First, we verify that discord between the center of force and the center of mass by restrictions of design condition is an important factor of rolling mode effect. Then, in order to reduce it, we propose new design parameters of tracking coils. Finally, we reduce rolling mode effect through optimization of tracking coils using Taguchi method and response surface method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.775-779
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• 2003

Recently, a new type actuator using multi-pole magnet has been developed for high-density and high-speed disk drive, which can be achieved higher sensitivity than a conventional actuator for applying one-pole magnet. However, it is very difficult for the actuator of multi-pole magnet to meet simultaneously the optimal design condition for reducing rolling mode effect and improving driving sensitivity because the force center is different from the mass center In this paper, First We propose the new shape coil for tracking which can reverse moment additionally in tracking motion, Next we achieve the optimal design to reduce phase disturbance and peak gain at the rolling mode frequency. Finally, the validity of the proposed methods is proved from experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.727-730
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• 2004

Reduction of a ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargos as well as improving the comfort of the ride. A mass driving anti-rolling system (MD-ARS) might be one candidate of several systems against the ship's rolling. In this paper, three types of MD-ARS, two passive and one active devices, are developed for small ships. After they are installed on the cabin of the small leisure boat, respectively, a series of test is conducted before and after operating them. Through the test, it is confirmed that the roll responses of the ship are pretty well reduced by the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.666-671
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• 2014

To reduce the exterior noise level of EMU, there are several ways have been evaluated. The noise sources for the exterior noise level are the traction motor, driving gear and wheel/rail rolling noise. In this article, the ways to mitigate the noise issue for EMU have been investigated and especially the way to protect the noise radiation from the bogie area and wheel/rail rolling noise. The way to evaluate the effect of the side skirt has been reviewed. To install the side skirt, the interface between the side skirt and the carbody and bogie should be examined and the acoustic design of the side skirt will be evaluated.