• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.421-428
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• 2004

Acoustic response control of a corner-pinned plate using piezoelectric wafers was studied, both theoretically and experimentally. Three different sizes of aluminum alloy plates were used and available ball joints were employed to hold the plate at the four corners. The plate with the largest aspect ratio showed the largest and most clear responses to the acoustic excitation in the range of frequencies (0～200Hz), and sound pressure levels (80～100dB) as predicted. The reduction of the acoustic response of the plate by piezoelectric actuator was very significant, more than expected, but abatement of the sound transmission through the plate was only slightly altered by the piezoelectric actuator. This work is an original work extending earlier work with doors excited by acoustic fields. The important difference is the used of ball joints to simulate the joints.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.13 no.3
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• pp.73-84
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• 2005

Hanseo University's Tae-an Airfield was opened in July, 2005 for aeronautical education such as aircraft flight, air traffic control, avionics, etc., and will play an important part as a base for local economic and industrial developments. On the contrary, the aircraft noise from the airfield will give an impact against the vicinity of the airfield and become a big issue which the airfield authority has to solve. The aim of this study is to analyse the aircraft noise contour in vicinity of the airfield and to make understand the people around the airfield how much the aircraft noise will have an effect on. For the prediction of the aircraft noise in the local area, this study showed the method to assess the aircraft noise in the developed countries for aviation, and the result to compute WECPNL by INM 6.1 after encoding the various data including environmental input data, tract, and profile. The major results of the study can be summarized as follows ; While the area with influence contour of noise from 75 to 80 WECPNL is 0.555$km^2$, the area from 80 to 85 is 0.343$km^2$, and the area with influence contour of noise over 85 WECPNL is 0.163$km^2$. In addition, there are 4 houses in the contour over 85 WECPNL and the inhabitants(10 people) in this area will have effect from the noise. Therefore Tae-an airfeild authority is preparing the noise-prevention method or noise abatement program. Finally, according to the noise contour, it is one of the best way of decreasing the effect of aircraft noise that 33 runway is assigned as calm-wind runway because there is no resident in the area around 15 threshold.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1128-1133
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• 2003

A gas driven heat pump (GHP) core design comprises internal combustion engine, compressors incorporated to a cooling/heating system, rubber mountings and belt transmissions. Main excitation farces are generated by an engine, compressors themselves and belt fluctuation. It leads to high vibration level of the mount that can cause damage of GHP elements. Therefore an appropriate design of the mounting system is crucial in terms of reliability and vibration reduction. In this paper oscillation of the engine mount is explored both experimentally and analytically. Experimental analysis of natural frequencies and operational frequency response of the GHP engine mounting system enables to create simplified model for numerical and analytical investigations. It is worked out criteria f3r vibration abatement of the isolated structure. Influence of bracket stiffness between engine and compressors, suspension locations and damper performance is investigated. Ways to reduce excitation forces and improve dynamic performance of the engine-compressor mounting system are considered from these analyses. Implementation of the proposed approach permits to choose appropriate rubber mountings and their location as well as joining elements design A phase matching technique can be employed to control forces from main exciters. It enables to changing vibration response of the structure by control of natural modes contribution. Proposed changes lead to significant vibration reduction and can be easily utilized in engineering practice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.363-368
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• 2013

This paper relates to the electric braking, the permanent magnet synchronous motor vector control is suspended until the applied, and propose a new scheme by the controller in the observer to estimate the position and velocity using the Resolver speed detector. In addition, as a way to control the speed by braking torque at low speed, the pole of a stop just before the stop electrical braking. As a result, noise and dust abatement, consumption, reduction of the brake shoe increase the maintainability of comfort and energy use, enhances the effect of EMU performance improved sikyeoteum could see.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.10
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• pp.777-784
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• 2003

Acoustic response control of a corner-pinned plate using piezoelectric wafers was studied, both theoretically and experimentally Three different sizes of aluminum alloy plates were used and available ball joints were employed to hold the plate at the four corners. The plate with the largest aspect ratio showed the largest and most clear responses to the acoustic excitation in the range of frequencies (0∼200 Hz), and sound pressure levels (80∼100 dB) as predicted. The reduction of the acoustic response of the plate by piezoelectric actuator was very significant, more than expected, but abatement of the sound transmission through the plate was only slightly altered by the piezoelectric actuator. This work is an original work extending earlier work with doors excited by acoustic fields. The important difference is the used of ball joints to simulate the joints.