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전달경로분석법을 이용한 상용 전기 차량의크립 그론 소음 저감 연구
박우엽,전주현,유성호,강연준 한국소음진동공학회 2022 한국소음진동공학회 논문집 Vol.32 No.4
Creep groan noise is a low-frequency, structure-borne noise that generally occurs when a vehicle starts moving from a standstill or comes to a gradual stop with minimal brake operation. It is generated by friction-induced vibrations from the stick-slip cycle of the brakes and are typically transmitted through the suspension. The investigations in this paper aim to reduce the creep groan noise by considering the frequency characteristics of the suspension. Transfer path analysis (TPA) is performed to identify the noise contribution of each suspension component. Thereafter, the cause of acoustic amplification and stick-slip cycle of creep groan are investigated through modal testing on the primary transfer path components. The noise level and trigger rate of creep groan noise are reduced by suppressing the behavior of the components using a dynamic vibration absorber (DVA). This shows the possibility of creep groan noise reduction from the perspective of the vehicle’s transfer system.
申文燮,文秀男,洪聖根,朴雨燁 群山大學校 1996 論文集 Vol.23 No.-
The field observation of the tide and tidal current in Saemangeum reclamation area was carried out by Rural Development Corporation in Korea for about a month (1994. 8). Measured values of tides and currents in the field were used for the boundary conditions in the numerical calculation. The amplitudes of M₂tide current after the dike construction has decreased about 15 to 50 ㎝ s¹㎝ than before the dike construction. The phase after the dike construction has increased about 3˚to 6˚ than those prior to the dike construction. The calculated tide-induced residual current by M₂tidal current, which obtained by averaging calculated tidal currents over one-tidal cycle, that after the dike construction. The speed of tide-induced residual current are very weak, that is, that is less than 5 cm s¹ in the Saemangeum coastal region with the exception at the mouth of Geum River and Mankyung River. A weak clockwise circulation is formed at the front of the dike.
박우엽,Jeon Heon Lee,김관주 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2
Urban rapid railway is one of the most popular transportation methods these days. It is equipped with large-capacity air compressors since it uses pneumatic pressure to supply power for braking and for opening and closing doors. Passengers tend to complain about vibration and noise from the air compressor. In this study, vibration reduction of air compressor was achieved by acquiring exact complex dynamic stiffness of the mounting rubber and optimizing the shape of it. Target stiffness values of the rubber was obtained from multi-body dynamics simulation of the air compressor-mounting system. Complex elastic modulus of the rubber mount was derived through EMA and Gent’s method and verified by finite element method. Through parametric study of mounting rubber, an optimal shape of mounting rubber was derived and produced. Lastly, the proposed value was verified by experiments comparing with baseline value.
전달경로기법을 이용한 철도차량 공기압축기의 전달력 예측
김관주,박우엽,이우형 한국철도학회 2019 한국철도학회논문집 Vol.22 No.2
Urban rapid transit systems are one of the most popular transportation methods. They are equipped withlarge-capacity air compressors because pneumatic pressure is required to supply power for braking and door openingand closing. To deal with passenger complaints regarding the vibration and noise generated during the operation of theair compressor, the following were considered. The excitation force generated in an air compressor mounted on a railwaycar was first indirectly measured. To accurately predict the excitation force transmitted to the mount rubber, theimpedance matrix method technique that uses acceleration and the inverse of the transfer functions was applied. Furtherinvestigation was conducted to determine the proper position to measure the acceleration. Then, the calculated resultsfor the transmitting forces were compared with the directly measured values.