• 제목/요약/키워드: radiated noise

검색결과 469건 처리시간 0.03초

주파수 응답 함수를 이용한 철도차량 실내소음 기여도 분석 및 분포도 측정 (Analysis of Noise Contribution using Frequency Response Function and Measurements of Noise Distribution for Railway Interior Noise)

  • 김재철;유원희
    • 소음진동
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    • 제9권5호
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    • pp.949-954
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    • 1999
  • Speed-up and mass reduction of railway vehicle usually causes increased of the interior noise. One of the best ways to control the interior noise is to identify the noise level radiated from each of parts in the cabin. In this paper, we describe the method to estimate the interior noise nad evaluate the noise contribution to each of parts. This method is based that the sound pressure can be calculated by using the frequency response function and acceleration. According to analysis of the noise contribution, we validated that the noise radiated from the floor is the higher in the cabin. We also measured the noise distribution for the side and floor by using the microphone array in order to analyze the effect of the noise flowing into the cabin from the outdoors. Finally, we presented the plan of the interior noise reduction based on the noise levels radiated from each of parts.

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파이프 내 흡음재 및 형상에 따른 유동 및 방사소음에 대한 수치해석적 연구 (Effect of the Inner Material and Pipe Geometry on the Flow and Induced Radiated Noise)

  • 이수정;임희창
    • 대한기계학회논문집B
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    • 제38권5호
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    • pp.423-430
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    • 2014
  • 파이프 유동 내에서 일어나는 소음 및 진동현상의 경우 일반적으로 난류유동과 근처의 벽면사이의 유동유기진동에 의해 일어나게 된다. 복잡한 난류유동을 가지는 확장관의 단순한 경우에서 본 연구는 수행되었지만, 방사소음의 경우 주어진 모델에서 크기와 형상 그리고 두께 등에 상당히 영향을 받게 된다. 또한, 방사소음은 그 파가 퍼져나가면서 주위 시스템에 교란특성이나 불안정성을 야기시키게 되는데 결국 중요한 파단과 파손을 일으키게 된다. 본 연구는 다양한 상용프로그램들 (Fluent, NASTRAN, 그리고 VIRTUAL LAB)을 이용하여 이러한 현상을 파악하고자 하였다. 이 연구를 통해 유동소음에 있어 깔려있는 물리현상들을 이해하고자 하였다. 확장관의 경우 단면적의 급격한 변화에 의해 박리와 높은 압력강하를 겪게 되는데, 방사소음의 계산으로 이 방사소음의 크기가 100에서 500Hz영역에서 전체적으로 약 20dB정도 감소시킬 수 있는 것을 확인할 수 있었다.

파워흐름해석법을 이용한 상선의 수중방사소음해석 (Underwater Radiated Noise Analysis for Commercial Ship Using Power Flow Analysis)

  • 권현웅;홍석윤;송지훈
    • 한국해양공학회지
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    • 제26권4호
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    • pp.30-36
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    • 2012
  • Recently, the underwater radiated noises generated from large commercial ships have become a globally important issue. Countries with large ports and environmental protection organizations demand strict safety guidelines in relation to underwater radiated noise. In this paper, the coupled PFFE/PFBE method is used to investigate the vibration and underwater radiated noise of a commercial ship. PFFEM is employed to analyze the vibrational responses of the commercial ship, and PFBEM is applied to analyze the underwater radiation noise. The vibrational energy of the structure is treated as an acoustic intensity boundary condition of PFBEM to calculate the underwater radiation noise. Numerical simulations are presented for the commercial ship under various frequencies, and reliable results are obtained.

방사효율과 방사방향 계수에 대한 새로운 산출기법 연구 (A New Extraction Method for the Radiation Efficiency and Radiation Directional Coefficient)

  • 정우진;이종주;강명환;전재진
    • 한국소음진동공학회논문집
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    • 제24권2호
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    • pp.93-101
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    • 2014
  • Underwater radiated noise is the key in acoustic stealth performance of modern naval ships. The underwater radiated noise predicted by the hull vibration with radiation efficiency cannot always give the information of radiation pattern which is essential to analyze of detection probability by enemy and to improve the operational performance of the naval ship. The radiation pattern of underwater radiated noise is able to be obtained with radiation efficiency and radiation directional coefficient. In this paper, a new method to extract the radiation efficiency and radiation directional coefficient is suggested and proved with the simulation and experiment by using cylindrical shell of 70 cm diameter in air.

기관 배기형의 머플러에서 압력맥동에 기대된 방사음에 관한 실험적 연구 (An Experimental Study on the Radiated Noise induced by Pressure Pulsation through Muffler in Engine Exhaust System)

  • 조경옥
    • Journal of Advanced Marine Engineering and Technology
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    • 제22권5호
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    • pp.635-642
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    • 1998
  • In automobile exhaust system. Internal pressure pulsation and shell vibration greatly affect the surface sound radiation. This noise is emitted from the muffler outer shell due to the pulsation of the exhaust gas pressure. This paper describes an analytical study of these characteristics as influenced by exhaust system structure. An exhaust simulator was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was identified by finding FRF.

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방사효율과 방사방향 계수 산출기법 연구 (A Study on the method for the extraction of the radiation efficiency and radiation direction coefficient)

  • 정우진;강명환;이종주;전재진
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2013년도 추계학술대회 논문집
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    • pp.738-743
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    • 2013
  • Underwater radiated noise is the key in acoustic stealth performance of modern naval ships. The underwater radiated noise predicted by the hull vibration with radiation efficiency cannot give the information of radiation pattern which is essential to the analysis of detection possibility by enemy and to improve the operational performance of the naval ship. The radiation pattern of underwater radiated noise is able to be obtained with radiation efficiency and radiation direction coefficient. In this paper, a new method to extraction the radiation efficiency and radiation direction coefficient is suggested and proved with the simulation and experiment by using cylindrical shell of 70cm diameter in air.

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철도차량의 전동음 예측에 관한 연구;- 지표면 효과 및 침목에서 방사되는 소음 계산 - (A Study on Prediction of Rolling Noise for Railway;- Calculation of Ground Effect and Noise Radiated by Sleeper-)

  • 김재철;정현범;이재응
    • 한국소음진동공학회논문집
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    • 제13권1호
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    • pp.56-62
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    • 2003
  • The major noise source for the conventional train is the rolling noise caused by the interaction of the wheels and rails during the train passage on the tangent track. In order to control the rolling noise, the noise radiated from wheels, rails and sleepers should be analyzed and predicted. In this paper, a prediction method of wheel/rail rolling noise generated by the roughness of the wheel/rail surface is described, where the method is considering the effect of noise radiated by sleepers and the effect of ground. The method is applied to the Korean railway system, and the sound pressure level (SPL) predicted by the proposed method is compared with the measured SPL. Overall. the result shows good agreement between the predicted and measured values.

압축기 쉘의 방사소음에 관한 연구 (A Study on Noise Radiation of Compressor Shell)

  • 채승훈;황원걸;오일권;박성우;류기오
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 추계학술대회논문집
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    • pp.164-167
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    • 2005
  • The noise level of refrigerating units is becoming more important to the manufacturer and the user of the product. Invariably, the compressor is a significant contributor to the overall noise level. Especially a major portion of the noise radiated by the vibration of the compressor shell. This paper presents an approach to relate the dynamic characteristics of the compressor shell with the noise radiation properties and the methods of redesigning the compressor shell to reduce the noise radiation. To relate the dynamic characteristics of the compressor shell with the noise radiation properties, the vibration and radiated sound were measured with the running compressor. Based on the results of these tests correlations between the shell vibration characteristics and the noise radiation properties are identified It was found that the vibration on the compressor shell and the noise radiated from the compressor were stronglycorrelatedincertainfrequencybands.

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가진력 규명을 통한 초고압 변압기의 구조진동 및 방사소음 예측 (Prediction of a Structural Vibration and Radiated Noise of High-voltage Transformer through Force Identification)

  • 유석진;정병규;정의봉;홍진숙;김태용
    • 한국소음진동공학회논문집
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    • 제23권6호
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    • pp.527-536
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    • 2013
  • In order to predict structural vibration and radiated noise of high-voltage transformer in operation, it is necessary to precisely find the excitation force generated by the coils and core. However, finding the excitation force through experiments of high voltage transformer in operation is not possible. Therefore, this paper deals with identifying the excitation force by using the acceleration data measured through experiments and the transfer function estimated through finite element model. A method to predict structural vibration and radiated noise was also proposed. Three-phase windings and the core are the source of high-voltage transformer. The excitation forces were identified using the acceleration data and the transfer function of the surface of the tank. Structural vibration and radiated noise from the surface of the tank was predicted by using the identified excitation force. As a result of the interpretation of the experimental and computational analysis of structural vibration from the surface of the tank and radiated noise from the field point, the interpretation of the computational analysis showed relatively good accordance with the experiment.

드럼세탁기 방사소음의 소스 및 기여도 분석 (Analysis of Sources and Contribution for the Radiated Noise of Drum-type Washing Machine)

  • 김지만;정병규;허소정;안세진;정의봉
    • 한국소음진동공학회논문집
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    • 제24권8호
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    • pp.628-635
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    • 2014
  • The procedure to estimate the sources of noise and vibrations in a typical drum-type washing machine was presented. The sources should be identified to predict the radiated noise with computational model of structure. Source identification techniques based on singular decomposition were implemented using the measured signals of accelerometers and microphones. The finite element analysis and indirect boundary element analysis were implemented to predict the structural vibrations and the acoustic pressures at the field points. The predicted results by only structural sources were compared with those by both structural and acoustical sources. It was verified that not only the structural-borne source but also air-borne source should be considered to predict the radiated noise with better accuracy. The contribution analysis with respect to the transfer path was also preformed.