• Title/Summary/Keyword: Noise and Vibration Characteristics

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Study on Acoustic Resonance of Air-conditioner Fan BLDC Motor (에어컨 홴 BLDC 전동기의 음향공진에 관한 연구)

  • Lee, Hong-Joo;Kwon, Joong-Hak;Lee, Chang-Min;Hwang, Gun-Yong;Hwang, Sang-Moon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.9
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    • pp.863-869
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    • 2009
  • Acoustic noises generated during motor operation in mechanical system are from electromagnetic, mechanical, aerodynamic and electrical sources. For identification of mechanical noise origins, misalignment, unbalance, fan shape, resonance, and vibration modes have been extensively considered to describe noise behavior. An experiment-based approach as well as a mathematical approach needs to be adopted for a realistic study into noise and vibration of the motor, because motor noise characteristics differ from type to type due to various noise sources. This paper analyzes noise characteristics of a brushless DC motor for air-conditioner fan, and proves that the test motor noise originates from acoustic modes of airspace in the motor. The motor noise sensitivity analysis by design of experiments reveals that the noise characteristics are closely related to switching frequency and frame thickness.

Characteristics of Wave Transmission Through Various functions in Coupled Beams (연성보에서 연결 구조에 따른 파동 전달 특성)

  • 이병철;길현권;이효행;이용현;홍석윤
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.468-473
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    • 2004
  • The objective of this paper is to analyze the characteristics of wave transmission through various junctions in coupled beams. The in-plane vibration as veil as the out-of-plane vibration are generated due to the wave conversion at the junctions in the coupled beams. The out-of-plane vibration is associated with propagation of out-of-plane waves (flexural waves). The in-plane vibration is associated with propagation of in-plane waves (longitudinal and torsional waves). In order to effectively reduce vibration and structure-borne noise, it is necessary to understand the characteristics of wave conversion at various junctions in the coupled structures. The numerical results in this paper have showed the characteristics of wave transmission through various junctions in coupled beams. Those could be helpful to designer to develop the idea to reduce vibration and structure-borne noise.

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A Study on the Characteristic of Noise and Vibration in 3-Phase Induction Motor for the Forklift (전동 지게차용 3 상 유도 모터의 소음 진동 특성에 대한 연구)

  • Kim, Woo-Hyung;Chung, Jin-Tai
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.764-769
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    • 2007
  • This paper is studied the noise and vibration characteristics analysis of the three-phase induction AC motor of the electrical forklift. And we suggest the method which the reduction orders the noise and vibration to be the mechanical. In other to investigate these characteristics, we considered the mechanical characteristics, the electromagnetic effects, and these interactions. In mechanical, we studied the characteristic of the stator, the bearing supported condition of the rotor, and the sound radiation. In electronically, this paper is considered the harmonic effect which is related the magnetic motive force (mmf) with respect to the characteristic of the slot number of the rotor and the stator and the pole number of the motor. Finally we investigated the overall noise and vibration of the induction motor by relations between the electronically harmonic and the mechanical resonance of the stator. By the analysis of the generally three-phase induction motor, we suggest the design methodology to low noise and vibration.

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An Experimental Study on the Noise and Vibration Characteristics of LCD TV Inverter (LCD TV 인버터 소음 및 진동 특성의 실험적 연구)

  • You, Chung-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.9
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    • pp.982-989
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    • 2008
  • There is a noticeable hum from the inverter board of LCD TV when in operation. In this study, we investigate the source and the characteristics of this noise for the inverter board of LCD TV using measurement of vibration and noise. Modal analysis of vibration and noise is visualized for identification of noise sources and transmission vibration. The main source of noise was the transformer of the LCD TV inverter. A noise reduction was achieved by damping the structural elements.

Comparison of vibration and Noise Characteristics for Reciprocating Air Compressor through the Change of Crankshaft Parameters (크랭크샤프트의 형상 변경을 통한 소형 왕복동 공기압축기의 진동 및 소음 특성 비교)

  • Park, Sang-Gil;Lee, Hae-Jin;Aminudin, Bin Abu;Lee, Jung-Youn;Oh, Jae-Eung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.530-533
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    • 2005
  • Recently, modern reciprocating air compressors tend to be smaller and lighter. But, as the development of performance, they have many problems for noise and vibration. For this reason, many researches are processing for the reduction of noise and vibration by arranging cylinders with V/W type. Especially, noise and vibration problems of reciprocating air compressor cause a rotating unbalance of crankshaft, so it needs a change of crankshaft parameters appropriately. Hence in this study, we changed crankshaft parameters to solve the rotating unbalance and compared results in order to verify the noise and vibration reduction between new and original air compressor. According to modify a crankshaft parameter, the improvements of noise and vibration were showed results of spectrum measured at selected points of the air compressor crankshaft housing and sound intensity contours measured at a belt left side, table that figure out characteristics of noise. Furthermore, we analyzed objective sound quality metrics with recording data of systems. The results showed that, the new design has improved the level of the first harmonic of vibration displacement, noise and objective sound quality metrics.

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A Study on Noise and Vibration Characteristics of Pipe Structures (파이프 구조물의 소음 및 진동특성 연구)

  • 류봉조;임경빈;이규섭;송영봉;공용식;오부진
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.334-337
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    • 2002
  • The paper presents noise and vibration characteristics of three kinds of pipe materials (PVC pipe, cast-iron pipe and newly developed pp pipe). In order to measure structure bone noise, impact force using small balls was applied to earth pipe. It was confirmed that structure bone noise can be reduced by more large damping materials. Also, transmission loss of pipes depending on the frequency ranges was investigated by using sound source through speakers.

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Noise and Vibration Characteristics of Externally Pressurized Air proceeding Bearings with a Circular Slot Restrictor (원형 슬롯 레스트릭터를 갖는 외부 가압 공기 저널 베어링의 소음 및 진동 특성)

  • Park, Jung-Koo;Rho, Byoung-Hoo;Kim, Kyung-Woong
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1277-1282
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    • 2003
  • The purpose of the present paper is to investigate the noise and vibration characteristics of externally pressurized air proceeding bearings with a circular slot restrictor. To do this, the nonlinear transient analysis including rotor imbalance was performed for a rotor-bearing system. The effects of radial clearance and the width of the bearing and mass eccentricity of the rotor on the noise and vibration characteristics of the bearing are also examined. The results show that the noise and vibration of the rotor-bearing system first increase up to critical speed of the system, and then decrease up to instability threshold speed of the system as the rotational speed of the rotor increases, and the noise of the bearing is markedly influenced by the mass eccentricity of the rotor and the radial clearance and the width of the bearing.

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Prediction of Noise and Vibration Characteristics of Externally Pressurized Air Journal Bearings with a Circular Slot Restrictor (원형 슬롯 레스트릭터를 갖는 외부 가압 공기 저널 베어링의 소음 및 진동 특성 예측)

  • Rho, Byoung-Hoo;Park, Jung-Koo;Kim, Kyung-Woong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.6
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    • pp.1028-1033
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    • 2003
  • The purpose of this paper is to investigate the noise and vibration characteristics of externally pressurized air journal bearings with a circular slot restrictor. To do this, the nonlinear transient analysis including rotor imbalance was performed for a rotor-bearing system. The effects of radial clearance and the length of the bearing and mass eccentricity of the rotor on the noise and vibration characteristics of the bearing are also examined. The results show that the noise and vibration of the rotor-bearing system first increase up to critical speed of the system, and then decrease up to instability threshold speed of the system as the rotational speed of the rotor increases, and the noise of the bearing is markedly influenced by the mass eccentricity of the rotor and the radial clearance and the length of the bearing.

A Study on the Noise Generation Cause and Vibration Damping Characteristics of Shock Absorber (쇼크 업소버의 소음 발생 요인과 진동감쇠 특성에 관한 연구)

  • 신귀수;김경모;박태원;이기형;정인성
    • Journal of the Korean Society of Safety
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    • v.13 no.4
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    • pp.102-112
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    • 1998
  • Shock absorber has a great influence on the performance of the vehicle(ride comfort, manipulation, noise, vibration, turning, stability). Therefore, in this study we consider theoretically about general damper, variable damping oil damper, the control of vehicle Characteristics for the suspension, and undesirable phenomenon. And we measured the vibration/noise characteristics of shock absorber for the real car experimentation, strain change, and noise characteristics of shock absorber using experimental equipment. The study of domestic company and research institute on the vehicle shock absorber is active, but that of basis is not. So we think that they should be accomplished actively. Therefore, this paper will develop theoretical system on the vibration/noise characteristics of shock absorber by theoretical consideration and experimental result analysis of dynamic characteristics of shock absorber that were accomplished in this study. Then we will use it as the optimistic design data for shock absorber development.

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Heavy-weight floor impact noise propagation in a multi-story building (다층 공동주택의 중량충격원 전파 특성 해석)

  • Lee, Sinyeob;Hwang, Dukyoung;Park, Junhong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.225-226
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    • 2014
  • In multi-story buildings, heavy-weight floor impact noise propagates through multiple layers. In order to evaluate the influence of structural vibration and propagation, the actual twelve-story building was excited by an impact ball. Sound and vibration responses of each floor was measured using accelerometers and a microphone. Vibration characteristics and its transfer paths were different depending on the excitation floor locations due to differences in the structural characteristics. From the measurement result, transfer characteristics were quantified by statistical energy analysis. It was confirmed that the heavy-weight floor impact noise influence not only adjacent floor. The impact noise transferred and affected multiple layers.

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