• Title/Summary/Keyword: Noise and Vibration Characteristics

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Comparison of track vibration characteristics for domestic railway tracks in the aspect of rolling noise (철도 전동 소음의 관점에서 해석한 국내 철도의 진동 특성 비교)

  • Ryue, Jungsoo;Jang, Seungho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.644-647
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    • 2013
  • The important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. The main contributors for rolling noise are the sleepers, rail and wheels. In order to analyze and predict rolling noise, it is necessary to understand the vibrating behaviors of railway tracks, as well as the wheels. In the present paper, theoretical modelings of the railway track are reviewed in terms of the rolling noise, and they are applied for the three representative types of domestic railway tracks operated: the conventional ballasted track, KTX ballasted track and KTX concrete track. The characteristics of waves propagating along rails were investigated and compared between the tracks. The tracks were modeled as discretely supported Timoshenko beams and compared in terms of the averaged squared amplitude of velocity which is directly related to the sound radiation from the rails.

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A Study on Dynamic Characteristics of Reciprocating Compressors (왕복동 압축기의 동특성 분석 및 진동개선에 관한 연구)

  • 고병승;황원걸;안기원;박성우;서문희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.478-485
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    • 2003
  • Today, although there have been high technical developments of a compressor in the respect of its capacity, it has been so hard to develop in the respect of vibration and noise because mechanical structure of it has originally numerous vibration and noise. However, if we can grasp the point of systematic phenomena of vibration and noise through the understanding of dynamic characteristics in mechanical equipment, it may be possible to consider countermeasures. In this study about a reciprocal compressor, the part of its machinery is modeled as rigid body, and the part of its spring is modeled as flexible body, and then they are analyzed by DADS. Each rigid body and spring are connected with joint torque of a motor is applied to shaft, and pressure is applied to a piston so that a compressor can be revolved. Based on this modeling, influence of a compressor's vibration is analyzed through changes of offset, connecting rod and crank radius In the case of weight balance, it I produced after re-design, and then changes of vibration of a compressor's inside are checked through experiments. These analysis data may help set measures of reducing vibration of a reciprocal compressor.

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Measurement of Dynamic Properties of Concrete Structures Using Beam Transfer Function Methods (보 전달함수법을 이용한 콘크리트 구조물의 동특성 측정)

  • Kim, Seung-Joon;Yoo, Seung-Yup;Jeong, Yeong;Jun, Jin-Yong;Park, Jun-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.950-953
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    • 2006
  • The floor impact noise of concrete structures in apartments buildings is affected from the flexural wave propagation characteristics. Accordingly, the measurement of wave propagation characteristics is required for suggestion of efficient method to reduce the impact noise. The purpose of this article is to propose an experimental technique to measure dynamic properties of concrete structures. The method was proposed using the flexural wave propagation characteristics. Wave speeds, bending stiffness and their loss factors are estimated from which the vibration dissipation capabilities are investigated. Several different concrete beam structures were custom-built for measurement. The damping treatments using viscoelastic materials for reducing noise generation are also tested. The beam transfer function of the damped beam is predicted using the compressional damping model from which the mechanism of the vibration energy dissipation is investigated.

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OPTIMAL DESIGN OF THE MULTIPLAYER DAMPING MATERIALS USING EQUIVALENT MODELING

  • Hur, D.J.;Lee, D.C.
    • International Journal of Automotive Technology
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    • v.5 no.3
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    • pp.189-194
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    • 2004
  • The viscoelastic layer material is widely used to control the noise and vibration characteristics of the panel structure. This paper describes the design technology of the effective vibration damping treatment using the concept of the equivalent parameter of viscoelastic layer materials. Applying the equivalent parameter concepts based on theories of shell, it is possible to simulate the finite element analysis of damping layer panel treatments on the vibration characteristics of the structure. And it is achieved the reduced computational cost and the optimal design of topological distribution for the reduction of vibration effect.

Vibration Localization of Open Loop Repeated Structures (개방형 반복구조물의 진동국부화)

  • 하동진;유홍희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.489-494
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    • 2003
  • Vibration localization characteristics of open loop repeated structures with mistuning are investigated in this paper. Mistuning of a periodic structure often creates significant non-uniformity in vibration responses. As a result of the localization, critical fatigue problems often occur in repeated structures. Therefore, it is of great importance to predict the vibration response of the mistuned repeated structures accurately. In this paper, a simplified model for the open-loop repeated structure is introduced and dimensionless parameters which influence the localization characteristics are identified. The effects of the parameters on the localization characteristics are investigated through numerical study.

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Analysis and Evaluation of the Brake NVH Characteristics for the Fusion-type Friction Material (퓨전형 마찰재의 브레이크 NVH 특성 해석 및 평가)

  • Kwon, Seong-Jin;Bae, Chul-Yong;Kim, Chan-Jung;Kim, Wan-Soo;Lee, Dong-Won;Lee, Bong-Hyun;Seo, Byoung-Youn;Jung, Kwang-Ki
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.606-607
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    • 2008
  • Nowadays, noise and vibration phenomena of a disc brake system have been given various names that provide some definitions of sound and vibration emitted such as grind, grunt, moan, squeak, squeal, judder and wire brush. The most common and annoying noise of a disc brake system is squeal noise. It is defined as noise whose frequency content is 1 kHz and higher with excessively high and irrigating sound pressure levels. In this paper, the noise and vibration characteristics of a disc brake system have been investigated to develop the fusion-type friction material, which overcomes the low steel and non-asbestos organic friction materials. For the purpose, both experimental evaluation and complex eigenvalue analysis have been carried out.

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Noise and Vibration Characteristics of Concrete Floor Structures Using Resilient Materials Driven by Standard Heavy Impact Source (완충재 유무에 따른 표준중량충격원에 의한 콘크리트 바닥 구조의 소음 및 진동 특성)

  • 송희수;전진용;서상호
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.8
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    • pp.661-667
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    • 2004
  • The characteristics of noise and vibration by a heavy impact source was studied. The triggering method was used for increasing the reliability and stability to measure the level of sound pressure. sound intensity and vibration acceleration. A simple finite element model and a rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The results show that the resilient materials decrease the natural frequency of the reinforced concrete slab, make a resonance with dominant driving frequency in the low frequency region, and increase the vibration and noise level. A simple finite element model and rigid body models was suggested to calculate the natural frequencies of the floor systems.

Experimental Study on Performance Tests of Vibration Source for Helical Gears (헬리컬 기어계의 가진원 성능 평가에 대한 실험적 연구)

  • Park, Gwang-Min;Kim, Chan-Jung;Lee, Jae-won;Lee, Bong-Hyun;Kim, Wan-soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.602-603
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    • 2014
  • A gearbox can be regarded as a self-exciting dynamic system, which has a vibration source. Transmission error (TE) is considered to be an main excitation source for gear noise and vibration. The TE excitation is transmitted through the gears, shafts, bearings, and housings. Thus, an experimental approach to each mechanical parts is useful in order to understand and evaluate the dynamic behaviour of a gearbox. This study is focused on the transmission and vibration characteristics of a helical gear system in development stage. In addition, by considering the tolerance factors and resonance characteristics, the vibration response of actual dynamic system is analysed.

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Characteristics Comparison of PM Motor according to the Driving method (영구자석형 전동기의 구동방법에 따른 전자기적 특성 및 진동 소음 비교)

  • Hong, Jung-Pyo;Lee, Su-Jin;Kim, Do-Jin;Lee, Byeong-Hwa;Jang, Woo-Kyo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.10a
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    • pp.522-527
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    • 2012
  • This paper presents a result of the mechanical noise and vibration analysis as well as the electrical characteristics analysis of the permanent magnet (PM) motor according to the driving method that is Brushless DC (BLDC) drive and Brushless AC (BLAC) drive. To do that, the characteristics of the PM motor, which have the same output power but different driving method, are investigated. At that time, the characteristics such as torque, torque ripple and flux density, and so on, are obtained by finite element analysis (FEA). Besides, noise and vibration are obtained by spectrum analysis. The magnetic noise is defined as noise generated from vibrations due to electromagnetic excitation force. In this paper, the electromagnetic excitation force is analyzed and design process of noise reduction is proposed. Finally, The validity of the analysis results is verified by test.

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