• Title/Summary/Keyword: 진동파워

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Rotordynamic Design and Stability Prediction of 100 Watts Micro Power System (100 Watts 급 초소형 파워 시스템의 회전체 동역학적 설계 및 안정성 예측)

  • Kwak, Hyun-Duck;Lee, Yong-Bok;Ryu, Keun;Kim, Chang-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.459-464
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    • 2003
  • The Roordynamic feasibility of Micro Power System supported by air foil bearings is investigated. The Micro Power System is new portable power source based on brayton cycle, which consists of compressor, turbine, generator, and combustion chamber. In this paper, the analysis of Rotordynamic characteristics of Micro Power System is performed based upon the bearing equilibrium position, Campbell diagram and stability. As a result, it is demonstrated that the air foil bearings could be adopted well to the Micro Power System. However, for more stable operation at target running speed, the damping characteristics of air foil bearing should be enhanced.

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Experimental Methods for the Measurement of Damping Loss Factors (내부손실계수 측정을 위한 실험 방법)

  • 김관주;최승권
    • Journal of KSNVE
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    • v.9 no.6
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    • pp.1187-1192
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    • 1999
  • The purpose of this study is to determine the most appropriate experimental method of the measurement of "damping loss factors" (DLF) for the statistical energy analysis(SEA) calculation. The successful prediction of vibration levels from the structure is critically dependent on the accurate estimation of DLF's not only in conventional vibration analysis but especially in SEA. Unforunately, calculation of accurate DLF is not an easy matter. So experimental methods are made use of for the DLF values. Three kinds of experimental methods for estimating DLF, i.e. decay rate method, half-power bandwidth method and power balance method, are presented and tests are carried out for the plate and the cylindrical shell examples. Pro and con of each methods is reviewed. Finally, calculated DLF values are used for vibration level estimation using commercial SEA software and compared with measured vibration data.tion data.

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A Study on Vibration Power Flow of Truss Core Type Sandwich Plate Structure (트러스코어형 샌드위치 판구조물의 진동파워흐름에 관한 연구)

  • 구경민;김동영;홍도관;박일수;안찬우;한근조
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.863-866
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    • 2002
  • In this study, we tried to grasp the characteristic of vibration power flow for the truss core type sandwich plate structure. As the result of the finite element analysis, this paper shows that the vibration power flow characteristic of truss core type sandwich plate structure is understood and the vibration power flow of upper plate according to the mode shape of structure is various. Also it presents the vibration power flow is affected by reinforced structure.

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Prediction of Highway Traffic Noise - Estimation of Sound Power Level Emitted by Vehicles (고속도로 교통소음 예측-자동차 주행소음의 음향파워레벨 평가)

  • 조대승;오정한;김진형;김성훈;최태묵;장태순;강희만;이성환
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.8
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    • pp.581-588
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    • 2002
  • Precise highway traffic noise simulation and reduction require the accurate data for sound power levels omitted by vehicles, varied to road surface, traffic speed, vehicle types and makers, different from countries to countries. In this study, we have elaboratively measured Korea highway traffic noise and parameters affecting noise levels at the nearside carriageway edge. From numerical simulation using the measured results for highway traffic noise, we propose not only two correction factors to enhance the accuracy of Korea highway traffic sound power estimation using ASJ Model-1998 but also its typical power spectrum according to road surface type. The measured and predicted highway traffic noise levels using the proposed sound power show little difference within 1 dB.

A Study on the Errors at the Measurement of Sound Power (음향파워 측정 시 오차에 대한 고찰)

  • Na, Hae-Joong;Lim, Byoung-Duk
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.10
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    • pp.917-924
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    • 2012
  • Noise power of large machineries, such as textile looms, winders, and twisting machines, is often measured in a reverberant space because they cannot be installed and operated in an anechoic chamber due to their size, weight, and operating conditions. Factors affecting the measurement error of an in-situ noise power measurement include the nonuniform reverberation time and the direction of sound intensity vector which is usually regarded as normal to the measurement surface. In this study errors due to these factors are estimated with the aid of numerical simulation based on the ray-tracing technique. The averaging of reverberation times measured at several points on the measurement surface is suggested to reduce the errors from nonuniform absorption. Also the direction cosine of each surface element is taken into account, which as a whole is represented as a solid angle of the measurement surface.

Prediction of HVAC System Noise by Acoustic Power Balancing Method (음향파워 평형방법을 이용한 HVAC 시스템 소음예측)

  • 홍진무;최태묵;김병희;조대승;김동해
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.1306-1312
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    • 2001
  • In this study. the acoustic power balancing method to analysis HVAC system noise is presented. The method can consider not only forward but also backward propagations of noise generated by the operation of air supply units and aerodynamical disturbance at duct elements. This can be done by estimating sound transmission and reflection properties of duct elements. and balancing acoustic powers of total HVAC system. To verify the accuracy of the presented method. numerical analysis for a HVAC system is carried out and the results are compared with those obtained by a traditional empirical method. suggested by National Environmental Balancing Bureau.

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Analysis of sound radiation by floor vibration in the closed sound field (실내의 바닥진동에 의한 음향방사해석)

  • 최석주
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1992.06a
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    • pp.137-140
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    • 1992
  • 실내 바닥슬래브의 휨진동에 의한 음향방사문제에 대하여 유한요소법을 적용하여 검토하였다. 단순한 형상의 판이 휨진동하여 자유공간에 음을 방사하는 문제에 대해서는 이론적인 해를 구할 수 있으나, 임의형상의 판이 휨진동하여 실내에 음을 방사하는 문제에 대해서는 검토되지 않았다. 따라서 본 연구에서는 이와같은 문제를 단순화한 해석법으로서 먼저 유한요소법을 이용하여 판의 휨진동에 대한 고유모드의 상대변위를 구하고, 다음 상대변위를 진동속도로 변환한 결과를 입력조건으로 하여 유한요소법에 의한 3차원 음장해석을 하였다. 그 결과 실내 바닥슬래브의 휨진동에 의한 음향방사파워는 슬래브의 진동모드, 실내음향모드 및 벽흡음율 등의 조건에 따라 크게 변화된다는 것을 확인하였다.

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Dynamic Response Analysis of Caisson-Type Breakwater Using Wave-Induced Ambient Vibration (파랑유발 상시진동을 이용한 케이슨 방파제 구조물의 진동응답분석)

  • Lee, So-Young;Yi, Jin-Hak;Nguyen, Khac-Duy;Lee, Po-Young;Kim, Jeong-Tae
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2011.04a
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    • pp.606-609
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    • 2011
  • 본 연구에서는 실제 케이슨 방파제 구조물의 진동기반 안정성 평가를 위한 기초연구로서, 현장실험을 통해 케이슨 방파제 구조물의 진동응답을 분석하였다. 이를 위해 첫째, 대상구조물로서 부산항 오륙도 케이슨 방파제를 선정하였다. 둘째, 파랑에 의한 상시진동 가속도응답을 계측하였다. 마지막으로, 계측된 가속도신호로부터 파워스펙트럼밀도함수, 고유진동수 및 모드강성도 분석을 통해 케이슨 방파제의 진동특성을 분석하였다.

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An Investigation of Power Flow Mechanism in Beam-plate Built-up Structures with an Energy-absorbing Plate (보-판 결합 구조물에서 에너지 흡수체로 작용하는 판의 특성에 따른 파워 전달 특성에 관한 연구)

  • Yoo, Ji-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.1 s.118
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    • pp.55-64
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    • 2007
  • In the built-up structure consisting of a stiff beam and a flexible plate, Grice showed that the plate behaves as an energy absorber in narrow frequency bands(called plate blocking effect). This paper deals with such beam-plate coupled structures, where the plate is an energy absorber and the excited beam is an energy path. It is found that such energy dissipation can occur in the relatively broad bands, if different stiffnesses are used in the rectangular plate. It was experimentally verified by Heckl that the energies in terms of one-third octave band averages transferred to the plate(or dissipated in the plate) increase for increased plate damping. This Paper, however, shows that the energy absorption suddenly reduces at the certain narrow frequency bands where the plate damping effect upon the coupled beam is maximum. Also, in order to minimize energy transfer through the beam in terms of one-third octave band averages, it is advantageous to increase the plate damping closer to the excitation point All these results are based on the wane method.

Development of Power Amplifier for Piezoelectric Actuator and Control Algorithm Realization System for Active Vibration Control of Structures (구조물 능동진동제어를 위한 압전 작동기 구동 파워앰프와 제어 알고리즘 구현 시스템의 개발)

  • Lee, Wan-Joo;Kwak, Moon-K.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.2
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    • pp.170-178
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    • 2012
  • This paper is concerned with the development of power amplifier and controller for piezoelectric actuator and sensor used in smart structures. Even though a high-voltage power amplifier is provided in the form of an operational amplifier, a very high DC voltage is still necessary as a power supply. In this study, we propose a low-cost design for the power amplifier including the DC power supply. We also need a controller on which a control algorithm will be mounted. In general, a digital signal processing chip is popularly used because of high speed. However, only commercial product is available for smart structure applications. In this paper, a controller consisting of a DSP and electronic circuits suitable for piezoelectric sensor and actuator pair is proposed. To validate the proposed controller with power amplifier, experiment on smart structure was carried out. The experimental results show that the proposed control system can be effectively used for smart structure applications with low cost.