• 제목/요약/키워드: Vibration problem

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축방향으로 이동하며 길이가 변하는 연속체의 진동특성: 스파게티 문제에 응용 (Vibration Characteristics of the Axially Moving Continuum with Time-Varying Length: Spagetti Problem)

  • 사재천;이승엽;이민형
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 춘계학술대회논문집
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    • pp.385-392
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    • 2001
  • Time-dependent frequency and energy of free vibration of the Spagetti problem, that is the axially moving continuum with time-varying length, are investigated. Exact expressions for the natural frequency and time-varying vibration energy are derived by dealing with traveling waves. When the string length is increased, the vibration period increases, but the free vibration energy varies as a function of both translating velocity and boundary velocity of the continuum. However, when the string undergoes retraction, the vibration energy increases with time, String tension together with non-zero instantaneous velocity at the moving boundary results in energy variation.

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300RT급 터보냉동기 진동원인 분석 및 해결방안 (The countermeasure for the Vibration Problem of Turbo Chiller (300RT))

  • 김관영;홍제민;배종국
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 춘계학술대회논문집
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    • pp.184-188
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    • 2001
  • Severe vibration was detected during test operation in motor frame of the Turbo Chiller (300RT). To identify the vibration problem, vibration measurement and modal test were carried out. From the test results, it is concluded that the severe vibration occurred due to the resonance between the motor frame horizontal mode and the motor excitation frequency. Therefore the horizontal mode of the frame could be controlled by the sensitivity analysis results for the length of the supporting plate.

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Spin Etcher의 진동 분석 (Vibration Analysis of Spin Etcher)

  • 임경화;이은경;조중근
    • 반도체디스플레이기술학회지
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    • 제2권1호
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    • pp.15-19
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    • 2003
  • Spin etcher can process frontside and backside on the wafer, which is used for etching, stripping, cleaning and wafer reclamation. A new generation of spin etchers has been designed to meet 300mm wafer processing. The larger header and higher spin speed make vibration problem a severe problem in developing equipments. This study shows schematic process of solving practical vibration problems, where it is required to analyze the principal ca uses of vibration problem and find out the method of vibration reduction in spin etcher. The vibration under normal operation is measured in time domain and is analyzed in frequency domain. And modal parameters are obtained through modal test. Using the modal parameters from experiments, the model of finite element method is formulated. From diagnosis using many measurements and analyses, it can be shown that main cause of vibration is unbalance of head.

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주기관 고차 관성기진력에 의한 콘테이너선 선루진동의 제어 (Control of Deckhouse Vibration of a Container Ship due to Higher Order Inertial Excitation of Main Engine)

  • 이수목;김원현;정균양
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.876-880
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    • 2000
  • Vibration problem of deckhouse structure in a container vessel was investigated through the analysis and measurement. The natural frequency of deckhouse structure was found to be resonant with main engine 4th order excitations in the operating range, major sources of which were main engine inertial moment and axial thrust of the propulsion shafting system. To investigate and solve the problem, exciter test was performed to identify the vibration chracteristics of the ship structure and mechanical balancer was installed to compensate the 4th order inertial moment. Measurement results under the conditions with and without balancer operating were compared and analyzed to confirm the balancer effect. Good coincidence was found between the measurement and analysis results, which made it possible to predict the vibration problem in the earlier design stage.

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독립좌표연성법을 이용한 여러 개의 직사각형 구멍을 갖는 직사각형 평판의 자유진동해석 (Free Vibration Analysis of Rectangular Plate with Multiple Rectangular Cutouts by Independent Coordinate Coupling Method)

  • 곽문규;송명호
    • 한국소음진동공학회논문집
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    • 제17권9호
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    • pp.881-887
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    • 2007
  • This paper is concerned with the vibration analysis of a rectangular plate with multiple rectangular holes. Even though there have been many methods developed for the addressed problem, they suffer from computational time. In this paper, we applied the Independent Coordinate Coupling Method(ICCM) to the addressed problem, which was developed to compute natural vibration characteristics of the rectangular plate with a rectangular hole and proven to be computationally effective. The ICCM is based on Rayleigh-Ritz method but utilizes independent coordinates for each hole domain. By matching the deflection conditions for each hole imposed on the expressions, we can easily derive the reduced mass and stiffness matrices. The resulting equation is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the Independent Coordinate Coupling Method.

페트리 네트를 이용한 사례기반 추론 진동진단시스템의 개발 (Development of Case-base Reasoning Vibration Diagnosis System)

  • 양보석;오용민;정석권
    • 한국소음진동공학회논문집
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    • 제11권9호
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    • pp.414-421
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    • 2001
  • If a machine has some faults, we can detect them using vibration or noise signals. However some maintenance engineers who don\`t have export knowledge, need the help of vibration experts for diagnosing the machine. In this paper a case based reasoning (CBR) system is developed which is able to manipulate the past experiences of vibration diagnosis experts. In the CBR system, the maintenance engineers can retrieve the information form previous cases which are most similar to new problem s that they can solve new problem using solutions form the previous cases. In this paper, a new case retrieval method of CBR system using Petri net is proposed and also applied to diagnosis for electric motors as a practical problem.

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Oil Whip에 의한 터빈의 이상진동 (Abnormal Vibration of Turbine due to Oil Whip)

  • 구재량;황재현
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.539-543
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    • 2001
  • Almost all rotating machinery has bearings. Bearing is one of the most important part of rotating machinery. Vibration of rotating machinery depend on its bearing conditions. Bearing conditions are followings ; oil gap, bearing type, bearing temperature, bearing oil condition. Especially, bearing oil condition influences on rotating machinery vibration directly. In this paper we have discussed the abnormal vibration of turbine due to oil condition. oil whip problem was occured in the certain power plant. and we had sloved this problem through the control of operating values and alignment.

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회전축 정렬불량 광디스크 드라이브의 진동 저감에 관한 연구 (A Study on Vibration Reduction of an Optical Disk Drive with the Misaligned Axis of Rotation)

  • 강봉진;정태은;신효철;오주환
    • 한국정밀공학회지
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    • 제21권5호
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    • pp.122-130
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    • 2004
  • In a high-speed and wide operating field optical disk drive, the vibration problem is one of the most important factors to be considered for reliable performance. And a disk misaligned with axis of rotation is a major source of vibration in optical disk drive. Furthermore, this vibration disturbance of the disk spindle system causes failure in the reading and writing process. So to solve this vibration problem, the vibration absorber using rubber mount has been introduced in recent years. In this paper, we have analyzed the simple optical disk drive model with dynamic vibration absorber through dynamic analysis of 12-dof by Recurdyn program and obtained optimal mass and frequency ratios of dynamic vibration absorber of dynamic vibration absorber and the optimal frequency ratio.

곡선진동원에서의 진동전파문제 연구 (Study of the propagation problem in the curved source of vibration)

  • 오장헌;허영
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.1112-1115
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    • 2004
  • Recently, KTX start service 2004 and speed up the Chung-ang line and Ho-nam line using tilting train. When the train speed up at curve the vibration environment are changed. It is the reason of the wave propagation problem in the curved source. In this research, using SSI Program SASSI, Predict the vibration propagation around the curved source of vibration. The curved source of vibration propagation is different from straight source of vibration propagation. In this study, made a curved vibration source model and compared with straight model.

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축방향으로 이동하며 길이가 변하는 연속체의 자유 진동 및 동적 안정성 (Free Vibration and Dynamic Stability of the Axially Moving Continuum with Time-varying Length)

  • 사재천;이민형;이승엽
    • 한국소음진동공학회논문집
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    • 제12권4호
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    • pp.272-279
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    • 2002
  • The time-dependent frequency and energy of free vibration of the spagetti problem, that is the axially moving continuum with time-varying length, are investigated. Exact expressions for the natural frequency and time-varying vibration energy are derived by dealing with traveling waves. The vibration period increases with increasing length, but the free vibration energy decreases. When the string undergoes retraction, the vibration energy increases with time. The free response of the time-varying string is represented by superposing two traveling waves.