• 터널과지하공간
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• 제12권3호
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• pp.210-219
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• 2002

구조물 발파해체시 발생하는 지반진동은 발파진동과 붕괴되는 구조물의 낙하에 의한 충격진동으로 구별되어 나타난다. 본 연구에서는 모형 구조물에 장전층을 달리하여 붕괴시켰다. 이때 발생하는 지반진동을 발파진동과 충격진동으로 구별하여 각 방향별 파형 및 주주파수를 분석하고 장전층의 변화에 따른 진동의 특성을 비교하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.144-149
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• 2008

In this paper, vibration sources of a car-holder are identified and the car vibrations are reduced by structural modification. For vibration identification, vibration signals are measured by an accelerometer when the car is moving. From some experiments and finite element analyses, it is also found that resonances occur because the natural frequencies of the car exist in usual driving speed range. To shift the natural frequencies outside the driving speed range, the connection part is modified to increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.220-225
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• 2001

Asymmetric beams cause complicated vibration phenomena due to the inherent bending-torsion coupled vibration. In this paper, an exact dynamic element matrix for the bending-torsion coupled vibration of asymmetric beam is derived. An application of the derived exact dynamic element matrix is demonstrated by an illustrative example, wherein the natural frequencies by the proposed modeling method are compared with those available in the literature. Another numerical example is also illustrated which deals with a general beam with joints. The numerical study shows that the exact dynamic element model is useful for the dynamic analysis of asymmetric bending-torsion coupled beams.

• 한국소음진동공학회논문집
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• 제18권6호
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• pp.681-689
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• 2008

This paper is concerned with the free vibration analysis of a circular plate with an eccentric circular hole by the Independent coordinate coupling method(ICCM). It was proved in the previous study that the ICCM can accurately predict the natural frequencies and mode shapes of the annular plates and can also be used for the free vibration analysis of the simply-supported circular plate with an eccentric circular hole. In this study, the clamped and free boundary conditions were considered for the circular plate. The numerical results show that the ICCM can be used effectively for the free vibration problem of circular plate with an eccentric hole compared to the finite element method.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1086-1092
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• 2007

This paper is concerned with the vibration analysis of a rectangular plate with multiple circular holes. On the contrary to the case of rectangular plate with multiple rectangular holes, it is very difficult to perform qualitative analysis on natural vibration characteristics because of geometrical inconsistency. 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 circular 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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1900-1906
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• 2000

In this study, the vibration screening effectiveness of barriers which can isolate structures from ground-transmitted vibration generated by harmonic forces is performed. For high frequencies, the vibration screening effectiveness of barriers is analyzed from field tests, and compared with the results from numerical analyses using a commercial program, ANSYS. Using these numerical analysis procedures, the effectiveness for vibration with various low frequencies is predicted. The frequency analysis tests of surface waves are performed in order to estimate the dynamic material properties of soil for 100 Hz, 150 Hz, 200 Hz, and 250 Hz. Three-dimensional solid elements are used in order to consider the diffraction of waves in all directions. Spring-damper combination elements are used in order to avoid the reflection of waves on the boundary. The results of numerical analysis agree with those of field tests. From the results of this numerical analyses, the reduction of vibration for low frequencies induced by the traffic loads can be predicted.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1027-1033
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• 2000

This paper describes the characteristics of vibration of a hydraulic turbine mainly due to cavitation occurrence. The analysis of vibration spectra of the turbine shaft shows that hub vortex cavitation occurs in the downstream of the turbine runner, which is verified from coherence analysis between shaft vibration displacement and dynamic pressure at the draft tube. Even though acceleration level measured at the guide vane lever, which is usually used for evaluation of cavitations performance, is decreased during forced aeration, it is found from the analysis of dynamic pressure spectra that cavitation around runner blades still remains unchanged. It is also found that lateral vibration of the turbine shaft is mainly due to the hub vortex cavitation of the turbine runner.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.71-76
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• 2011

In this paper, we investigate the vibration source of sheet feeding apparatus installed in scanner cover of the digital MFP through frequency analysis. Gearmesh frequency and motor generated frequency were calculated to analyse autospectrum. During driving state, we measure the vibration level. It was found from the signal analysis that gearmesh frequency and motor generated frequency are identified as vibration source.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.602-606
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• 2011

In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent reduced elastic tower is supported to the VAWT so that the elastic stiffness effect of the tower can be reflected to the present vibration experiment. Various excitation sources with aerodynamic forces are considered and the dominant operating vibration phenomena are physically investigated in detail.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.916-921
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• 2006

Column mixer is one of the facility to mix fluids at petrochemical plants. The column vibration is caused by pumps for fluid inflow and mixing of inside fluids. This fluid induced vibration is mainly responsible for the reduction of column life. Measurements were performed three times for understanding the vibration characteristics of the column. First experimental results showed the need of stiffness reinforcement. After the reinforcement work, second measurement conformed the difference between two results. Modal analysis was also performed to investigate the resonance of the column vibration and the damage of the rib plate. To confirm the generation of the fluid instability in the column mixer fluid structure interaction analysis using ADINA/FSI was performed which showed the necessity of the modification of the rotary valve.