• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.911-916
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• 2002

One of important roles of concrete track is to reduce vibration transmitting to subgrade. In this paper, a numerical method for evaluating the effects of vibration reduction of concrete track is presented. Using the method, high frequency dynamic analyses and track-tunnel-soil interaction analyses are carried out for three types of concrete track in order to investigate the vibration reduction effects compared with normal ballast track.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.679-686
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• 2000

Reactor Noise is defined as the fluctuations of measured instrumentation signals during full-power operation of reactor which have informations on reactor system dynamics such as neutron kinetics, thermal-hydraulics, and structural dynamics. Reactor noise analyses of ex-core neutron detector signals have been performed to monitor the vibration modes of reactor internals such as fuel assembly and Core Support Barrel in Yonggwang 3&4 Nuclear Power Plant. A real time mode separation technique have been developed and applied for the analyses. It has been found that the first vibration mode frequency of the fuel assembly was around 2.5 Hz, the beam and shell mode frequencies of CSB(Core Support Barrel) 8 Hz and 14.5 Hz, respectively. Also the analyses data base have been constructed for the continuous monitoring and diagnose of the reactor internals.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.607-613
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• 2011

In this study, structural vibration analyses for a 5MW offshore wind wind-turbine model have been performed for different substructure models. The efficient equivalent modeling method based on computational multi-body dynamics are applied to the finite element models of the present offshore wind turbines. Monopile and tri-pod substructure types of the typical offshore wind-turbine are considered herein. Detailed finite element modeling concepts and boundary conditions are described and the comparison results for previous analyses are presented in order to show the verification of the present numerical approach. Campbell diagrams are also present to investigate the rotational resonance characteristics of the offshore wind-turbines with different substructures.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.314-322
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• 2007

In general, the vibration and structural analyses have been carried out by using each finite element model separately because of different size of finite element mesh and different focusing area of each analysis. In some cases, however, it is required to perform both global vibration and structural analyses at the same time using a finite element model for global structural analysis, which asks for a special treatment for a vibration analysis. In this study, a technique to perform a global vibration analysis using a finite element model for a global structural analysis has been developed and its effectiveness has been verified by its application to a whole ship.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.937-948
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• 2006

In this study, a fluid/structure coupled analysis system for simulating complex flow-induced vibration (FIV) phenomenon of cascades has been developed. The flow is modeled using Euler and Wavier-Stokes equations with different turbulent models. The fluid domains are modeled using the unstructured grid system with dynamic deformations due to the motion of structural boundary. The Spalart-Allmaras (S-A) and the SST ${\kappa}-{\omega}$ turbulent models are used to predict the transonic turbulent flows. A fully implicit time marching scheme based on the Newmark direct integration method is used in order to solve the coupled governing equations for viscous flow-induced vibration phenomena. For the purpose of validation for the developed FIV analysis system, comparison results for computational analyses of steady and unsteady aerodynamics and flutter analyses are presented in the transonic flow region. In addition, flow-induced vibration analyses for the isolated cascade and multi-blades cascade models have been conducted to show the physical fluid-structure interaction effects in the time domain.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.793-802
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• 2006

In this study, a fluid/structure coupled analysis system for simulating complex flow-induced vibration (FIV) phenomenon of cascades has been developed. The flow is modeled using Euler and Wavier-Stokes equations with different turbulent models. The fluid domains are modeled using the unstructured grid system with dynamic deformations due to the motion of structural boundary. The Spalart-Allmaras (S-A) and the SST ${\kappa}-{\omega}$ turbulent models are used to predict the transonic turbulent flows. A fully implicit time marching scheme based on the Newmark direct integration method is used in order to solve the coupled governing equations for viscous flow-induced vibration phenomena. For the purpose of validation for the developed FIV analysis system, comparison results for computational analyses of steady and unsteady aerodynamics and flutter analyses are presented in the transonic flow region. In addition, flow-induced vibration analyses for the isolated cascade and multi-blades cascade models have been conducted to show the physical fluid-structure interaction effects in the time domain.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.34-40
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• 2019

We performed shape optimization of an anti-vibration rubber assembly which is used in the field option cabin of agricultural tractors to improve the vibration isolation capability. To characterize the hyper-elastic material property of rubber, we performed uniaxial and biaxial tension tests and used the data to calibrate the material model applied in the finite element analyses. We conducted a field test to characterize the input excitation from the tractor and the output response at the cabin frame. To account for the nonlinear behavior of rubber, we performed static analyses to derive the load-displacement curve of the anti-vibration rubber assembly. The stiffness of the rubber assembly could be calculated from this curve and was input to the harmonic analyses of the cabin. We compared the results with the test data for verification. We utilized Taguchi's parameter design method to determine the optimal shape of the anti-vibration rubber assembly and found two distinct shapes with reduced stiffness. Results show that the vibration at the cabin frame was reduced by approximately 35% or 47.6% compared with the initial design using the two optimized models.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.125-131
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• 2021

For the vibration reliability tests, the jigs for mounting the test specimen on a vibration reliability tester are required. The dynamic stabilities of the jigs should be verified before the tests for obtaining the accurate reliability of the test specimen. This paper proposes an analytical technology for ensuring the dynamic structural stability for the test setup including the jig. The technology includes the mode analyses for checking resonance, the harmonic analyses for evaluating the dynamic structural stability of test setup including the jig, and the fatigue analyses for obtaining the durable reliability time with calculating the life cycles at the area of weakness. The cause investigation of the damaged jig during vibration reliability test of a rubber hose and the design of new revised jig are performed by using the technology. The vibration reliability test for the rubber hose with the new revised jig by analysis results is successfully conducted without any problem. Therefore the jig's design technology proposed in this paper may be useful for other items as well.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.171-176
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• 2001

Recent building structures are superior in its ability but they are light and flexible, and so have problems of vibration. In general, the problem of vertical vibration is not considered in structural design. However, in terms of serviceability for inhabitants in buildings, the estimation of vibration in design stage is important. Characteristics of vertical vibration is changed by modeling method of beam-column joint. To check the characteristics of vertical vibration, many tests and analyses were conducted on constructing building in Seoul. Results of tests and analyses were compared using transfer function. As a results, to check the vertical vibration, the cramp ratio of beam-column joint must be considered and reduced in structural design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.948-954
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• 2002

The structural vibration of a diesel generator set was investigated through analyses and tests. FE modeling and normal mode analysis were performed and compared with measured results for both structure components and generator set assembly. The results of component analyses were fairly well coincident with measured results but those of assembled generator set showed more or less discrepancies. Discussions were given about the uncertainties for vibration characteristics of component structures and assembled running structures especially concerning their nonlinearities and damping effects. Detailed excitation analysis fellowed by forced response analysis was done from the engine and pressure data to compare with the actual measured vibration. As results the vibration prediction for frame structures of reciprocating internal combustion engine was confirmed reliable to some extent.