• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.926-939
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• 2022

The area of this study will cover the location-wise seismic response variation of an electrical cabinet in nuclear power point (NPP) based on classical reliability analysis. The location-based seismic ground motion (GM) selection is carried out with the help of probabilistic seismic hazard analysis using PSHRisktool, where the variation of reliability analysis can be understood from the relation between the reliability index and intensity measure. Two different approaches such as the first-order second moment method (FOSM) and Monte Carlo Simulation (MCS) are helped to evaluate and compare the reliability assessment of the cabinet. The cabinet is modeled with material uncertainty utilizing Steel01 as the material model and the fiber section modeling approach is considered to characterize the section's nonlinear reaction behavior. To verify the modal frequency, this study compares the FEM result with recorded data using Least-Squares Complex Exponential (LSCE) method from the impact hammer test. In spite of a few investigations, the main novelty of this study is to introduce the reader to check and compare the seismic reliability assessment variation in different seismic locations and for different earthquake levels. Alongside, the betterment can be found by comparing the result between two considered reliability estimation methods.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.73-80
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• 2006

In order to compute the radiated sound from a vibrating structure, the Rayleigh's integral equation has to be derived from the Helmholtz equation using Green's function. Generally, the surface velocity in the Rayleigh's integral equation uses the root mean square(rms) velocity. The calculation value is too large, because it's not considered cancelation. On the other hand. using the complex velocity, the sound pressure is calculated too small, because it considers that sound is perfectly canceled out. Therefore, this thesis proposes a correction factor(CF) which considers vibration modes and the method by which to calculate the radiating sound pressure. The theoretical results are compared with the experimental values, and the proposed method can be verified with confluence.

• Journal of KSNVE
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• v.11 no.3
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• pp.416-421
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• 2001

The flexural vibration of laminated composite beams with an electro-rheological(ER) fluid has been investigated to design a structure with maximum possible damping capacity. The equations of motion are derived for flexural vibrations of symmetrical, mu1ti-layer laminated beams. The damping radio and modal damping of the first bending mode are calculated by means of iterative complex eigensolution method. Finite element method is used for the analysis of dynamic characteristics of the laminated composite beams with an ER fluid. For the validation of modeling methodology using viscoelastic theory the predicted dynamic properties are compared to the measured ones by author's previous work. They are in good agreement. This paper addresses a design strategy of laminated composite under flexural vibrations with an ER fluid.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.903-912
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• 2007

One of the crucial factors which determine the quality and the accuracy of SEA model is how subsystems are defined. Experimental SEA technique had been a unique way to divide entire systems accurately for mid-frequency range, until FEA based virtual FRF response technique, virtual SEA method presented. Virtaul SEA has been developed for predictive SEA tool in early design process. In this study, Modal analysis results from modified crash FE model is used for Statistical transfer matrix. Observation nodes on the cockpit are grouped by attractive substructuring method based on point to point transfer and correlation matrix. Complex cockpit structure is divided into subsystems by automatic substructuring. Comparison with experimental SEA results validates the application of Virtual SEA to cockpit.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.379-382
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• 2007

The proper orthogonal decomposition(POD) is used to the modal analysis of microcantilever of dynamic mode atomic force microscopy(AFM). The proper orthogonal modes(POM) are extracted from vibrating signals of microcantilever when it resonates and taps the sample. The POMs resemble the linear normal modes(LNM) of cantilever vibrating at each resonance frequency. Some of POMs in tapping microcantilever show quite different shapes from the POMs of the resonating microcantilever. Also this POMs can be applied to model for the complex nonlinear behavior of the dynamic mode AFM microcantilevers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.12
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• pp.1206-1212
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• 2012

The brake squeal propensity due to the friction-velocity curve is numerically investigated. The finite element models for the disc and pad are correlated with the modal test. In the friction-engaged system modeling, the friction function is linearized at the equilibrium. The damping term induced by friction-velocity slope is incorporated into the equations of motion. In the complex eigenvalue analysis, it is found that the pad shear mode is very sensitive to the friction curve. The results shows that the squeal propensity of the pad shear mode can be controlled by the design parameters such as pressure and stiffness.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.127-132
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• 2010

Eigensolutions associated with self-excited vibration of disc brake system can be obtained by complex eigenvalue analysis. The eigenvalue sensitivity to change in contact stiffness can be used to demonstrate stability criteria and eigenvalue veering. Dynamic instability on eigenvalue loci with respect to the variation of contact stiffness is found to be related to mode interaction between two adjacent modes. This modal interaction can be effectively shown by mode shape visualization. This paper presents the methodology to construct the mode shape of disc brake system where a disc and two brake pads are coupled with contact stiffness.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.149-159
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• 2004

Dynamic analysis of laminated beams with a embedded damping layer under tensional and compressive axial load is investigated. Improved Layer-Wise Zig-Zag Beam Theory and Interdependent Kinematic Relation are incorporated to model the laminated beams with a damping layer and a corresponding beam zig-zag finite element is developed. Flexural frequencies and modal loss factors under tension or compression axial load are calculated based on Complex Eigenvalue Method. The effects of the axial tensional and compressive load on the frequencies and loss factors are discussed.

• Journal of KSNVE
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• v.8 no.4
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• pp.690-699
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• 1998

This paper discusses the techniques, procedures and the results of the ground vibration test(GVT) performed on the development aircraft and the simple procedure of FE model updating technique from the GVT results. The GVT was carried out using random excitation technique with MIMO(Multi-Input-Multi-Output) data acquistion method, and taking full advantage of poly-reference global parameter estimation technique to identify the vibration modes. In dynamic FE modeling, the aircraft was represented by beam elements and all dynamic analysis was performed using MSC/NASTRAN for this model. In updating procedure, the stiffness of the beam model was adjusted iteratively so as to get the natural frequencies and mode shapes close to the GVT results.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.149-156
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• 2004

In this study, vibration and aeroelastic analyses of a T-tail have been conducted. The structural dynamic computations of the T-tail are performed using MSC/NASTRAN and CFD-based computational aeroelastic analysis method is used to investigate the complex flutter phenomena. The results for vibration and aeroelastic analyses in the frequency and time domains are presented. It is importantly shown that the modal coupling of the torsional mode of vertical-wing and the asymmetric bending mode of horizontal-wing parts can give sensitive effects for the flutter stability of T-tail configurations.