• Proceeding of KASS Symposium
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• 2008.05a
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• pp.74-79
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• 2008

In this study, impact transient responses of (Graphite/Epoxy) laminated composite subjected to low-velocity impact are investigated using a finite element method. Dynamic von-Karman plate equations considering large deflection of plate are modified to include the effect of transverse shear deformations as in Mindlin plate theory and also the rotary inertia effect is considered. The convergence of transient responses is used contact law established through the statical indentation test. We investigate displacements, contact forces and strains by thickness variation of various laminated composite. We compare and analyze each results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.597-604
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• 1994

In this paper, the "Stop-and-GO" algorithm is applied to the PRS(Partial Response Signal) type signaling. Stop-and-GO blind equalizer has a property of stopping the adaptation of its tab coefficients by means of a simples flag telling the equalizer whether the current output error with respect to decided symbol is sufficiently reliable to be used. PRS has the rule os level transition, which makes it possible that the level of currently received symbol is in the adjacent levels of the previously received symbol. New nonlinear estimators for PRS, based on the rule of level transition, is proposed. The computer simulation results show the improvement in performance achievable with proposed nonlinear estimators.stimators.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.29-40
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• 2013

Seismic response of single degree of freedom system supported by shallow foundation was analyzed by using nonlinear explicit finite difference element code. Numerical analysis results were verified with dynamic centrifuge test results of the same soil profile and structural dimensions with the numerical analysis model at a centrifugal acceleration of 20 g. Differences between the analysis and the test results induced by the boundary conditions of control points can be reduced by adding additional local damping to the natural born cyclic hysteretic damping of the soil strata. The analysis results show good agreement with the test results in terms of both time histories and response spectra. Thus, it can be concluded that the nonlinear explicit finite difference element code will be a useful technique for estimating seismic residual displacement, earthpressure etc. which are difficult to measure during laboratory tests and real earthquake.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.5
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• pp.33-39
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• 2010

This study develops an approximate procedure for incremental dynamic analysis (IDA) using modal pushover analysis (MPA) with empirical equations of the inelastic displacement ratio ($C_R$) and the collapse strength ratio ($R_C$). By using this procedure, it is not required to conduct linear or nonlinear response history analyses of multi- or single- degree of freedom (MDF) systems. Thus, IDA curves can be effortlessly obtained. For verification of the proposed procedure, the 6-, 9- and 20-story steel moment frames are tested under an ensemble of 44 ground motions. The results show that the MPA-based IDA with empirical equations of $C_R$ and $R_C$ produced accurate IDA curves of the MDF systems. The computing time is almost negligible compared to the exact IDA using repeated nonlinear response history analysis (RHA) of a structure and the original MPA-based IDA using repeated nonlinear RHA of modal SDF systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.36-41
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• 2016

In this study, numerical analyses were used to investigate the performance of a coupling control method for the dynamic responses of adjacent buildings under multiple hazards. Numerical simulations were done using the earthquake loads of regions with strong seismicity in Los Angeles, California, and the wind loads in regions with strong winds in Charleston, North Carolina. The artificial earthquake and wind loads were made using SIMQKE and Kaimal Spectrum based on ASCE 7-10. Ten-story and twenty-story adjacent buildings were selected as example structures, and nonlinear hysteretic dampers were used to connect them. The Bouc-Wen model was used to model the nonlinear hysteretic dampers. The results show that the proposed control method could effectively reduce the dynamic responses, and the optimal control designs were different for each hazard.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.2
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• pp.133-141
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• 2024

Considering fluid-structure-soil interactions, a finite-element model for a liquid-storage tank is presented and the nonlinear earthquake response analysis is formulated. The tank structure is modeled considering shell elements with geometric and material nonlinearities. The fluid is represented by acoustic elements and combined with the structure using interface elements. To consider the soil-structure interactions, the near- and far-field regions of soil are modeled with solid elements and perfectly matched discrete layers, respectively. This approach is applied to the seismic fragility analysis of a 200,000 kL liquid-storage tank. The fragility curve is observed to be influenced by the amplification and filtering of rock outcrop motions at the site when the soil-structure interactions are considered.

• Proceedings of the Korean Fiber Society Conference
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• 1994.10a
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• pp.100-101
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• 1994

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.435-443
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• 2010

This study presents key parameters for the structure installed with MR controller in reducing its responses. MR controller is regarded as Bingham model of which control forces are frictional and viscous ones. The parameters are identified as friction force ratios, $R_f$ and $R_h$ which are, respectively, ratio of MR controller friction force to static restoring force for free vibration and ratio of the friction force to amplitude of harmonic force. Structure-MR controller system shows nonlinear response behavior due to friction force. Energy balance strategy is adopted to transform the behavior to linear one with equivalent damping ratio. Finally, proposed equivalent linear process is compared to the nonlinear one, which turns out to give acceptably good results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.377-388
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• 2016

This study is aimed to evaluate the embedment effect of foundation as compared to the surface foundation on the response of a base-isolated nuclear power plant structure. For this purpose, the boundary reaction method (BRM), which is a two-step frequency domain and time domain technique, is used for the nonlinear SSI analysis considering nonlinear behavior of base isolators. The numerical model of the BRM is verified by comparing the numerical results obtained by the BRM and the conventional frequency-domain SSI analysis for an equivalent linear SSI system. Finally, the displacement response of the base isolation and the horizontal response of the structure obtained by the nonlinear SSI analysis using the moat foundation model are compared with those using the surface foundation model. The comparison showed that the displacement response of the base isolation can be reduced by considering the embedment effect of foundation.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.637-647
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• 1997

As stated in Part(I), the use of the isolator is meant to protect a structure from seismic risk, by concentrating the inelastic deformations to relatively cheap and replaceable devices while the rest of the structures remains elastic. This research has been carried out to investigate the effects of various structural parameters and isolator characteristics on the seismic response of Base Isolated Bridges. Simplified analysis method for practical design is developed by using the results. The Proposed Code-Type approach method can be used to estimate the inertial forces accurately, not only at the isolator but throughout the height of the Base-Isolated Bridges. The proposed method is recommended to use in preliminary design tool or even a final design tool for Base Isolated Bridges. For the validation of simplified design method, examples with artificial earthquake time history and design response spectrum for P.C Box Bridge with bilinear hysteretic steel damper are evaluated.