• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.55-66
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• 2004

Recently, many high-rise apartment buildings using the box system, composed of only reinforced concrete walls and slabs, have been constructed. In residential buildings such as apartments, vibrations occur from various sources and these vibrations transfer to neighboring residential units through walls and slabs. It is necessary to use a refined finite element model for an accurate vibration analysis of shear wall building structures. But it would take significant amount of computational time and memory if the entire building structure were subdivided into a finer mesh. Therefore, an efficient analytical method, which has only translational DOFs perpendicular to walls or slabs by the matrix condensation technique, is proposed in this study to obtain accurate results in significantly reduced computational time. If all of the DOFs except those perpendicular to walls or slabs in the shear wall structure eliminated using the matrix condensation technique at a time, the computational time for the matrix condensation would be significant. Thus, the modeling technique using super elements and substructuring technique is proposed to reduce the computational time for the matrix condensation. Dynamic analysis of 3-story and 5-story shear wall example structures were performed to verify the efficiency and accuracy of the proposed method. It was confirmed that the proposed method can provide the results with outstanding accuracy requiring significantly reduced computational time and memory.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.61-68
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• 2006

In this thesis, a full-scale K shape damper test model was constructed in which a passive vibration control system. This passive vibration control system was incorporated with the use of a newly developed turbulent flow damper sealed by viscoelastic material. A series of tests and earthquake observation has been conducted in this test model. The purpose of the present thesis is to investigate the vibration response characteristics of the building and to verify the effectiveness of the vibration control system. By the static loading test, it was recognized that incorporation of the dampers had little influence on static horizontal stiffness of the building. Free vibration tests revealed that the dampers incorporated increased the damping ratio of the building up to 3 times compared with the undamped case. The effectiveness of the developed vibration control system was confirmed based on the excitation tests and earthquake response observation.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.94-101
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• 1994

About vibration model of Six-degrees-of-freedom(DOF), in mass load, examined results for knowing dynamic interference and response variation is as follows; In case of putting mass load upon the object, experimented results on two-degrees-of-freedom of the translation-1 direction and the rotation-1 direction at open-loop-control system, about 0.19 arcsed in input of the translation-$0.1{\mu}m$ and $0.022{\mu}m$ on input of the rotation-0.5 arcsec, the justicse of motion equation is acknowledged as confirming the appearance of the interference-$0.022{\mu}m$. In establishing calculation of transformation matrix by using analogue circuit, as simulating results that used incomplete differentiation, interference is $1.7{\times}10^{-3}$ arcsec on input of the translation-$0.1{\mu}m$ and $1.4{\times}10^{4}{\mu}m$ on input of the rotation-0.5 arcsec in open-loop-control system. Also it is $4.2{\times}10^{-4}$ arcsec on input of the translation-$0.1{\mu}m$ and $5.6{\times}10^{-5}{\mu}m$ on input of the rotation-0.5 arcesc in closed-loop-control system. As closed-loop-control system is better than open-loop-control system, equivalent accordance is confirmed on original response. Finally, fundamental validity of this theory is acknowledged.

• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.131-135
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• 2004

Landing gear force reaction module is important for aircraft take off and landing simulation. But usually this modulo is not accounted for control law design simulation. because it does not affect the flying quality of aircraft. Now a days, this module is getting more important according to the increase of needs for training purpose simulation and specific control law design such as unmaned aircraft landing on the moving platform. In this paper 1DOF mass spring simple force system per gear was accepted.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.635-644
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• 2012

In order to design a wave energy generating system, a 6-DOF analysis technique is applied to the three-Dimensional CFD analysis on of a floating body and the behavior is interpreted according to the nature of the incoming wave. A wave period of 5.5s & amplitude of 0.57m from Marado is chosen. 12 case of natural pitching period from 1.25 to 2.8s has been modeled. The relation between tuning factor & pitch angle for the waves generated is compared to analyze the effects of energy absorption variables, namely mass moment of inertia, angular velocity and angular acceleration. From the results obtained, we conclude that model L is the maximum power absorbed, 6kW approximately. A maximum pitch angle of 1.91 degree was attained by Model F, and the maximum displacement of nearly 0.7m was attained by Model L among models D, F and L.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.147-154
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• 2014

The cable damages of the bridge structures induce very important impact on the structural safety, which implies the close monitoring of the cable damage is required to secure sustained safety of the bridges. Most usual available maintenance techniques are based on the monitoring the change of the natural frequency of the structures by damages. However, existing method are based on vibration method to calculate lateral vibration and system identification can calculate the axial stiffness using sensitivity equation by trial error method. But the frequency study by the longitudinal movement need because of the sag effect in system identification. This study proposes a new method to investigate the damage magnitudes and status. The method improves the accuracies in the magnitudes and status of damages by adopting the natural frequency of longitudinal movement. The study results have been validated by comparing them with the approximate solution of FEM. Thus, the relationship of cable damage and frequency appear with relation that the severe damage has the little frequency. If we know the real frequency we can estimate the cable damage severity using this relationship. This method can be possible the efficient management of the cable damage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1A
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• pp.31-43
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• 2009

In this study, the numerical method is presented, which can consider the various train types and can solve the equations of motion for a vehicle-bridge interaction analysis by non-iteration procedure through formulating the coupled equations of motion. The coupled equations of motion for the vehicle-bridge interaction are solved by the Newmark ${\beta}$ of a direct integration method, and by composing the effective stiffness matrix and the effective force vector according to a analysis step, those can be solved with the same manner of the solving procedure of equilibrium equations in static analysis. Also, the effective stiffness matrix is reconstructed by the Skyline method for increasing the analysis effectiveness. The Cholesky's matrix decomposition scheme is applied to the analysis procedure for minimizing the numerical errors that can be generated in directly calculating the inverse matrix. The equations of motion for the conventional trains are derived, and the numerical models of the conventional trains are idealized by a set of linear springs and dashpots with 16 degrees of freedom. The bridge models are simplified by the 3 dimensional space frame element which is based on the Euler-Bernoulli theory. The rail irregularities of vertical and lateral directions are generated by the PSD functions of the Federal Railroad Administration (FRA). The results of the vehicle-bridge interaction analysis are verified by the experimental results for the railway plate girder bridges of a span length with 12 m, 18 m, and the experimental and analytical data are applied to the low pass filtering scheme, and the basis frequency of the filtering is a 2 times of the 1st fundamental frequency of a bridge bending.