• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.291-293
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• 2012

AMD 능동형 제진장치를 이용하여 플로팅 구조물을 제어하기 위해서는 수조실험을 통해 플로팅 함체 구조물의 롤링방향에 대한 동적 특성을 추정한 후 대상 구조물 특성에 적합한 제어알고리즘을 적용하여 수치시뮬레이션을 통한 제어의 가능성 확인 및 향후 실제 제진장치를 설치하여 검증실험을 통해 플로팅 구조물 능동제어의 효과를 검증해야 한다.

• Journal of KSNVE
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• v.16 no.6 s.84
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• pp.36-41
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• 2006

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.801-811
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• 1998

In this paper, aerodynamic properties and improvements of the ${\pi}-shaped$ stiffening girder is studied by wind tunnel tests in steel composite cable stayed bridge. As an improvement device, fairing, extension, post and flap is tested. and the best improved section is selected and estimated on angles of attack, damping ratios and turbulent flows. It is shown that the selected fairing is effective to improve the aerodynamic stability. And this study can be utilized as a database of wind-resistant methodology of steel composite cable stayed bridge.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.656-661
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• 2005

An optimization formulation of unconstrained damping treatment on beams is proposed to minimize vibration responses using a numerical search method. The fractional derivative model is combined with RUK's equivalent stiffness approach in order to represent nonlinearity of complex modulus of damping materials with frequency and temperature. The loss factors of partially covered unconstrained beam are calculated by the modal strain energy method. Vibration responses are calculated by using the modal superposition method, and of which design sensitivity formula with respect to damping layout is derived analytically. Plugging the sensitivity formula into optimization software, we can determine optimally damping treatment region that gives minimum forced response under a given boundary condition. A numerical example shows that the proposed method is very effective in minimizing vibration responses with unconstrained damping layer treatment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.7 s.100
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• pp.829-835
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• 2005

An optimization formulation of unconstrained damping treatment on beam is proposed to minimize vibration responses using a numerical search method. The fractional derivative model is combined with RUK's equivalent stiffness approach in order to represent nonlinearity of complex modulus of damping materials with frequency and temperature. Vibration responses are calculated by using the modal superposition principle, and of which design sensitivity formula with respect to damping layout is derived analytically. Plugging the sensitivity formula into optimization software, we can determine optimally damping treatment region that gives minimum forced response under a given boundary condition. A numerical example shows that the proposed method is very effective in suppressing nitration responses by means of unconstrained damping layer treatment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.12
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• pp.938-946
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• 2003

Length of an unconstrained viscoelastic damping layer on beams is determined to maximizeloss factor using a numerical search method. The fractional derivative model can describe damping characteristics of viscoelastic damping materials accurately, and is used to represent nonlinearity of complex modulus with frequencies and temperatures. Equivalent flexural rigidity of the unconstrained beam is obtained using Ross, Ungar, Kelvin[RUK] equation. The loss factors of partially covered unconstrained beam are calculated by a modal strain energy method. Optimal lengths of the unconstrained viscoelastic damping layer of beams are identified with ambient temperatures and thickness ratios of beam and damping layer by using a finite-difference-based steepest descent method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.665-671
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• 2003

Length of an unconstrained viscoelastic damping layer on beams is determined to maximize loss factor using a numerical search method. The fractional derivative model can describe damping characteristics of the viscoelastic damping material, and is used to represent nonlinearity of complex modulus with frequencies and temperatures. Equivalent flexural rigidity of the unconstrained beam is obtained using Ross, Ungar, Kerwin(RUK) equation. The loss factors of partially covered unconstrained beam are calculated by a modal strain energy method. Optimal lengths of the unconstrained viscoelastic damping layer of beams are obtained with respect to ambient temperatures and thickness ratios of beam and damping layer.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.138-146
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• 2002

The new type of vibration reduction material far an automotive interior, which is spray-type liquid material, is developed in this study The new material has better damping property and lower mass density than other damping materials, for example asphalt sheet. It can be sprayed by an automatic robot, so it is expected to improve productivity and cut down manpower. And it solves a poor adhesion problem and makes an automotive to be lightweight by optimizing spray process. So, It is a next generation automotive vibration reduction material. In this paper, the chemical process for making the new damping materials is described. And then, the damping properties of the vibration reduction materials are analyzed by modal testing of damping treatment specimens. The new vibration reduction materials have good damping properties than asphalt sheet in the experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.55-62
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• 2004

In general, control performance of the active control system is superior to that of the passive control devices. However, the active system require a large amount of external energy to operate the actuators. Semi-active control systems maintain the reliability of the passive control systems while taking advantage of the adjustability of the active control system. In this research, a semi-active orificed fluid damper having the capacity of about 2 tons was designed and fabricated. It is a two-stage damper with normally open solenoid valve. A series of tests was performed to grasp its performance characteristics. It was also applied to a 6-story steel structure subjected to random and seismic excitations for the confirmation of its validity on structural vibration absorption.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.37-48
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• 2010

The seismic control effect of reinforced concrete structures with low energy dissipating capacity due to stiffness degradation is investigated through nonlinear time history analysis. The primary structure is idealized as a SDOF system of modified Takeda hysteresis rule and an elasto-perfectly-plastic nonlinear spring is added to represent a hysteretic damping device. Based on statistics of the numerical analysis, equivalent linearization techniques are evaluated, and empirical equations for response prediction are proposed. As a result, estimation of the ductility demand with proposed empirical equations is more desirable than the equivalent linearization techniques. The optimal yield strengths based on empirical equations are significantly different from the optimal yield strength of elasto-perfectly-plastic systems. Also, the results indicate that the reduction effect of the ductility demand is more remarkable for smaller natural periods.