• Proceedings of the KSME Conference
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• 2000.04a
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• pp.608-612
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• 2000

Active control of sound radiation(using active structural acoustic control) from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Control structural input are achieved by two piezoceramic actuators bonded to the surface of the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The control approach are based on a multi-channel filtered-x LMS algorithm. The results demonstrate that attenuation of sound levels of 3dB, 13dB are achieved.

• Smart Structures and Systems
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• v.15 no.4
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• pp.963-995
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• 2015

The effectiveness of the various control algorithms for semi-active structural control systems proposed in the literature is highly questionable when dealing with earthquake actions, which never reach a steady state. From this perspective, the paper summarizes the results of an experimental activity aimed to compare the effectiveness of four different semi-active control algorithms on a structural mock up representative of a class of structural systems particularly prone to seismic actions. The controlled structure is a near full scale 2-story steel frame, equipped with two semi-active bracing systems including two magnetorheological dampers designed and manufactured in Europe. A set of earthquake records has been applied at the base of the structure, by utilizing a shaking table facility. Experimental results are compared in terms of displacements, absolute accelerations and energy dissipation capability. A further analysis on the percentage incidence of undesired and/or unpredictable operations corresponding to each algorithm gives an insight on some factors affecting the reliability and, in turn, the real effectiveness of semi-active structural control systems.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.74-80
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• 2013

This study describes structural reliability analysis of actively-controlled structure for which random vibration analysis is incorporated into the first-order reliability method (FORM) framework. The existing approaches perform the reliability analysis based on the RMS response, whereas the proposed study uses the peak response for the reliability analysis. Therefore, the proposed approach provides us a meaningful performance measure of the active control system, i.e., realistic failure probability. In addition, it can deal with the uncertainties in the system parameters as well as the excitations in single-loop reliability analysis, whereas the conventional random vibration analysis requires double-loop reliability analysis; one is for the system parameters and the other is for stochastic excitations. The effectiveness of the proposed approach is demonstrated through a numerical example where the proposed approach shows fast and accurate reliability (or inversely failure probability) assessment results of the dynamical active control system against random seismic excitations in the presence of parametric uncertainties of the dynamical structural system.

• Smart Structures and Systems
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• v.23 no.3
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• pp.243-261
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• 2019

This paper introduces an appropriate technique to estimate the weighting matrices used in the linear quadratic regulator (LQR) method for active structural control. For this purpose, a parameter is defined to regulate the relationship between the structural energy and control force. The optimum value of the regulating parameter, is determined for single degree of freedom (SDOF) systems under seismic excitations. In addition, the suggested technique is generalized for multiple degrees of freedom (MDOF) active control systems. Numerical examples demonstrate the robustness of the proposed method for controlled buildings under a wide range of seismic excitations.

• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.767-773
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• 2004

Semi-active control systems have attracted a great deal of attention in recent years, because they offer the adaptability of active devices without requiring large Power sources. One of the most Promising semi-active devices proposed for structural control is magneto-rheological fluid dampers (MR damper). In this paper, an MR damper having the capacity of about 1 ton was designed and fabricated. and series of tests were performed to grasp the fundamental Performance characteristics of it. It was also applied to a 6-story steel structure under random excitation and 3-different seismic excitations for the confirmation of its validity on structural vibration absorption. Through this study, the techniques and know-hows for MR damper production were acquired.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.4
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• pp.339-346
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• 2012

In this paper, equivalent models for active control devices are proposed so that building structures with such devices are analyzed using commercial structural analysis programs for the assessment of the structural members under active vibration control. Equivalent link models represent active control device with a virtual linear spring and dashpot, and equivalent force models are control force history acting at the installation point in structural models. Active controllers are designed based on the reduced-order models for a vertical cantilever model and a high-rise building model and corresponding equivalent models are determined from control gain matrices. Based on acceleration, displacement and member force responses, the effectiveness of the equivalent models is verified. As a result, proposed equivalent models, of which equivalent link model showed better performance, appear to enable detailed investigation of structural behavior to the extent of member force level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.431-435
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• 2001

The active structural control has emerged as structural safety of structures against natural loadings such as earthquake and wind loadings. Of many control algorithms, Sliding-Mode Control (SMC) can design both linear controller and nonlinear controller. The robustness against parameter variations as well as excitation uncertainties that is imparted to the SMC due to its nonlinear control action, could make SMC an attractive control algorithm when dealing with structures where the external excitation constitutes the main uncertainty in the system. This paper demonstrates experimentally the efficacy of the SMC algorithm based on the active mass driver system in reducing the response of seismically excited buildings. The SMC control strategy is verified with the experimental study on the one-story building model equipped with the active mass driver.

• Structural Engineering and Mechanics
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• v.39 no.1
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• pp.147-168
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• 2011

To ensure safety and long term performance, structural control has rapidly matured over the past decade into a viable means of limiting structural responses to strong winds and earthquakes. Nonlinear response history analysis requires rigorous procedure to compute seismic demands. Therefore the simplified nonlinear analysis procedures are useful to determine performance of the structure. In this investigation, application of improved capacity demand diagram method in the control of structural system is presented for the first time. Developed pole assignment method (DPAM) in structural systems control is introduced. Genetic algorithm (GA) is employed as an optimization tool for minimizing a target function that defines values of coefficient matrices providing the placement of actuators and optimal control forces. The ground acceleration is modified under induced control forces. Due to this, performance of structure based on improved nonlinear demand diagram is selected to threshold of nonlinear behavior of structure. With small energy consumption characteristics, semi-active devices are especially attractive solutions for limiting earthquake effects. To illustrate the efficiency of DPAM, a 30-story steel moment frame structure employing the semi-active control devices is applied. In comparison to the widely used linear quadratic regulation (LQR), the DPAM controller was shown to be just as effective and better in the reduction of structural responses during large earthquakes.

• Structural Engineering and Mechanics
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• v.4 no.2
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• pp.125-138
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• 1996

This paper deals with the application of certain active and passive control mechanisms to control the dynamic response of a steel jacket platform due to wave-induced forces. The forces are estimated using the nonlinear Morison equation which provides nonlinear self-excited hydrodynamic forces. The influence of these forces on the response of a structure without and with vibration control mechanisms is demonstrated using a steel jacket platform as a simple example.