• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.476-483
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• 2004

This paper presents a hybrid system combining lead rubber bearings and hydraulic actuators controlled by a μ-synthesis method for seismic response control of a cable-stayed bridge. A hybrid system could alleviate some of restrictions and limitations that exist when each system is acting alone because multiple control devices are operating. Therefore, the overall control performance of a hybrid system may be improved compared to each system, however the overall system robustness may be negatively impacted by active device in the hybrid system or active controller may cause instability due to small margins. Therefore, a f-synthesis method that guarantees the robust performance is considered to enhance the possibility of real applications of the control system. The control performances of the proposed control system are compared with those of passive, active, semiactive control systems and hybrid system controlled by LQG algorithm and an extensive robust analysis with respect to stiffness and mass matrices perturbation and time delay of actuator is performed. Numerical simulation results show that the control performance of the proposed control system is superior to that of the passive system and slightly better than that of the active and semiactive systems and two hybrid systems show similar control performances. Furthermore, the hybrid system controlled by a μ-synthesis method shows the good robustness without loss of control performances. Therefore, the proposed control system could effectively be used to seismically excited cable-stayed bridge which contains many uncertainties.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.193-200
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• 2003

This paper presents a hybrid (i.e., integrated passive-active) system for seismic response control of a cable-stayed bridge. Because multiple control devices are operating, a hybrid control system could alleviate some of the restrictions and limitations that exist when each system is acting alone. Lead rubber bearings are used as passive control devices to reduce the earthquake-induced forces in the bridge and hydraulic actuators are used as active control devices to further reduce the bridge responses, especially deck displacements. In the proposed hybrid control system, a linear quadratic Gaussian control algorithm is adopted as a primary controller. In addition, a secondary bang-bang type (i.e., on-off type) controller according to the responses of lead rubber bearings is considered to increase the controller robustness. Numerical simulation results show that control performances of the hybrid control system are superior to those of the passive control system and slightly better than those of the fully active control system. Furthermore, it is verified that the hybrid control system with a bang-bang type controller is more robust for stiffness perturbation than the active controller with μ-synthesis method and there are no signs of instability in the overall system whereas the active control system with linear quadratic Gaussian algorithm shows instabilities in the perturbed system. Therefore, the proposed hybrid protective system could effectively be used to seismically excited cable-stayed bridges.

• Structural Engineering and Mechanics
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• 제12권6호
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• pp.633-656
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• 2001

In this paper, modal control with direct output feedback is formulated in a systematic manner for easy implementation. Its application to the seismic protection of structural systems is verified by a shaking table test, which involves a full-scale building model and an active bracing system as the control device. Two modal control cases, namely, one full-state feedback and one direct output feedback control were tested and compared. The experimental result shows that in mitigating the seismic response of building structures, modal control with direct output feedback can be as effective and efficient as that with full-state feedback control. For practical concerns, the control performance of the proposed method in the presence of sensor noise and stiffness modeling error was also investigated. The numerical result shows that although the control force may be increased, the maximum floor displacements of the controlled structure are very insensitive to sensor noise and modeling error.

• 한국BIM학회 논문집
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• 제6권3호
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• pp.42-48
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• 2016

Structural members are designed to maintain the load-carrying capacity as well as structural strength, and the structural serviceability such as the deflection, cracks, and vibration to give the occupants uncomfortable environment should be checked. Recently, the importance of the vibration has been issued since the Techno Mart accident due to vibration resonance. This study provides a passive vibration control system using the repulsion force of magnets to reduce dynamic vibrations. The systems is devised by importing the constraint condition by a hinge to operate magnets installed at two adjacent locations. The effectiveness of the proposed system is investigated by the vibration control test of a steel beam with and without the control system. It is illustrated in the test that the system is activated by the control forces executed by the magnets and can be utilized in reducing the dynamic responses. The system can be applied to pedestrian bridge and traffic bridge. The applicability is expected in the future by optimizing the factors to affect the dynamic responses like the intensity, mass, locations of magnets.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.348-354
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• 2003

This study outlines the analysis of toggle system and the vibration control performance when the toggle-rotational inertia damper system was applied to a structure. Numerical analysis shows that the relative displacement of the structure can be amplified by amplification mechanism of the toggle system and the capacity of the damper can be reduced without the loss of vibration control performance. It is also observed that vibration control effects is caused by the increase of equivalent mass due to the rotational inertia of damper.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.423-430
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• 2004

A new active neuro-control strategy for seismic response reduction using modal states is proposed. In order to apply the neuro-control strategy to the given structural system it is needed to select state variables used as inputs into the neural network. If the degrees of freedom of the analytical model is large, there are so many possible combinations of the state variables. And selecting state variables is very complicated and troublesome task for the designer. In order to avoid this problem, the proposed control system adopts modal states as inputs. Since the modal states contain the information of the whole structural system's behavior, it is proper to use modal states as inputs of the neuro-controller. The simulation results show that the proposed the proposed active neuro-control strategy is quite effective to reduce seismic responses. In addition, the consuming time for training proposed neuro-controller is quite shorter than that for the conventional neuro- controller. The results of this investigation, therefore, indicate that the proposed active neuro-control strategy using modal states as the inputs could be effectively used for control seismically excited structures.

• Journal of Advanced Marine Engineering and Technology
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• 제38권10호
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• pp.1318-1326
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• 2014

The purpose of a tracking control system is to track a moving target and to find the exact information of the target. If the platform of the tracking control system is equipped on a moving vehicle such as a ship, the tracking control system will treat even the additional platform motion. In order to avoid the complexity comprising the tracking control system, a process to treat the platform motion, named stabilizing system, must be separated from the tracking control system. In this paper, a method to comprise an attitude control system for the platform stabilization is proposed using an adaptive fuzzy control which is applicable to the system with structural and parametric uncertainty. The suggested adaptive fuzzy control algorithm is the 2nd/1st-type indirect adaptive fuzzy control algorithm using the advantages of 1st-type and 2nd-type indirect adaptive fuzzy control algorithm. Several experiments using the implemented stabilizing system are executed for verifying the effectiveness of the suggested method.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.210-215
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• 2008

This study presents an effective stiffness-based optimal technique to control quantitatively lateral drift and evaluates the structural behavior characteristics and efficiency for tall outrigger system subject to lateral loads. To this end, displacement sensitivity depending on behavior characteristics of outrigger system is established and approximation concept that can efficiently solve large scale problems is introduced. Specifically, under the 'constant-shape' assumption, resizing technique of member is developed. Two types of 60 story frameworks are presented to illustrate the features of the quantitative lateral drift control technique proposed in this study.

• 대한조선학회논문집
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• 제32권1호
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• pp.94-102
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• 1995

유압식 actuator를 이용한 구조물 진동의 능동제어시스템을 개발하였다. 개발한 시스템은 유압장치, actuator 및 제어장치로 구성되어 있으며, 구조물의 진동을 수진기로 감지하고, 이 신호를 받아 actuator에 연결된 보조질량의 운동을 최적제어하여 구조물의 진동을 제어한다. 능동제어시스템의 제어성능 검증시험을 위해 약 500kg의 4기둥지지 후판구조물($L{\times}W{$\times}H=1200mm{\times}800mm{\times}1600mm$)을 제작하여 시험을 수행하였으며, 시험결과 구조물의 공진주파수 근처에서 진동레벨이 약 1/6수준으로 감소됨을 확인하였다.

• Structural Engineering and Mechanics
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• 제82권4호
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• pp.445-458
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• 2022

Some of the control systems used in engineering structures that use sensors and decision systems have some time delay reducing efficiency of the control system or even might make it unstable. In this research, in addition to considering the effect of the time delay in vibration control process, predictive control is used to compensate the time delay. A semi-active vibration control approach with the help of magneto-rheological dampers is implemented. In addition to using fuzzy inference system to determine the appropriate control voltage for MR damper, structural behavior prediction system and specifying future responses are also used such that the time delays occurring within control process are overcome. For this purpose, determination of prediction horizon is conducted for one, five, and ten steps ahead for single degree of freedom structures with periods ranging from 0.1 to 4 seconds, subjected to twenty earthquake excitations. The amount of time delay applied to the control system is 0.1 seconds. The obtained results indicate that for 0.1 second time delay, average prediction error values compared to the case without time delay is 3.47 percent. Having 0.1 second time delay in a semi-active control system reduces its efficiency by 11.46 percent; while after providing the control system with structure behavior prediction, the difference in the results for the control system without time delay is just 1.35 percent on average; indicating a 10.11 percent performance improvement for the control system.