• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.292-298
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• 2009

This paper investigates the control performance of the proposed hybrid mount system for vibration isolation table. The hybrid mount system consists of an air spring as a passive device and a PZT stack actuator as an active device in series. The feasibility of the PZT stack actuator as an active actuator was examined through the simple experiments. After that, a series of numerical simulations were carried out to evaluate the control performance of the proposed hybrid mount system. The equations of motion of the table with a set of hybrid mount systems consisting of four devices are derived. The air spring is considered as a 1 spring and 1 dashpot elements, and PID control algorithm is adopted to estimate the control force. The results of the numerical simulations presents that the proposed hybrid mount system could be the promising control system for vibration isolation table.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.184-189
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• 2006

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by rising experiment and simulation. Optimal design for a passive air spring can be obtained by fluting the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the act ive vibration isolation table wi th the bet ter isolation performance.

• Earthquakes and Structures
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• v.27 no.1
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• pp.57-67
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• 2024

To assess the seismic performance of Plate-Shell Integrated Concrete Liquid-Storage Structure (PSICLSS), a scaled test model was constructed. This model incorporated a hybrid isolation system, which combined shape memory alloy (SMA), lead-cored rubber isolation bearing (LRB) and sliding isolation bearing (SB). By conducting shaking table test, the dynamic responses of both non-isolated and hybrid-isolated PSICLSS were analyzed. The results show that the hybrid isolation system can effectively reduce the acceleration and displacement responses of the structure. However, it also results in an increase in local hydrodynamic pressure and liquid sloshing height. Under extreme earthquake action, the displacement of isolation layer is small. When vertical ground motion is taken into account, the shock absorption rate of horizontal acceleration decreases. The peak hydrodynamic pressure increases significantly, and the peak hydrodynamic pressure position also changes. The maximum displacement of isolation layer increases, the residual displacement decreases.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.417-423
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• 2006

The seismic characteristics with 3-Dimensional isolation systems have been studied using a shaking table system. In this study, we made nuclear power plant main control room floor systems and several seismic shaking table tests with and without isolation systems were conducted to evaluate floor isolation effectiveness. Isolation systems have showed large reduction effectiveness in acceleration and response spectra with x and z direction respectively, but horizontal isolation is more effective than vertical one It is required to make isolation systems of which design frequency is below 1Hz when applied to main control room of NPP, but considering much difficulties in making such isolation systems, it is recommended that much consideration should be taken into account when applied to main control room of NPP.

• Structural Engineering and Mechanics
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• v.28 no.6
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• pp.677-694
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• 2008

A vibration power minimization model is developed, based on the mobility matrix method, for a vibration isolation system consisting of a vibrating source placed on an elastic support structure through multiple resilient mounts. This model is applied to investigate the design optimization of an X-Y motion stage-based vibration isolation system used in semiconductor wire-bonding equipment. By varying the stiffness coefficients of the resilient mounts while constraining the dynamic displacement amplitudes of the X-Y motion stage, the total power flow from the X-Y motion stage (the vibrating source) to the equipment table (the elastic support structure) is minimized at each frequency interval in the concerned frequency range for different stiffnesses of the equipment table. The results show that when the equipment table is relatively flexible, the optimal design based on the proposed vibration power inimization model gives significantly little power flow than that obtained using a conventional vibration force minimization model at some critical frequencies. When the equipment table is rigid enough, both models provide almost the same predictions on the total power flow.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.3
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• pp.125-135
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• 2017

Various seismic isolation methods are being applied to bridges and buildings to improve their seismic performance. Most seismic isolation systems are the structural seismic isolation systems. In this study, the seismic performance of geotechnical seismic isolation system capable of isolating the lower foundation of the bridge structure from ground was evaluated. The geotechnical seismic isolation system was built with teflon, and the model structure was made by adopting the similitude law. The response acceleration for sinusoidal waves of various amplitudes and frequencies and seismic waves were analyzed by performing 1-G shaking table experiments. Fixed foundation, Sliding foundation, and Rocking foundation were evaluated. The results of this study indicated that the Teflon-type seismic foundation isolation system is effective in reducing the acceleration transmitted to the superstructure subject to large input ground motion. Response spectrum of the Rocking and Sliding foundation structures moves to the long period, while that of Fixed foundation moves to short period.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.331-338
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• 2001

Seismic performances of the base isolated model of Five Story Stone Pagoda were studied through shaking table tests. Friction pendulum system (FPS), Pure-friction system with laminated rubber bearing (LRB) and Ball with rubber bearing were selected fur the comparison of performances. Performances of specially designed isolation systems were tested dynamically using shaking table. The test results of isolated model are compared with those of fixed base model. Compared with fixed base model, the isolated model showed that it could withstand much higer intensity of earthquake motion. The Effective Peak Ground Acceleration (EPGA) value of isolated model when the top component tipped over was above twice of that value in case of fixed base model. According to the additional test results, the lower value of coefficient of friction than that of common frictional base isolation systems is more effective to protect the piled multi-block system of Pagoda against moderate intesity of ground motion.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.409-416
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• 2006

The seismic characteristics with 3-Dimensional Floor Isolation System have been studied using a shaking table system. In this study, we made two kind of floor system (Type I, Type II) and several seismic tests with and without isolation system were conducted to evaluate 3-Dimensional Floor Isolation Effectiveness. Both type have showed large reduction effectiveness in acceleration, response spectra but Type II have showed lower acceleration and lower first mode in response spectra, compared to type I. On the basis of test results and consideration of application, it is found that type II is more suitable for floor model of main control room of Nuclear Power Plant.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.411-418
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• 2003

This paper presents the results of experimental studies on the equipment isolation effect in the nuclear containment. for this Purpose, shaking table tests were performed. The natural rubber bearing (NRB) and high damping rubber bearing (HDRB) were selected for the isolation. Peak ground acceleration, damping characteristics of isolation system and frequency contents of selected earthquake motions were considered. finally, it is presented that the NRB and HDRB systems are effective for the small equipment isolation and the damping of isolation systems can be affected to the seismic isolation effect.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.3 s.55
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• pp.33-42
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• 2007

In this study, for research on an improvement of the seismic safety of an EDG system, a small scale EDG system was manufactured. For the isolation system, the Coil Spring-Viscous Damper systems were selected. For the shaking table test, 3 kinds of seismic motions were selected which had different frequency contents. In this study, the isolation effects were different and they depended on the input seismic motion. In the case of an NRC earthquake which had low fiequency contents, the isolation effects of the horizontal direction were 20%. But for the seismic motions which had high fiequency contents, the isolation effects were $50{\sim}70%$. In the case of the vertical direction, poor isolation effects were observed. It was because the design properties and the real properties of the isolation system were a little different.