• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.107-114
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• 2008

The aim of this study is to obtain the useful design guideline for high impulsive force device with an isolation system by the analytic approach of dynamics characteristics. In this study, the high impulsive force system was modeled and analyzed in view of multi-body dynamics, and verified the modeling and analysis result by the experiment of the high impulsive force device. Additionally, the dynamic analysis was performed for the isolation system with the selected coefficients of elastic spring and damper selected. Experimental result for the high impulsive force device with the isolation system was compared and analyzed. From the result, it was confirmed that the design guideline for the isolation system of the high impulsive force device was useful.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.586-594
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• 1999

To limit both the large displacement and acceleration response of the structure efficiently, the relationships between acceleration and displacement responses of the structure under several earthquakes are investigated for various horizontal stiffness of the base isolation system to determine the effective stiffness of the base isolation system in this paper. An example structure is a five-storey steel frame building as the primary structure and the secondary structures are assumed to be located on the fifth floor of the primary structure. Input motions used in the structural analysis are El Centre 1940, Taft 1952, Mexico 1985, San Fernando 1971 Pacoima Dam, and artificially generated earthquakes. The relationships of the absolute peak acceleration and the displacement at the top of the structure are calculated for various natural periods of base isolators under various earthquakes. The peak acceleration response of the fifth floor in the base isolated structure is significantly reduced by a factor of 2.1 through 6.25. Also, the relative displacement response of the floor to the base of the superstructure is very small. The results of this study can be utilized to determine the effective stiffness of the base isolation system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.550-555
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• 2004

Fault section isolation and service restoration are very important for function of DAS. In Japan, a progressive protection method is used for the line to ground fault section isolation and service restoration. But the progressive protection method has a drawback that the customer will experience outage time and that the rate in use of the feeder is not over 50%. This paper presents a new Service Restoration Algorithm which is for the line to ground fault section isolation and service restoration method for a ungrounded distribution system. If the proposed algorithm is used, the rate in use of the feeder can improve than before because a distribution system can change multi connection of feeder and the customer's outage time can be reduced. The proposed algorithm has been successfully tested in a distribution system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1026-1031
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• 2003

A vibration isolation system fur a large reverberation chamber (1,228㎥, 1,000ton) has been installed. The reverberation chamber generates loud noise and induces high level of vibration to perform spacecraft acoustic environmental tests. The isolation system prevents vibration transfer from the chamber to enclosure buildings. This paper describes logical design process and commissioning experiments of the system. Design criteria have been induced from rigid body model of the chamber. Finite element model has been employed to select the characteristics of rubber pads. A total of 21 rubber pads have been installed between the chamber and supporting pedestals. A sand bag of 800kg was dropped on the chamber floor to measure the natural frequency of the isolation system. Absolute transmissibility has been measured while generating 145㏈ in the chamber. The natural frequency of the chamber is 10.5㎐, which is 80% of estimated value. Overall transmissibility at working frequency range (25㎐-10,000㎐) is less than -6㏈.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.477-482
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• 2002

This research is concerned with the study of an active vibration absorber using piezoelectric actuators and Isolation pad. The active isolation system consists of 4-pairs of PZT actuators bonded on the surface of an aluminum plate and a passive damping material. The active system is connected to the passive system in series. The Signals of the accelerometers are fed into the PZT actuator through the controller. We proposed a new control technique which can deal with the shock as well as the base excitation in this study. The Positive Acceleration Feedback(PAE) tuned to the natural frequency of the vibration isolation system is used to suppress the vibrations caused by the shock using the top accelerometer signal. The Negative Acceleration Feedback (NAF) based on the base acceleration signal is used to counteract the base motion. Experimental results show that the proposed active vibration isolation system can suppress vibrations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.124-129
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• 2018

A non-linear vibration isolation system which is composed of a non-linear spring and a linear damper was proposed in past research. When the support of the isolation system is excited harmonically, the response component of the isolation system mass at the excitation frequency has been calculated approximately using the harmonic balance method. The response was approximated by a single mode, and the result was compared with a numerical result which is assumed as an accurate one. Next, the response was approximated by two modes, and the result was compared with the former one.

• 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 Monitoring and Maintenance
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• v.5 no.3
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• pp.325-343
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• 2018

This study aims to propose a performance-based design method of a novel passive base isolation system, BIO isolation system, which is inspired by an energy dissipation mechanism called 'sacrificial bonds and hidden length'. Fragility functions utilized in this study are derived, indicating the probability that a component, element, or system will be damaged as a function of a single predictive demand parameter. Based on PEER framework methodology for Performance-Based Earthquake Engineering (PBEE), a systematic design procedure using performance and fragility objectives is presented. Base displacement, superstructure absolute acceleration and story drift ratio are selected as engineering demand parameters. The new design method is then performed on a general two degree-of-freedom (2DOF) structure model and the optimal design under different seismic intensities is obtained through numerical analysis. Seismic performances of the biologically inspired (BIO) isolation system are compared with that of the linear isolation system. To further demonstrate the feasibility and effectiveness of this method, the BIO isolation system of a 4-storey reinforced concrete building is designed and investigated. The newly designed BIO isolators effectively decrease the superstructure responses and base displacement under selected earthquake excitations, showing good seismic performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.497-504
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• 2005

This paper presents the results of experimental studies on the equipment isolation effect considering the floor response. For this purpose, shaking table tests were performed. For the measuring the floor response, numerical analysis was performed. For the isolation for the equipment, Natural Rubber Bearing(NRB), High Damping Rubber Bearing(HDRB) and Friction Pendulum System(FPS) were used. Finally, it is presented that the isolation systems used in this test can be adopted for the small equipment isolation. But the rubber bearing used in this study affected to the temperature change very sensitively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.307-312
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• 2006

In this study a vibration isolation system with the cradle-type support was designed so as to reduce the transient vibration due to positioning motion of the moving mass on worktable as well as to achieve the desired isolation efficiency on the floor vibration. The design procedure was performed in the two steps. The first step to select appropriate isolators to meet the isolation efficiency, and the second step is to reduce the transient vibration of the worktable by adopting the cradle-type support. After the application of the selected isolators with the cradle-type support to the system it was shown that the required vibration criterion(VC-D) was easily satisfied and that the undesirable transient vibration was reduced remarkably.