• Proceedings of the KSME Conference
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• 2001.06c
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• pp.275-280
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• 2001

Seismic isolator system is one of the most widely used base isolation system in order to control the vibration of structure against earthquake excitation. The evaluation of vulcanization time in molding the rubber bearing is very important for both proper ability of isolator and efficiency of manufacture. This paper deals with experimental measurement of temperature of isolator with senor inside in it, and compared with the result of FEA in order to evaluate the vulcanization time. Properties of rubber bearing which is used in the FEA are obtained by controlling the specific heat of rubber. With the obtained properties of rubber, the isolator is analysed by FEA. As a result, an appropriate analytical vulcanization time is obtained. This time is regarded as an appropriate temperature, which is used to effective manufacture.

• Journal of Drive and Control
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• v.13 no.3
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• pp.8-14
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• 2016

This study describes the effect of the critical pressure ratio of a control valve on the performance of an air spring system composed of an air spring, auxiliary chamber, control valve and mass in order to suggest a more efficient design for an air spring system. The critical pressure ratio of the control valve is assumed to have a fixed value, but the critical pressure ratio of the control valve is known to have various values between 0.05 and 0.6, and the effect of the variation of the critical pressure ratio on the performance of the air spring system has not yet been reported. The analysis derives nonlinear and linear governing equations of the air spring system, including the critical pressure ratio of the control valve. This simulation study is presented to show that the impedance and transmissibility characteristics of the air spring system change due to variations in the critical pressure ratio of the control valve as well as its sonic conductance. As a result, the critical pressure ratio of the control valve should be maintained as large as possible to improve the vibration isolation characteristics of the air spring system.

• Earthquakes and Structures
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• v.8 no.4
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• pp.889-913
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• 2015

Structural vibration characteristics of a semi-active base-isolated building were investigated using seismic observation records including those of the 2011 Great East Japan earthquake (Tohoku earthquake). Three different types of analyses were conducted. First, we investigated the long-term changes in the natural frequencies and damping factors by using an ARX model and confirmed that the natural frequency of the superstructure decreased slightly after the main shock of the Tohoku earthquake. Second, we investigated short-term changes in the natural frequencies and damping factors during the main shock by using the N4SID method and observed different transition characteristics between the first and second modes. In the second mode, in which the superstructure response is most significant, the natural frequency changed depending on the response amplitude. In addition, at the beginning of the ground motion, the identified first natural frequency was high possibly as a result of sliding friction. Third, we compared the natural frequencies and damping factors between the conditions of a properly functional semi-active control system and a nonfunctional system, by using the records of the aftershocks of the Tohoku earthquake. However, we could not detect major differences because the response was probably influenced by sliding friction, which had a more significant effect on damping characteristics than did the semi-active dampers.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.121-130
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• 2021

Foot bionic robot could be supported and towed through a series of discrete footholds and be adapted to rugged terrain through attitude adjustment. The vibration isolation of the robot could decouple the fuselage from foot-end trajectories, thus, the robot walked smoothly even if in a significant terrain. The gait programming and foot end trajectory algorithm were simulated. The quadruped robot of parallel five linkages with eight degrees of freedom were tested. The kinematics model of the robot was established by setting the corresponding coordinate system. The forward and inverse kinematics of both supporting and swinging legs were analyzed, and the angle function of single leg driving joint was obtained. The trajectory planning of both supporting and swinging phases was carried out, based on the control strategy of compound cycloid foot-end trajectory planning algorithm with zero impact. The single leg was simulated in Matlab with the established kinematic model. Finally, the walking mode of the robot was studied according to bionics principles. The diagonal gait was simulated and verified through the foot-end trajectory and the kinematics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.915-921
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• 2017

Recently, studies to reduce vibration and noise of automobiles have been actively conducted. However, previous studies did not concentrate on the optimization of the mount system with passive or active mounts. This study analytically studies an active mounting system with three active structural paths between source and receiver and the feasibility has been verified. Active mounting system has a coupled structure of piezoelectric stack actuators and passive mounts. A dynamic model of the whole system is prepared and the control force and phase of the stack actuators in each path are determined to target full isolation of each path. Its performance on vibration attenuation is investigated and based on it, optimized combinations of passive and active paths for the best attenuation are presented.

• Journal of Korean Association for Spatial Structures
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• v.16 no.3
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• pp.99-106
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• 2016

The proposed hybrid damper installs at a coupling beam and consists of a high-damping rubber (HDR) and steel pin. The proposed hybrid damper adopted a pin-lock system acts as a viscoelastic damper under wind load (small displacement) while it behaves as a hysteretic damper under earthquake load (large displacement). In this paper, the pin-lock mechanism and structural performance of the proposed hybrid damper is evaluated through experiment. Experiments were carried out with the variables which displacement, loading frequency and steel pin quantities were used. Test results showed that the pin-lock mechanism and the performance of the hybrid damper under a large displacement were verified. Also equivalent damping ratios of HDR were increasing at a small displacement as displacement amplitudes were increasing. However HDR did not depend on frequency.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.221-230
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• 2004

In this paper, the dynamic response of a multi-story steel moment resisting frame equipped with viscoelastic dampers or lead rubber bearing type isolators subjected to seismic loads is investigated analytically. The objective of this study is to find the best location of viscoelastic dampers by the maximum stress method and maximum story drifts method from structure analysis. Also, a secondary objective of the study is to compare the member force, combined stress, and natural period of the structure retrofitted with viscoelastic dampers or lead rubber bearing type isolators to find effective vibration control method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.111-114
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• 2010

MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the steady operational state. To modify the middle flange and rip of inlet valve design by Computer Aided Structural Analysis for improvement of EM core functions. In result, it has been verified to improve performance of EM by tests.