• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.53-59
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• 2005

In this study, the isolation system for multi-mechanism HIF (high impulsive force) device has been investigated. For this purpose, parameter optimization process has been performed based on the simplified isolation system model under constraints of moving displacement and transmitted force. The design parameters for multi-mechanism HIF device have been derived with respect to HIF system I and HIF system II, respectively. In order to implement the dynamic absorbing system, the dual stage hydro-pneumatic damper and magnetorheological damper with semi-active control scheme are considered. Finally, the performance of the designed prototype isolation system has been evaluated by experimental works under actual operating conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.900-903
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• 2014

Fly-wheel, Gimbal antenna, CMG, Spaceborne cyrocooler generate micro-vibration during their on-orbit operation as well as implementing their own function. To comply with the mission requirement of high resolution observation satellite, additional technical efforts have been required to isolate the micro-vibration derived from such payloads by applying the vibration isolator. In this study, we proposed a passive isolator using SMA mesh washer, which guarantees the structural safety of both micro-vibration disturbance source and itself under harsh launch vibration loads without an additional holding mechanism and the micro-vibration isolation performance on orbit environment. To verify the micro-vibration isolation performance of the proposed vibration isolator, we performed the micro-vibration isolation measurement test using the dedicated micro-vibration measurement device proposed in this study.

• Journal of Information Technology Applications and Management
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• v.13 no.4
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• pp.141-153
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• 2006

According to supply of super high way internet service, importance of security becomes more emphasizing. Therefore, flawless security solution is needed for blocking information outflow when we send or receive data. large enterprise and public organizations can react to this problem, however, small organization with limited work force and capital can't. Therefore they need to elevate their level of information security by improving their information security system without additional money. No hackings can be done without passing invasion blocking system which installed at the very front of network. Therefore, if we manage.isolation log effective, we can recognize hacking trial at the step of pre-detection. In this paper, it supports information security manager to execute isolation log analysis very effectively. It also provides isolation log analysis module which notifies hacking attack by analyzing isolation log.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.954-954
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• 2005

In this study new vibration isolation system was designed so as to decouple translational motion and rotational motion of a workstation as well as to maximize an efficiency of vibration isolation. Whole motion of the workstation as well as the transmitted vibration from the floor were compared at the two conditions; with and without the cradle system. It was shown that the cradle system had a clear effect to suppress the roiling motion of the workstation.

• Earthquakes and Structures
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• v.3 no.3_4
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• pp.249-270
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• 2012

This paper investigates the effectiveness of widely used identification methods to identify the response of seismically isolated structures supported on bearings with bilinear behavior. The paper shows that while both time domain and frequency domain methods predict with high accuracy the modal characteristics of structures isolated by linear isolation system, their performance degrades appreciably when the isolation system exhibits bilinear behavior even when its strength assumes moderate values (say 5% of the weight). The paper also shows that the natural period of isolated structure that results from bilinear isolation systems can be satisfactorily predicted with wavelet analysis.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.142-145
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• 2002

This paper presents the electromagnetic field water treater system with the high performance for a good quality of water. The electromagnetic field water treater consists of a solion, a solion body. and a high voltage converter. The high voltage converter is controlled by PWM current controller. The high voltage converter of 13W is designed for an isolation operation ramp. an isolation current detector, and an over current protector. Using the high voltage PWM converter, the system with the proposed electromagnetic field water treater can be controlled easily. Simulation and experimental results show the effectiveness of the system strategy proposed for the scale rejection.

• Smart Structures and Systems
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• v.25 no.2
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• pp.155-167
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• 2020

This paper demonstrates a real-time hybrid substructuring (RTHS) shake table test to evaluate the seismic performance of a base isolated building. Since RTHS involves a feedback loop in the test implementation, the frequency dependent magnitude and inherent time delay of the actuator dynamics can introduce inaccuracy and instability. The paper presents a robust stability and performance analysis method for the RTHS test. The robust stability method involves casting the actuator dynamics as a multiplicative uncertainty and applying the small gain theorem to derive the sufficient conditions for robust stability and performance. The attractive feature of this robust stability and performance analysis method is that it accommodates linearized modeled or measured frequency response functions for both the physical substructure and actuator dynamics. Significant experimental research has been conducted on base isolators and dampers toward developing high fidelity numerical models. Shake table testing, where the building superstructure is tested while the isolation layer is numerically modeled, can allow for a range of isolation strategies to be examined for a single shake table experiment. Further, recent concerns in base isolation for long period, long duration earthquakes necessitate adding damping at the isolation layer, which can allow higher frequency energy to be transmitted into the superstructure and can result in damage to structural and nonstructural components that can be difficult to numerically model and accurately predict. As such, physical testing of the superstructure while numerically modeling the isolation layer may be desired. The RTHS approach has been previously proposed for base isolated buildings, however, to date it has not been conducted on a base isolated structure isolated at the ground level and where the isolation layer itself is numerically simulated. This configuration provides multiple challenges in the RTHS stability associated with higher physical substructure frequencies and a low numerical to physical mass ratio. This paper demonstrates a base isolated RTHS test and the robust stability and performance analysis necessary to ensure the stability and accuracy. The tests consist of a scaled idealized 4-story superstructure building model placed directly onto a shake table and the isolation layer simulated in MATLAB/Simulink using a dSpace real-time controller.

• Geomechanics and Engineering
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• v.27 no.6
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• pp.537-550
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• 2021

There are various technical problems need to be solved in the construction process of pre-setting an isolation wall into a double lane in the outburst prone mine. This study presents a methodology that pre-setting an isolation wall into a double lane without a coal pillar. This requires the excavation of two small section roadways to dig a wide section roadway, followed by construction of the separation wall. During this process the connecting lane is reserved. In order to ensure the stability of the separation wall, the required bearing capacity of the isolation wall is 4.66 MN/m and the deformation of the isolation wall is approximately 25 cm. To reduce the difficulty of implementing support the roadway is driven by 5 m/d. After the construction of the separation wall, the left side coal wall is brushed 1.5 m to make the width of the gas roadway reach 2.5 m and the roadway support utilizes anchor rod, ladder beam, anchor cable beam and net configuration. During construction, the concrete pump and removable self-propelled hydraulic wall mold are used to pump and pour the concrete of the isolation wall. In the process of mining, the stress distribution of coal body and isolation wall is detected and measured on site. The results demonstrate that the deformation of the surrounding rock of roadway and separation of roof in the roadway is small. The stress of the bolt and anchor cable is within equipment tolerance validating their selection. The roadway is well supported and the intended goal is achieved. The methodology can be used for reference for similar mine gas control.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.949-952
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• 2005

According to the national space program in Korea, is satellites will be launch into space up to 2015. Especially, KARI is going to develope of its own a high resolution camera of less than 1m to be mounted on next Multipurpose Satellite. When performing testing of large spacecraft or hardware that will be launched into orbit, it is necessary to conduct a testing with space-simulated environment. To achieve this requirement, thermal vacuum chamber is generally used. KARI has been developed a very Large Thermal Vacuum Chamber(LTVC) from 2003 to accomodate future space program, such as KOMPSAT, COMS, and Launch vehicles. This new facility will be used to qualify the first self developed High Resolution Camera, which will be loaded on KOMPSAT-3. To perform an optical test for space camera, it is necessary to provide vibration free environment. Thus the vibration responses on the optical table due to external vibration should be minimized by using a special isolation system. In this paper, we propose the concept design of vibration isolation system for the development of the high resolution camera.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.183-188
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• 2016

This paper presents the design and characterization of wide band ohmic microswitch with an actuation voltage as low as 20~25 V, and a restoring force of 14.1 μN. The design of the proposed switch is primarily composed of an electrostatic actuator, bridge membrane, cantilever (beam) and coplanar waveguide, suspended over the substrate. The analysis shows an insertion loss of −0.002 dB at 1GHz and remains as low as −0.35 dB, even at 100 GHz. The isolation loss of the switch is sustained at −21.09 dB at 100GHz, with a peak value of −99.58 dB at 1 GHz and up-state capacitance of 4 fF. To our knowledge, this is the first demonstration of a series contact switch, which works over a wide bandwidth (DC-100 GHz) and with such a high and sustained isolation, even at high frequencies and with an excellent figure of merit (f_c=1/2.pi.Ron.Cu= 39.7 THz).