• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.165-170
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• 2011

A large number of seismic isolation systems have been developed since the early 1970s. They are basically a combination of elastomeric bearing and energy dissipators. The investigation described in this paper analyzes shear property and the frequency dependence of Lead Rubber Damper(LRD). Lead Rubber Damper is similar in shape and performance property to Lead Rubber Bearing. Experimental condition ranges from 20 to 200% in share strain and from 0.1 to 1.0Hz in frequency. When the shear strain is increased, effective stiffness and damping ratio are decreased. When the frequency is increased, change of the behavior characteristic is subtle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.349.1-349
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• 2002

This paper presents investigation of damping characteristics of squeeze mode type MR mount experimently. The MR mount proposed in the study has variable damping characteristics according to the applied magnetic field strength. Impact and force excitation tests were performed. The dynamic property of the mount using MR fluid was compared with that of the mount using conventional oil. (omitted)

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.11
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• pp.922-927
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• 2002

A variable structure control (VSC) based model following control system that possesses fault detection and isolation (FDI) capability as well as fault tolerance property is proposed. The nonlinear part of the proposed control law. whose magnitude is determined by sliding variables, plays the role of suppressing fault effect. Thus, approximate fault reconstruction is also possible via the analysis of sliding variables. The proposed algorithm is applied to an active suspension system of pound vehicles to verify its applicability.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.221-238
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• 2023

This paper developed and examined a novel passive vibration isolator (i.e., "X-inerter") motivated by combining a bio-inspired structure and a rack-pinion inerter. The bio-inspired structure provided nonlinear stiffness and damping owing to its geometric nonlinearity. In addition, the behavior was further enhanced by a gear inerter that produced a special nonlinear inertia effect; thus, an X-inerter was developed. As a result, the X-inerter can achieve both high-static-low-dynamic stiffness (HSLDS) and quasi-zero stiffness (QZS), obtaining ultra-low frequency isolation. Furthermore, the installed inerter can produce a coupled nonlinear inertia and damping effect, leading to an anti-resonance frequency near the resonance, wide isolation region, and low resonance peak. Both static and dynamic analyses of the proposed isolator were conducted and the structural parameters' influence was comprehensively investigated. The X-inerter was proven to be comparatively more stable in the ultra-low frequency than the benchmarking QZS isolator due to the nonlinear damping and inertia properties. Moreover, the inertia effect could suppress the bio-inspired structure's super- and sub-harmonic resonance. Therefore, the X-inerter isolator generally possesses desirable nonlinear stiffness, nonlinear damping, and unique nonlinear inertia, designed to achieve the ultra-low natural frequency, the anti-resonance property, and a wide isolation region with a low resonance peak.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.601-611
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• 2016

The research, development and use of seismic isolation systems have been increasing with the gradual development of structure safety assurance methods for earthquakes. The High Damping Rubber Bearing (HDRB), one type of seismic isolation system, is a Laminated Rubber Bearing using special High Damping Rubber. However, as its damping function is slightly lower than that of the Lead Rubber Bearing, a similar seismic isolation system, its utilization has not been high. However, the HDRB has a superior damping force to the Natural Rubber Bearing, which has similar materials and shapes, and the existing Lead Rubber Bearing has a maleficence problem in that it contains lead. Thus, studies on HDRBs that do not use lead have increased. In this study, a test targeting the HDRB was done to examine its various dependence properties, such as its compressive stress, frequency and repeated loading. To evaluate the HDRB's seismic performance in response to several earthquake waves, the shaking table test was performed and the results analyzed. The test used the downscaled bridge model and the HDRB was divided into seismic and non-seismic isolation. Consequently, when the HDRB was applied, the damping effect was higher in the non-seismic case. However, its responses on weak foundations, such as in Mexico City, represented increased shapes. Thus, its seismic isolator.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.64-71
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• 2008

SAW (Surface Acoustic Waves) ID (identification) tags have been designed and implemented for RFID (Radio frequency IDentification) systems. With SAW ID tag of pulse position encoding method, the data capacity increased 3 times compared with SAW ID tag of amplitude on/off method. Two different kinds of SAW ID tag receiver systems, heterodyne and homodyne receiver systems, were made. The direct conversion receiver showed better isolation property, 10 dB improvement than the heterodyne receiver to increase wireless interrogation distance.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.612-618
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• 2012

In this paper, in order to prevent electric shock of high voltage system of HFCV after crash test, insulation performance measurement methods were studied. Under conditions of in-use, insulation performance tests can be divided into measurement method using the vehicle's own RESS as DC voltage source and measurement method using DC voltage from off-vehicle sources. However, these tests can not be applied after a post-crash because parts of high voltage system cover should be removed, and insulation performance can be influenced during these tests. Therefore, we proposed post-crash insulation performance test methods for preventing electric shock through problem analysis of previous post-crash insulation performance tests. Also, test equipment which can measure voltage absence and total energy was developed. We verified performance of the equipment through experiments with vehicle test.

• The Korean journal of helicobacter and upper gastrointestinal research
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• v.18 no.3
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• pp.157-161
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• 2018

Liquid biopsy, the analysis of circulating biomarkers from peripheral blood, such as circulating tumor cells (CTCs) and circulating tumor DNA, and exosomes, offers a less invasive, new source of cancer-derived materials that may reflect the status of the disease better and thereby contribute to personalized treatment. Recent advances in microfluidics and molecular analysis technologies have resulted in greatly improved CTC enumeration and detection. In this article, we review commercially available technologies used to isolate CTCs from peripheral blood, including immunoaffinity and label-free, physical property-based isolation methods. Although enormous technological progress has been made, especially within the last decade, only a few CTC detection methods have been approved for routine clinical use. Here, we provide an overview of the current CTC isolation methods and examples of their potential application for early diagnosis, prognosis, treatment monitoring, and prediction of resistance to cancer therapy. Furthermore, the challenges that remain to be addressed before such tools are implemented for routine use in clinical settings are discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.34-40
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• 2019

We performed shape optimization of an anti-vibration rubber assembly which is used in the field option cabin of agricultural tractors to improve the vibration isolation capability. To characterize the hyper-elastic material property of rubber, we performed uniaxial and biaxial tension tests and used the data to calibrate the material model applied in the finite element analyses. We conducted a field test to characterize the input excitation from the tractor and the output response at the cabin frame. To account for the nonlinear behavior of rubber, we performed static analyses to derive the load-displacement curve of the anti-vibration rubber assembly. The stiffness of the rubber assembly could be calculated from this curve and was input to the harmonic analyses of the cabin. We compared the results with the test data for verification. We utilized Taguchi's parameter design method to determine the optimal shape of the anti-vibration rubber assembly and found two distinct shapes with reduced stiffness. Results show that the vibration at the cabin frame was reduced by approximately 35% or 47.6% compared with the initial design using the two optimized models.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.303-309
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• 2011

Laminated rubber bearing is the most commonly used device for seismic base isolation of bridge structures. It is important to know performance and behavior characteristics of the laminated rubber bearings. The main evaluation factors of the rubber bearing are classified as compressive, shear and tensile behavior characteristics. The reference data of compressive and shear characteristics are rich, but the reference data of tensile characteristics is scarce. In this study, tensile test results of the rubber bearing with variation of shape factor and shear deformation are investigated for mechanical property. When tensile deformation in normal condition is increasing, tensile cycle behavior curve becomes non-linear and tensile breaking point is 300%. On the other hand, tensile breaking point is shear deformation condition is about 40%. Furthermore, when shape factor is lower, tensile breaking point is decrease. This results mean that tensile breaking point is decreased in triaxial tensile deformation because of cracks caused by internal void of the rubber bearings. This experimental data can be used as the reference data of tensile characteristics for designing seismic isolation of structures.