• Smart Structures and Systems
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• v.4 no.1
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• pp.35-46
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• 2008

In this paper the authors address the problem of comparing two different smart damping techniques using the numerical modelling of the electro-mechanical impedance for plate structures partially treated with active constrained layer damping treatments. The paper summarizes the modelling procedures including a finite element formulation capable of accounting for the observed behaviour. The example used is a smart cantilever plate structure containing a viscoelastic material (VEM) layer sandwiched between a piezoelectric constrained layer and the host vibrating plate. Comparisons are made between active constrained layer and active damping only and based on the resonance frequency amplitudes of the electrical admittance numerically evaluated at the surface of the piezoelectric model of the vibrating structure.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.221-226
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• 2006

Electrical impedance tomography (EIT) is a technique for determining the electrical conductivity and permittivity distribution within the interior of a body from measurements made on its surface. One recent application area of the EIT is the detection of breast cancer by imaging the conductivity and permittivity distribution inside the breast. The present "gold standard" for breast cancer detection is X-ray mammography, and it is desirable that EIT and X-ray mammography use the same geometry. This paper presents a forward model of a simplified mammography geometry for EIT imaging. The mammography geometry is modeled as a rectangular box with electrode arrays on the top and bottom planes. A forward model for the electrical impedance imaging problem is derived for a homogeneous conductivity distribution and Validated by experiment using a phantom tank.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.576-579
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• 2008

Electrical impedance(EIT) for the multi-phase flow visualization is an imaging modality in which the resistivity distribution of the unknown object is estimated based on the known sets of injected currents and measured voltages on the surface of the object. In this paper, an EIT reconstruction algorithm based on the extended Kalman filter(EKF) is proposed. The EIT reconstruction problem is formulated as a dynamic model which is composed of the state equation and the observation equation, and the unknown resistivity distribution is estimated recursively with the aid of the EKF. To verify the reconstruction performance of the proposed algorithm, experiments with simulated multi-phase flow are performed.

• ETRI Journal
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• v.30 no.4
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• pp.597-599
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• 2008

This letter presents the design of a small and low-profile RFID tag antenna in the UHF band that can be mounted on metallic objects. The designed tag antenna, which uses a ceramic material as a substrate, consists of a radiating patch and a microstrip line with two shorting pins for a proximity-coupled feeding structure. Using this structure, impedance matching can be simply obtained between the antenna and tag chip without a matching network. The fractional impedance bandwidth for $S_{11}$ <3 dB and radiation efficiency are about 1.4% and 56% at 911 MHz, respectively. The read range is approximately from 5 m to 6 m when the tag antenna is mounted on a metallic surface.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.183-186
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• 1993

We have developed a bioimpedance measurement system for impedance cardiography and pneumography. The system injects 50kHz, $200mA_{p-p}$ curreng into the thorax and measures the voltage changes using body surface electrodes. We used the four-electrode method for tile measurement of cardiac singnals and two-electrode method for respiratory signals. We developed a Microsoft Windows program for the acquisition, display, storage, and processing of impedance signals.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.26-26
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• 2006

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.660-661
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• 2013

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.512-513
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• 2000

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.157-162
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• 2011

The stability at elevated temperatures of a surface film formed on a graphite electrode in lithium secondary batteries was investigated by transmission electron microscopy (TEM) and electrochemical AC impedance spectroscopy (EIS). TEM analysis revealed that the surface film partly dissolved in the electrolyte solution during storage at $60^{\circ}C$, resulting in a decrease in the thickness of the surface film and a change in its morphology to a porous structure. On the other hand, an increase in the impedance of the surface film which is attributable to a change in composition of the surface film was confirmed by EIS analysis during the storage at $60^{\circ}C$. It was also shown that the addition of vinylene carbonate or 1,3-propane sultone or etylene sulfite, even if limited, improves the stability of the surface film at elevated temperatures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.9
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• pp.744-750
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• 2013

In this paper, we proposed new type of an artificial magnetic conductor(AMC) structure, which has a high impedance surface for realizing the meta-material characteristics. The designed AMC structure set a goal of 3.2GHz, and the reflector, which consists of periodically arrayed AMCs is fabricated and measured. The high impedance improves the reflection coefficient, decreases the system size and interference, and increases the antenna performance. The structure has embodied the high impedance by the thickness and relative permitivity of the dielectric substrate and the design configuration without the metallic via hole which connects the AMC to the GND. The bandwidth is 150% broader than the similar AMC structures. Also, the distance between the antenna and the AMC reflector is decreased by ${\lambda}/10$ as working as the metal(PEC) reflectors. The antenna radiation characteristics are 3dB increased at 10mm away from reflector by measurement. The proposed reflector could be inserted in the portable mobile devices, and the antenna's performance has improved by the reflector. The specific absorption rate is dramatically decreased over 94% because the back radiation of the antenna is shielded.