• Structural Monitoring and Maintenance
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• v.3 no.4
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• pp.335-347
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• 2016

One of major errors in flow rate measurement for two-phase flow using an Electrical Capacitance Sensor (ECS) concerns sensor sensitivity under temperature raise. The thermal effect on electrical capacitance sensor (ECS) system for air-water two-phase flow monitoring include sensor sensitivity, capacitance measurements, capacitance change and node potential distribution is reported in this paper. The rules of 12-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance and sensitivity map the basis of Air-water two-phase flow permittivity distribution and temperature raise are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. The cross-sectional void fraction as a function of temperature is determined from the scripting capabilities in ANSYS simulation. The results show that the temperature raise had a detrimental effect on the electrodes sensitivity and sensitive domain of electrodes. The FE results are in excellent agreement with an experimental result available in the literature, thus validating the accuracy and reliability of the proposed flow rate measurement system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.479-480
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.671-672
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• 2008

• Structural Monitoring and Maintenance
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• v.3 no.3
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• pp.297-314
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• 2016

As the study of internal corrosion of pipeline need a large number of experiments as well as long time, so there is a need for new computational technique to expand the spectrum of the results and to save time. The present work represents a new non-destructive evaluation (NDE) technique for detecting the internal corrosion inside pipeline by evaluating the dielectric properties of steel pipe at room temperature by using electrical capacitance sensor (ECS), then predict the effect of pipeline environment temperature (${\theta}$) on the corrosion rates by designing an efficient artificial neural network (ANN) architecture. ECS consists of number of electrodes mounted on the outer surface of pipeline, the sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of two dimensional capacitance sensors are illustrated. The variation in the dielectric signatures was employed to design electrical capacitance sensor (ECS) with high sensitivity to detect such defects. The rules of 24-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. A feed-forward neural network (FFNN) structure are applied, trained and tested to predict the finite element (FE) results of corrosion rates under room temperature, and then used the trained FFNN to predict corrosion rates at different temperature using MATLAB neural network toolbox. The FE results are in excellent agreement with an FFNN results, thus validating the accuracy and reliability of the proposed technique and leads to better understanding of the corrosion mechanism under different pipeline environmental temperature.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.1
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• pp.95-100
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• 1998

The conductance change evoked by step depolarization was studied in primarily cultured rat adrenal chromaffin cells using patch-clamp and capacitance measurement techniques. When we applied a depolarizing pulse to a chromaffin cell, the inward calcium current was followed by an outward current and depolarization-induced exocytosis was accompanied by an increase in conductance trace. The slow inward tail current which has the same time course as the conductance change was observed in current recording. The activation of slow tail current was calcium-dependent. Reversal potentials agreed with Nernst equation assuming relative permeability of $Cs^+\;to\;K^+$ is 0.095. The outward current and tail current were blocked by apamin (200 nM) and d-tubocurarine (2 mM). The conductance change was blocked by apamin and did not affect membrane capacitance recording. We confirmed that conductance change after depolarization comes from the activation of the SK channel and can be blocked by application of the SK channel blockers. Consequently, it is necessary to consider blocking of the SK channel during membrane capacitance recording.

• Transactions on Electrical and Electronic Materials
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• v.14 no.4
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• pp.182-186
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• 2013

We studied the possibility that an air capacitor can be used as a humidity sensor by measuring capacitance change. In order to investigate the possibility, the change of capacitance of an air capacitor due to moisture in air was first considered theoretically, and was then experimentally verified. The capacitance was measured by an LCR impedance meter with a 100-kHz and 1-V ac. The results revealed that the changes in the experimentally measured capacitances were greater than those in the theoretically calculated values. Based on this fact, we knew that an air capacitor could be used as part of a humidity sensing device. We expect the humidity sensor with an air capacitor has characteristics of fast response time, high reliability, and high durability compared with other conventional methods.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.183-190
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• 2003

In this paper, investigated are the machining characteristics such as material removal rate and machining time with respect to discharge area and capacitance in micro electrical discharge machining (MEDM). As discharge area determined by the electrode size and capacitance change, the optimal feedrate to allow the minimum machining time changes. The smaller discharge area is, the lower MRR becomes because of the area effect. As the capacitance increases, MRR also increases. However there is the limit capacitance beyond which the MRR does not increase anymore. As the discharge area increases, the limit capacitance also increases.

• The Journal of Korean Medicine
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• v.36 no.3
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• pp.35-52
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• 2015

Objectives: The objective of this study was to investigate the effects of smoking on the skin bio-electrical capacitance at twelve source points. Methods: Twenty healthy male subjects were assigned to smoking and sham-smoking by a random cross-over design. Skin bio-electrical capacitance was measured at twelve source points for 10 minutes before and after smoking. The change of skin bio-electrical capacitance was analysed. Results: 1. The skin bio-electrical capacitance at LU9, PC7 and LR3 was significantly increased after smoking. 2. In the smoking group, the skin bio-electrical capacitance at the source points of Hand Yin meridians significantly increased compared to that of Foot Yin and Hand Yang meridians. Conclusions: Smoking significantly increased the skin bio-electrical capacitance at the source points of Lung, Pericardium and Liver meridians. Hand Yin meridians appear to be more vulnerable to smoking than other meridians.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.376-380
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• 2009

Surface acoustic wave (SAW) device is widely used as a bandpass filter, a chemical or physical sensor, and an actuator. In this paper, we propose the capacitive gap measurement system with high precision through the signal processing using SAW device. The research process is mainly composed of theoretical part and experimental part. In theoretical part, equivalent circuit model was used to simulate the SAW response by the change of capacitance. In experimental part, commercialized capacitor was used to see the SAW response by the change of load capacitance. After that, gap adjustment system was made physically and the SAW response by the change of gap which caused the capacitance change was measured. And resolution and stroke was decided comparing the signal change and basic measurement noise level.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.129-135
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• 2023

An analytical threshold voltage model is presented to observe the change in threshold voltage shift ΔV_th of a junctionless double gate MOSFET using ferroelectric-metal-SiO₂ as a gate oxide film. The negative capacitance transistors using ferroelectric have the characteristics of increasing on-current and lowering off-current. The change in the threshold voltage of the transistor affects the power dissipation. Therefore, the change in the threshold voltage as a function of theferroelectric thickness is analyzed. The presented threshold voltage model is in a good agreement with the results of TCAD. As a results of our analysis using this analytical threshold voltage model, the change in the threshold voltage with respect to the change in the ferroelectric thickness showed that the threshold voltage increased with the increase of the absolute value of charges in the employed ferroelectric. This suggests that it is possible to obtain an optimum ferroelectric thickness at which the threshold voltage shift becomes 0 V by the voltage across the ferroelectric even when the channel length is reduced. It was also found that the ferroelectric thickness increased as the silicon thickness increased when the channel length was less than 30 nm, but the ferroelectric thickness decreased as the silicon thickness increased when the channel length was 30 nm or more in order to satisfy ΔV_th=0.