• 한국응용과학기술학회지
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• 제24권4호
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• pp.377-382
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• 2007

We designed capacitance sensor in order to examine characteristics of W/O type emulsified fuel, so it concluded the following conclusions. The capacitance value of emulsified fuel, using with capacitance sensor, increases as water content increases due to the coalescence. When surfactant increases, the capacitance value decreases, the condition of W/O type emulsified fuel was maintained stably. There was revealed the capacitance value difference of W/O type emulsified fuel in in according to water content. We checked the phase separation of emulsified fuel with the capacitance value difference. The surfactant(HLB=5.4) had better stable condition than surfactant(HLB=4.3). Also, we confirmed that two mixture surfactants were better than one surfactant.

• Structural Monitoring and Maintenance
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• 제3권4호
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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.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1720-1725
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• 2015

The performance of the AlGaN/GaN MSM-2DEG varactor with different dielectric films deposited by the E-beam deposition is investigated in detail. The capacitance swing and the capacitance ratio of the varactor without dielectric film as well as with, SiO₂, Gd₂O₃, and Si₃N₄ films, respectively, are determined by electrodes of varying areas. The maximum capacitance, the minimum capacitance and the capacitance ratios are proportional to the increasing of the electrode areas. The capacitance ratio determined by the maximum and the minimum capacitance is found to be 18.35 (with Si₃N₄ dielectric film) and 149.51 (without dielectric film), respectively. The transition voltages of the fabricated varactors are almost the same for a bias voltage of about ±5 V and leakage current can be lower three orders of magnitude while the varactors with dielectric films. The tunability of the capacitance ratio makes the AlGaN/GaN MSM-2DEG varactor with a dielectric film highly useful in multirange applications of a surge free preamplier.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1225-1228
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• 2003

본 논문에서는 Coupling capacitance 변화량이 Static coupling capacitance 값보다 클 수 있다는 것을 새로운 테스트 회로를 이용하여 실험적으로 증명하였다. 테스트 회로는 배선의 지연시간이 배선의 저항보다는 배선의 정전용량에만 의존하도록 하여 배선의 지연시간을 평가함으로써 배선의 정전용량의 변화 즉, Coupling capacitance 의 변화량을 정확히 평가할 수 있도록 하였다. 0.15 ㎛ CMOS 기술을 이용하여 실험한 결과 In-phase crosstalk 인 경우에는 변화량이 Static coupling capacitance 보다 작았지만 Anti-phase 인 경우에는 Static coupling capacitance 보다 크게 나타남을 보여주고 있다. 따라서 배선에 의한 정확한 지연시간 평가를 위해서는 Crosstalk 이 발생한 경우의 Coupling capacitance 변화량을 정확히 반영하는 것이 매우 필요함을 알 수 있다.

• 센서학회지
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• 제13권2호
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• pp.133-138
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• 2004

Today, the obstacle detection system has massive size and restrictive detection range. To solve these problems, this paper proposes the capacitance variation detector using the variated capacitance value as a result of the obstacle approaching. If obstacle approaches, the capacitance value of capacitance sensor is increased and the operating frequency of oscillator is decreased. Then this changed frequency appears to the output of the mixer that operate down conversion. The capacitance variation detector is produced by Hynix$0.35{\mu}$ CMOS process. In experiment result, the frequency of final output is 6.81 MHz at no obstacle and 31.45 MHz at approaching obstacle. In conclusion, proposed capacitance variation detector has small size, low power consumption and easiness to set up anywhere. So it is expected to substitute the obstacle detector.

• 대한전자공학회논문지SD
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• 제42권9호
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• pp.61-72
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• 2005

본 논문에서는 평면계획 단계에서 모듈의 전원 잡음을 줄이기 위해 필요한 decoupling capacitance를 효과적으로 할당하는 방법을 제시한다. 먼저, 각 모듈의 decoupling capacitance가 과대평가되고 추가 면적 삽입으로 모듈의 전원 잡음이 변하는 기존 접근 방법의 문제점을 살펴보고, 이를 해결할 수 있는 새로운 방법을 제시한다. 또한, 선형프로그래밍 방법보다 빠른 시간 내에 decoupling capacitance 면적을 위한 빈 공간을 할당하는 간단한 휴리스틱 방법을 제안한다. 실험결과에서 제시된 방법은 Zhao[4]의 방법과 비교하여 decoupling capacitance 면적이 평균 $7.9\%$ 감소하고, 이로 인해 평면계획 결과의 전체 면적과 와이어 길이가 감소하였다. 또한, 추가 면적 삽입으로 인한 모듈의 전원 잡음 문제를 잘 해결하고 있음을 확인하였다. 수행시간 비교에서는 평균 $11.6\%$의 향상을 보였다.

• 대한한의학회지
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• 제36권3호
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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.

• Journal of Power Electronics
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• 제18권6호
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• pp.1912-1919
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• 2018

The output capacitance of power semiconductor devices is important in determining the switching losses and in the operation of some resonant converter topologies. Thus, it is important to be able to accurately determine the output capacitance of a particular device operating at elevated power levels so that the contribution of the output capacitance discharge to switch-on losses can be determined under these conditions. Power semiconductor switch manufacturers usually measure device output capacitance using small-signal methods that may be insufficient for power switching applications. This paper shows how first principle methods are applied in a novel way to obtain more relevant large signal output capacitances of Gallium-Nitride (GaN) FETs using the drain-source voltage transient during device switch-off numerically. A non-linear capacitance for an increase in voltage is determined with good correlation. Simulations are verified using experimental results from two different devices. It is shown that the large signal output capacitance as a function of the drain-source voltage is higher than the small signal values published in the data sheets for each of the devices. It can also be seen that the loss contribution of the output capacitance discharging in the channel during switch-on correlates well with other methods proposed in the literature, which confirms that the proposed method has merit.

• 한국염색가공학회지
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• 제31권2호
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• pp.65-76
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• 2019

A multi-point touch input sensor having different sizes or different capacitance touch points connected by only one pair of signal transmission lines was fabricated using a polyimide film coated with a thin copper plate. The capacitance increases with the decrease in the number of sheets of fabric spacers placed between the two sheets of the polyimide film. Therefore, the touch input sensor could be manufactured without fabric spacers, which was possible by the action of the polyimide film as a dielectric material in the capacitor. On the multi-point touch sensor, higher capacitance was obtained when pressing wider-area touch points with 10mm to 25mm diameter on average. However, the capacitance of a system comprising two sheets of touch sensors was considerably low, causing a serious overlap of the capacitance values according to the data collected from the reliability test. Although the capacitance values could be increased by stacking several sheets of touch sensors, the overlap of data was still observed. After reducing the size of all touch points to 10mm and stacking up to eight sheets of sensors, reliable and consistent capacitance data was obtained. Five different capacitance signals could be induced in the sensors by pushing touch points simultaneously.

• 한국정밀공학회지
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• 제20권12호
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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.