• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.60-67
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• 2007

A signal conditioning circuit for capacitive displacement sensors was developed using a high frequency modulation/demodulation method, and its performance was evaluated. Since capacitive displacement sensors can achieve high resolution and linearity, they have been widely used as precision sensors within the range of several hundred micrometers. However, they inherently have a limitation in low frequency range and some nonlinearity characteristics and so a specially designed signal conditioning circuit is needed to handle these properties. The developed signal processing circuit consists of three parts: linearization, modulation/demodulation, and nonlinearity compensation. Each part was constructed discretely using several IC chips and passive elements. An evaluation system for precision displacement sensors was developed using a laser interferometer, a precision stage, and a PID position controller. The signal processing circuit was tested using the evaluation system in the respect of resolution, repeatability, linearity, and so on. From the experimental results, we know that a highly linear voltage output can be obtained successfully, which is proportional to displacement and the nonlinearity of output is less than 0.02% of full range. However, in the future, further investigation is required to reduce noise level and phase delay due to a low-pass filter. The evaluation system also can be applied effectively to calibration and evaluation of precision sensors and stages.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.21-27
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• 2003

The copolymers with various composition of methyl methacrylate (MMA), ethyl methacrylate (EMA), methacrylic acid (MA) and hydroxyethyl methacrylate (HEMA) were synthesized for capacitive humidity sensitive materials. The capacitive humidity sensor consisted of a polymethacrylate film coated on both sides with gold electrode. Capacitance versus relative humidity increased with HEMA content in the copolymer. In the case of self-crosslinkable MMA/MA/HEHA= 40/10/10, the average capacitance at 30%RH, 60%RH and 90%RH are 102, 134 and 166 pF, respectively. And also, the hysteresis, temperature cycle and long-term stability were evaluated as a capacitance humidity sensor.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1155-1157
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• 2011

본 논문에서는 가전기기의 대기전력 저감을 위해 Capacitive Divider Power Supply(CDPS)로 전원을 공급받는 고효율 전원제어회로를 제안하였다. 이 제어회로는 220 V의 AC 전압을 높은 효율로 기기의 구동용 저전압 DC로 변환하기 위하여 기존의 변압기나 SMPS를 사용하는 대신 커패시터 분압기(Capacitive Divider)를 사용하여 전원을 공급하도록 제작되었으며, 대기 상태에서 교류전력선과 가전기기를 완전히 분리시킨 상태에서 적외선 수신기, MCU, 래치 타입 릴레이 등의 소자를 이용하여 기존 상용 리모컨으로도 전원제어가 가능하도록 설계되었다. 설계된 회로의 소비전력은 2.2 mW이며 본 논문에서 제안한 전원제어회로를 대기전력이 700 mW인 모니터에 적용하여 측정한 결과 대기전력이 7 mW로 낮아지는 것을 확인하였으며, 태양전지를 보조전원으로 추가 할 경우 태양전지에서 공급해주는 전력만큼 대기전력이 감소함을 확인하였다.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.34-39
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• 2014

This paper is aimed to prevent danger of electrical fire at cattle barn to detect resistive and capacitive leakage current component for wiring type and length. In order to analysis for electric leakage component for cattle barn sizes and normal buildings, this paper was studied field state investigation which are at cattle barn companies(10 companies) in Cheong-won location and normal buildings at Nam-bu market in Jeon-ju location. Market to deduce the problems of electric leakage component is analyzed. The resistive and capacitive leakage current component for wiring type and length is analyzed at Beon-young cattle barn. Results show that electric leakage component suggested in this paper are valuable and usable to electrical fire in leakage current based on environment factor, which will prevent severe damage to human beings and properties and reduce the electrical fires in cattle barn. It is acceptable for electrical equipment use in an cattle barn.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1835-1841
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• 2006

Demand of enhanced bilge separation sensor system has been recently increased due to the severe regulation reinforcement of MEPC(Marine Environment Production Committee). Up to date bilge separation sensor has to be extremely accurate and highly reliable. To design and build such a bilge separator. a precise oily water separation level sensor that distinguishes oil from water is critical. Three dimensional simulations have been carried out to figure out the characteristics of capacitive level sensors, which grounds the finding of the parameters required to design the sensors. The parasitic capacitance problem which is inherent to capacitive level sensors has been taken care of. This paper concludes with the future research direction that can be pursued with the newly defined parameters of the capacitive level sensors.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.476-482
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• 2009

This paper describes the development of capacitive sensor for the diagnosis of liquid dielectrics, which is widely used as the electrical insulating oil of transformer, circuit breaker, cable and etc. To survey the dielectric properties of the virgin and aged electrical insulating oils, we utilized the highly precise measuring system, using the principle of cross capacitance. The measured properties were used to determine the design factors of the sensor. Then the factors were optimized with the help of computational analysis. To evaluate diagnosis by the sensor, we performed accelerated thermal aging test about electrical insulating oils. The condition of aged specimens were investigated by measurements of relative permittivity i.e. capacitance change by capacitive sensor. And to evaluate the hysteresis characteristics with the change of temperature, we constructed a testing system, which was composed with vacuum drying oven, oil chamber and measuring instruments, such as LCR meter, MUX and so forth. Through the results of this investigation, we confirmed the superior characteristics of the newly developed sensor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.85-89
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• 2008

An objective of this paper is to develop a partial discharge (PD) measurement device for monitoring gas insulated switches installed in power distribution system. A capacitive voltage probe was studied and designed to detect PD pulse without an electrical connection. The PD measurement device consists of the capacitive voltage probe attached outside of a bushing, a coupling network which attenuates AC voltage by 270 dB, and a low noise amplifier with the gain of 40 dB in ranges of 500 kHz${\sim}$20 MHz. The sensitivity of the prototype device calculated by a calibrator was 1.98 m V /pc. An application experiment was carried out in a 25.8 kV gas insulated switch and the peak pulse of 76.7 pC was detected. From the experimental results, it is expected that the PD measurement device can be applied to online monitoring system of gas insulated switches.

• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.42-45
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• 2015

The ability to take electrocardiographic measurements while performing our daily activities has become the people-choice for modern age vital sign sensing. Currently, wet and dry ECG electrodes are known to pose threats like inflammations, allergic reactions, and metal poisoning due to their direct skin interaction. Therefore, the main goal in this work is to implement a very small ECG sensor system with a capacitive coupling, which is able to detect electrical signals of heart at a distance without the conductive gel. The aim of this paper is to design, implement, and characterize the contactless ECG electrodes. Under a careful consideration of factors that affect a capacitive electrode functional integrity, several different sizes of ECG electrodes were designed and tested with a pilot ECG device. A very small cotton-insulated copper tape electrode ($2.324cm^2$) was finally attained that could detect and measure bioelectric signal at about 500 um of distance from the subject's chest.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.858-865
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• 2008

In this paper, Capacitive Telemetry RF Sensor System using Recursive Least Square (RLS) algorithm was proposed. General Telemetry RF Sensor System means that it should be "wireless", "implantable" and "batterless". Conventional Telemetry RF Sensor System adopts Integrated Circuit type, but there are many defects like complexity of structure and the limitation of large power consumption in some cases. In order to overcome these disadvantages, Telemetry RF Sensor System based on inductive coupling principle was proposed in this paper. Proposed Telemetry RF Sensor System is very simple because it consists of R, L and C and measures the changes of environment like pressure and humidity in the type of capacitive value. This system adopted RLS algorithm for estimation of this capacitive parameter. For the purpose of applying RLS algorithm, proposed system was mathematically modelled with phasor method and was quasi-linearized. As two parameters such as phase and amplitude of output voltage for estimation were needed, Phase Difference Detector and Amplitude Detector were proposed respectively which were implemented using TMS320C2812 made by Texas Instrument. Finally, It is verified that the capacitance of proposed telemetry RF Sensor System using RLS algorithm can be estimated efficiently under noisy environment.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.840-845
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• 2010

In this paper, short-wavelength transmission line employing periodically arrayed capacitive devices (PACD) structures were developed for application to a development of miniaturized on-chip passive components on GaAs monolithic microwave integrated circuit (MMIC). The transmission line employing PACD structure showed a wavelength much shorter than conventional microstrip line. Concretely, the wavelength of the transmission line employing PACD structure was 8 % of the conventional microstrip line on GaAs substrate at 5GHz. And It was 38% of the microstrip line employing PPGM at 5GHz. It was recognized that the basic characteristics of the transmission line employing PACD structure were investigated for application to the miniaturized passive on-chip components.