• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.65-68
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• 2001

본 연구에서는 코움 드라이브에 비해 구동력은 크고 평행 판 구동 방식에 비해서는 선형 특성이 우수하며 안정된 구동거리가 증가하는 특성을 갖는 새로운 정전력(electrostatic force) 구동 방식을 제안한다. 운동 전극과 고정 전극을 기울어지게 배치하여 전극 면에 평행한 정전력 $F_x$와 전극 면에 수직인 정전력 $F_y$의 합력 $F_e$ 방향으로 전극을 운동시킴으로써 정전력의 방향과 전극의 운동 방향을 일치시킨다. 제안된 구동방식의 정전력 모델을 이용한 해석 결과 코움 드라이브에 비해서는 구동력이 50 % 이상 크며 평행 판 구동에 비해서는 안정된 구동 거리가 10 - 30 % 이상 증가하는 구동 특성을 얻을 수 있었다. 제안된 구동방식을 이용하여 HDD의 트랙 방향 저장 밀도를 증가시키기 위한 듀얼스테이지 서보(dual-stage servo)에 사용 될 마이크로 액츄에이터 (microactuator)를 설계하고 SoG(Silicon on Glass) 공정을 이용하여 제작하였다.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.5
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• pp.401-412
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• 2013

The paper is to study on the simulation of the micro/macroscale thermo-electrochemical model of a single cell of anode-supported SOFC with direct internal reforming. The coupled heat and mass transport, electrochemical and reforming reactions, and fluid flow were simultaneously simulated based on mass, energy, charge conservation. The micro/macroscale model first calculates the detailed electrochemical and direct internal reforming processes in porous electrodes based on the comprehensive microscale model and then solve the macroscale processes such as heat and mass transport, and fluid flow in SOFCs with assumption of fully-developed flow in gas channel. The simulation results evaluate the overall performance by analyzing distributions of mole fraction, current density, temperature and microstructural design in co/counter flow configurations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.45-49
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• 2006

Electrochemical hydrogenation/dehydrogenation properties were studied for a single particle of a Mm-based(Mm : minh metal) hydrogen storage alloy($MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$) for fuel cell and Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and the potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-9}\;and\;10^{-10}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process. Compared with the conventional composite film electrodes, the single particle measurements using the microelectrode gave more detailed, true information about the hydrogen storage alloy.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.275-278
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• 2002

본 논문에서는 한국의 전파환경을 도시 계획법에서 지정한 지역세분을 기초로 4개의 대분류와 8개로 소구분하여 Kor-231 모델을 제안하였다. 전파전파 특성을 측정하기 위해 슬라이딩 코릴레이션 기법을 이용한 대역확산 송${\cdot}$수신 방식으로 구현하여 수신전력, 평균 초과지연 그리고 RMS 지연확산을 가장 도시계획적으로 개발된 공업 지역과 주거지역에서 직선 도로에 마이크로셀을 배치하여 도로를 따라 진행하는 LOS와 건물들로 둘러쌓인 N-LOS에서 측정된 데이터를 분석하여 한국의 전파환경에서 잘 적용됨을 확인 하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.2
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• pp.241-246
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• 1986

A new method of on-line monitoring of spot weld quality is proposed by analysing weld votage signal. Weld voltage signal has been modeled by autoregressive model which is suitable for on-line modeling scheme, and order of the model is determined by F-test. From the chosen model, strength. Upon experimental results, it has been shown that fundamental frequency dispersion of weld voltage can be used as a good parameter like maximum thermal expansion in on-line monitoring of spot weld quality. Microcomputer implementation of the proposed monitoring method is also developed and presented.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.372-377
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• 2001

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model of a piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate the effective properties of fiber composites are extended to apply to the PFPMIDE model. The new model is validated comparing with available experimental data and other analytical results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.46-52
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• 2006

The effects of surface treatment on the hydrogen storage properties of a $Mg_2Ni$ alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle in a KOH aqueous solution. It was found that the hydrogen storage properties of $Mg_2Ni$ at room temperature were improved by the surface treatment with a nickel plating solution. The sodium salts(sodium phosphate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen charge/discharge capacity at room temperature as high as about 150[mAh/g] from the original value of 17[mAh/g]. Potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-8}{\sim}10^{-9}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.109-114
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• 2013

The biological active points (BAP) are known as low resistance spots or good electro-permeable points. In this paper, a new method for BAP detection using the bio-impedance measurement system based on the adaptive frequency tracking filter (AFTF) and the transition event detector is presented. Also, the microcontroller process continuous time demodulation of the modulated signal by multi frequency components using the AFTF. The transition event detector based on the phase space method is applied about each frequency using the BAP equivalent model which is proposed.