• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.636-640
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• 2009

태양광발전과 같은 분산형전원이 기존의 어떤 보호협조체제하의 배전선로에 도입될 경우는 계통에 대한 역 조류에 의해 사고 시 고장 구간의 분리 및 선로재구성에 따른 차단기 및 개폐기 제어알고리즘, 그리고 순시정전 시 분산형전원의 기동정지, 개폐기의 기능, 차단용량 등에 악영향을 끼칠 우려가 다분히 있다. 또한, 사고 시 일시적으로 분리된 건전구간 내에 분산형전원이 존재하여 그 구간내의 부하와 평형을 이루며 운전되고 있는 경우가 있을 수 있는 데, 이 경우는 인체 및 전기설비에 위험을 초래하게 될 뿐만 아니라 사고의 신속한 복구에도 저해의 요인이 된다. 특히, 태양광발전이 배전선로에 연계되어 운전되는 경우, 동일 뱅크의 타 배전선로에서 사고가 발생하면 태양광발전이 연계된 건전한 배전선로의 보호협조기기(리클로져)가 오동작하는 사고가 발생하는 경우가 실 계통에서 빈번하게 발생하고 있다. 이에 의하여 건전한 선로의 부하가 정전을 경험하는 심각한 문제점이 발생한다. 따라서 본 논문에서는 이론적인 계산식인 대칭좌표법을 이용하여 모델링과 시뮬레이션을 수행하여, 상기의 보호기기의 오동작 메카니즘과 문제점을 분석하고, 이에 대한 개선 방안을 제시하였다.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.403-408
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• 2021

In this study, a thin and flexible planar supercapacitor (PSC) was fabricated by coating polyaniline (PANI) on a screen-printed carbon electrode. Carbon ink was coated onto the flexible polyethylene terephthalate using a screen-printing method; subsequently, a thin film of PANI was coated onto the carbon surface using a dilute polymerization method. A thin flexible PANI electrode in an interdigitated structure was assembled with a polymer gel electrolyte that resulted in planar-shaped supercapacitor (PSC) devices. The as-obtained PANI/PSC was very thin and flexible, exhibiting a high areal capacitance of 409 µF/cm was obtained at a rate of 10 mV/s. This capacitance retains 46% of its original value at 500 mV/s. The flexible PANI/PSC exhibited an excellent capacitance retention of 82% even under bent states of 180° and 100 repetitive bent cycles.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.2 s.25
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• pp.1-6
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• 2007

When the water content within concrete swells, diverse problems occur such as drop in durability. Due to this reason, a change is being managed in the unit water contents by using electric capacity measurements, high frequency heating methods, and unit-volume mass measurements, which are methods of measuring the unit water contents. Particularly, Japan is prescribing the guideline of management on a change in unit water content unit quantity $({\pm}10,\;15,\;20kg//m^3,\;etc.)$. However, the guideline of Japan dose not consider a fall in durability, and is decided on the value of pass-fail criteria by random fabrication errors and measurement errors. Consequently, this study was aimed to investigate the influence of a change In water content within concrete due to an addend caused by management error and to an artificial addend, upon drop in durability.

• Journal of the Korean Electrochemical Society
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• v.8 no.2
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• pp.99-105
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• 2005

In this study, the $PPy/CLO_4$ and PPy/PVS composite electrodes were prepared at various polymerization potential by incorporating electrolyte anions of different anion size during constant potential polymerization. The reulting Polypyrrole surfaces were inspected by SEM, and their electrochemical Properties were investigated with CV and ac impedance method. The results of electrochemical analysis were suggested that anion for $PPy/CLO_4$ electrode and cation fir PPy/PVS electrode were transferred during redox reaction. As constant potential of polymerization was increased, the charge transfer resistance of $PPy/CLO_4$ and PPy/PVS was decreased and the electric double layer capacitances of $PPy/CLO_4$ was higher than that of PPy/PVS. The change of PPy/PVS surface was relatively smaller than that of $PPy/CLO_4$ according to electropolymerization potential.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.439-443
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• 2016

In this report, $MnO_2$ nanoparticle-deposited functionalized graphene sheets were prepared and their superior electrochemical performances were demonstrated by cyclic voltammetry, galvanostatic charge-discharge, and impedance analysis. Ionic liquids were employed to functionalize the surface of reduced graphene oxides (RGOs), leading to prevention of the aggregation of RGO sheets and abundant growth sites for deposition of $MnO_2$ nanoparticles. As-prepared $MnO_2/RGO$ nanocomposites were characterized using scanning electron microscope, transition electron microscope, X-ray photoelectron spectroscopy, and X-ray diffraction. Electrochemical properties of $MnO_2/RGO$ electrode were evaluated using $Na_2SO_4$ electrolyte under a three-electrode system. The $MnO_2/RGO$ electrode showed a high specific capacitance (251 F/g), a high rate capability (80.5% retention), and long-term stability (93.6% retention).

• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.64-70
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• 1999

The inrush current of transformer can flow when the overvoltage caused by surge or external faults is applied. In this paper, an algorithm for the calculation of this inruch current is proposed. The capacitances of windings are precalculated by using 3 dimensional FEM and are appended to circuit of the transformer. And transient characteristics of the transformer are analyzed by axisymmetric FEM which is coupled magnetic field of transformer and circuit of transformer. When a transformer encounters abnormal voltage, using the proposed method, internal magnetic field of transformer, voltages and currents of windings are calculated.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.1-11
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• 2002

In this paper, new simple method for the calculation of depletion region under complex geometry and general purpose numerical simulator that could handle this were developed and applied in the analysis of SCM with nanoscale tip, which is a promising tool for high resolution dopant profiling. Our simple depletion region seeking algorithm alternatively switches material of elements to align ionized element boundary with contour of zero potential. To prove the validity of our method we examined whether our results satisfy the definition of depletion region and compared those with known values of un junction and MOS structure. By modeling of capacitance based on the shape of depletion region and potential distribution, we could calculate the CV curve and dC/dV curve between silicon substrate and nanoscale SCM tip.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.55-60
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• 2017

This paper is proposed on the transmit Method Finger-Printer Scanning of Mutual Capacitance Touch Screen Panel Using Differential Pulse for improving the security of computer information. This system is composed of differential pulse generator and Ring-Counter, also Supply voltage is 5V. this system generates the Pulse wave which is composed of In-Phase and Out of Phase at 1MHz while period of 2m/s. it is designed and be able to operate four channels. overall power consumption is approximately 78.08nW. This prototype is implemented in 0.25um CMOS Process and Chip area is $870um{\times}880um$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.304-307
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• 2004

As optical fiber communication grows, the fiber alignment become the focus of industrial attention. This greatly influence the overall production rates for the opto-electric products. We proposed multi-axis nano positioning stage for optical fiber alignment. This device has 3 DOF translation and sub nanometer resolution. This nano stage consist of 3 PZT-driven flexure stages which are stacked parallel. The displacement of it is measured with capacitance gauge and is controlled by computer-embedded main controller. The design process of flexure stage using FEM is proposed and the performance evaluation of this system is verified with experiments.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.218-220
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• 2007

유기박막트랜지스터(organic thin film transistor, OTFT)의 게이트 절연막으로 PVP(poly-4-vinylphenol) 물질을 이용하여 MIM (metal-insulator-metal) 구조의 캐패시터 소자를 제작하였다. 유기 절연층의 형성은 ITO/Glass 기판 위에 PVP를 용질로, PGMEA(propylene glycol monomethyl ether acetate)를 용매로 사용하였다. 또한 열경화성 수지인 poly(melamine-co-formaldehyde)를 사용하여 cross-linked PVP 절연막을 합성하여 스핀코팅법으로 소자를 형성하였다. 제작된 소자에 대해 절연막 두께에 따른 전기적 특성을 조사한 결과 300 nm 에서 500 nm로 두께가 증가할수록 누설전류는 10.69 nA 에서 0.1 nA 로 크게 감소하였다. 또한 캐패시터 소자의 정전용량은 300 nm 의 두께에서 1.05 nF 으로 500 nm 의 두께에서의 0.65 nF 과 비교하여 보다 양호한 특성이 나타났다.