• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.243-247
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• 2014

In this paper, we design two types of the sensor module to measure the partial discharge causing failures and electric fires for power incoming/distributer. And evaluate the performance thereof. Analyze the correlation of the phase current and the partial discharge and overheating. Proposes to apply the stability index by utilizing the analyzed information and use in order to prevent the failure or electrical fire of the power incoming/distributer.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.12
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• pp.40-48
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• 1998

An offset compensation scheme for rail-to-rail CMOS op-amps with complementary input stages is presented. Two auxiliary amplifiers are used to compensate for the offsets of NMOS and PMOS differential input stages, and ping-pong control is employed for continuous-time operation. A 3V offset-compensated rail-to-rail CMOS op-amp has been designed and fabricated using a 0.8$\mu\textrm{m}$ single-poly, double-metal CMOS process. Measurement results show that offsets are reduced about 20 times by this scheme.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.253-254
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• 2006

this paper suggest a new space vector PWM modulation method with short processing time which does not need idenfication of nearest three vectors(NTV) and duty calculation for each vector. The suggested PWM method makes mean value of phase voltage to be same as reference during every modulation period by use of a triangle in small hexagon on multi-level vector space. This paper described the suggested modulation method can be successfully applied to the space vector modulation use of multi-level inverter by computer simulations and experiments.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.157-161
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• 2001

The observe relaxation phenomena and freezing behavior in Pb(Mg/sub ⅓/Nb/sub ⅔/O₃, relaxor ferroelectrics, weak electric-field properties as well as strong electric-field properties were investigated. The temperature dependence of the dielectric properties obtained using the low electric-field of 1 V/w was investigated. The dielectric properties obtained from the slope of the dielectric hysteresis loop and the temperature dependence of the pyroelectric properties were also investigated. When fitting all the experimental data with the Vogel-Filcher relation, a close agreement between the experimental data and equation was observed. The freezing temperature could be consistently calculated by the various methods.

• Proceedings of the KSR Conference
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• 2006.11a
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• pp.171-180
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• 2006

The EMS system requires a very delicate suspension control to maintain constant air-gap between the magnet and the guide-way rail. To maintain a constant air-gap with attraction force, the EMS system dynamics is changed according to uncertainties and disturbances, and it also requires reliability against component failures. Since uncertainties and component failures are frequently caused in EMS system, it is very important to develop the robust and reliable control system. In this paper, we consider the design problem for robust and reliable controller in the presence of uncertainties and component failures.

• Journal of Ginseng Research
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• v.20 no.1
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• pp.23-29
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• 1996

The effect of ginseng glycosides and their aglycones on the thermodynamic characteristics of membranes from dipalmitoylphosphatidylcholine (DPPC) was investigated. Total saponins (TS) from Korean red ginseng, Panax ginseng C.A. Meyer, interacted with the Eel Phase of lipid in the Polar region and did not penetrate the deeper glycerol backbone of lipid molecule. From the all investigated components of TS (aglycons and ginsenosides), only 20-(S)-panaxadiol (PD) had an effect similar to TS. High concentration of TS penetrated in hydrophobic Cl-C8 region. The presence of cholesterol did not influence the interaction of TS with DPPC. An elimination of transition, however, took place at 10~100 $\mu\textrm{g}$/ml of TS. DPPC had a low ability to interact with cholesterol (CHL) as compared with other lecithins except ethanolamine. From our results, only TS and PD, at high concentrations (100 mol%), influenced the phase transition of mixture of DPPC:CHL.

• Textile Coloration and Finishing
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• v.15 no.2
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• pp.68-75
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• 2003

In this work, ultrafiltration(UF) membranes were prepared using polyethersulfone(PES). The polymer was dissolved in various solvent, such as N, N-dimethyl formamide(DMF), N,-dimethyl acetamide (DMAc), N,N-dimethyl sulfoxide(DMSO) and N-methyl-2- pynolidone(NMP). Each polymer solution was casted on the glass plate, and immersed into non-solvent bath. In this way finely porous UF membranes were prepared by phase inversion method. The cross sectional structure of PES membrane was asymmetric which was consist of sponge-like sublayer, finger-like toplayer, and active skin layer. From the solute rejection experiments, the molecular weight cut off of the prepared membrane in various solvent was evaluated 10,000 for DMF, 30,000 for DMAc, 50,000 for DMSO, and 10,000 for NMP respectively.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2004.11a
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• pp.39-39
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• 2004

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.312-317
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• 2007

최근 다수의 태양광 발전기가 배전계통에 연계되고 있으며 특히, 특정지역을 중심으로 대규모의 태양광발전 단지가 구성되어 배전계통에 연계되고 실정이다. 본 논문에서는 순천에 구축된 l000KW급 태양광발전소의 계통해석영향을 분석하기 위하여 PSCAD/EMTDC 툴을 이용하여 모델링 하고 태양광발전이 연계된 배전계통 조류해석과 태양광 발전의 출력에 의한 22.9KV 배전계통의 전압변동을 시뮬레이션 하였으며, 태양광발전에 따른 역조류에 의한 배전계통 전압변동을 분석하였다. 또한, 태양광발전기의 배전계통 연계 전,후의 배전선로의 임의의 지락고장 모의로 태양광발전기가 고장전류에 미치는 영향 분석과 태양광 발전이 양호, 불량한 경우에 대한 상전압, 고조파 전류, 역률 등의 측정결과에 의한 전력품질을 분석 하였다.

• Progress in Superconductivity
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• v.11 no.2
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• pp.112-117
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• 2010

We examine phase transition of the spin density wave and $\pi$ phase shifted superconductivity in the Fe pnictide superconductors. The phase diagram is described in the plane of the temperature T and the doping x with the combination of Ginzburg-Landau expansion of the free energy near the multi-critical temperature $T_c$ and the self-consistent numerical iterations of the gap equations. The phase separation or coexistence is determined by computing the 4-th order terms of the free energy which is confirmed by the numerical calculations. We can show the phase coexistence when the spin density wave is incommensurate. And the first order phase transition is observed near the boundary between commensurate and incommensurate spin density wave.