• Title/Summary/Keyword: Electrical conductance

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Stability of the Cable-in-Conduit Conductors (CIC 초전도 도체의 안정성)

  • 류경우
    • Electrical & Electronic Materials
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    • v.10 no.9
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    • pp.895-900
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    • 1997
  • A Quench in cable-in-conduit (CIC) conductors is often initiated by a disturbance such as strand motion that generates a highly localized normal zone in a strand or a few strands of the CIC conductors. The localized normal zone causes current and heat transfer between a disturbed strand and neighboring strands. Electrical and thermal contact characteristics between strands thus have an effect on the transient stability of the CIC conductors. In this paper the effect of contact characteristics between strands on the CIC conductor stability is presented based on the measured heat transfer characteristics of supercritical helium (SHe) for the local heating. The quench and recovery processes of the strands for the abrupt and highly localized disturbance are analyzed at the boundary between quench and recovery.

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High-efficiency Organic Light-emitting Diodes(OLEDs) with optimized multilayer transparent electrodes

  • Yun, Chang-Hun;Cho, Hyun-Su;Yoo, Seung-Hyup
    • Journal of Information Display
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    • v.11 no.2
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    • pp.52-56
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    • 2010
  • High-efficiency organic light-emitting diodes (OLEDs) based on multilayer transparent electrodes (MTEs) are reported. The dielectric/metal/dielectric (DMD) multilayer electrode based on a thin silver layer achieved high sheet conductance as small as $6{\Omega}/sp$ and a tuning capability in the optical and electrical properties by engineering the inner and outer dielectric layers. In the conventional normal bottom-emitting structure, a DMD-based OLED can be fabricated with 90% higher forward luminous efficiency and 30% higher external quantum efficiency (EQE) compared to ITO-based devices. Special attention was paid to the optimization method of such MTE structure considering both the injection and optical structures.

Power Quality Assessment and PSCAD/EMTDC Modeling of Grid-Connected PV System (계통연계형 태양광발전시스템의 PSCAD/EMTDC 모델링 및 전력품질 평가)

  • Seol, Jae-Woong;Jang, Jae-Jung;Kim, Jin-O
    • Proceedings of the KIEE Conference
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    • 2006.07b
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    • pp.1227-1228
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    • 2006
  • This paper presents the results of a grid-connected photovoltaic(PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that can occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

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Power Quality Assessment and PSCAD/EMTDC Modeling of Grid-Connected PV System (계통연계형 태양광발전시스템의 PSCAD/EMTDC 모델링 및 전력품질 평가)

  • Seol, Jae-Woong;Jang, Jae-Jung;Kim, Jin-O
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1687-1688
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    • 2006
  • This paper presents the results of a grid-connected photovoltaic (PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that tan occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

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ANN-based Maximum Power Point Tracking of PV System using Fuzzy Controller (퍼지 제어기를 이용한 PV 시스템의 ANN 기반 최대전력점 추적)

  • Ko, Jae-Sub;Chung, Dong-Hwa
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.2
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    • pp.27-32
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    • 2015
  • A maximum power point tracking (MPPT) algorithm using fuzzy controller was considered. MPPT method was implemented based on the voltage and reference PV voltage value was obtained from Artificial Neural Network (ANN)-model of PV modules. Therefore, measuring only the PV module voltage is adequate for MPPT operation. Fuzzy controller is used to directly control dc-dc buck converter. The simulation results have been used to verify the effectiveness of the algorithm. The proposed method is compared with conventional PO(perturbation & observation), IC(Incremental Conductance) method. The nonlinearity and adaptiveness of fuzzy controller provided good performance under parameter variations such as solar irradiation.

Thermodynamic Parameters for Micelle Formation of Dodecylpyridinium Chloride (Dodecylpyridinium Chloride의 micelle 形成의 熱力學變數)

  • Han, Man-Un
    • Journal of the Korean Chemical Society
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    • v.10 no.2
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    • pp.103-108
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    • 1966
  • The effect of temperature on the critical micelle concentration of dodecylpyridinium chloride has been determined by electrical conductance method over the range from $5^{\circ}C\;to\;50^{\circ}C$. The values of the change in heat content, ${\Delta}H_m$, and the other thermodynamic parameters have been estimated using the equation of temperature dependence on the critical micelle concentration for the same temperature range. The significance of these thermodynamic quantities and their relations to the various current theories of micelle forming processes were discussed.

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대전지역 약수의 수질특성과 관리방안

  • 정찬호;김은지;문병진
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.09a
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    • pp.15-18
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    • 2001
  • Sixty natural springs and wells used as community facilities for drinking water are developed along mountain climbing way of suburban area and residential area in Daejeon City. In this study, the seasonal variation of their water quality and hydrochemical characteristics were investigated. Some natural springs are vulnerable to bacilli contamination because of their short residence time and shallow circulation in subsurface environment. The waters show hydrochemical types of Ca-HCO$_3$ and Na-HCO$_3$, and are characterized by low electrical conductance and weak acidic pH.

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A Study of MPPT algorithm for Low-insolation (저일사강도에서 MPPT를 동작시키기 위한 알고리즘 연구)

  • Kim, Ki-Hyun;Yu, Gwon-Jong;Jung, Young-Seok;Kim, Young-Seok
    • Proceedings of the KIEE Conference
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    • 2001.04a
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    • pp.473-475
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    • 2001
  • This paper proposed a MPPT ( Maximum Power Point Tracking) control algorithm for PV(Photovoltaic) array based on a modified constant voltage control MPPT algorithm at low-insolation. This method which combines a IncCond(Incremental Conductance) and a constant voltage control algorithm. In contrast to the typical conventional MPPT algorithm, the proposed method have been obtained high efficiency and good performance. The proposed algorithm is verified through simulation result. In order to confirm the availability of the scheme, a simulation used PSIM and ACSL software tool.

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A Study of the Ionic Association of the Substituted N-Methyl Pyridinium Iodides (I). N-Methyl Pyridinium Iodide in Ethanol-Water Mixture

  • Jee, Jong-Gi;Kwun, Oh-Cheun
    • Bulletin of the Korean Chemical Society
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    • v.5 no.1
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    • pp.44-49
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    • 1984
  • The ionic association constant (K) of N-methyl pyridinium iodide (NMPI) ion in several ethanol-water mixtures were determined by the combination of UV spectroscopy and conductance measurements using the Shedlovsky function as a correction factor. The measurement of electrical conductance and UV absorption were performed in 95, 90, 80 and 60 volume percentages of ethanol in the solvent mixture at 15, 25, 35 and 45 $({\pm}0.1)^{\circ}C$. The ion size parameter $(r_A+_D-)$ and the dipole moment $({\mu}_A+_D-)$ of NMPI ion were obtained from he linear plots of ln K vs. (1/D) and (D-1)/(2D+1), respectively. These ${\mu}_A+_D-$ values were in good agreement with the values of transition moment calculated from the equation, ${\mu}_{nm}=6.5168{\times}10^{-2}{\times}({\varepsilon}_{max}{\frac{\bar{\nu}_{\frac{1}{2}}}{\bar{\nu}_{max}})^{\frac{1}{2}}$ (Debye) which we have derived. The thermodynamic parameters indicate (1) that the water dipoles have an ordered rearrangement around the dipolar NMPI ions rather than the configuration existing in bulk free waters; and (2) that the equilibrium state between NMPI ion and its component ions are controlled by entropy.