• Title, Summary, Keyword: Internal voltage

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Change of Internal Resistance of OLED Devices during Operation

  • Lee, Soon-Seok;Hwang, Hak-Eun;Lim, Sung-Kyoo
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1443-1446
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    • 2007
  • The luminance and operating voltage were measured during OLED operation for the purpose of analyzing the efficiency and change of internal resistance. The half lifetime of OLED was affected by degradation of OLED due to heat generated by ambient temperature and self heating. The operating voltage constantly increased due to the increase of internal resistance. The half lifetime of OLED driven by constant current source was found to be longer than that of the OELD driven by constant voltage and the reasons were clearly explained in this paper.

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Study on Testing Enclosed low-voltage switchgear and controlgear assemblies Under conditions of arcing due to internal faults (내부고장으로 인한 아크상태의 저압배전반 시험방법 동향 고찰)

  • Kim, Sun-Ho;Kim, Sun-Koo;Roh, Chang-Il;Jung, Heung-Soo;Kim, Won-Man;Lee, Dong-Jun
    • Proceedings of the KIEE Conference
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    • pp.927-928
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    • 2007
  • Recently IEC has made considerations on testing Enclosed low-voltage switchgear and controlgear assemblies under conditions of arcing due to internal faults. This paper will make a study on testing Enclosed low-voltage switchgear and controlgear assemblies under conditions of arcing due to internal faults that is suggested by IEC.

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A Study on the P-I, I-V Characteristics of PEMFC (PEM 연료전지의 전력-전류, 전압-전류 특성에 관한 연구)

  • Jung, You-Ra;Choi, Young-Sung;Hwang, Jong-Sun;Lee, Kyung-Sup
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.4
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    • pp.557-562
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    • 2009
  • Recently, researchers are developing a new, clean, renewable and sustainable energy to the industrial areas and the residential areas. Solar cell and fuel cell energy are presented in this paper. The paper shows the P-I and I-V characteristics of fuel cells which are connected in parallel and series. And the voltage drop of internal resistance of the fuel cell decreases with the increasing of the current of the fuel cell. A voltage drop at the internal resistance is increased according to the current, thus the terminal voltage is decreased. The internal resistance is calculated $0.3[\Omega]$ from maximum power transfer condition.

Dynamic Transient Phenomena of a Proton Exchange Membrane Fuel Cell

  • Lee, Ying;Choi, Yong-Sung;Zhang, You-Sai;Lee, Kyung-Sup
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.7
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    • pp.530-533
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    • 2010
  • The proton exchange membrane fuel cell (PEMFC) holds great promise of clean power. However, in practical applications which use the PEMFC as the power source, the output voltage from the fuel cell undergoes a transient response especially during acceleration and deceleration. This paper presents the relationships between the charge curves of the internal voltage rise, discharge curves of the internal voltage drop, the voltage with a time constant $V_{\tau}$ and finally, the load and time constant $\tau$ of $FC_1$ and $FC_2$, connected both in series and in parallel.

A Voltage-Down Converter for Low-Voltage SoC

  • Yi Won-jae;Lee Se-chul;Kang Tae-kyoung;Lim Gyu-Ho;Huh Young;Park Mu-Hun;Kim Young-Hee
    • Proceedings of the IEEK Conference
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    • pp.66-69
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    • 2004
  • This work is the study of Voltage-Down Converter used as internal supply voltage having large current driving and stable voltage level at any variation of process, voltage, and temperature(P.V.T). It converts VDD(external supply voltage) into $V_{1NT}(internal\;supply\;voltage).$ From the simulation results, a new Voltage-Down Converter has large current driving and a little stand-by current under lower supply voltage than conventional circuit. And bad characteristic of VINT, peaking, was eliminated. Start-up circuit for BGR is also added to one circuit, which consumes less current dissipation than convention circuit

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The Characteristics of Superposed Ozonizer using Three-Phase Voltage (3상전압을 이용한 중첩방전형 오존발생기의 특성)

  • Kim, Yeong-Hun;Chun, Byung-Joon;Song, Hyun-Jig;Youn, Young-Dae;Lee, Kwang-Sik
    • Proceedings of the KIEE Conference
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    • pp.2259-2261
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    • 1999
  • In this paper, an ozonizer, which can generate individual and superposed silent discharge, using three-phase voltage has been designed and manufactured. The ozonizer consists of 3 electrodes(Central Electrode, Internal Electrode and External Electrode) and 2 gaps(gap between Central Electrode and Internal Electrode, gap between Internal Electrode and External Electrode). Ozone is generated according to voltage supplying method to each electrode by individual silent discharge and three-phase superposed discharge. The characteristics of ozone generation were investigated with variation of discharge power and the quantity of supplied gas($O_2$). In case of individual silent discharge, the maximum values of ozone concentration, ozone generation and ozone yield were obtained between internal electrode and external electrode, and its values were 2300[ppm], 570[mg/h] and 745[g/kWh] respectively. Each maximum values was 5039[ppm], 1773[mg/h] and 851[g/kWh] respectively, when three-phase superposed silent discharge was employed. Therefore, characteristics of ozone generation with three-phase voltage are improved compared with single-phase voltage because silent discharge is generated continuously.

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ELID characteristics of internal grinding wheel by using M/C (M/C에 사용되는 내면연삭 휠의 ELID 특성)

  • Kim, S. H.;Bang, J. Y.;Ji, H. G.;Choi, H.;lee, J. C.;Cheong, S. H.;Jae, T.J
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.999-1002
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    • 1997
  • In this study, in order to set ELID conditions in the internal grinding wheel, the characteristics with the variations of grit size, output voltage and peak current were examined by using conventional machining center(M/C) equipped with electrolytic in-process dressing(EL1D). The initial working voltage was lowered and the working current was high with increasing grit size. The insulating layer thickness increased, as the final voltage increased with the output voltage and peak current. The initial wear rate of the wheel machined with ELID were measured indirectly by using surface roughness tracer. The initial wear rate of the wheel with ELID increased along with high grit size. In case that the grit size with ELID was low, the output voltage and peak current had to be increased to increase the insulating layer thickness. In case of the high grit size, the output voltage and the peak current were established low, which made the insulating layer thickness decreased.

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Improvement of Transient Characteristics of Brush-less Type Synchronous Generator for Emergency Driven by Internal-Combustion Engine (내연기관 구동 비상용 브러시리스형 동기발전기의 과도특성 개선)

  • An, Young-Joo
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.65 no.4
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    • pp.268-272
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    • 2016
  • A brush-less type synchronous generator is driven by an internal-combustion engine that is used for emergency source. This kind of generator has to maintain output voltage in a range of some degree under the abrupt load irregular conditions such as a full load trip. This paper suggests a suppression method of increasing the output voltage over the rating. Automatic voltage regulator detects excessive rising of output voltage of the generator and supplies the signals to a switch installed in the rotating exciter through the photo-coupler. The current of main field rapidly decreases by additional resistor of the main filed circuit. Therefore, the output voltage of the generator is maintained effectively. The experimental results verified that the excessive value of the output voltage is limited in the range of 7% of the rated voltage.

Analysis of Internal Energy Pulsation in MMC System According to Offset Voltage Injection with PWM Methods (PWM 방식을 이용한 옵셋 전압 주입에 따른 MMC 시스템 내부 에너지 맥동 분석)

  • Kim, Jae-Myeong;Jung, Jae-Jung
    • Journal of IKEEE
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    • v.23 no.4
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    • pp.1140-1149
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    • 2019
  • In general, there are various pulse width modulation(PWM) methods simply using the offset voltage injection in voltage source converter(VSC). In accordance with the AC side voltage synthesis method with the offset voltage, DC side voltage utilization factor in VSC is changed. Also, this can apply equally to the MMC system. In other words, if the DC side capacity of the high voltage DC(HVDC) transmission system is determined, the maximum reactive power which can be supplied to the AC side can be changed according to the applied output voltage synthesis method with the offset voltage. In this paper, the leg energy pulsation in MMC system according to the AC side output voltage synthesis method with offset voltage which several representative PWM are applied to are mathematically analyzed and compared with each other. Finally, the above results are verified by simulation emulating the 400MVA full-scale MMC system to determine the consistency of the mathematical analysis.

A Study on the Design of the Voltage Down Converter for Low Power, High Speed DRAM (DRAM의 저전력, 고속화에 따른 VDC 설계에 관한 연구)

  • 주종두;곽승욱
    • Proceedings of the IEEK Conference
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    • pp.707-710
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    • 1998
  • This paper presents a new voltage down converter(VDC) for low power, high speed DRAM. This VDC Consists of RVG(Reference Voltage Generator) and Driver Circuit. And it is independent of temperature variation, and Supply Voltage. Using weak inversion region, this RVG dissipates low power. Internal Voltage Source of this VDC is stable in spite of high speed operation of memory array. This circuit is designed with a $0.65\mu\textrm{m}$ nwell CMOS technology. In HSPICE simulation results, Temperature dependency of this RVG is $20\muV/^{\circ}C,$ supply voltage dependency is $\pm0.17%,$ $VCC=3.3V\pm0.3V,$ and current dissipation is $5.22\muA.$ Internal voltage source bouncing of this VDC is smaller than conventional VDC.

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