• Title/Summary/Keyword: active diode

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Low-Power Cool Bypass Switch for Hot Spot Prevention in Photovoltaic Panels

  • Pennisi, Salvatore;Pulvirenti, Francesco;Scala, Amedeo La
    • ETRI Journal
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    • v.33 no.6
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    • pp.880-886
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    • 2011
  • With the introduction of high-current 8-inch solar cells, conventional Schottky bypass diodes, usually adopted in photovoltaic (PV) panels to prevent the hot spot phenomenon, are becoming ineffective as they cause relatively high voltage drops with associated undue power consumption. In this paper, we present the architecture of an active circuit that reduces the aforementioned power dissipation by profitably replacing the bypass diode through a power MOS switch with its embedded driving circuitry. Experimental prototypes were fabricated and tested, showing that the proposed solution allows a reduction of the power dissipation by more than 70% compared to conventional Schottky diodes. The whole circuit does not require a dedicated DC power and is fully compatible with standard CMOS technologies. This enables its integration, even directly on the panel, thereby opening new scenarios for next generation PV systems.

Diode Equivalent Parameters of Solar Cell

  • Iftiquar, Sk Md;Dao, Vinh Ai;Yi, Junsin
    • Current Photovoltaic Research
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    • v.3 no.4
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    • pp.107-111
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    • 2015
  • Current characteristic curve of an illuminated solar cell was used to determine its reverse saturation current density ($J_0$), ideality factor (n) and resistances, by using numerical diode simulation. High efficiency amorphous silicon, heterojunction crystalline Si (HIT), plastic and organic-inorganic halide perovskite solar cell shows n=3.27 for a-Si and n=2.14 for improved HIT cell as high and low n respectively, while the perovskite and plastic cells show n=2.56 and 2.57 respectively. The $J_0$ of these cells remain within $7.1{\times}10^{-7}$ and $1.79{\times}10^{-8}A/cm^2$ for poorer HIT and improved perovskite solar cell respectively.

The effect of a diode laser and traditional irrigants on the bond strength of self-adhesive cement

  • Tuncdemir, Ali Riza;Yildirim, Cihan;Ozcan, Erhan;Polat, Serdar
    • The Journal of Advanced Prosthodontics
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    • v.5 no.4
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    • pp.457-463
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    • 2013
  • PURPOSE. The purpose of this study was to compare the effect of a diode laser and traditional irrigants on the bond strength of self-adhesive cement. MATERIALS AND METHODS. Fifty-five incisors extracted due to periodontal problems were used. All teeth were instrumented using a set of rotary root canal instruments. The post spaces were enlarged for a No.14 (diameter, 1.4 mm) Snowlight (Abrasive technology, OH, USA) glass fiber reinforced composite post with matching drill. The teeth were randomly divided into 5 experimental groups of 11 teeth each. The post spaces were treated with the followings: Group 1: 5 mL 0.9% physiological saline; Group 2: 5 mL 5.25% sodium hypochlorite; Group 3: 5 mL 17% ethylene diamine tetra acetic acid (EDTA), Group 4: 37% orthophosphoric acid and Group 5: Photodynamic diode laser irradiation for 1 minute after application of light-active dye solution. Snowlight posts were luted with self-adhesive resin cement. Each root was sectioned perpendicular to its long axis to create 1 mm thick specimens. The push-out bond strength test method was used to measure bond strength. One tooth from each group was processed for scanning electron microscopic analysis. RESULTS. Bond strength values were as follow: Group 1 = 4.15 MPa; Group 2 = 3.00 MPa; Group 3 = 4.45 MPa; Group 4 = 6.96 MPa; and Group 5 = 8.93 MPa. These values were analysed using one-way ANOVA and Tukey honestly significant difference test (P<.05). Significantly higher bond strength values were obtained with the diode laser and orthophosphoric acid (P<.05). There were no differences found between the other groups (P> .05). CONCLUSION. Orthophosphoric acid and EDTA were more effective methods for removing the smear layer than the diode laser. However, the diode laser and orthophosphoric acid were more effective at the cement dentin interface than the EDTA, Therefore, modifying the smear layer may be more effective when a self-adhesive system is used.

Design and Fabrication of Ka-Band Active PIN Diode Limiter for a Millimeter Wave Seeker (밀리미터파 탐색기용 Ka 대역 능동 PIN 다이오드 리미터 설계 및 제작)

  • Yang, Seong-Sik;Lim, Ju-Hyun;Na, Young-Jin
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.2
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    • pp.220-228
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    • 2012
  • In this paper, we explained the design technique about Ka-band active limiter for protecting the receiver of a millimeter wave seeker. To implement low flat leakage power, we proposed the control circuit of active limiter to control limiter voltage with PRF(Pulse Repetition Frequency) signal and input power. This active limiter consisted of the conventional 2 stage passive limiter, a feedback circuit with a directional coupler, detector, non-inverting amplifier and over-current protection resistance. As the test result of the fabricated Ka-band limiter, it had 1 GHz bandwidth, 3.5 dB insertion loss at the small input power and -7.5 dBm flat leakage at the 4 W RF input power, respectively.

Improved performance of PEDOT:PSS/pentacene Schottky diode on EAPap (셀룰로우스 기반의 EAPap 작동기의 PEDOT_PSS/Pentacene를 이용한 Schottky diode 성능 개선)

  • Lim, Hyun-Kyu;Cho, Ki-Youn;Kang, Kwang-Sun;Kim, Jae-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.77-81
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    • 2007
  • Pentacene was dissolved in N-methyspyrrolidone (NMP) and mixed with poly(3,4-ethylenedioxythiophene), poly(styrenesulfonate) (PEDOT:PSS). The solution color changed from deep purple to intense yellow. As the dissolution time increased, visible absorption decreased and ultraviolet (UV) absorption increased. PEDOT:PSS or Pentacene-PEDOT:PSS was spin-coated to control the layer thickness. Three-layered Schottky diodes consisting of Al, PEDOT:PSS or PEDOT:PSS-pentacene, and Au with thickness of 300nm, respectively, were fabricated. The current densities of $4.8{\mu}A/cm^2$ at 2.5MV/m and $660{\mu}A/cm^2$ at 1.9MV/m were obtained for the Au/PEDOT:PSS/Al and Au/Pentacene-PEDOT:PSS/Al Schottky diodes, respectively. The current density of the Schottky diode was enhanced by about two orders of magnitude by doping pentacene to PEDOT:PSS.

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Fabrication and characteristic evaluation of microfluidics chip integrated OLED for the light sources (OLED광원이 집적화된 마이크로 플루이딕칩의 제작 및 특성 평가)

  • Kim, Young-Hwan;Han, Jin-Woo;Kim, Jong-Yeon;Kim, Byoung-Yong;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.377-377
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    • 2007
  • A simplified integration process including packaging is presented, which enables the realization of the portable fluorescence detection system. A fluorescence detection microchip system consisting of an integrated PIN photodiode, an organic light emitting diode (OLED) as the light source, an interference filter, and a microchannel was developed. The on-chip fluorescence detector fabricated by poly(dimethylsiloxane) (PDMS)-based packaging had thin-film structure. A silicon-based integrated PIN photo diode combined with an optical filter removed the background noise, which was produced by an excitation source, on the same substrate. The active area of the finger-type PIN photo diode was extended to obtain a higher detection sensitivity of fluorescence. The sensitivity and the limit of detection (LOD S/N = 3) of the system were $0.198\;nA/{\mu}M$ and $10\;{\mu}M$, respectively.

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Super Wide-Band AM Modulator (초광대역AM변조기)

  • 이충웅;고병준
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.9 no.4
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    • pp.1-6
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    • 1972
  • A super widely amplitude modulating AM modulator system, utilizing the impedance trasformation characteristics of transmission line is presented. The analyses and oscillograms obtained from the AM modulator systems using VHF tube, FET or VVC diode as an active element are added to verify the principle of the system.

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Performance improvement of a voltage source active filter (병렬형 전압원 능동필터의 성능개선)

  • Kang, Yu-Ri;Kim, Won-Ho;Rim, Geun-Hie
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.553-555
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    • 1994
  • Various nonlinear loads such as diode rectifiers, and phase controlled converters connected to at source cause harmonic pollutions in ac mains. Recently some filters have been proposed to minimize the potential problems. This study describes a method to improve the performances of a voltage source active filter. Two feedback loops are used in the scheme : one for reactive power compensation and the other for harmonic eliminations.

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Optical Bistable Device Using Poistive Electro-Optic Feedback (전기광학적 정궤환을 이용한 광쌍안정소자)

  • 이창희;김석윤;갑상영;이수영
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.1
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    • pp.94-100
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    • 1988
  • To improve the switching time of active optical bistable devices, we propose an active optical bistable device that consists of a diode laser, a transistor, and a photodetector. By implementing the proposed device we realize the optical bistable device with a 5 nanosecond switching time. This is the fastest switching time among the hybrid type optical bistable devices. It is also experimentally demonstrated that the proposed device may be used in an optical disc pick up.

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Planar Active Rectrodirective Array With Subharmonic Phase Conjugation Mixers

  • Kim Gi-Rae;Park Ji-Yong
    • Journal of information and communication convergence engineering
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    • v.2 no.3
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    • pp.153-156
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    • 2004
  • A planar active retrodirective four-element array with subharmonic phase conjugation mixers based on anti-parallel diode pairs (APDPs) is proposed. As compared to previous phase conjugation mixers using twice RF frequency for LO frequency, the proposed conjugation mixers need only half RF frequency so that it can be easily applied for millimeter-wave applications. Receiving, transmitting, local oscillator, and intermediate frequencies are 5.79, 5.81, 2.9 GHz, and 10 MHz. Monostatic RCS and Bistatic RCS measurements at source locations of $0^{\circ},\;-20^{\circ},\;and\;28^{\circ}$ show good agreement with the calculated data.