• ETRI Journal
• /
• 제33권6호
• /
• pp.880-886
• /
• 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.

• Current Photovoltaic Research
• /
• 제3권4호
• /
• pp.107-111
• /
• 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 Journal of Advanced Prosthodontics
• /
• 제5권4호
• /
• pp.457-463
• /
• 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.

• 한국전자파학회논문지
• /
• 제23권2호
• /
• pp.220-228
• /
• 2012

본 논문에서는 밀리미터파 탐색기의 수신기 보호용으로 사용할 낮은 누설 전력을 가지는 Ka 대역 능동 리미터 설계 및 제작 기법을 설명하였다. 낮은 누설 전력을 구현하기 위해서 송신 펄스 주기 신호와 입력 전력의 크기에 따라 리미터를 제어할 수 있는 능동 리미터 제어 회로를 제안하였다. 능동 리미터는 전형적인 2단 수동 리미터에 방향성 결합기, 검파기, 연산 증폭기 및 과전류 보호용 저항으로 구성된 궤환 회로로 구성되어진다. 제작된 Ka 대역 능동 리미터 측정 결과, 주파수 대역은 1 GHz, 약 신호 시 삽입 손실은 3.5 dB 이하, 능동 제어시 최대 감쇄량 46 dB, 4 W RF 입력 시 정상 누설 전력은 -7.5 dBm을 보였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.77-81
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.377-377
• /
• 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.

• 대한전자공학회논문지
• /
• 제9권4호
• /
• pp.1-6
• /
• 1972

본초광대역AMqus조기는 회로구성요소에 초광대역 AM변조작용을 제한하는 동조회로를 사용하지 않고 전송선의 임피단스변환성을 이용하여, 인가한 변조신호의 진폭에 비례되게 반송파의 진폭이 변하도록 하는 변조원리를 이용한 것이다. 본논문에서는 이 AM변조기를 해석연구 하였으며 또 본변조기의 Active 소자로서 VHF 진실관, FET, VVC 다이오우드를 각각 사용하여 실험하여 얻은 AM변조파형의 사진도 첨가하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1994년도 하계학술대회 논문집 A
• /
• pp.553-555
• /
• 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.

• 대한전자공학회논문지
• /
• 제25권1호
• /
• pp.94-100
• /
• 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.

• Journal of information and communication convergence engineering
• /
• 제2권3호
• /
• pp.153-156
• /
• 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.