• ETRI Journal
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• 제43권5호
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• pp.891-899
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• 2021

We propose a stray inductance extraction method on power modules of the few-kilovolts/several-hundred-amperes class using only low voltages and low currents. The method incorporates a double-pulse generator, a level shifter, a switching device, and a load inductor. The conventional approach generally requires a high voltage of more than half the power module's rated voltage and a high current of around half the rated current. In contrast, the proposed method requires a low voltage and low current environment regardless of the power module's rated voltage because the module is measured in a turn-off state. Both theoretical and experimental results are provided. A physical circuit board was fabricated, and the method was applied to three commercial power modules with EconoDUAL3 cases. The obtained stray inductance values differed from the manufacturer-provided values by less than 1.65 nH, thus demonstrating the method's accuracy. The greatest advantage of the proposed approach is that high voltages or high currents are not required.

• 전기전자학회논문지
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• 제27권4호
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• pp.630-635
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• 2023

SiC는 고온, 고전압을 비롯한 악조건에서의 내성이 기존 산업분야의 대다수를 점유하고 있는 Silicon에 비해 우수하여 전력반도체 분야에서 Silicon의 위치를 대체하여 가고 있다. 본 논문은 전력 반도체 소자 중 하나인 4H-SiC Planar MOSFET에 알루미늄으로 Gate를 형성하여 다결정 Si 게이트와 대비, 파라미터 값들이 일관성을 갖도록 하였으며, SiC MOSFET의 채널 도핑 농도에 변화를 주어 문턱전압과 항복전압, IV 특성을 연구하였다.

• 반도체디스플레이기술학회지
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• 제8권2호
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• pp.59-62
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• 2009

In order to check the validation of LC simulation, 0.7 inch LCOS panel in full-HD resolution was fabricated and used for the electro-optical measurement. Compared the measured data with the calculated data, the averaged difference was 1.72% under 0 ~ +6 V bias on pixel electrode. To improve the optical characteristics of full-HD LCOS panel, the planar structure and trench structures (0.1 um, 0.2 um and 0.3 um-in-depth) between adjacent pixels were investigated with LC simulation. The planar structure showed the higher reflectance and faster reflectance-voltage response time than the trench structure. The optical fill factor and contrast ratio of planar structure were also higher than those of trench structures. As compared 1 um-in-depth trench structure resembled to the real structure with the planar structure, the optical fill factor was improved by 1.15% and the contrast ratio was improved by 5.26%. In order to minimize the loss of luminance and contrast ratio, the planar structure need to be applied between adjacent pixels.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1473-1475
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• 2006

The electro-optic properties of an active-matrix polymer network liquid crystal display (AM-PNLCD) with crossed polarizer films to improve its contrast ratio were evaluated. By using crossed polarizer films, it shows good contrast ratio as well as wide viewing angle and adequate response time at normal TFT-twisted nematic (TN) LCD driving voltage (2.8V).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.32-32
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• 2010

본 논문에서는 대전입자층과 충전비율에 따른 구동특성을 평가하였다. 소자 제작은 동일한 cell gap에 대전입자의 입자층과 충전비율을 다르게 하여 패널에 주입하였으며 문턱전압 및 구동전압에서의 구간에서 실제로 움직이는 대전입자의 구동입자 개수와 면적을 측정하였다. 그 결과 대전입자층 및 충전비율에 따라서 구동전압 및 구동입자수와 white, black의 차지하는 면적비율의 차이가 있었으며, 면적측정으로 contrast ratio를 평가하고 실제로 구동하는 입자의 비율을 확인하였다.

• 한국광학회지
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• 제10권3호
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• pp.259-264
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• 1999

CRT 디스플레이 시스템의 입력 신호와 방출되는 빛의 세기 관계를 유도하였다. 빛의 세기는 입력 신호뿐만 아니라 비디오 보드, 전자회로부, 그리고 CRT 특성에도 의존한다. 특히 전자회로부의 증폭률과 옵셋 전압에 따라 휘도 곡선이 크게 달라진다. 본 연구에서는 디스플레이의 contrast 누름 단추와 brightness 누름 단추를 사용하여 전자총의 독립성이 최대로 유지되는 최적상태로 시스템을 설정하였다. 최적상태에서의 디스플레이 시스템의 시간 안정성과 화면 균일도, 그리고 색 선명도를 평가하고, 실제 사용환경을 고려하여 암실과 명실에서의 명암대비를 비교하였다.

• 공업화학
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• 제30권2호
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• pp.205-211
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• 2019

지난 수십 년 동안 고분자 분산형 액정(polymer dispersed liquid crystal, PDLC)은 전기광학적으로 전환이 가능한 특성으로 인해 빛의 투과도를 자유롭게 조절할 수 있는 smart window를 개발하는 물질로서 주목을 받아왔다. 본 연구에서는 높은 구동전압과 낮은 명암비 등의 PDLC 문제점을 해결하기 위해 아크릴계 단량체 2-hydroxyethyl acrylate (2-HEA)와 ethylene glycol phenyl ether acrylate (EGPA)의 조성이 PDLC의 전기광학 특성에 미치는 영향을 평가하였다. 상온에서 10 cps 이하의 낮은 점도를 나타내는 2-HEA와 EGPA 단량체를 사용하여 제조하는 경우 보다 쉽게 capillary action에 의해서 indium tin oxide (ITO) glass 사이에 주입하는 공정이 가능하였다. Phenyl group를 포함한 EGPA 단량체가 대부분으로 이루어진 1 : 9인 단량체 혼합물로 만들어진 PDLC cell의 경우 전기장을 인가하지 않은 경우에도 불투명한 상태가 관측되지 않았고 인가 전압에 따라 매우 불안정한 투과율을 나타내었다. Cell gap thickness가 증가함에 따라 문턱전압(threshold voltage, $V_{th}$)과 포화전압(saturation voltage, $V_{sat}$)도 증가하는 경향을 나타내었으며, $20{\mu}m$의 cell gap thickness를 갖는 PDLC cell이 10과 $40{\mu}m$의 경우 보다 상대적으로 높은 명암비를 나타내었다. 특히, 7 : 3 비율의 2-HEA : EGPA 단량체 혼합물을 사용하여 제조된 PDLC cell의 경우가 낮은 구동전압과 높은 명암비의 가장 우수한 전기광학적 특성을 나타내었다.

• 조명전기설비학회논문지
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• 제29권4호
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• pp.11-17
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• 2015

While most switching devices are based on PN junctions, a single layer can realize a switching device in the case of vanadium dioxide($VO_2$) thin films. In this paper, bidirectional current triggering(switching) is demonstrated in a two-terminal planar device based on a $VO_2$ thin film by illuminating the film with an infrared laser at 1550nm. To begin with, a two-terminal planar device, which had a $30{\mu}m$-wide $VO_2$ conducting layer and an electrode separation of $10{\mu}m$, was fabricated. A specific bias voltage range for stable bidirectional laser triggering was experimentally obtained by measuring the current-voltage characteristics of the fabricated device in a current-controlled mode. Then, by constructing a test circuit composed of the device, a standard resistor, and a DC voltage source, connected in series, the transient response of laser-triggered current and its response time were investigated with a DC bias voltage, included in the above specific bias voltage range, applied to the device. In the test circuit with a DC voltage source of 3.35V and a $10{\Omega}$ resistor, bidirectional laser triggering could be realized with a maximum on-state current of 15mA and a switching contrast of ~78.95.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.297-300
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• 2007

In this study, we have attempted a new method to enhance the coloring of dye on the $TiO_2$ surface in the dye sensitized solar cell. In the conventional coloring process in a dye sensitized solar cells, dye is absorbed by the covalent bond between TiO2 and dye molecule while the photo-electrode coated with $TiO_2$ layer is soaked in dye solution for about 12-24 hours. But this process takes long time, so we have researched more effective and faster way than the conventional process by applying electric field. Three kinds of electric power such as direct voltage, alternating voltage and pulse voltage were applied to the transparent conducting oxide during the coloring process. As a result, we achieved improved power, fill factor and efficiency of dye-sensitized solar cell in case of applying direct voltage and pulse voltage. In contrast, alternating voltage tend to reduce the dye adsorption on the $TiO_2$ surface and hence the efficiency. We measured the absorption spectra of dye by UV-VIS spectrophotometer before and after soaking the $TiO_2$ in the dye and found no characteristic change in the dye was observed. In this study, we researched on shortening time of coloring process which spent much time in the whole process.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.205-211
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• 2010

In this study, a Magnetic stimulation Pulse Train control technique is introduced and applied to Flyback converter operating in discontinuous conduction mode. In contrast to the conventional pulse width modulation control scheme, the principal idea of a Magnetic stimulation Pulse Train is to achieve output voltage regulation using high and low power pulses. The proposed technique is applicable to any converter operating in discontinuous conduction. However, this work mainly focuses on Flyback topology. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.