• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.827-832
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• 2008

A new diarylethene compound with donor and acceptor substituent was synthesized from 2,3-bis(2-methylbenzo[b]thiophene-3-yl)hexafluorocyclopentene (BTF) over 5 steps. The donor-acceptor structured BTF compound (TBTFE) showed spectral change to a longer wavelength through photochromism with a high cyclization quantum yield (0.56). The 3,4-ethylenedioxythiophene (T) and carboethoxy (E) groups directly connected to BTF unit promoted electrical change accompanied with the photoisomerization of the BTF unit. Photo-induced electrical switching was achieved from a photocell containing TBTFE doped polymer film, which showed reversible and stable current change over repeated cycles by the alternative UV/Vis irradiation, as estimated by the I-V plot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1733-1735
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• 2002

The important parameters deciding the fluctuation of laser beam are smoothing capacitor, frequency and the characteristics of laser resonator. In this thesis, we control the fluctuation of $CO_2$ laser in realtime by changing Duty-Ratio of IGBT and switching frequency with fixed the smoothing capacitor to improve the fluctuation of laser beam. We detect the light on laser resonator using a CdS photo sensor to improve ripple factor of laser beam and feedback fluctuated signals refined by a band pass filter into the control circuit to stabilize fluctuation actively. There is much to be desired in the realtime controlling technique of the light on laser discharge tube in electrical signal. We propose switching control technique with microprocessor and photo sensing technique by controlling switch devices optimum operation and feedback signals detected by a photo sensor into the laser power supply in order to improve ripple factor of the $CO_2$ laser beam.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1028-1032
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also, the former method shows higher transmittance than that of the latter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.118-122
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also. the former method shows higher transmittance than that of the latter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.278-279
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• 2006

In this study, we investigated the electro-optical (EO) characteristic of fringe-field switching (FFS) mode cell by the two kinds of ultraviolet (UV) alignment method on the organic thin film (polyimide Pl). The suitable organic layers for FFS cell and the aligning capabilities of nematic liquid crystal (NLC) using the in-situ photo-alignment method were studied. An unstable V-T curve of UV-aligned FFS-LCD with conventional photo-alignment method can be achieved. However, a stable V-T curve of UV-aligned FFS-LCD with in-situ photo-alignment method (1h), and V-T curve of UV-aligned FFS-LCD with in-situ photo-alignment method was much stable comparing with that of other UV-aligned FFS-LCD's, As a result, more stable EO performance of UV-aligned FFS-LCD with in-Situ photo-alignment method is obtained than that of the other UV-aligned FFS-LCD's.

• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.182-186
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• 2012

Resistance-change Random Access Memory(ReRAM) memory, which utilizes electrochemical control of metal in thin films of solid electrolyte, shows great promise as a future solid state memory. The technology utilizes the electrochemical formation and removal of metallic pathways in thin films of solid electrolyte. Key attributes are low voltage and current operation, excellent scalability, and a simple fabrication sequence. In this work, we investigated the nature of thin films formed by photo doping of $Ag^+$ ions into chalcogenide materials for use in solid electrolyte of Resistance-change RAM devices and switching characteristics according to field-effect.

• 조명전기설비학회논문지
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• 제28권1호
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• pp.36-44
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• 2014

The conventional central photo voltaic inverters have several problems. First, shadow problem in each solar panel, and high DC voltage problem from each panel because of concentration to one central inverter. Therefore, module integrated inverter is proposed to solve these problems. The inverter should be small and cost effective. The cost and size in the inverter depend on the inductor. So the switching frequency should be increased to reduce the inductor and total size, but there is a problem in efficiency because of the losses in turn-on and turn-off. In the paper, the critical conduction mode(CRM) switching method is adopted to reduce the switching loss and interleaving method is proposed to increase the efficiency in Flyback converter. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype system rated at 200W.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.1015-1016
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• 2006

The important parameters deciding the fluctuation of Accumulation style surgical operation of ventriculus laser beam are smoothing capacitor, frequency and he characteristics of laser resonator. In this thesis, we control the fluctuation of medical $CO_2C$ laser in realtime by changing Duty-Ratio of IGBT and switching frequency with fixed the smoothing capacitor to improve the fluctuation of laser beam. We detect the light on laser resonator using a CdS photo sensor to improve ripple factor of laser beam and feedback fluctuated signals refined by a band pass filter into the control circuit to stabilize fluctuation actively. There is much to be desired in the realtime controlling technique of the light on Accumulation style surgical operation of ventriculus laser discharge tube in electrical signal. We propose switching control technique with microprocessor and photo sensing technique by controlling switch devices optimum operation and feedback signals detected by a photo sensor into the laser power supply in order to improve ripple factor of the $CO_2$ laser beam.

• 전기전자학회논문지
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• 제24권2호
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• pp.392-402
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• 2020

본 논문은 광센서 없는 태양광 추적 시스템을 제안한다. 태양광 추적, MPPT, ESS, 모니터링의 4가지 기능을 모듈화하여 시스템을 구현하였다. 9개의 태양광 패널을 기본단위로, 바람의 영향을 저감하고, 광센서 없이 태양광 추적이 가능하도록 상하좌우 패널의 높낮이를 다르게 한 격자형 구조를 채택하였다. 저가형 MCU를 이용한 부스트 컨버터 PWM 스위칭을 위해 기존 MPPT의 연산 방법을 개선하였다. ESS 모듈은 리튬 이온 배터리 12개(직렬 3셀과 병렬 4셀)를 기본 단위로 구성하여 온도 및 전기 특성의 이상 유무 감시가 가능하게 하였다. 각 모듈의 MCU는 Atmega128 또는 Raspberry PI로 구성하였으며 운전 정보를 상호 교환하고, IoT 기술을 응용하여 실시간 원격 모니터링과 클라우드에 데이터베이스를 구축하여 유지보수가 가능하게 하였다. 실험을 위해 제작된 태양광 발전 시스템의 운전 데이터는 각 모듈의 분산 및 원격 모니터링의 가능성, 유지보수의 편의성 및 광추적 성능을 증명한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.65-68
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• 1998

The mechanism of response time and viewing angle in in-plane switching ( IPS ) liquid crystal display ( LCD ) were investigated. The response time of photo-aligned IPS-LCD is fast compared with rubbing-aligned IPS-LCD on polyimide ( PI ) surface. The decay time $\tau$$\_$d/ is decreased with increasing the azimuthal anchoring energy A $\psi$ due to the steric interaction between the LC molecules and side chain of polymer. The viewing angle of IPS-LCD is increased by using photo-depolymerizatin method ; about ${\pm}$70$^{\circ}$at all direction.