• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.285-286
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• 2007

Current distributions according to electrode patterns in vertical structured InGaN/GaN LED (light emitting diode) were investigated quantitatively by utilizing three dimensional electrical circuit modeling method. The uniformity of the injected current density in the active layer was compared among different electrode patterns. It was found that the current uniformity was greatly dependent on the electrode pattern in vertical InGaN/GaN LEDs.

• Journal of Applied Biological Chemistry
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• 제58권2호
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• pp.101-104
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• 2015

긴털가루응애 성충을 청색(470 nm), 녹색(520 nm), 황색(590 nm)과 적색(625 nm) light-emitting diode (LED)에서 파장별 광량을 20, 40 및 60 lx로 달리하여 주광성 행동반응 판별장치(LED-equipped Y-maze chamber)에서 상업적 양성대조구 BLB와 유인활성을 비교하였다. 긴털가루응애는 사용된 청색, 녹색, 황색 및 적색 LED 파장과 20, 40 및 60 lx 광량에서 특별한 행동반응특성을 발견하지 못하였으며, 양성대조구로 이용된 BLB에서도 긴털가루응애는 음성/양성주광성 반응을 보이지 않았다. 이러한 결과를 근거로 긴털가루응애는 LED 주광성 행동반응 판별장치에서는 친환경적 해충방제 가능성을 제시하지 못했다.

• 전력전자학회논문지
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• 제19권6호
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• pp.564-571
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• 2014

A single-stage current-balancing multi-channel light-emitting diode (LED) driver is proposed in this study. The conventional LED driver system consists of two cascaded power conversion stages, i.e., an isolation DC/DC converter and LED driver. LED driver is usually implemented with the same number of expensive boost converters as those of LED channels to tightly control the current through each LED channel. Therefore, its overall system size is not only bulky, but the cost is rather high. By contrast, the proposed LED driver system is composed of a single power stage with the DC/DC converter and LED driver merged. Although the current balancing circuit of the proposed LED driver requires only passive devices instead of expensive boost converters, all currents through multi-channel LEDs can be well balanced. Therefore, the proposed LED driver features a small system size, improved efficiency, and low cost. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for a 46" LED TV.

• Journal of information and communication convergence engineering
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• 제19권4호
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• pp.269-275
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• 2021

Light-emitting diodes (LEDs) are modulated using a square wave pulse sequence for flicker prevention and dimming control in visible light communication (VLC). In a VLC transmitter, the high and low bits of the non-return-to-zero (NRZ) data are converted to two square waves of different frequencies, which continue for a finite time defined by the fill ratio in an NRZ bit time. As the average optical power was kept constant and independent of data transmission, the LED was flicker-free. Dimming control is carried out by changing the fill ratio of the square wave in the NRZ bit time. In the experiments, the illumination of the LED light was controlled in the range of approximately 19.2% to 96.2% of the continuous square wave modulated LED light. In the VLC receiver, a high-pass filter combined with a latch circuit was used to recover the transmitted signal while preventing noise interference from adjacent lighting lamps.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.2-6
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• 2009

This presentation reviews the current progress in the technology of Light Emitting Diode (LED) as it relates to the LED backlight for Liquid Crystal Display (LCD). A vivid description is given about the performance of LED that is still on the rise and certain limitations of LED that is on the decline.

• 한국수산과학회지
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• 제51권1호
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• pp.64-71
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• 2018

This study was conducted to investigate the effects of light intensity and wavelength on the growth of Tetraselmis suecica and Tetraselmis tetrathele. These species were exposed to a blue light-emitting diode (LED; max=450 nm), a yellow LED (max=590 nm), a red LED (max=630 nm) and a fluorescent lamp (three wavelengths). The maximum growth rates (${\mu}_{max}$) of T. suecica and T. tetrathele under a red LED were 1.12/day and 0.95/day, respectively. Under a yellow LED, growth rates were 70% of the values for red wavelength, with low half-saturation constants (Ks). The optimum light source to ensure economically effective and productive growth in a Tetraselmis culture system (Photo-Bioreactor) would thus appear to be a three-phase culture, wherein a yellow LED is used during the lag phase and initial exponential phase to increase growth rate, followed by a red LED during the middle exponential phase to maximize growth rate, and finally a yellow LED again during the late exponential phase and stationary phase to achieve increased yield of useful bioactive substances.

• 한국광학회지
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• 제23권2호
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• pp.55-63
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• 2012

본 논문에서는 광생물 반응기의 조명 시스템으로 활용될 LED(Light-Emitting Diode)용 도광판의 광학설계 및 제작 결과에 대해 보고한다. 도광판 설계를 위해 광원, 반사필름, 도광판 패턴에 대한 모델링을 수행하였다. 특히, 도광판 패턴의 경우 램버시안 산란체(Lambertian Scatterer)로 모델링을 수행하였는데, 테스트용으로 제작된 도광판의 조도분포와 부합하는 모델 파라미터(반사율, 산란체의 폭)를 매칭 시뮬레이션을 통하여 추출하였다. 추출된 모델 파라미터를 사용하여 광학설계를 수행하였으며, CNC(Computer Numerical Control) 가공을 통해 도광판을 제작하였고, 평균조도와 조도균일도 등의 광학 특성을 측정하였다.

• 한국식품과학회지
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• 제45권6호
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• pp.763-769
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• 2013

본 연구는 전자코를 이용하여 시판 콩기름의 휘발성분이 파장에 영향을 받는지 알아보고자 암실과 형광등 및 파장이 다른 LED 광원을 PE 용기에 조사하면서 12주 동안 변화되는 휘발성분의 패턴 변화를 분석하였다. 콩기름의 휘발성분의 변화는 저장기간동안 암실 처리구에서 가장 적고 천천히 일어났으며, 형광등 처리구에서 가장 크고 급격한 변화가 일어나는 것을 보여주었다. 저장 초기인 4주에는 형광등 처리구를 제외한 모든 처리구에서 미세한 변화가 일어났으며, 저장 12주에는 형광등 처리구 다음으로 파란색과 백색 LED 처리구에서 큰 변화를 보여준 반면 초록색 LED 처리구에서는 변화가 적었다. 파란색과 흰색 LED 처리구는 저장 12주째에서 급격한 휘발성분의 변화가 나타났다. 하지만 빨간색과 초록색 LED 조사 시에는 8주째에 급격한 휘발성분이 생성된 것에 비하여, 저장 12주째에는 휘발성분의 변화가 매우 감소하는 것을 보여주었다. 또한 초록색 LED 처리구에서 가장 적은 변화를 보였다. 이러한 결과를 토대로 볼 때 초록색 LED 광원에서 콩기름을 전시 판매하는 것이 바람직하며, 형광등과 파란색, 백색 LED 광원은 바람직하지 못한 것으로 판단된다. 또한, 전시 판매가 아니라면 암실에서 저장하는 것이 가장 바람직할 것으로 예상되는 바이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.289-289
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• 2009

Light emitting diode(LED) has many advantages including lower energy consumption and longer lifetime and eco-friendly in comparison with traditional light sources. Spheric plastic lens generally used in LED lighting occurs aberration and ghost image which give displeasure and deteriorate vision quality in human eyes. Using the optical program (LightTools$^{TM}$, CodeV$^{TM}$), we were confirm the aberration and ghost image in optical simulation and employed aspheric lens form in the lens design to improve these problems. From the comparison of the simulation results between the aspheric lens and the spheric lens, we were ascertain to be improved both aberration and Ghost image.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.126-129
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• 2001

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process was performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.