• Research in Plant Disease
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• v.22 no.2
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• pp.100-106
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• 2016

We have studied the mycelia growth of four soil-borne fungal pathogens under light qualities and two lighting types (continuous and intermittent) provided by light-emitting diodes (LEDs). As a result, each mycelia growth on Phytophthora cactorum KACC40166, Athelia rolfsii KACC40170, and Helicobasidium mompa KACC40836 strain showed the similar growth rates within 10% or less difference among treatments compared to dark control, regardless of lighting types. However, the mycelia growth on Rosellinia necatrix KACC40168 strain was significantly suppressed by blue, blue+green and blue+red LED as well as fluorescent lamp compared to a dark control, in common with lighting types. The melanin pigment on R. necatrix KACC40168 strain showed relatively to induce more strongly under green LED and fluorescent lamp, whereas no induction under red LED and a control, regardless of lighting types. Thus, the hypha width on R. necatrix KACC40168 was significantly thinned by blue and blue+green LED compared to a control, in common with lighting types.

• Electrical & Electronic Materials
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• v.17 no.5
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• pp.21-29
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• 2004

현재 LED에 대한 관심과 투자, 수요는 날이 갈수록 증가되고 있다. 이러한 가장 큰 이유는 현재의 광원보다 에너지 절감효과가 뛰어나고 수명이 우수하기 때문이다. 최근 질화물계 반도체를 기반으로 한 청색 및 백색 LED가 상용화되고 그 효율이 증대됨에 따라 그 응용시장이 크게 확대 되면서 본격적인 LED 응용 시대가 도래하고 있다. 현대와 같이 에너지 절감이 절실한 시기에 LED의 가장 큰 강점은 에너지 소비량이 기존 백열전구의 단 10분의 1에 불과하다는 점이다. 청색, 백색 LED의 제작초기에는 휘도나 효율 면에 있어서 백열전구나 형광등에 비해 많은 문제가 있었으나 현재의 기술은 이러한 문제점을 크게 보완시켜 상용화가 가능하게 하였다. 또한 본격적인 대량 생산 체제가 갖추어지면 백열 전구나 형광등에 비해 훨씬 높은 원가 절감 효과를 가져 올 것이 확실하며, 이러한 효과는 현재의 많은 기업체나 연구소의 관심도, 수요 현황으로 볼 때 2007년 경에는 확연히 나타날 것으로 판단된다.(중략)

• Journal of Mushroom
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• v.12 no.4
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• pp.258-262
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• 2014

We aim to elucidate suitable mixed color of light during development of fruit body in Pleurotus ostreatus. The four mixed color of LED(Light Emitting Diode), blue and white, green and white, blue and green and green and red LED, were irradiated for formation of fruit-body. First, as effect of mixed color of LED, the properties of fruit body of P. ostreatus in blue and white LED irradiation were showed higher commercial yields than those in control(fluorescent lamp). And the ergothioneine was the highest at the blue and white LED. Second, we could obtain higher commercial yields than those at the $1{\mu}mol/m^2/s$ of light intensity by blue and white LED in P. ostreatus.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.294-301
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• 2016

This study was conducted to analyze the seedling quality of korean melon and the growth after transplanting of korean melon nursed under the LED sources. LED sources were RB7 (Red:Blue=14:2), RB3 (Red:Blue=12:4) and Blue(B=16). Photosynthetic photon flux density(PPFD) was 50, 100 and $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. The lighting treatment was started after graft-taken and was applied for 20 days at 4 hours(05:30 and 07:30, 17:30 and 19:30) per day. Plant height and stem diameter of scion were longer and thicker under a high ratio of blue light condition. Dry matter ratio and compactness were highest in RB3 compared to the other LED sources treatments. $CO_2$ exchange rate increased $5.44{\mu}molCO_2{\cdot}m^{-2}{\cdot}s^{-1}$ under RB7 $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and dropped to negative values under control. PPFD $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of RB3 resulted in the longest plant height by 132.3cm and flowering ratio also was the highest by 75%.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.330-339
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• 2014

Growth and anthocyanins of lettuce (Lactuca sativa L., 'Mid-season') grown under LED lamps with blue light in the range of 430-470 nm or with red light in the range of 630-670 nm were analyzed in this study. Cool-white fluorescent light was used a s the control. P hotosynthetic photon flux, p hotoperiod, air temperature, relative humidity, and $CO_2$ concentration in a closed plant production system were $201{\pm}2\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 16/8 hours (day/night), $22/18^{\circ}C$, 70%, and $400{\mu}mol{\cdot}mol^{-1}$, respectively. At 21 days after light quality treatment, growth characteristics and anthocyanins content of lettuce as affected by the peak wavelength of blue or red LED were significantly different. Among peak wavelengths treated in this stusy, R1 treatment (peak wavelength 634 nm) and R6 treatment (peak wavelength 659 nm) were effective for increasing leaf width, leaf area, shoot fresh weight, and photosynthetic rate of lettuce. B5 treatment (peak wavelength 450 nm) and B4 treatment (peak wavelength 446 nm) increased the anthocyanins concentration and chlorophyll content in lettuce leaves, respectively. Anthocyanins in lettuce leaves increased linearly with decreasing hue value of leaf color and with increasing SPAD value of lettuce leaves. From these results, it was concluded that the red LED with peak wavelengths of 634 nm and 659 nm and the blue LED with peak wavelengths of 450 nm can be used as potential light spectra for increasing the yield and anthocyanins accumulation of leafy vegetable.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.164-170
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• 2012

The dependance of degradation on the blue-peak wavelength is investigated with the blue light-emitting diode (LED) of InGaN/GaN with respect to the optical and the electrical characteristics of the devices. The LED devices emitting the blue-peak wavelength ranging from 437 nm to 452 nm is prepared to be stressed for a long aging time with three different currents of 60 mA, 75 mA and 90 mA, respectively. The degradation of optical intensity is observed with and without phosphor in the devices. The device without phosphor has been degraded significantly as the wavelength of blue-peak is decreased while the optical intensity of LED device with phosphor become less sensitive than that of device without phosphor. The electrical property does not depend on the emission peak wavelength. However, the series-resistance of LED device is slowly increased as the aging time is increased. The deformation of device is observed severely the short wavelength of blue-peak even with the same current since the short wavelength is absorbed substantially at the materials of device during the aging time. Consequently, in order to enhance the lifetime of LED devices, it is important to understand the optical degradation property of the materials against the specific wavelengths emitted from the blue chip.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.164-164
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• 2012

청색 발광 다이오드의 광추출 효율 향상 및 전기적 특성 향상을 위하여 기판이 되는 사파이어에 마이크로급 패턴을 형성하는 공정이 일반적으로 사용되고 있다. 기존의 공정과는 달리, 저가의 간단한 공정을 통해 쉽게 유사한 성능 향상을 얻기 위하여, 나노임프린트 리소그래피 공정을 도입하여 사파이어 기판 상에 일정한 주기와 형태를 갖는 나노 패턴을 형성하였으며, 이를 이용하여 제작한 발광 다이오드의 성능이 전기적, 광학적 측면에서 크게 향상되었음을 확인할 수 있었다.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.2
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• pp.123-133
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• 2020

Four LEDs (blue, green, red, and white light) were tested to identify the most attractive wave length to utilize as the forecasting tools for the B. tabaci in glass houses. Attractiveness was evaluated by the total number of the B. tabaci attached to a yellow sticky trap. In the condition of no host plant supplement, the attraction efficacy was ordered from high to low as blue light (107.3±2.5), white light (83.0±12.1), red light (58±21.8), and green light (39.7±8.1). In the supplement of the host plant, the attraction was observed in the order of blue light (52±17.4), red light (38.7±5.8), green light (12.7±1.5), and white light (11.7±5.0). In both experimental conditions, blue light showed the highest attraction. In terms of the host plant effect to LED attraction, it varied following as white light (85.9%), green light (68.1%), blue light (51.6%), and red light (33.3%). This result suggests that red light is the least affected by the host plant. In the evaluation of the relative control efficacy, it was determined following as red light (66.7%), blue light (48.5%), green light (31.9%) and white light (14.1%) (F_3,8 = 14.7, P = 0.001). Taken together, blue light had a very high initial attraction, and red light was revealed low attraction effect by the supplement of the host plant. In field demonstration experiments, a high attractive efficacy was not observed due to low-temperature conditions, but similar higher attractive efficacy was observed in blue and red lights compared to the control. The commercialization of LEDs using red and blue in the future is expected to provide important information regarding B. tabaci population density forecast in glass house.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.214-219
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• 2013

This study was conducted to examine the effect of LED light quality and treatment time on the growth and flowering in potted plants of Impatiens (Impatiens hawkerihybrid). Plant height of Impatiens was enhanced under Blue light, regardless of treatment time. Root length and stem diameter of Impatiens were enhanced by Red light or Blue light. The number of internodes was not influenced by LED light quality. The number of branches of Impatiens was increased under Blue light, but treatment time did not result in statistically significant differences. Leaf area was increased by all LED lights in Impatiens. The number of flower buds and open flowers was decreased by LED light, but days to flowering were reduced by Red light in Impatiens. Chlorophyll and anthocyanin content were not significantly affected by LED light, but anthocyanin content tended to increase by Blue light for 4 h after sunset. Fresh and dry weights were enhanced by Blue light in Impatiens.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.93-101
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• 2007

In order for bioremediate the benthic layer in polluted inner Bay, the effects of irradiance and wave-length irradiated from light emission diode (LED) on the growth of benthic diatom Nitzschia sp. (Hakozaki Bay strain of Japan) were investigated. The Nitzschia sp. was cultured under blue LED (450 nm), yellow LED (590 nm), red LED (650 nm) and fluorescent lamp (mixed wavelengths). At $25^{\circ}C$ and 30 psu, the growth of Nitzschia sp. showed its peak at $20\;{\mu}mol\;m^{-2}\;s^{-1}$ (blue LED) and $40\;{\mu}mol\;m^{-2}\;s^{-1}$ (fluorescent lamp), and was inhibited at the irradiance higher than that irradiance. Nitzschia sp. in yellow LED and red LED is fitted by a rectangular hyperbolic curve because no photoinhibition was observed under maximum irradiance used in this study. The irradiance-growth curves were described as ${\mu}=-0.46{\exp}(1-I/6.32)+0.46-0.00043I,\;(r^2=0.98)$ under blue LED, ${\mu}=0.42(I+7.87)/(I+58.9),\;(r^2=0.99)$ under yellow LED, ${\mu}=0.39(I+3.39)/(I+21.6),\;(r^2=0.94)$ under red LED, ${\mu}=-0.38{\exp}(1-I/7.23)+0.38-0.00016I,\;(r^2=0.96)$ under fluorescent lamp. Maximum specific growth rate of blue LED, yellow LED, red LED and fluorescent lamp was $0.44\;day^{-1},\;0.42\;day^{-1},\;0.39\;day^{-1}$ and $0.37\;day^{-1}$, respectively. The absorption coefficient ($a_{ph}$) of Nitzschia sp. was similar under all the wavelengths (400 nm-700 nm), although maximum $a_{ph}$ was $0.0224\;m^2\;mg\;chi.\;{\alpha}^{-1}$ in 472 nm and $0.0179\;m^2\;mg\;chi.\;{\alpha}^{-1}$) in 663 nm. The results may indicate the possibility of environmental improvement around the benthic layer in polluted coastal area because microphytobenthos growth is stimulated by means of irradiated blue LED at the benthic boundary layer during both autumn and winter, and yellow LED, which might have been suppressed growth of harmful algae, at the layer during both spring and summer.