• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.22-26
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• 2013

The author analyzes the luminous efficiency of the phosphor-conversion white light-emitting diode (LED) that consists of a blue LED chip and a yellow phosphor. A theoretical model is derived to find the relation between luminous efficiency (LE) of a white LED, wall-plug efficiency (WPE) of a blue LED chip, and the phosphor absorption ratio of blue light. The presented model enables to obtain the theoretical limit of LE and the lower bound of WPE. When the efficiency model is applied to the measured results of a phosphor-conversion white LED, the limit theoretical value of LE is obtained to be 261 lm/W. In addition, for LE of 88 lm/W at 350 mA, the lower bound of WPE in the blue LED chip is found to be ~34%. The phosphor absorption ratio of blue light was found to have an important role in optimizing the luminous efficiency and colorimetric properties of phosphor-conversion white LEDs.

• 한국버섯학회지
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• 제15권4호
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• pp.259-263
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• 2017

표고 '농진고'를 LED 혼합광에 따른 갓의 색차 및 경도차를 확인한 결과 갓의 명도값은 형광등 처리구 대비 LED혼합광 처리구 모두 낮아지는 결과를 나타내었다. 적색도는 형광등 처리구에 비해 처리구 모두 높아졌고, 황색도는 낮아지는 결과를 보였다. 광원별 자실체의 생육특성을 조사한 결과 형광등 대조구 대비 처리구 모두에서 갓직경이 컸으며, 자실체들에 대한 균일도는 형광등 처리구 대비 LED를 사용하였을 경우 낮은 값을 나타내어 형광등을 처리하는 것보다 균일도가 있는 것으로 나타났다. 대직경은 처리구간 큰 차이를 보이지는 않았으나 White Green LED에서 다른 처리구보다 높은 것으로 조사되었고, 대길이는 형광등 처리구보다 LED처리구 모두에서 다소 높게 조사되었다. 갓직경과 대길이의 비를 조사한 결과 White Green LED을 제외한 White LED와 White Blue LED에서 형광등 처리구 대비 높은 값을 나타내어 대길이에 비해 갓의 직경이 길어지는 것을 확인할 수 있었다. 자실체 물추출물의 항산화능을 확인한 결과 형광등 처리구에서 가장 높은 항산화능을 확인할 수 있었고 LED 처리는 White LED처리에서 가장 큰 항산화능을 확인하였고 White Green LED, White Blue LED간에는 유의한 차이를 보이지 않았으나 LED처리는 Vitamin C 보다 높은 항산화능을 나타내었다. 위의 결과를 통해 White LED와 White Blue 처리가 표고버섯 자실체의 생육 및 항산화능에 영향을 미치는 광원임을 확인할 수 있었다.

• 원예과학기술지
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• 제35권1호
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• pp.21-29
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• 2017

This study was conducted to determine the effects of artificial lighting sources on vegetative growth of Phalaenopsis and Doritaenopsis (an intergeneric hybrid of Doritis and Phalaenopsis) orchids. One - month - old plants were cultivated under fluorescent lamps, cool - white light - emitting diodes (LEDs), or warm - white LEDs at 80 and $160{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. The blue (400 - 500 nm) : green (500 - 600 nm) : red (600 - 700 nm) : far - red (700 - 800 nm) ratios of the fluorescent lamps, cool-white LEDs, and warm-white LEDs were 1 : 1.3 : 0.8 : 0.1, 1 : 1.3 : 0.6 : 0.1, and 1 : 2.7 : 2.3 : 0.4, respectively. Each light treatment was maintained for 16 weeks in a closed plant-production system maintained at $28^{\circ}C$ with a 12 h photoperiod. The longest leaf span, as well as the leaf length and width of the uppermost mature leaf, were observed in plants treated with warm-white LEDs. Plants grown under fluorescent lamps had longer and wider leaves with a greater leaf span than plants grown under cool-white LEDs, while the maximum quantum efficiency of photosystem II was higher under cool-white LEDs. The vegetative responses affected by different lighting sources were similar at both 80 and $160{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Leaf span and root biomass were increased by the higher light intensity in both cultivars, while the relative chlorophyll content was decreased. These results indicate that relatively high intensity light can promote vegetative growth of young Phalaenopsis plants, and that warm - white LEDs, which contain a high red-light ratio, are a better lighting source for the growth of these plants than the cool-white LEDs or fluorescent lamps. These results could therefore be useful in the selection of artificial lighting to maximize vegetative growth of Phalaenopsis plants in a closed plant - production system.

• 한국미생물·생명공학회지
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• 제22권2호
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• pp.115-119
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• 1994

White mutant of Ganoderma lucidum(G4142) induced the non-basediocarpous basidiospores(NBB) from the aerial mycelia on agar media by the light illumination. Light was found to be necessary for NBB formation, but it also inhibited the growth of mycelium. The best sporulation was obtained at the periodic exposure of 16 hour light and 8 hour dark. Blue and yellow light were the most effective on sporulation, however, near UV and red light did not induce any spores. Effective light intensity for NBB bearing was about 1,000 lux as white light. Even after 16 days of culture, this strain did not form the pinhead nor chlamydospore. Optimum temperature for the mycelial growth and NBB formation were 30$\circ $C. Ganoderma lucidum G4142 exhibited the formation of stroma after five days of incubation at 30$\circ $C.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.276-279
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• 2003

The phase change upon reflection from target surfaces in white-light interferometer induces measurement errors when target surfaces are composed of dissimilar materials. We prove that this phase change on reflection considered of the polarization of the white-light causes the shift of both envelope peak position and fringe peak position of several tens of nanometer. In addition, we propose a new equation of white-light interference fringe pertinent to the polarization of source.

• Journal of the Optical Society of Korea
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• 제4권2호
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• pp.89-93
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• 2000

Recently a new signal processing algorithm for white light interferometry was presented. In this paper, the proposed signal processing algorithm was applied for absolute temperature measurement using white light interferometry. Stability testing and absolute temperature measurement were demonstrated. Stability test demonstrated the feasibility of absolute temperature measurement with an accuracy of 0.015 fringe. The test also showed that the absolute temperature measurement system using white light interferometry is capable of obtaining the theoretical minimum detectable change (0.0005 fringe), which is consistent with the performance predicted by the proposed signal processing algorithm.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.481-481
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• 2009

For a new generation of white light sources, we present the first example of a concentration-independent ultimate white-light-emitting molecule based on excited-state intramolecular proton transfer materials. Our molecule is composed of covalently linked blue- and orange-light-emitting moieties between which energy transfer is entirely frustrated, leading to the production of reproducible, stable white photo- and electroluminescence.

• 한국응용과학기술학회지
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• 제25권2호
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• pp.175-195
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• 2008

Recent years have brought remarkable developments in white light emitting devices (WLEDs) and white organic light-emitting devices (WOLEDs). However, their efficiency, CIE values, CRI and lifetime are still not ideal. This review covers detailed discussion about syntheses of organometallic complexes, inorganic phosphors and quantum dots used in WLEDs, WOLEDs and their electroluminescent properties until December 2007.

• 생물환경조절학회지
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• 제26권4호
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• pp.432-437
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• 2017

토마토 작물에 발생하는 B. tabaci에 대한 예찰을 위해 시설재배지뿐만 아니라 노지 재배에서도 노란색 점착카드트랩이 주로 사용되고 있다. 그러나, 예찰트랩의 색상과 굴절되는 빛의 강도 및 환경 변화에 따라 B. tabaci 유인력은 차이를 나타내고 있다. 따라서, 온실에 발생하는 B. tabaci 성충에 대한 light 트랩의 시설 재배지내의 이용 가능성을 평가하기 위해 white light (450-625nm) 및 yellow light (590nm) 트랩과 광원이 장착되지 않은 트랩을 이용하여 유인 활성을 비교하였다. 본 시험결과 광원별 B. tabaci 포획밀도는 yellow light 트랩(525 nm)에서 $168{\pm}7.6$(마리/트랩)로 가장 높은 유인활성을 나타내었으며, white light 트랩에서는 $106{\pm}4.6$(마리/트랩)으로 다소 낮은 개체수가 포획되었다. 그러나 대조구로 사용된 광원이 설치되지 않은 트랩의 경우 광원이 설치된 트랩보다 적은 $60{\pm}4.8$(마리/트랩)의 개체수가 포획되었다. 따라서, yellow light trap과 white light 트랩에서 높은 B. tabaci 성충의 유인력을 나타내었다. 이러한 결과를 바탕으로 yellow light 및 white light 트랩이 토마토 시설 재배지에서의 B. tabaci 성충에 대한 친환경적 해충 방제법의 일환으로 적용 될 수 있을 것으로 판단되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.648-650
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• 2007

We demonstrate highly efficient White Polymer Electrophosphorescent Light-emitting Diode using newly developed green and red light emitting heteroleptic iridium complex, Ir-(pq)2tpy, and blue light emitting fluorescent dopant, BczVBi. The best luminous efficiency reached 28cd/A with maximum luminance of 87000cd/m2. The scheme for determining optimum device architecture and dopant concentrations were constructed.