• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.9-14
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• 2014

We numerically investigate the effect of sunlight polarization on the absorption efficiency of V-shaped organic solar cells (VOSCs) using the finite element method (FEM). The spectral distribution of absorbance and the spatial distribution of power dissipation are calculated as a function of the folding angle for s-and p-polarized light. The absorption enhancement caused by the light-trapping effect was more pronounced for s-polarized light at folding angles smaller than $20^{\circ}$, where s-polarized light has a relatively larger reflectance than p-polarized light. On the other hand, the absorption efficiency for p-polarized light is relatively larger for folding angles larger than $20^{\circ}$, where the smaller reflectance at the interface of the VOSC is more important in obtaining high absorption efficiency.

• 원예과학기술지
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• 제34권1호
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• pp.84-93
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• 2016

인공광 식물공장은 조명에 많은 전력이 소요되므로 광이용효율의 향상은 필수적이다. 본 연구에서는 식물공장의 LED 광원에 산란 유리를 사용함으로써 광이용효율을 향상하고자 하였다. 실험에는 Haze factor 40%와 80%의 산란 유리가 적용된 두 가지 처리구와 산란 유리를 사용하지 않은 대조구를 두었다. 3-D 광선추적기법을 이용하여 상추 작물의 군락 광분포를 분석하였으며 군락 광합성률은 밀폐 아크릴 챔버를 이용하여 측정하였다. 각 처리구 별로 16주의 상추를 수경재배 방식으로 28일간 재배하여 생장량을 비교하였다. 시뮬레이션 결과, 모든 처리구에서 작물의 상단부에 광량이 집중되었고 대조구에서 작물 상부에 광량 핫스팟이 발생하며 처리구에 비하여 광이용효율이 감소하였다. 총 광 흡수량은 대조구에서 가장 높았으나 유효 광 흡수량은 처리구에서 더 높았고 산란광의 비율이 높은 처리에서 더 높게 나타났다. 작물의 군락 광합성률과 생장량은 산란 유리를 사용한 처리구에서 대조구에 비해 높게 나타났다. 결과적으로 산란 유리의 이용을 통해 상추의 군락 내 광분포가 개선되었고 군락 광합성률 및 생장량이 증가하여 식물공장의 광이용효율이 향상되는 것으로 나타났다.

• 대한전자공학회논문지
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• 제25권6호
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• pp.647-653
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• 1988

A rapid thermal annealing system using tungsten halogen lamp has been designed and assembled. A control scheme where the temperature control is executed with calculated wafer temperature by considering the thermocouple delay rather than measured thermocouple temperature,is proposed. This control scheme gives more accurate control of the wafer temperature. In addition, the distribution of transmitted light power to the wafer in the system has been simulated, and lamp interval modification has been able to give more uniform light power distribution. Considering incident light spectrum, absorption, reflection, radiation of silicon, etc., temperature profile has been simulated. When the light power uniformity on the 3" wafer is below 1%, the temperature uniformity is about 2%.

• 한국멀티미디어학회논문지
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• 제24권11호
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• pp.1461-1471
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• 2021

This paper presents a light exposure correction algorithm for less pleasant images, acquired with a light metering failure. Since conventional tone mapping and gamma correction methods adopt a function mapping with the same range of input and output, the results are pleasurable for almost symmetric distributions to their intensity average. However, their corrections gave insufficient outputs for asymmetric cases at either bright or dark regions. Also, histogram modification approaches show good results on varied pattern images, but these generate unintentional noises at flat regions because of the compulsive shift of the intensity distribution. Therefore, in order to sufficient corrections for both bright and dark areas, the proposed algorithm calculates the gamma coefficients using primary parameters extracted from the global distribution. And the fusion weights are adaptively determined with complementary parameters, considering the classification information of a binary segmentation. As the result, the proposed algorithm can obtain a good output about both the symmetric and the asymmetric distribution images even with severe exposure values.

• Journal of Ecology and Environment
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• 제35권3호
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• pp.227-234
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• 2012

Quercus aliena and Q. serrata are both occur as natural vegetation alongside natural freshwater bodies of the southern Korea Peninsula. Q. serrata dominates over Q. aliena as secondary forest vegetation in the present day. In order to explain these natural distributional traits of the oak species, we conducted some experiments with oak seedlings which treated with major important environmental resources, including light, moisture and nutrients, under controlled conditions. We then measured the ecological niche breadths and overlap from 15 eco-morphological characteristics. The ecological niche breadth of Q. aliena and Q. serrata were higher in terms of the nutrient factor applied, but was lower terms of light. The niche breadth of Q. serrata was wider than that of Q. aliena in light and moisture exposure. On the other hand, the niche breadth of Q. aliena was similar with that of Q. serrata in terms of the nutrient factor applied. These results imply that Q. serrata has a broader ecological distribution in over a wider variety of light and moisture environments than that of Q. alien. Ecological niche overlap between two oak species was the widest in terms of the light treatment factor applied, and narrowest in terms of moisture. This response pattern was also verified by cluster and principle component analysis. These results suggest competitive interactions between Q. serrata and Q. aliena seedlings may be higher for light resources than moisture or nutrient resources, and that Q. serrata is more shade tolerant than Q. aliena.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8901-8907
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• 2015

기존의 가로등은 배광특성 조절이 어려워 주변 환경 및 도로의 상황에 따라 빛을 고루 전달하지 못하므로, 눈부심, 농작물 결실저해 및 수면 방해 등의 광공해를 발생시키고 있는 실정이다. 본 논문에서는 이러한 문제를 해결하기 위해 주변 환경 및 도로 상황에 따라 조사되는 빛의 각도를 조절할 수 있는 새로운 구조의 LED 가로등 기구를 제안 하였다. 제안된 LED 가로등 기구는 반원구조의 형상을 갖는 각도 조절 장치를 이용하여 도로의 종류 및 특성에 따라 배광특성을 조절 할 수 있도록 하였다. 측정 및 모의실험결과 배광각도는 최소 $100^{\circ}$에서 최대 $154^{\circ}$까지 조절이 가능함을 확인하였고, 평균조도는 KS 규정의 15%를 초과하였으며, 종합 균제도는 KS 규정의 50% 이상을 초과하여 성능이 우수함을 확인할 수 있었다. 따라서 본 연구를 통하여 개발된 대용량 LED 가로등 기구는 광공해를 해소하고 광원 분포의 균제도 최적화와 눈부심을 최소화 할 수 있을 것으로 사료된다.

• 한국광학회지
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• 제33권6호
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• pp.252-259
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• 2022

투과 매트릭스 방법을 이용하여 다중모드 광섬유 출력단에서 빛의 세기 분포를 제어하는 연구를 수행하였다. 공간 빛 변조기를 이용하여 원형으로 배치된 Hadamard 고유모드 위상분포를 실험적으로 구현하고, 네 가지 위상 값 변조 방법을 통하여 다중모드 광섬유의 투과 매트릭스를 실험적으로 도출하였다. 도출한 투과 매트릭스를 기반으로 광섬유에 입사하는 빛에 공간적인 위상 분포를 사전에 적용함으로써 광섬유 출력단의 원하는 위치에 빛을 집속하고자 하였다. 다중모드 광섬유 출력단 코어의 특정 위치에서 주변 배경 신호 대비 최대 359.6배 큰 세기로 빛을 집속할 수 있었으며 다중모드 광섬유 코어 영역 전반에 걸쳐 평균적으로 104.6배 향상된 값으로 빛을 집속할 수 있었다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.466-471
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• 2009

Generally LED lamp has many advantages to compare with a general lamp, long life and no pollution matter like the mercury. Also it is excellence for color rendering and need to small consumption electric rower. However LED lamp has some disadvantages to compare to general fluorescent lamp and That is small light flux about 50% and narrow light distribution than fluorescent lamp. Therefore, to apply LED lamp in an office building, after analyze a illuminance distribution with an environment analysis and cooling, heating and light energy. The purpose of this study is to analyze light environment. light, cooling and heating energy simulation in Office building.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.708-714
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• 2001

Although LP gas has lots of advantages, there has been limitation in application for automotive engine due to the several disadvantages, such as power decrease, complex fuel supply unit, and back fire etc. However LP gas direct injection engine has possibility to solve the problems above mentioned. LEM(Light Extinction Method) was employed for analysis of spacial and temporal distribution of LP gas which is directly injected into combustion chamber under various pressure and temperature conditions. The results from CVC(Constant Volume Chamber) were compared to those of RICEM(Rapid Induction, Compression and Expansion Machine) which simulate early- and late injection of direct injection engine. LPG fuel spray is affected by temperature and pressure in evaporation characteristics but it is more benefit to direct injection engine in every way such as, fuel distribution, evaporating speed and well wetting reduction.

• Journal of Pharmaceutical Investigation
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• 제17권1호
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• pp.41-46
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• 1987

Oil in water microemulsion containing soybean oil and egg phosphatide was prepared by vacuum high shear mixing and high pressure homogenizing. The laser particle sizer, Coulter counter and photomicroscope were used to determine the particle size distribution at each cycle of homogenizing. Particularly, the laser particle sizer(dynamic light scattering method) was applied to the study of particle size distribution behavior below $1\;{\mu}m$. It was found that the particle size distribution below $1\;{\mu}m$ was shifted to lower size range as the number of passing cycle was increased. Beyond the 7th cycle, however, the particle size distribution was not varied.