• 한국환경과학회지
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• 제15권12호
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• pp.1103-1107
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• 2006

Iris odesanensis Y.N. Lee is one kind of species among 54 endangered plant species designated by the Ministry of Environment in Korea. It is very rare native plant throughout the country. Therefore, this study was conducted to investigate the native Iris odesanensis in Mt. Naeyon for their distribution and ecological characteristics. They were mostly distributed mid-slope of the mountain from 443m to 498m altitude. They were located lower part of valley and provided enough humid condition. They had proper light and humidity conditions as they faced south south west, south south east, and south. They were also located at the places deciduous woody plants were distributed for proper light conditions for spring blooming. Iris flowered to use light at the period before the trees thickly covered with foliage. However this unfavorable light condition caused low percentage as 7.04% of blooming individuals in this study. In herbaceous, Vioia chaerophylloides(Regel) W. Hocker, Carex siderosticta Hance, Erythronium japonicum Decne., Oxalis obtriangulata Max., Hepatica asiatica Nakai, Lilium tsingtauense Gilg et cetera were appeared well. We propose that proper pruning of upper branches of the deciduous trees is needed for suitable light condition of management of native sites.

• 대한안전경영과학회지
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• 제12권3호
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• pp.207-214
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• 2010

The picking process in distribution center is one of the most difficult and time-consuming process. The improvement of picking productivity is a core element which decides efficiency of the distribution center. The time to shipping on vehicles from receiving depends on the arrangement of items or picking methods. The Pick to Light system typically is used to improve the efficiency of order picking. In some cases the layout design of Pick to Light system has been performed rather than scientific analysis by a common experience. Therefore, this study analyzed the impact of picking performance by the zone arrangement method in order picking process of Pick to Light system.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.247-255
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• 2012

Daylighting has a very effective role in reducing power consumption and improving indoor environments in office buildings. Previously, it was not under consideration as a major source of renewable energy due to poor reliability in the design. Optical fiber as a transmission medium in the daylighting system demands uniform distribution of light to solve cost, heat, and efficiency issues. Therefore, this study focuses on the uniform distribution of sunlight through the fiber bundle and to the interior of the building. To this end, two efficient approaches for the fiber-based daylighting system are presented. The first approach consists of a parabolic mirror, and the second approach contains a Fresnel lens. Sunlight is captured, guided, and distributed through the concentrator, optical fibers, and lenses, respectively. At the capturing stage, uniform illumination solves the heat problem, which has critical importance in making the system cost-effective by introducing plastic optical fibers. The efficiency of the system is increased by collimated light, which helps to insert maximum light into the optical fibers. Furthermore, we find that the hybrid system of combining sunlight and light emitting diode light gives better illumination levels than that of traditional lighting systems. Simulation and experimental results have shown that the efficiency of the system is better than previous fiber-based daylighting systems.

• 수산해양기술연구
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• 제55권3호
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• pp.190-197
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• 2019

This study investigated the luring effect of the sardine bait, which is used to catch octopus with pot, as the preliminary study for the development of alternative bait for octopus pot. The soaking time for bait was divided into "5 days or less" and "11 days or longer" The number of times octopus entered the pot with bait and the empty pot was investigated under dark adaptation and light adaptation processes and the distribution of tank section was investigated under light adaptation process. The case of "11 days or longer" sardine soaking time showed higher rate of distribution in the section of pot with bait compared to the case of "5 days or less" In the case of "5 days or less" soaking time, the number of times the octopus entered the pot with bait was similar to that it entered the pot without it even during dark adaptation and light adaptation. However, in the case of "11 days or longer", the octopus entered the pot with bait more quickly than the pot without bait and more frequently during dark adaptation hours. There were cases where the octopus did not enter any pot. In the case of "5 days or less", with less decomposition of baits, the octopus entered the empty pot more during light adaptation process, and it appeared that the pot was used as a hideout.

• 한국광학회지
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• 제35권1호
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• pp.18-23
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• 2024

미술관 등 전시 공간에서의 조명은 바닥보다는 주로 전시물이 붙어 있는 벽면에 비춰져야 한다. 일반적으로 사용되는 LED 조명은 LED에 확산판이 결합된 형태로서 각도별 배광 분포가 일정한 램버시안 광원에 가까우며, 수직 입사가 이뤄지는 바닥면에 조명이 집중된다. 따라서 이러한 일반적 형태의 조명 방법은 벽면을 조명하기에는 적합하지 않으며, 벽면에 조명을 집중시키기 위해서는 각도별 배광 분포 중 각도가 큰 영역에서의 광량이 커지도록 해야 한다. 본 연구에서는 광원에서의 발산각을 180도로 확산시키기 위해 초광각 변환기를 사용하는 조명 광학계에 대해 논의하고자 한다.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1128-1128
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• 2001

We have developed a probe for measuring the light levels inside illuminated fruit. The probe has minimal effect on the light levels being measured and enables the sampling of the light flux at any point within the fruit. We present experimental light extinction rates within apple, nashi, kiwifruit, and mandarin fruit. Moving from the illuminated side to the far side of the fruit, the extinction level follows an initial power law decay as the light diffuses into the fruit then reduces to an exponential decay through the rest of the fruit. Significant variations in the rates of light extinction are found in the core, skin and differing flesh regions. Monte Carlo simulations of the light distribution in fruit, which use scattering and absorption coefficients for the diffusely scattering tissue, and boundary conditions for the skin effects, produce results that follow the experimental results closely.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.789-793
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• 2003

This study focused on the optimization of the illumination method for efficient use of light energies in a photobioreactor. In order to investigate the effect of radiator position, a model simulation study was carried out using Synechococcus sp. PCC 6301 and an internally radiating photobioreactor as a model system. The efficiency of light transfer in a photobioreactor was analyzed by estimating the average light intensity in a photobioreactor. The simulation result, indicate that there exists an optimal position of internal radiators, and that the optimal position varies with radiator number and cell concentration. When light radiators are placed at the optimal position, the average light intensity is about 30% higher than that obtained by placing radiators at the circumstance or center of a photobioreactor. The method presented in this work may be useful for improving light transfer efficiency in a photobioreactor.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.25-34
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• 2019

최근, 출력전압의 제어가 가능하고 양방향 운용이 가능한 PWM(Pulse Width Modulation) 정류기가 도입되고 있다. 그러나, PWM 정류기가 적용될 경우, 전력계통측에서 사고발생하면, 회생전력에 의한 사고전류 공급으로 기존의 사고전류 크기 및 방향이 바뀔 가능성이 있다. 또한, 경전철용 급전시스템에서는 장거리 지점에서 사고가 발생하는 경우, 사고전류의 크기가 크게 감소되고, 부하전류와 비슷하거나 더 작은 경우가 발생할 수 있기 때문에 이에 대한 적절한 보호협조 운용 방안이 필요한 실정이다. 따라서, 본 논문에서는 상기의 문제점들을 해결하기 위하여, 경전철용 LVDC 배전선로의 보호기기 운용 방안을 제안한다. 구체적으로는 LVDC 배전선로에서의 거리 및 단락저항별 사고특성을 분석하여, 다양한 조건에서 사고를 적절하게 판별하는 직류선택계전기의 보호협조 운용방안을 제안한다. 또한, 배전계통 상용 해석 프로그램인 PSCAD/EMTDC를 이용하여 AC 계통, PWM 정류기, LVDC 배전선로로 구성된 경전철용 급전시스템의 모델링을 제시한다. 한편, 제안한 보호협조 알고리즘과 모델링을 이용하여 LVDC 배전선로의 보호기기 특성을 분석한 결과, 제안한 운용방식에서는 전류 경사각의 급격한 감소를 판정하는 보호요소를 추가한다. 따라서, 사고지점의 단락저항이 높거나 장거리 선로인 경우에도, 보호기기가 사고전류와 부하전류를 적절히 판별할 수 있어, 본 논문에서 제안한 보호협조 운용알고리즘의 유용성을 확인하였다.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.145-152
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• 1999

This paper presents the principle and experimental results of a non-contact surface roughness measurement by means of screen projected pattern of lase beam reflected from a polished surface. In the reflected laser beam pattern especially from a fine surface like ground or polished one, light intensity varies from the center fo the image to its boundary as the Gaussian distribution. The standard deviation of a light intensity distribution is assumed to be a good non-contact estimator for measuring the surface roughnes, because the light reflectivity is known to be well related with the surface roughness. This method doesn't need to discriminate between the specularly reflected light and the diffusely reflected one, whereas the scattered laser intensity method must do. Nor it needs to adjust the change of light intensity caused by environmental lights or specimen materials. Reflected laser beam pattern narrowly spreads out in the vertical direction to tiny scratches on the polished surface due to abrasives. The deeper the scratch the more the dispersion, which means the rougher surface. The standard deviation of the pattern is nearly in proportion to the surface roughness. Measurement errors by this method are shown to be below 10 percent compared with those obtained by a common contact method. The inclination of measuring unit from the normal axis causes the measurement errors up to 10 percent for an angle of 4 degree. Therefore the proposed method can be used as an on-the-machine quick roughness estimator within 10 percent measurement error.

• 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.