• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.58.3-58.3
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• 2019

Optical intensity interferometry, developed in the 1950s, is a simple and inexpensive method for achieving angular resolutions on microarcsecond scales. Its low sensitivity has limited intensity interferometric observations to bright stars so far. Substantial improvements are possible by using avalanche photodiodes (APDs) as light detectors. We present here the results of laboratory measurements with a prototype astronomical intensity interferometer using APDs in continuous ("linear") detection mode - arguably, the first of its kind. We used two interferometer configurations, one with zero baseline and one with variable baseline. Using a superluminous diode as light source, we unambiguously detected Hanbury Brown-Twiss photon-photon correlations at very high significance. From measuring the correlation as function of baseline, we measured the angular diameter of the light source, in analogy to the measurement of the angular diameter of a star. Our results demonstrate the possibility to construct large astronomical intensity interferometers that can address a multitude of astrophysical science cases.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.3
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• pp.353-363
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• 2007

To differentiate temperature effect from the light intensity effect on the formation of secondary products during the photooxidation of toluene-$NO_x$-air mixtures, steady-state air temperature was changed from $20^{\circ}C\;to\;33^{\circ}C$ at the same light intensity of $0.39min^{-1}$ in an indoor smog chamber. Smog chamber consisted of 64 blacklights and a $5.8m^3$ reaction bag made of Teflon film. Air temperature was controlled by an air-conditioning system. The starting time for rapid conversion of NO to $NO_2$ was slightly delayed with decreasing air temperature. In contrast to light intensity effect, the ozone formation time and the ozone production rate were insensitive to air temperature. Although the formation time for secondary organic aerosols was not changed, the particle number concentration increased with temperature. However, the newly formed secondary organic aerosol mass at lower temperature was higher than that at higher temperature. Since light intensity significantly affected the starting time and quantity of ozone and aerosol formation, it is considered that the temperature could contribute partly the quantity of aerosol formation during the photooxidation of toluene-$NO_x$-air mixtures.

• Horticultural Science & Technology
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• v.17 no.1
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• pp.29-32
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• 1999

This experiment was conducted to investigate the effect of different levels of shading (0, 35, 55, 75, 95% to incident sunlight) on the growth of Hedera rhombea Bean and Pachysandra terminalis Sieb. et Zucc. in order to determine optimum light intensity for ground cover plants. H. rhombea showed a upright growth type under 95% shading and P. terminalis was highest under 35% shading. Number of branches was not significantly affected by shading levels. Stem diameter and length were reduced under shading from 35% to 95%. Leaf growth was vigorous under 35% and 55% shade condition. Leaves became longer with decreasing light intensity, but shorter in 95% shading than control. There was a slight trend that total chlorophyll and chlorophyll a, b contents increased with decreasing light intensity, and so did chlorophyll a/b ratio. Fresh and dry weight of both plants were higher under 35, 55, and 75% shading than control and 95% shading. Specific leaf weight tended to decrease with reduction of light intensity. Thus, optimum light intensity for growth of them may be 35 and 55% shading of incident sunlight. In addition, it is possible to grow them under even 75% shading of incident sunlight.

• Journal of Ginseng Research
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• v.17 no.3
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• pp.240-245
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• 1993

This study was conducted with ginseng plants to investigate photosynthetic response to changes of light intensity and leaf temperature. $CO_2$ uptake in diurnal course was highest in the first phase (8 00~5 : 30 Am.) on May 30, 1992. In $CO_2$ uptake related to stomatal conductance, these relationship was synchronized in diurnal course, but relationship between TEX>$CO_2$ uptake and intercellular $CO_2$ concentration in diurnal course was synchronized oppositely. Leaf temperature and light intensity at the highest $CO_2$ uptake were in the range of 23~$24^{\circ}C$) and 95$\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ , respectively. In response to an increasing light intensity under a constant leaf temperature ($18^{\circ}C$), $CO_2$ uptake was increased throughout the light intensity sequence up to 250$\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ When $CO_2$ uptake was measured with a series of leaf temperature under a constant light intensity (250 $\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ uptake was highest at $18^{\circ}C$ as a 4.1$\mu$mol.$m^{-2}$.$s^{-1}$), $CO_2$ . Similar changes were also observed in stomatal conductance and intercellular $CO_2$ concentration. Evidences from several approaches indicate that synchronization of $CO_2$ uptake, stomatal conductance and intercellular $CO_2$ concentration were closely inter-related and changes of leaf temperature iuluenced the photo-response in photosynthetic processes.

• Animal cells and systems
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• v.14 no.2
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• pp.125-128
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• 2010

This study investigated the effect of different light intensities on first feeding of chub mackerel Scomber japonicus larvae. Fertilized eggs, obtained from LHRHa-induced spawning of captive broodstock, were stocked (60 larvae/l) into twelve 30-1 aquaria under light intensities of 0, 100, 200, 500 and 1000 lx, with three replicate aquaria per treatment. Temperature was maintained at $20^{\circ}C$ and salinity was 35 psu. Larvae were fed the rotifer Brachionus rotundiformis at a density of five rotifers/ml. Feeding incidence was measured as the percentage of larvae with prey in the digestive tract. Feeding intensity was evaluated as the number of prey in the digestive tract of the larvae. Larvae fed in darkness (0 lx) had significantly lower (P < 0.05) feeding incidence ($13{\pm}0.05%$ larvae with prey) and feeding intensity ($1.00{\pm}0.05$ rotifers per larva) than those larvae fed at 100 ($30{\pm}0.07%$, $1.17{\pm}0.09$ rotifers per larva), 200 ($43{\pm}0.08%$, $1.24{\pm}0.11$ rotifers larvae$^{-1}$), 500 ($53{\pm}0.08%$, $1.48{\pm}0.14$ rotifers per larva) and 1000 lx ($60{\pm}0.08%$, $1.38{\pm}0.13$ rotifers per larva). The feeding incidence of S. japonicus larvae increased with light intensity while feeding intensity showed no significant difference (P > 0.05) between light treatments.

• Korean Journal of Plant Tissue Culture
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• v.22 no.2
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• pp.71-76
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• 1995

The effects of light on the activities of several antioxidative enzymes, catalase (CAT), superoxide dismutase(SOD), ascorbate oxidase(AO), and peroxidase(POD) were examined in the hairy root cultures of Phytolacca esculenta van Houtte induced by Agrobacterium tumefaciens $A_4$T. Activities of CAT, SOD, and AO were significantly decreased with incresing light intensity (500-2,000 lx). The activity of AO under high light condition (2,000 lx)was decreased by 92% compared to the dark condition. The activities of glutathoine peroxidase (GPO), ascorbate peroxidase (APO) and general POD were increased under lower light intensify below 500 lx. The activity of GPO under 2,000 lx was decreased by 85% compared to the dark condition. The activities of antioxidative enzymes were more decreased in blue light (400-500nm). The activities of antioxidative enzymes in blue light intensity were increased in lower light intensity below 30 lx, but decreased 21-70% under 200 lx. The activity of AO was decreased by 70% under 200 lx with increasing blue light intensity. Our results suggest that the activities of antioxidative enzymes in hairy roots might be inhibited by endogenous oxidants generated under the high blue light conditions.

• Korean Journal of Organic Agriculture
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• v.27 no.2
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• pp.161-171
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• 2019

A light-emitting diode (LED) is most efficient in terms of economic benefits. The aim of the present study was to evaluate the effects of LED lighting intensity on milk production, milk composition, and the immune response of Holstein cows. Thirty-eight lactating cows were assigned to four experimental groups: control group (exposed natural daylight without LED light) and three LED treatment group (50 lux; natural daylight and 6 h LED light of 50 lux intensity, 100 lux; natural daylight and 6 h LED light of 100 lux intensity, 200 lux; natural daylight and 6 h LED light of 200 lux intensity). There was a significant effect on the decrease ratio in milk production in 200 lux group. Lactose was significantly increased in 100 lux than the other LED treated groups. In addition to the hemolytic biochemical analysis, AST and β-HB were significantly increased in the 50 lux than the other groups. Prolactin and IGF-1 levels were significantly increased in 200 lux compared to other groups. Besides, cortisol was significantly higher in 50 lux and lowered in the 200 lux than the control, while IgA and IgG were not significant among the groups. Therefore, it was concluded that LED lighting intensity had some impact on blood parameters and immune responses in dairy cows with increased milk production.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.57-63
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• 2015

Recently, LED is widely used in the kinds of display devices or lighting. In this paper, we fabricated LED chamber light for naval vessels to replace to conventional chamber light using incandescent lamp. The LED package of chamber light was designed with luminous intensity of 5.5 cd, color temperature of $6,000{\pm}500K$, forward voltage of 3~3.2 V and input current of 60 mA. A LED module was composed of 36 LED packages and metal PCB. The VF and luminous intensity of LED package were getting down when temperature increased. The temperature of LED chamber light was measured by changing the number of LED package and applied current for one hour when an electric current flow. The heat transfer capability have been improved by using metal PCB. The power consumption of LED chamber light reduced by 86% compared to the conventional chamber light using incandescent lamp.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.374-382
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• 2006

Purpose: This study was designed to investigate the present conditions of illumination techniques in dental clinics in order to contribute improvement of operating environment. This study also aimed exploring qualitative and quantitative luminous intensity required for color temperature in dental clinic illumination, which was a critical part of esthetic dentistry. Materials and methods: A total of forty-eight local dental clinics were selected for sampling a) luminous intensity, and b) color temperature. The author measured the luminous intensity and the color temperature with lux meter and color meter respectively between 12pm and 2pm. The dental unit chair placed in the general operation positions were kept the distance 60 cm then all dental units were measured three times and averaged. The author measured the luminous intensity and color temperature with both common dental operating light and then without operating light in different office environments. The study was conducted under three conditions: 1 artificial illumination in clear day light 2. artificial illumination in cloudy day light, and 3. artificial illumination alone. Results : The results obtained were as follows. 1. The average luminous intensity in dental clinic lighting was 425 lux which was not sufficient to produce the optimal shade of the patient's teeth. Furthermore, the average luminous intensity even in full operating lighting was 9532 lux which fell short of the required level of 10,000 lux. 2. The average color temperature of all dental clinics surveyed was 5169 K which met the optimal range. However, only 33.3% fell in the correct region between 5,000-5,500 K as 25% were over 5,500 K and 41.6% were below 5,000 K. As a result, 66.7% were under insufficient color temperature conditions. 3. The dental unit chair placed next to a window, hence exposure to natural lighting, had significantly higher luminous intensity and color temperature compared to the dental unit chair which didn't have a window or natural lighting. 4. The data analysis revealed that only 6.3% of the dental clinic were met the standard of the average luminous intensity and color temperature.

• Korean Journal of Ichthyology
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• v.19 no.3
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• pp.185-192
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• 2007

The present experiment was carried out to study the effects of light intensity on growth, survival, caudal fin shape, body composition, skin color and blood component of river puffer, Takifugu obscurus. Four light intensities (0, 500, 1,000, 2,000 lx) were tested in duplicates for 60 days. Specific growth rate (SGR), daily feeding rate (FR) and food coefficient (FC) were reduced following to the decrease of light intensity. However in survival rate there was not significantly different among groups. The damage extent of caudal fin was increased in more strong light intensity. In body composition, moisture and crude protein were only significantly difference according to light intensity. In body color, L and a were the highest in 0 lx. In blood analysis, the content of AST, ALT, GLU significantly increased in more powerful the intensity groups. It is concluded that the supplement of low light intensity (e.g. 0 lx) recommended for the commercial scale aquaculture of river puffer in land-based tank without growth and survival retardation.