• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.3222-3226
• /
• 2000

In this study, the variations of human physiological signals(EEG and ERG) were measured on a various optic stimulation. From the analysis of the physiological signals, it was cleared that the optimum intensity of light exits at its sensing.

• Agribusiness and Information Management
• /
• v.6 no.1
• /
• pp.37-44
• /
• 2014

This study was conducted to evaluate light intensity and uniformity of two SMD (surface-mount device) type LEDs for protected crop production. A low-power (0.1 W) and a high-power (1 W) LEDs were selected and the intensity and uniformity was evaluated at different vertical (height) and horizontal (distance) intervals. When the horizontal interval of the LED bar was fixed, the light intensity increased and the uniformity decreased as the height decreased. At the 30~40 cm heights, 20~30% of the area showed $200{\pm}20{\mu}molm^{-2}s^{-1}$. As the horizontal distance of the LED bars increased, while the uniformity increased as well, the light intensity decreased. At the distances of 6~10 cm, 17~23% of the area showed $200{\pm}20{\mu}molm^{-2}s^{-1}$. When the LED bars were added to the sides, the light intensity and uniformity were generally improved. Results showed that the light intensity and uniformity depended on the height and interval of the LED bulbs; therefore, optimum arrangement for the crops interested should be determined through experiments.

• Horticultural Science & Technology
• /
• v.17 no.1
• /
• pp.29-32
• /
• 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 Environmental Health Sciences
• /
• v.28 no.5
• /
• pp.59-64
• /
• 2002

The photocatalytic decolorization of the Rhodamine B (RhB) was studied using a UV/TiO$_2$ reactor. Yakuri titanium dioxide(anatase) was used as the suspended photocatalyst and proved to be effective for decolorization irradiated with UV light (254 mm). The photocatalyzed dioxide concentrations, light intensity and air flow rates. In 0.01 mM RhB, color could be completely photodegraded after 3 hours. Absorption spectrum of an aqueous solution containing RhB showed a continued diminution of the RhB concentration in the solution bulk : concomitantly, no new absorption peaks appeared. This confirmed the decolorization of RhB, i.e., the break up of the chromopore. The optimum loaded titanium dioxide for the decolorization was 0.75 g/(equation omitted). The light intensity showed exponential decay with distance. The decay of light intensity of RhB solution showed different tendency from TiO$_2$. These results suggested that the photocatalytic decolorization of dyes may be available method for decolorizing in wastewater.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.12 no.2
• /
• pp.79-86
• /
• 1979

The phototaxis of common carp Cyprinus carpio was studied tinder laboratory conditions to find out distributional pattern of the fish under light gradient and to find the light intensity which causes the maximum gathering rate. The optimum light intensities were determined, The fish tended to escape from tile light source when the light intensity was stronger or weaker than a certain optimum value. The mean illumination intensity which caused the maximum gathering rate was 3.813lux (2.99-4.76 lux) in the daytime and 6.292 lux (5.0-7.89 lux) at night. The gathering rate of the fish could be divided into two types: reflex gathering rate and equilibrium gathering rate. The reflex gathering rate appeared quickly soon after lighting and gradually changed as time elapsed, while the equilibrium gathering rate was almost always constant.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.1
• /
• pp.35-43
• /
• 2008

Aviation obstacle lights including controller for the safe night aviation service have applied to high voltage transmission line of which height is from $60{\sim}180 m$, Fresnel lens made by Augustine Fresnel have been applied to light houses, These Fresnel lens were applied to aviation obstacle lights and have been universally used, It was reported that Fresnel lens for aviation obstacle light was used in the first place in Korea in 1987, LEDs have recently been applied to aviation obstacle lights, So, the optimum physical design is essential to the design of aviation obstacle light. In this study, optical and three dimensional modeling of LED module and globe lens were performed, And thermal analysis due to LED thermal source and service thermal condition in high voltage transmission line was performed and was analyzed comparing with experiments, The optimum design process of medium intensity LED aviation obstacle lights was constructed with three dimensional modeling, thermal analysis, and thermal experimental technique.

• Korean Journal of Medicinal Crop Science
• /
• v.10 no.1
• /
• pp.1-4
• /
• 2002

This study was carried out to know the effect of light intensity, temperature and $CO_2$ concentration on photosynthesis and transpiration in Hovenia dulcis Thunb. Light compensation point was $2.4\;{\mu}mol\;m^{-2}\;s^{-1}$ and light saturation point was $1033\;{\mu}mol\;m^{-2}\;s^{-1}$. The optimum temperature for photosynthesis was $25^{\circ}C$ at $1000\;{\mu}mol\;m^{-2}\;s^{-1}$ light intensity. $CO_2$ compensation point was 67 vpm and $CO_2$ saturation point was 707 vpm. Transpiration rate was increased to about $2\;mmol\;m^{-2}\;s^{-1}$ with increasing of light intensity to $1750\;{\mu}mol\;m^{-2}\;s^{-1}$ and to above $4\;mmol\;m^{-2}\;s^{-1}$ with increasing of temperature from $18^{\circ}C$ to $36^{\circ}C$. however It was gradually reduced as $CO_2$ concentration increased from 21 vpm to 800 vpm.

• Journal of Ginseng Research
• /
• v.6 no.2
• /
• pp.154-161
• /
• 1982

To determine the effects of mulching with the hulls of rice on the growth of the ginseng plant and changes of its growing environment-soil moisture content. subterranccan temperature and soil hardness- were investigated under different light intensity such as 5%, 10%, 20%, and 30% light transmittance rate(LTR). The results obtained were as follows; 1. Soil moisture content under the shading was decreased as the increase of light intensity, whereas it was increased about 1.5% in each plot of LTR by the mulching. 2. Suberranccan temperature under the shading was increased as the increase of light intensity. It was decreased on a hot day by the mulching but increased on a cold day. 3. Soil hardness was decreased by the mulching. 4. Sprouting date of the ginseng plants was acclerated for 7 days and sprout periods were shortened for f days by mulching compared to the non-mulching treatment. 5. Missing plant rate was increased severely as the increase of light intensity more Than 20% LTR In the non-mulching plots but did not severe in the mulching plots. Missing plant rate was decreased remarkably by the mulching. The degree of decrease was larger as the increase 6f light intensity. 6. Root yield was increased in the mulching plots compared to the non$.$mulching plots. The degree of increase was larger as the increase of light intensity. The highest yield was obtained at 20% LTR with mulching.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.8
• /
• pp.1034-1043
• /
• 2014

This study determined the effect of light intensity and photoperiod on the dry cell weight and total amount of carotenoids in four isolates of purple non-sulfur bacteria obtained from shaded and exposed microhabitats of a mangrove ecosystem in Kota Kinabalu, Sabah, Malaysia. The initial isolation of the bacteria was carried out using synthetic 112 medium under anaerobic conditions (2.5 klx) at $30{\pm}2^{\circ}C$. On the basis of colony appearance, cell morphology, gram staining, motility test, and 16S rRNA gene sequencing analyses, all four bacteria were identified as Afifella marina. One of the bacterial isolates, designated as Af. marina strain ME, which was extracted from an exposed mud habitat within the mangrove ecosystem, showed the highest yield in dry cell weight ($4.32{\pm}0.03g/l$) as well as total carotenoids ($0.783{\pm}0.002mg/g$ dry cell weight). These values were significantly higher than those for dry cell weight ($3.77{\pm}0.02g/l$) and total carotenoid content ($0.706{\pm}0.008mg/g$) produced by the isolates from shaded habitats. Further analysis of the effect of 10 levels of light intensity on the growth characteristics of Af. marina strain ME showed that the optimum production of dry cell weight and total carotenoids was achieved at different light intensities and incubation periods. The bacterium produced the highest dry cell weight of 4.98 g/l at 3 klx in 72 h incubation, but the carotenoid production of 0.783 mg/g was achieved at 2.5 klx in 48 h incubation. Subsequent analysis of the effect of photoperiod on the production of dry cell weight and total carotenoids at optimum light intensities (3 and 2.5 klx, respectively) revealed that 18 and 24 h were the optimum photoperiods for the production of dry cell weight and total carotenoids, respectively. The unique growth characteristics of the Af. marina strain ME can be exploited for biotechnology applications.

• Korean Journal of Medicinal Crop Science
• /
• v.9 no.3
• /
• pp.232-237
• /
• 2001

This study was carried out to know the effect of light intensity, temperature and $CO_2$ concentration on photosynthesis and transpiration in yacon(Polymnia sonchifolia Poepp.& Endl.). Light compensation point was ${58\;{\mu}mol\;m^{-2}\;s^{-1}}$and light saturation point was ${1708\;{\mu}mol\;m^{-2}\;s^{-1}}$. Transpiration rate was increased to about 4 mmol${m^{-2}\;s^{-1}}$ with increasing of light intensity to ${2193\;{\mu}mol\;m^{-2}\;s^{-1}}$. The optimum temperature for photosynthesis was ${24^{\circ}C}$ in air. Photosynthesis was gradually reduced as transpiration rate increased from 4 to 8 mmol ${m^{-2}\;s^{-1}}$ in different air temperature. $CO_2$ compensation point was 63 vpm and $CO_2$ saturation point was 1155 vpm and light saturation point was enhanced with increasing of $CO_2$ concentration from 350 vpm to 1300 vpm.