• Journal of Photoscience
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• v.2 no.1
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• pp.31-35
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• 1995

Light signals in the form of intensity gradient, propagation direction, and wavelength elicit diverse mechanical responses ("photomechanical responese") in most organisms. The single cell ciliates, Stentor coeruleus and Blepharisma japonicum, are particularly sensitive to the light of visible wavelengths. In this paper, the way in which the seemingly sophisticated light signal transduction is triggered by the photosensory apparatus will be described in terms of the photoreceptor structure and photochemical function.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1998.06b
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• pp.122-128
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• 1998

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.232-239
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• 2016

The objective of this study was to examine the effect of photoperiod and light intensity of RBW LED (red:blue:white = 2:1:1) on the growth of Taraxacum coreanum Nakai in a fully artificial light type plant factory. 3 photoperiods and 4 light intensity were used respectively in a fully artificial light type plant production system. Plants were cultured with three photoperiods and four light intensity regimes (conditions) for 270 and 120 days, respectively, using nutrient film technique (NFT) or aeroponics culture methods. For each photoperiod, the total leaves per plant harvested 8 times in all cultivation period was 224 in the 16/8(day/light) photoperiod that had no significant difference from 220 in the 12/12 photoperiod and the lowest number of leaves was 151 occurred in the 8/16 photoperiod, which means that the longer photoperiod, the more leaves harvest. Total fresh weight of above ground was the high in order of in 16/8 photoperiod as 125g, 12/12 photoperiod as 91g, 8/16 photoperiod as 56g. For each light intensity, the total leaves per plant harvested 4 times in all cultivation period was the great in order of $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 123, $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 107, $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 95, $50{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 56 which was the smallest number of total leaves harvest. Total fresh weight of above ground per plant was the high in order of $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 43.6g, $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 34.6g, $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 32.2g, $50{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as 18.2g. From these results, it was concluded that photoperiod of 16/8 and light intensity at $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ can be used as the light condition of RBW LED (red:blue:white = 2:1:1) for optimal growth of Taraxacum coreanum Nakai in a fully artificial light type plant factory.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.12a
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• pp.227-233
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• 1999

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.409-417
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• 2001

The purpose of this study was to investigate the influence of light irradiation over self-priming adhesive on dentin bonding. After acid etching the exposed dentin, a self-priming adhesive (Prime&Bond$^{\circledR}$NT dental adhesive system Dentsply DeTrey, GmbH, Konstanz, Germany) was applied and light irradiation was done for 20 sec with regular intensity (600 mW/$\textrm{cm}^2$) in group I and for 3 sec with ultra-high intensity (1930 mW/$\textrm{cm}^2$) in group III. No light irradiation was done over self-priming adhesive in groups II and IV. Composite resin was added on the self-priming adhesive and irradiated for 40 sec with regular intensity (600 mW/$\textrm{cm}^2$) in groups I and II and for 3 sec with ultra-high intensity (1930 mW/$\textrm{cm}^2$) in groups III and IV. To see the effect of light curing time on dentin bonding, another 3 group specimens were prepared. Without light-irradiation over self-priming adhesive, added composite resin was irradiated for 3, 6, or 12 sec with ultra-high intensity light. After bonded specimens were stored in 37$^{\circ}C$ distilled water for 24 hours, shear bond strength were measured using a universal testing machine (4202, Instron, Instron Co., U.S.A.) and fractured surfaces were examined under a stereomicroscope (SZ-PT Olympus, Japan). Statistical analysis were done with one-way, two-way ANOVA and chi-square test. The results were as follows : 1. The shear bond strengths from the groups irradiated over self-priming adhesive were significantly higher than those from the groups without irradiation (p<0.05). 2. There was no significant shear bond strength difference between regular intensity light irradiation groups and ultra-high intensity ones (p>0.05). 3. There was no significant shear bond strength difference among various irradiation time groups with ultra-high intensity ones (p>0.05). 4. In stereomicroscopic examination of fractured surfaces, adhesive-cohesive mixed failure mode was mostly seen in all groups, and there was no significant difference in failure mode among groups (p>0.05).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.558-562
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• 1986

The purpose of this study is to find the light intensity which induces maximum gathering rate and to observe the variation of the gathering rate both in daytime and at night by using marbled sole, Limanda yokohamae (Gunther). An experimental tank ($360L{\times}50W{\times}55H\;cm$) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Six artificial light sources were prepared by combination of two light bulbs (5W, 150W) and seven filters. During the experiment water depth was maintained 50 cm level in the tank. The tank was marked into six longitudinal sections each being 60 cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 1.9 lux ($1.2{\sim}2.9\;lux$) in the daytime and 0.7 lux ($0.5{\sim}1.1\;lux$) at night. The variation of the gathering rate of fish in illumination time was small and comparatively fluctuated with stability.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.37-43
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• 1989

The purpose of this study is to find the light intensity which induced maximum gathering rate and to observe the variation of the gathering rate both in daytime and at night by suing Rudder fish, Girella punctata(Gray). An experimental tank(360L*50W*55H cm) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Eight artificial light sources were prepared by combination of three light bulbs(10W, 60W, 100W) and eight filters. During the experiment water depth was maintained 50cm level in the tank. The tank was marked into six longitudinal sections each being 60cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 60 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 2.98 lux(1.90-4.40 lux) at daytime and 298.56 lux(188.44-444.96 lux) at night. The variation of the gathering rate of fish in illumination time was great and irregularly fluctuated, but did not show any definite pattern. It was somewhat difference between daytime and night.

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.201-205
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• 2015

This paper dealt with the condensing technology of an LED light source that uses a parabolic reflector to replace a searchlight equipped with a xenon lamp. A ray-tracing simulation was conducted to analyze the influence of the diameter of the reflector and the size of the light source on light condensing. The combination of a parabolic reflector with a diameter of 620 mm and a focal distance of 220 mm, and a 9 mm multi-chip package (MCP) with a luminous flux of 7,000 lm showed the narrowest beam angle. The luminous intensity at the center was measured at 7.7×10⁶ cd. The distance between the light source and the point where the illuminance was 1 lx was calculated to be 2.8 km. The power consumption of the system was 95 W, which is only 9.5% of that of the 1 kW xenon searchlight, and the beam angle was 1.03°. In a site experiment, it was confirmed that the light ray reflected from the LED searchlight proceeds forward without any diffusion because of the narrow beam angle.

• Journal of Photoscience
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• v.5 no.1
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• pp.17-22
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• 1998

Changes of chlorophyll fluorescence and xanthophyll cycle pigment contents in maize leaves were investigated dunng desiccation in darkness or in the light. In darkness, a drastic dehydration of detached maize leaves down to 50% relative water content (RWC) affected photochemical efficiency of photosystem II (Fv/Fm) and pht)tochemical quenching (qP) only slightly. In contrast, desiccation in the light with a moderate intensity led to a pronounced reduction in Fv/Fm with a Fo quenching when RWC was greater than 70%. This reduction in Fv/Fm could be recovered in darkness under hutrod condition. In leaves with RWC below 70%, significant reduction in Fv/Fm was accompanied by an increase of Fo, which could not be reversed within 5 h in darkness under humid condition. The nonphotochemical quenching increased during desiccation in the light with a concomitant rise in zeaxanthin at the expense of violaxanthin. Pretreatment with dithiothreitol (DTT), an inhibitor of zeaxanthin synthesis, inhibited the development of nonphotochemical quenching and prevented the xanthophyll interconversion during desiccation in the light. These results suggest that even light with a moderate intensity becomes excessive under dehydration and zeaxanthin-associated photoprotection of photosynthetic apparatus against photodamage is involved, but the protection is not complete against severe desiccation.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.203-209
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• 2010

This study was performed to investigate photosynthetic responses of 4 foliage plants in relation to light intensity, carbon dioxide concentration, and media, and to select efficient plants for the indoor environment control based on the results. Four foliage plants used in this study included Syngonium podophyllum, Schefflera arboricola cv. Hong Kong, Dieffenbachia amoena, and Dracaena deremensis cv. Warneckii Compacta. The plants cultivated in two different growth media, peatmoss and hydroball, and subjected to various light intensities (0, 30, 50, 80, 100, 200, 400, and $600\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD) and $CO_2$ levels (0, 50, 100, 200, 400, 700, 1000, and $1500\;{\mu}mol{CO_2}{\cdot}mol^{-1}$). As a result of the photosynthetic rate of foliage plants according to change of light intensity and $CO_2$ levels, Schefflera arboricola and Dieffenbachia amoena showed high apparent quantum yield, which stands for the photosynthetic rate under low light intensity, and both plants also recorded higher photosynthetic rate under high $CO_2$ concentration compared to the other two indoor plants. Dracaena deremensis showed the lowest photosynthetic rate under the low light intensity or high $CO_2$ concentration. There were inconsistent results in photosynthetic rate of foliage plants grown in peatmoss or hydroball. Higher photosynthetic rate was observed in Schefflera arboricola with peatmoss rather than hydroball as light and $CO_2$ concentration increased. However, hydroball had a positive effect on Dieffenbachia amoena in terms of photosynthetic rate. In case of Syngonium podophyllum, peatmoss induced higher photosynthetic rate according to increased light intensity, but there was no effect of media on the rate under various $CO_2$ treatements. In contrast, media did not affect to photosynthetic efficiency of Dracaena deremensis subjected to various light intensities and the rate of Dracaena deremensis with peatmoss was a little high when $CO_2$ concentration increased. In conclusion, potential plants for the indoor air pulification and environmental control were Schefflera arboricola and Dieffenbachia amoena because they showed high photosynthetic rate under typical indoor conditions, low light intensity and high $CO_2$ concentration.