• Current Research on Agriculture and Life Sciences
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• v.6
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• pp.19-24
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• 1988

The present experiment was undertaken to study the influence of light intensity on plug establishment of zoysia-82, chewings fescue and red fescue. The results obtained are summarized as follows : In chewings fescue and zoysia-82, plant height and leaf length were increased and leaf width was decreased by reducing light intensity. But in red fescue, plant height and leaf length measured at 90 and 120 days after plugging under 9% of incident light were shorter than those under 30% of incident light. Percent ground cover was decreased by reducing light intensity in chewings fescue, red fescue and zoysia-82. Each part of dry weight in three species was getting lighter by reducing light intensity. Decrease of light intensity in zoysia-82 causes increasing chlorophyll a, b, and total chlorophyll content. But red fescue and chewings fescue had the most plentiful chlorophyll under 30% of incident light. Chewings fescue and red fescue had the lowest concentration of chlorophyll a/b under natural light intensity. But zoysia-82 had the lowest concentration of chlorophyll a/b under 30% of incident light. Tillering number of chewings fescue and red fescue was decreased by reducing light intensity. Internode length of zoysia-82 was longer in the order of : 1) 30% of incident light, 2) natural light, 3) 9% of incident light. And internode diameter was decreased by reducing light intensity.

• Journal of Biosystems Engineering
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• v.24 no.2
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• pp.115-122
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• 1999

Because of their small mass, volume, solid state construction and long life, light-emitting diodes(LEDs) hold promises as a lighting source for intensive plant production system. Spectral characteristics and light intensity of LEDs were tested to investigate their feasibility as artificial lighting sources for growth and morphogenesis control in transplant production system. Blue, green, and red LEDs had a peak-emission wavelength at 442nm, 522nm, and 673nm, respectively. Their half width defined as the difference between upper and lower wavelength in the intensity equivalent to 50% of the maximum intensity showed 26nm, 41nm, and 74nm, respectively. Photosynthetic photon flux(PPE) at the distance of 9cm under the LEDs array was measured as $235{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for red, $109{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for green, and $75{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for blue LEDs. At the same distance, green LEDs had the illuminance of 13,0001x, nine to ten times higher than those of red and blue LEDs. Red, green, and blue LEDs at a distance of 9cm had the irradiance of $46W{\cdot}m^{-2},\;19W{\cdot}m^{-2},\;8W{\cdot}m^{-2}$, respectively. Light intensity of blue, green, and red LEDs increased linearly in proportion to the magnitude of the current applied to the operating circuit. Thus the light intensity of LEDs was controlled by the applied current in operating circuit.

• Fisheries and Aquatic Sciences
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• v.26 no.8
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• pp.514-523
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• 2023

The visible threshold of Oreochromis niloticus responded to high light intensity under short wavelengths, whereas the response to low light intensity under long wavelengths was low, with a minimum visual threshold of 574 nm of LED lights. Movement distance of O. niloticus was dropped at 31℃ and increased abnormally at 37℃ under natural light. Comparing movement distance under red (622 nm) and green (518 nm) lights of LED, movement distance and swimming speed under red and green lights were higher than under natural light. However, the movement distance decreased rapidly at 31℃ under red light and lowest at 33℃ under green light. After that, there was a tendency to adapt to high water temperatures gradually. Consequently, red and green lights may be recommended for O. niloticus's aquaculture because the red and green lights have a positive effect on growth performance, survival rate, and metabolism, as shown in previous studies. It is necessary to control the water temperature below 32℃ because abnormal behavior above 32℃ revealed under red and green LED lights and natural light.

• Journal of Biosystems Engineering
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• v.29 no.4
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• pp.329-334
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• 2004

This study was conducted to investigate the characteristics of transmittance spectrum of Korean red ginseng using VIS/NIR spectroscopy. The results of this study were as follows; Light intensity affected the characteristics of the spectrum. For over 40% light intensity, the first and second peaks appeared at 700nm and 1,100nm, respectively. For the 20% light intensity, the first and second peaks appeared at 800nm and 1,100nm, respectively. Thus, the typical color characteristics of halogen lamp were similar to each other if over 40% of maximum light intensity power, otherwise it was not. Transmittance spectrum showed different characteristics at different portions of red ginseng. Normal red ginseng showed strong intensity at the first peak around 700nmbecause of reddish internal tissue. However, an internal white core red ginseng showed weak peak-intensity due to whitish internal tissue. There was no significant difference in the second peak at 800nm for the different internal qualities. Third peak at 900nm showed somewhat difference by internal qualities but it was difficult to find significant trend. To separate the differences of the internal qualities, intensity differences between peaks were used. It was possible to classify normal red ginseng by the differences of "peak 1 -peak 2" and "peak 1 - peak 3". In addition, shift of the first and the third peaks in the spectrum could separate normal red ginseng from others.ginseng from others.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.319-323
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• 2015

This study investigated the effects of the light conditions on the productivity of scenedesmus dimorphus in the continuous mass cultivation system. To compare the algal productivity according to the light conditions, S. dimorphus was cultivated continuously under the wide range of light intensity(200-600 PPFD) and various light wavelength(white light and red-blue mixed light). After 100 days of cultivation under the different light intensity, the productivity of S. dimorphus increased as light intensity decreased. So, the productivity was maximized as 100 mg/L/d when light intensity was 200 PPFD. In case of light wavelength, the productivity of S. dimorphus was enhanced about 20% with the white light compared to that of the red-blue mixed light. Consequently, the optimal light conditions for the continuous mass cultivation of S. dimorphus were 200 PPFD as light intensity and white light as light wavelength.

• Korean Journal of Environmental Agriculture
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• v.32 no.2
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• pp.123-127
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• 2013

BACKGROUND: The incandescent bulb and compact fluorescent lamp are widely using as a light sources for daylength extension of chrysanthemum. But, these light sources consume a lot of electricity and have short longevity. A light-emitting diode (LED) is a semi conductor light source. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime. In this study, we investigated the intensity of red light to control flowering of chrysanthemum (Dendranthema grandiflorum cv. "Shinma") by using LEDs. METHODS AND RESULTS: The red (660 nm) and far-red (730 nm) light were irradiated subsequently to investigate photo-reversible flowering responses of chrysanthemum. The flowering of chrysanthemum was inhibited by night interruption with red light but subsequently irradiated far-red light induced the flowering of chrysanthemum. This photoreversibility, reversion of the inductive effect of a brief red light pulse by a subsequent far-red light pulse, is a property of photo responses regulated by the plant photoreceptor phytochrome B. Four different intensity of red light of 0.7, 1.4, 2.1, and $2.8{\mu}mol/m^2/s$ (PAR) were irradiated at growth room in order to determine the threshold for floral inhibition of chrysanthemum. Over $1.4{\mu}mol/m^2/s$ of the red lights irradiated chrysanthemums were not flowered. The plant length, fresh weight, number of leaves, and leaf area of chrysanthemum irradiated with red light were increased by 17%, 36%, 11%, and 48%, respectively, compared to those of compact fluorescent lamp. CONCLUSION(S): The red light and subsequential far-red light showed that the photoreversibility on flowering of chrysanthemum. The red light ($1.4{\mu}mol/m^2/s$ of red LEDs) and white light (50 Lux of compact fluorescent lamp) have the same effect on inhibition of flowering in chrysanthemum. Additionally, the red light increased the plant height and dry weight of chrysanthemum.

• Journal of Ginseng Research
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• v.15 no.2
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• pp.144-151
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• 1991

This study was conducted to elucidate the effects of light intensity using polyethylene (p.E) net shading on the specific gravity, red ginseng quality, sugar and saponin contents of ginseng root. The specific gravity significantly increased in the ginseng roots grown under the P.E net shading as compared with that of common straw shading. The red ginseng quality under the P.E net shading was improved in order of 10, 5, 15, 20, 30% of light intensity and the inside cavity and inside white part decreased remarkably as compared with those of common straw shading. The ginseng roots grown under the P.E net shading at 10% and 15% light intensity showed a significant increase in the total sugar content but a significant decrease in the reducing sugar content at 15% light intensity as compared with those of common straw shading. The amount of total saponin of ginseng roots was increased under the P.E net shading at high light intensity as compared with that of common straw shading and the ginseng roots grown under the P.E net shading at 10% light intensity showed an increase in the diol group saponin but the ratio of PT/PD was decreased. Extract contents of ginseng root under the P.E net shading was higher than those of common straw shading and the roots grown under the P.E net shading at 15% and 20% light intensity resulted in a remarkable increase in extract contents.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.125-130
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• 1995

Observations on the seedling growth of red pepper responding to different temperature(10, 20, 3$0^{\circ}C$) and light intensity(5, 15, 25 klux) were made in the growth Chamber during 7 weeks. The results obtained were as follows; 1. Best results of the combinations of temperature and light intensity were obtained from the combinated treatment of 3$0^{\circ}C$ and 25klux. At all of the temperature levels in this experiment, the more the light intensity is high, the more the growth is favor, but at low temperature below 2$0^{\circ}C$ and low light intensity below 15 klux, the growth of red pepper seedlings was decreased markedly. 2. Multiple regression polynomial equations of the characteristics of red pepper seedlings grown in the different combinations of temperature and light intensity fitted well in the plant height, number of leaves, leaf area, stem dry weight and shoot dry weight. 3. Multiple regression polynomial equation to the shoot dry weight was partial differentiated and diagrammatized the response surface using its theoretical value. Light intensity affected more to the shoot dry weight in the temperature below 2$0^{\circ}C$ but above 2$0^{\circ}C$ the role of the temperature showed greatly influence however, interaction effects of light intensity and temperature showed strongly.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1222-1228
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• 2006

Two kinds of Haematococcus pluvialis cells (green vegetative cells cultivated under optimal cell culture conditions and red cyst cells maintained under high light stress conditions to induce astaxanthin production) were used to investigate the protein expression profiles by two-dimensional electrophoresis, image analysis, and peptide mass fingerprinting. The cellular accumulation of astaxanthin was evident after exposure to high light intensity and reached the maximum cellular level after 78 h of high light stress. In a 2-D electrophoresis analysis, 22 proteins were upregulated over 2-fold in the red cyst cells when compared with the green vegetative cells and selected for further analysis by chemically assisted fragmentation (CAF)-MALDI-TOF sequencing to identify the protein functions. Among 22 different spots, several key enzymes specific to the carotenoid pathway, including isopentenyl pyrophosphate isomerase (IPP) and lycopene $\beta$-cyclase, appeared in H. pluvialis after exposure to high light intensity. Therefore, IPP and lycopene $\beta$-cyclase would appear to be involved with carotenoid accumulation in the cytoplasm, as these peptides were preferentially upregulated by high light intensity preceding an increase in carotenoid, and only these forms were detected in the red cyst cells.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.89-92
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• 2004

The effects of different light quality on the change of membrane potential difference (PD) of the guard cell in the intact leaf have been investigated. The mombrane PD was about -5.5 mV by white light of 600 $\mu$moles $m^{-2}\; s^{-1}$. The mean PD of change caused by red light was about -5.2 mV at the light intensity of 80 $\mu$moles $m^{-2}\; s^{-1}$. Membrane PD of guard cells in response to blue light was saturated at low light intensity. However, red and green light enhanced the change of membrane PD of guard cells with increasing intensity. In green light the biggest change of memrane PD was around -4 mV, whereas, with blue light the change of of memrane PD was around -2 mV. Accordingly, the membrane PD of guard cell showed the different degree of hyper-polarization by each wavelength.