• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.495-500
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• 2015

Currently the fish aquaculture industry of Korea is focused on the mass culture of flatfish (Paralichthys olivaceus) and and rockfish (Sebastes schlegeli) with completely controlled culture techniques. Recently, there has been considerable interest in new species development, such as the starry flounder (Platichthys stellatus). The value of starry flounder (Platichthys stellatus) as a raw fish increases with time because it is tasty, light, and bouncy. In this paper, the growth characteristics dependent on the LED wavelengths and the optimal growth conditions of the starry flounder were studied. In these experiments 4 different kinds of LED lighting, configurations were designed and prepared using red, green, blue and white, respectively. The fish aquaculture experiments were conducted over 10 weeks in four fish tanks, each installed with a different color of LED lighting. 10 starry flounders of 13 ~ 17g were placed into each tank. The effects of each color of light on the growth rate of the starry flounders were then examined. As a result, the starry flounders under the green LED lighting showed the highest growth rate, followed by the white, red, and blue LED lighting. Based on these results, a green light provides a suitable breeding environment for the starry flounder.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.506-512
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• 2013

Recently, the color separation issue of wide-spreading white LEDs has attracted attention due to their wide applicability as light sources in direct-lit LCD backlights. These wide-spreading LED packages usually consist of LED chips, a color-conversion phosphor layer, and a light-shaping lens. The technical aspect of this color issue was related to a method for balancing the yellow spectral component emitting from phosphors with respect to the blue one from the LED chip as a function of viewing angle. In this study, we suggested an approach for carrying out quantitative analysis for the color separation problem occurring in wide-spreading LED packages by optical simulation. In addition, the effect of an internal scattering layer on the color uniformity was investigated, which may be considered as a potential solution for this problem.

• Environmental Engineering Research
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• v.23 no.2
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• pp.205-209
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• 2018

The spectral composition of light can affect the growth and biochemical composition of photosynthetic microalgae. This study examined the use of light filtering through a solution of soluble colored additives, a cost-effective method to alter the light spectrum, on the growth and lipid production of an oleaginous microalga, Nannochloropsis gaditana (N. gaditana). Cells were photoautotrophically cultivated under a white light emitting diode (LED) alone (control) or under a white LED that passed through a solution of red and yellow color additive (4:1 ratio) that blocked light below 600 nm. The specific growth rate was significantly greater under filtered light than white light ($0.2672d^{-1}$ vs. $0.1930d^{-1}$). Growth under filtered light also increased the fatty acid methyl ester (FAME) yield by 22.4% and FAME productivity by 80.0%, relative to the white light control. In addition, the content of saturated fatty acids was greater under filtered light, so the biodiesel products had better stability. These results show that passing white light through an inexpensive color filter can simultaneously enhance cellular growth and lipid productivity of N. gaditana. This approach of optimizing the light spectrum may be applicable to other species of microalgae.

• Journal of Bio-Environment Control
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• v.22 no.1
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• pp.49-54
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• 2013

In this study, I was focusing on LED (Light Emitting Diode) light effect in growth of chrysanthemum. For this reason, I formed six monochromatic lights (red 650 nm, 647 nm, 622 nm, blue 463 nm, 450 nm, white), six mixed lights sources red : blue (9 : 1, 8 : 2, 7 : 3, 6 : 4, 5 : 5) and 3 control beds in light sources ratio between rad : blue (8 : 2) including sun light. It was totally 15 control beds. Depending on light investigation time in growth, 6/6 (on/off) was highest in the length of plant, the number of leaves, the fresh dry and leaf area. But statistical significance wasn't accepted in general. In case of monochromatic lights, length of plant and leaf area is biggest in the Blue 450 mm and the length of root is highest in RED 650 mm. Except for this 3 measuring points (length of plant, the number of leaves and fresh weight), sun light and white was highest. Besides there are monochromatic light effect but various wavelength range in light sources are needed to crop growth. In terms of mixed light resources, except for sun light, It turned out the length of plant is highest in the highest red light rate red : blue (9 : 1), and Red : white (7 : 3) is highest in fresh weight and dry weight. The sun light is the highest one in the leaf area. The results from LED light effect in growth of chrysanthemum are obviously effect on growth and building up the shape. We need to choose suitable light sources in the monochromatic lights and mixed lights for growing high quality of chrysanthemum or Supplemental Lighting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9B
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• pp.1117-1125
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• 2011

In this paper, as a study of the simple visible light communication(VLC) with LED light, the visible light communication system that are made up with the $3{\times}3$ white LED array for visible light transmission, various photodiodes for visible light reception, and a non-carrier NRZ-OOK modulation scheme is designed and implemented to have a 115.2 kbps data speed at 2.5 m distance between transmitter and receiver. For the performance analysis of the developed VLC system, the maximum distance between VLC transmitter and receiver on the conditions of various transmission speeds, the number of LED array, or the various kind of LED and photodiode is obtained, and various performances are analyzed by experiments.

• Journal of agriculture & life science
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• v.53 no.6
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• pp.13-21
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• 2019

The influences of light generated by LEDs on shoot growth and photosynthesis of Tea plant(Camellia sinensis L.) were evaluated. The growth characteristics were investigated after 45 days of culture under four different light qualities: fluorescent lamp, red LED, blue LED, red+blue+white LED. Shoot growth was promoted by red light, especially root length and area were further promoted under the red+blue+white LED. Also, T/R ratio and Chlorophyll content were highest in red+blue+white. Fluor Cam was used to measure the fluorescence images of the plants, inhibition of photochemical efficiency(Fv/Fm) were not changed in all treatment. However, non-photochemical quenching(NPQ) were found rapidly increasing in blue LED, these results were that blue LED were inhibit photosynthetic efficiency and must be considered for efficiently in vitro cultivation of the tea plant. The above results suggest that light qualities could be an important factor to foster in vitro growth of the species. Also, In order to produce healthy plants, it is effective to using light qualities of red+blue+white LED on in vitro culture of the tea plant. These results could be used to mass propagating shoot and produce of healthy seedling.

• Clean Technology
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• v.16 no.2
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• pp.88-94
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• 2010

The physiological roles of various wavelength of light emitting diode (LED) on ‘Hayward’ kiwifruit experiencing after-ripening were investigated. Various wavelengths from LED light source were irradiated on kiwifruits kept in plastic bags or under open air at $25^{\circ}C$. During two weeks of storage, firmness of Hayward kiwifruits was decreased by $25^{\circ}C$ treatment than by $4^{\circ}C$ treatment. In the $25^{\circ}C$ storage condition, the firmness of kiwifruits was decreased by the treatment of 380 nm UV and 470nm white LED light source. Sweetness of kiwifruits treated with 380 nm UV LED and dark condition at $25^{\circ}C$ increased higher than $15^{\circ}$Brix. The acidity of kiwifruits under open air was decreased 52% by incubating at $25^{\circ}C$ with 660 nm red LED treatment. The acidity of kiwifruits in plastic bags was decreased 52.6, 55.6, 52.8% by the treatment of 440 nm blue, 470 nm white and 660 nm red LED light source, respectively, compared to that of kiwifruits incubated in darkness at $25^{\circ}C$. Decreased acidity irradiated by 660 nm red LED light source can be applied for regulating periods of the kiwifruit after-ripening process. LED light sources emit very narrow wavelength with a power-saving mode, therefore, the usage of these LED light source for regulating the after-ripening process can be classified as a clean biotechnology producing safe and environment-friendly kiwifruits.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.143-149
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• 2019

This study was conducted to investigate the graft-taking and growth of grafted cucumber seedlings as affected by light quality and blink cycle of LED modules. Four light quality treatments, namely blue, red, blue+red, white LED and four blink cycle levels of 5s/5s, 7s/3s, 9s/1s and control were provided to investigate the effect of lighting quality and blink cycle on the graft-taking and growth of grafted cucumber seedlings. Photoperiod for the control was 12/12 h. Photosynthetic photon flux, air temperature, and relative humidity for healing were maintained at $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $25^{\circ}C$, and 90%, respectively. There was no significant difference in graft-taking of grafted cucumber seedlings according to light quality except the blue LED with the blink cycle of 5s/5s. Regardless of the blink cycle, there was no significant difference in graft-taking of cucumber seedlings healed under red, blue+red, and white LED modules. These results implied that the effects of light quality and blink cycle on the graft-taking were not significant. Differences in the leaf length, leaf area, and fresh weight of cucumber seedlings healed blue or red LED with the blink cycle of 9s/1s were found to be significant. There was no significant effect of the blink cycle on the growth of cucumber seedlings healed under white LED modules. The prices of white LED are gradually falling due to increased demand. Considering the manufacturing unit price of white LED modules, the cost savings of 10-15% are expected as compared to the conventional blue/red LED modules. Therefore, it was concluded that the use of white LED modules will be economical as an artificial lighting sources for healing of grafted seedlings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.333-338
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• 2021

This study determined the characteristics of LED illumination and photosynthetically active radiation flux density (PPFD) for LED lighting design in an indoor plant factory. This was done based on the light wavelength and PPFD intensity required for plant growth. It has been found that the wavelength and intensity are decreased according to the measuring distance, and green light has an important role in illumination characteristics, while blue light has an important role in the PPFD characteristics. Considering only the photosynthetic properties of plants, the effective order of photosynthesis was blue>red>white>green. When the measurement distance was 30 [cm], it was found that reduction levels of 60 [cm], 90 [cm], and 120 [cm] decreased to about 36 [%], 18 [%], and 10 [%], respectively. As a result of the characteristics of mixed light (red:blue=2:1, 3:1, 4:1) and the measurement distance, when the measured value at 30 [cm] is 100%, the measured value at 120 [cm] is 10-11 [%]. From the obtained results, an optimal structure was proposed for maximizing the light efficiency of an indoor greenhouse for future research.

• Journal of Mushroom
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• v.12 no.4
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• pp.375-378
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• 2014

The attractions of Lycoriella ingenua to different LED light sources were investigated in the mushroom cultivations which were located in Yongin of Gyeonggi-do province and Buyeo of Chungcheongnam-do Province. The LED light sources which were used in the investigations were white, green, red, blue and orange. Numbers of Lycoriella ingenua to LED lights in Yongin and Buyeo were 132.9 and 3,272.5 to white LED source, 120.3 and 3,109.5 to green LED source, 105.5 and 1,910.1 to red LED source, 88.3 and 2,708.3 to blue LED source and 46.7 and 2,465.5 to orange LED source, respectively. The numbers of Lycoriella ingenua to LED light sources were 2.7~3.5 times higher than the ones of untreated.