• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.155-159
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• 2015

Light emitting devices (LEDs) are widely used in the liquid crystal display (LCD) industry, especially for LCD back light units. Therefore, much research has been performed to minimize manufacturing costs. However, the current process does not process LED chips from broken substrates even though the substrate is expensive sapphire wafer. This is because the broken substrates lose their alignment marks. After pre-processing, LED dies are glued onto blue tape to continue post-processing. If auxiliary alignment marks are stamped on the blue tape, post-processing can be performed using some of the LED dies from broken substrates. In this paper, a novel stamper module that can stamp the alignment mark on the blue tape is proposed, designed, and fabricated. In testing, the stamper was reliable even after a few hundred stamps. The module can position the stamp and apply the pattern effectively. By using this module, the LED industry can reduce manufacturing costs.

• Journal of Environmental Science International
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• v.27 no.10
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• pp.821-829
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• 2018

This study was conducted to examine the influence of Light-Emitting Diode (LED) light quality in urban agricultural plant factories on the growth and development of Seolhyang strawberry daughter plants in order to improve the efficiency of daughter plant growth and urban agriculture. LED light quality by demonstrated that above-ground growth and development were greatest for daughter plant 2. Daughter plant 1 showed the next highest growth and development, followed by daughter plant 3. Among the different qualities of LED light, the stem was thickest and growth rate of leaves was highest for R + B III (LED quality: red 660 nm + blue 450 nm/photosynthetic photon flux density (PPFD): $241-243{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and lowest for R (red $660nm/115-117{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). Plant height, leaf width, petiole length, and the leaf growth rate were highest for W (white fluorescent lamp/$241-243{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and lowest for R + B I (red 660nm+blue 450nm/$80-82{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). For above-ground growth and development, as the plants surpassed the seedling age, mixed light (red + blue), rather than monochromatic light (red or blue), and higher PPFD values tended to increase development. Regarding the quality of the LED light, daughter plant 2 showed the highest chlorophyll content, followed by daughter plant 1, and daughter plant 3 showed the least chlorophyll content. When the wavelength was monochromatic, chlorophyll content increased, compared to that when PPFD values were increased. Mixed light vitality was highest in daughter plant 2, followed by 1, and 3, showed increased photosynthesis when PPFD values were high with mixed light, in contrast to the results observed for chlorophyll content.

• Research in Plant Disease
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• v.22 no.2
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• pp.100-106
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• 2016

We have studied the mycelia growth of four soil-borne fungal pathogens under light qualities and two lighting types (continuous and intermittent) provided by light-emitting diodes (LEDs). As a result, each mycelia growth on Phytophthora cactorum KACC40166, Athelia rolfsii KACC40170, and Helicobasidium mompa KACC40836 strain showed the similar growth rates within 10% or less difference among treatments compared to dark control, regardless of lighting types. However, the mycelia growth on Rosellinia necatrix KACC40168 strain was significantly suppressed by blue, blue+green and blue+red LED as well as fluorescent lamp compared to a dark control, in common with lighting types. The melanin pigment on R. necatrix KACC40168 strain showed relatively to induce more strongly under green LED and fluorescent lamp, whereas no induction under red LED and a control, regardless of lighting types. Thus, the hypha width on R. necatrix KACC40168 was significantly thinned by blue and blue+green LED compared to a control, in common with lighting types.

• The Korean Journal of Mycology
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• v.51 no.2
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• pp.69-80
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• 2023

The cultivation conditions of shiitake mushrooms (Lentinula edodes) influence the production and quality of fruiting bodies. We conducted this study to improve the productivity and quality of shiitake mushrooms by modifying the cultivation conditions. Two types of spawns (sawdust and liquid spawn) were used, and corn flour was used as a nutritional source for the sawdust medium. A blue light-emitting diode (LED; 300 lux) was also used instead of a white LED during the incubation period. Sanbaekhyang was used as the experimental variety. When using corn flour, the mycelial growth rate increased 1.1 to 2.7 times the growth rate of the control up to 21 days of incubation, and the weight loss rate of the media was also higher. Mushroom productivity increased 1.2 times when the liquid spawn was used compared to when the sawdust spawn was used, and the blue LED also increased fruiting body production by 1.1 times compared to the white LED. Mushroom productivity increased when the liquid spawn was used, and the blue LED also increased fruiting body production. Fruiting body weight and the size of the cap were greater when sawdust spawn was used. The fruiting body weight and the stipe diameter were greater when the blue LED was used. Taste analysis showed that the saltiness increased when corn flour was used, and the sourness increased when the blue LED was used.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.8
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• pp.24-30
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• 1998

A blue LED of $In_{x}Ga_{1-x}N$ multiple quantum well structure which had the blue emission spectrum of donor-acceptor pair transition generated form Si-Zn co-doped $In_{x}Ga_{1-x}N$ active layer, was fabricated. The $In_{x}Ga_{1-x}N$ MQW heterojunction LED structure was grown by MOCVD on the sapphire substrate with (0001) surface orientation at 800.deg. C. The fabricated LED exhibited forward cut-in voltage of 4~4.5V and reverse breakdown voltage of -13V. Its optical chracteristics showed that the center wavelength of peak emission occurred at 460nm and the optical intensity was increased linearly with respect to the injected electrical current above 5mA.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.31-35
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• 2004

A blue light emitting diode with 8 periods InGaN/GaN multi-quantum well structure grown by metal-organic chemical vapor deposition was fabricated with the inclusion of the metal-interconnection process in order to integrate the chips for light lamp. The quantum well structure provides the blue light photoluminescence peaked at 479.2 nm at room temperature. As decreasing the temperature to 20 K, the main peak was shifted to 469.7 nm and a minor peak at 441.9 nm appeared indicating the quantum dot formation in quantum wells. The current-voltage measurement for the fabricated LED chips shows that the metal-interconnection provides good current path with ohmic resistance of 41 $\Omega$.

• Food Science and Preservation
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• v.19 no.5
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• pp.645-651
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• 2012

The food functional properties of Pleurotus eryngii cultivated with different wavelengths of light-emitting diode (LED) light were analyzed in this study. The levels of total soluble solids of Pleurotus eryngii increased with all the LED lights, except mixed LED light ($B^*R$, $B^*G$ and $R^*G$). Thirty one kinds of components were detected by analyzing the free amino acids. The total free amino acid contents had a slightly higher tendency in the control group, but the ratios of eight essential amino acids among the total amino acids of Pleurotus eryngii cultivated under all the LED lights, including the blue light (blue, $B^*R$, $B^*G$ and $B^*R^*G^*U$) and the green light, were higher than that in the control group. K was the highest-content of mineral, and Mn was the lowest-content. The Ca content increased through cultivation under all the LED lights, except the blue light, but the Fe content (under the green and $B^*R$ lights), K content (under the red and UV-A lights) and Mg content (under the $R^*G$, UV-A and red lights) increased under the exclusive LED light. The total phenolic compounds increased by cultivation under all the LED lights, except the UV-A and mixed lights ($R^*G$ and $B^*R^*G^*U$). The DPPH radical scavenging activity was also improved by all the LED lights, except the mixed light ($R^*G$).

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.32-40
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• 2014

This study was conducted to evaluate the growth response of economical six leafy vegetables that are crown daisy, pak-choi and four kinds of lettuce (Red leaf lettuce, Green leaf lettuce, Head lettuce, Romaine lettuce) by light treatment of LED in plant factory. The light treatments were composed of red, blue, red+farred, red+blue, red+blue+white LEDs, irradiation time ratio of the red and blue LED per minute (1 : 1, 2 : 1, 5 : 1, 10 : 1), and duty ratio of mixed light (100%, 99%, 97%). The following results were obtained in different LED light sources treatments: Shoot biomass and S/R ratio of romaine lettuce were the highest under mixed red+blue LEDs. S/R ratio of head lettuce was higher under mixed red+blue+white LEDs than red+blue LEDs. The others showed no difference in LED light treatment. Shoot biomass, total biomass and S/R ratio of green lettuce, head lettuce and pak-choi were highest in the higher red ratio (5 : 1) on irradiation time of red : blue LED ratios. By the different duty ratio (red+blue and red+blue+white LEDs), Under the mixed light of red+blue, shoot and root biomass of crown daisy and romaine lettuce were high in duty ratio of 100% and 99%, and S/R ratio was highest in all the 6 kinds in duty ratio of 97%. All the 6 kinds showed a fine growth state in low duty ratio (97%). Green lettuce, romaine lettuce and pak-choi showed relatively high shoot biomass and total biomass in low duty ratio of 97% under the mixed light of red+blue+white. S/R ratio of romaine lettuce and head lettuce were highest in the duty ratio of 97% with red+blue+white LEDs. Thus, we can cultivate stably without reference to external factors, if we use appropriate light sources and light quality in closed-type plant factory.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.431-435
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• 2009

This study was conducted to compare the effect of various LED and UVa light to enhanced coloration of paprika fruits cultivars; 'Special', 'Helsinki'. Immatured paprika fruits were irradiated with red LED, blue LED and UVa lights which were high intensity (red: $50{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, blue: $70{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, UVa: $3{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and low intensity (red: $20{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, blue: $40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, UVa: $0.25{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). The coloration of 'Special' cultivar was increased the fastest in high intensity UVa light for 2 days after treatment. There were no significantly difference among treatments except the low intensity UVa light. The coloration of 'Helsinki' was increased the fastest in blue LED light, and followed by red LED light and UVa light for 2 days after treatment. The $a^*/b^*$ value of 'Special' and $b^*$ value of 'Helsinki' that indicated the paprika fruit coloration were generally higher high intensity LED and UVa lights than low intensity LED and UVa lights. We couldn't find out any significantly different coloration effect among all treatments in final days of coloration. and rather than UVa treatment fruit shrunk the surface of paprika fruits.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.93-101
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• 2007

In order for bioremediate the benthic layer in polluted inner Bay, the effects of irradiance and wave-length irradiated from light emission diode (LED) on the growth of benthic diatom Nitzschia sp. (Hakozaki Bay strain of Japan) were investigated. The Nitzschia sp. was cultured under blue LED (450 nm), yellow LED (590 nm), red LED (650 nm) and fluorescent lamp (mixed wavelengths). At $25^{\circ}C$ and 30 psu, the growth of Nitzschia sp. showed its peak at $20\;{\mu}mol\;m^{-2}\;s^{-1}$ (blue LED) and $40\;{\mu}mol\;m^{-2}\;s^{-1}$ (fluorescent lamp), and was inhibited at the irradiance higher than that irradiance. Nitzschia sp. in yellow LED and red LED is fitted by a rectangular hyperbolic curve because no photoinhibition was observed under maximum irradiance used in this study. The irradiance-growth curves were described as ${\mu}=-0.46{\exp}(1-I/6.32)+0.46-0.00043I,\;(r^2=0.98)$ under blue LED, ${\mu}=0.42(I+7.87)/(I+58.9),\;(r^2=0.99)$ under yellow LED, ${\mu}=0.39(I+3.39)/(I+21.6),\;(r^2=0.94)$ under red LED, ${\mu}=-0.38{\exp}(1-I/7.23)+0.38-0.00016I,\;(r^2=0.96)$ under fluorescent lamp. Maximum specific growth rate of blue LED, yellow LED, red LED and fluorescent lamp was $0.44\;day^{-1},\;0.42\;day^{-1},\;0.39\;day^{-1}$ and $0.37\;day^{-1}$, respectively. The absorption coefficient ($a_{ph}$) of Nitzschia sp. was similar under all the wavelengths (400 nm-700 nm), although maximum $a_{ph}$ was $0.0224\;m^2\;mg\;chi.\;{\alpha}^{-1}$ in 472 nm and $0.0179\;m^2\;mg\;chi.\;{\alpha}^{-1}$) in 663 nm. The results may indicate the possibility of environmental improvement around the benthic layer in polluted coastal area because microphytobenthos growth is stimulated by means of irradiated blue LED at the benthic boundary layer during both autumn and winter, and yellow LED, which might have been suppressed growth of harmful algae, at the layer during both spring and summer.