• Journal of Mushroom
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• v.11 no.4
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• pp.226-229
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• 2013

This study was carried out to elucidate suitable wavelength of light during development of fruit body in Lentinula edodes. The four colors of LED(Light Emitting Diode), blue, green, red and yellow, were irradiated for formation of fruit-body. The effect of color of LED at all growth stage, the lightness of cap showed darker in blue and green LED irradiation than that of red and yellow LED. The longer stipe were resulted in longer wavelength. And the activity of anti-oxidant did not showed big differences according to LED wavelength. We obtained higher commercial yields and lower ratio of abnormal fruit body in green LED than those in control(fluorescent lamp).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.458-463
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• 2003

In order to develope piezoelectric transformer for the ballast of fluorescent lamp, a new shape and electrode pattern of piezoelectric transformer has been investigated in this work. The composition of piezoelectric ceramics was 0.95Pb(Zr$_{0.51}$Ti$_{0.49}$)O$_3$+0.03Pb(Mn$_{1}$3/Nb$_{2}$3/)O$_3$+0.02Pb(Sb$_{1}$2/Nb$_{1}$2/)O$_3$. The sample prepared by this composition system showed the characteristics which has about 1200 of relative dielecric constant, 1100 of the mechanical quality factor, 0.53 of the electromechanical coupling coefficient, 320 pC/N of the piezoelectric constant d$_{33}$, 0.3 % of the dissipation factor. Diameter and thickness of disk-type piezoelectric transformer was 45 mm and 4 mm, respectively. The driving and generating electrode with their gap of 1mm were fabricated on the top surface. But the common electrode was fabricated on the whole bottom surface. The electrode surface ratio of driving and generating part on the top surface ranges from 1.4:1 to 3:1. We investigated the electrical characteristics with the variation of the electrode surface ratio of driving and generating part in the range of load resistance of 100 $\Omega$～70 k$\Omega$. The set-up voltage ratio of this piezoelectric transformer increases with increasing both the electrode surface of driving part and the load resistance. The set-up voltage ratio at no load resistance was more than 60 times. On the other hand, the efficiency decreases with increasing the electrode surface of driving part. In the case of the electrode surface of both 1.4:1 and 2:1, maximum efficiency showed above 97 % at load resistance of 2 k$\Omega$. However, in the case of the electrode surface of 3:1, maximum efficiency showed about 94 % at load resistance of 3 k$\Omega$.>.>.>.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.89-95
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• 2013

A DBLP(Double blind light pipe) daylight system can be installed at a building exterior wall or roof to replace artificial light during the day time. This system was consisted of a double blind light collector, a mirror duct type light transformer and a prism light pipe distributor. The double blinds were used to track the sun's altitude and azimuth movements to collect the sunlight throughout the day. The sunlight collected by the light collector was reflected on the first mirror and the second mirror and sent to the light pipe through the light transformer. The transformer was designed to deliver the sunlight into the light pipe efficiently. The light distributor plays a role in diffusing the sunlight coming in through the light collector to be used for indoor lighting. In this paper, a DBLP system has been designed, installed and tested at a KIER daylighting twin test cell. The DBLP daylighting system was applied to the experimental test cell which has an indoor area of 2.0 m wide ${\times}$ 2.4 m height ${\times}$ 3.8 m length. The experiment was conducted from January 30 to February 27, 2012, under clear skies and partially cloudy skies. Data was collected from 10:00 am to 16:00 pm every 2 minute and the average was calculated for every 30 minute of the data collection to obtain the system efficiency. The results indicated that the DBLP system efficiency was evaluated as 11.67%. The DBLP system indoor illumination energy reduction was predicted as 0.822 kWh/day. This could replace 4 sets of a 32W fluorescent lamp operating 6.4 hours per a day.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.4
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• pp.326-331
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• 2010

This paper has proposed and experimentally demonstrated a new BLU using an LED and an acryl, which is specially focused on the implementation about the guiding effect of an acryl luminous by the LED. While the conventional BLU using a fluorescent lamp is generally and widely used, it shows big power consumption with a short life even more too thick to hold on the wall. To solve such demerits, we propose a new method for a BLU using an LED and an acryl in this paper. This BLU system has various scratches on the surface of acryl to get diffusion effect of light, and has been included an embedded board that can dynamically control the colors and the intensity of the BLU through the Internet. We have conducted computer simulations to find out the optimal scratch pattern on the surface of the acryl for the backlight system. Based on the resulted out simulation. The the optimal scratch pattern signs has been developed. The simulation result shows 2,673Lux an average for a luminous intensity test, and the other hand, experiential result shows 2,554Lux. From the experiments, it is possible for the proposed BLU system to be used for real advertisements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.441-443
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• 2005

According as CCFL(Cold Cathode Fluorescent lamp) of light source in Backlight unit for Note PC (Personal computer) is presently needed to low power consumption and long life time, the development focus of CCFL is going on the discharge gas, phosphor and electrode material. First of all, discharge voltage characteristic of CCFL is closely connected with electrode material For low discharge voltage, the characteristic of electrode material is needed to low work function, low sputtering ratio and superior manufacturing property. We developed new CCFL with Nb/Ni Clad electrode superior to conventional CCFL. Because Nb/Ni Clad electrode with Ni material and Nb material, the electrical characteristic is superior to other electrode materials. The electrode of Nb/Ni Clad is composed that Ni of outside material has superior manufacturing property and Nb of inside material has low work function. Nb/Ni Clad of new electrode material is made by process of Rolling mill at high pressure and heat treatment. We compared electrical characteristic of Nb/Ni clad electrode with conventional Mo electrode by measurement. Mo electrode and Nb/Ni Clad electrode of cup type with diameter 1.1 mm and length 3.0mm are used to this experiment. Material content of Mo electrode is Mo 100%. But, Nb/Ni Clad electrode is composed by content of Nb 40% and Ni 60%. The result of comparison measurement between new CCFL with Nb/Ni Clad electrode and conventional CCFL was appeared that CCFL with Nb/Ni Clad electrode had superior characteristic than conventional CCFL. As a result of experiment, we completed Note PC with low power consumption and long life time by application of new CCFL with Nb/Ni Clad electrode.

• Journal of Plant Biotechnology
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• v.35 no.3
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• pp.215-221
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• 2008

Effects of light generated by LEDs on shoot growth and rooting of Tsuru-rindo(Tripterospermum japonicum) were evaluated. Apical shoots(one or two node with 3-4 leaves) were cultured on MS basal medium with 3% sucrose and maintained for four weeks under five different light qualities: fluorescent lamp(F), 100% red LED(R), 70% red LED+30% blue LED(R7B3), 50% red LED+50% blue(R5B5), or 100% blue LED(B). Rooting was promoted by both red light and fluorescent lamp, and the effect was further promoted under the ventilation. Red light enhanced shoot node elongation, whereas blue light appeared to suppress it. Growth of shoots and leaves were enhanced under the ventilation irrespective of the different light qualities. Under the ventilated condition, total fresh weight of plants was highest in R7B3 LED as 257.7 mg per plant. Dry matters, which are used for index of plant growth, were lowest under red light, whereas it was highest under blue light. The dry matter was inclined to getting higher by ascending the ratio of blue light and red light. Total chlorophyll content was highest in both R7B3 LED and R5B5 LED under ventilation as 29.5 and 31.2, respectively. Above results suggest that light quality optimization could be an important factor to foster in vitro growth of the species. Ventilation treatment appeared to be another important factor to induce normal shoot growth and rooting.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.358-363
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• 2014

BACKGROUND: Many strawberry growers are utilizing daylength extension by using incandescent bulb or fluorescent lamp to break dormancy of strawberry induced by low temperature and short day conditions. Conventional incandescent bulb and fluorescent lamp consume a lot of electricity and have short longevity. Red light known for most efficient wavelength for daylength extension light of short-day plant and long-day plant. This study was conducted to verify the effects of red light to enhance growth and to increase production of strawberry (Fragaria ${\times}$ ananassa Duch. cvs. "Seolhyang") METHODS AND RESULTS: Three red light (660nm) of 0.70, 0.87, and $1.05{\mu}mol/m^2/s$ (PAR) and conventional incandescent bulb of 40 Lux were treated respectively under the pot experiment. All treatment irradiated from 18:00 to 24:00 for 6 hours. Red light treatment tend to increase leaf stem number, flower stem number, weight of flower stem, crown weight, root weight, and leaf area of strawberry then incandescent bulb treatment. In field experiment, red light of $0.7{\mu}mol/m^2/s$ (PAR) and conventional incandescent bulb of 40 Lux were irradiated respectively. Field experiment showed that the leaf number, leaf weight, and crown weight of strawberry increased than those of incandescent bulb control with red LED of $0.7{\mu}mol/m^2/s$ (PAR). Red LED treatment increased the fruit number over 15g than incandescent bulb. Furthermore, red LED treatment decreased fruit number below 15g of strawberry than incandescent bulb treatment. Therefore, We believed that red LED treatment increased marketable fruit number by increment of weight of each fruit. Consequently, marketable fruit number, fruit weight, and fruit production of strawberry were increased than those of incandescent bulb by 5 %, 2.9 %, and 8.5 % respectively, but not showed significantly differences. CONCLUSION: These results presumably due to directly enhanced photosynthesis of strawberry leaves and activated action of Pfr phytochrome form by red light. In conclusion, red LED of 660nm could be used for daylength extension light source to enhance production of strawberry.

• Journal of Korean Society of Forest Science
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• v.27 no.1
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• pp.15-21
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• 1975

According to Yoshihisa Kuroki's report that the total amount of carotenoid was more in the susceptible to pine bark beetle, than in the resistant ones, carotenoids were extracted from needle leaves of one year old seedlings of Pinus thunbergii, Pinus desiflora, Pinus rigida, Pinus koraiensis, Pinus rigitaeda and Pinus taeda which are all important pines in Korea, to find their resistant ratio to the insect. The carotenoids were analyzed and compared using the spectra of them by spectrophotometer. The results were as follows: 1. The visible absorption spectra of carotenoids in those pine trees were proved to be very similar. 2. The total amount of carotenoids in needles differed with the tree species and the contents were arranged in decreasing order P. koraiensis>P. rigida>P. thunbergii>P. rigitaeda>P. taeda, it seemed that there was corelation between the cartenoid content and the extent of harm caused by the pine bark beetles except P. koraiensis. 3. But carotenoids were contained in Robinia pseudoacacia, Castanea crenata, Chamaecyparis obtusa and Cedrus deodra leaves too. 4. The total amounts of carotenoids in these pines of 9 species were arranged in decreasing order Robinia pseudoacacia>Pinus koraiensis>Pinus rigida>Pinus thunbergii>Castanea crenata>Pinus rigitaeda>Pinus taeda>Chamaecyparis obtusa>Cedrus deodara. Therefore, it was proved that there was no correlation between carotenoid cotent and extent of resistance to the insect. 5. In the thin-layer chromatography of these carotenoids, 13 kinds of components in P. densiftora, P. koraiensis and P. rigida and 12 kinds of spots in other pines, were detected respectively, under ultra-violet fluorescent lamp $3,600{\AA}$ and $2,537{\AA}$. 6. The eighth spots from the bottom in P. densiflora, P. koraiensis and P. rigida were not found in other pines and other 4 species (Robinia pseudoacacia, Castanea crenata, Chamacyparis obtusa, Cedrus deodra). Especially the spot in P. densiflora fluoresced strong cobalt blue-fluorescence under ultra-violet fluorescent lamp $2,537{\AA}$.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.342-352
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• 2023

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20℃ temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 µmol m^-2 s^-1. The kale plants were then transferred to two chambers with different CO₂ concentrations (382±3.2 and 1,027±11.7 µmol mol^-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m^-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO₂ were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO₂ environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO₂ environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

• Horticultural Science & Technology
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• v.35 no.4
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• pp.490-498
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• 2017

The in vitro growth of virus-free sweet potato [Ipomoea batatas (L.) Lam.] plantlets was investigated under different light sources: fluorescent lamp (control); red (660 nm), blue (460 nm), white light-emitting diodes (LED), and two mixtures of blue and red LED (R:B = 8:2, and 7:3). Single node explants (10 mm) of three cultivars ('Matnami', 'Shincheonmi', and 'Yeonhwangmi') were cultured on Murashige and Skoog medium supplemented with $0.2mg{\cdot}L^{-1}$ 6-benzyladenine for 4 weeks. Explants were exposed to $150{\pm}5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux at a distance of 20 cm, constant temperature of $25^{\circ}C$, and under 16/8-h (day/night) photoperiod. Using the same method, the in vitro growth of 10 cultivars under red LED was also compared. After 3 weeks, vine length was highest in plantlets cultured under red LED, and lowest in plantlets cultured under blue LED. Fresh and dry weights were also greatest in plantlets cultured under red LED. Compared to the control, vine thickness was significantly higher in plantlets grown under white LED and the 7:3 R:B LED mixture. Significant differences were observed among the 10 cultivars grown under red LED. 'Matnami', 'Shincheonmi', and 'Shinhwangmi' all had excellent vine lengths, and fresh and dry weights. Compared to the control, vine elongation of sweet potato plantlets was most effective under red LED, and culture duration was about 1 week shorter.