• Journal of Bio-Environment Control
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• v.29 no.1
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• pp.1-8
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• 2020

The influence of growth regulators (NAA and BA) and sucrose concentrations (0, 3, 5, 7, 9%) on in vitro rapid-propagation of virus-free sweet potato [Ipomoea batatas (L.) Lam.] was investigated with single-node or shoot-tip culture of two cultivars ('Matnami' and 'Shinhwangmi'). The survival rate and growth of shoot-tip explant was also investigated under the presence or absence of light (blue and red LED = 7:3, 150±5 μmol·m^-2·s^-1 PPFD) during minimal-growth in vitro conservation at 15℃. Vine length, vine diameter, fresh weight and dry weight were enhanced without callusing of explant in the MS medium supplemented with 0.2-0.5 mg·L^-1 BA. The growth of single-node and shoot-tip explants were significantly enhanced with the increase of vine length, number of leaf, number of root, fresh weight, and dry weight in the solid medium containing 5% sucrose and 0.2 mg·L^-1 BA. Vine elongation of shoot-tip explants were highest in the liquid medium containing 3% sucrose than the solid medium. The survival rate of minimal-growth in vitro conservation was 100% in 5 months under the presence of light (LED, 150±5 μmol·m^-2·s^-1 PPFD) at 15℃, but the explants in dark condition died in 3 months. The light was absolutely necessary for the in vitro conservation under minimal-growth conditions of virus-free sweet potato plantlets at 15℃, and the high density of explants (10 plantlets per Petri Dish) was increased the efficiency of mass conservation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.45-50
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• 2016

This paper reports a Ringer's solution detector and transceiver design for the efficient management of patients. The ringer's solution detection and transceiver consisted of the main control part, ringer's solution detection part, display and warning light part, wireless transceiver, and power supply part. The light receiving part of the ringer's solution detection part employed TSL260R-LF photodiode; light permeating part, Water-Clear type LED; and wireless transceiver part, the RF wireless data transceiver module, NR-FPCX. As a result of this Ringer's solution detector and transceiver design that can manage the patient efficiently, it was found that when the ringer's solution was detected by the double photodiode, the operating frequency was 11.95kHz; when it was not detected, the number was 9.6kHz. In the ringer's solution receiver, when the ringer's solution was detected, the number was 0. The corresponding unique RF code was displayed when not detected. The power used in the ringer's solution detection part was converted to the Sleep mode to operate under battery save mode. The ringer's solution transceiver can exchange wireless communication approximately within a 700m radius.

• Journal of Applied Biological Chemistry
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• v.64 no.3
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• pp.197-203
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• 2021

Saponarin is a crucial component of barley sprout, and the production and quantitative analysis are issued to date. In this study, the optimal saponarin extraction conditions were presented on the subject of acetonitrile, ethanol, methanol, and water for the quantitative analysis in barley sprout through the extraction efficiency compared with the solvent concentration and extraction time using the reaction surface methodology. The optimal extraction time and solvent condition for saponarin were 3.9 h and 53.7% of aqueous methanol, respectively. In addition, the effect of LED artificial light on the saponarin production in barley sprouts was evaluated by the light cycle, light quantity, and light quality. The optimal cultivation conditions under artificial light for the growth of barley sprout and saponarin production were most effectively achieved on 220-320 μmol m^-2 s^-1 of the light quantity with 8 h day^-1 of a daylight cycle under 6500K LED combined with red light. Furthermore, blue light was evaluated as the main factor in the biosynthesis of saponarin.

• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.220-229
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• 2021

The optical characteristics of high-power direct-lit white light-emitting diode (LED) lighting were investigated, where a quantum dot (QD) film was adopted to enhance the color-rendering index (CRI). The transmittance of the diffuser plate and the concentration of the QD film were varied in this study. The color coordinates and the correlated color temperature (CCT) did not show any appreciable change, while the CRI values increased slightly as the transmittance of the diffuser plate decreased. The investigated optical properties were nearly independent of the viewing angle, and the luminance distribution was close to Lambertian. The CCT decreased from approximately 6000 K to approximately 4000 K as the concentration of the QD film increased from 0 to 7.5 wt%, which was due to the enhanced red component in the emission spectrum. The CRI increased to approximately 95 for some optical configurations of the lighting. These results demonstrate that glare-free, color-changeable, high-rendering LED lighting can be realized by using a combination of a diffuser plate of appropriate transmittance and a red QD film.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.319-325
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• 2015

Submicron-sized $CeO_2:Er^{3+}/Yb^{3+}$ upconversion phosphor particles were synthesized by spray pyrolysis, and their luminescent properties were characterized by changing the concentration of $Er^{3+}$ and $Yb^{3+}$. $CeO_2:Er^{3+}/Yb^{3+}$ showed an intense green and red emission due to the $^4S_{3/2}$ or $^2H_{11/2}{\rightarrow}^4I_{15/2}$ and $^4F_{9/2}{\rightarrow}^4I_{15/2}$ transition of $Er^{3+}$ ions, respectively. In terms of the emission intensity, the optimal concentrations of Er and Yb were 1.0 % and 2.0%, respectively, and the concentration quenching was found to occur via the dipole-dipole interaction. Upconversion mechanism was discussed by using the dependency of emission intensities on pumping powers and considering the dominant depletion processes of intermediate energy levels for the red and green emission with changing the $Er^{3+}$ concentration. An energy transfer from $Yb^{3+}$ to $Er^{3+}$ in $CeO_2$ host was mainly involved in ground-state absorption (GSA), and non-radiative relaxation from $^4I_{11/2}$ to $^4I_{13/2}$ of $Er^{3+}$ was accelerated by the $Yb^{3+}$ co-doping. As a result, the $Yb^{3+}$ co-doping led to greatly enhance the upconversion intensity with increasing ratios of the red to green emission. Finally, it is revealed that the upconversion emission is achieved by two photon processes in which the linear decay dominates the depletion of intermediate energy levels for green and red emissions for $CeO_2:Er^{3+}/Yb^{3+}$ phosphor.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.225-236
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• 2019

BACKGROUND: Hydroponics is one of the methods for evaluating plant production using the inorganic nutrient solutions, which is applied under the artificial light conditions of plant factory system. However, the application of the conventional inorganic nutrients for hydroponics caused several environmental problems: waste from culture mediums and high nitrate concentration in plants. Organic nutrients are generally irrigated as a supplementary fertilizer for plant growth promotion under field or greenhouse conditions. Hydroponic culture using organic nutrients derived from the agricultural by-products such as dumped stems, leaves or immature fruits is rarely considered in plant factory system. Effect of organic or conventional inorganic nutrient solutions on the growth and nutrient absorption pattern of green and red leaf lettuces was investigated in this experiment under fluorescent lamps (FL) and mixture Light-Emitting Diodes (LEDs). METHODS AND RESULTS: Single solution of tomatoes (TJ) and kales (K) deriving from agricultural by-products including leaves or stems and its mixed solution (mixture ration 1:1) with conventional inorganic Yamazaki (Y) were supplied for hydroponics under the plant factory system. The Yamazaki solution was considered as a control. 'Jeockchima' and 'Cheongchima' lettuce seedlings (Lactuca sativa L.) were used as plant materials. The seedlings which developed 2~3 true leaves were grown under the light qualities of FL and mixed LED lights of blue plus red plus white of 1:2:1 mixture in energy ratio for 35 days. Light intensity of the light sources was controlled at 180 μmol/㎡/s on the culture bed. The single and mixture nutrient solutions of organic and/or inorganic components which controlled at 1.5 dS/m EC and 5.8 pH were regularly irrigated by the deep flow technique (DFT) system on the culture gutters. Number of unfolded leaves of the seedlings grown under the single or mixed nutrient solutions were significantly increased compared to the conventional Y treatment. Leaf extension of 'Jeockchima' under the mixture LED radiation condition was not affected by Y and YK or YTJ mixture treatments. SPAD value in 'Jeockchima' leaves exposed by FL under the YK mixture medium was approximately 45 % higher than under conventional Y treatment. Otherwise, the maximum SPAD value in the leaves of 'Cheongchima' seedlings was shown in YK treatment under the mixture LED lights. NO₃-N contents in Y treatment treated with inorganic nutrient at the end of the experiment were up to 75% declined rather than increased over 60 % in the K and TJ organic treatment. CONCLUSION: Growth of the seedlings was affected by the mixture treatments of the organic and inorganic solutions, although similar or lower dry weight was recorded than in the inorganic treatment Y under the plant factory system. Treatment Y containing the highest NO₃-N content among the considered nutrients influenced growth increment of the seedlings comparing to the other nutrients. However effect of the higher NO₃-N content in the seedling growth was different according to the light qualities considered in the experiment as shown in leaf expansion, pigmentation or dry weight promotion under the single or mixed nutrients.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.5
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• pp.709-715
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• 2015

As consumers interest in microgreens is increasing worldwide, the production of leafy microgreens uisng different LED lights was investigated in this study. The experiment was carried out to evaluate the effects of different LED lights on the composition and vitamin C contents of buckwheat microgreens. Physicochemical properties of buckwheat microgreens grown under different lights (red, blue, and white) and control exposed to a dark room were investigated. Moisture contents of buckwheat microgreens were 95.65% under white light (WL), 95.75% under blue light (BL), 90.77% under red light (RL), and 89.71% under dark room (DR). Crude ash contents of buckwheat microgreens grown under WL, DR, RL, and BL were 0.39%, 0.39%, 0.31%, and 0.37%, respectively. Crude protein contents of buckwheat microgreens grown under DR, RL, WL, and BL were 7.12%, 7.81%, 1.60%, and 2.40%, respectively. Crude fat contents of buckwheat microgreens grown under DR, BL, RL, and WL were 1.12%, 0.54%, 0.35%, and 0.22%, respectively. $^{\circ}Brix$ was the highest in microgreens grown under BL and RL and the lowest in buds grown under DR. Vitamin C content was the highest in buds grown under WL and the lowest in buds grown under BL. Total chlorophyll content was the highest in microgreens grown under RL and the lowest in buds grown under WL. For mineral content measurement of buckwheat microgreens, Ca, K, Mg, and P contents were high whereas B, Cu, and Zn contents were not detected. The mineral contents of buckwheat microgreens according to each color of light showed significant differences. These results demonstrated that treatment of different colored LED lights during cultivation was able to increase vitamin C content up to affecting the nutritional value of buckwheat microgreens.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.297-300
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• 2017

Plant factory can control artificially the environments for crop cultivation, so they can produce high quality agricultural products all year round. This study was carried to select suitable kohlrabi cultivar for hydroponics in a closed-type plant factory system. We used three cultivars of red kohlrabi, 'Asac kohl', 'Kolibri', and 'Purple king' as plant materials. The artificial light source was LED light, light intensity and photoperiod were $249{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and 12/12 hours (day/night period), respectively. Hydroponic cultivation type was used circulating deep flow technique. At 43 days after transplanting, fresh weight of whole plant and tuber and leaf area were not significantly different among cultivars. Shoot dry weight and tuber dry weight were highest in 'Asac kohl' cultivar, and number of leaves was highest in 'Purple king' cultivar. Sugar content and yield were highest in 'Asac kohl' cultivar. Considering the growth and marketable yields, 'Asac kohl' was the optimal kohlrabi cultivar for hydroponic cultivation in a closed-type plant factory system.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.125-125
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• 2010

극성 [0001] 방향으로 성장된 질화물 기반의 LED (light emitting diode) 는 분극현상에 의해 발생하는 강한 내부 전기장의 영향을 받게 된다. 이러한 내부 전기장은 양자우물 내의 전자와 정공의 공간적 분리를 야기하고 quantum confined Stark effect (QCSE)에 의한 발광 파장의 적색 편이가 발생하며 양자효율의 저하를 가져오게 된다. 이러한 문제를 해결하기 위해 InGaN/GaN이나 AlGaN/GaN 양자 우물구조를 GaN의 m-plane (1$\bar{1}$00) 이나 a-plane (11$\bar{2}$0) 등 비극성면 위에 성장하려는 시도를 하고 있다. 그러나 비극성 면의 비등방성 (anisotropy) 으로 인하여 결정성이 높은 비극성 GaN을 성장하는 데에는 많은 어려움이 있다. GaN 층의 표면을 평탄화하고 결정성을 향상시키기 위해서 저온 GaN 또는 AlN 버퍼층을 성장하는 2단계 방법이나 고온 버퍼층을 이용하여 성장하는 연구들이 많이 진행되고 있다. 본 연구에서는 고온 GaN 버퍼층을 이용하여 기존의 2단계 성장과정을 단순화한 비극성 a-plane GaN을 r-plane 사파이어 기판위에 유기금속 화학증착법 (MOCVD)으로 성장하였다. 사파이어 기판위에 AlN 층을 형성하기 위한 nitridation 과정 후 1030 도에서 두께 45 ~ 800 nm의 고온 GaN 버퍼층을 성장하고 총 박막 두께가 2.7 ~ 3 um 가 되도록 a-plane GaN을 성장하여 표면 양상의 변화와 결정성을 확인하였다. 또한 a-plane GaN 박막 성장 시에 성장 압력을 100 ~ 300 torr 로 조절하며 박막 성장의 변화 양상을 관찰하였다. 고온 GaN 버퍼층 성장 두께가 감소함에 따라 결정성은 증가하였으나 표면의 삼각형 형태의 pit 밀도가 증가함을 확인하였다. 또한 성장 압력이 감소함에 따라 표면 pit은 감소하였으나 결정성도 감소하는 것을 확인하였다. 성장 압력과 버퍼층 성장 두께를 조절하여 표면에 삼각형 형태의 pit이 존재하지 않는 RMS roughness 0.99 nm, 관통전위밀도 $1.78\;{\times}\;10^{10}/cm^2$, XRD 반가폭이 [0001], [1$\bar{1}$00] 방향으로 각 798, 1909 arcsec 인 a-plane GaN을 성장하였다. 이 연구를 통해 고온 GaN 버퍼 성장방법을 이용하여 간소화된 공정으로 LED 소자 제작에 사용할 수 있는 결정성 높은 a-plane GaN을 성장할 수 있는 가능성을 확인하였다.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1308-1314
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• 2018

$Er^{3+}$ and $Yb^{3+}$ co-doped $Y_3Ga_5O_{12}$ polycrystalline powders were prepared by using a solid-state reaction method, and their crystallinities were measured using X-ray diffraction. According to the results of X-ray diffraction, the powders showed a polycrystalline tetragonal structure. The photoluminescence and the upconversion luminescence properties of the $(Y_{0.85-x}Yb_{0.15})_3Ga_5O_{12}:Er^{3+}_x$ (x = 0.03, 0.06, 0.09, 0.12 and 0.15) phosphors were investigated in detail. Green and red upconversion emissions were observed for the phosphors excited by 980 nm radiation from a semiconductor laser. The powders exhibited strong green and weak red upconversion emission peaks at 553 and 660 nm, respectively. Also, their upconversion processes were explained using an energy-diagram analysis and the strongest upconversion intensity was emitted by the powder with a 0.12 mol $Er^{3+}$ ion concentration.