• Horticultural Science & Technology
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• v.35 no.2
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• pp.178-187
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• 2017

The aim of this study was to investigate the effect of different light sources on the levels of glucosinolates (GSLs) in rocket salad (Eruca sativa L.). The light sources used in the study were: natural light (Control-1 or 2), red light-emitting diodes(LEDs), blue LEDs, mixed red and blue LEDs (R+B LEDs), white LEDs, fluorescent lamps (FL), and fluorescent lamps plus UV-C (FL+UV-C). Two separate experiments were conducted [Experiment I: Control-1, Red LED, Blue LED, Mix (R+B) LED and Experiment II: Control-2, White LED, FL, FL+UV-C] because of the limited number of growth chambers in our laboratory. The rate of increase in the length of rocket salad leaves was the highest under red LEDs and, FL confirming that red LED and, FL affect the growth of rocket salad. We separated and identified seven types of GSLs from the rocket salad:glucoraphanin, diglucothiobeinin, glucoerucin, glucobrassicin, dimeric 4-mercaptobutyl GSL, 4-methoxyglucobrassicin, and gluconasturtiin. The highest total GSL contents in Eexperiment I was found in plants grown under in red LEDs ($4.30{\mu}mol{\cdot}g^{-1}\;dry$ weight, DW), and the lowest under blue LEDs ($0.17{\mu}mol{\cdot}g^{-1}\;DW$). The highest total GSL contents in Experiment II was found in plants grown under FL ($13.45{\mu}mol{\cdot}g^{-1}\;DW$), and the lowest in FL+UV-C ($0.39{\mu}mol{\cdot}g^{-1}\;DW$). Especially in Experiment II, the content of dimeric 4-mercaptobutyl, which has a strong aroma and spicy flavor in rocket salad, was higher under FL and white LEDs than in Control-2, increasing by approximately 14.9 and 3.2-fold respectively. Therefore, light sources such as red LEDs, white LEDs and FL affected the accumulation of GSLs in rocket salad.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.133-137
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• 2016

Use of UV gel for nail management have been increasing gradually. In order to develop an UV lamp necessary to UV gel, in this study, we was designed circuits of the UV-LED lamp. Power supply part that supplies constant power to the several UV-LEDs, was designed the circuit with the method of DC-DC converter. Taking into account the direction of the thumb nail and the position of the little finger nail, it was placed UV-LEDs. Input power of the power supply part was used as a battery voltage of 3.8[V]. The output voltage of the power supply part was appeared in approximately 3.1[V]. And in order to examine the state of change of the output voltage according to the amount of current consumption of UV-LEDs, after inserting of load resister, the output voltage was more than about 3.0[V] in the simulation results of the power supply part while changing the resistance value.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.959-964
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• 2009

This paper dealt with the disinfection performance by Ultra-Violet Light Emitting Diode (UV LED) for a phytoplankton as a basic study for the development of a low-energy consumption ballast water treatment system. UV LEDs having peak wavelength of 255nm, 265nm and 280nm were used in the experiment. UV LED modules with driving circuit were fabricated, and optical and electrical characteristics of them were analyzed. The disinfection performance for phytoplankton depending on the UV wavelength was evaluated by comparing the number of phytoplankton before and after the UV treatments. The experimental result showed that the highest disinfection wavelength for the phytoplankton was 265nm.

• ETRI Journal
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• v.35 no.4
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• pp.566-570
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• 2013

In this paper, we demonstrate the capabilities of 380-nm ultraviolet (UV) light-emitting diodes (LEDs) using metal organic chemical vapor deposition. The epi-structure of these LEDs consists of InGaN/AlGaN multiple quantum wells on a patterned sapphire substrate, and the devices are fabricated using a conventional LED process. The LEDs are packaged with a type of surface mount device with Al-metal. A UV LED can emit light at 383.3 nm, and its maximum output power is 118.4 mW at 350 mA.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.273-276
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• 2011

Ultraviolet (UV) light emitting diodes (LEDs) were grown on a patterned n-type GaN substrate (PNS) with 200 nm silicon-di-oxide (SiO2) nano pattern diameter to improve the light output efficiency of the diodes. Wet etched self assembled indium tin oxide (ITO) nano clusters serve as a dry etching mask for converting the SiO2 layer grown on the n-GaN template into SiO2 nano patterns by inductively coupled plasma etching. PNS is obtained by n-GaN regrowth on the SiO2 nano patterns and UV-LEDs were fabricated using PNS as a template. Two UV-LEDs, a reference LED without PNS and a 200 nm PNS UV-LEDs were fabricated. Scanning Electron microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Photoluminescence (PL) and Light output intensity- Input current- Voltage (L-I-V) characteristics were used to evaluate the ITO-$SiO_2$ nanopattern surface morphology, threading dislocation propagation, PNS crystalline property, PNS optical property and UVLED device performance respectively. The light out put intensity was enhanced by 1.6times@100mA for the LED grown on PNS compared to the reference LED with out PNS.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.174-174
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• 2005

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.339-345
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• 2018

We investigated the curing properties of cured coatings for a multi-focal UV-LED. The coatings are for LEDs that operate at multiple UV wavelengths, unlike conventional single-wavelength UV-LEDs. Using UV-LED light sources with wavelengths of 365, 395, 420, and 450 nm, we analyzed the optical characteristics such as the direction of light flux and light source. We also analyzed the curing characteristics at each UV-LED wavelength to optimize the LED for composite wavelengths. The curing performance state was predicted through computer simulation for when the multiple wavelengths of UV light sources are superimposed, and then actual LEDs were designed and fabricated. To improve the internal high-speed curing, a multi-spot module was fabricated, in which each LED is condensed, and multiple wavelengths are synthesized and condensed at the same position. The adhesive strength, surface hardness, and internal hardness of the curing agent were tested by varying the wavelength combination conditions. The surface hardening and internal hardening were compared and analyzed using a hardness tester and FT-IR analyzer. As a result, the characteristics of the surface and internal hardness were improved by a multi-spot method in which four wavelengths were overlapped in a UV-LED rather than a single wavelength.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.277-277
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• 2017

The research was carried out to investigate a total polyphenol content, antioxidant activity, amino acid and resveratrol content of peanut sprouts (cotyledon, epicotyl, leaf, hypocotyl, root), in different light (white, blue, red, F-red, UV-A, UV-B, UV-C) conditions for 24 hours. Peanut seeds were sown on a $27.5{\times}15.9{\times}13cm$ tray and grown at the $25^{\circ}C$ under the dark condition for 14 days. Total polyphenolic contents of epicotyl and leaf were about 288mg GAE/100g in blue light. The DPPH radical scavenging of cotyledon and hypocotyl were 1.3~1.5 times (63%) and 2 times (40%) compared to control (43%, 19%), respectively. As to ABTS activity, its activity was increased by all LEDs treatment, Especially, the highest ABTS activity of the hypocotyl and leaf was shown as 99.1% in blue light. The essential amino acid content of hypocotyl and leaf was increased 1.9 times in the UV-B, 1.6 times in red, and 1.5 times in F-red, respectively. The non-essential amino acid content was increased by all LEDs treatment in hypocotyl and leaf. The content of resveratrol was increased by 1.3 times in UV-B compared to that of other tissues. Assessing inclusively, this study showed that there was a significantly positive effect between increase of physiological substance activity and LED light treatment, resulting in stably producing peanut sprouts. Therefore, a material treated with LEDs is thought to be useful as a functional food resources.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.39-44
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• 2015

Optical characteristics including the radiant flux and viewing angle of UV LEDs were investigated according to both silicone encapsulants with different refractive indexes and lens shapes. Lead frame was fabricated using the enhanced heat dissipation characteristics with a heat slug structure and the reflector based on EMC(Epoxy Mold Compound) material. Four types of lens shapes were designed and their optical characteristics depending on the refractive index of silicone encapsulants were evaluated. The maximum radiant flux can be achieved when the height of lens are 1.32mm and 1.08mm for silicone encapsulants with low and high refractive indexes, respectively. Depending on the encapsulating method, the viewing angle changes from $148.9^{\circ}$ to $130.2^{\circ}$ for low refractive index and from $145.3^{\circ}$ to $136.8^{\circ}$ for high refractive index. As a result, it is found that the optical characteristics of UV LEDs can be controled through both encapsulating method and the refractive index of encapsulants.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.194-198
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• 2013

In this paper, we studied a p-type reflector based on indium tin oxide (ITO) for vertical-type ultraviolet light-emitting diodes (UV LEDs). We investigated the reflectance properties with different deposition methods. An ITO layer with a thickness of 50 nm was deposited by two different methods, sputtering and e-beam evaporation. From the measurement of the optical reflection, we obtained 70% reflectance at a wavelength of 382 nm by means of sputtering, while only 30% reflectance resulted when using the e-beam evaporation method. Also, the light output power of a $1mm{\times}1mm$ vertical chip created with the sputtering method recorded a twofold increase over a chip created with e-beam evaporation method. From the measurement of the root mean square (RMS), we obtained a RMS value 1.3 nm for the ITO layer using the sputtering method, while this value was 5.6 nm for the ITO layer when using the e-beam evaporation method. These decreases in the reflectance and light output power when using the e-beam evaporation method are thought to stem from the rough surface morphology of the ITO layer, which leads to diffused reflection and the absorption of light. However, the turn-on voltage and operation voltage of the two samples showed identical results of 2.42 V and 3.5 V, respectively. Given these results, we conclude that the two ITO layers created by different deposition methods showed no differences in the electric properties of the ohmic contact and series resistance.