• Journal of Applied Biological Chemistry
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• v.59 no.2
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• pp.95-98
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• 2016

Phototactic behavioral responses of the Indian meal moth, Plodia interpunctella ($H{\ddot{u}}bner$), adults were determined to different light-emitting diodes (LEDs) of seven wavelengths, and their behavioral responses were compared to that using a commercial luring lamp (BLB) under laboratory conditions. Based on the attractive responses under optimal light conditions (60 lx luminance intensity and 30 min light exposure time), the green LED ($520{\pm}5nm$) showed the highest attractive rate ($520{\pm}5nm$, 52.2 %), followed by the blue LED ($470{\pm}10nm$, 33.9 %), the yellow LED ($590{\pm}5nm$, 32.2 %), BLB (28.9 %), UV LED (365 nm, 22.8 %), the red LED ($625{\pm}10nm$, 14.5 %), the white LED (450-620 nm, 10.6 %), and IR LED (730 nm, 9.5 %). In addition, the green LED to P. interpunctella adults was approximately 1.81 times more attractive than BLB. These results indicate that the green LED could be most useful for monitoring of P. interpunctella adults.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.410-411
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• 2007

To investigate the ZnO LED which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF magnetron sputtering system. The p-type ZnO thin film, fabricated by means of the ampoule-tube method, was used to make the ZnO p-n junction, and its characteristics was analyzed. The ampoule-tube method was used to make the p-type ZnO based on the As diffusion, and the hall measurement was used to confirm that the p-type is formed. the current-voltage characteristics of the ZnO p-n junction were measured to confirm the rectification characteristics of a typical p-n junction and the low leakage voltage characteristics. Analysis of ZnO LED V-I curve will provide a very useful technology for producing the UV ZnO LED and ZnO-based devices.

• Korean Journal of Materials Research
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• v.27 no.6
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• pp.301-306
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• 2017

The discovery of new luminescent materials for use in light-emitting diodes(LEDs) has been of great interest, since LED-based solid state lighting applications are attracting a lot of attention in the energy saving and environmental fields. Recent research trends have centered on the discovery of new luminescent materials rather than on fine changes in well-known luminescent materials. In a sense, the novelty of our study beyond simple modification or improvement of existing phosphors. A good strategy for the discovery of new fluorescent materials is to introduce activators that are appropriate for conventional inorganic compounds, that have well-defined structures in the crystal structure database, but have not been considered as phosphor hosts. Another strategy is to discover new host compounds with structures that cannot be found in any existing databases. We have pursued these two strategies at the same time using composite search technology with particle swarm optimization(PSO). In this study, using PSO, we have tracked down a search space composed of Sr-Al-Si-O-N and have discovered a new phosphor structure with yellow luminescence; this material is a potential candidate for UV-LED applications.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.573-577
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• 2004

We have synthesized a Eu$^{2＋}$-activated Sr$_3$MgSi$_2$ $O_{8}$ blue phosphor and investigated an attempt to develop blue LEDs by combining it with a InGaN blue LED chip (Len=405 nm). The InGaN-based Sr$_3$MgSi$_2$ $O_{8}$：Eu LED Lamp shows two bands at 405 nm and 460 nm. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This 405 nm emission was used as an optical transition of the Sr$_3$MgSi$_2$ $O_{8}$：Eu phosphor. The 460 m emission band is ascribed to a radiative recombination of Eu$^{2＋}$ impurity ions in the Sr$_3$MgSi$_2$ $O_{8}$ host matrix. As a consequence of a preparation of W blue LED Lamp using the Sr$_3$MgSi$_2$ $O_{8}$：Eu blue phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/blue phosphor(1/0,202). At this time, the CIE chromaticity was x=0.1417 and y=0.0683.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.4
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• pp.156-159
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• 2007

The red emission properties of $Mn^{4+}$ doped $SrAl_{12}O_{19}$ prepared by the solid-state reaction was investigated, in order to verify its potential to act as the red emitting phosphor of white LEDs. The emission spectrum exhibits a narrow band between $600{\sim}700 nm $ with four sharp peaks occurring at about 643, 656, 666, 671 nm due to the $^2E\to^4A_2$ transition of $Mn^{4+}$. The excitation spectrum exhibits a broad band between $200{\sim}500 nm$ with three peaks occurring at about 338, 398 and 468 nm, respectively. Moreover, the relative emission intensity of $SrAl_{12}O_{19}:Mn^{4+}$ with or without $CaF_2$ and MgO fluxes measured at excitation source 390 nm. The relative emission intensity of $SrAl_{12}O_{19}:Mn^{4+}$ containing 0.67mol% MgO was approximately 30% higher than that of the base composition sample. Strontium hexa-aluminate measured at room temperature as a function of the substituted Mg concentration. MgO was added to replace part of the $Al_2O_3$. Also, the relative emission intensity of $SrAl_{12}O_{19}:Mn^{4+}$ containing 0.67 mol% MgO and 0.67 mol% $CaF_2$ was approximately about 48% higher than that of the base composition $SrAl_{12}O_{19}:Mn^{4+}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.3
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• pp.112-115
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• 2006

The red emission properties of $Bi^{3+}$ co-doped $Y_2O_3:Eu^{3+}$ prepared by the solid-state reaction was investigated, in order to verify its potential to act as the red emitting phosphor of white LEDs. The emission spectrum consisted of a weak band at 581, 587, 5931 and 599 nm, with maximum sharp peaks occurring at about 611 nm due to the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$, while the excitation spectrum exhibited a broad band between 290 and 430 mm with peaks occurring in the range of $310{\sim}390nm$. Also, SEM image of the sample containing 0.43 mol% $H_3BO_3$ and 2.08 mol% $BaCl_2{\cdot}2H_2O$ phosphor particles grew to achieve diameters of $700{\sim}800nm$.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.615-622
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• 2022

In this study, we sought to determine an appropriate LED light source that can be applied for the quality control of Aphidius colemani. Four LED light sources (385, 405, 450, and 660 nm) were evaluated in a Y-tube experiment (choice test) using a 5,000-k white LED as a control. The 385 nm LED light source was found to have attractant effect on A. colemani. In a no-choice test (Y-tube experiment) evaluating the remaining three LED light sources (385, 405, and 450 nm), the attractiveness of these light sources for A. colemani was high in the order 450 nm > 385 nm > 405 nm light, with no statistically significant differences between 450 nm and 385 nm. Given that 385 nm LED illumination may cause skin damage, we selected 450 nm LEDs for application in a device used for the quality control of A. colemani, which we subsequently demonstrated to have an attraction rate of 87.4%. We believe the findings of this study will make a valuable contribution to the quality control of natural enemies.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.1
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• pp.1-5
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• 2015

For the special usage, the effort of developing AlN single crystals has been very hot in the world. The AlN-base UV LEDs are used on the field of sterilization, purification, curing and analyzing, which can advance human's living and medical processes etc.. AlN single crystals were grown by the PVT (Physical vapor transport) method. On the growing process, carbon crucibles with three different types such as normal size, taller than normal and wider than normal were used for comparison. The processing temperature was in the range of $1900{\sim}2100^{\circ}C$ and ambient pressure was 200~1 Torr. When the taller crucible was used, the sublimation mass was greater than normal dimension one but the best condition of growth changes widely. However the wider one gave much sublimation mass and growing condition was more stable than normal dimension. On limited growing furnace system, the changes of crucible dimension of PVT method provide the change of best condition for growth rate, as-grown crystal quality and growth condition stability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.283-285
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• 2013

피부의 관리를 위한 방법 중 광을 이용한 케어는 비침습적인 방법으로 세포를 활성화 시켜 도움을 주는 매우 유용한 방법이다. 최근에는 낮은 에너지의 LED를 광원으로 이용하는 LLLT (Low Level Light Therapy)가 많이 적용이 된다. 본 논문에서는 피부 미용기기에서 많이 사용되고 있는 가시광 영역의 적색과 황색, 그리고 적외선 영역의 LED를 이용하여 array를 제작하였다. 제작된 LED array는 5V의 전압과 50mA의 전류로 구동되며, 적색이 평균 $10.7mW/cm^2$, 황색이 평균 $1.8mW/cm^2$, 적외선이 평균 $5.5mW/cm^2$의 광출력을 갖는다. 이를 배양된 human cell plate에 각각 10, 20, 40분의 시간으로 조사하였으며, LED array와 조사면 사이에 20 mm의 거리를 두어 균일한 광량이 조사 될 수 있도록 하였다. 실험결과, wound healing의 경우는 적색광을 조사하였을 때, injury line의 길이가 $604.36{\mu}m$에서 10분 조사 시 $368.92{\mu}m$, 20분 조사 시 $298.04{\mu}m$, 40분 조사 시 $491.22{\mu}m$로 줄어드는 효과를 보였으며 특히 20분간 조사하였을 경우의 효과가 가장 좋았다. Cell regeneration의 경우는 황색광을 20분간 조사하였을 경우에 UV 에 의해 손상된 세포 수가 가장 크게 줄어드는 것을 확인할 수 있었다. 결과적으로 photorejuvenation 효과를 줄 수 있는 wound healing과 cell regeneration에는 적색 및 황색광의 LED array를 20분간 조사하였을 때가 가장 효과적이었으며, 적외광의 경우에는 모든 실험에서 효과가 없음을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.101-101
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• 2010

ZnO shows a direct band gap of 3.37eV, large exciton binding energy (~60 meV), high oxidation ability, high sensitivity to many gases, and low cost, and it has been used in various applications such as transparent electrodes, light emitting diodes (LEDs), gas sensors and photocatalysts. Among these applications ZnO as photocatalyst has considerably attracted attention over the past few years because of its high activities in removing organic contaminants generated from industrial activities. In this research, ZnO nanoparticles were synthesized by spray-pyrolysis method using the zinc acetate dihydrate as starting material at synthesis temperature of $900^{\circ}C$ with concentration varied from 0.01 to 1.0M. The physical and chemical properties of the synthesized ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increased precursor concentration, a primary, secondary particle sizes of ZnO nanoparticles increased by 0.8 to $1.5{\mu}m$ and 15 to 35nm, and their crystallinity was improved. Methyleneblue (MB) solution ($1{\mu}M$) as a test comtaminant was prepared for evaluating the photocatalytic activities of ZnO nanoparticles synthesized in different precursor concentration. The results show that the photocatalytic efficiency of ZnO nanoparticles was gradually enhanced by increased precursor concentration.