• Journal of the Korean Ceramic Society
• /
• v.43 no.5 s.288
• /
• pp.304-308
• /
• 2006

We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the $Sr_3MgSi_2O_8:Eu$ and $(Sr,Ba)_2SiO_4$ host matrix. As a consequence of a preparation of UV White LED lamp using the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x = 0.3140, CIE y = 0.3201 and CCT (6500 K).

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.1
• /
• pp.29-38
• /
• 2015

Cyanide can be leached out from the cyanidation method which has been used to extract high-purity gold and silver from ores, and it becomes a variety of cyanide complexes associated with heavy metals contained in ores. Such cyanide complexes are considered as persistent and non-degradable pollutants which cause adverse effects on humans and surrounding environments. Based on binding force between heavy metals and cyanide, cyanide complexes can be categorized weak acid dissociable (WAD) and strong acid dissociable (SAD). This study comparatively evaluated the performance of photo-catalytic process with regard to forms of cyanide complexes. In particular, both effects of UV LED wavelength and surface modification of photo-catalyst on the removal efficiency of cyanide complexes were investigated in detail. The results indicate that the performance of photo-catalytic oxidation is significantly affected by the form of cyanide complexes. In addition, the effect of UV LED wavelength on the removal efficiency was quite different between free cyanide and cyanide complexes associated with heavy metals. The results support that the surface modification of photo-catalyst, such as doping can improve overall performance of photo-catalytic oxidation of cyanide complexes.

• Journal of Biosystems Engineering
• /
• v.39 no.2
• /
• pp.87-95
• /
• 2014

Purpose: The purpose of this study was to design a variable frequency LED light system for plant factory which combined red, blue, green, white, and UV lights and controlled the ratio of the light wavelength. In addition, this study evaluated the performance of each combination of LED to verify the applicability. Methods: Four combinations of LED (i.e. Red+Blue, Red+Blue+Green, Red+Blue+White, Red+Blue+UV) were designed using five types of LED. The system was designed to control the duty ratio of each wavelength of LED by 1% interval from 0~100%, the pulse by 1Hz interval from 1~20kHz. Response characteristics of the control system, spectral distribution of each combination, light uniformity and uniformity ratio were measured to test the performance of the system. Results: Clean waveforms were measured from 10Hz to 10kHz regardless of duty ratio. Frequency distortion was observed within 5% of inflection point at frequencies above 10kHz regardless of duty ratio, but it was judged negligible. Spectra showed a normal distribution, and maximum PPF with duty ratio of 100% was $271.4{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for the Red+Blue combination. PPF of the Red+Blue+Green combination was $258.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and that of the Red+Blue+White combination was $273.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. PPF of the Red+Blue+UV combination was $267.7{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Uniformity ratio for the area excepting border showed 0.90 for the Red+Blue and Red+Blue+White combinations, 0.87 for the Red+Blue+Green combination, and 0.88 for the Red+Blue+UV combination. The light was irradiated evenly at the area excepting border, so it was suitable for plant growing. Conclusions: From the results of this study, response characteristics of the control system, spectral distribution of each combination, light uniformity and uniformity ratio were suitable for applying into the plant factory.

• Electronics and Telecommunications Trends
• /
• v.30 no.6
• /
• pp.42-49
• /
• 2015

질화물 반도체 기반 가시광 청색 Light Emitting Diode(LED) 기술은 디스플레이의 Back Light Unit(BLU)뿐 아니라 일반 조명에 활용되며 우리 실생활에서 매우 밀접하게 사용하고 있다. 가시광보다 짧은 파장을 가지는 자외선 LED의 경우 경화기 및 위폐감지기에 기존의 유해 가스를 사용하는 자외선 램프를 대체하고 있다. 자외선 광원의 또 다른 거대 시장으로 살균 및 정화, 의료 및 바이오 응용 시장에서 자외선 램프를 대체할 수 있는 자외선 LED 기술이 활발히 발전하고 있다. 본고에서는 이들 자외선광원 시장동향과 국내외 자외선 LED의 기술동향을 파악하므로 앞으로 연구개발의 방향을 모색하고자 한다.

• Electronics and Telecommunications Trends
• /
• v.25 no.5
• /
• pp.59-71
• /
• 2010

피부질환 치료를 위한 광선요법은 태양광, 레이저, 형광등, UV 램프 등 다양한 광원을 이용하여 광이 피부 내에서 생화학적 반응을 촉진하는 원리를 이용하여 피부 조직의 선택적 재생 또는 파괴 등을 통해 손상된 피부를 치료하는 광 의료 기술이다. 최근 발전하고 있는 LED 광원 기술은 광선요법에서 시용되어온 광원을 대체할 수 있는 기술로 각광을 받고 있다. 이에 본 고에서는 광선요법과 관련된 기초 원리를 살펴보고, LED가 피부질환 치료용 광원으로 사용될 때 고려되어야 하는 임상적, 기술적 문제점과 다양한 피부질환 치료에 있어서 LED 광원의 역할에 대해 살펴 보았다. 아울러, 피부질환 치료용 LED 치료기 관련 국내외 연구 개발 동향과 기업들이 출시한 LED 치료기의 특성을 살펴보았다. LED 치료기 관련 표준화 동향과 국내외 지식재산권 현황을 살펴보았으며, 향후 LED 기반의 피부질환 치료기의 개발 방향을 모색하였다.

• International Journal of Internet, Broadcasting and Communication
• /
• v.15 no.2
• /
• pp.157-167
• /
• 2023

As a new trend in the development of urban public spaces, the use of right-angle LED screens perfectly combines building facades with naked-eye 3D visual effects, providing designers with a brand-new creative platform. How to create a realistic naked-eye 3D effect on a right-angle LED screen and bring an immersive visual experience to the audience has become a question worth exploring. So far, production companies have yet to announce the relevant design ideas and complete production methods. In order to explore the production principle and production process of the naked-eye 3D effect of the right-angle LED screen, we summarize the basic production principle of the naked-eye 3D impact of the right-angle LED screen through case analysis. Based on understanding the production principle, the actual case production test was carried out, and a complete production process of the naked eye 3D visual effect of the right-angle led screen was tried to be provided by off-line rendering. For the problem of how to deal with image deformation, we provide two production methods: post-production software correction and UV mapping. Among them, the UV mapping method is more efficient and convenient. Referring to this paper can help designers quickly understand the production principle of the naked eye 3D effect of right-angle LED screens. The production process proposed in this paper can provide a reference for production method for related project producers.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.6 no.3
• /
• pp.199-205
• /
• 2006

Patterned sapphire substrates (PSS) were fabricated by a simple wet etching process with $SiO_2$ stripe masks and a mixed solution of $H_2SO_4$ and $H_3PO_4$. GaN layers were epitaxially grown on the PSS under the optimized 2-step growth condition of metalorganic vapor deposition. During the 1st growth step, GaN layers with triangular cross sections were grown on the selected area of the surface of the PSS, and in the 2nd growth step, the GaN layers were laterally grown and coalesced with neighboring GaN layers. The density of threading dislocations on the surface of the coalesced GaN layer was $2{\sim}4\;{\times}\;10^7\;cm^{-2}$ over the entire region. The epitaxial structure of near-UV light emitting diode (LED) was grown over the GaN layers on the PSS. The internal quantum efficiency and the extraction efficiency of the LED structure grown on the PSS were remarkably increased when compared to the conventional LED structure grown on the flat sapphire substrate. The reduction in TD density and the decrease in the number of times of total internal reflections of the light flux are mainly attributed due to high level of scattering on the PSS.

• Information Display
• /
• v.17 no.1
• /
• pp.11-17
• /
• 2016

• Electrical & Electronic Materials
• /
• v.25 no.9
• /
• pp.35-43
• /
• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.855-856
• /
• 2011