• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.769-772
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• 2008

For several years, many researchers have proposed LED backlight dimming technology for low power consumption and high contrast ratio. One of the major issues plaguing RGB LED with 2D dimming technology is color shift. This undesirable variation makes it difficult to use RGB LED as light sources in the backlight system. This paper describes the useful method of the optical feedback system for 2D dimming RGB LED backlight. The test results show that our proposed method is very suitable for the 2D dimming technology.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.887-890
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• 2008

We present 2D slab silicon-based photonic crystal optical insulator to enhance light emission efficiency of light-emitting diode (LED). A 2D slab silicon photonic crystal is designed in such a way that light emitting diode die can be placed in the middle of the silicon photonic crystal. The device creates light propagation forbidden region in horizontal plane for Transverse Electric (TE) light with the wavelength range of 450 nm to 600 nm.

• Applied Science and Convergence Technology
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• 제25권1호
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• pp.1-6
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• 2016

Quantum dots (QDs) are considered as excellent color conversion and self-emitting materials for display and lighting applications. In this article, various technologies which can be used to realize white light emission with QDs are discussed. QDs have good color purity with a narrow emission spectrum and tunable optical properties with size control capabilities. For white light emission with a color-conversion approach, QDs are combined with blue-emitting inorganic and organic light-emitting diodes (LED) to generate white emission with high energy conversion efficiency and a high color rendering index for various display and lighting applications. Various device structures for self-emitting white QD light-emitting diodes (QD-LED) are also reviewed. Various stacking and patterning technologies are discussed in relation to QD-LED devices.

• 한국산림과학회지
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• 제99권5호
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• pp.750-754
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• 2010

Among the environmental conditions employed in micropropagation, light quality plays an important role in growth, specially morphogenesis and photosynthesis. The effect of radiation quality (350-740 nm) on the development and growth of zygotic embryos and in vitro plantlets of open-pollinated chestnut (Castanea crenata S. et Z.) were studied. Two types of explants were exposed for 4 weeks to cool white (W, as control), monochromatic red (R, peak emission 650 nm), monochromatic blue (B, peak emission 440 nm), red+blue (R+B, 1:1), or red+far-red (R+Fr, 1:1, far-red peak emission 720 nm) radiation from a light-emitting-diode (LED) system. While the zygotic embryos showed positive photoblastic behavior, their germination was inhibited by blue radiation. Hypocotyl elongation and root development were promoted by red radiation. The emergence of primary leaf and its expansion were faster under blue than under red radiation. In the plantlets, red and red+far-red radiation significantly increased the formation and growth of the root, whereas blue light reduced rooting. Therefore, radiation quality appears to influence some steps in the development of zygotic embryos and plantlets in the chestnut.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.897-902
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• 1998

We prepared Organic LED with a two layer structure by vacuum evaporation. The diode consisted of hole transfer layer (thickness of 30, 50, 70 nm) and electron transfer layer (thickness of 70, 50, 30 nm) material, which was N, N'-diphenyl- N, N'-bis-(3-methyl phenyl)-1,1'-diphenyl-4,4'-diamine)(TPD) and tris(8-hydroxy quinoline) aluminum(Alq3), respectively. We investigated EL properties of the LED with various thickness and cathode electrode. The best results were obtained when thickness of the electron layer is equal to that of emission layer and when AlLi alloy was used as a cathode. The EL intensity, luminance and efficiency of organic LED with equal of layer thick were improved seven, three and two times, respectively. Alq3 was ionized by carrier injection from cathode and could produce exitons. After electron-hole pairs were formed by combination of the electrons and holes at the emission layer, Alq3 layer emitted light.

• 한국광학회지
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• 제18권2호
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• pp.155-161
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• 2007

본 논문에서는 GaN/InGaN 다중양자우물(MQW)의 청색 발광 다이오드(LED)에서의 3차원적인 전류 및 2차원적인 광 분포를 보여 주기 위해 새롭고 간단한 3차원 회로 모델링과 해석이 처음으로 제안되었으며 이를 실험적으로 검증하였다. LED의 회로 파라미터들은 금속 및 에피 박막의 저항과 다이오드만으로 이루어져 있으며 각각의 파라미터는 전송선 모델(TLM) 및 전압-전류의 특성으로부터 얻을 수 있다. 제안된 방법과 회로 파라미터를 상부로 발광하는(top-surface emitting) LED에 적용하여 금속 및 에피 박막의 각 저항 변화에 따라 활성층을 지나가는 전류 분포의 효과를 정량적으로 해석하였다. 그리고 제작된 청색 LED 소자의 발광 분포는 p-전극 주위에서 어두운 발광 분포를 보이는 해석 결과와 유사한 경향을 보여주었다.

• Journal of Ginseng Research
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• 제36권2호
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• pp.198-204
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• 2012

An light-emitting diode (LED)-based light source was used as a monochromatic light source to determine the responses of raw ginseng roots (Panax ginseng Meyer) to specific emission spectra with respect to the production of ginsenosides. The ginsenoside content in the ginseng roots changed in response to the LED light treatments at $25^{\circ}C$ relative to the levels in the control roots that were treated in the dark or at $4^{\circ}C$ for 7 d. Ginseng roots were exposed to LEDs with four different peak emission wavelengths, 380, 450, 470, and 660 nm, in closed compartments. Compared with the control $4^{\circ}C$-treated roots, roots that were treated with 450 and 470 nm light showed a significantly increased production of ginsenosides (p<0.05), with increases of 64.9% and 74.1%, respectively. The contents of the ginsenosides $Rb_2$, Rc, and $Rg_1$ were significantly higher (p<0.05) in the 450 and 470 nm-treated root samples. The ratio of protopanaxadiol ginsenosides ($Rb_1$, $Rb_2$, Rc, and Rd) to protopanaxatriol ginsenosides ($Rb_1$, $Rb_2$, Re, and Rf) was significantly higher (p<0.05) in the 450 and 470 nm-treated root samples than in the control $4^{\circ}C$-treated roots. This is the first report that demonstrates the increase and conversion of ginsenosides in raw ginseng roots in response to exposure to LED light.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.286.1-286.1
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• 2013

Nowadays, the glare towards the light-emitting diode (LED) lighting source has much attention due to its eco-friendly nature, reduced energy consumption, and low CO2 emission. LEDs can show versatile colors by changing the composition ratio of semiconductors. Phosphors re-emit light by absorbing light from LED, which is the key factor for emission. The endeavor to make replica of natural white light is increasing day by day. Industrially, blue LED chip crowned with a yellow phosphor coated lens gives low quality white light. Newly, many researchers are introducing modern approaches, adding red phosphor to the yellow phosphor to increase the quality of white light. Here, we synthesized structurally and chemically stable europium doped oxyapatite Ca8Gd2(PO4)6O2 nano-crystalline structures by a hydrothermal method. The ultrafine structures were formed due to the effect of ethylenediaminetetraacetic acid, which is confirmed by the transmission electron microscope images. The structural properties were analyzed using the X-ray diffraction patterns.

• 한국통신학회논문지
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• 제36권9B호
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• pp.1108-1116
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• 2011

실내 가시광 무선 통신 기술은 반도체인 LED (Light Emitted Diode)의 발광 특성을 제어하여 디지털 신호를 송신하며, PD (Photo Diode)를 이용하여 광 신호를 송수신하는 차세대 무선 통신 기술이다. 이러한 가시광 무선통신에서 LED는 실내 조명기기로써의 역할 뿐 아니라 우선 통신 시스템의 송신기의 역할도 수행한다. 가시광 무선 통신 시스템은 그 특성 상 통신 영역이 빛의 도달하는 범위로 한정되며, 빛의 광량에 따라 통신 채널 품질이 결정된다. 이에 본 논문에서의 복수의 LED로 구성된 LED 패널의 위치 변화와 LED 발광 각도 변화가 통신 채널 품질에 미치는 영향을 분석하고자 한다. 이를 위한 모의실험을 수행하였고, 그 결과 LED 패널의 위치 및 LED 발광 각도가 조도 및 SNR 변화에 상당한 영향을 끼친다는 사실을 입증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.85-88
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• 1998

Light-emitting diode(LEDs), diode arrays, and phosphor display panels are finding increased use in a variety of commercial applications. Present and anticipated application of these devices include solid state indicator(e.g., digital clocks, meter readout) and display systems(e.g., instrument panels, TV display), the application being determined by the light -output capability and size availability(cost) of the particular device. In this work, Phosphor based on ZnS:Cu are used. Relation by luminance with the thickness of insulating layer and phosphor layer are discussed. Increased thickness of insulating layer are stable on voltage to 300V. By considering thickness and voltage, optimal structure and thickness are investigated. Also in order to maximize even surface emission, various sieving process are introduced. Very similar phosphor particle size is selected. Luminance by various wave intensity is also investigated. 150cd/m$^2$ luminance are investigated in stable voltage and frequency.