• Title/Summary/Keyword: blue chip

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Application of $Sr_3SiO_5$:Eu yellow phosphor for white light-emitting diodes

  • Park, Joung-Kyu;Kim, Chang-Hae;Park, Hee-Dong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.676-678
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    • 2004
  • In order to develop new yellow phosphor that emit efficiently under the 450 - 470 nm excitation range, we have synthesized a $Eu^{2+}$-activated $Sr_3SiO_5$ yellow phosphor and investigated an attempt to develop white LEDs by combining it with a InGaN blue LED chip (460 nm). Two distinct emission bands from the InGaN-based LED and the $Sr_3SiO_5$:Eu phosphor are clearly observed at 460 nm and at 570 nm, respectively. These two emission bands combine to give a spectrum that appears white to the naked eye. Our results showed that InGaN (460 nm chip)-based $Sr_3SiO_5$:Eu exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

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Effect of Yellow Phosphor on Characteristics of White Light Emitting Diode (백색 발광다이오드의 특성에 대한 황색 형광체의 영향)

  • Chang, Ho-Jung;Son, Chang-Sik;Hur, Jae-Sung
    • Journal of the Korean institute of surface engineering
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    • v.40 no.2
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    • pp.103-106
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    • 2007
  • We have investigated the optical and electrical properties of surface mounted white light emitting diode (LED) chips prepared by using yellow phosphors on the blue LED chip. The yellow phosphor mixed with transparent epoxy was coated on the prepared LED chip. The optimum mixing conditions with epoxy and yellow phosphor is obtained at the mixing ratio of epoxy:yellow phosphor = 97:3 wt%. The maximum luminance and light emitting efficiency are above $80,000cd/m^2$ and 23.2 lm/W, respectively, at the bias voltage of 2.9 V. There was no distinct change in the luminance strength with changing of the yellow phosphor ratios. The current of the white LED chip is about 30 mA at 2.9 V.

A Study on the III-nitride Light Emitting Diode with the Chip Integration by Metal Interconnection (금속배선 칩 집적공정을 포함하는 질화물 반도체 LED 광소자 특성 연구)

  • 김근주;양정자
    • Journal of the Semiconductor & Display Technology
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    • v.3 no.3
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    • pp.31-35
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    • 2004
  • A blue light emitting diode with 8 periods InGaN/GaN multi-quantum well structure grown by metal-organic chemical vapor deposition was fabricated with the inclusion of the metal-interconnection process in order to integrate the chips for light lamp. The quantum well structure provides the blue light photoluminescence peaked at 479.2 nm at room temperature. As decreasing the temperature to 20 K, the main peak was shifted to 469.7 nm and a minor peak at 441.9 nm appeared indicating the quantum dot formation in quantum wells. The current-voltage measurement for the fabricated LED chips shows that the metal-interconnection provides good current path with ohmic resistance of 41 $\Omega$.

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Wide Color Gamut Backlight from Three-band White LED

  • Kim, Il-Ku;Chung, Kil-Yoan
    • Journal of the Optical Society of Korea
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    • v.11 no.2
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    • pp.67-70
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    • 2007
  • A Wide Color Gamut Backlight system was studied using a three-band white Light-Emitting Diode. A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 445-nm blue peak, and a green phosphor and red phosphor that emit 535-nm green and 621-nm red peak emissions, respectively, when excited by 450-nm blue light. Using for this three-band white LED, wide color gamut backlight unit (BLU) was attained. The luminance of BLU and CIE 1931 chromaticity coordinates was $1,700Cd/m^2$ and (0.337, 0.346). Color filter matching simulations for this configuration show that the three-band white LED backlight can be enhanced by up to 16% over conventional white LED backlight color gamut.

Electrochemical measurement for analysis of DNA sequence (DNA 염기서열 분석을 위한 전기 화학적 측정법)

  • Jo, Seong-Bo;Hong, Jin-Seop;Kim, Yeong-Mi;Park, Jeong-Ho
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.2
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    • pp.92-97
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    • 2002
  • One of the important roles of a DNA chip is the capability of detecting genetic diseases and mutations by analyzing DNA sequence. For a successful electrochemical genotyping, several aspects should be considered including the chemical treatment of electrode surface, DNA immobilization on electrode, hybridization, choice of an intercalator to be selectively bound to double standee DNA, and an equipment for detecting and analyzing the output signal. Au was used as the electrode material, 2-mercaptoethanol was used for linking DNA to Au electrode, and methylene blue was used as an indicator that can be bound to a double stranded DNA selectively. From the analysis of reductive current of this indicator that was bound to a double stranded DNA on an electrode, a normal double stranded DNA was able to be distinguished from a single stranded DNA in just a few seconds. Also, it was found that the peak reduction current of indicator is proportional to the concentration of target DNA to be hybridized with probe DNA. Therefore, it is possible to realize a sim71e and cheats DNA sensor using the electrochemical measurement for genotyping.

Preparation, Characterization and Photoluminescence Properties of Ca1-xSrxS:Eu Red-emitting Phosphors for a White LED

  • Sung, Hye-Jin;Cho, Young-Sik;Huh, Young-Duk;Do, Young-Rag
    • Bulletin of the Korean Chemical Society
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    • v.28 no.8
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    • pp.1280-1284
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    • 2007
  • A series of Ca1-xSrxS:Eu (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) phosphors were synthesized by solid-state reactions. The Ca1-xSrxS:Eu phosphors have a strong absorption at 455 nm, which corresponds to the emission wavelength of a blue LED. The emission peak of Ca1-xSrxS:Eu is blue shifted from 655 to 618 nm with increasing Sr content. The characteristics of Ca1-xSrxS:Eu phosphors make them suitable for use as wavelengthtunable red-emitting phosphors for three-band white LEDs pumped by a blue LED. In support of this, we fabricated a three-band white LED by coating SrGa2S4:Eu and Ca0.6Sr0.4S:Eu phosphors onto a blue LED chip, and characterized its optical properties.

Correlation between the Active-Layer Uniformity and Reliability of Blue Light-Emitting Diodes (청색 발광 다이오드에서 활성층의 균일성과 신뢰성 사이의 상관관계 고찰)

  • Jang Jin-Won;Kim Sang-Bae
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.42 no.12
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    • pp.27-34
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    • 2005
  • We have investigated the correlation between the active-layer uniformity and reliability of InGaN/GaN blue LEDs. According to initial characteristics, the devices are classified into two groups: group I devices of uniform light-emission and group II devices of non-uniform light-emission. The group II devices are more dependent on temperature and we have found two degradation mechanisms through reliability test. One is bulk degradation in which the degradation occurred over the entire chip and another one is edge degradation in which the degradation occurred from the edge of the chip. Bulk degradation caused by the nonradiative defects is found to be faster in group II devices while there is no difference in the rate of the much faster edge degradation, where darkening starts from the n-Ohmic contact edge. Therefore, more uniform active layer, more uniform current spreading, and the passivation of the dry-etched side-wall are essential for the high reliability of InGaN/GaN LEDs.

The extraction and application of the color chip represented in the work of Picasso according to his muses (피카소의 작품에 나타난 뮤즈별 컬러 칩 도출과 적용)

  • Lee, Keum Hee
    • The Research Journal of the Costume Culture
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    • v.23 no.2
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    • pp.193-212
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    • 2015
  • The purpose of this study is to analyze the characters and images of Picasso's muses, to extract the color chip from the works of Picasso, and to apply these results to fashion design. The study includes a literature review, an analysis of visual materials. The results are as follows. Fernande, who was cheerful and voluptuous, was depicted with pink-brown, a few browns, grey, black, white, and green and represents an ethnic and elegant image. Eva, a star-crossed lover, was depicted with a few browns, black, and pale-yellow and represents a gorgeous and natural image. Olga, who was jealous and sickly wife, was depicted with a few blues, browns and neutral-color and represents a classic and dandy image. Th${\acute{e}}$r${\grave{e}}$se, who was innocent and sweet, was depicted with the bright and pastel colors of red, green, violet, and yellow and of white, blue, brown, and black and represents a romantic, pretty, and casual image. Dora, who was intellectually and emotionally- challenging, was depicted with the strong colors of red, yellow, green, and blue, which are in contrast to black and also to white, grey and brown and represents a wild and dynamic image. Gilot, who was strong-willed and prideful, was depicted with the symbolic color of green, a color contrasting with black and white, grey, and pale brown and represents a clear, cool casual and modern image. Jacqueline, the self-giving and reclusive wife, was depicted with deep red, blue, green, black, white, dark brown, grey represents a formal, dandy, and chic image.

ASIC Design Controlling Brightness Compensation for Full Color LED Vision

  • Lee Jong Ha;Choi Kyu Hoon;Hwang Sang Moon
    • Proceedings of the IEEK Conference
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    • 2004.08c
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    • pp.836-841
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    • 2004
  • This paper describes ASIC design for brightness revision control, A LED Pixel Matrix (LPM) design and LPM in natural color LED vision. A designed chip has 256 levels of gradation correspond to each Red, Green, Blue LED pixel respectively, which have received 8bit image data. In order to maintain color uniformity by reducing the original rank error of LED, we adjusted the specific character value 'a' and brightness revision value 'b' to pixel unit, module unit and LED vision respectively by brightness characteristic function with 'Y=aX+b'. In this paper, if designed custom chip and brightness revision control method are applied to manufacturing of natural color LED vision, we can obtain good quality of image. Furthermore, it may decrease the cost for manufacturing LED vision or installing the plants.

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Synthesis of the sulfide phosphors and white light generation based on InGaN chip

  • Kim, Kyung-Nam;Kim, Jae-Myung;Choi, Kyoung-Jae;Park, Joung-Kyu;Kim, Chang-Hae
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.679-682
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    • 2004
  • $SrGa_2S_4$:Eu green phosphor and SrS:Eu red phosphor have been synthesized by co-precipitation method, respectively. Two sulfide phosphors were influenced by oxygen defect in host materials. Excitation spectra of these phosphors have high efficiency at the long wavelength region. And emission efficiency is increased under the excitation wavelength of 465nm. The combination of thiogallate green phosphor and sulfide red phosphor based on blue light InGaN chip has made it possible to emit white light.

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