• 제목/요약/키워드: white LEDs

검색결과 224건 처리시간 0.062초

Phosphors development for LED and PDP Applications

  • Park, Hee-Dong
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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    • pp.368-369
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    • 2003
  • The recent development of InGaN-based white light emitting diodes (LEDs) has expanded their potential applications in areas such as white electric home appliances, backlight for mobile phone or notebook PC, and indoor lightings. In this lecture, recent researches related to the phosphors for LEDs applications and their luminescent properties were reviewed. PDPs are considered as the most potential flat panel displays with a large-screen size. Phosphors in PDPs directly affect the brightness and lifetime. So, many researchers have tried to improve the luminescence characteristics of the phosphors especially under vacuum ultraviolet (VUV) excitation. We overviewed recent research trends and conclusive achievements for the PDP phosphors.

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고휘도 발광다이오드(LED)의 광학적 특성에 관한 연구 (A Study of Optical Characteristics for High Intensity LED)

  • 황명근;임종민;신상욱
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 C
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    • pp.2159-2161
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    • 2000
  • The LEDs are used for signal lights including traffic signals and telecommunication equipments. Advanced foreign countries are making R&D of ultra high intensity LEDs, and the LEDs are expected to new light source. Optical characteristics by measurements of 14 LEDs; each 2 of 3$\Phi$ R/G/Y LEDs, each of 5$\Phi$ Y/G/Y LEDs and each of high intensity 5$\Phi$ R/G/B/A/W LEDs. Comparison on chromaticity coordinate of high intensity 5$\Phi$ White LED by forward V/I.

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고 출력 백색 변환용 LED(3W용)의 고장메커니즘 비교 (A Comparison of the Failure Mechanism for High Power Converted White LEDs(3W))

  • 윤양기;장중순
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제12권3호
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    • pp.177-186
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    • 2012
  • This paper presents a comparison of the failure mechanism for high power converted white LEDs(3W) with the commercially available YAG:Ce and silicate phosphor. We carry out the normal aging life test for 10,000 hours, the high temperature aging test for 8,000 hours, the high temperature and humidity aging test for 8,000 hours and the current aging testing for 5,000 hours. The optical and electrical parameters of LEDs were monitored, such as lumen, correlated color temperature (CCT), chromaticity coordinates(x, y), thermal resistance, I -V curve and spectrum intensity. The stress induced a luminous flux decay on LED in all experiments and causes a failure. So we try to find out what's a main failure mechanism for a high power LED.

Effect of Wavelength-dependent Scattering on the Color Chromaticity of the LCD Backlight

  • Kwon, Jin Hyuk;Jun, Hwa Joon;Gwag, Jin Seog;Lee, Hong Su
    • Journal of the Optical Society of Korea
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    • 제17권3호
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    • pp.275-278
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    • 2013
  • The effect of the wavelength-dependent scattering on the change of the color chromaticity in the lightguide panel of a liquid crystal display is examined. The white light emitted from the white LEDs located at the edge of the lightguide propagates in the lightguide and is scattered by the patterned dots that are placed on the bottom of the lightguide. The scattered lights that are far from the LEDs showed reddish color compared to the bluish color that is scattered from the near area from the LEDs. The color difference was between 0.01 to 0.06 depending on the resin and the thickness of the lightguide.

Wide bandgap III-nitride semiconductors: opportunities for future optoelectronics

  • Park, Yoon-Soo
    • 한국결정성장학회지
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    • 제12권1호
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    • pp.11-20
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    • 2002
  • The world at the end of the $20^{th}$ Century has become "blue" Indeed, this past decade has witnessed a "blue rush" towards the development of violet-blue-green light emitting diodes (LEDs) and laser diodes (LDs) based on wide bandgap III-Nitride semiconductors. And the hard work has culminated with, first, the demonstration of commercial high brightness blue and green LEDs and of commercial violet LDs, at the very end of this decade. Thanks to their extraordinary properties, these semiconductor materials have generated a plethora of activity in semiconductor science and technology. Novel approaches are explored daily to improve the current optoelectronics state-of-the-art. Such improvements will extend the usage and the efficiency of new light sources (e.g. white LEDs), support the rising information technology age (e.g. high density optical data storage), and enhance the environmental awareness capabilities of humans (ultraviolet and visible photon detectors and sensors). Such opportunities and many others will be reviewed in this presentation.

Promoted Growth and Development of Carnation Plantlets In Vitro by Ventilation and Combined Red and Blue Light

  • Nguyen, Quan Hoang;Thi, Luc The;Park, Yoo Gyeong;Jeong, Byoung Ryong
    • 화훼연구
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    • 제26권4호
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    • pp.166-178
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    • 2018
  • In this study, the principal objective was to investigate the effect of light quality and vessel ventilation on the growth and development, physiology, activities of antioxidant enzymes, and contents of mineral nutrients of carnation (Dianthus caryophyllus L.) 'Marble Beauty'. Single node cuttings stuck into the plant growth regulator (PGR)-free MS medium in containers covered with caps with or without a ventilation filter were cultured first four weeks under white and then additional four weeks under either white (control), blue, red, or red + blue light emitting diodes (LEDs) for 56 days. Interestingly, a ventilated culture condition not only reduced the percentage of the hyperhydricity, but also increased the total chlorophyll content (Chl a + Chl b) of the plantlets as compared to the non-ventilated condition. In addition, blue LEDs produced plantlets with the greatest number of shoots and red LEDs produced plantlets with the greatest shoot length. The quality of plantlets was improved under a ventilation condition. Besides, under a ventilated condition, red + blue LEDs raised APX activity, and blue LEDs not only raised the activity of the CAT, but also increased tissue contents of such elements as K, Ca, Mg, Zn, Mn and Fe. The red LEDs increased contents of B and Si under a ventilated condition, and Na accumulation under a non-ventilated condition. Thus, including blue or red LEDs as the light source in a ventilated culture condition will produce plantlets of carnation 'Marble Beauty' in vitro with improved quality.

The Latest Technology Trend of LED Phosphors

  • Yoon, Chul-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.1349-1349
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    • 2008
  • The applications of white LEDs has been expanded from mobile phone to LCD TV as a backlight source recently and now are penetrating into the lighting market. With these changes new requirements for LEDs phosphors are demanded. In this point of view recent technology trend of phosphors for LCD backlight and lighting will be discussed.

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복합환경 시스템 구동을 위한 센서응용 분석

  • 김종만;김원섭
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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    • pp.283-283
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    • 2009
  • Composition environments - Automatic Control System based on Sproute Cultivator using Remote Conditional Driving System was realized. It was carried out to investigate into the characteristics of LEDs Control for the cultivation of sprouts. We have also composed a Combined Automatic Control System possible for the control of temperature and humidity at the same time. The applied LEDs for measurement are blue, green, red, white, yellow leds. And we had also designed the Web Programming for the automatic control about sprout cutivators.

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LED의 색온도에 따른 밝음의 느낌에 관한 연구 (A Study on Visual Clarity According to Color Temperature of LEDs)

  • 이진우;함승우
    • 조명전기설비학회논문지
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    • 제28권3호
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    • pp.14-17
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    • 2014
  • We studied visual clarity according to the difference of color temperature by using black and white printed paper and four sheets of colored paper under LEDs. We tested students in their twenties, under 3,000, 4,000, 5,700 and 6,500K LEDs (Ra=80). The results show visual clarity is proportioned to color temperature.