• Journal of Information Display
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• 제4권2호
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• pp.13-18
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• 2003

We synthesized bis (2-methyl-8-quinolinolato)(triphenylsiloxy) aluminum (III) (SAlq), a blue-emitting material having a high luminous efficiency, through a homogeneous-phase reaction. The photoluminescence (PL) and electroluminescence (EL) spectra of SAlq show two peaks at 454 nm and 477 nm. Efficient white light-emitting devices are fabricated by doping SAlq with a red fluorescent dye of 4-dicyanomethylene-2-methyl-6-{2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8yl) vinyl}-4H-pyran (DCM2). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCM2 results in light-emission of both blue and orange colors. Devices with the structure of ITO/TPD (50 nm)/SAlq:DCM2 (30 nm, 0.5 %)/$Alq_3$ (20 nm)/LiF (0.5 nmj/Al show EL peaks at 456 nm and 482 nm originating from SAlq and at 570 nm from DCM2, resulting in the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.37). The device exhibits an external quantum efficiency of about 2.3 % and a luminous efficiency of about 2.41m/W at 100 $cd/m^2$. A maximum luminance of about 23,800 $cd/m^2$ is obtained at the bias voltage of 15 V.

• 전자공학회논문지 IE
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• 제43권2호
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• pp.1-6
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• 2006

Two-wavelength에 의한 백색 유기발광소자를 청색계열의 발광재료 DPVBi와 오렌지계열의 발광재료 Rubrene 물질을 사용하여 제작하였다. 소자의 구조는 glass/ITO/TPD$(225{\AA})$/DPVBi/Rubrene/BCP$(210{\AA})/Alq_3(225{\AA})/Al(1000{\AA})$로 하였다. 청색 발광층인 DPVBi와 오렌지색 발광층인 Rubrene층의 두께비율를 변화시켜 가면서 백색광을 구현하였다. 청색발광재료 DPVBi층의 두께가 210${\AA}$ 이고 오렌지색 발광재료의 Rubrene 층의 두께가 180${\AA}$일 때 구동전압 15V에서 $1000cd/m^2$ 휘도와 (0.29, 0.33)의 CIE 색좌표값을 갖는 백색광을 얻었다.

• 대한화학회지
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• 제50권2호
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• pp.137-140
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• 2006

Eu2+를 활성제로 한(Sr,Ba)2Ga2SiO7 녹색 형광체를 일반적인 고상 반응으로 합성하였고, 그 합성된 형광체의 광발광 특성을 연구하였다. 형광체 제조 시, 마노유발에서 보다 효과적인 혼합을 위하여 아세톤을 사용하여 혼합하였다. 또한 25%H2/75%N2의 혼합기체를 이용한 환원조건에서 단순한 공정으로 형광체를 합성하였다. 이 형광체는 405 nm의 여기 파장하에서 효율적으로 발광되는 녹색 밴드(513 nm)를 갖고 있기 때문에 백색 LED(Light Emitting Diode)램프에 응용할 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.473-477
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• 2015

본 논문에서는 인광물질을 포함하는 조명용 백색 LED를 이용한 가시광 통신 시스템의 변조 대역폭을 늘리기 위한 등화기를 설계하고 실험적으로 결과를 보였다. 등화기의 성능을 분석하기 위한 해석적 방법으로 회로 시뮬레이터인 PSpice를 이용하였다. 등화기는 저항과 커패시터를 이용한 수동필터와 증폭기를 이용한 능동필터의 조합으로 구성하였다. 등화기를 수신단에 적용함으로써 3.5 MHz 부근의 인광성 백색 LED 변조 대역폭이 청색 광학필터를 사용하지 않고도 25 MHz 까지 확장되었다. 상용화된 라운드형 백색 LED 1개와 PIN형 광 다이오드 1개를 이용하여 구현한 가시광 통신 시스템에서 진폭편이변조 방식으로 변조된 LED의 가시광 신호는 1미터 거리에서 35 Mbit/s 데이터 전송률을 보였다. 이때의 비트 에러율은 $7.6{\times}10^{-4}$이었으며 이는 순방향 오류 정정의 한계인 $3.8{\times}10^{-3}$ 이하를 만족하였다.

• ETRI Journal
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• 제43권6호
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• pp.1093-1102
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• 2021

Microdisplays based on organic light-emitting diodes (OLEDs) have a small form factor, and this can be a great advantage when applied to augmented reality and virtual reality devices. In addition, a high-resolution microdisplay of 3000 ppi or more can be achieved when applying a white OLED structure and a color filter. However, low luminance is the weakness of an OLED-based microdisplay as compared with other microdisplay technologies. By applying a tandem structure consisting of two separate emission layers, the efficiency of the OLED device is increased, and higher luminance can be achieved. The efficiency and white spectrum of the OLED device are affected by the position of the emitting layer in the tandem structure and calculated via optical simulation. Each white OLED device with optimized efficiency is fabricated according to the position of the emitting layer, and red, green, and blue spectrum and efficiency are confirmed after passing through color filters. The optimized white OLED device with color filters reaches 97.8% of the National Television Standards Committee standard.

• 한국환경과학회지
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• 제21권6호
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• pp.757-761
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• 2012

The purpose of this study was to determine optimum conditions for the cultivation of Tetraselmis suecica (T. suecica) under illumination of four different types of LEDs (i.e., blue, red, white, and mixed). Initial cell concentration was $4{\times}10^4$ cells/mL and temperature of reactor was maintained between 21-$24^{\circ}C$. Specific growth rates were 0.72 $day^{-1}$(white), 0.58 $day^{-1}$(red), 0.49 $day^{-1}$(mixed), and 0.49 $day^{-1}$(blue). Thus, white LEDs was used for the cultivation of T. suecica. Tests with white LEDs under different light intensity, which was conducted to determine optimum light intensity of white LEDs, showed that 9,000 lux of illumination resulted in fastest cell growth and greatest cell concentrations. To avoid shadow effects by dense cell populations, aeration was performed. Cell concentration increased 3.8 times when aeration was used.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.324-325
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• 2006

In order to develop high efficiency white organic light-emitting diodes (OLEDs), OLED devices consisted of red and blue emitting layers (EMLs) were fabricated and the effect of respective layer thickness and the order of layer stacking on the luminous efficiency was evaluated Red/blue structure showed higher efficiency than blue/red, due to the higher exiton formation. In the blue layer of red/blue structure. However, the efficiency of the red/blue significantly depended on the thickness of the red layer, whereas the thickness of the blue layer was not affect so much. The optimum thickness of the red layer was 20 ${\AA}$, where the luminous and power efficiencies were 155 cd/A and 10.51 lm/W at 1000~3000$cd/m^2$ respectively and the maximum luminance was about 80,000 $cd/m^2$.

• 한국전자통신학회논문지
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• 제7권6호
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• pp.1513-1518
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• 2012

본 논문에서는 PC모듈 기반으로 LED(Light Emitting Diode)의 White조명을 이용한 VLC(Visible Light Communication) 송 수신기 모듈의 미디어 전송 시스템을 구현하고 전송 기술에 대해 성능 분석을 하기 위한 연구이다. LED가시광통신을 실현시키고자 송신부에는 1~12개의 LED발광소자와 수신부에는 가변 센서를 사용 하고자 한다. LED가시광통신을 하고자 개발이 이루어진 송 수신부의 초기 거리 값은 0~1m이상으로 하고 전체 시스템 전송 속도는 수천 kbps를 가지는 가시광 미디어 전송 시스템을 이루었다. 성능 분석을 위해서, PC 모듈에 LED 및 적외선센서를 구성하여 예측 및 통신 거리에 분석하여 응용 방법과 가능성에 대해서 확인하고자 한다. LED 모듈의 전체적인 효율 증가를 위하여 렌즈 착용시와 미착용시 각 성능을 측정하여 약 20%의 효율이 증가하였음을 알 수 있었다.

• 한국재료학회지
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• 제21권6호
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• pp.295-298
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• 2011

ZnS:Mn, Dy yellow phosphors for White Light Emitting Diode were synthesized by a solid state reaction method using ZnS, $MnSO_4{\cdot}5H_2O$, S and $DyCl_3{\cdot}6H_2O$ powders as starting materials. The mixed powder was sintered at $1000^{\circ}C$ for 4 h in an air atmosphere. The photoluminescence of the ZnS:Mn, Dy phosphors showed spectra extending from 480 to 700 nm, peaking at 580 nm. The photoluminescence of 580 nm in the ZnS:Mn, Dy phosphors was associated with $^4T_1{\rightarrow}^6A_1$ transition of $Mn^{2+}$ ions. The highest photoluminescence intensity of the ZnS:Mn, Dy phosphors under 450 nm excitation was observed at 4 mol% Dy doping. The enhanced photoluminescence intensity of the ZnS:Mn, Dy phosphors was explained by energy transfer from $Dy^{3+}$ to $Mn^{2+}$. The CIE coordinate of the 4 mol% Dy doped ZnS:Mn, Dy was X = 0.5221, Y = 0.4763. The optimum mixing conditions for White Light Emitting Diode was obtained at the ratio of epoxy : yellow phosphor = 1:2 form CIE coordinate.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1002-1005
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• 2006

In this study, we fabricated white organic light emitting devices (WOLEDs) to use single emission layer, DPVBi with partially doped Rubrene. To realize white color, rubrene with 3.6% was partially doped with the gap from interface between DPVBi and hole transport layer NPD in a definite DPVBi layer. As the gap was increased, the intensity of orange peak grows less and less. The WOLED with gap of $5\;{\AA}$ has the best color stability and its color coordination is (0.345, 0.321) at 6V.