• Transactions on Electrical and Electronic Materials
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• 제3권1호
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• pp.38-41
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• 2002

We have investigated current-voltage-luminance characteristics of organic light-emitting diodes based on TPD/Alq$_3$organics depending on the application of forward-backward bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the current-voltage characteristics were measured. We have observed that the current-voltage characteristics shows a reversible current maxima at low voltage, which is possibly not related to the emission from Alq$_3$. Current-voltage-luminance characteristics imply that the conduction luminance mechanism at low voltage is different from that of high voltage one.

• 한국지능시스템학회논문지
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• 제24권4호
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• pp.424-429
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• 2014

본 논문에서는 발광광고물의 휘도를 측정하는 영상기반 휘도측정시스템을 제안한다. 제안하는 휘도측정시스템은 DSLR 카메라의 영상을 이용하여 점휘도계의 효율성과 면휘도계의 휴대성 및 경제성의 단점을 보완하며, 대상의 전체적인 휘도를 측정하는 시스템으로 영상을 입력받아 휘도분석 알고리즘을 통해 실시간으로 휘도값이 출력되도록 설계하였다. 측정 대상인 발광광고물은 설치 위치, 크기, 모양이 다양하며, 발광광고물의 휘도는 측정 거리, 각도, 색 등 다양한 조건에 따라 측정값이 달라진다. 따라서 정확한 휘도를 측정하기 위하여 측정대상물과의 거리에 따른 휘도값의 변화를 측정하였고, 측정 거리가 증가하면 휘도값이 변화하는 것을 고찰하였다. 실험을 통하여 측정 위치와 휘도값의 연관성을 수식으로 나타내었고, 제안한 방법을 평가하기 위해 점휘도계를 이용한 측정값과 비교 실험을 진행하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1491-1492
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• 2011

In this study, we investigated about the effect of hole transport layer materials(${\alpha}$-NPD, TPD) depending on the electrical properties of organic light emitting diode. In deposition method, we used thermal evaporation and it was a method for performing thin film by attaching vaporizing a molecule to substrate in a high thermal and vaccum. We analyzed luminance, current density, external quantum efficiency and current efficiency in 40 [nm] as optimization thickness of ${\alpha}$-NPD and TPD. In result of experiment, maximum luminance of TPD had 1.1 times higher than ${\alpha}$-NPD, but ${\alpha}$-NPD had luminance, external quantum efficiency, and current efficiency higher than TPD in low operating voltage. Actually, ${\alpha}$-NPD had efficiency higher than TPD in low operating voltage.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.60-63
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• 2012

Enhancement of efficiency and luminance of organic light-emitting diodes was investigated by the introduction of a lithium carbonate ($Li_2CO_3$) electron-injection layer. Electron-injection layer is used in organic light-emitting diodes to inject electrons efficiently between a cathode and an organic layer. A device structure of ITO/TPD (40 nm)/$Alq_3$ (60 nm)/$Li_2CO_3$ (x nm)/Al (100 nm) was manufactured by thermal evaporation, where the thickness of $Li_2CO_3$ layer was varied from 0 to 3.3 nm. Current density-luminance-voltage characteristics of the device were measured and analyzed. When the thickness of $Li_2CO_3$ layer is 0.7 nm, the current efficiency and luminance of the device at 8.0 V are improved by a factor of about 18 and 3,000 compared to the ones without the $Li_2CO_3$ layer, respectively. The enhancement of efficiency and luminance of the device with an insertion of $Li_2CO_3$ electron-injection layer is thought to be due to the lowering of an electron barrier height at the interface region between the cathode and the emissive layer. This is judged from an analysis of current density-voltage characteristics with a Fowler-Nordheim tunneling conduction mechanism model. In a study of lifetime of the device that depends on the thickness of $Li_2CO_3$ layer, the optimum thickness of $Li_2CO_3$ layer was obtained to be 1.1 nm. It is thought that an improvement in the lifetime is due to the prevention of moisture and oxygen by $Li_2CO_3$ layer. Thus, from the efficiency and lifetime of the device, we have obtained the optimum thickness of $Li_2CO_3$ layer to be about 1.0 nm.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.727-730
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• 2004

Closed-cell type barrier ribs such as honeycomb, SDR, inverse SDR and waffle types were produced using capillary molding process. Phosphor layers were formed by osmosis coating process on those barrier ribs. Using the rear plate with closed-cell ribs, the luminance and its efficiency was measured. The results demonstrated a significant improvement in efficiency by combining closed-cell type ribs with a new phosphor forming technology

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.227-230
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• 2004

Phosphor layers on rear plate of PDP were formed via osmosis coating process in an attempt to improve thickness uniformity of phosphor layer and eventually to enhance luminance and its efficiency of plasma display panel. The phosphor layers were formed uniformly not only on the sidewalls of barrier ribs but also on the dielectric layer of rear plate by the process. The processing parameters affecting the thickness uniformity of the phosphor layer formed by the osmotic coating process were investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.477-479
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• 2006

In this study, a stripe type counter electrode discharge cell for PDP was attempted to realize high luminance efficiency and low firing voltage for fine pitch discharge cells. The cells were prepared using electroplated Cu/Ni electrodes coated with glass dielectric layer. The discharge behaviors of such cells were observed. These results indicate that the counter electrode discharge cells have different discharge behavior compared with coplanar cells, which may affect the luminance efficiency of the panel.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.53-56
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• 2002

Samsung's newly developed high luminance efficiency 42" VGA plasma display panel is introduced. A new discharge cell structure, SDR (Segmented electrode in Delta color arrayed Rectangular subpixel) has been applied to a full size panel for the first time. In this paper, we describe how this new discharge cell structure for high efficiency is integrated to an energy saving plasma display with better picture quality.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.9-15
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• 2015

Various studies with regard to increasing the optical efficiency of plasmonic color filters have previously been conducted, such as mixing materials or applying diverse pattern shapes. Fundamentally, it is important to maximize the photonic crystal effect by finding the optimum periods of lattice as well as calculating the most efficient transmission area. In this study, we propose a technical method for optimizing the plasmonic color filters that have a high color gamut and luminance by analyzing the light spectrums based on the 1931 color coordinate system. Moreover, we suggest a calculation method in order to define the individual color purity of red and green and blue filters. Consequently, efficiency values are obtained independently from each color filter by evaluating the color purity and the luminance. The final result obtained from simulation are 27.6% of relative luminance and 25.3% of color gamut. The proposed optimization method is applicable to all plasmonic color filters having photonic crystal arrays.

• 한국표면공학회지
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• 제48권4호
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• pp.174-178
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• 2015

We studied emission characteristics for blue fluorescent dual-side emission OLED with Al cathode thickness variation. In the bottom emission OLED of Al cathode with 10, 15, 20, 25, 30, and 150 nm thickness, maximum luminance showed 36.1, 8,130, 9,300, 12,000, 13,000, and $12,890cd/m^2$, and maximum current efficiency showed 2, 8.8, 10, 10.5, 10.8, and 11.4 cd/A, respectively. The emission characteristics of the bottom emission seemed to be improved according to decrease of resistance as the thickness of Al cathode increase. In the top emission OLED of Al cathode with 10, 15, 20, 25, and 30 nm thickness, maximum luminance showed 4.3, 351, 131, 88.6, and $33.2cd/m^2$, and maximum current efficiency showed 0.23, 0.38, 0.21, 0.16, and 0.09 cd/A, respectively. It yielded the highest maximum luminance and maximum current efficiency in Al cathode thickness 15 nm. It showed a tendency to decrease as the thickness of Al cathode increase. The reason for this is due to decrease of transmittance with increasing of Al cathode thickness. The electroluminescent spectra of bottom and top emission OLED were not change.