• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.37-41
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• 2018

$Y_3A_{l5}O_{12}:Ce^{3+},Pr^{3+}$ single crystal phosphor was prepared by floating zone method. single crystal was confirmed to have a Ia-3d (230) space group of cubic structure and showed regular morphology. The optical properties, single crystal exhibited a emission band from green, yellow wide wavelength and 610nm, 640nm red wavelength vicinity. The luminance maintenance rate was decreased by phonon with increasing temperature, but high luminance is maintained more than powder phosphor. In addition, $Y_3A_{l5}O_{12}:Ce^{3+},Pr^{3+}$ single crystal phosphor was applied to a high power blue laser diode, we implemented high power white laser lightings. and it was confirmed that thermal properties over time, due to the effective heat transfer of complete crystal structure. We confirmed that excellent radiant heat properties than powder phosphor was applied to a high power white laser diode.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.205-206
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• 2005

태양 전지를 이용하여 정원등의 시스템을 구성하면 환경 친화적이면서도 에너지 절감의 큰 효과를 얻을 수 있다. 또한 기존의 정원등은 수은등을 사용하기 때문에 전력 소비가 많은 반면, 고휘도 LED를 사용한 정원등은 전력소비를 줄일 수 있는 큰 장점을 가지고 있다. 본 논문에서는 간단한 회로 구성과 CDS센서를 이용하여 실제적인 회로 설계를 하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.137-140
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• 2008

실내조명으로서의 LED는 휘도의 분포특성이 기존의 조명기구와는 판이하게 다르며, 이에 따라 불쾌감을 느끼는 정도에서도 변화가 일어날 수 있다. 본 연구에서는 현재 가장 일반적으로 사용되어지는 글레어 평가지수인 UGR을 간단히 보정하여 LED 조명기구에 대한 값으로 사용할 수 있도록 주관평가 실험을 통해 보정식을 산출해내고 LED 조명기구별 증가계수 k를 구하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.13-20
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• 2010

Until now, dimmable fluorescent luminaires has been widely used for dimming systems, and LED is currently attracting attentions as a alternative lamp due to environmental problem issues. LED, one of eco-friendly high efficiency lamp, has advantage that dimming is easy than fluorescent luminaire. But there have been not enough research on technical development and application for LED dimming. Therefore, to analyze luminous quantity of dimmable LED, the illuminance, color temperature, luminance, and current were measured in the whole range of dimming. In the results of this study, the dimmable LED of various types showed a similar trend in the changed luminous quantity by dimming.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2221-2226
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• 2009

This paper presents the design of the LED sign board system installed on the exterior of a building and powered by a photovoltaic system. A grid connected photovoltaic system has been designed with the capacity estimate of the load, battery and power. After the luminance and uniformity of LED load has been checked, the sign board and the solar cell modules have been installed. The performance and problems occurred during the field test for the photovoltaic LED sign board system have been analyzed.

• The Journal of the Korea Contents Association
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• v.15 no.8
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• pp.69-76
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• 2015

With Various signs are installed at roadside to display the message which rather confuse the drivers. The technologies using advanced lighting system and LED have improved the visibility at nighttime but the problems with plural signs have yet to be resolved. In order to solve this problem, LED and the prismatic variable message sign have been applied. But, they have been provided limited information by the display limit. This research conducted to study patent and technical trend of the existing variable message signs to understand the present technology. And, we suggested next generation display to improve providing information. Therefore, we conducted to compare the LED and the OLED by technical and economical literature review. Also, this research conducted test of luminance contrast about the LED and the OLED display in order to understand the possibility of replacing road signs.

• Journal of the Optical Society of Korea
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• v.19 no.2
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• pp.159-164
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• 2015

In the injection-molded light guide plate the replication quality, i.e. the reproduction accuracy, of micro-patterns should be high and uniform over the entire surface area. However technical difficulty in meeting the necessary replication quality arises as the plate size becomes large for TV applications. We propose a simulation technique to optimize the distribution of micro-patterns on a 55-inch injection molded light guide plate considering non-ideal replication quality of micro-patterns. The luminance uniformity could be improved by more than 16% by optimizing the pattern distribution in spite of the same replication quality.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.223-231
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• 2015

LEDs have been widely used in lighting displays, automobiles, and airplanes owing to their excellent light output characteristics and long lifespan. Though LEDs are manufactured under the same process, variations in impurity concentrations cause electrical deviation among LEDs. The resulting electrical deviation can not only reduce the life time of the LED but also cause non-uniform luminance of LEDs connected in parallel. LED driving circuit is required to solve these problems. In this paper, we propose a LED driving system using Y-type current balancing transformer to maximize the efficiency of the system by removing output stage Schottky diodes. Experimental results are presented to verify the performance of proposed LED driving system that is applied to 80 W LED modules.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.66-75
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• 2010

We proposed an occupant sensing system using single video camera and ultrasonic sensor for the advanced airbag. To detect the occupant form and the face position in real-time, we used the skin color and motion information. We made the candidate face block image using the threshold value of the color difference signal corresponding to skin color and difference value of current image and previous image of luminance signal to gel motion information. And then it detects the face by the morphology and the labeling. In case of night without color and luminance information, it detects the face by using the threshold value of the luminance signal get by infra-red LED instead of the color difference signal. To evaluate the performance of the proposed occupant detection system, it performed various experiments through the setting of the IEEE camera, ultrasonic sensor, and infra-red LED in vehicle jig.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1401-1404
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• 2008

Temperature Compensation Method of Local Dimming LED Backlight System is proposed. The luminance levels of the LED backlight are not stable over temperature and time due to the inherent characteristics of the LED. The characteristics of LED backlight are investigated and a temperature compensation method is presented. The image distortion caused by temperature variation of LED block can be effectively compensated by the proposed temperature compensation method.