• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.28-34
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• 2010

The pulse width modulation(PWM) method has been generally used as conventional method controlling luminance of LED(light emitting diode). PWM method as analog method with a relation that duty ratio of LED be proportional to luminance has weak point that it is not compatible with digital method of communication etc. In this paper, a experiment is conducted which the luminance of RGB LED be controlled by digital method. For this, the LED digital control system is developed which consist of LED driving circuits and digital logic circuits. By controlling the number of pluses on RGB LED versus digital input, various lighting colors is implemented and digital codes are optimized in order that measured x, y chromaticity coordinates of lighting colors are comprised in the CIE chromaticity coordinates area of targeted lighting colors. The result of this study can be utilized usefully in research on implementing full color by using remote control of LED lamp with digital communication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.110-112
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• 2011

LED조명장치는 기존 광원의 대체품으로 자동차분야, 특수조명, 디스플레이, 항공등 많은 분야에서 활용이 증가하고 있다. 일반적으로 RGB 멀티칩 LED는 천연색 구현이 가능하여 경관조명 또는 감성 조명용으로 적용되고 고출력 백색 LED는 실내외 일반조명 또는 특수조명용으로 적용되고 있으므로 광효율, 연색지수를 증가하기 위한 연구가 계속 진행 중이다. 본 논문에서는 다양한 마이컴 종류 중 하나인 Cypress사의 PSoC을 이용한 LED 조명의 자연광 구현에 대하여 연구하고자 한다. 이를 위해 사이프레스사의 EZ-Color 모듈을 이용한 다양한 색 구현보다 자연광을 구현하기 위한 색온도 가변에 중점을 두고 연구를 수행하였다. 기존에 제시된 날씨와 계절, 시간에 따른 태양광의 색온도 데이터를 이용하여 다양한 색온도를 나타내기 위한 RGB 색혼합 비율에 대해 연구를 수행하였다. 이 연구를 통해 인간을 위한 감성조명의 개발에 참고할 수 있도록 데이터를 제시하고자 한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.359-364
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• 2011

The study uses department of the sensitivity and fuzzy reasoning, one of artificial intelligence algorithms, so that develop LED lighting system based on fuzzy reasoning for systematical control of the LED color temperature. In the area of sensitivity engineering, by considering the relation between color and emotion expressed as an adjective word, the corresponding sensitivity word can be determined, By taking into consideration the relation between the brain wave measured from the human brain and the color temperature, the preferred lesson subject can be determined. From the decision of the sensitivity word and the lesson subject, we adjust the color temperature of RGB (Red, Green, Blue) LED. In addition, by using the information of the latitude and the longitude from GPS(Global Positioning System), we can calculate the on-line moving altitude of sun. By using the sensor information of both temperature and humidity, we can calculate the discomfort index. By considering the altitude of sun as well as the value of the discomfort index, the illumination of W(white) LED and the color temperature of RGB LED can be determined. The (LED) sensitivity lighting control system is bulit up by considering the sensitivity word, the lesson subject, the altitude of sun, and the discomfort index The developed sensitivity lighting control system leads to more suitable atmosphere and also the enhancement of the efficiency of lesson subjects as well as business affairs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.696-704
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• 2013

In this paper, we introduce the LED emotional lighting system realized with the aid of both intelligent algorithm and RGB LED combined with White LED. Generally, the illumination is known as a design factor to form the living place that affects human's emotion and action in the light- space as well as the purpose to light up the specific space. The LED emotional lighting system that can express emotional atmosphere as well as control the quantity of light is designed by using both RGB LED to form the emotional mood and W LED to get sufficient amount of light. RBFNNs is used as the intelligent algorithm and the network model designed with the aid of LED control parameters (viz. color coordinates (x and y) related to color temperature, and lux as inputs, RGBW current as output) plays an important role to build up the LED emotional lighting system for obtaining appropriate color space. Unlike conventional RBFNNs, Fuzzy C-Means(FCM) clustering method is used to obtain the fitness values of the receptive function, and the connection weights of the consequence part of networks are expressed by polynomial functions. Also, the parameters of RBFNN model are optimized by using PSO(Particle Swarm Optimization). The proposed LED emotional lighting can save the energy by using the LED light source and improve the ability to work as well as to learn by making an adequate mood under diverse surrounding conditions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.198-198
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• 2003

LED(Light Emitting Diode)는 전기 신호를 빛으로 신호를 보내고 받는데 사용되는 반도체의 일종으로 가정용 가전제품, 리모컨, 전광판, 각종 자동화 기기등에 사용된다. 3색광 백색 LED는 soft-UV 또는 blue 빛을 내는 device 와 RGB 형광체로 이루어져 있다. 현재 연구중인 3색광 백색 LED는 InGaN 또는 GaN 이 RGB 형광체를 여기 시키는것이 대부분이다. 이러한 경우에 유기물과 무기물 형과체가 백색광을 구현하기 위해 사용된다. 유기물의 경우에는 lift-time 이 짧고, 무기물의 경우에는 유해원소인 S, Cd등이 포함되기 때문에 환경오염이 야기된다. 이러한 단점을 보완하기 위해 진화 최적방법을 이용하여 alkali earth borosilicate ((Eu,Mg,Ca,Sr,Ba)$_{x}$ $B_{y}$ S $i_{z}$ $O_{d}$ ) 계열에 $^{Eu3+}$을 도핑하여 고효율 형광체를 합성하였다.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2585-2587
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• 2001

This paper suggests a method of color variation technique to generate stable white light. The light from high brightness RGB LED was mixed according to the RGB LED luminance ratio. A microcontroller-based PWM control circuit and switching circuit is used to achieve full color variation. It is confirmed that the stable white light and full color variation is possible.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.2
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• pp.98-104
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• 2003

This paper proposes the design of a multi-color lamp using high brightness RGB LEDs for color variation. Appropriate number of RGB LEDs is so chosen according to the color mixing theory that the overall LEDs represent a color temperature of 6500K. Also, the chosen RGB LEDs are suitably arranged by using an optical design program. The lamp has an internal controller circuit, so it can be directly connected to the existing incandescent lamp socket. It's main body is comprised of two PCB layers. The upper layer contains 44 LEDs and the lower one has a simple microcontroller-based PWM control circuit. The lamp has functions of both ON/OFF control and PWM control, and enables color variation of over 100,000 colors and of more than 10 patterns.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.85-88
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• 2007

A number of R, G and B LEDs for reference color temperature mixing ratio of RGB was determined by the theory of RGB mixing as a baseline. Once the number of LEDs was determined the objective color temperature from baseline has been achieved by the control the RGB duty ratio. And a practical prototype of 50W floodlighting adjusted by the above algorithm. The micro controller was developed with control algorithm for RGB duty ratio to obtain the objective color temperature. Detailed experiments to optimize algorithm of duty ratio and color temperature will be discussed in this paper as well.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.345-349
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• 2014

A direct-lit color-matching liquid crystal display using a lenticular lens array with grouped lens elements that image linear RGB light sources on the RGB subpixels of a color filter to enhance transmittance is designed, simulated, and fabricated. The RGB LED linear light sources were fabricated using small RGB LEDs in a linear array arrangement, and the lenticular lens array consisted of eight units of the same structure with a gap of 2.19 mm. The optical transmittance of the liquid crystal panel was improved by as much as 240% due to the color matching.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.760-769
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• 2016

This paper proposes a hybrid LED driving circuit and its control method for extension of the color gamut of LED. The proposed hybrid LED driving circuit provides the constant current by switching regulation in the high current and by linear regulation in the low current through LED. Furthermore, the magnitudes of the high current and low current were controlled by CC(Continuous Current) control method and PWM(Pulse Width Modulation) control method, respectively. We experimentally confirmed that the current through RGB LED is linearly controlled to 2% maximum current ratio by varying PWM in the proposed driving circuit and control method. As a result of the measurement of the output light color in CIE1976 chromaticity coordinates, we confirmed that the color, which not be expressed by the existing method, uniformly expressed. We confirmed that the color, which can not be expressed by the existing method, was uniformly output and verified that the color gamut was expanded by the low current controlled by the proposed driving circuit and control method.