• The KIPS Transactions:PartB
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• v.13B no.4 s.107
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• pp.471-478
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• 2006

In this paper, two color contrast evaluation algorithms, W3C and NSSC algorithms are compared and investigated to select proper criteria of the color contrast of text-background color combinations in web documents. The relationship between the color contrast defined by existing formula and the readability rating is not perfect and there is quite a bit of variance, in particular, there is some substantial outlier. I modify the NSSC algorithm to apply all colors and compare the two algorithms to apply same color combinations of web safe colors. A new algorithm considering color temperature feeling as a component of the color contrast is proposed and implemented. As the results of this study, the existing two algorithms are not contradictory to each other, 82% of all color combinations of web safe colors are not proper combinations according to W3C guide which provide severe restriction to select colors in web documents compared to NSSC algorithm. Experimental test shows proposed algorithm is superior to the W3C algorithm with respect to the linearity of relationship between color contrast and readability rating. It means a color temperature feeling is an effective component of a color contrast. But to determine best contribution ratio of the color temperature feeling, further study is required and it is related to Hangul font style and size. The more popular a mobile color display is used, the more important accessibility factor a color contrast will be.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.518-524
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• 2020

This study conducted basic research on an LED lighting design to improve the learning effect from brain wave analysis. The ideal environments of mathematics, language, and creative region can be different. Inside the space where the lighting environment can be experienced directly, the test subject consisted of common elements. Other lighting was blocked completely in controlled lighting conditions. The brain waves were analyzed according to the change in color temperature and illumination. The analyzer used was fabricated by EMOTIV Company. In the variable RGB LED light, the color of the light was measured, and the brain wave of each subject was determined. LED lights have variable color temperature (3000 [K], 4500 [K]. 250 [lux], 70% -350 [lux], 100% -500 [lux]). As research results, the highest concentration in a mathematics study was in the general condition of a high color temperature, in which the optimal condition was a 6000[K] color temperature and 350[lux] illumination. The optimal condition for a language study was a 4500[K] color temperature and 500[lux] illumination, and that of the creative study was 3000[K] color temperature and 500[lux] illumination. Overall, the possibility of emotional ability and concentrated learning efficiency can be improved by the LED lighting design with the color temperature and illumination.

• Journal of Korea Multimedia Society
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• v.9 no.4
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• pp.451-459
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• 2006

Color reproduction of small LCD display is quite different from that of standard CRT due to the difference of physical, electrical, and optical characteristics. In this paper, we propose a simple and practical method using gamma and CCT correction for improvement of color reproduction on a small LCD display. First, we investigate characteristics of a small LCD display such as brightness, uniformity, color temperature, white and black balance, and nonlinear gamma. And, we also analyze color reproduction region and CCT trajectory according to LCD's input levels. Finally, the optimum gamma and CCT compensation method using LUT is proposed, and our proposed method was realized at mobile phone without hardware modification. In the experimental results, the result image of proposed algorithm is more close to standard color.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.186-189
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• 2001

본 연구에서는 2종류의 색온도(4000 K, 2700 K)조건 하에서 작업자의 피로도를 평가하기 위하여 피험자에게 검색작업을 부가하고 주관평가 및 생리신호를 측정하였다. 주관평가는 ME(Magnitude Estimation)법의 설문지를 사용했으며, 생리신호는 ECG, 맥파, 피부전도도, 피부온도, 호흡, 뇌파를 측정하여 그중 ECG신호를 분석하였다. ECG신호 파라미터로서 IBI, BPM, 평균 BPM, LF/HF, CSI, CVI, CV-RR를 분석한 결과, 특히 CSI, CVI, CV-RR가 피로도와 상관관계가 높았다.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.850-853
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• 2011

상대적으로 산출양이 많은 보석용 천연 갈색 다이아몬드는 고온고압 공정을 통해서 칼라센터를 제어하여 색향상이 가능하다. 질소가 불순물로 함유된 Type IaA 다이아몬드를 5.6GPa-30min 조건으로 압력과 처리시간을 고정하고, 이때 처리온도를 1600, 1650, 1750, $1800^{\circ}C$로 바꾸어 HPHT 처리하였다. 처리조건에 따른 다이아몬드의 물성변화 확인을 위해서 광학현미경, FTIR, 저온 PL, Micro-Raman 분석을 진행하였다. 광학현미경 확대 이미지를 통해서, $1600^{\circ}C$에서도 색향상이 가능하였으며 온도증가에 따라 색향상은 진한노랑(vivid yellow)에서 연두 노랑색(vivid greenish yellow)로 색이 변하는 경향이 있었다. 또한 $1750^{\circ}C$의 고온에서는 탄소점으로 추정되는 결함이 확인되었다. FTIR 분석결과에 의해 HPHT 처리 후에도 다이아몬드의 Type IaA로 유지됨을 알 수 있었다. 저온 PL 스펙트럼결과 처리 후 모든 시편에서 H4센터는 소멸하지만 H3 센터는 잔류함을 확인하였다. 따라서 HPHT 처리온도를 조절하여 목표하는 색으로의 향상이 가능하였고, 되도록이면 탄소점과 같은 결함을 방지할 수 있는 저온 HPHT 처리가 유리하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1288-1291
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• 2012

주거공간 내 조명환경은 인간의 심리적, 생리적 기능에 많은 영향을 주는 요소임에도 불구하고 현재의 조명환경은 사용자의 상황과 공간 특성을 고려하지 않은 단일화된 형태로 제공하고 있다. 또한 인간의 심리에 영향을 미치는 조명의 요소로는 빛의 색온도, 조도, 색상, 눈부심, 균제도 등이 있으나 대다수의 조명은 밝은 조도에만 초점을 맞추어 사람의 눈부심을 자극하는 조명이 대부분을 차지하고 있다. 따라서 사용자에게 좀 더 편안하고 쾌적한 조명환경을 제공하기 위해서는 사용자의 행동, 심리적 상황 등에 따라 조명의 색온도, 조도 그리고 색상이 고려된 상황조명 서비스가 필요하다. 본 논문에서는 사용자의 재실여부와 행위 등의 상황을 인지하고 이에 따라 조명의 On/Off, 색온도, 조도, 색상의 조명환경을 제공하는 상황인지 기반의 LED 조명 제어시스템을 제안한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.10-22
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• 2009

This paper presents an LED lighting system with an LED color control algorithm that can independently change its color temperature and illuminance. To show the validity of the proposed algorithm, it is proven that its solution always exists. The proposed algorithm was applied to the control of an LED module that is composed of red, green, blue, and white (RGBW) LEDs. Its color temperature variation ranged from 3,500~7,500[$^{\circ}K$], and its illuminance ranges from 500~1,500[lux]. Within these range, the color temperature and illuminance deviations are as low as $\pm0.8$[%] when the junction temperature of LEDs are maintained at 40[$^{\circ}C$]. In the range of 30~70[$^{\circ}C$], the measured illuminance and color temperature deviations are as low as 2.1[%] and 3.6[%], and the compensated ones are as low as 1[%] and 0.49[%], when the desired illuminance and color temperature are 1,000[lux] and 6,500[$^{\circ}K$], respectively.nyang.ac.kr).

• Journal of Digital Convergence
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• v.11 no.4
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• pp.229-234
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• 2013

The purpose of this study is to develop a lighting apparatus of the illuminance and color temperature to maximize the ability of the optimal combination of light sources that can be controlled efficiently control device. Finding people comfortable feeling for indoor lighting that can be used in a variety of color temperature illumination area by combining light sensitivity can be realized. Lighting apparatus for fluorescent lamps with different color temperature of 2000K and 8000K, and by varying the quantity of each of the fluorescent lamps, the illuminance of lighting equipment and color temperature through optical simulations were evaluated. By infrared remote control receiver, divided into 5 types of relaxation, conversation, meeting, hospitality, arts and the lighting environment you want to transfer the PC0 ~ PC4 through the parallel port on the mode selected by the user at the receiving end the DC voltage output. EEFL inverter input DC voltage and the DC input voltage, depending on the level of EEFL dimming value (illuminance and color temperature) lighting environment you want to create change while using a PIR sensor EEFL automatically turn off if people do not have was developed so that the power consumption so you can save.

• Korean Journal of Optics and Photonics
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• v.25 no.2
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• pp.102-107
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• 2014

In this paper the spectra of correlated color temperature (CCT) tunable white light-emitting diode (LED) luminaires, consisting of commercial red, green, blue, and amber LED chips, were optimized to increase color rendering index (CRI), and a special CRI of R9 for deep red color was obtained. To improve the design's accuracy, measured LED spectra were used instead of mathematically modeled ones. Real CCT tunable LED luminaires with CRIs of 87-90 and R9s of 34-93 were fabricated and demonstrated at CCTs of 3000-6000 K.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.194-201
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• 2005

도시에서의 빛의 연출은 도시의 축을 부각시키고, 가로의 아이덴티티를 연출함으로서 도시의 인지도를 향상시킬 수 있다. 또한 야간의 경관은 인공조명을 이용한 빛의 연출로 주간과는 다른 빛환경 경관을 연출할 수 있다. 이에 본 연구는 도시 가로 중에서 상업가로와 주거가로를 대상으로 주 야간의 빛환경 특성을 분석하여, 가로의 용도에 따른 주야간의 빛환경 차이를 고찰하였다. 이를 위하여 두 가로의 일정길이에 대하여 수평면조도, 스칼라 조도, 휘도 및 색온도를 측정하였으며 측정결과를 용도별, 주 야별로 비교하여 분석하였다. 측정한 결과를 정리하면 다음과 같다. (1)수평면조도의 측정 결과, 주간의 주거가로에 비하여 상업가로가 28.8[%] 높게 나타났으며 야간의 경우 87.2[%] 높게 나타났다. (2) 스칼라조도의 측정결과, 스칼라조도의 특성상 전반적으로 균일한 분포를 보이며, 수평면 조도와 마찬가지로 주간에 비하여 야간에 84[%] 높은 값이 측정되었다. (3) 휘도의 측정 결과, 주간 배경에 대한 대상의 휘도비는 상업과 주거가로가 1:2이하로 나타나 조화로운 가로경관을 연출하며, 야간배경에 대한 대상의 휘도비는 상업가로는 1:17로 활기 있는 경관을 연출하고 주거가로는 1:5로 가로경관 이미지에 적당한 강조효과가 나타났다. (4) 색온도의 측정 결과, 주간의 배경은 맑은 하늘의 색온도를 나타냈으며 대상은 상쾌하고 활동적인 이미지의 색온도를 나타내었다. 또한 야간의 경우 상업가로와 주거가로 모두 나트륨 등의 영향을 받아 전반적으로 따뜻한 느낌의 색온도가 연출되었다.