• KIEAE Journal
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• v.12 no.3
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• pp.101-106
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• 2012

Lighting energy accounts for approximately 20% of the electrical energy used worldwide. Thus, High efficiency Light emitting diode(LED)lighting is getting more popular as the next generation lighting replaced to traditional lighting fixtures. Also, LED lighting not only has a long lifetime but also can realize a variety visual environments through the wavelengh control. The lighting energy varies depending on the Spectral Power Distribution(SPD) even though the Illuminance level is same. Therefore, This study indicates that the difference of indoor energy consumption under the same illuminance level when Spectral Power Distribution(SPD) is different. As a result, Lighting energy consumption under red-color emphasizing SPD is about 10% lower than under blue-color emphasizing SPDs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.7-17
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• 2015

Changes in melatonin concentration levels by differences in CCT of white LED light focused on Spectral Power Distribution (SPD) differences compared to the same CCT of conventional fluorescent light were analyzed. For this, melatonin concentration levels in saliva samples were taken over four different experiments at seven-day intervals. In 71.4% of participants, it was confirmed that melatonin concentration is suppressed by exposure to light, and a slight difference was observed by different CCTs. In addition, Experiment II with a high CCT was relatively high in terms of the melatonin suppression rate compared to Experiment III. A key finding was the possibility that different SPDs under a particular CCT of white LED light compared to the same CCT of conventional fluorescent light could have the same effect on the melatonin suppression.

• Journal of Internet Computing and Services
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• v.24 no.2
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• pp.19-26
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• 2023

Humans have adapted and evolved to natural light. However, as humans stay in indoor longer in modern times, the problem of biorhythm disturbance has been induced. To solve this problem, research is being conducted on lighting that reproduces the correlated color temperature(CCT) of natural light that varies from sunrise to sunset. In order to reproduce the CCT of natural light, multiple LED light sources with different CCTs are used to produce lighting, and then a control index DB is constructed by measuring and collecting the light characteristics of the combination of input currents for each light source in hundreds to thousands of steps, and then using it to control the lighting through the light characteristic matching method. The problem with this control method is that the more detailed the steps of the combination of input currents, the more time and economic costs are incurred. In this paper, an LED lighting control method that applies interpolation and combination calculation based on the minimum spectral power distribution information for each light source is proposed to reproduce the CCT of natural light. First, five minimum SPD information for each channel was measured and collected for the LED lighting, which consisted of light source channels with different CCTs and implemented input current control function of a 256-steps for each channel. Interpolation calculation was performed to generate SPD of 256 steps for each channel for the minimum SPD information, and SPD for all control combinations of LED lighting was generated through combination calculation of SPD for each channel. Illuminance and CCT were calculated through the generated SPD, a control index DB was constructed, and the CCT of natural light was reproduced through a matching technique. In the performance evaluation, the CCT for natural light was provided within the range of an average error rate of 0.18% while meeting the recommended indoor illumination standard.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.168-173
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• 2011

Recently, from a saving energy and environmental lighting sources point of view, using LED lighting have been increased rapidly. The colors of light was applied to the control of dimmers that is composed of red, green, blue, and white(RGBW) to improve the quality of visual environment. Moreover this study has been processed to develop adjustable dynamic LED lighting system on SPD and definitize the various spectral power distribution and color temperature of light through the control of the four dimmers. It is possible to combine up to $432^4$ kinds of light. Measurement of illuminance of range on working surface was as 7~l,831 lux. Application of visual environment for occupants can be expected according to control of lighting performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3207-3213
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• 2011

Most methods of color constancy, which is the ability to determine the object color regardless of the scene illuminant, have failed to meet our expectation of their performance especially about low-illuminated scenes. Some methods with high performance need to be developed, but we must, above all else, obtain experimental images for analyzing the required circumstances or evaluating the methods. Therefore, the paper produces new sets of images so that they can be used in the development of color constancy methods suitable for low-illuminated scenes. These sets are composed of two parts: one part of images which are synthesized with spectral power distribution(SPD) of illuminants, spectral reflectance curve of reflectances, and sensor response functions of camera; the other part of images where the intensity of each image is adjusted at the uniform rate. In an experiment, the use of the sets takes an advantage that its result images are analyzed and evaluated quantitatively as their ground truth data are known in advance.

• Textile Coloration and Finishing
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• v.13 no.6
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• pp.397-404
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• 2001

The accurate representation of the colors of dyed fabric on a color CRT(cathode ray tube) screen is the basis for the automatic process in dyeing industry. In the former study, we had focused on the theoretically color matching method between CIE(International Commission on illumination) and RGB color coordinates, but In this study we tried simulating the colors obtained from fabrics on the color CRT by using experimental method. we obtained the following results. 1. We could simulate all of the color CRT by gamut mapping method, even though some of the KOSCOTE(Korea Standard Color of Textile) colors represented on the color CRT didn't exist in the region of color region 2. We could do conditional matching by CIE system, even though it was hard to do invariant matching the Red, Green, Blue phosphors of the color CRT because of the SPD(Spectral Power Distribution) which had been set up before. 3. We could simulate all the colors obtained from fabrics on the color CRT by matching those two color groups from KOSCOTE fabrics and color CRT using match algorithm and matching programs. 4. If we get over on obstacles by grafting CCM and CCK machines which have been used in educational and industrial areas by matching KOSCOTE with color CRT we will be able to invent color simulation system controled automatically.

• Textile Coloration and Finishing
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• v.13 no.6
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• pp.39-39
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• 2001

The accurate representation of the colors of dyed fabric on a color CRT(cathode ray tube) screen is the basis for the automatic process in dyeing industry. In the former study, we had focused on the theoretically color matching method between CIE(International Commission on Illumination) and RGB color coordinates, but In this study we tried simulating the colors obtained from fabrics on the color CRT by using experimental method. we obtained the following results. 1. We could simulate all of the color CRT by gamut mapping method, even though some of the KOSCOTE(Korea Standard Color of Textile) colors represented on the color CRT didn′t exist in the region of color region. 2. We could do conditional matching by CIE system, even though it was hard to do invariant matching the Red, Green, Blue phosphers of the color CRT because of the SPD(Spectral Power Distribution) which had been set up before. 3. We could simulate all the colors obtained from fabrics on the color CRT by matching those two color groups from KOSCOTE fabrics and color CRT using match algorithm and matching programs. 4. If we get over on obstacles by grafting CCM and CCK machines which have been used in educational and industrial areas by matching KOSCOTE with color CRT we will be able to invent color simulation system controled automatically.