• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.872-875
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• 2002

This paper presents an efficient method of estimating the correlated color temperature of an input color image and of generating a converted color image that can approximate the new target color temperature. After extracting the potential reference white region for an uncalibrated color image and estimating its correlated color temperature, the color conversion method produces a new color image with a target color temperature. Speed improvement and memory reduction have been achieved by using a simple transfer method without involving the CIE XYZ conversion step.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.1-14
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• 2014

This study has found out appropriate scopes of correlated color temperature and illuminance value with regard to general diffused lighting and work in the kitchen. It also has presented appropriate photometric quantity control speed for behavioral change with the following results. 1)For general diffused lighting, the appropriate photometric quantity has turned out to be 4,000 to 4,500K in color temperature and illuminance value of 300 to 400lx. And 300lx at 4,500K has proven to be the most comfortable, behavior-appropriate, and preferred pair. 2)As far as appropriate photometric quantity for work is concerned, color temperature of 4,000 to 5,000K and illuminance value of 600 to 800lx are appropriate, while 700lx at 4,500 to 5,000K are the most comfortable, behavior-appropriate, and preferred set. 3)As for appropriate photometric quantity control speed in behavioral change, 3 to 5 seconds has proven the most comfortable, appropriate, and preferred for behavioral change from entry to general areas and 1 to 3 seconds for change from general to work.

• KIEAE Journal
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• v.8 no.6
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• pp.21-26
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• 2008

According to the tendency of energy efficiency and environment-friendly chracteristics, demend of High-efficiency lighting using LED(Light Emitting Diode)are being increased actively and applied in various fields. However, In order to adequate application of LED light sources, it is necessary to lighting environment and luminous characteristics of LED light sources. This Study aims to characterize the work-plane lighting environment by LED light sources comparing with fluorescent light sources which are widely used. For the sake of this study, a fluorescent light source and 5 LED light sources were introduced and luminance and correlated color temperature were measured to evaluate luminance contrast. The experimental model is Mock-up which is $4.9m{\times}7.2m$ with a height of 2.9m. The test room was set up partition and desks. Luminance and correlated color temperature were measured work-plane on the desk which was set up local lighting by the Radiant Imaging ProMetric 1400. The optical characteristics data of LED can give a lot of advantages to design LED lighting appliances. Hereafter, the object of research will be conducted to evaluate effects of LED light sources on working performance, survey of visual performance, preference and physiology of subjects.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.961-965
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• 2006

White organic LED spectrum for lighting and displaying should be designed for high luminous efficiency as well as good chromaticity coordinate, pleasant correlated color temperature and color rendering. A program based on Matlab was made to make these calculations convenient. The chromaticity coordinate and luminous efficiency was calculated according to the CIE 1931 colorimetric system, while the correlated color temperature(CCT) was calculated based on CIE 1960 UCS diagram. The color rendering characteristics were evaluated according to the CIE Color Rendering Index (CRI), using Ra, Ri and ${\bigtriangleup}E$ from the 14 color samples defined in CIE13.3.

• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.110-117
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• 2009

This work introduces the uncertainty evaluation formulation on color measurement of light sources and display devices, such as CIE 1931 (x, y) chromaticity, CIE 1960 (u, v) chromaticity, correlated color temperature, and distribution temperature. All the mentioned quantities are reduced from spectral data in the visible range, for which uncertainties are strongly correlated between different wavelengths. Using matrix algebra we have formulated the uncertainty propagation from the SI- traceable spectral irradiance standard to the individual color related measurement quantities taking the correlation between wavelengths into account. As a result, we have demonstrated uncertainty evaluation examples of 3 types of light sources: CIE illuminant A, LED white light, and LCD white light. This method can be applied to any other quantities based on spectral measurement such as solar irradiance, material color measurement, etc.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.1
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• pp.99-106
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• 2019

This study aims to recommend the proper Color rendering index (CRI), the Correlated Color Temperature (CCT), and illuminance levels of Light-Emitting Diode (LED) lighting based on the analysis of the criteria of the current CRI, the CCT, and illuminance levels in merchandising spaces with LED lighting conditions. It would be a basic material to apply in line with user preference for LED merchandising lighting. To this end, it examines relevant literature review on the experiments designed to test whether lighting characteristics affect brightness perception, color appearance, and pleasantness. Highly saturated colors appear brighter than low saturated colors. Two lighting applications - grocery and clothing shop - were created in elaborating the effect of LED lighting characteristics of CRI on color appearance and the CCT and illuminance on pleasantness. The findings show that the criteria of CIE Ra<80 are appropriate to provide better color appearance of illuminated products in terms of LED lighting that can enhance color saturation, particularly for the red color. Furthermore, 2700 K and less than 500 lux for grocery, 4000 K and more than 500 lux for clothing shop are found to be the proper the CCT and illuminance levels respectively to bring better preference under LED lighting.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.15-21
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• 2004

The optical characteristics; luminous flux, correlated color temperature, and CIE -chromaticity coordinate etc., of HB LED(high brightness light emitting diode) of yellow/green/white SMD(surface mounted device) type were tested with integrating sphere photometer and monochromator, and the results were comparatively evaluated And, for the white LED, color rendering indices were considered to analyze.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.14-26
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• 2015

This study has been conducted so as to analyse user's sensibility on lighting method, correlated color temperature and illumination by composing surface light source, which was projected onto a unit side of interior wall, ceiling and floor. 1) As an analyzed results of the sensibility images, it showed that the "snug & tender" value had got higher when the correlated color temperature got lower. And the "energetic, cheerful" value had got higher when the level of illuminance got lower. Furthermore, the "unusual, unique" showed higher value on the illuminated floor circumstance. Finally, the higher correlated color temperature had been, "energetic, cheerful" value also got higher. 2) As a result of multi-regression analysis, it was found that 3000K and 100lx had the biggest influence on 'snug' image while 5,500K, 500lx had the biggest influence on 'energetic' image. In addition, it was found that the illuminated floor had a big influence on 'unusual' image while 500lx had the biggest influence on 'refined' image.

• Food Engineering Progress
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• v.15 no.1
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• pp.85-89
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• 2011

Freeze-dried Ecklonia cava powder was incorporated into cookie dough at 5 levels (0%, 1.5%, 3%, 4.5%, and 6%, w/w) by replacing equivalent amount of wheat flour of the cookie dough. After aging and sheeting, cookies were baked at $185^{\circ}C$ for 14 min in a convection oven. The baked cookies were cooled to room temperature for 30 min and packed in airtight bags prior to all measurements. Lightness $(L^*)$ decreased significantly as the E. cava powder content increased (p<0.05) and a decreasing trend in both redness ($a^*$-value) and yellowness ($b^*$-value) was observed. On the other hand, firmness increased significantly with an increase in E. cava powder content (p<0.05). Increases in E. cava powder concentration up to 6% in the cookie formulation significantly increased the intensities of all sensory attributes such as color, flavor, taste, and firmness (p<0.05). Correlation analysis indicated that the E. cava concentration correlated significantly with most of the properties except for $a^*$-value (p<0.01, 0.05, or 0.001). Properties such as firmness and sensory color and firmness correlated positively while $L^*$- and $b^*$-value correlated negatively with E. cava concentration. Sensory color correlated negatively with $L^*$- and $b^*$-value. Sensory firmness correlated positively with mechanically measured firmness.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.449-456
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• 2012

For two well-known modulation methods, stepwise current modulation (SCM) and pulse width modulation (PWM), the effects of driving current modulation conditions on chromaticity were experimentally investigated in a white LED lighting system. For the experimental implementation of both SCM and PWM, a white LED lighting was fabricated using phosphor converted (PC) white light emitting diodes (LEDs) and a driving circuit module was developed. By using them, the variations of illuminance, color coordinates, and spectrum were evaluated under various forward current conditions. Through the analysis in color coordinates, yellow shift in SCM and blue shift in PWM were observed on chromaticity diagrams with increasing average driving current. In addition, in order to analyze color deviation quantitatively, color distance before and after current increase, and the correlated color temperature (CCT) were calculated. As a result, for the white LED lighting in both modulation conditions, the maximum difference in the calculated CCT was obtained close to 1000 K. It means that careful consideration is required to be taken in the design of illumination systems to avoid serious problems such industrial accidents.