• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.1-8
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• 2010

Recently, adjustable CCT(Correlated Color Temperature) luminaire for the human circadian rhythm and room atmosphere has been developed. Accurate CCT control is needed in the luminaire for the human circadian rhythm. Therefore, appropriate CCT calculation method for each of fluorescent lamps and white LEDs was examined using three CCT calculation methods in this study. To make accurate CCT combination, CCT for two different CCT lamps was separately measured. And this study compared and analyzed proportionally calculated CCT value with measured value from the compounded luminaire with the two lamps.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.415-419
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• 2010

A phosphor-conversion white light source is demonstrated using an InGaN-based blue laser diode (LD) and a yellow-emitting phosphor excited by the blue LD. The photometric and colorimetric properties of this blue-LD-based white light source are characterized. When injection current of the LD is 100 mA, luminous flux and luminous efficiency of the white light are found to be over 5 lm and 10 lm/W, respectively. When injection current is >90 mA, luminance is estimated to be larger than 10 Mcd/$cm^2$. In addition, color characteristics of the white light such as chromaticity coordinates, a correlated color temperature, and a color rendering index are found to be quite stable as current and temperature of the LD varies. The demonstrated LD-based white light source is expected to be used in high-brightness illumination applications with good color stability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.9-15
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• 2014

An experiment was carried out to evaluate the emotion and sensibility evoked from the different color temperatures(CCT) of electrodeless HID (ELHID) lamp. For this purpose, three ELHID lamps and a metal halide lamp were used as the experimental light sources and thirty Korean adjectives related to the lighting affectiveness were selected for the evaluation. The results showed that ELHID lamps induced different sensibilities according to their color temperature. In particular, 6500 K ELHID was similar to metal halide which has the CCT of 5600 K in the evaluation. Based on the results, we suggested some Korean adjectives and their corresponding English ones which are thought to be suitable for the verbal descriptions of ELHID lamps.

• Korean Journal of Materials Research
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• v.22 no.12
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• pp.669-674
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• 2012

Yellow phosphor dispersed color conversion glasses are promising phosphor materials for white LED applications because of their good thermal durability, chemical stability, and anti-ultraviolet property. Six color conversion glasses were prepared with high Tg and low Tg specimens of glass. Luminous efficacy, luminance, CIE (Commission Internationale de l'Eclairage) chromaticity, CCT (Correlated Color Temperature), and CRI (Color Rendering Index) of the color conversion glasses were analyzed according to the PL spectrum. Color conversion glasses with high Tg glass frit, sintered at higher temperature, showed better luminous properties than did color conversion glasses with low Tg glass frit. The characteristics of the color conversion glass depended on the glass composition rather than on the sintering temperature. The XRD peaks of the YAG phosphor disappeared in the color conversion glass with major components of $B_2O_3$-ZnO-$SiO_2$-CaO and, in the XRD results, new crystalline peaks of $BaSi_2O_5$ appeared in the color conversion glass with major components of $Bi_2O_3$-ZnO-$B_2O_3$-MgO. The characteristics of CIE chromaticity, CCT, and the CRI of low Tg color conversion glasses showed worse color properties than those of high Tg color conversion glasses. However, these color characteristics of low Tg glasses were improved by thickness variation. So color conversion glasses with good characteristics of both luminous and color properties were attained.

• Preventive Nutrition and Food Science
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• v.14 no.1
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• pp.66-70
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• 2009

The effect of baking on the consumer perception and sensory characteristics was investigated using a model system of cookies incorporated with strawberry powder as a value-added food ingredient. Strawberry powder was incorporated into cookie dough at 4 levels (0%, 2%, 4%, and 6%, w/w) by replacing equivalent amount of wheat flour of the cookie dough. After aging and sheeting, cookies were baked at $170^{\circ}C$ for 15 min in an oven. The baked cookies were cooled to room temperature for 1 h and packed in airtight bags prior to all measurements. In terms of color, control received the most favorable mean score, which is significantly higher than others (p<0.05) followed by the 4% sample. The consumer preference on taste and aftertaste was not significantly affected by the amount of strawberry powder incorporated in the formulation (p>0.05). Samples with 4% strawberry powder received the highest mean flavor score of 6.28 which is significantly higher than that of 6% sample (p<0.05). In overall, substitution of 4% strawberry powder in the formulation would result in the most favorable strawberry cookies by the consumers with taking advantages of health benefits of strawberry. Correlation analysis indicated that strawberry powder concentration was significantly correlated positively with sensory color and hardness and negatively correlated with consumers' overall acceptability (p<0.05). Consumers' aftertaste was significantly correlated with overall acceptability which was negatively correlated with sensory hardness (p<0.05). Sensory hardness was highly correlated with sensory color attribute (p<0.05).

• Food Science and Biotechnology
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• v.18 no.4
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• pp.932-938
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• 2009

Browning of tea infusion is an obstructive factor influencing shelf life of ready-to-drink green tea. Effects of temperature and illumination on the browning of green tea infusion were investigated. It was shown that both elevated temperature and illumination led to the browning of green tea infusion, but temperature had greater effect on infusion color and level of catechins than illumination. The levels of unoxidized catechins such as (-)-epigallocatechin gallate (EGCg), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epicatechin (EC), and total catechins remaining in the tea infusion were significantly correlated to color parameters of the tea infusion. Sodium ascorbate inhibited the infusion browning by suppressing the oxidation of tea catechins and it is considered to be a more suitable preservative for prolonging shelf life of ready-to-drink green tea than ascorbic acid because it has less effect on tea taste. The effects of temperature and illumination on the epimerization of catechins were also discussed.

• Journal of Information Display
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• v.12 no.1
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• pp.51-55
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• 2011

Efficient two-color-mixed white organic light-emitting diodes are presented herein by employing a sky-blue phosphorescent dopant of iridium(III)bis[4,6-(difluorophenyl)-pyridinato-N,$C^{2'}$]picolinate (FIrpic) and an orange phosphorescent dopant of bis(2-phenylquinoline)(acetylacetonate)iridium(III) ($Ir(phq)_2$acac) on the emissive layer. Very stable color variation under ${\Delta}$0.02 until a 5000 cd/$m^2$ brightness value was realized by efficient carrier control in a multi-stacked emitting layer of blue/red/blue colors. Maximum current and power efficiencies of 23.8 cd/A and 22.9 lm/W in the forward direction were obtained. With balanced emission from the two emitters, the white-light emission of high correlated color temperature of 7308K and the Commission Internationale de I'Eclairage coordinates of (0.30, 0.33) were achieved.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.22-28
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• 2016

In this study, we fabricated high quality color conversion component with green/red phosphor and low melting glass frit. The color conversion component was prepared by placing the green and red phosphor layer on slide glass via screen printing process. The properties of color conversion component could be controlled by changing coating sequence, layer thickness and heat treatment temperature. We discovered that optical properties of color conversion component were generally determined by the lowest layer. On the other hand, the heat treatment temperature also affected to correlated color temperature (CCT) and color rending index (CRI). The color conversion component with a green (lower) - red (upper) layer which was sintered at $550^{\circ}C$ showed the best optical properties: CCT, CRI and luminance efficacy were 3340 K, 78, and 56.5 lm/w, respectively.

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.124-131
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• 2008

To investigate main air temperature factors correlated to difference of fruit characteristics according to cultivating areas, fruit and air temperature characteristics of eight cultivating areas of 'Fuyu' persimmon were analyzed by principle components and multiple regression analysis. The first principal components extracted from 16 air temperature factors was annual mean temperature, mean temperature during October, annual mean minimum extreme temperature, mean temperature during growing period, and so forth. The second principal components was mean temperature during May and June and so forth. And cumulative contribution was 91.4%. The five of eight cultivating area had clearly the difference of main factors or the correlated direction among cultivating areas. In multiple regression analysis between the extracted main factors and fruit characteristics, fruit hight were highly correlated with mean temperature during growing period ($X_8$) and cumulative temperature ($X_6$), and the regression equation was $Y=150.55-5.375X_8+ 0.014X_6(r^2=0.843)$. Also this regression equation was affected by mean minimum temperature during growing period, cumulative temperature, and mean temperature during August. Fruit diameter was negatively correlated with mean temperature during growing period, flesh browning rate and Hunter a value of peel color were positively correlated with mean minimum temperature during growing period and annual minimum air temperature, respectively.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.335-339
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• 2010

The effects of baking with broccoli powder on the consumer perception and sensory characteristics were investigated using a model system of cookies incorporated with broccoli powder as a value-added food ingredient. Broccoli powder was incorporated into cookie dough at 5 levels (0%, 1%, 2%, 3%, and 4%, w/w) by replacing equivalent amount of wheat flour of the cookie dough. After aging and sheeting, cookies were baked at $170^{\circ}C$ for 8 min in an oven. The baked cookies were cooled to room temperature for 1 hour and packed in airtight bags prior to all measurements. Control received the most favorable mean score, which was not significantly different from samples with 1% broccoli powder for color preference (p>0.05). Results of the consumer preference on taste showed a similar trend. Consumers did not find any significant differences on aftertaste and flavor among samples prepared by replacing wheat flour with up to 2% broccoli powder (p>0.05). Overall, incorporation of 1% broccoli powder in the formulation would result in the most favorable broccoli cookies for the consumers without sacrificing the sensory qualities, while still taking advantages of health benefits of broccoli. Correlation analysis indicated that broccoli powder concentration was significantly negatively correlated with the consumer preference for color, taste, aftertaste, flavor, overall acceptability and positively correlated with sensory color, taste, and flavor (p<0.05). Consumers' color, taste, aftertaste, and flavor were well correlated with the overall acceptability (p<0.05). Sensory intensity results are also presented.