• Journal of Environmental Science International
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• v.33 no.6
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• pp.383-402
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• 2024

Variations in lettuce growth and quality were observed depending on the type of artificial light source. The RGB LED treatment resulted in thick leaf development, leading to higher fresh weight, dry weight, and relative growth rates. Two cultivars, "Tomalin" and "seonpunggold," exhibited increased anthocyanin content and dark red leaf color under conditions of RGB LED treatment. Additionally, they exhibited high chlorophyll content under conditions of RGB LED and RGBFR LED treatments. Particularly, under Red LED treatment, the plants showed elongated leaves with narrow widths, resulting in a higher leaf shape index and a tendency towards leaf curling. Therefore, RGB LED lighting which appropriately blends red, blue, and green lights, is more effective than single lighr sources at improving lettuce growth and quality.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.182-184
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• 2015

We have developed a novel LED display architecture with RGGB 4sub-pixels rendering. LED light control filter algorithm is proposed in order to reduce color fringes by sub-pixel rendering which is a method of perceptual enhancement. The results show that it has 2 times higher perceptual resolution without artifacts.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.475-480
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• 2012

This study on the methode is easied to distinguish with emotional visual lighting on AtoN facility using 3colors LED, and which is controlled to on-off switching of approach light in shore or harbor. The identification have easied to provide a differentiation between the AtoN facility of red and white light and surrounding light in harbor both sides. And the integrated controller have designed to left-right and serial sequential lighting system for harbor guidance using the GPS synchronous or timer. There is expectation effect that is prevent a confusion about distinguish of facility by ship's operator and to beautify a night scene of harbor, which is expressed to emotional identification lighting and variable color lighting on AtoN body by vertical layer color lighting using LED. In addition, the performance of AtoN is implemented to display with guidance light the harbor safety message by morse code lighting. Effectiveness of system is enhanced that age and power consumption reduce by candle alternated high light LED.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.1-9
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• 2013

The experimental study of the white LED lighting focused on the readability in interior space according to age group is conducted realizing importance of the lighting environment and necessity of lighting study depending on the user situation. The results of study represent that a teenager does not show sensitive reaction to change of the color temperature and illuminance. The people in 20s and 30s prefer neutral white LED lighting and are very sensitive to change of the light environment. The people in 50s and 60s prefer high illumination and cool white LED lighting series. People of all ages highly appraise 6000K of 700 lux and 4000K in the illuminance range of 700 lux to 1000 lux for readability. The white LED lighting of color temperature 4000K is estimated as a suitable environment for readability in a wide range of illumination.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.6-17
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• 2015

In this paper, colors of broadcast lightings composed of Red, Green, and Blue LED(Light Emitted Diode) can be linearly and quantitatively controlled in low illuminance. Because LED cannot emit uniform illuminance in low illuminance, the colors of RGB LED are unmixable. Furthermore, the illuminances are nonlinear with the dimming values of the RGB LED due to the nonlinearity of the output illuminance with the current through the LED. This nonlinearity generated errors of the target colors and illuminances. The proposed algorithm set up the target colors, which is expressed by the color coordinates in CIE 1931 color space, and the target illuminances. Then the illuminances of RGB LED were calculated using color mixing theory. The calculated illuminances determined the dimming values of the RGB LED for transmission via DMX512 communication. After the broadcasting lighting received the dimming values of the RGB LED via DMX512 communication,.RGB LED can emit target color and illuminance, and be controlled by calculating the PWM(Pulse Width Modulation) duty ratio of the hybrid LED driver which be considered the nonlinearity for the illuminances of the LED. As a result, the proposed algorithm can linearly and quantitatively control the colors and illuminances in full range of illuminance. Then we verify experimentally that the errors of the emitted color coordination x, y and illuminance are 2.27%, 3.6% and 1.5%, respectively.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.145-147
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• 2003

This paper presents a method of improvement of color mixing in an RGB LED white lamp. The deviation from white light after RGB color mixing results mainly from the difference in the ray direction among LEDs. The authors propose a method using tilted lenses covered over each LED to deflect the overall direction of the ray generated from far-sited LEDs toward the center axis of the lamp. The degree of improvement is evaluated using a color discrimination method based on McAdam ellipse.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.120-126
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• 2014

Translucent green colored opal glass was fabricated to substitute polycarbonate diffuser of LED lighting in order to solve the durability problem. Batch materials of green colored opal glass with the composition of calcium phosphate for opacifier and iron oxide for colorant were made and melted at $1550^{\circ}C$. As the results, translucent green colored opal glass was obtaind, which had excellent optical properties compare with nomal color glass for the diffuser of LED lighting, with no dazzling from direct light by high haze value over 90 % and low parallel transmittance value about 1 %. Therefore, it is concluded that this translucent green colored opal glass can be used for the glass diffuser materials of LED lighting with high heat resistance and high durability to substitute polycarbonate diffuser.

• 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.

• Environmental Engineering Research
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• v.23 no.2
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• pp.205-209
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• 2018

The spectral composition of light can affect the growth and biochemical composition of photosynthetic microalgae. This study examined the use of light filtering through a solution of soluble colored additives, a cost-effective method to alter the light spectrum, on the growth and lipid production of an oleaginous microalga, Nannochloropsis gaditana (N. gaditana). Cells were photoautotrophically cultivated under a white light emitting diode (LED) alone (control) or under a white LED that passed through a solution of red and yellow color additive (4:1 ratio) that blocked light below 600 nm. The specific growth rate was significantly greater under filtered light than white light ($0.2672d^{-1}$ vs. $0.1930d^{-1}$). Growth under filtered light also increased the fatty acid methyl ester (FAME) yield by 22.4% and FAME productivity by 80.0%, relative to the white light control. In addition, the content of saturated fatty acids was greater under filtered light, so the biodiesel products had better stability. These results show that passing white light through an inexpensive color filter can simultaneously enhance cellular growth and lipid productivity of N. gaditana. This approach of optimizing the light spectrum may be applicable to other species of microalgae.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.27-34
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• 2015

There has been a critical issue in optical simulation of phosphors in LEDs due to their light-reabsorption properties. To improve the accuracy of optical modeling for a white LED package, we utilized the spectrum data of the phosphor-dispersed encapsulant film instead of the phosphor powder. By measuring white LED packages with green and red phosphors, the maximum difference between simulation and experimental results of a color temperature, a color rendition index number and a color coordinate corresponds to ${\Delta}T=95K$, ${\Delta}Ra=1.7$ and ${\Delta}xy=0.007$, respectively. Based on those results, the proposed method can well explain the change of emission spectra of white LEDs with more than two phosphors which introduce the complex optical phenomena such as absorption, reabsorption, light emission, reflection and scattering, etc.