• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1219-1225
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• 2003

According to the increase of lifetime and efficiency, the interest in the pLED has dramatically increased recently because pLED can be applied to large-size and flexible displays. The core process in the manufacture of pLED is the printing process of red, green and blue light emitting polymers (LEP), and inkjet printing method is one of the promising technology to print red, green and blue LEP on glass substrates. In this work, we developed a multi-head inkjet patterning system with 3 heads for each color. The developed inkjet patterning system is composed of the precise positioning system, head controller circuit, real-time ink drop evaluation system, maintenance system, and stable ink supply system. Finally, we investigated the stability and reliability of the system by printing red, green and blue LEP on the dummy substrate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1312-1316
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• 2014

The color and the installation position of the LED lamp for night voyage of the ship are changed by the purpose of it. The power dissipation occurs because a navigation light is on and off or continuously on. In addition, in case that the light is produced by operating generator in the ship, it's very inefficient except that it's on a voyage. Therefore in this dissertation, we construct auxiliary power system for the LED lamp of the ship, producing and developing a module, a panel, and a charging system using Dye-sensitize Solar Cell.

• Journal of Information Display
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• v.13 no.1
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• pp.37-42
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• 2012

An empirical functional form was suggested for the analysis of the emission spectrum of high-power light-emitting diode (LED) consisting of a sharp blue peak from the LED chips and a broad yellow peak from the phosphor layer. The peak positions, half widths, shape parameters, and amplitudes of these two peaks were reliably obtained as a function of the temperature, and the results were discussed qualitatively in relation with the junction temperature. The adoption of an inert liquid was found to have significantly reduced the LED temperature and the color shift of the emitted light. The phenomenological approach used in this study may be helpful in the simulation of the LED spectrum under various thermal conditions, and may thus be helpful in the improvement of the device performance.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.572-580
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• 2020

Recently released AI speakers show a pattern of interacting with the user by mainly with voice and simultaneously displaying simple and formal visual feedback through status LED light. This is due to the limitations of the product characteristics of the speaker, which makes it difficult to interact variously, and even such visual feedback is not standardized for each product, and thus does not give a consistent user experience. By maximizing the visual elements that can be expressed through color and abstract movement to assist voice feedback, the product can provide the user with an extended experience that includes not only functional satisfaction but also emotional satisfaction. In this study, after analyzing the interaction methods of the existing AI speakers, we examined the theory of color communication in order to expand the visual feedback effect, and examined the meaning and expression technique of Color Field Painting, an art genre that maximizes the emotional experience by using only color. Through this, the AI speaker's visual communication function was expanded by designing a way to feedback communication status using LED light.

• 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.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.602-606
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• 2008

LCD is supplied light by BLU(Back Light Unit) and the light represents color by each color filter. Also LCD adjusts the amount of light by controlling liquid crystal between the glass of upper plate and one of lower. However, it is impossible to completely exclude light due to the structural and physical characteristic of liquid crystal. Therefore, on transfering light through optical sheet and liquid crystal, many problems are generated. They are related with energy efficiency and get effective for the contrast of LCD to have lower contrast ratio than other display devices. To solve the problems, many techniques have been studied and developed but don't exist keys to solution for them. Among methods, local dimming is one example to be applied to LCD. In this paper we propose image processing algorithm for local dimming of BLU of LED used as light source. The proposed algorithm extracts maximum luminance signal and lights using each extracted signal on segmented region of BLU. Also the proposed algorithm generates image signal in corresponding to luminance of the segmented region and supplies them with LCD panel to represent image with improving luminance ratio.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.727-731
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• 2005

Design and manufacturing process of a full color LED microdislay fabricated by standard CMOS technology and containing an array of aluminum / nanostructured porous silicon reverse biased light emitting Schottky diodes will be discussed. Being of a solid state construction, this microdisplays are cost-effective, thin and light in weight due to very simple device architecture. Its benefits include also super high resolution, wide viewing angles, fast response time and wide operating temperature range. The advantages of full integration of an LED-array and driving circuitry onto a Si-chip will be also discussed.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.6
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• pp.830-837
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• 2016

The purpose of this study was to investigate the effect of monochromic light-emitting diode (LED) light with different color on the growth and reproductive performances of white Roman breeder geese. A randomized complete batch design was utilized for the trial, and the replicate was regarded as one batch. Twenty ganders and fifty-five dames were used in batch 1 (started on 2011/6/17 and ended on 2012/1/31), thirty ganders and eighty-four dames were used in batch 2 (started on 2012/3/23 and ended on 2012/10/26), and thirty ganders and seventy-two dames were used in batch 3 (started on 2013/3/12 and ended on 2013/12/20). Two hundred and ninety-one geese were randomly assigned to 6 rooms in an environmentally controlled house. They were randomly allotted into one of three monochromatic light treatments: Blue, red, or white. The results showed that there was no significant difference in body weight among the three lighting groups at any point throughout the experimental period. However, compared to the blue light group, significantly more eggs were produced by the red and white light groups (p<0.05). Furthermore, the laying period of the red light group was significantly longer than that of other two groups (p<0.05). In conclusion, our results suggested that red LED-light has the best effect on reproductive performance (i.e. longer laying period and higher total eggs number) at 30 lux light intensity, and is therefore a better choice for the management of breeding geese than blue or white LED-light.

• Journal of Bio-Environment Control
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• v.19 no.3
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• pp.140-146
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• 2010

This experiment was conducted to find the day and night temperature combination and the light-emitting diodes (LEDs) on the most effective globe coloration and growth of Chamecereus silvestrii f. variegata 'Hee-Mang'. The $L^*$value, $a^*$value and $b^*$value were all significant difference in the yellow globe color expression in the day and night temperature combination. Especially, the bright yellow color and visual value were the highest in the temperature combination, the day temperature of $20^{\circ}C$ and night temperature of $20^{\circ}C$. Globe color quality was lowered from the day temperature of $25^{\circ}C$ and night temperatures of $5^{\circ}C$ and $10^{\circ}C$ combination. In light-emitting diodes (LEDs) treatments, $a^*$value and $b^*$value are significant difference. A unique beautiful yellow coloration and globe quality were maintained the $a^*$value of +5.23, $b^*$value of +39.9 in a red LED. The optimum temperature range and light-emitting diodes (LEDs) on the globe color expression were the most effective the day temperature of 200e and night temperature of $20^{\circ}C$ and a red LED. In addition, the outer globe color quality of Chamecereus silvestrii f. variegata cultivation, rather than the light environment improvement is better in a proper temperature environment to keep. Especially, a unique globe color expression of yellow lines was most effective in a red LED.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.639-649
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• 2021

Background and objective: Various images from visual display terminals (VDTs) as well as living lighting are important parts of our daily life; thus, properly controlling the lighting environment - that is, illuminance, color temperature and good images from VDTs - can have a substantial effect on improving the mental health and work efficiency in everyday life. We examined electroencephalography (EEG) and heart rate variability (HRV) responses to various lighting conditions in 25 university students as they viewed images of a green landscape or traffic congestion. Methods: EEG was performed in darkness and when the room was illuminated with 10 different light-emitting diode (LED) color temperatures, while the EEG and HRV responses to green landscape or traffic congestion image stimuli were measured in darkness and during room illumination with three different LED color temperatures. Results: We found a significant difference between darkness and high LED illumination (400 lx) at 7 (CZ, F4, FZ, O1, O2, OZ, and T6) of 30 channels, while the alpha wave activity increased during darkness. In the second experiment, the green landscape image stimuli in the 30 lx-2600 K lighting condition elicited theta wave activity on the EEG, whereas the traffic congestion image stimuli under high LED illumination elicited high beta and gamma wave activities. Moreover, the subjects exhibited better stress coping ability and heart rate stability in response to green landscape image stimuli under illuminated conditions, according to their HRV. Conclusion: These results suggest that lower color temperatures and illumination levels alleviate tension, and that viewing green landscape image stimuli at low illumination, or in darkness, is effective for reducing stress. Conversely, high illumination levels and color temperatures are likely to increase tension and stress in response to traffic congestion image stimuli.