• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.518-524
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• 2020

This study conducted basic research on an LED lighting design to improve the learning effect from brain wave analysis. The ideal environments of mathematics, language, and creative region can be different. Inside the space where the lighting environment can be experienced directly, the test subject consisted of common elements. Other lighting was blocked completely in controlled lighting conditions. The brain waves were analyzed according to the change in color temperature and illumination. The analyzer used was fabricated by EMOTIV Company. In the variable RGB LED light, the color of the light was measured, and the brain wave of each subject was determined. LED lights have variable color temperature (3000 [K], 4500 [K]. 250 [lux], 70% -350 [lux], 100% -500 [lux]). As research results, the highest concentration in a mathematics study was in the general condition of a high color temperature, in which the optimal condition was a 6000[K] color temperature and 350[lux] illumination. The optimal condition for a language study was a 4500[K] color temperature and 500[lux] illumination, and that of the creative study was 3000[K] color temperature and 500[lux] illumination. Overall, the possibility of emotional ability and concentrated learning efficiency can be improved by the LED lighting design with the color temperature and illumination.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.119-124
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• 2007

24" LCD Monitor용 LED BLU를 개발하기 위하여 1.5W R,G,G,B가 하나의 PKG에 들어있는 LED를 이용하여 Direct type의 Back Light Unit을 개발하였다. 방열 및 휘도 균일도를 고려하여 LED part를 설계, 개발 하였고 LED를 pulse로 구동하기 위하여 Switching circuit이 포함되는 구동회로 부분을 설계, 개발하였다. 또한 Color Sensor와 ICM (Integrated Color Management) IC를 사용하여 Color를 Control하는 제어회로 부분도 개발을 하였다. 제어회로 부분을 개발하기 위하여 MicroController를 사용하였으며 ICM IC와의 통신을 위한 부분도 개발하였다. 이러한 구성을 개발하여 시제품을 직접 제작하였다. 평가를 위하여 성능시험을 실시하였고 광학적인 평가도 시행하였다. 제작된 시제품은 $L558{\times}W359{\times}H30$으로 하였다. 휘도는 목표휘도를 이루었으며 균일도는 85% 이상이 되었다.

• Current Optics and Photonics
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• v.4 no.3
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• pp.247-252
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• 2020

Important determinants for selecting outdoor lighting are the color-rendering index (CRI) and scotopic-to-photopic (S/P) ratio of the lighting units. The higher the S/P ratio, the better energy savings and visual performance. In this study, CCT-tunable LED lighting units were optimized and fabricated by spectral combination of red, green, blue, and yellow LEDs. The measured results for RGB LEDs provided S/P ratios of 1.55~2.58 and those of RGBY LEDs gave 1.46~2.46 to the correlated color temperatures (CCTs) ranging from 2700 K to 6500 K, with CRI values of over 80 at the same time.

• 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.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.42-49
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• 2009

This paper proposes a driving current control method for a back light unit (BLU), consisting of red, green, and blue (RGB) light-emitting diodes (LEDs), whereby an RGB optical sensor is used to check the output color stimulus variation to enable a time-stable color stimulus for light emission by the RGB LED BLU. First, to obtain the present color stimulus information of the RGB LED BLU, an RGB to XYZ transform matrix is derived to enable CIEXYZ values to be calculated for the RGB LED BLU from the output values of an RGB optical sensor. The elements of the RGB to XYZ transform matrix are polynomial coefficients resulting from a polynomial regression. Next, to obtain the proper duty control values for the current supplied to the RGB LEDs, an XYZ to Duty transform matrix is derived to calculate the duty control values for the RGB LEDs from the target CIEXYZ values. The data used to derive the XYZ to Duty transform matrix are the CIEXYZ values for the RGB LED BLU estimated from the output values of the RGB optical sensor and corresponding duty control values applied to the RGB LEDs for the present, first preceding, and second preceding sequential check points. With every fixed-interval check of the color stimulus of the RGB LED BLU, the XYZ to Duty transform matrix changes adaptively according to the present lighting condition of the RGB LED BLU, thereby allowing the RGB LED BLU to emit the target color stimulus in a time-stable format regardless of changes in the lighting condition of the RGB LEDs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.462-468
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• 2010

In this paper, the new efficient drive control technology based on the conventional full-color electric display board image processing method is proposed. This technology can be applied to high-fidelity large size panel TV and LCD Display, and makes high-fidelity-display-drive control possible in those. The proposed drive control technology can strengthen the image processing function of the conventional technology. Also, the automatic or manual adjustment of contrast, bright, tint, color, gamma revision, etc. can help to achieve high-fidelity vision. This technology can be adopted with lower price.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1515-1518
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• 2007

We demonstrate a high color gamut liquid crystal display (LCD) system (>100 %) by using a precompensated tri-chromatic LED-backlight module over a temperature range of (25 to $70^{\circ}C$), whose pre-compensated optical characteristic balances the spectral redshift and intensity decrease due to the temperature rising during operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.72-77
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• 2017

Lighting systems in modern society has been developed using a combination of IT technology and LED lighting for the purpose of bringing about changes in human-centered natural lighting and to take advantage of the efficient management and energy saving of LED lighting. In this paper, we propose an LED lighting control system that can control the color temperature and brightness of LED lighting composed of 3000K Warm LEDs and 6000K Cool LEDs by using an Arduino Due and wireless communication technology such as Bluetooth and Zigbee. The Arduino Due allows the color temperature of the lighting to be adjusted in several steps by controlling the duty rate and enables many lights to be controlled using Zigbee communication capable of 1: N multiple communication. By using Bluetooth communication, it is possible to easily control the LED lighting by means of a smartphone application, thereby enhancing the convenience for the user. The wireless communication based LED lighting control system implemented in this study cannot only provide human-centered lighting through its color temperature control from 3067K to 5960K and illumination control, but can also reduce the power consumption and be used as a natural-friendly lighting system.

• Journal of Convergence for Information Technology
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• v.11 no.12
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• pp.90-96
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• 2021

In this paper, we designed manufactured and design an integrated interface control unit that has compatibility with brightness control unit, color control unit, and existing control unit. As the implementation method the standard of DVI/HDMI transmission method is applied to the data transmission method, and the Sil 1169 IC is used as the applied IC. Brightness control is programmed to have eight levels of brightness control using the AT89C2051. Also, EPM240T100C5 IC was used for image and dimming data processing. As a result, it is compatible with the control unit using the DVI/HDMI transmission method manufactured by each company and can reproduce clear high quality full HD video according to the surrounding brightness through the full color LED display system.

• Journal of information and communication convergence engineering
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• v.19 no.4
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• pp.214-220
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• 2021

In this study, we constructed several scenarios that are required for LED lighting, and we designed and implemented an LED lighting control system to operate these scenarios to confirm their behavior. An LED lighting control system is a hybrid control board that is designed by combining LED controllers and SMPS, consisting of an AC/DC power supply part that converts AC 220 V into DC 12 V, and a drive and control part that controls the scenario and color of the LED module. Conventional LED light controllers have an input power of DC 12 V, so when using the input AC 220 V, the SMPS must be connected to the LED light controller. To eliminate this inconvenience, a hybrid LED lighting control system was configured to combine LED lighting controllers and SMPS into one control system. Furthermore, we designed a control system to represent the most appropriate color according to the input of the distance and illumination using a fuzzy control system to conduct computer simulations.