• 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 IKEEE
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• v.15 no.4
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• pp.261-266
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• 2011

In this paper, new efficient lighting control system for light devices is proposed to reduce power consumption and increases LED life-cycle and heat efficiency of LED lighting module. The new proposed lighting control system for light devices divides into 4 stages according to the illuminance surrounding by measuring illuminance and apply to automatic pattern lighting algorithm. And via level check will be light up for set time by applying intersection lighting algorithm of magic square pattern forming a fully symmetrical. Experimental analysis results, shows heating value and power consumption reduced to maximum 30 percent and lifetime of LED improved to maximum 60 percent in comparison with previous lighting system so applying system to LED streetlight, stable and high energy efficiency can be acquired.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.1-13
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• 2011

The purpose of this study is the realization of LED light environment closely resembling the Autumn daylight which people feel comfortable with. This research was conducted through an optical experiment and Emotional evaluation through human's eyes. Human beings are affected by the color of light, quality and light intensity. Unlike the past when human beings have worked mainly in daylight, the urbanites today spend most of the time in indoor spaces. Therefore, the artificial light is needed to strive toward a spectrum of daylight. This study is purposed to provide the pleasant light environment for human beings and build its database. This study course is expected to contribute to the new design methodology of the related fields under the development of the LED emotional lighting color.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.8-17
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• 2012

Unlike traditional lightings, LED lighting is one of objects that sends user an emotional segments through brightness control from various color temperature and dimming control. Also, within present interior lighting environment, emotional researches about traditional fluorescent lamp and newly implemented LED lighting environment are in active progress. Despite the fact adjectives describing emotions and scale modeling have been repeatedly used in many cases for a long time, there seems to be a lack of results in reliability, and there is a limitation for applying into actual lighting design. The purpose of this study is to construct an actual sized test-bed, which is used to draw out one's emotional words of behavior patterns from inner emotional experiences about lighting environment in an office space. Also, having fluorescent lamp and LED lighting as the main test subjects, we have tested emotional parts according to the changes of color temperature and adjective vocabularies chosen from user's action, and we have compared and analyzed the drawn out data. Also, having fluorescent lamp and LED lighting as the main test subjects, we have tested emotional parts according to the changes of color temperature and adjective vocabularies chosen from user's action, and we have compared and analyzed the drawn out data.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.2
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• pp.103-111
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• 2012

This paper introduces a novel concept of 'A Green LED Sensitivity Lighting System' which can automatically estimate QoS(quality of service) and emotional requirements of user using smart phone. And it can intelligently control ambient illumination lamp to conserve electric energy and to satisfy human sensitivity. The proposed system has 4 control modes; emotional lighting, smart lighting, green lighting and realistic lighting modes in order to comfort man's emotion, to maximize work efficiency, to save energy consumption and to make the entertainment more fun, respectively. When we choose green lighting mode for indoor office situations, an elaborate simulation shows that the proposed system with home network can reduce the energy by 50% compared to conventional light control system with a fixed time-based switching.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1625-1633
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• 2012

In the lighting industry, a Lighting Emitting Diode (LED) is increasingly used because of many advantages and a eco-friendly product comparing with the conventional lighting. However, the LED lighting has to include various AC/DC converters because the direct current is used for the LED lighting. Among a lot of power converters, the flyback converter is widely used for the LED lighting and includes some electrolytic capacitors for the voltage regulation. But the electrolytic capacitor has shorter lifetime than the LED element. It makes the expected life-time of the converter having the electrolytic capacitor shorter than the LED element. This paper proposes the single-stage PFC flyback converter without electrolytic capacitors. To verify the performance of the proposed converter, simulated and experimental works were carried out.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.5
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• pp.579-586
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• 2015

In this paper, we design and implement a lighting system which has a capability of adjusting brightness and colors of LED module. The lighting systems is consisted of RGB and white LEDs controlled by a micro-processor. All colors in nature can be synthesized in our lighting system by controlling brightness of 4 color LEDs individually. The current flowing to LED is limited to a maximum set value to extend the LED life time using PWM current control. The control module also includes the function that it can save and load brightness and color data set by the user. The implemented lighting system passed the electromagnetic compatibility(EMC) test such that it can be used as a commercial product.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.54-59
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• 2011

LED lightings typically do not fail catastrophically during use. However, over time the light output will gradually depreciate. Even if there are same LED lighting, they are so different at all. because of dissimilar the use and environment of each LED lighting. In this paper, we make a description of reliability analysis procedures for the degradation data using collected field data. Reliability analysis procedures are consisted of estimating degradation models and failure time, verification of distribution and parameters of the distribution, and reliability measures estimation. At some point in time, the light emitted from an LED lightings depreciates to a level where it is no longer considered adequate for a specific application.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1020-1026
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• 2012

In this paper, we proposed a RTOS-based lighting control system to improve energy efficiency. This proposed system, real time process was designed to the specified division of the LED streetlight control module for the RTOS-based lighting control into three different tasks. The first task transmits LED lighting signal by measuring illuminance, and the second task transmits motion detecting signal using motion detector. In the third task, lighting control to LED was designed through passed control signal from other tasks The execution status was examined ports that are directly to the ATmega128 MCU for the verification of the system, and illuminance distribution and operating conditions were verified through LED street field test. The proposed RTOS-based lighting control system has brought improving system performance and also facilitate an addition of other functions, and it was possible to optimize energy saving by intelligent lighting pattern control.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.7-14
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• 2011

Many countries and researchers in the lighting field have focused on the LED light source as a solution to energy savings and environmental pollution. The LED light source consumes less power, has a long life and is highly economical. It is vibration and shock-resistant, and environment friendly as well. But LED lighting has some problems. In particular, the photobiological safety of LED light sources is emerging as an issue. Ultraviolet radiation from the LED light source emitted directly to the human body over a long period of time is harmful. In this paper, UV radiation from white LED was measured. Finally, the LED light source emits UV radiation, but it is relatively small when compared to others.