• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.284-288
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• 2015

The color temperature flexibility-typed Lighting Emitting Diode(LED) lighting control system proposed in this thesis employs Pulse Width Modulation(PWM) technique to control the brightness of LED lighting. The LED lighting used as a light source has 20W downlight composed of two types of LED chips: one is Warm White and the other is Cool white. One multi-sensor module consisting an infrared sensor, an illumination sensor, and a temperature sensor was made, to which Bluetooth wireless communication technique was applied to enable a smartphone application to control lighting brightness and identify the information collected from the sensor. CS-1000, a spectroradiometer, was used to measure LED dimming control and the changing values of a color temperature in eight steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5600K of Cool White LED.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.359-364
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• 2011

The study uses department of the sensitivity and fuzzy reasoning, one of artificial intelligence algorithms, so that develop LED lighting system based on fuzzy reasoning for systematical control of the LED color temperature. In the area of sensitivity engineering, by considering the relation between color and emotion expressed as an adjective word, the corresponding sensitivity word can be determined, By taking into consideration the relation between the brain wave measured from the human brain and the color temperature, the preferred lesson subject can be determined. From the decision of the sensitivity word and the lesson subject, we adjust the color temperature of RGB (Red, Green, Blue) LED. In addition, by using the information of the latitude and the longitude from GPS(Global Positioning System), we can calculate the on-line moving altitude of sun. By using the sensor information of both temperature and humidity, we can calculate the discomfort index. By considering the altitude of sun as well as the value of the discomfort index, the illumination of W(white) LED and the color temperature of RGB LED can be determined. The (LED) sensitivity lighting control system is bulit up by considering the sensitivity word, the lesson subject, the altitude of sun, and the discomfort index The developed sensitivity lighting control system leads to more suitable atmosphere and also the enhancement of the efficiency of lesson subjects as well as business affairs.

• 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.

• 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.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.247-253
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• 2011

In this paper, we propose and implement the automated brightness control system using distance measuring sensor for reducing the power consumption of emotional lighting device. In order to reduce the power consumption of emotional lighting devices which express continuous color changes, the proposed device measures the distance continuously using ultrasonic sensor and by using this, it also performs PWM Dimming control. The lighting device is composed of micro controller, LED driver, ultrasonic sensor, communication module and so on. And the device performs the real time brightness control by adapting the measured distance information from ultrasonic sensor to PWM signals. From this experiment, we implement the active lighting system which minimizes unnecessary power consumption during user's absence by adapting existing energy reducing techniques.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.10-16
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• 2013

This study performed a subjective evaluation of the Semantic Differential (SD) method for living room activities to evaluate the living room lighting environment and investigated the relationship between these through luminance distribution in the space. As a result, three factors-"lightness", "emotion" and "calmness"-have been grouped together. According to the analysis of experimental variables, difference has been observed depending on color temperature, the dimming of the ceiling & cove lights and the use of down lights and a bracket. 'Conversation with Family', 'Having Fun with Family', 'Entertaining Guests' and 'Reading a Book or Newspaper' requires "lightness". In terms of "emotion"-centered activities, 'Watching TV' is the highest, but all three factors are related. In terms of "calmness"-centered activities, 'Relaxing' is the highest.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.9
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• pp.8-17
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• 2012

This paper proposes high performance control of light emitting diode(LED) drive system for liquid crystal display(LCD) backlight. The CCFL(cold cathode fluorescent lamp)was used to a conventional LCD backlight. Due to improvement on luminous efficiency, long life and wide color gamut, LED has gradually substituted for CCFL as backlight. The backlight using LED is necessary to use many LED. For that reason, the LED backlight is using a lot of LED driving circuits. The many LED driving circuit is generated a current deviation between LED. Eventually, it is caused brightness deviation between LED. Therefore, this paper improves the current deviation using transformer and balancing capacitor to solve this problem. Also, for accurate and uniform brightness control, this paper is applied the artificial intelligent control to a dimming control. This paper is compared with conventional system, and validity of this paper proves through that result.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.33-38
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• 2011

In this paper, the effect of pulse current and generated heat on characteristics of the LED is measured and evaluated. For experiments, the LED driving circuit and digital logic which determines period and duty ratio of lighting are designed. At rated current, the temperature and optical characteristics of the LED with change in duty ratio and period are compared, and those of the LED with change in duty ratio and existence of cooling fan are also compared at constant average current. As a result, frequency does not affect device temperature and optical characteristic of the LED but duty ratio does. Also, the cooling fan is less effective on those of the LED at rated current.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.76.3-76.3
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• 2019

Intracluster stars are believed to be gravitationally bound to a galaxy cluster, however, not to individual cluster galaxies. Their presence is observed as diffuse light typically in the central region extended from the brightest cluster galaxy. The diffuse light, often referred to as intracluster light (ICL), is difficult to quantify in distant high-redshift galaxy clusters because of the significant surface brightness dimming although ICL observations in high-redshift clusters provide powerful constraints on the origin of intracluster stars. In this poster, we present ICL study of the distant galaxy cluster SPT2106-5844 at z=1.132 with Hubble Space Telescope IR imaging data. With careful control of systematics, we successfully quantify the total amount of the ICL, measure the color profile, and obtain its two-dimensional distribution. Our measurement of the high abundance of the intracluster stars in this young cluster favors the ICL formation scenario, wherein production of intracluster stars are predominantly associated with the BCG formation.