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.

http://koreascience.or.kr:80/article/JAKO201532742223513.pdf

Design and Implementation of LED Lighting System with Adjustable Brightness and Color Capability

At the on-site of broadcasting production, the light source of tungsten halogen has been used as a primary light source for representing video images. Although tungsten halogen light has drawn attention in terms of the color reproducibility which is more similar to the sun light than that of other light sources, meanwhile it had problems in energy efficiency. Recently, the LED light source with high efficiency and long lifetime of the energy source has started getting attention as a substitute light source at the broadcast field. Because of the unique light emission principles, compared with tungsten halogen, LED light source has different characteristics in the quality of the light projected from the light source and color reproduction of the video image through a camera. These characteristics cause the delayed introduction of the LED as the broadcast light source. In this study we measured the quality characteristics of the flatness of the color reproduction and light of the LED light source and will present the experimental data whether it is suitable as the broadcasting light source compared to a reference light source of tungsten halogen. In addition, we suggested the future challenges and standards which are needed to expand usage of LED as a broadcast light source.

A Study on Color Reproduction and Flatness of the LED Light Source in Broadcasting Lighting

This study is intended to compare physical properties of fluorescent luminaires with ones of LED luminaires so as to analyze fundamental characteristics of LED luminaires. For this, a comparative analysis of uniformity ratio of illuminance and luminance distribution of these two luminaires was made, and materials for applying LED luminaires to interior construction space were prepared. This study was carried out in four stages. First, a theoretical review on LED illumination light source was made compared with the existing luminaires. Second, a mock-up to control experimental variables to meet the objective of this study was manufactured. Third uniformity ratio of illuminance and luminance distribution of each luminaire were measured by using the mock-up. Fourth, a comparative analysis of uniformity ratio of illuminance and characteristics of luminance distribution of the existing fluorescent luminaires and LED ones was made. As a result of the study, the uniformity ratio of illuminance of LED luminaires, 0.559, was higher than one of the existing fluorescent luminaires, 0.522. Namely, it was shown that illuminance distribution of LED luminaires was uniform and global diffuse was good. As a result of measuring luminance distribution, it was found that luminance distribution of LED luminaires was more uniform than one of the existing fluorescent luminaires. The maximum luminance of fluorescent luminaires and LED luminaires over the wall was and respectively. Namely, the maximum luminance of fluorescent luminaires was higher than one of LED luminaires. The average luminance of fluorescent luminaires and LED luminaires was and . Like this, the average luminance of LED luminaires was higher than one of fluorescent luminaires. Considering these results, it`s thought that LED luminaires can give a person in the room a more comfortable working environment than fluorescent luminaires.

Study on Analysis of Characteristics of Illuminance and Luminance Distribution of LED Luminaires

The ultimate purpose of the study is to develop a discomfort glare forecasting formula that can be practically used in Korea in order to effectively forecast discomfort glare considering the optical characteristics of the Koreans. The study was to examine the relations between discomfort glare and the variables such as luminance, background luminance, solid angle, luminous area and louver. To this end, experiments were conducted in a mock-up office that emulates the lighting environment of an ordinary office. The study was conducted by four steps as follow. First, previous studies on discomfort glare rating to define and rate discomfort glare were analyzed and modified to be applied to the experiments of this study. Second, experiment variables, variable scope, evaluation objects and evaluation points were determined after review on existing discomfort glare evaluation experimental formulas. Third, experiments were conducted in a mock-up office to be able to control variables. Finally, sensitivity of experiment variables were analyzed through examination of the relation between discomfort glare and the variables such as luminance, solid angle, louver, luminous area and subject`s position. The result showed that the most influential variables on discomfort glare of an artificial light source is luminance and louver, luminous area and subject`s position(solid angle) followed.

Study on Sensitivity of Variables of the Experiment to Evaluate Discomfort Glare of Interior Artificial Illumination

Evaluating comfort of illumination environment of building interior is recognizing the degree of glare causing discomfort. Currently, to use the experimental formula for discomfort glare studied abroad it would be not appropriate because each races feel about the degree of glare differently. Therefore, this study aim to make up prediction formula for evaluating discomfort glare reasonably from Koreans` vision and it proceeded with 4 stages as follows: First, after reviewing the existing discomfort glare evaluation formula, I selected experimental variables. Second, I made a mock-up that I can control experimental variables and conditions according to the purpose of this study. Third, 1 conducted discomfort glare evaluation experiment. Finally, compared with UGR evaluation method suggested for Westerner in prior studies. In conclusion, 1) it`s proved that discomfort glare is influenced highly by a light source luminance, background luminance and location of testee and the line of vision. 2) In interior discomfort glare experiment whether the glare light source is placed within range of vision or not has more significant influence than the distance between the light source and testee. 3) I compared and analyzed with UGR, the most representative discomfort glare evaluation system and I found there is a little difference in the results. This shows discomfort glare of Koreans and Westerners are different.

Won-Do Kim

Papers

Study on Analysis of Characteristics of Illuminance and Luminance Distribution of LED Luminaires

Study on Sensitivity of Variables of the Experiment to Evaluate Discomfort Glare of Interior Artificial Illumination

The Fundamental Research for Discomfort Glare Evaluation of Building Interior Artificial Illumination