• Transactions on Electrical and Electronic Materials
• /
• v.18 no.1
• /
• pp.35-41
• /
• 2017

This study looks at optimizinge light redistribution to improve the overall illuminance uniformity of commercial IRED modules. To obtain uniform illumination over a prescribed rectangular area, a freeform surface lens was evaluated using TracePro. The LED light overall illuminance uniformity regulated in KSC 7658 was verified using Relux software. Experimental test results showed 0.81 overall illuminance uniformity for rectangular light distribution of LED lights having a radiation angle of $80^{\circ}$. After fabricating prototype IRED lights based on these simulation results, illuminance performance was observed when used as actual IRED lighting with a nighttime CCTV system. Image observation photographs of the prototype $80^{\circ}$ rectangular IRED lights confirmed that object images can be seen clearly owing to high overall illuminance uniformity, and that dark regions of the CCTV screen were not shown.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.4
• /
• pp.954-964
• /
• 2015

In this research, an overlapped illumination model was newly proposed for designing a freeform LED lens with a uniform illuminance distribution on its illuminating plane. Based on the proposed model and conventional illumination models, freeform lenses were designed and their performances and tolerances were compared. As a result of the tolerance analysis about thickness change in lens, position, size change, central direction change of light emission and characteristic change in LED source. This proposed model and divergent illumination model are similar to the performance about central direction change of light emission in LED source. but the uniformity illumination value in this proposed model is more remarkably value than it in divergent illumination model about characteristic change in LED source.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.1
• /
• pp.157-164
• /
• 2017

In this research, the overlapped illumination model was used for designing a freeform LED lens with a uniform illuminance distribution on its illuminating plane, and their performances and tolerances were compared. And, the illuminations on a illumination plane was measures for change with average illuminance and illuminance uniformity. As a result of the tolerance analysis about z-axis direction change, thickness change in lens and tilt change of light emission and characteristic change in LED source, overlapped model and divergent illumination model are similar to the performance about Z-axis direction change of light emission in LED source. but the uniformity illumination value in this overlapped model is more remarkably value than it in divergent illumination model about thickness change in LED lens. Also, even though the lens based on a divergent illumination model showed good performance compare to the lens based on an overlapped illumination model, the latter was less the deviation to variation of LED beam radiation ability.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.1
• /
• pp.16-18
• /
• 2012

LED lighting systems that combine lighting capability, emotional and physiological characteristics are required for lighting source and multifunctional applications. In this work, Simulation studies using optical analysis software packages, Light Tools, are presented. This is done to estimate the uniformity ratio of illuminance and photosynthetic photon flux density (PPFD) of the periodic 2D lattice arrangements, such as square, diamond, two-way bias quadrangular, hexagonal, and Kagome lattices, under the same transmissivity, absorptance and reflectivity. It has been found out that the two-dimensional Kagome lattice arrangement exhibited high uniformity ratio of illuminance and PPFD compared to other lattices. Accordingly, these results can be used to guide a design and improve the lighting environment which in turn would maximize the uniform distributions of illuminance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.11
• /
• pp.6-17
• /
• 2015

In this paper, colors of broadcast lightings composed of Red, Green, and Blue LED(Light Emitted Diode) can be linearly and quantitatively controlled in low illuminance. Because LED cannot emit uniform illuminance in low illuminance, the colors of RGB LED are unmixable. Furthermore, the illuminances are nonlinear with the dimming values of the RGB LED due to the nonlinearity of the output illuminance with the current through the LED. This nonlinearity generated errors of the target colors and illuminances. The proposed algorithm set up the target colors, which is expressed by the color coordinates in CIE 1931 color space, and the target illuminances. Then the illuminances of RGB LED were calculated using color mixing theory. The calculated illuminances determined the dimming values of the RGB LED for transmission via DMX512 communication. After the broadcasting lighting received the dimming values of the RGB LED via DMX512 communication,.RGB LED can emit target color and illuminance, and be controlled by calculating the PWM(Pulse Width Modulation) duty ratio of the hybrid LED driver which be considered the nonlinearity for the illuminances of the LED. As a result, the proposed algorithm can linearly and quantitatively control the colors and illuminances in full range of illuminance. Then we verify experimentally that the errors of the emitted color coordination x, y and illuminance are 2.27%, 3.6% and 1.5%, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.4
• /
• pp.13-19
• /
• 2003

Giving teachers and students the clean visual environment, the classroom lighting is an important part that prevents the decrease of the visual acuity and improves the studying environment. In order to improve the classroom lighting, a proper blackboard luminaire is to be developed. This paper explains how to design the optical form of the high efficient reflector which offers the uniform illuminance at the vertical surface of the blackboard and, after all, the problem of a large source in reflector design process is explained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.9
• /
• pp.1-7
• /
• 2008

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 $180.6[cd/m^2]$ and $155.26[cd/m^2]$ 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 $44.32[cd/m^2]$ and $58.65[cd/m^2]$. 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.

• Journal of Korean Ophthalmic Optics Society
• /
• v.4 no.2
• /
• pp.33-38
• /
• 1999

To investigate the image-forming property of optical system having Gaussian amplitude for polychromatic source, we calculated the chromaticity variation and the illuminance distribution. Considered polychromatic sources in this paper are A light which is on incandescent-tungsten lamp, C light which is a daylight, and $D_{65}$ light which is a extend daylight to the near ultraviolet. The polychromatic sources represent the different chromaticity values at a geometrical image point. The chromaticity variation of optical system having a Gaussian amplitude is smaller than that having an uniform amplitude. The illuminance distributions for polychromatic sources present nearly the same values, and the depth of focus for optical system having a Gaussian amplitude is wider than that having an uniform amplitude. From these results, we know that the depth of focus increases and the chromaticity variation decreases, when the incident light amplitude is modulated from an uniform amplitude to a Gaussian amplitude.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.97-100
• /
• 2008

The daylight responsive dimming system is an energy saving system that automatically controls lighting output of artificial lighting according to available daylight in inside, as well as keeps uniform workplace illuminance. The basic three components of the daylight responsive dimming system consist of a photosensor, a controller and a dimming ballast. This paper is a fundamental study of photosensor modeling for the daylight responsive dimming system. The correlation between photosensor illuminance on the ceiling and workplace illuminance is an important factor to accuracy of system performance, so that the purpose of this study is to improve accuracy for daylight responsive dimming system. This study performs to derive the optimized conditions of photosensor using the RADIANCE.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.3_1spc
• /
• pp.615-621
• /
• 2013

A blind system for window glass has been designed and manufactured as a CapStone Design project at Seoul National University of Science and Technology. This system automatically controls the interior illuminance to maintain a uniform temperature. The aim of this project was to support an air conditioning system and heating equipment to maintain a good indoor environment. Proportional integral differential (PID) control using cadmium sulfide (CdS) sensors was applied to control it. Polaroid film was attached to the new blind system to reflect sunlight. It was found that the system had the potential to reduce energy consumption and may be used with a building energy management system (BEMS).