• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.29-38
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• 2013

In this paper, the illumination performances of three freeform lenses optimally designed for a point source were investigated for several LEDs with different source sizes, and also the tolerance characteristics of the lenses were analyzed. For comparison, two lenses with different sizes were designed with a divergent illumination model, and the last one was done with an overlapped illumination model. As the LED source size increased, the illuminance uniformity decreased more strongly, and the influence of a source misalignment on illumination performance became insignificant. However, the variation of LED radiation characteristics had strong effect on the illumination performance, irrespective of LED source size. Even though the lens based on a divergent illumination model showed superior performance compared to the lens based on an overlapped illumination model, the latter was less sensitive to the variation of LED radiation characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.30-41
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• 2011

This study performs the subjective evaluations of LED illumination conditions according to three types of color temperatures (7,000[K], 5,000[K], 3,000[K]) after employing LED illumination system in the classroom, Since the objective of this study is to develop an artificial lighting conditions like day light comfortable to students in the classroom, the learning effect based on three types of LED illumination conditions are analyzed. Three factors (learning intention, learning environment, learning motivation) are extracted by ANOVA and there are preference differences of LED illumination conditions between learning intention and learning environment factors. Especially, preference differences of LED illumination conditions are existed about calculation, reading and fatigue reduction. The test results of this study can be applied to obtaining high achievement of learning based on the lighting conditions.

• Journal of the Korean Institute of Educational Facilities
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• v.18 no.2
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• pp.25-33
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• 2011

This study performs the objective evaluation on simple comparison and calculation works by students under LED illumination conditions according to three types of color temperatures (7000K, 5000K, 3000K) in the classroom, Since the objective of this study is to develop an electric lighting conditions suitable for students in the classroom, the learning performance under three types of LED illumination conditions were analyzed. The 4 kinds of simple tests concerning with learning performance were developed and test results under natural light and LED illumination by 3 types of color temperatures were analyzed. There were differences by t-test in most cases among simple experiment results of different illumination conditions ($p{\leq}.05$). It was confirmed that illumination condition plays an important role when students simply compare words or perform arithmetic calculations. The experimental results of this study might be applied to designing better luminous environment.

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

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

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.05a
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• pp.189-192
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• 2006

The development of digital technology makes our life more convenient in our lives and its calmness promotes the qualify of our life. Digital-home-automation system lets indoor-living more free, safe and clear so that it really has come true our life style that considers our mind and healthy to be important. Moreover, LED light source that combines the semiconductor with the digital technology has been tried as a current indoor illumination. Also the introduction of the light which has a high technology, like LED light, has been required in living space. It shows that it is very important to have an illuminated- plan which is accepted as well-developed technology. This study deals with the investigation into the user satisfaction of the existing residential area illumination and the investigation into the user satisfaction of the LED illumination being supplied for commercial area now. In the result, the fact is investigated that the user wants the introduction of the digital technology In the illumination because of a backward the residental area illumination in the circumstances being digital gradually. The inconvenience of the illumination used now should be minimized and the development of the LED illumination is a way satisfying the desire. The intended illumination project of the residential area should be accomplished according to the lifestyle of a changing residence.

• Korean Institute of Interior Design Journal
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• v.14 no.6 s.53
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• pp.220-227
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• 2005

The development of digital technology makes our life more convenient in our lives and its calmness promotes the qualify of our life. Digital-home-automation system lets indoor-living more free, safe and clear so that it really has come true our life style that considers our mind and healthy to be important. Moreover, LED light source that combines the semiconductor with the digital technology has been tried as a current indoor illumination. Also the Introduction of the light which has a high technology, like LED light, has been required in living space. It shows that it is very important to have an illuminated-plan which is accepted as well-developed technology This study deals with the investigation into the user satisfaction of the existing residential area illumination and the investigation Into the user satisfaction of the LED illumination being supplied for commercial area now. In the result, the fact is investigated that the user wants the introduction of the digital technology in the illumination because of a backward the residental area illumination in the circumstances being digital gradually. The inconvenience of the illumination used now should be minimized and the development of the LED illumination is a way satisfying the desire. The intended illumination project of the residential area should be accomplished according to the lifestyle of a changing residence.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1327-1332
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• 2014

This paper presents information about the examples of the design on Illumination of Structures(LED Light Pipe for lighthouse) in Korea. We have applied illumination by flood-lighting or facade-lighting in place of the 57 lighthouses (offshore structures) and 4 beacons. The ways of illumination of structures are using direct illumination with LED, halogen lamps and metal halide lamps, and indirect illumination with LED non-neon lamps. The illumination of structures helps a observer to identify the Aids to Navigation and w aterway. The fabricated LED Light Pipe is a transparent acrylic round bar and easy to install. The Light Pipe is arranged in two rows of L ED (78ea). It can be connected in series. It has 4 colours(Red, Green, Yellow, White). We analyzed and the horizontal divergence angle of the LED light pipe is defined as the range with 50% of maximum luminous intensity. Also, we evaluated the conspicuity on the origin al lantern and LED Light pipe for lighthouse. The field experiment was conducted in 'Yeosuguhang lighthouse' in Yeosu-city (Korea). F rom the experimental results, it was confirmed that the fabricated LED Light Pipe is clearly distinguished.

• Journal of the Korean Institute of Educational Facilities
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• v.20 no.3
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• pp.29-39
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• 2013

This study addresses the evaluation on the satisfaction of school illumination quality by applying SERVPERF model after extracting factors affecting school illumination quality. Three types of illumination systems (fluorescence light, general LED light and high color rendition LED light) were tested by students who have used each illumination system. Three factors such as effectiveness, esthetic sense and function were developed for evaluation. Satisfaction evaluation was performed based on applied SERVPERF model by comparing perceived levels. The differences of perceived levels of satisfaction on the illumination systems were analyzed by ANOVA. The results said respondents satisfy only the high color rendition LED light regardless of three factors. Especially, students who experienced high color rendition LED light have strong intention to recommend that illumination system to other schools. They also express their desire to use that system at home. Interestingly, there is not much satisfaction difference between fluorescence light and general LED light.

• Journal of the Korean Institute of Educational Facilities
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• v.18 no.3
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• pp.23-33
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• 2011

This study investigates the evaluation on simple comparison and seeking hidden figures works under LED illumination conditions according to three types of color temperatures (7000K, 5000K, 3000K) in the classroom, Since the objective of this study is to develop an electric lighting conditions suitable for students in the classroom, the performance of concentration and visual discrimination by students under three types of LED illumination conditions were analyzed. The 4 kinds of simple tests concerning with concentration and 2 types of tests for visual discrimination were developed, and test results under natural light and LED illumination by 3 types of color temperatures were analyzed. There were differences on concentration as well as visual discrimination performance in most cases by t-test ($p{\leq}0.05$). For further analysis among three types of color temperatures and natural light, ANOVA tests were performed. The test results shows that illumination condition plays an important role when students try to concentrate on simple comparison of characters, figures or colors and seek hidden figures. The experimental results of this study might be applied to designing better luminous environment.