• 교육시설 논문지
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• 제20권3호
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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.

• 한국콘텐츠학회논문지
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• 제9권12호
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• pp.10-18
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• 2009

일반적으로 PDA, 모바일 폰 카메라, PC 카메라 등으로 촬영된 영상은 촬영 장비의 생동 폭의 한계로 인해 낮은 영상 대비를 갖는 영상들이 획득된다. 이러한 이유로 영상 개선 방법은 여러 가지의 영상 촬영 장비를 이용해 촬영된 영상들의 개선을 위해 필요하다. 영상 개선을 위한 몇 가지의 방법들이 제안되었으나, 후광효과(halo-artifact), 회색계의 왜곡(graying-out), 칼라 잡음(color noise) 등의 영상 왜곡이 발생한다. 이러한 문제를 해결하기 위해, 본 논문은 레티넥스 기반 영상 향상 방법을 제안하며, 회색계의 왜곡을 줄이기 위해 HSV 칼라 좌표계를 사용하며, 후광효과를 줄이기 위해 영상을 전역조명성분, 국부조명성분, 반사성분으로 나누는 개선된 영상 생성모델을 적용한다. 실험 결과는 제안한 방법이 다른 방법들 보다 성능이 우수함을 보여준다.

• 한국광학회지
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• 제6권4호
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• pp.266-273
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• 1995

칼라영상센서의 분광감응 특성은 칼라영상의 색을 결정하는 중요한 요인이 된다. 칼라영상센서의 분광특성을 간편하게 측정할 수 있는 장치를 제작하고 이를 사용하여 CCD 칼라 카메라의 분광특성을 조사하였다. 측정장치는 가시광선 영역내에서 단색광의 파장뿐만아니라 세기도 간편하게 조절할 수 있도록 제작된 광학부와 칼라영상센서의 출력신호를 디지탈값으로 처리하여 나타내는 색분석부로 구성되었다. 광학부에서 만들어진 단색광들에 대한 카메라의 출력값 R, G, B를 측정하였으며 이로부터 카메라의 연색성 및 선형성을 평가하였다. 이로써 제작된 측정장치가 칼라영상센서의 분광특성 측정 및 성능평가에 매우 유용함을 확인할 수 있었다.

• 터널과지하공간
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• 제12권1호
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• pp.1-9
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• 2002

최근 암반공학 분야에서 영상분석기법 및 상용 영상분석장비의 활용이 활발히 이루어지는 추세이다. 그러나 영상의 획득 및 분석 단계에서 발생 가능한 오차들의 문제에 대해서 많은 부분 무시되어 왔으며 관련 연구 또한 미비하였다. 객관적인 암석영상의 분석 및 신뢰도 향상을 위해서는 암석영상에 적합한 컬러보정기법의 마련이 필요하다. 이에 본 연구에서는 암석영상에 대하여 표준컬러차트를 이용한 컬러보정기법을 도입하였으며, 화강암 시료를 대상으로 획득된 영상에 대하여 컬러보정과 오차분석을 수행하였다. 그 결과 암석영상들간의 상호 비교분석이 가능하였으며 또한 영상 획득 및 분석 단계의 신뢰도 향상을 꾀할 수 있었다.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.102-111
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• 2015

This paper proposes an algorithm for recovering the colors of objects from multiple near-infrared (near-IR) images. The International Commission on Illumination (CIE) color coordinates of objects are recovered from a series of gray images captured under multiple spectral near-IR illuminations using polynomial regression. The feasibility of the proposed algorithm is tested experimentally by using 24 color patches of the Color Rendition Chart. The experimental apparatus is composed of a monochrome digital camera without an IR cut-off filter and a custom-designed LED illuminator emitting multiple spectral near-IR illuminations, with peak wavelengths near the red edge of the visible band, namely at 700, 740, 780, and 860 nm. The average color difference between the original and the recovered colors for all 24 patches was found to be 11.1. However, if some particular patches with high value are disregarded, the average color difference is reduced to 4.2, and this value is within the acceptability tolerance for complex image on the display.

• 한국인터넷방송통신학회논문지
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• 제11권4호
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• pp.223-229
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• 2011

본 연구에서는 방송 촬영용 LED Spot 조명기기를 두 가지 형태로 개발하여, 현재 방송용 스튜디오 조명기기가 설치되어 있는 공간에서 다수 사용되고 있는 영국의 Arri사 650W와 1000W Fresnel Spot 조명기기와 조도, 색온도, 연색성 등의 비교 데이터 측정과 피사체의 촬영 시 영상 및 연색성에 따른 색상을 비교 측정하였다. 그리고 방송 촬영용으로 LED Spot 조명기기가 대체 가능한지를 판단하기 위하여 성능평가분석 하였다. 실험평가에서 할로겐 조명기기의 대체용으로 LED Spot 조명기기의 가능성을 확인하였다.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.27-34
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• 2015

There has been a critical issue in optical simulation of phosphors in LEDs due to their light-reabsorption properties. To improve the accuracy of optical modeling for a white LED package, we utilized the spectrum data of the phosphor-dispersed encapsulant film instead of the phosphor powder. By measuring white LED packages with green and red phosphors, the maximum difference between simulation and experimental results of a color temperature, a color rendition index number and a color coordinate corresponds to ${\Delta}T=95K$, ${\Delta}Ra=1.7$ and ${\Delta}xy=0.007$, respectively. Based on those results, the proposed method can well explain the change of emission spectra of white LEDs with more than two phosphors which introduce the complex optical phenomena such as absorption, reabsorption, light emission, reflection and scattering, etc.

• Transactions on Electrical and Electronic Materials
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• 제15권2호
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• pp.69-72
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• 2014

White LEDs, based on blue LED chips coated with a yellow emitting phosphor (YAG:Ce), have several disadvantages. In this paper, we report the improvement in CRI [Color Rendition Index] using $GdAl_5O_{12}:Ce$ (GdAG:Ce) and related phosphors for blue LEDs. A modified combustion synthesis route using mixed fuel was used for synthesis route. By using this procedure, we formed the desired compounds in a single step. LEDs were then fabricated by coating the blue LED chips (CREE 470 nm, 300 micron) with the GdAG:Ce phosphor dispersed in epoxy resin. The CRI typically between 65~70 for the YAG:Ce based LED was improved to 87 for LEDs fabricated from the Gd(Al,Ga)G phosphors.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권10호
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• pp.530-535
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• 2001

Resonant-type electronic ballast for a metal halide discharge(MHD) lamp is proposed and implemented for 400W MHD lamp. HID lamps have good color rendition, long life and good focusing capability but they have flickers by acoustic resonance when driven at high frequency. A new control method is employed to remove acoustic resonance related instability in HID lamp. By using the amplitude modulation, a spread spectrum effect is employed on the ballast. The control loop of resonant inverter is analyzed and a current is designed. The ballast consists of a power factor controller, an half-bridge resonant inverter, a simple ignitor and an integrator with OP-amps. The experimental results show the good performance as PF 0.93, ballast loss 22W at output 400W and the conducted EMI level is below 60dBuV.

• 한국디지털건축인테리어학회논문집
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• 제11권3호
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• pp.61-67
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• 2011

This study examined the P Church in the Large chapel and S Church in the midium chapel were Analyzed to the installed stage broadcast lighting system. As a result of the installation of lighting equipment of LED class in P Church in the Large chapel, it provided clearer image and did not have shadow. While tungsten halogen illumination was very hot and heated to be preaching, LED was not heated so the pastor was very comfortable for preaching. S Church in the Midium chapel due to low ceiling height using LED lighting musical, theater and possibly were directed. If a similar structure of Dae-Hak Street theater to replace the existing fixtures by LED lighting, rendering effective and energy saving effect is thought to have much effect.