• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.233-239
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• 2016

Color enhancement basically deals with color manipulation in digital images. Recently, the technique has become widely used as a result of the increasing use of digital cameras. Retinex-based colorenhancement algorithms are a popular technique. In this paper, retinex with bilateral filtering is proposed to improve the quality of poorly illuminated images. Generally, it consists of three main steps: first, a retinex-based algorithm with color restoration; second, transformation mapping using histogram matching; and finally, smoothing the image using a bilateral filter. The experimental results demonstrate that the proposed method can successfully enhance image contrast while avoiding the halo effect and maintaining the color distribution in the image.

• 조명전기설비학회논문지
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• 제23권4호
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• pp.1-7
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• 2009

본 연구에서는 농촌 청소년 공부방을 대상으로 조명환경 실태조사를 실시하였다. 그 결과, 공부방의 평균 공간의 크기는 11.42[$m^2$]이며, 주로 광원은 형광등을 사용하였으며 조명사용방법은 전반조명만 이용하는 경우가 73.8[%]이며, 배광방식은 직접조명 방식을 주로 사용하고 있었다. 또한 스탠드를 소유하고 있는 가구는 45.7[%]이었으며, 국부조명인 스탠드를 사용하는 비율은 전체 조사대상의 20[%]에 지나지 않아 시작업이 효과적이지 못하였다. 내부공간 조도는 평균 131.82[lx]이며, 책상면 조도는 253.64[lx]로 최저허용조도의 42.3[%]에 해당하는 열악한 실정이었으며, 균제도는 평균 35.61[%]로 나타났다. 또한 사용자의 조명환경에 비해 만족도는 3.93점으로 높아 조명에 대한 인식이 매우 부족한 것으로 사료된다.

• 한국멀티미디어학회논문지
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• 제25권8호
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• pp.991-998
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• 2022

Recently, object recognition using image/video signals is rapidly spreading on autonomous driving and mobile phones. However, the actual input image/video signals are easily exposed to a poor illuminance environment. A recent researches for improving illumination enable to estimate and compensate the illumination parameters. In this study, we propose VE-DCE (video enhancement zero-reference deep curve estimation) to improve the illumination of low-light images. The proposed VE-DCE uses unsupervised learning-based zero-reference deep curve, which is one of the latest among learning based estimation techniques. Experimental results show that the proposed method can achieve the quality of low-light video as well as images compared to the previous method. In addition, it can reduce the computational complexity with respect to the existing method.

• 조명전기설비학회논문지
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• 제19권7호
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• pp.9-14
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• 2005

본 연구에서는 단독주택 공부방을 대상으로 조명환경 실태조사를 실시하였다. 그 결과, 공부방은 주로 형광등을 사용하였으며 배광방식은 직접조명 방식을 사용하고 있었다. 또한 국부조명을 사용하는 비율은 48.2[%]로 시작업이 효과적이지 못하였다. 내부공간 조도는 평균 131.41[lx]이며, 책상면 조도는 322.57[lx]로 최저허용조도의 54[%]에 해당하는 열악한 실정이었다. 또한 사용자의 조명환경에 비해 만족도는 높아 조명에 대한 인식이 매우 부족한 것으로 사료된다.

• Journal of Biosystems Engineering
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• 제35권2호
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• pp.124-131
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• 2010

Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research has demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.247-255
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• 2012

Daylighting has a very effective role in reducing power consumption and improving indoor environments in office buildings. Previously, it was not under consideration as a major source of renewable energy due to poor reliability in the design. Optical fiber as a transmission medium in the daylighting system demands uniform distribution of light to solve cost, heat, and efficiency issues. Therefore, this study focuses on the uniform distribution of sunlight through the fiber bundle and to the interior of the building. To this end, two efficient approaches for the fiber-based daylighting system are presented. The first approach consists of a parabolic mirror, and the second approach contains a Fresnel lens. Sunlight is captured, guided, and distributed through the concentrator, optical fibers, and lenses, respectively. At the capturing stage, uniform illumination solves the heat problem, which has critical importance in making the system cost-effective by introducing plastic optical fibers. The efficiency of the system is increased by collimated light, which helps to insert maximum light into the optical fibers. Furthermore, we find that the hybrid system of combining sunlight and light emitting diode light gives better illumination levels than that of traditional lighting systems. Simulation and experimental results have shown that the efficiency of the system is better than previous fiber-based daylighting systems.

• International Journal of Control, Automation, and Systems
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• 제6권5호
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• pp.746-754
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• 2008

This paper proposes a method to detect calibration patterns for accurate camera calibration under complicated backgrounds and uneven lighting conditions of industrial fields. Required to measure object dimensions, the preprocessing of camera calibration must be able to extract calibration points from a calibration pattern. However, industrial fields for visual inspection rarely provide the proper lighting conditions for camera calibration of a measurement system. In this paper, a probabilistic criterion is proposed to detect a local set of calibration points, which would guide the extraction of other calibration points in a cluttered background under irregular lighting conditions. If only a local part of the calibration pattern can be seen, input data can be extracted for camera calibration. In an experiment using real images, we verified that the method can be applied to camera calibration for poor quality images obtained under uneven illumination and cluttered background.

• ETRI Journal
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• 제37권4호
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• pp.677-684
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• 2015

Recently, orthogonal frequency-division multiplexing (OFDM) was applied to VLC systems owing to its high rate capability. On the other hand, a real-valued unipolar OFDM signal for VLC significantly reduces bandwidth efficiency. For practical implementation, channel estimation is required for data demodulation, which causes a further decrease in spectral efficiency. In addition, the large fluctuation of an OFDM signal results in poor illumination quality, such as chromaticity changes. This paper proposes a spectrally efficient method based on a hidden-pilot-aided precoding technology for VLC with less flickering than a conventional OFDM-based method. This approach can obtain channel information without any loss of bandwidth efficiency while ensuring illumination quality by reducing the flickering effect of an OFDM-based VLC. The simulation results show that the proposed method provides a 6.4% gain in bandwidth efficiency with a 4% reduction in flicker compared to a conventional OFDM-based method.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 추계학술대회
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• pp.239-240
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• 2013

The quality of document images captured by digital camera might be degraded because of non-uniform illumination condition. The high illumination (glare distortion) affects on the contrast condition of the document images. This condition leads to the poor contrast condition of the text in document image. So, optical character recognition (OCR) system might hardly recognize text in the high illuminated area. The method to increase the contrast condition between text (foreground) and background in high illuminated area is proposed in this paper.

• Journal of Preventive Medicine and Public Health
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• 제29권1호
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• pp.1-14
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• 1996

한 종합병원의 작업환경에 존재하는 건강저해인자를 평가함으로써 종사원들의 건강보호와 작업능률 향상에 기여하고자 조사연구를 실시하였다. 병원건물의 구조와 업무내용으로 보아 작업환경의 대표가 될 것으로 보이는 27개 부서를 선정하여 1993년 10월부터 1994년 10월까지 작업환경에 대한 종사원의 설문과 현장조사 및 측정을 실시하였다. 설문을 통하여 종사원들이 느끼는 건강저해인자에의 노출상태를 양호(A), 보통(B), 미흡(C), 불량(C)로 분류하고, 현장조사와 측정에 의한 각 인자의 노출상태를 양호(a), 보통(b), 미흡(c),불량(d)으로 분류하여 노출되고 있는 종사원의 분포를 검토한 결과는 다음과 같다. 1. 작업환경 측정결과 조도는 전체대상자 240명의 근로자 중 c등급 이하의 전반조도에 노출된 종사원은 86명(36%), c등급 이하의 국소조도에 노출된 종사자는 193명(80%)이었고, 온열조건에 관한 측정결과 c등급 이하의 환경에의 노출자가 34명(14%), c등급 이하의 소음환경에 180명(75%)이 노출되고 있었다. 공기 중의 먼지량과 톨루엔의 측정결과 c등급 이하의 환경에 노출된 사람은 없었으며, 외부의 자료와 노출상태를 조사한 결과 방사선과 항암제/항생제에 의한 c등급 이하의 환경에의 노출자도 없는 것으로 평가되었다. 2. 건강저해인자에 대하여 종사원이 느끼는 노출 정도(A, B, C, D등급)와 현장조사와 측정으로 확인된 노출 정도(a, b, c, d 등급)는 차이가 많아서, 특히 조도에서는 종사원이 저해환경을 과소평가하고, 공기 중 먼지에서는 과대평가가 심했으며, 온열조건, 소음, 방사선, 톨루엔, 항암제, 항생제에의 노출은 조사된 결과보다 나쁘게 느끼는 경향이 있었다. 3.설문에서 호소하는 소음의 증류로는 사람 말소리가 179명, 실내장비소리가 131명의 순이었으며, 실내공기 중 먼지의 종류로는 사람들의 옷먼지 108명, 건물먼지 79명의 순으로 많았다. 4. 설문에서 C등급 이하의 마취제에의 노출자가 28명, 알칼리/산에의 노출자가 10명, 약진에의 노출자가 6명이었으나 이들에 대한 측정이 불가능하여 평가할 수 없었다.