• 응용화학
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• 제15권1호
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• pp.17-20
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• 2011

A disposable light exposure detector kit has been developed by UV curing of a hydrogel material. The devised light exposure detector kit consisted of light sensitive structures, bottom plate, character sheet and sticky back plate. A light exposure detector kit has a serial light sensitive structures that contain various light sensitive dyes such as rhodamine and fluorescein. The light sensitive structure composed of UV curable hydrogel polymer material as a supporing material and photosensitive dye in a certain concentration. The fabrication procedure of the ligh exposure detector kit is very simple and fast due to UV curing procedure of a photopolymerizable hydrogel material such as poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) with a photosensitive dye. By the proposed fabrication method, various size and shape of a light exposure detector kit could be fabricated using a flexible elastomer mold. Due to a fast and inexpensive fabrication method, the light exposure detector kit could be use a single use for various industrial applications. According to light irradation, the light sensitive structure on a light exposure detector kit could be lose its color by decomposition of a photosensitive dye chemical in the structure. Thus the amount of the exposed light on a substrate could easily be recognised by changing color or transparency of the structure.

• Journal of Photoscience
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• 제9권2호
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• pp.430-432
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• 2002

The changes in expression of copper-zinc superoxide dismutase (CuZn-SOD), manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase (GPX) in light-damaged rat retinas were examined. Sprague-Dawley rats (male, 6-weeks-old) were maintained on a cyclic photoperiod (12 hours light and 12 hours darkness) for 2 weeks. The illumination intensity during the light period was 80 lux. To induce light damage to the retina, a high-intensity illumination (3000-lux) was applied to the animals for 24 hours. After light exposure, the animals were returned to cyclic lighting. Eyes were enucleated 12 and 24 hours after light exposure started or 1,3, and 7 days after light exposure ended. Eyes were fixed and embedded in paraffin wax. Tissues were cut into 4${\mu}{\textrm}{m}$-thick sections. Sections were immunostained using antibody against CuZn-SOD, Mn-SOD, GPX and 8-hydroxy-deoxyguanocine (8-OHdG) as oxidative stress marker. 8-OHdG was observed in the outer nuclear layer (ONL) and retinal pigment epithelium (RPE) during light exposure. In light-damaged retinas CuZn-SOD labeling was up regulated in the ONL and RPE. Mn-SOD labeling was up regulated in rod inner segments (RIS) during light exposure and that in the RPE was up regulated after exposure. GPX labeling was observed in rod outer segments (ROS) during light exposure. GPX labeling was also observed in the RPE during and after light exposure. All three enzymes were observed in the outer retina, which suffered light damage, but occurred in defferent layers except within the RPE, in which case all three were expressed. These enzymes may play complementary roles as protective factors in light-damaged retinas.

• 수면정신생리
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• 제6권1호
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• pp.68-75
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• 1999

목 적 : 본 연구는 야간 광 노출시 야간교대근무자의 수면양상과 기분상태가 어떠한 변화를 보이는지와 광 노출의 부작용의 정도와 빈도를 알아보고자 하였다. 이런 과정을 통해 광 노출이 야간교대근무적응에 사용될 수 있는지를 밝히고자 하였다. 방 법 : 용인정신병원에 근무하는 야간교대근무 간호사 12명이 본 연구에 참여하였다. 본 연구는 야간근무 대조연구, 야간근무 광노출연구, 주간근무 대조연구의 3부분으로 구성 되었으며 1명의 간호사가 주간근무 대조연구에 참여하지 않은 것을 제외하고는 모든 간호사가 세 연구에 모두 참여하였다. 야간근무 광노출연구시 새벽 1시부터 새벽 5시까지 4시간동안 빛에 노출되었다. 수면양상은 활동기록기와 자동수면 분석프로그램을 통해, 기분상태와 광노출의 부작용은 자기보고척도에 의해 평가하였다. 결 과 : 수면기간시간, 총수면시간, 수면효율은 야간근무 대조연구에 비해 야간근무 광노출연구시 증가되었으며 야간근무 광노출연구는 주간근무 대조연구와 차이를 보이지 않았다. 야간근무 광노출연구시 수면효율의 일간변동도 야간근무 대조연구에 비해 현저하지 않고 안정된 양상을 보였다. 야간근무 광노출연구시 간호사들은 주간수면을 취한 후 저녁시간에 야간근무 대조연구에 비해 좀 더 기분이 고양되고 활기가 넘친다고 보고하였다. 광 노출이 진행되면서 광노출 부작용에 대한 내성이 생겨 부작용의 빈도나 정도가 감소하였으며 광노출 3일째 심한 정도의 부작용을 호소한 사람은 한명도 없었다. 결 론 : 광 노출시 주간수면은 주간근무시의 야간수면만큼 호전되는 것으로 관찰되었고 이러한 수면호전으로 인해 야간교대근무자들은 기분이 고양되고 좀 더 활기가 넘친다고 보고하였다. 광 노출의 부작용도 시간이 지남에 따라 감소하므로 야간교대근무 적응을 위해 광 노출법을 권장할 수 있을 것이다.

• 대한소아치과학회지
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• 제30권2호
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• pp.229-237
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• 2003

본 연구는 기존의 할로겐광(XL 3000, 3M, U.S.A.)과 비교하여 새로운 중합광원인 플라즈마광(Flipo, LOKKI, France)과 Light Emitting Diode(이하 LED, Elipar Free light, 3M, U.S.A.)광의 효율성을 평가할 목적으로 시도되었다. 이에 본 연구에서는 첫째, 일정 광도 하에서 플라즈마광과 LED광의 중합시간에 따른 중합도의 변화를 검토하여 할로겐광의 미세경도와 유사한 광조사 시간을 알아보고, 둘째, 중합반경에 따라 균일한 중합이 이루어지는지를 보기 위해 광조사 부위의 중심부와 외측 변연부에서의 중합도의 차이를 비교하였다. 2mm 두께의 복합레진 시편의 상면과 하면의 미세경도의 측정을 통해 중합도를 평가, 비교해 본 결과 다음과 같은 결론을 얻었다. 1. Z-100의 미세경도 측정치 비교에서, 대조군인 할로겐광을 40초 적용한 경우는, 플라즈마광 6-9초, LED광 40-60초를 적용한 경우와 유사하였다(P>0.05). 2. Tetric Flow의 미세경도에서는 대조군인 할로겐광을 40초 적용한 경우, 플라즈마광 9초, LED광 40-60초를 적용한 경우와 유사하였다(P>0.05). 3. Dyract AP의 경우, 할로겐광 40초를 조사한 것은, 플라즈마광 6-9초, LED광 20-40초를 적용한 경우와 유사하게 나타났다(P>0.05). 4. Fuji II LC에서는 할로겐광을 40초 적용한 경우가, 플라즈마광 9초, LED광 20-60초를 적용한 경우와 유사하게 나타났다(P>0.05). 5. Fuji II LC를 제외한 모든 시료에서 할로겐, 플라즈마, LED광 모두 시편의 중앙에서 외측으로 갈수록 미세경도는 유의하게 감소되었다(p<0.05).

• 센서학회지
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• 제30권2호
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• pp.76-81
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• 2021

In this study, we propose a machine vision system with a high object recognition rate. By utilizing a multiple-exposure image sensing technique, the proposed deep learning-based machine vision system can cover a wide light intensity range without further learning processes on the various light intensity range. If the proposed machine vision system fails to recognize object features, the system operates in a multiple-exposure sensing mode and detects the target object that is blocked in the near dark or bright region. Furthermore, short- and long-exposure images from the multiple-exposure sensing mode are synthesized to obtain accurate object feature information. That results in the generation of a wide dynamic range of image information. Even with the object recognition resources for the deep learning process with a light intensity range of only 23 dB, the prototype machine vision system with the multiple-exposure imaging method demonstrated an object recognition performance with a light intensity range of up to 96 dB.

• 대한치과교정학회지
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• 제34권5호
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• pp.429-438
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• 2004

본 연구는 Plasma arc light를 이용하여 금속 브라켓의 부착시 광조사 방향, 중합시간 그리고 경화시간이 전단결합강도에 미치는 영향을 평가하기 위해서 시행되었다. 240개의 발거된 소구츠를 16군으로 나눈 후. 광중합기(Plasma arc light와 Halogen light), 중합시간(Plasma arc light 2. 4. 6초와 Halogen light 20초). 그리고 광조사 방향(Vertical 방향과 Oblique 방향)을 다르게 하여 브라켓을 부착하였다. 광증합 접착제는 Transbond XT를 이용하였으며 브라켓 부착 후 5분과 24시간 후에 만능물성시험기를 이용하여 전단결합강도를 측정하였다. 결과는 다음과 같다. 광중합기의 종류와 중합시간에 관계없이 Vertical군과 Oblique군간의 전단결합강도는 유의한 차이가 없었다.(p>0.05) Plasma arc light를 이용하여 2초 동안 광중합한 군들의 전단결합강도는 다른 중합시간의 군들보다 현저히 낮았다(P<0.05). 부착 5분 후의 전단결합강도는 24시간 후보다 현저히 낮았다(P<005), ARI 점수는 군들 간에 통계적으로 유의한 차이가 없었다. 이상의 결과는 plasma arc light를 사용한 금속 브라켓의 부착시 광조사 방향은 전단결합강도에 영향을 끼치지 않으며. Halogen light와 유사한 결합강도를 얻기 위해서는 4초 이상의 중합시간이 필요함을 시사한다.

• International Journal of Oral Biology
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• 제34권4호
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• pp.185-190
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• 2009

This study examined the effects of red light generated from a light emitting diode (LED) upon proliferation and mitochondrial stress in human gingival fibroblasts (hGFs). Cells were exposed to LED-generated red light at a clinically relevant intensity and distance with a 610-630 nm wavelength for various times (0-48 min). At different exposure times, cells were processed for the analysis of succinate dehydrogenase (SDH) activity, proliferation, mitochondrial membrane potential (MMP) and cytotoxicity. Cell cycle progression was also investigated by flow cytometry after staining with propidium iodide. Red light exposure was found to inhibit SDH activity and DNA synthesis in hGFs in a time-dependent manner. Light exposure also reduced the MMP levels in these cells and this was closely associated with a $G_0/G_1$ arrest. In contrast, exposure of hGFs to red light for 48 min led to a dramatic loss of MMP with an attendant increase in cytotoxicity. These findings demonstrate that LED-generated red light may cause mitochondrial stress and growth inhibition in hGFs during tooth whitening therapy, depending on the length of the exposure.

• 한국멀티미디어학회논문지
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• 제24권11호
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• pp.1461-1471
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• 2021

This paper presents a light exposure correction algorithm for less pleasant images, acquired with a light metering failure. Since conventional tone mapping and gamma correction methods adopt a function mapping with the same range of input and output, the results are pleasurable for almost symmetric distributions to their intensity average. However, their corrections gave insufficient outputs for asymmetric cases at either bright or dark regions. Also, histogram modification approaches show good results on varied pattern images, but these generate unintentional noises at flat regions because of the compulsive shift of the intensity distribution. Therefore, in order to sufficient corrections for both bright and dark areas, the proposed algorithm calculates the gamma coefficients using primary parameters extracted from the global distribution. And the fusion weights are adaptively determined with complementary parameters, considering the classification information of a binary segmentation. As the result, the proposed algorithm can obtain a good output about both the symmetric and the asymmetric distribution images even with severe exposure values.

• International Journal of Advanced Culture Technology
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• 제9권4호
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• pp.315-319
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• 2021

Recent impact of 4th industrial revolution is increasing usage of IoT technology along with smartphones and tablet PC. However blue light emitted from electronic devices such as smartphones and tablet PC causes detrimental change to human bodies. As the controversy over the harmfulness of blue light became known through the media and various communities, related markets were formed, and various blocking films, software, and vision protection monitors were released. In this paper focuses on utilizing IoT technology to protect human organizations from blue light. It presents anti-blue light system which prevents excessive exposure to blue light through Arduino module such as ultrasound, piezo buzzer and blue light measurement module.

• 수면정신생리
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• 제5권2호
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• pp.170-176
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• 1998

Nowadays light therapy is accepted practice in the treatment for Seasonal Affective Disorder. The author reviewed the practical aspects of light therapy, latest treatment research on optimal parameters of light therapy and the mechanisms of action of light therapy. Therapeutic efficacy of light therapy using light visors & dawn simulators has been suggested but further studies are needed to clarify the efficacy. The treatment most strongly supported by research studies is light therapy using a light box to administer bright white light (2500 lux for 2 hours or 10000 lux for 30 minutes). Although some patients may be selective responders to morning light exposure, the optimal timing of light exposure still remains controversial. In practice, generally the duration of exposure can be increased or decreased as necessary and also the timing of exposure can be splitted (e.g. AM/PM usage) if optimal response is obtained. For most, a positive response of light therapy is usually noted within $4{\sim}5\;days$ and optimal response is obtained within 2 weeks. Generally the relapse of symptom occurs within days of discontinuation of light therapy, so to prevent relapse, light therapy should be continued throughout the winter season for typical seasonal affective disorder. Side effects of light therapy appear to be mild and well tolerated. Several theories for the mechanisms of action of light therapy at the basis of seasonal affective disorder had been suggested but remain still controversial. Further studies on the optimal parameters and the mechanisms of light therapy help us to better understand and treat not only seasonal affective disorders but also chronobiological disorders and nonseasonal affective disorders.