• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.147-148
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• 2009

We have fabricated a down tapered polymer tip on optical fiber end-face by a guided UV light. One side of fiber was aligned with a mercury-xenon lamp and another was put into UV curable polymer. A shape of tip was controlled by adjusting an irradiance of lamp and time of exposure. A bending effect also affects the result. Optical characteristic was achieved preliminarily with solution of minute particles.

• Journal of Powder Materials
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• v.26 no.4
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• pp.327-333
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• 2019

In this study, a process is developed for 3D printing with alumina ($Al_2O_3$). First, a photocurable slurry made from nanoparticle $Al_2O_3$ powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of $Al_2O_3$ is determined by measuring the rheological properties of the slurry. Then, green bodies of $Al_2O_3$ with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed $Al_2O_3$ green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that $Al_2O_3$ products of various sizes and shapes can be fabricated by DLP 3D printing.

• IEIE Transactions on Smart Processing and Computing
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• v.1 no.1
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• pp.8-16
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• 2012

An image obtained from a low light environment results in a low-exposure problem caused by non-ideal camera settings, i.e. aperture size and shutter speed. Of particular note, the multiple color-filter aperture (MCA) system inherently suffers from low-exposure problems and performance degradation in its image classification and registration processes due to its finite size of the apertures. In this context, this paper presents a novel method for the color enhancement of low-exposure images and its application to color shift model-based MCA system for image refocusing. Although various histogram equalization (HE) approaches have been proposed, they tend to distort the color information of the processed image due to the range limits of the histogram. The proposed color enhancement algorithm enhances the global brightness by analyzing the basic cause of the low-exposure phenomenon, and then compensates for the contrast degradation artifacts by using an adaptive histogram specification. We also apply the proposed algorithm to the preprocessing step of the refocusing technique in the MCA system to enhance the color image. The experimental results confirm that the proposed method can enhance the contrast of any low-exposure color image acquired by a conventional camera, and is suitable for commercial low-cost, high-quality imaging devices, such as consumer-grade camcorders, real-time 3D reconstruction systems, digital, and computational cameras.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.145-152
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• 1984

The purpose of this study was to compare combinations of the four visible light irradiating appliances (Translux, Heliomat, Pluraflex HL 150, Omega) and the four visible light activated composite resins (Durafil, Heliosit, Plurafil-super, Silux) to determine the depth of polymerization of each combination. Twenty samples were made with Durafil. Five samples were polymerized for 20 seconds using Translux, five with Heliomat, five with Pluraflex HL 150, five with Omega. Twenty samples were made with Heliosit, twenty with Plurafil-super, and twenty samples with Silux. A 20-second polymerization time was applied with each of 4 visible light irradiating appliances to 5 samples of each material. Eighty samples were treated in a like manner, but polymerization was extended to 40 seconds. Depth of polymerization were measured with caliper. The results were as follows. 1) Of the two time exposures, 40-second exposure provided a significantly greater depth of polymerization than 20-second for each light with each material. 2) Durafill-Translux system showed minimum depth of polymerization, and Plurafil-Pluraflex system showed maximum depth of polymerization. 3) Visible light irradiating appliances were able to harden the resins cured by tire visible lights of other makers' apparatuses. 4) In all circumstances, depth of polymerization was between 3.0-3.8mm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.770-775
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• 2000

A new photo-polymer material of the copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy)chalcone-cholesteryl methacrylate) for homeotropic alignment was synthesized and the electro-optical (EO) performance for the photo-aligned vertical-aligned (VA)-LC display (LCD) was studied. Good thermal stabilities of synthesized copolymer were obtained by TGA(Thermogravimetric Analysis) measurement. Good voltage-transmittance (V-T) and response time characteristics for the photo-aligned VA-LCD with polarized UV exposure in oblique direction($\theta$$_{i}$=30$^{\circ}$) on a copolymer-1 (2%) surfaces for 1 min were observed. but, light leakage in the off-state was observed. Therefore, we achieved excellent V-T and response time characteristics for the photo-aligned VA-LCD with UV exposure on a copolymer-3 (30%) surfaces for 3 min.n.

• Macromolecular Research
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• v.10 no.3
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• pp.168-173
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• 2002

Unstabilized low-density polyethylene (LDPE) films and films formulated with hindered amine light stabilizer (HALS) were exposed to UV-radiation; and the physicochemical changes during photooxidation processes have been investigated using tensile, FTIR spectre-photometric and thermal analytical (DSC) techniques. The dependence of tensile properties (elongation- and stress-at-break), carboxyl index and heat of fusion on UV-irradiation time have been discussed. The use of HALS is found to be effective in maintaining the UV-mechanical properties of the LDPE films. The experimental results showed that there exists no correlation between mechanical properties and carbonyl index, whereas crystallinity correlates well with carbonyl index in unstabilized and stabilized films for irradiation times greater than 100 h. The rate of formation of carbonyl groups is found to be dependent on UV exposure time. Crystallinity of the film samples is strongly influenced by both exposure time and presence of HALS.

• Journal of the Korean Home Economics Association
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• v.46 no.10
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• pp.1-9
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• 2008

The purpose of this study was to increase uv-cut ability of cotton, ramie, and rayon fabrics dyed with safflower red colorants. For this purpose, samples treated with uv-cut agent and tannic acid were compared with the untreated samples after ultraviolet(uv)-light exposure in terms of K/S value, color changes(${\Delta}E$), SEM, and tensile strength retention. K/S value rapidly decreased with increasing exposure time, but K/S value of the samples treated with both uv-cut agent and tannic acid decreased less than that of untreated samples. As increasing exposure time, $L^*$ and $b^*$ increased, $a^*$ decreased, and so ${\Delta}E$ increased, indicating less red character and more yellow character in color. This leads to change hue, value and chroma value. But color change of samples treated with both uv-cut agent and tannic acid was less than that of untreated samples. SEM pictures showed a severe degradation by uv exposure in all samples. Tensile strength slowly decreased for 21 days. And after this point, the decreased proceeded more rapidly. Tensile strength retention of the samples treated with uv-cut agent and tannic acid was higher than that of untreated samples.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.140-146
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• 2001

In order to analyze the photodegradation of plastic materials for floats or frames of fisheries facilities, weathering experiment on 3 kinds of plastic materials like high density PE of Korea(KHDPE) and Norway(NHDPE) and high strength PVC(Hi-PVC) was carried out during 900 hours exposure by using xenon light source of weather-Ometer. The results obtained are as follows; With increasing of ultraviolet radiation(UVR) time, a remarkable losses in the mechanical properties of each specimen were observed except for the remaining strain of HDPE materials. As NHDPE lost almost 15% of its initial tensile stress during a 900 hours exposure followed by KHDPE 12% and Hi-PVC 6%. In addition, the remaining tensile stress RS(kg/$mm^2$) decreases almost linearly with the lapse of exposure time to light Y(Year) and the empirical equations of each specimen computed as follows; KHDPE : RS=2.6769-0.0003Y($r^2$=0.63) Hi-PVC : RS=5.3470-0.0003Y($r^2$=0.91) NHDPE : RS=2.4929-0.0004Y($r^2$=0.97) It was observed by scanning electron microscope that all specimens with UVR time had started to decompose and had bubbled areas and small holes.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.2
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• pp.106-111
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• 2018

Recently, due to the effect of global warming, the high temperature phenomenon continues, and the time for workers exposed to high temperature, cold and infrared is increasing and then safety is threatened. Due to the nature of on-site work, the work is being carried out in an unreasonable manner due to the process, which is exposed to disasters due to high temperature and cold. Even though the injured skin may be damaged, the worker may not be aware of it and may be injured. By understanding the working environment of the worker and calculating the risk index and expressing it on the helmet, the surrounding colleagues inform the worker of the risk and take appropriate measures so that the accident can be prevented in advance. This study was conducted to investigate the effect of exposure duration on the workers' by measuring the exposure time, the risk index is displayed in the form of a traffic light to the helm, informing neighboring workers and managers, and transmitting to the workers by voice.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.228-234
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• 2023

In this study, the performance of a gold biosensor combined with light microscope imaging system (GB-LMIS) was comparatively evaluated against enzyme-linked immunosorbent assay (ELISA) for detecting Salmonella under simulated chilling condition. The optimum concentration of antiSalmonella polyclonal antibodies (pAbs) was determined to be 12.5 and 100 ㎍/ml for ELISA and GBLMIS, respectively. GB-LMIS exhibited a sufficient and competitive specificity toward three tested Salmonella among only. To mimic a real-world situation, chicken was inoculated with Salmonella cocktail and stored under chilling condition for 48 h. The overall growth of Salmonella under chilling condition was significantly lower than that under non-exposure to the chilling condition (p < 0.05). No significant differences in bacterial growth were observed between brain heart infusion and brilliant green broth during the enrichment period (p > 0.05). Finally, both GB-LMIS and ELISA were employed to detect Salmonella at every 2-h interval. GB-LMIS detected Salmonella with a competitive specificity by the direct observation of bacteria on the sensor using a charge-coupled device camera within a detection time of ~2.5 h. GB-LMIS is a feasible, novel, and rapid method for detecting Salmonella in poultry facilities.