• Design & Manufacturing
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• v.17 no.3
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• pp.8-14
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• 2023

In this study, basic research was conducted on manufacturing technology of thick-walled light guide a component that controls the light source of automobile lamps. As a preliminary study for manufacturing the final injection molded parts, a model for analyzing the influence of micro patterns on light guides is presented. The optical characteristics of the light guide were analyzed according to the change of the curvature radius of the micro-optical pattern, and the injection molding characteristics of the light guide according to the change of injection molding conditions were analytically evaluated. It was confirmed that the luminance uniformity improves as the R value decreases for changes in the micro-pattern R value, but it was confirmed that there are technical limitations in actual injection mold core processing and high-replication injection molding. Injection molding analysis showed that cooling channel design is very important compared to general injection molding due to thick-wall characteristics and thickness variation. It was also confirmed that the cooling channel has a great influence on the cycle time and birefringence result due to residual stress. As a result of analyzing the influence of filling time, holding condition, and cooling on shrinkage, it was found that the cooling water temperature has a significant effect on the shrinkage of ultra-fine light guide parts, and the holding condition also has a significant effect.

• Journal of Plant Biotechnology
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• v.41 no.2
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• pp.94-99
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• 2014

This study was conducted to elucidate the effect of light sources and explant types on in vitro shoot multiplication and rooting of a rare and endangered plant Abeliophyllum distichum. Both apical buds and axillary buds were used as explants under 4 different light sources, cool white florescent light (F), 100% blue light-emitting diode (LED) (B), 50% blue and 50% red LED mixture (BR), and 100% red LED (R). Clear difference was observed in terms of shoot proliferation by light sources types but not by position-dependent explant types. Multiple shoot induction rates were enhanced under both B and BR light sources. Spontaneous rooting was induced in shoot induction medium under B light source. Both the rates of rooting and numbers of roots per explant were higher in apical bud explants compared to axillary bud explants. Interestingly R light source stimulated shoot elongation but inhibited root development. Therefore, our results suggest that the use of apical bud explants under B or BR light sources is suitable for in vitro micropropagation of a rare and endangered plant species, Abeliophyllum distichum.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.226-229
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• 2010

Many methods exist that promote wound healing, including light therapy, which consists of light beams that assist the human body in treating and sterilizing wounds, as well as regenerating cells. Irradiation with specific wavelengths of either laser or LED light has been shown to induce beneficial proliferation of fibroblasts that, depending on the size of the wound, can be effective in promoting wound healing. The experiments in this study utilized 8 week old 250~300 g Male Sprague Dawley Rats (ILAR Code: NTacSam:SD) and included a non-irradiation group and a 525 nm green LED irradiation group (n of each group = 7). In experiments animals were allowed to rest for 24 hours after wounds had been excised, which was followed by non- irradiation or 525 nm green LED irradiation therapy one hour per day for 9 days. Immunohistochemical staining was conducted for cytokeratin in order to precisely measure the defect size. In addition, Masson's trichrome staining was utilized in order to compare levels of collagen between the 525 nm green LED irradiation group and the non-irradiation group. Animals exposed to 525 nm green LED irradiation (p<0.05) healed at a faster rate and had increased collagenosis compared with the non-irradiated control group. Thus, treatment with 525 nm green LED irradiation had a beneficial effect on wound healing and should be considered as a possible alternative to low power laser treatment.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.272-274
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• 2002

The contribution of light in high-energy film dosimetry was examined using six commercially available solid water substitute phantoms. As six commercially available phantoms; RMI-451, Mix-DP, WE211, WE211-Black, PMMA and PMMA Black were evaluated in this study. It is difficult to evaluate the contribution of Cerenkov radiation and the optical permeability to the relative and/or absolute dosimetry using unpacked film in these phantoms. Therefore the contribution of Cerenkov radiation was estimated by the comparison between film densities in the shielded side (shutting off the light) and unshielded sides on a phantom. The effect of optical permeability was measured under ambient light by the time scale method. The results suggest that the use of black colored phantoms may improve the accuracy of dose measurement in film dosimetry.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.1
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• pp.110-115
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• 2004

This experiment was conducted to investigate the effect of light intensities on the growth responses, carbohydrate contents and the characteristics of leaf gas exchange in Miscanthus sinensis and Pennisetum purpurascens. The plant height and leaf length were increased to about 30% in the sun. However, those were reduced severely in the shade, and leaf necrosis was also observed. The representative growth index and the dry weight of 2 species were 50% higher than shade and the rate was reduced according to the decrease of light intensities. Total carbohydrate contents showed very similar changes to that of dry weight. However, any notable influences were observed at above the light intensities of 250~500${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ in the half shade. The size of spikes and the earliest spiking appeared in the sun and the spike color was decolorized as decreased in light intensities, irrespective of species. Photosynthetic rate of 2 species was 2 times higher in the sun than those in the shade, and it showed the typical photoresponses of sun plant. Stomatal conductances and intercelluar $CO_2$ concetration showed similar changes to that of photosynthetic rate. On the contrary, vapor pressure deficit was increased more in the shade than in the sun.

• Journal of the Semiconductor & Display Technology
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• v.13 no.2
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• pp.37-44
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• 2014

In this study, the performance of dye-sensitized solar cells with different thickness of the photelectrode film was simulated by using the electron-diffusion differential model. Through this simulation, the relationships between the thickness of the photoelectrode film and the performances (open-circuit voltage, short-circuit current density, and overall photoelectric-conversion efficiency) of cells were understood and the performances with different thickness of the photoelectrede film were also examined. For considering the refractive index in the liquid electrolyte and exploring the scattering effect of titanium dioxide particles with different sizes using the Mie light-scattering theory, the highest scattering effect of each particles was found out and the optimal size of the titanium dioxide particle was determined for light scattering in the photoelectrode film of dye-sensitized solar cell. Through experiment, the mixed titanium dioxide cell was better than the single titanium dioxide cell and generated a higher overall conversion efficiency because the optimal titanium dioxide particles in the phoelectrode film as light scattering.

• Korean journal of food and cookery science
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• v.22 no.6 s.96
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• pp.783-791
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• 2006

The consciousness and eating habits of the housekeeper directly influence the stress level and health quality of the household occupants. In Korea, most housewives are in charge of dietary life. Accordingly, their attitudinal clusters toward dietary (eating) life were researched in relation to their stress and health. The research results showed that irregular eating habits cause stress. Therefore, it is necessary for housewives to have a regular eating habit. The results were as follows. The house wives' attitudes toward dietary life were categorized into 5 clusters: regular and speedy overeating, regular and frequent eating, regular and light eating, irregular and light eating, irregular and speedy overeating. The cluster of regular and frequent snacks was 24.3%. The cluster of irregular and speedy overeating caused the most stress. Especially the house wives' group belonging to the cluster of irregular and speedy overeating were under social and emotional stress, while the cluster of regular and light eating and the cluster of irregular and light eating were under concentration stress. The cluster of regular and frequent snacks and the cluster of irregular and light eating had negative effect on their health, while the cluster of regular and speedy overeating had negative effect on their family's health by their social stress.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.2
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• pp.123-133
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• 2020

Four LEDs (blue, green, red, and white light) were tested to identify the most attractive wave length to utilize as the forecasting tools for the B. tabaci in glass houses. Attractiveness was evaluated by the total number of the B. tabaci attached to a yellow sticky trap. In the condition of no host plant supplement, the attraction efficacy was ordered from high to low as blue light (107.3±2.5), white light (83.0±12.1), red light (58±21.8), and green light (39.7±8.1). In the supplement of the host plant, the attraction was observed in the order of blue light (52±17.4), red light (38.7±5.8), green light (12.7±1.5), and white light (11.7±5.0). In both experimental conditions, blue light showed the highest attraction. In terms of the host plant effect to LED attraction, it varied following as white light (85.9%), green light (68.1%), blue light (51.6%), and red light (33.3%). This result suggests that red light is the least affected by the host plant. In the evaluation of the relative control efficacy, it was determined following as red light (66.7%), blue light (48.5%), green light (31.9%) and white light (14.1%) (F_3,8 = 14.7, P = 0.001). Taken together, blue light had a very high initial attraction, and red light was revealed low attraction effect by the supplement of the host plant. In field demonstration experiments, a high attractive efficacy was not observed due to low-temperature conditions, but similar higher attractive efficacy was observed in blue and red lights compared to the control. The commercialization of LEDs using red and blue in the future is expected to provide important information regarding B. tabaci population density forecast in glass house.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.3
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• pp.365-371
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• 2001

The effects of light exposure and light intensity on surface color of Hanwoo (Korean native cattle) beef and color stability of fresh normal and DFD (dark, firm, dry) muscles during 7 days at $4{\pm}1^{\circ}C$ under three display conditions (Dark, Light1000 and Light3000) were investigated. The $L^*$, $a^*$, $b^*$, $C^*$ values and R630-R580 were significantly (p<0.05) higher in normal beef than in DFD beef. The $a^*$, $b^*$, $c^*$ values and R630-R580 of normal beef increased during the first day of display except Light3000 group, then gradually decreased over time. The surfaces of Hanwoo beef accumulated more metmyoglobin in the light than in the dark. Also, the rate of decrease in redness during refrigerated storage was enhanced by light exposure and increase in light intensity. Discolorations were more rapid in DFD beef than normal beef. Increasing light intensity promoted not only discoloration but also lipid oxidation. Therefore storage in the dark is effective in retarding the formation of a brown color in Hanwoo beef.

• KSBB Journal
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• v.19 no.4
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• pp.257-262
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• 2004

Recently, there is a growing interest in microalgae and the use of microalgae focused on the production of various high value metabolite used in food, pharmaceuticals and cosmetics. The key limiting factor in high density algal cultivation is the light and algal growth is defined by light intensity and light penetration depth into the culture medium. The effect of light with various light paths, S/V ratios, light intensities, and 50% duty cycle on the growth of microalgae was examined to enhance microalgal biomass productivity and photosynthetic efficiency. We confirmed that the utilization of efficient light energy was obtained from 4 cm of diameter, 57.6% of S/V ratio, 62 ${\mu}$mol/㎡/s of light intensity.