• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.1
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• pp.71-85
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• 1993

The purpose of the study was to investigate the effects of the single and fractionated irradiation on the microvascular structure of the submandibular gland in rats. For this study, 90 Sprague-Dawley strain rats were irradiated to their neck region with equal split doses of 9Gy for a 4 hours interval and 15Gy single dose by 6MV X-irradiation and sacrificed on the 1st, 3rd, 7th, 14th and 27th day after irradiation. The author observed histological changes at Hematoxylin and Eosin staining and PAS staining under a light microscope, and also observed distribution and structural changes of the microvasculature in rat submandibular gland using a scanning electron microscope by forming vascular resin casting. The results were as follows: 1. In the light microscopic examination, the microvasculature was slightly dilated and decreased in number on the 1st day after irradiation, and increase in number of microvasculature was observed on the 3rd day after irradiation. And then distribution of microvasculature was markedly increased on the 7th day after iradiation, but decreased on th 14th day after irradiation again. Such changes were greater in the single irradiated group than in the fractionated irradiated group. 2. The reaction to PAS staining on glandular cell was decreased on the 1st and the 3rd day after irradiation, and recovered on the 7th day after irradiation. The reaction was decreased on the 14th day after irradiation again, and recovered on the 28th day after irradiation. Changes were more apparent in the single irradiated group. 3. In the scanning electron microscopic examination, early changes of microvasculature were decreased capillary density, dilation of conduits and meandering. Increased capillary dentsity or anastomosis due to vascular reproduction and smooth curved running were observed on the 7th and 14th day after irradiation. Decreased capillary and smooth running tendency were observed on the 28th day after irradiation again. Such changes were greater in the single irradiated group than in the fractionated irradiated group.

• Korean Journal of Food Science and Technology
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• v.4 no.4
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• pp.259-264
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• 1972

Oxidative changes of the Ramyon lipids were studied under three experimental storage conditions. Ramyon was 1) exposed to fluorescent light irradiation at $25^{\circ}C$, 2) incubated in the dark at $40^{\circ}C$ and 3) irradiated with ultra-violet light at $25^{\circ}C$. In the study, changes in acid value, peroxide value, carbonyl value, TBA number, fatty acid composition and iodine value were determined with the lipids extracted from the Ramyon samples in intervals for a period of 20 weeks. Acid value, peroxide value, and TBA number of the samples under fluorescent light irradiation and $40^{\circ}C$ incubation increased slightly during storage, while a sharp increase of those values were noticed with the samples of ultra-violet light irradiation. Especially, the TBA number of the Ramyon lipid under ultra-violet light irradiation markedly increased within 10 weeks and then decreased. With this change in TBA number, however, the bound form of malonaldehyde increased gradually. During the storage under $40^{\circ}C$ incubation, and ultra·violet irradiation for 10 weeks, the content of linoleic and linolenic acids decreased, while palmitic and stearic acids increased. However, only small changes were noticed in iodine value of the samples. On the other hand, oxidative rancid odor appeared at the end of 16 weeks storage under fluorescent light irradiation and $40^{\circ}C$ incubation, while it took only 4 weeks with the sample stored under ultra-violet irradiation.

• Korean Journal of Medicinal Crop Science
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• v.5 no.2
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• pp.131-138
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• 1997

Campanulaceae having the most growing areas among medicinal crops cultivated in Korea occasionally failed to establish a reasonable standing in practice. The experiment was carried out to examine the effect of prechilling (0 : 4 : 8 days), light quality (red : white : dark) and daily irradiation hours (8 : 12 : 16) after sowing on seed germination and radicle elongation of Campanulaceae (Platycodon grandiflorum : Codonopsis lanceolata : C. pjlosula) to give an information on their earlier standing establishment. Mean germination rate of P. grandiflorum was the highest but that of C. pilosula was the lowest regardless of all the treatments. 12 hours irradiation or prechilling increased to 8 days enhanced their earlier or later germination, respectively. White light increased the rate of P. grandiflorum but alleviated that of C. lanceolata regardless of the daily irradiation hours. Although prechilling eliminated such effect of white light, light quality treatment effect on their mean germination rates was influenced by period after sowing, daily irradiation hours or prechilling. On the 9th day after sowing, C. lanceolata showed the greatest radicle length, and both daily 8 hours irradiation and 8 days prechilling enforced to elongate their radicles, while P. grandjflorum and C. lanceolata more lengthened their radicles in all prechilling treatments than in no chilling but C. pilosula showed the similar result only in the 8 days prechilling.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.368-382
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• 1998

The purpose of this study is to evaluate and compare the results of argon laser for 5 seconds, argon laser for 10 seconds, and visible light for 40 seconds photo-polymerization in compressive strength, microhardness, curing depth, temperature rising during polymerization, and polymerization shrinkage. Hybrid type composite resin(Z-100) and compomer(Dyract) were used to be compared. The compressive strength was measured by an Instron(1mm/min cross head speed) in 60 specimens and the microhardness of the surface was expressed by Vickers Hardness Number(VHN) in 30 specimens. The curing depth was evaluated comparing the different values of upper and lower VHN according to irradiation time and thickness for the light source polymerization in 60 specimens. The temperature rising during photopolymerization was observed by the temperature change with thermocouple sensitizer beneath 40 specimens at the argon laser for 10 seconds and visible light 40 seconds irradiation. The polymerization shinkage was evaluated by calculating the decrease of % volume by using a dilatometer in 30 specimens. The results were as follows ; 1. In the case of compressive strength, the argon laser polymerization groups were higher than visible light group in Z-100 (p<0.05). In Dyract, the argon laser 5 seconds group did not show a significant difference with the visible light 40 seconds group. The argon laser 10 seconds group showed the markedly low value when compared with other groups (p<0.05) 2. In microhardness, Z-100 was better than Dyract when comparing by VHNs (p<0.05); however, there was not a significant difference between two materials in the visible light 40 seconds group and the argon laser 10 seconds group. 3. In the study of curing depth, Z-100 showed the consistent polymerization in argon laser irradiation because there was no difference in the VHN decrease according to the thickness change. Over the thickness control, the results did not show a significant difference between visible light and argon laser group in Z-100; however, in the case of Dyract, the visible light 40 seconds group was better than the argon laser groups(p<0.05). 4. There was a significant difference between the two materials in temperature rising during polymerization (p<0.05), but not a significant difference between irradiation times, 5. There was not a significant difference between the two materials in polymerization shrink age. The argon laser 5 seconds group was smaller than the other groups (p<0.05). It could be concluded that Z-100 polymerization was recommended to use the argon laser for reduction of the irradiation time while Dyract was recommended to use the visible light polymerization.

• Korean Journal of Optics and Photonics
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• v.31 no.4
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• pp.183-190
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• 2020

In this paper, the illuminating optics of asymmetric light distribution was studied, which allowed the light distribution to be uniform even for short-range irradiation on a wide illumination area. In the case of a light installed at a short distance, the light is not diffused enough because of the short irradiation distance. For this reason, it is difficult to satisfy uniformity of illumination. In addition, lighting design for asymmetric distribution is required because the lighting device is installed tilted, for visibility. Therefore, the design of lighting systems with asymmetric light distribution could achieve uniform illumination of the target surface even under short-distance irradiation. This was then applied to the license lamp, a lighting system featuring short light irradiation distance, to confirm that it satisfies the legal standards.

• Current Optics and Photonics
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• v.6 no.3
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• pp.227-235
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• 2022

To investigate the aging-related physiological functions of organic light-emitting diodes (OLEDs), we examined mRNA expression changes in aging-related genes due to oxidative stress inhibition by 630-nm red light OLEDs. As a result of irradiating 630-nm OLED with an intensity of 5 mW/cm² for 15 min, the viability of dermal fibroblasts significantly increased by 1.3-fold. In addition, reactive oxygen species generated by H₂O₂ were significantly reduced about 4.9-fold by irradiation with 630-nm OLED. Quantitative reverse-transcription polymerase chain reaction results showed that 630-nm OLEDs altered aging-related gene mRNA expression levels through antioxidant activity. The mRNA expression levels of matrix metalloproteinase1 (MMP1) and MMP9 decreased significantly, by about 2.2- and 2.5-fold, compared to the control group, whereas those of collagen, type I, and alpha 1 increased significantly, by 4.9-fold. The mRNA expression levels of cancer suppression genes p16 and p53 in dermal fibroblasts were also significantly reduced by 630-nm OLED irradiation, by about 1.4- and three-fold, respectively, compared to the control. Overall, it was confirmed that 630-nm OLED irradiation lowered the level of ROS formation induced by H₂O₂ in dermal fibroblasts, and that this antioxidant effect could regulate the mRNA expression levels of aging- and tumor suppression-related genes. This study shows a link between 630-nm OLED irradiation and anti-aging physiological functions such as antioxidant function, and suggests the potential of OLEDs as a useful light source for skin care.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.417-425
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• 2023

Because an irradiation of 405 nm violet light could have a strong energy, it was used to be sterilized against various microbes in the indoor air condition or fresh food. Escherichia coli is a representative bio-pollutant in the indoor air-borne bacteria, and a hygienic microbe in the horticultural food. This study evaluated the inactivation influences on E. coli DS5α after exposure to 405 nm violet-light (VL) by investigating irradiating time, and the vertical and horizonal distance from light source. The illumination of 405 nm VL was inversely proportional to the distance from the VL source. E. coli DS5α on nutrient agar (NA) was inactivated approximately 50% more than the control when irradiated at 65 cm from 405 nm VL for 3 hours. When compared to the control, E. coli DS5α was inactivated approximately 50% within 70 cm from 405 nm VL for 3 hours. As it was irradiated for 3 hours 70 cm away from 405 nm VL, the horizonal distance from the point was negatively correlated to the inactivation of E. coli DS5α. These results indicated that the inactivation of E. coli DS5α grown on NA medium needs to be irradiated with 405 nm within 70 cm from the light source for 3 hours.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.220-223
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• 2002

This study investigated a lab-scale inducing method for efficient astaxanthin accumulation. As a model system. Haematococcus pluvialis was cultivated in 2 liter bubble-column photobioreactors. The astaxanthin - inducing results using high light irradiation were compared with that of the control experiment under standard irradiation (40 ${\mu}E/m^2/s$). After the late linear growth phase (> 20 days). high light energy (230 ${\mu}E/m^2/s$) was supplied to the culture broth for astaxanthin induction. As a result. the dr γ cell weight and the astaxanthin productivity were increased up to 68% and 215%, respectively. higher than those of the control experiment. This result indicates that bubble-column type photobioreactor is a good candidate for mass cultivation of H. pluvialis and high light irradiation is an efficient induction method for astaxanthin accumulation in lab-scale bubble-column photobioreactors.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.179-183
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• 2002

Lycopene as a natural antioxidant may provide protection against a broad range of epithelial cancers and chronic diseases. Lycopene concentrate extracted from tomatoes can be used as functional food. Lycopene would undergo degradation via isomerization and oxidation under different processing conditions, which impact its bioactivity and reduce the fuuctionality for health benefits. Heat and light induce lycopene oxidation and isomerization of all-trans form to cis form. The effects of thermal treatment and light irradiation on the stability of lycopene were determined. Results have shown that lycopene stability depends on the extent of oxidation and isomerization. Cir-isomers are less stable than trans-isomers. The level of cis-isomers increased as treatment time increased but only for a short period during the beginning of the treatment. The major effect of thermal treatment and light irradiation was a significant decrease in the total lycopene content. A true assessment of health benefits of lycopene concentrate depends on the lycopene content and the composition of all trans-isomers and cia-isomers.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1882-1884
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• 1999

The photoisomerization of functional polyimide was investigated in the various temperatures and UV(360nm) & visible(450nm) light irradiation. The absorption spectrum of azobenzene containing polyamic acid in a mixture of N,N-dimethylacetamide and benzene(1:1 by volume) solution was induced photoisomerization by UV and visible light irradiation. The absorption spectrum of LB films are also induced photoisomerization by UV and visible light irradiation.