• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.343-348
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• 2003

To elucidate the effect of gamma-irradiation on the physicochemical properties of zein films, the molecular and mechanical properties of the films were examined after irradiation at various irradiation doses. Gamma-irradiation of zein solutions caused the disruption of the ordered structure of the zein molecules, as well as degradation, cross-linking, and aggregation of the polypeptide chains based on an SDS-PAGE study. Gamma-irradiation increased the solubility of zein and decreased the viscosity due to cleavage of the polypeptide chains. Protein solubility of the zein films in urea/2-mercaptoethanol also increased with increasing irradiation doses. Alterations of the zein molecules by irradiation decreased water vapor per-meability by 12% and increased the elongation of zein films. However, mean tensile strength of the zein films was decreased by gamma-irradiation treatment. Measurement of Hunter color values indicated that irradiation caused a destructive effect on yellow pigments, resulting in a significant decrease in Hunter b values. The microstructure as observed by scanning electron microscopy showed that irradiated zein film had a smoother and glossier surface than the non-irradiated films.

• Journal of the Korean Solar Energy Society
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• v.38 no.3
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• pp.1-20
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• 2018

It is a very important and fundamental process to know accurately the intensity of the solar energy coming into the installed module considering the tilted angle. Europe and the US commonly use a program called PVsyst to convert the global horizontal irradiation to global irradiation on tilted plane. There are two types of models that PVsyst uses to convert to irradiation on tilted plane. In this paper, Perez model, which is a decomposition model and Perez model, which is a transposition model used in PVsyst, are applied based on global horizontal irradiation and global irradiation on tilted plane measured in a specific area. The comparison of the decomposition model shows the effect of the transpostion model on global irradiation on tilted plane conversion by comparing the ratio of the horizontal diffuse irradiation amount of the Watanabe model which are highly trusted in Asia and the Perez model. The comparison of transposition model confirm the error between the measured data and the calculated value which is applied Perez model to global horizontal irradiation decomposed by Perez model and Watanabe model. Based on the two comparisons, This paper propose a method to confirm the reliability of transposition model and reduce the error when PVsyst is used in Korea.

• Imaging Science in Dentistry
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• v.35 no.3
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• pp.147-156
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• 2005

Purpose : To observe the histopathological changes and caspase-3 expression in the submandibular gland in streptozotocin-induced diabetic rats after irradiation. Materials and Methods : The male Sprague-Dawley rats weighing approximately 250 gm were divided into four groups: control, diabetes, irradiation, and diabetes-irradiation groups. Diabetes mellitus was induced in the rats by injecting streptozotocin. Rats in the control and irradiation groups were injected with citrate buffer only. After 5days, rats in irradiation and diabetes-irradiation groups were irradiated with a single absorbed dose of 10 Gy to the head and neck region. All the rats were sacrificed at 3, 7, 14, 21, and 28 days after irradiation. The specimen including the submandibular gland were sectioned and observed using histopathological and immunohistochemical methods. Results : In the irradiation group, the condensed nucleus, karyolysis, and degeneration of the acinar cells and atrophy of the duct cells were observed in the early experimental phase. However, the acinar cells were found to be normal at 28 days after irradiation. In the diabetes group, the condensed nucleus, karyolysis, atrophy, and degeneration of the acinar cells were observed in the early experimental phase. However, the acinar cells were found to be normal at 21 days after diabetic state induction. In the diabetes-irradiation group, the ductal epithelial cells were predominant in their glandular tissues at 28 days after irradiation. In all of the experimental groups, the most prominent change of the acinar cells and ductal cells were observed at 14 days after diabetic state induction and irradiation. Conclusion The expression of caspase-3 in the acinar cells and ductal cells of the submandibular gland was weak after irradiation, but that in the acinar cells, ductal cells, and fibrous cells of the submandibular gland was prominent after diabetic state induction.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.30-34
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• 1999

Photolysis behavoirs of pesticides(Chlorothalonil and Endosulfan) over UV irradiation UV irradiation with pH 3.0 and irradiation with 3.5% salt were studied. The analyses of pesticides were carried out using gas chromatograph with an electron-capture detector, total organic carbon, and Ion chromatograph, respectively. The reactions were conducted in a alumium annular reactor equipped with a low pressure mercury multilamp ($8W{\times}6$) and initial concentration was 10 ppm. Chlorothalonil was almost photodegraded by UV irradiation, UV irradiation with pH 3.0 and 3.5% salt within 30 min of reaction time. Endosulfan-${\alpha}$,${\beta}$(100%) were photodegraded to 38% of Endosulfan-${\alpha}$ and 25% of Endisulfan-${\beta}$ by UV irradiation. Endosulfan-${\alpha}$(83%) was photodegraded to 66% by UV irradiation, 70% by UV irradiation and pH 3.0 and 75% by UV irradiation and 3.5% salt. Endosulfan-${\beta}$(16%) was photodegraded to 80% by UV irradiation, 98% by UV irradiation and pH 3.0 and 90% by UV irradiation and 3.5% salt.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.19 no.1
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• pp.39-48
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• 1989

Six to eight-month-old female albino rats were used as experimental animals. As an irradiation equipment, a Co-60 was used. The experimental animals were divided to; 6 of the control group, 12 of the 500cGy single irradiation group, 12 of the 1000cGy fractionated irradiation group, and 12 of the 1500cGy fractionated irradiation group. From the first week to the forth, 3 rats were picked from each group every week to be sacrificed and fixed with formalin. Those rats were observed by means of H-E stain after being taken radiograph and decalcified. The analysis of radiographic findings and light microscopic findings gives results as follows: 1. The delay of dental eruption rate was found in every group which underwent the irradiation experiment. Dentin niche, osteodentin, and dentin island were formed in the parts which were damaged by the irradiation. 2. The longer the observation period was, the more deposit of osteodentin and dentin island was formed. 3. In the single irradiation group, the damage effect was in proportion to the increase of radiation dose, whereas the damage was much less in the fractionated group receiving the same dose. 4. The 500cGy single irradiation group got temporary repairable damage, while the 1000cGy single irradiation group got considerable damage and showed much slower eruption rate than the 500cGy single irradiation group. The basal portion of the 1500cGy single irradiation group, whose growth was arrested, was destroyed. 5. The fractionated group were irradiated 500cGy everyweek. Repair was visible during the interval periods. The damage was accumulated as irradiation repeated, but degree of damage was lower than that of the 1000cGy and 1500cGy single irradiation group.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.1
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• pp.23-27
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• 2005

We observed that optical properties of silicon changed under high dose electron irradiation at 250 keV. Our experimental results revealed that the optical transmission through a silicon wafer is significantly increased by electron irradiation. Transmission increase by the change in the absorption coefficient is explained through an analogy with amorphous silicon. Moreover, solar cell open-circuit voltages indicated that defects were generated by electron irradiation, and that the defects responded to annealing. Our results demonstrated that the optical properties of silicon can be controlled by a combination of electron irradiation and hydrogen annealing.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.183-197
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• 1991

After single fraction of 2, 5, 10 Gy irradiation on submandibular gland of 40 male rats, weighing 150gm, respectively, these animal were sacrificed two hours after 0.1㎎/g bromodeoxyuridine (Sigma) peritoneal injection in 1, 3, 7, 15 hours, 1, 3, 7 days after irradiation. And excised submandibular gland were fixed in Carnoy's and Bouin's solution for 2 hours. Paraffin sections were stained with H&E, and PAS for the observation of the change of salivary gland tissue, and with Feulgen for the study of the DNA distribution, and immunohistochemically stained with anti-bromodeoxyuridine (Sanbyo Co.) for detection of DNA synthetic cells in order to study the distribution of DNA synthetic cells of salivary gland tissue and endothelium after irradiation in 5 different sites of 6 slides on X 200 high power field. The results were as followings. 1. In PAS staining 3 days after 5Gy irradiation, decreased mucine secretion of serous cells were found, and 7 days after l0Gy irradiation, decreased mucine secretion of mucous cells were found. 2. In histopathologic features, degeneration of serous cells were found in 3 days after 2 Gy irradiation and there was little change in mucous cells and excretory duct cells. 3. In Feugen staining, 3 days after 2 Gy, 5 Gy irradiation, more high percentage of DNA synthetic cells were found in intercalated duct cells, striated duct cells and excretory duct cells than in BrdU staining. 4. In immunohistochemical features, DNA synethsis of serous cells and granular convoluted tubular cells abruptly decreased in early period after irradiation and showed no recovery in 7 days after irradiation but there was an increase in DNA synthesis of intercalated duct cells, striated duct cells and excretory duct cells, which have less S-phase cells comparatively, in 7 days after 2 Gy, 5 Gy irradiation. 5. In immunohistochemical features, the DNA synthesis of endothelial cells was continuously decreased after irradiation but showed slight increase in 7 days after 2 Gy and S Gy irradiation.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.33-40
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• 2006

Purpose : To investigate clusterin expression in the acini and ductal cells of rat submandibular glands after Co-60 gamma irradiation. Materials and Methods : The male Sprague-Dawley rats weighing approximately 250 gm were divided into control and experimental groups. The experimental group was irradiated with a single absorbed dose of 2, 5, 10, and 15 Gy on the head and neck region. All the rats were sacrificed at 1, 3, 7, 14, 21, and 28 days after irradiation. The specimens including the submandibular gland were sectioned and observed using a immunohistochemical method. Results : In the 2 Gy group, clusterin expression was similar to that of the control group at 1 day after irradiation and it was observed in the striated ductal cells at 3 days after irradiation. In the 5 Gy group, clusterin expression was observed in the striated ductal cells at 1 day after irradiation and gradually increased in the 10 and 15 Gy groups. In the 15 Gy group, clusterin expression was prominent in the striated ductal cells at 1 day after irradiation, but it gradually decreased with the experimental period. The destruction of the striated ductal cells was observed in the 2 Gy group at 21 days after irradiation and in the 5, 10, and 15 Gy groups at 7 days after irradiation. The destruction of the acinar cells was observed in the 2 Gy group at 28 days after irradiation and in the 5, 10, and 15 Gy groups at 14 days after irradiation. Conclusion : Clusterin expression was induced by low doses of irradiation and it appeared to be involved in the regulation of cellular response to irradiation.

• Journal of the Korean Society of Food Culture
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• v.15 no.4
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• pp.269-277
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• 2000

A survey was conducted to examine the knowledge and acceptance of food irradiation in order to provide baseline data required in the development of food irradiation education programs for college students. 150 students majoring in food and nutrition or food technology in the Chungnam National University were chosen for a survey. The results are as follows. First, college students' knowledge about food irradiation is scanty. Knowledge assessment showed that 56% of the participants had previously heard of food irradiation. 68% of the respondents thought that radioactivity remains in food after irradiation and 25.3% of them were not sure whether radioactivity remains in food after irradiation or not. Only half of the respondents thought that nutrient loss due to irradiation is equal to or lower than that due to cooking or freezing. Second, approximately 56% of the respondents showed that food irradiation is somewhat or strongly needed for meat or fish; whereas, over 60% of them showed that food irradiation is not needed for grain, vegetable and fruit. Almost 40% of the respondents were seriously concerned about irradiation of vegetables and fruits; whereas, they showed less concern about spice irradiation. More than half of the respondents were not willing to use irradiated food in all the six food groups. Third, the correlation analysis showed that the need of food irradiation is negatively correlated with concerning about the irradiated fish and fruits, but positively correlated with willingness to use irradiated food in all the five food groups, except in spices. Concern about the irradiated food is negatively correlated with willingness to use irradiated food from all the six food groups. Fourth, almost all the respondents (over 90%) agreed that the irradiated food labeling is required as well as the development of proper methods to identify irradiated foods.

• 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.