• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.219-226
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• 1997

Ultralow background gamma-ray measurement system was installed to measure and analyze gamma-rays emitted from environmental and swipe samples. The background reduction techniques applied on this system are the passive shielding to surround the HPGe detector, an active external anticosmic shield to shield cosmic-rays and the nitrogen gas supply to minimize the introduction of ubiquitous radon decay nuclei. The performance test result showed that the system background at energies between 50 keV and 2 MeV is reduced about $10^{-2}$ order and the MDA is so low as to be suitable for the environmental sample analysis. But it is appeared that the neutron produced by cosmic-ray increases the background at low energy region.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2287-2292
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• 2012

In this study, $Co^{60}$ gamma-ray induced loss on Ge-doped single mode (SM) fiber has been measured. Gamma-ray is irradiated for 4 hours at the dose rate of 0.5 kGy/hr, 2 kGy/hr, 8 kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur significantly. Furthermore, dose rate effect was observed, that dose rate using the same total dose increased higher, then optical fiber loss increased more. Also annealing effect was observed, that the loss after irradiation, increased higher, then the recovery rate of loss was increased. This results are foreseen to be base data in the future radiation-hardened optical fiber study.

• Polymer(Korea)
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• v.30 no.1
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• pp.10-13
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• 2006

The effects of antioxidants and thermal treatment on the radiation resistance of the gamma-ray irradiated polypropylene (PP) were studied. The PP was blended with various antioxidants and was fabricated into a sheet. The PP sheet was irradiated with gamma-ray to a dosage of 25kGy in the nitrogen atmosphere. The differences in both color and mechanical strength were investigated for the gamma-ray irradiated PP depending on the kind and the content of antioxidant. The residual amount of free radical and the variation of oxidation index were investigated for the gramma-ray irradiated PP with thermal treatment after irradiation. The PP having phosphite antioxidant showed little difference in color after gamma-ray irradiation compared with the PP having phenolic or mine antioxidant. Sufficient amount of free radical could be removed from the gamma-ray irradiated PP by the thermal treatment at $130\;^{\circ}C$ for 30 min. Thermally treated PP showed lower oxidation index than the PP without thermal treatment.

• Korean Journal of Food Science and Technology
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• v.36 no.6
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• pp.900-904
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• 2004

Effects of gamma irradiation on brown rice quality were evaluated. Brown rice was irradiated at absorbed dose of 1, 3 or 5 kGy, and ground. Water uptake, pasting properties, and physicochemical characteristics of flour samples were tested. Water uptake rates of irradiated samples were higher than that of control, and were dose-dependent. Hydration capacity decreased in sample irradiated at 5 kGy due to leaching out of soluble compounds, whereas no differences were observed among other irradiated samples and control. Irradiation significantly decreased pasting properties as determined by amylograph. Gamma irradiation accelerated water evaporation at high temperatures (over $300^{\circ}C$) in test of weight-loss profile with thermogravimetric analyzer.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.107-112
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• 1987

Comparative effects of ethylene oxide and gamma radiation treatment of the microbiological and physicochemical qualities of ground garlic and onions were investigated. The standard ethylene oxide cycle employed was substantially less effective in reducing microbial counts than were 7 and 10 kGy of gamma radiation, and was roughly comparable to 5 kGy. Effects of gamma radiation on pungency, nutrient and color were relativey small in comparison with ethylene oxide which adversely affected physicochemical properties. Sensory evaluation indicated that no significant difference was observed between the nontreated control group and 10 kGy irradiated smaples.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.825-829
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• 2003

An electronic nose was applied to analyze the aroma patterns of powdered red ginseng that had been treated with different preservative methods, such as gamma radiation at 5kGy, commercial methyl bromide (MeBr) and phosphine fumigations. Aroma patterns of phosphine or MeBr, fumigated samples were well separated according to storage temperature and period. However, 5kGy-irradiated samples (stored for 1 and 2 months) were hardly discriminated by the different storage temperatures ($25^{\circ}C$ and $-10^{\circ}C$). After 5 months at $-10^{\circ}C$, non-treated and phosphine fumigated samples showed similar aroma patterns.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.764-770
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• 1997

For the purpose of improving hygienic quality of dried-spirullina and dried-sea tangle powders as raw materials of health food, the comparative effects of ozone treatment and gamma irradiation on the microbial and physicochemical properties were investigated. Gamma irradiation at 7.5 kGy resulted in sterilization of total aerobic bacteria, coliforms and molds below detective levels $(<10^{1}\;CFU/g\;sample)$, while ozone treatment for 8 hr up to 18 ppm could not sufficiently eliminate the microorganisms of the samples. Physicochemical properties including compositions of fatty acid and amino acid, minerals, pH and natural pigments were not changed by gamma irradaition up to 10 kGy, whereas, ozone treatment caused changes in pH, TBA value, natural pigments and fatty acid compositions. Especially, ozone treatment markedly decreased unsaturated fatty acid of the samples.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.6
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• pp.1035-1041
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• 2000

Gamma irradiation was used to improve sanitation and quality of salted and fermented anchovy sauce. For commercial production, comparison with currently using sterilization methods, such as micro-filtration and heat treatment were also conducted. Control was prepared without irradiation and sterilization process. Microbiological, physiochemical, and sensory qualities were analyzed to observe the Quality changes during the storage. Irradiation at 5 kGy or above and micro-filtration process completely eliminated microorganisms detected in this study As irradiation dose increased, the color appeared brighter and irradiation at 5 kGy or above showed similar color L-value to that of sample treated with microfiltration. The color L, a, b-value of heat-treated sample always showed lower. The pH, salinity, and viscosity were sustained during storage. From the results of sensory evaluation, the samples treated with gamma irradiation and microfiltration obtained better scores than control or heat-sterilized. Gamma irradiation to salted and fermented anchovy sauce presented the best quality products among different sterilizing methods, especially at 5 kGy dose. Therefore, gamma irradiation can be successfully applied to commercial large scale production as a new sanitation technology with improved quality.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.527-532
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• 1997

The comparative effects of gamma irradiation and ozone treatment on the microbial inactivation and fatty acid composition were investigated for improving hygienic quality of aloe and pollen powders. Gamma irradiation at 10 kGy resulted in sterilizing total aerobic bacteria, molds and coliforms below detective levels, while ozone treatment for 8 hours up to 18 ppm did not sufficiently eliminate the microorganisms of aloe and pollen powders. The compositions of fatty acid were not significantly changed by gamma irradiation up to 10 kGy. However, ozone treatment markedly decreased unsaturated fatty acids by approximately $20{\sim}80%$ in contents, whereas it significantly increased saturated fatty acids (p<0.05).

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.355-360
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• 2002

Effect of additive on color reversion of green tea extract, whose undesirable color had been removed by irradiation, was studied during storage. Hunter color L-vague of irradiated sample was significantly higher than that of nonirradiated control. The color of green tea extract with butylated hydroxyanisole (BHA) did not differ from that of the control but the green tea extract with ascorbic acid had higher L-value than the control during the whole storage (p<0.05), However, the sample irradiated at 20 kGy showed a faster color reversion than the sample with 5 or 10 kGy of irradiation. Hunter color a-values were decreased by irradiation and the sample with ascorbic acid showed the lowest. The result of Hunter color b-value was also similar to that of Hunter color a-value, indicating that when the irradiation technology is used for color improvement of green tea extract, the ascorbic acid can be added to minimize color reversion of the extract during delivery or storage.