• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.437-440
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• 2004

The radiation-induced changes taking place in poly(vinylidene fluoride)(PVDF) exposed to $^{60}Co\;\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co\;\gamma-ray$ to doses in the range of 200 to 1000 kGy. Various properties of the irradiated PVDF were studied using nm, differential scanning calorimetry(DSC) and gel fraction. $^{60}Co\;\gamma-ray$ irradiation was found to induce changes in chemical, thermal, structural properties of PVDF and such changes vary depending on the radiation dose.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.64-70
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• 2003

The thermal properties of chloroprene rubber (CR) with $^{60}Co\;{\gamma}$-ray irradiation has been investigated. The prepared CR was irradiated up to 1000kGy radiation dose by $^{60}Co\;{\gamma}$-ray and the radiation degradation of CR was investigated by thermogravimetric analysis and differential acanning calorimetry. Dynamic mechanical properties measurement and FT-IR observation are carried out as well. From these analyses results, the glass transition temperature($T_g$), decomposition onset temperature(DOT), oxidative induction time(OIT), the peak temperature of loss modulus and mechanical tan ${\delta}$ values were compared for the radiation degradation level of CR. The tendency between $T_g$ and peak temperature of loss modulus and mechanical tan ${\delta}$ agreed well with radiation doses. Decomposition temperature, OIT and DOT showed the same tendencies as increasing radiation doses. It was verified that these analyses are available to estimate the degradation level of CR.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.26-31
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• 2004

The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) exposed to $^{60}Co$ $\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co$ $\gamma-ray$ to doses in the range of 200 to 1000kGy. Various properties of the irradiated PVDF were studied using FTIR, differential scanning calorimetry (DSC), gel fraction and elongation. $^{60}Co\gamma-ray$ irradiation was found to induce changes in chemical, thermal, mechanical and structural properties of PVDF and such changes vary depending on the radiation dose.

• The Journal of Korean Society for Radiation Therapy
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• v.4 no.1
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• pp.12-16
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• 1990

• Journal of Sensor Science and Technology
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• v.9 no.5
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• pp.350-356
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• 2000

The optimum composition ratios of primary solute(p-terphenyl) and secondary solute(popop) have been investigated in order to fabricate plastic scintillator with higher light output and less radiation damage. The radiation damage induced by $^{60}Co$ $\gamma$-irradiation depends on mainly the concentration of secondary solute. The spectral range of the luminescence was $400{\sim}450\;nm$, its peak emission appeared at 415 nm. The transmittance and the light output were not changed by radiation damage up to $1{\times}10^4\;Gy$ irradiation with $^{60}Co$ $\gamma$-rays.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.205-209
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• 2012

The decomposition of 50 pesticides present in an aqueous solution using ${\gamma}-irradiation$ from a $^{60}Co$ gamma-ray source was investigated using laboratory-scale experiment. The rates of decomposition were determined using a gas chromatography-electron capture detector (GC-ECD), high-performance liquid chromatography-photo diode array detector (HPLC-PDA), and HPLC-fluorescence detector (FLD). When the initial concentration of pesticides was 10 ppm, and the radiation dose was 2, 5, 10, 20, and 30 kGy, respectively, 14 pesticide samples showed high removal rates (>50%) at absorbed doses of more than 10 kGy. With the exception of procymidone, they were all completely removed at a 30 kGy irradiation dose. These results provide fundamental data on the reactivity between gamma-irradiation and pesticides in an aqueous solution. Further, an evaluation of the toxicity of radiolytic intermediate products is required.

• The Journal of the Korean Society for Microbiology
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• v.8 no.1
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• pp.37-42
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• 1973

For the preparation of non-infective vaccine against typhoid fever, the authors had carried out an investigation on the possibilities of using $^{60}Co\;{\gamma}$-ray irradiation for the inactivation of Salmonella typhi Ty 2. The following results were obtained. 1) Chicks shortly after hatching were higher susceptible than mice to intracerebral injection with S. typhi. 2) In safety test on experimental animal, $^{60}Co\;{\gamma}$-ray irradiated vaccines demonstrated no clinical symptom while the phenol treated vaccines revealed several cases of narcosis by intraperitoneal injection in chicks. 3) The rabbit antisera immunized with $^{60}Co\;{\gamma}$-ray irradiated and phenol treated vaccine revealed almost same agglutinin titers to each other. 4) In potency test in chicks, there was no significance in the protective capacity between $^{60}Co\;{\gamma}$-ray irradiated and phenol treated vaccines.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.123-125
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• 2002

Blue light of Cherenkov radiation generated by electrons in transparent substances such as water and acrylic resin is well known generally. If students can easily observe the blue light at school, they may be impressed by the fascinating radiation. Four years ago, management of the Co-60 unit for radiotherapy was transferred to Nagoya University School of Health Sciences from a related hospital. We have examined whether or not the Cherenkov radiation in water from secondary electrons generated by Co-60 gamma-rays can be safely observed by eyes and photographs. First, the Cherenkov radiation in the water tank was led to the corridor outside the irradiation room by a mirror, and observed directly without any effect of the radiation exposure. Second, photographs of the Cherenkov radiation were taken under the conditions consisted of several irradiation fields and pass lengths of gamma-rays in water.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1634-1641
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• 2021

Exposure to gamma-rays is hazardous for humans and other living beings because of their high penetration through the materials. For this reason, shielding materials (usually lead, copper and stainless steel) are used to protect against gamma rays. This study's objective was to prepare ceramic materials for gamma radiation shielding by using different natural bentonite clays. Gamma-ray attenuation performances of the prepared shielding materials at different thicknesses were investigated and evaluated for different gamma-ray energies from different standard point gamma radiation sources (²⁵¹Am, ⁵⁷Co, ¹³⁷Cs, ⁶⁰Co, and ⁸⁸Y). The mass and linear attenuation coefficients of the prepared ceramics vary between 0.238 and 0.443 cm² g^-1 and between 0.479 and 1.06 cm^-1, respectively, depending on their thicknesses. Results showed that these materials could be prioritized because of their evidential properties of gamma radiation protection in radiation applications.

• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.216-222
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• 2002

In order to evaluate the antifungal activity of bacteria against plant pathogenic fungi, 8 bacteria were isolated from mushroom compost hot spring, seaweed, and forest soil and mutants from them were induced by $LD_{95}$ gamma radiation($^{60}Co$). Bacillus circulans K1, Burkholderia gladioli K4 and Bacillus subtilis YS1 showed wide antifungal spectrum against 12 kinds of plant pathogenic fungi. From the radiation sensitivity test, B. gladioli K4 was very sensitive to gamma radiation and its $D_{10}$ value was 0.11 kGy. Antifungal activities of B. circulans Kl-1004 and B. subtilis YS1-1009, which were induced by the radiation of $^{60}Co$ increased against Botryosphaeria dothidea. The mutant strains, B. subtilis YS1-1006 and B. subtilis YS1-1009 were resistant to tebuconazole and copper hydroxide. SAR535, SAR5108, and SAR5118 mutated from Streptomyces sp. SAR01 were antifungal activity deficient mutants against 5 kinds of plant pathogenic fungi compared to wild strain, so that they could be supposed to be model strains far studying antifungal mechanism. It is suggested that various functional types of mutants could be induced by gamma radiation and applied usefully.