• 방사선산업학회지
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• 제12권4호
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• pp.349-353
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• 2018

Metronidazole (MD), which is used as an antibiotic, is largely used as an oral and skin application agent, and has inhibiting effect on the production of the fungus causing malodor. However, the maximum drug inclusion concentration is 0.75% of skin ointment in commercially available. In this study, hydrogels containing high concentration of metronidazole were prepared by using radiation crosslinking technique based on biocompatible polymers, and release characteristics and antimicrobial properties were evaluated. This study was preliminary carried out to investigate whether it could be used effectively as antibacterial dressing materials.

• 대한금속재료학회지
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• 제48권5호
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• pp.410-416
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• 2010

Studies were carried out to establish the technology for sodium-clad compatibility and to analyze the compatibility behavior of the Sodium-cooled Fast Reactor (SFR) cladding material under a flowing sodium environment. The natural circulation facility caused by the thermal convection of the liquid sodium was constructed and the 316-series stainless steels were exposed at $650{^{\circ}C}$ liquid sodium for 1458 hours. The weight change and related microstructural change were analyzed. The results showed that the quasi-dynamic facility represented by the natural convection exhibited similar results compared to the conventional dynamic facility. Selective leaching and local depletion of the chromium, re-distribution of the carbide, and the decarburization process took place in the 316-series stainless steel under a flowing sodium environment. This process decreased as the sodium flowed along the channel, which was caused by the change in the dissolved oxygen and carbon activity in the liquid sodium.

• 방사선산업학회지
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• 제6권2호
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• pp.111-117
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• 2012

This study was conducted to improve organoleptic quality of gamma-irradiated Tarakjuk at 10 kGy with cheeses (Camembert, Cheddar, Gouda, and Edam) and flavors (Nurungji, cream, and vanilla-cream). Overall acceptability of gamma-irradiated Tarakjuk added each camembert cheese and vanilla-cream flavor was the highest among the all samples. In the effect of sterilization method on the quality of Tarakjuk, the autoclaved samples added with Edam cheese, Gouda cheese, and vanilla-cream flavor, respectively, were showed higher score on the overall acceptability than the irradiated samples, meanwhile the irradiated samples were superior in the other samples. In case of added mixture of Edam cheese and vanilla-cream flavor, irradiated Tarakjuk with mixture was showed the most of high score on overall acceptability. In conclusion, addition of mixture of cheese and flavor to Tarakjuk may help to improve organoleptic quality of sterilized Tarakjuk by gammairradiation.

• 방사선산업학회지
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• 제8권2호
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• pp.123-132
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• 2014

After the nuclear accident of the Fukushima Dai-ichi Nuclear Power Plants (FDNPPs) on 11 March 2011, a large amount of radioactive materials has been released into the atmosphere and the ocean. A compartment model is used to evaluate the circulation characteristics and the spatiotemporal concentration distributions of radionuclides in the ocean. In the comparison with observed concentrations of $^{137}Cs$ in seawater, calculated concentrations by the compartment model were well agreed with them. On the basis of these results, we performed evaluation of the effective dose and the cancer risk. In the early stage of the accident, the effective doses from ingestion of the seafood near the Fukushima region were much higher than 1 mSv which is the value of the annual effective dose limit to individual recommended by the International Commission on Radiological Protection (ICRP). However, the effective doses by ingestion of the seafood decreased below 1 mSv as distance from the FDNPPs increased and time passed. In addition, it was estimated that the cancer risks by intake of the contaminated marine products were less than natural occurrence probability of cancer. Consequently, it was inferred that the health risk due to the $^{137}Cs$ was low after since mid-term period of the accident.

• 방사선산업학회지
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• 제6권2호
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• pp.177-180
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• 2012

The acid and bile tolerance changes of 5 different lactic acid bacteria (LAB; Lactobacillus paracasei, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus debruekii) with gamma irradiation were evaluated. The abilities of LAB to survive in the acidic conditions at the stomach and the bile acidic conditions at the beginning of the small intestine are the key functions for applying LAB to probiotics. In the results, all of LAB survived more than 50% after incubation in PBS (pH 2.5) for 2 hr, which indicated more than half of LAB are possible to pass through the stomach. However, gamma irradiation decreased the acid tolerances of LAB. The bile tolerances of all bacteria except Lactobacillus acidophilus were observed to survive at a 3% oxgall concentration in MRS, and 1 kGy of gamma irradiation to LAB did not affect any bile tolerances changes. But gamma irradiated Lactobacillus casei and Lactobacillus casei (3 kGy) showed decreasing survival rate with oxgall added MAS agar. In conclusion, gamma irradiation should be applied to yogurt or fermented foods with care because LAB could be changes their properties on acid and bile tolerances.

• 방사선산업학회지
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• 제6권1호
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• pp.23-29
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• 2012

In this study, we investigated the genetic variation in the general of monocot model plant (rice) in response to various ionizing irradiations including gamma-ray, ion beam and cosmic-ray. The non-irradiated and three irradiated (200 Gy of gamma-ray and 40 Gy of ion beam and cosmic-ray) plants were analyzed by AFLP technique using capillary electrophoresis with ABI3130xl genetic analyzer. The 29 primer combinations tested produced polymorphism results showing a total of 2,238 bands with fragments sizes ranged from 30 bp to 600 bp. The number of polymorphism generated by each primer combinations was varied significantly, ranging from 2 (M-CAC/E-ACG) to 158 (M-CAT/E-AGG) with an average of 77 bands. Polymorphic peaks were detected as 1,269 with an average of 44 per primer combinations. By UPGMA (Unweighted Pair Group Method using Arithmetic clustering) analysis method, the clusters were divided into non-irradiated sample and three irradiated samples at a similarity coefficient of 0.41 and three irradiation samples was subdivided into cosmic-ray and two irradiation samples (200 Gy of gamma-ray and 40 Gy of ion beam) at similarity coefficient of 0.48. Similarity coefficient values ranged from 0.41 to 0.55.

• 방사선산업학회지
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• 제9권1호
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• pp.9-13
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• 2015

Epoxy resin is widely used as aerospace, automobile, construction and electronics due to their good mechanical and electrical properties and environmental advantages. However, the inherent flammability of epoxy resin has limited its application in some field where good flame retardancy is required. Nano clay can enhance the properties of polymers such as flames retardancy and thermal stability. In this study, we have investigated the nanoclay filled epoxy composite, which has good flame retardancy while maintaining high mechanical properties. The cured epoxy resins were obtained using an electron beam curing process. The nano clays were dispersed in epoxy acrylate solution and mechanically stirred. The prepared mixtures were irradiated using an electron beam accelerator. The composites were characterized by gel content and thermal/mechanical properties. Moreover, the flammability of the composite was evaluated by limited oxygen index (LOI). The flame retardancy of nano clay filled epoxy composite was evidently improved.

• 방사선산업학회지
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• 제7권1호
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• pp.45-49
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• 2013

In tissue engineering application, a fibrous structure of scaffolds has been issued as an alternative system to regulate cell survival and tissue regeneration, and electrospinning technique has been popularly used to generate fibrous meshes or sheets mimicking the structure of native extracellular matrix (ECM). However, recent strategy in the scaffold development is expanded to provide the structural property as well as a biological property of native ECM, a variety of surface modification techniques have been used to introduce biological property. In this study, we developed biomimetic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nano- and micro-fibrous scaffolds as a unique platform with structural and biological properties with native ECM using electrospinning method and gamma-ray irradiation. Surface morphology of the scaffolds was observed by scanning electron microscopy, and alteration of surface property was evaluated with toluidine blue O staining, water contact angle measurement and ATR-FTIR analysis.

• 대한금속재료학회지
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• 제48권10호
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• pp.893-900
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• 2010

In the present work, the impact loads and their effects on the surface damage under the simultaneous cavitation bubble and solid particle collapses in the sea water have been quantitatively investigated for the austenitic 304 stainless steel by using a vibratory cavitation test device. To do this, angular $SiO_2$ solid particles with an average size of $150{\mu}m$ were dispersed into the test liquid, and the measured impact amplitudes were converted into the impact loads by a steel ball drop test. The maximum impact load was determined to be 28.2 N in the absence of solid particles, but increased to 33.7 N in the presence of solid particles. In addition, the critical impact loads, $L_{crit}$, required to generate pits with sizes greater than $3{\mu}m$ were measured to be 19.6 N and 16.6 N, respectively, for the cavitation bubble collapse and solid particle collapse. As a result of the cavitation erosion test, the incubation time and erosion rate were 1.2 times lower and 1.5 times higher, respectively, by a solid particle collapse compared to those only by the cavitation bubble collapse, indicating a drastic decrease in a resistance to cavitation erosion by the solid particle collapse.

• 방사선산업학회지
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• 제5권1호
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• pp.55-62
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• 2011

We investigated the physiological responses by acute and chronic gamma-irradiation in rice. The rice, Oryza sativa L. cv Dongan, plants were irradiated with 100 and 400 Gy of gamma-rays for acute and chronic irradiation, and their morphological, chlorophyll content, MDA, proline and activities of antioxidant enzymes were examined. The plant height of chronic irradiation samples were decrease with increase of a does than the control, but the number of tiller and dry weight of shoot were increased 100 Gy. Carotenoid and chrolorphyll content were decreased of all irradiated plants than non-irradiated plants. But, MDA and proline content were increased in 400 Gy both acute and chronic gamma irradiation. And the activities of antioxidant enzymes were different as gamma-irradiation patterns.