• Journal of Radiation Industry
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• v.7 no.1
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• pp.51-54
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• 2013

Chitosan is a useful natural polymer material in many application fields such as biomaterials, water-treatment, agriculture, medication, and food science. However, the poor solubility limits its application. In this study, the effects of radiation on chitosan were investigated using gamma ray and electron beam irradiation. The chemical structure and molecular weight analysis show similar degradation effects of chitosan powder in both gamma ray and electron beam irradiation. However, the radiation irradiated chitosan in $H_2O$ has a lower molecular weight, since the hydroxyl radicals attack the glycosidic bonds. This effect is more clearly shown in the electron beam irradiation results.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.271-272
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• 2010

Sensitivity analysis by TSUNAMI clarifies the complex effects of key nuclides on the criticality probability quantitatively. As discussed above, the $K_{eff}$ of $UO_2$ fuel reaches the maximum value with 42w% concentration of intrusion water. The concentration of hydrogen affects the complexity of reaching criticality by its competition between the concentrations of $^{235}U$. Approximately if the weight percent of $H_2O$ in the mixture is less than 42%, the moderation effect of hydrogen surpasses its dilution effect on $^{235}U$. However, the importance of $^{235}U$ increases dramatically when the weight percent of water is bigger than 42%. In the sensitivity evaluation of $UO_2$ fuel employing TSUMAMI, there is a similar crosspoint of the sensitivity of $^{235}U$ and the sensitivity of $^1H$ where the criticality reaches summit. And the optimal water weight percent is determined to be 50%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2167-2173
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• 1996

An approximate weight function technique using the indirect boundary integral equation has been presented for the analysis of stress intensity foactors(SIFs) of a thick pipe. One-term boundary integral was introduced to represent the crack surface displacement field for the displacement based weight function technique. An explicit closed-form SIF solution applicable to symmetric cracked pipes without any modification of the solution including both circumferential and radial cracks has been derived. The necessary information in the analysis is two or three reference SIFs. In most cases the SIF solution were in good agreement with those available in the literature.

• Preventive Nutrition and Food Science
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• v.16 no.1
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• pp.83-88
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• 2011

The wholesomeness of 40 kGy irradiated ready-to-eat (RTE) bulgogi was evaluated by subacute toxicity studies (body weight, food consumption, organ weight, hematology, serum biochemistry, and histopathological examination) with groups of 40 male and female ICR mice fed the agent at dietary levels of 5% for 90 days. There were no treatment-related adverse effects with regard to body weight, food consumption, organ weight, hematology, serum biochemistry, and histopathology. The no-observed-adverse-effect-level (NOAEL) was also determined to be greater than dietary level of at least 5% (3900 mg/kg body weight/day for males, 3500 mg/kg body weight/ day for females) for samples under the present experimental conditions. These results suggest that, under these experimental conditions, RTE bulgogi irradiated at 40 kGy did not show any toxic effects.

• Korean Journal of Environmental Biology
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• v.21 no.4
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• pp.400-404
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• 2003

This study was to evaluate the effects of gamma irradiation on the germination, nutrient concentrations and growth of spinach and radish. Both the spinach and radish seeds exhibited relatively higher germination rates in response to the low doses of gamma irradiation compared to the non -irradiated control. Leaf DW of the radish did not respond to gamma irradiation but that of the spinach increased significantly in response to a gamma radiation of 4 Gy (P< 0.05). Leaf growth parameters of the spinach including the leaf area and SLA (leaf area/leaf dry weight) also demonstrated increased responses to gamma irradiation. R/S (root dry weight/shoot dry weight), root DW and root length of the spinach exhibited a positive response to gamma irradiation while those of the radish did not. In contrast, SRL (root length/root dry weight) significantly decreased with gamma irradiation at 8 Gy for the spinach, but not for the radish. The tissue nitrogen concentrations of the spinach showed an increased response to gamma irradiation while that of the radish did not. Furthermore, higher concentrations of phosphorus, potassium, calcium and magnesium were found in the irradiated spinach, but not in the irradiated radish. It seems that the non-specific physiological and/or biochemical activities of spinach might be accelerated by gamma irradiation, possibly accounting for the stimulation of nutrient uptake from the root media and early biomass accumulation in the current study.

• Korean Journal of Pharmacognosy
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• v.46 no.4
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• pp.283-288
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• 2015

In this study, we investigated anti-obesity effect of isoegomaketone (IK) isolated from leaves extract of Perilla frutescens (L.) Britt. cv. We verified differentiation and lipid accumulation by Oil Red O staining in 3T3-L1 cells after IK treatment with differentiation media. IK inhibited mRNA expression of adipocyte specific genes that were related with differentiation of 3T3-L1 cells. We confirmed the effects of IK on body weight and visceral fat mass in obese mice. Mice were randomly divided into three groups; normal diet group (ND), high-fat diet group (HFD) and high-fat diet with IK group (HFD-IK). The obesity mice were induced by feeding the 45% high-fat diet to the C57BL/6J mice during 4 weeks. After HFD-IK was orally administered 10 mg/kg of IK. As a result, the body weight of HFD and HFD-IK was increased 2.4 times and 1.7 times of ND, respectively. Also visceral fat mass of HFD was increased 24 times but in the case of HFD-IK was increased to 13 times in comparison with ND. Taken together, our findings suggest that IK reduced differentiation and adiogenesis in 3T3-L1 cells, decreased the body weight and visceral fat mass in obesity mice. These results suggest that IK may have a potential benefit as anti-obesity material.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.167-168
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• 2017

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.449-458
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• 2007

In this paper, we reconstructed the cross-sectional images of two phantoms simulating a petrochemical process from gamma radiation measurements. Three different weight functions for EM image reconstruction algorithm were built and compared with histograms representing the variance of the homogeneity of the phantom material, The radiation source, $^{137}Cs$, collimated by a lead with 5 mm diameter aperture and the measurement was made with a lead shielded 1inch NaI detector. As a result, the method taking into account the beam area in each pixel for a weight function showed the best resolution among the three methods.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.61-65
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• 2012

Polyacrylonitrile (PAN) is one of the most widely used precursor polymers for making high performance carbon fibers. Conversion of PAN fibers to good quality carbon fibers requires an essential stabilization step prior to carbonization. Electron beam irradiation is an excellent technique for modifying the physical properties of materials. This study aimed to elucidate the effects of electron beam irradiation on the stabilization reactions of PAN nanofibers. FT-IR analysis indicated that the stabilization of irradiated PAN nanofibers was initiated at a lower temperature. The TG curve of PAN nanofibers showed a significant decrease of weight loss step between 280 and $320^{\circ}C$. In the case of irradiated PAN nanofibers, weight loss sudden weight did not loss occurs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.773-774
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• 2016

In this study, we perform the weight reduction and miniaturization of the shielding element that is applied for gamma-ray detectors for imaging of gamma-ray source. Through previous studies, we implemented a lead-based shielding element that represents the shielding effectiveness and performance of commercially available gamma-ray imaging apparatus similar to the shielding body. In this paper, we designed a tungsten-based shield for weight reduction and miniaturization than lead-based shield. We performed the MCNP simulation for shield design and then we obtained the results of reducing the weight of the 17% and 51% of the volume.