• Journal of computational fluids engineering
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• v.21 no.4
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• pp.33-39
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• 2016

Generally, thermal analysis of spent fuel storage cask has been conducted using the porous media and effective thermal conductivity model to simplify the structural complexity of spent fuel assemblies. As the fuel assembly is composed of two regions; active fuel region corresponding to UO2 pellets and unactive fuel region corresponding to the top and bottom nozzle, the heat transfer performance can be influenced depending on porous media application at these regions. In this study, numerical analysis on concrete storage cask of spent fuel was performed to investigate heat transfer effects for two cases; one was porous media application only to active fuel region(case 1) and the other one was porous media to whole length of fuel assembly(case 2). Using computational fluid dynamics code, the three dimensional, 1/4 symmetry model was constructed. For two cases, maximum temperatures for each component were evaluated below the allowable limits. For the case 1, maximum temperatures for fuel cladding, neutron absorber and baskets inside the canister were slightly higher than those for the case 2. In particular, even though the helium flows with low velocity due to buoyant forces occurred at the top and bottom of unactive fuel region, treating only active fuel region as the porous media was ineffective in respect of the heat removal performance of concrete storage cask, implying a conservative result.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.1
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• pp.45-63
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• 2017

The oldest commercial reactor in South Korea, Kori-1 Nuclear Power Plant (NPP), will be shut down in 2017. Proper treatment for decommissioning wastes is one of the key factors to decommission a plant successfully. Particularly important is the recycling of clearance level or very low level radioactively contaminated metallic wastes, which contributes to waste minimization and the reduction of disposal volume. The aim of this study is to introduce a conceptual design of a recycle system and to evaluate the doses incurred through defined work flows. The various architecture diagrams were organized to define operational procedures and tasks. Potential exposure scenarios were selected in accordance with the recycle system, and the doses were evaluated with the RESRAD-RECYCLE computer code. By using this tool, the important scenarios and radionuclides as well as impacts of radionuclide characteristics and partitioning factors are analyzed. Moreover, dose analysis can be used to provide information on the necessary decontamination, radiation protection process, and allowable concentration limits for exposure scenarios.

• The Korean Journal of Physiology
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• v.4 no.2
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• pp.61-67
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• 1970

In view of the importance of sulfhydryl groups in producing a chemical protection against ionizing radiation, an attempt was made to evaluate the changes of intrinsic non-protein sulfhydryl (NP-SH) and non-Protein disulfide(NP-SS) of the lung and liver tissues of rabbits following the whole body X-irradiation with 900 r either in single or fractionated $(300\;r{\times}3)$ dose. NP-SH was measured by Ellman's method, and NP-SS was measured by the electrolytic reduction method described by Dohan. Experiment was performed at 1,3,5,24 and 48 hours post·irradiation, and the results were compared with the control. The results thus obtained are summarized as follows; 1) Intrinsic levels of NP-SH and NP-SS of normal rabbits were $0.77{\pm}0.10$ and $0.61{\pm}0.07\;{\mu}mol/gm$ wet weight in liver, and $0.28{\pm}0.03$ and $0.54{\pm}0.03$ in lung tissues respectively. 2) NP-SH of liver after single X-irradiation showed no significant change in general, but at 48 hours post·irradiation, it was elevated comparing with the normal value. 3) Levels of NP-SS in liver was decreased than the normal value in the irradiated groups, and the lowest level was observed at 3 hours after single X-irradiation and at 5 hours after fractionated irradiation. 4) In lung tissues, levels of NP-SS showed no significant change from the control at earlier experimental hours, but a great decrease was observed at later Part of the experiment.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.445-448
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• 2004

Aging is divided into intrinsic aging and photo-aging. Intrinsic aging is naturally occurred as the time passed and photo-aging is induced by the UV radiation of skin. The main reason of aging is the free radicals and the degeneration of the cellular materials by free radicals. In this paper, we checked the anti-aging effects of Mallotus japonicus bark extracts. It has the ability to scavenge free radicals and the SOD like activity. Also, it reduced the cell damage by hydrogen peroxide treatment. Mallotus japonicus bark extracts showed the excellent activity on inhibiting the UV induced cell damage and DNA damage. In conclusion, Mallotus japonicus bark extracts can be used as active ingredients for anti-aging cosmetics.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.820-829
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• 2003

One of the important function of skin is the protection from harmful environments. Many studies were carried out to keep the skin from wrinkling and pigmenting. Skin wrinkle and pigmentation could be caused' by the unusual disruption of connective tissue, the formation of free radicals and the radiation of ultraviolet. In this study, the extracts obtained from 23 different kinds of medicinal plants were examined whether they have inhibitory effect on tyrosinase and elastase as well as free radical scavenging effect. All the extracts examined were obtained by using 70% (v/v) ethanol at $60^{\circ}C$. It has been found that there were two medicinal plants which have positive effects matching with the purpose of this study. The extract of Ephedra sinica stapf shows an inhibitory effect on tyrosinase ($IC_{50}$ = 83.7~$\mu\textrm{g}$/ml), on elastase ($IC_{50}$ = $690{\mu}\textrm{g}$/ml), and also shows free radical scavenging effect ($IC_{50}$ = 29.6$\mu\textrm{g}$/ml). The extract of Betula platyphylla Var. shows an inhibitory effect on elastase ($IC_{50}$ = 498.1$\mu\textrm{g}$/ml), and free radical scavenging effect ($IC_{50}$ = 9$\mu\textrm{g}$/ ml). The aim of the study is to find the natural compounds which have function in skin-lightening, anti-wrinkling and anti-oxidation, with safe and active ingredients in cosmetic.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.233-239
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• 2017

Purpose: This study was performed to quantify the repeat rate of imaging acquisitions based on different clinical examinations, and to assess the prevalence of error types in intraoral bitewing and periapical imaging using a digital complementary metal-oxide-semiconductor(CMOS) intraoral sensor. Materials and Methods: A total of 8,030 intraoral images were retrospectively collected from 3 groups of undergraduate clinical dental students. The type of examination, stage of the procedure, and reasons for repetition were analysed and recorded. The repeat rate was calculated as the total number of repeated images divided by the total number of examinations. The weighted Cohen's kappa for inter- and intra-observer agreement was used after calibration and prior to image analysis. Results: The overall repeat rate on intraoral periapical images was 34.4%. A total of 1,978 repeated periapical images were from endodontic assessment, which included working length estimation (WLE), trial gutta-percha (tGP), obturation, and removal of gutta-percha (rGP). In the endodontic imaging, the highest repeat rate was from WLE (51.9%) followed by tGP (48.5%), obturation (42.2%), and rGP (35.6%). In bitewing images, the repeat rate was 15.1% and poor angulation was identified as the most common cause of error. A substantial level of intra- and inter-observer agreement was achieved. Conclusion: The repeat rates in this study were relatively high, especially for certain clinical procedures, warranting training in optimization techniques and radiation protection. Repeat analysis should be performed from time to time to enhance quality assurance and hence deliver high-quality health services to patients

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.954-963
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• 2017

In this paper, we analyzed the electric/magnetic field distribution and SAR distribution in a human body due to the resonant-type wireless power transfer(WPT) system with an operating frequency of 6.78 MHz. To analyze the field distribution under the unperturbed condition, a prototype system was fabricated and the measured results were compared with the simulation results. For safety during measurement, the available power to the transmitter coil is limited to 1 W. To analyze the induced current density and SAR distribution, a simple human model consisting of three layers, skin, fat, and muscle, was used for the simulation. The electromagnetic wave exposure levels obtained through measurement and simulation were compared with the recommended levels by the ICNIRP.

• Molecular & Cellular Toxicology
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• v.3 no.1
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• pp.23-30
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• 2007

The effects of high energy short wave solar radiation on human skin have received much publicity as the major cause of accelerated skin ageing and of skin cancers. To meet public demand, the cosmetic industry has developed sun protection factor products, which contain a variety of so-called "UV filters", among others benzophenone (BP) and its metabolites are the widely used UV filters. UV filters are also used to prevent UV light from damaging scents and colors in a variety of cosmetics products and to protect of plastic products against light-induced degradation. There are many variants of BP in use. In this respect, to regulate and to evaluate the hazardous effect of BP-type UV filters will be important to environment and human health. The genotoxicity of 7 BP-type UV filters was evaluated in L5178Y $(tk^{+/-})$ mouse lymphoma cells in vitro. BP, benzhydrol, 4-hydroxybenzophenone 2-hydroxy-4-methoxybenzophenone and 2, 4-dihydroxybenzophenone did not induce significant mutation frequencies both in the presence and absence of metabolic activation system. 2, 2'-Dihydroxy-4-methoxybenzophenone appeared the positive results at the highest dose, i.e. 120.4 ${\mu}g/mL$ only in the absence of metabolic activation system. And also, 2, 3, 4-trihydroxybenzophenone revealed a significant increase of mutation frequencies in the range of 138.1-207.2 ${\mu}g/mL$ in the absence of metabolic activation system and 118.3-354.8 ${\mu}g/mL$ in the presence of metabolic activation system. Through the results of MLA with 7 BP-type UV filters in L5178Y cells in vitro, we may provide the important clues on the genotoxic potentials of these BP-type UV filters.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6279-6284
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• 2015

Opisthorchis viverrini (OV)-induced cholangiocarcinoma (CCA) is an important cancer in the Great Mekong region, particularly in Thailand. Limitations of treatment options and the lack of an effective diagnostic tool for early detection of CCA are major concerns for the control of this type of cancer. The aim of the study was to investigate anti-CCA activity of the ethanolic extract of Atractylodes lancea (Thunb.) DC., and the applicability of positron emission tomography-computed tomography (PET-CT) as a tool for detection and monitoring the progression of CCA in Opisthorchis viverrini (OV)/dimethylnitrosamine (DMN)-induced CCA hamsters. Male Syrian hamsters were used for toxicity tests and anti-CCA activity evaluation. Development of CCA was induced by initial feeding of 50 metacercariae of OV, followed by drinking water containing 12.5 ppm of DMN in hamsters. The ethanolic extract of A. lancea (Thunb.) DC. was administered orally for 30 days. PET-CT was performed every 4 weeks after initiation of CCA using 18F-fluorodeoxyglucose ($^{18}F-FDG$). Results from the present study suggest that the ethanolic extract of A. lancea (Thunb.) DC. rhizome exhibited promising anti-CCA activity and safety profile in the OV/DMN-induced hamster model. To successfully apply PET-CT as a tool for early detection of tumor development and progression, modification of radiolabeling approach is required to improve its specificity for CCA cells.

• The Journal of the Korea Contents Association
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• v.13 no.1
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• pp.287-293
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• 2013

Dandelion(Taraxacum officinale), an oriental herbal medicine, has been shown to favorably affect choleretic, antioxidative and protection of gastric mucosa. The protective effects of common dandelion leaf and root extract were investigated by irradiation in Sprague-Dawley rats. Male SD rats, 6weeks, were orally injected with dandelion extract(100mg/kg) for 10days. Immediately after final injection, rats were whole body irradiated with 10Gy used irradiation facility(Elekta Linac, Sweden). At 24h-15days after irradiation, complete blood counted test and apoptosis in jejunal crypt cell. Stimulated recovery by the extract was observed in platelet but was not showed in the erythrocyte and leucocyte. The jejunal crypt cells were protected significantly(p<0.05) and the radiation-induced apoptosis was reduced(p<0.05). The survival rate were carried for 15days, the survival ratio was 15% and 85% for the control and experimental group. Observations intestinal inhibition of cell death, intestinal mucosa and tissue decreased systemic inflammation and vacuole. Base on these data, we propose that dandelion may be a useful radioprotector, especially since it is a relatively nontoxic natural product.