• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.28-39
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• 1998

This study investigated the natural convection and radiation in a rectangular enclosure with ceiling vent experimentally and numerically. A heat source is located on the center of the bottom surface. The analysis was peformed a pure convection and is combination of natural convection and radiation. The shape of the considered two dimensional model is a square whose center of ceiling($30\%$) is opened. The numerical simulations are carried out for the pure natural convection case and the combined heat transfer case by using the SIMPLE algorithm. For the turbulent flow, Reynolds stresses are closed by the standard $k-{\epsilon}$ model and the wall function is used to determine the wall boundary conditions. The experiment was performed on the same geometrical shape as the computations. The radiative heat transfer is analized by the S-N discrete ordinates method. The results of pure natural convection are compared with those of combined heat transfer by the velocity vectors, stream lines, isothermal lines. The results obtained are as follows 1. Comparing the results of pure convection with those of the combined convection-radiation through the shape of stream lines, isothermal lines are similar to each other. 2. The temperature fields obtained by numerical method are compared to those obtained by experimental one, and it is found that they are showed mean relative error $8.5\%$. 3. Visualization bt smoke is similar to computational results.

• Journal of radiological science and technology
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• v.46 no.1
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• pp.23-28
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• 2023

The purpose of this study is to see the radiation protection effect of the oral injected Dendranthema zawadskii var. latilobum (Maxim.) Kitam. extracts on the small intestine and uterus of female SD Rat as a natural radiation protection agent. The experimental group was divided into four groups: Normal Control group (NC group), Injected Dendranthema zawadskii var. latilobum (Maxim.) Kitam. extracts group (DZ group), irradiated group after injecting Dendranthema zawadskii var. latilobum (Maxim.) Kitam. extracts (DZ+IR group). The whole body of SD Rat was irradiated with gamma-ray 10Gy, and the administration of oral Dendranthema zawadskii var. latilobum (Maxim.) Kitam. Extract was 2 cc (71.56 mg/day/kg) once a day for 2 weeks. For this study, chages in blood cell levels, SOD assay, small intestine and uterus were observed. In the 21st white blood cell level, the DZ+IR group recovered to a normal level, and the IR group didn't. The IR group villus length was lower than other groups on Day 1. IR group was partially recovered, and DZ+IR group was recovered like the NC group on Day 21. In the case of the first-day endometrium, the IR group was thin and the boundary was cloudy, and the DZ+IR group was thicker and the boundary was clearer than the IR group. Day 21 IR group still did not recover, and DZ+IR group recovered like NC group. This is believed to have radiation protection effects in the blood cells and small intestine and uterus of the irradiated female SD Rat, and is expected to be useful for the study of natural radiation protection materials.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.367-368
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• 2019

• The Korean Journal of Food And Nutrition
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• v.28 no.3
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• pp.486-492
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• 2015

This study was conducted to provide fundamental data on the awareness of radiation, specifically the differences between general awareness, psychological state and harmful effects. Data was collected from 334 University students in the Chungbuk region through a self-administered questionnaire. According to the results of the reliability and factor analysis, the awareness of radiation was 2.80, with a Cronbach alpha coefficient of 0.815 and KMO of 0.798. Factor analysis extracted three components of the awareness of radiation, which we named general awareness (factor 1), psychological state (factor 2), and harmful effect (factor 3). There were significant differences in the general awareness of natural radiation and radiation-containing foods (p<0.05), whereas no significant differences were found in the general awareness of radiation food supply (p>0.05). Also, the psychological state showed a significant difference in exposure inspection, future exposure, and radiation-containing food (p<0.05), whereas no significant differences were found in the refusal of radiation inspection (p>0.05). The harmful effects showed a significant difference in the rejection of radiation (p<0.05), but no significant differences in the cancer and genetic effects, diseases and physical harmfulness (p>0.05). A significant positive result (p<0.05) was found for the psychological state according to the harmful effects of radiation. Based on this study, detailed and continuous education must be accomplished by increasing the awareness of radiation and the acceptance level, conveying a proper understanding of radiation and assisting subjects with receiving the information they desire through various educational mediums.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.1-11
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• 2023

To protect people and the environment from environmental radiation, the Act on Protective Action Guidelines against Radiation in the Natural Environment was formulated in Korea in 2011. This law regulates matters related to radiation safety that can be encountered in life. In accordance with this law, radiation monitoring equipment is operated at major airports and ports across the country, ensuring radiation monitoring of imported cargo. Currently, six ministries conduct radiation monitoring of imported cargo: the Nuclear Safety and Security Commission; the Korea Customs Service; the Ministry of Food and Drug Safety; the Ministry of Environment; the Ministry of Agriculture, Food and Rural Affairs; and the Korea Forest Service. Each ministry designates the relevant cargo items for radiation monitoring. The objective of this study was to comprehensively review the Korean radiation monitoring system for imported cargo and identify the areas and scopes of improvement. This paper also proposes a new law and an integrated supervision plan, which involves establishing a dedicated department to enhance the efficiency and professionalism of the national radiation monitoring system for imported cargo. The review will contribute to the development of a more sophisticated national radiation monitoring system for imported cargo.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.65-73
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• 2016

The aim of this study was to investigate the UV-resistance of radiation-resistant bacteria isolated from the water of Han River, South Korea. The water sample was irradiated with 3 kGy gamma radiation prior to isolation. Radiation-resistant bacterial strains were isolated by standard serial dilution method on R2A and 1/10 diluted R2A agar. The resulting purely isolated 60 cultures of bacteria were analysed for UV resistance and used in further studies. Based on the comparative analyses of 16S rRNA gene sequences, the bacterial isolates were divided into 3 phyla (4 genera): the phylum Deinococcus-Thermus (the genus Deinococcus) was 61.7%, Bacteroidetes (Hymenobacter and Spirosoma) was 23.4%, and Firmicutes (Exiguobacterium) was 15%. The results suggested that twenty-nine isolates are candidates new species belonging to Deinococcus, Hymenobacter, and Spirosoma, or other new genera. Nine bacterial strains were selected among the novel candidates and the UV-resistance analysis was conducted. All the candidate bacterial strains showed high UV resistance, similar to that of D. radiodurans R1.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1599-1605
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• 2011

To evaluate heat environment surrounding plants diurnal change of leaf temperature in the broad-leaved deciduous and evergreen trees was measured with microclimatic environmental factors including global solar radiation, and upward and downward long wave radiation. Maximum daily solar radiation was 961.2 and 976.3 w/$m^2$ in August 9 and 23, respectively. Upward long wave radiation was slightly higher than downward long wave radiation, showing 404.2 w/$m^2$ in August 9 and 394.5 w/$m^2$ in August 23. In addition, daily maximum vapor pressure deficit was 5.42 and 6.84 kPa in August 9 and 23, respectively, indicating high evaporative demand. Quercus glauca and Acer mono was differently responded to changing light regimes. On August 9, leaf temperature at the top-positioned leaves of Acer plants was higher than air temperature as well as those of Quercus plants in the morning. This indicates that stomata in Acer plants were closed by heat stress or water stress in the morning, while Quercus plant maintained active transpiration by opening stomata. These results indicated that improved light regimes such as gap opening in the closed forest may not always affect positively in the physiology of understory plants.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.3
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• pp.84-93
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• 2003

Photoreactivation of microorganism following UV-disinfection is one of the research topics of interest in assessing the UV-disinfection performance. Apparent photoreactivation was examined under fluorescent lamp and solar radiation as well as in darkness. Total coliform, fecal coliform, and Escherichia coli were used as indicator microorganisms, and their concentration was monitored with time after UV-disinfection. Under the darkness, their initial concentration of 10∼30 MPN/100 mL increased to the level of 100 MPN/100 mL after 24 hours, which implied that part of damaged microorganisms by UV-disinfection might be repairable with time. Under the fluorescent lamp, photoreactivation was more apparent that their concentration increased up to 1,000 MPN/100 mL which might significantly impair the water uses specially in reuse of reclaimed wastewater. However, their concentration further decreased down to below 2 MPN/100 mL under the solar radiation primarily due to additional disinfection by solar radiation rather than photoreactivation. Samples not disinfected by UV-disinfection also demonstrated substantial decrease of their concentration under solar radiation from about 5,000 MPN/100 mL to less than 30 MPN/100 mL in 24 hours. But direct reuse of effluent without disinfection is not recommended because natural decay by solar radiation may take time and be affected by climatic conditions. The result suggests that photoreactivation of pathogenic microorganisms may not be concerned in agricultural reuse of reclaimed wastewater because solar radiation may provide further disinfection after UV-disinfection.

• Journal of Korean Biological Nursing Science
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• v.4 no.2
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• pp.59-68
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• 2002

The purpose of this study was to determine the effect of exercise program on natural killer cell cytotoxic activity(NKCA) in breast cancer patients who had been radiation therapy after surgery. The subjects in the experimental group consisted of 11 breast cancer patients, while the subjects in the control group consisted of 15. Subjects in the experimental group participated in exercise program for 8 weeks. Exercise program consisted of shoulder stretching, arm weight training and treadmill walking exercise. They started to exercise on treadmill for 20 minutes per day, 3 times a week at 40% of maximum heart rate, and increased intensity and duration of exercise so that they were running 30 minutes/day at 60% of maximum heart rate from the 3rd week to the 8th week. Natural killer cell cytotoxic activity were determined before and after the exercise program. For measuring the natural killer cell cytotoxic activity, 8ml to 10ml blood was collected from the subjects. Mononuclear cell was isolated by centrifuge of the blood and cultured by putting $Cr^{51}$, and reacted with target cell, K562 cell. Baseline demographic and medical data were compared between groups with the Fisher's exact test and Mann-Whitney U test. For effects of the exercise program, repeated measures ANOVA was used. The result was as follows; Natural killer cell cytotoxic activity(NKCA) in experimental group comparing with control group significantly increased after the exercise program in case of effector cell : target cell ratio is 100 : 1(p<0.05). The above result suggest that the exercise program for breast cancer patients undergoing radiation therapy after breast surgery may increase the natural killer cell cytotoxic activity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.385-390
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• 2012

A radial heat sink, adopted to LED(light emitting diode) downlight, was optimized. Discrete transfer radiation model (DTRM) was used to calculate radiation heat transfer, and numerical model was verified with experimental results. The effects of number of fin, long fin length and middle fin length on overall thermal resistance and radiation heat transfer were analyzed. As the emissivity increased, thermal resistance decreased due to the increment of radiation heat transfer. The radial heat sink was optimized and optimum number of long fins is 19~28, optimum length of long fin is about half of radius of heat fink and optimum fin ratio is 0.4~0.7.