• Applied Biological Chemistry
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• v.38 no.3
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• pp.263-268
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• 1995

A study was undertaken to compare degradation patterns of carbofuran in soils between submerged and upland moisture conditions [$3-^{14}C$]Carbofuran was treated in each soils at the rate of 1.0 mg/kg (87.8 kBq $^{14}C/50g$ soil) and the time-course analysis for distribution of radioactivity and degradation products were conducted. Differences in the pathway and rate of carbofuran degradation in soils were observed between submerged and upland moisture conditiona major degradation being hydrolysis at 7-C position and oxidation at 3-C position, respectively. Carbofuran showed less persistence in soils of higher moisture contents A significant portion, $24{\sim}39%$ of the total radioactivity, resided in soils as nonextractable residues at 60 days after treatment The nonextractable radioactivity was mainly located in soil organic matter, fulvic acid, humic acid and humin factions Gel filtration chromatography confirmed the incorporation of carbofuran and its degradation products into the organic matter.

• Nuclear Engineering and Technology
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• v.32 no.5
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• pp.477-484
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• 2000

To estimate the degree of intake of $^{238}$ U and $^{232}$ Th through daily diet, a Korean mixed diet sample was prepared after the investigation of the amount of consumption of the daily diet which corresponds to the age of 20 to 60 years. For the analysis of U and Th, the RNAA method was applied. Two standard reference materials were used for quality control and assurance and the analytical results were compared with a certified value. The determination of U and Th in the Korean mixed diet sample was carried out under the same analytical conditions and procedures with SRM. It is found that the concentration of U and Th in a Korean mixed diet was about 35.4 ppb and 3.4 ppb. From these results, the daily intake of $^{238}$ U and $^{232}$ Th by diet is evaluated to be 6.98 and 0.67 $\mu\textrm{g}$ per day, respectively. Radioactivities related to the intake of $^{238}$ U and $^{232}$ Th were estimated to be about 86 mBq and 27 mBq per person per day and the annual dose equivalents from $^{238}$ U and $^{232}$ Th revealed as 3.18 $\mu$Sv and 0.29 $\mu$Sv per person, respectively.

• Journal of Radiation Protection and Research
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• v.8 no.2
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• pp.8-14
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• 1983

The doses to Korean adult by a single and chronic intake of tritiated water are determined using a three compartment model, which describes the retention of tritium radionuclide in body water and in bound organic form in the body. The results show that the total dose of a single intake, using retention half-time for the three-compartment of 9, 30, and 450 days, is 17.64 mrads ($176.4{\mu}Gy$) per 1mCi/kg ($3.7{\times}10^7Bq/kg$) intake, 97% of which is due to tritium in body water and 3% to bound tritium in tissue. In the chronic intake of 1mCi/day($3.7{\times}10^7Bq/day$) tritiated water, the total dose is 85.5 mrad/day(0.855mGy/day). Furthermore, in this study (MPC) a and (MPC)w values of tritium for Korean man are calculated by using the modified formula originated from ICRP Publication-2. From the results, we found that the (MPC) a, w values of ICRP underestimated approximately 50%, the (MPC)a, w values of Korean man must be elevated as high as approximately 50% than that of ICRP.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.13-18
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• 2017

Recently, the number of PET cyclotrons has increased in Korea. A cyclotron mainly produces $^{18}F$, which is used for the production of [$^{18}F$]FDG, a cancer diagnostic radiopharmaceutical. For radiation protection, the discharge control standard under the Nuclear Safety Act limits the radioactive concentration of $^{18}F$ in the exhaust discharged from a nuclear power utilization facility to below $2,000Bq\;m^{-3}$. However, the radioactive concentration of $^{18}F$ discharged during [$^{18}F$]FDG production at the cyclotron facility at Chosun University is maintained at about $1,500Bq\;m^{-3}$ on average, which is 75% of the concentration limit of the discharge control standard, and temporarily exceeds the standard as per the real-time monitoring results. This study evaluated the performance of the exhaust filter unit of the cyclotron facility at Chosun University by assessing the concentration of $^{18}F$ in the exhaust, and an experiment was conducted on the discharge reduction, where $^{18}F$ is discharged without reacting with the FDG precursors during [$^{18}F$]FDG synthesis and is immediately captured by the [$^{18}F$]FDG automatic synthesis unit. Based on the performance evaluation results of the exhaust filter at the cyclotron facility of Chosun University, the measured capture efficiency before and after the filter was found to be 92%. Furthermore, the results of the discharge reduction experiment, where the exhaust $^{18}F$ was immediately captured by the [$^{18}F$]FDG synthesizer, showed a very satisfactory 94.3% reduction in the concentration of discharge compared to the existing discharge concentration.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.425-431
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• 2021

Background: This study evaluated the radon contribution rate through an evaluation of the exhalation rate of radon from building materials. Objectives: This study compared and evaluated the computation of the radon contribution rate based on each different exhalation rate in a building. Methods: The six demonstration houses that are the subject of this study are wall structures or Rahmen structures, and include demonstration houses similar to general residential environments and non-finishing houses with some walls exposed. Results: The highest exhalation rate was found at 62.98 Bq/m² per day from the non-finishing floor, and the second highest exhalation rate was from stone materials at 58.76 Bq/m² per day. Based on this result, investigating the contribution rate of building materials derived from building materials among indoor radon concentrations, house three was the highest at 81.7%, and house one was confirmed to be 33.96%. Conclusions: It can be judged that the effect of exposed concrete and stone is high, and that it is possible to reduce radon emitted from indoor building structures by controlling the indoor materials.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.489-494
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• 2021

In this study, radioactivity quantitative analysis was performed on radon contained in cigarette, and the effective dose was calculated using the result value to determine the amount of exposure caused by smoking. A total of 5 types of cigarettes were sampled. Cigarette smoke was collected by using activated carbon, and tobacco were measured by homogenizing for quantitative analysis. For each sample, Bi-214 and Pb-214 were subjected to gamma nuclide analysis to observe the uranium-based radioactive material contained in cigarette, and a measurement time of 30,000 seconds was set for the sample based on the results of previous studies. As a result of measuring the radioactivity of tobacco, a maximum of 0.715 Bq/kg was derived, and in the case of cigarette smoke measured using activated carbon, a maximum of 3.652 Bq/kg was derived. Using this measurement, the average effective dose to the lungs is 0.938 mSv/y, and it was found that there is a possibility of receiving exposure up to 1.099 mSv/y depending on the type of tobacco. It was found that the exposure dose due to cigarette occupies a large proportion of the annual effective dose limit for the general public. Therefore, more diverse studies on radioactive substances in cigarette are needed, and measures to monitor and reduce the incidental exposure to radon should be established.

• Journal of Biomedical Engineering Research
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• v.39 no.6
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• pp.243-249
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• 2018

The indoor radon concentration was measured in the lecture room of the university and the radon concentration was converted to the amount related to the radon exposure using the dose conversion convention and compared with the reference levels for the radon concentration control. The effect of indoor radon inhalation was evaluated by estimating the life effective dose and the risk of exposure. To measure the radon concentration, measurements were made with a radon meter and a dedicated analysis Capture Ver. 5.5 program in a university lecture room from January to February 2018. The radon concentration measurement was carried out for 5 consecutive hours for 24 hours after keeping the airtight condition for 12 hours before the measurement. Radon exposure risk was calculated using the radon dose and dose conversion factor. Indoor radon concentration, radon exposure risk, and annual effective dose were found within the 95% confidence interval as the minimum and maximum boundary ranges. The radon concentration in the lecture room was $43.1-79.1Bq/m^3$, and the maximum boundary range within the 95% confidence interval was $77.7Bq/m^3$. The annual effective dose was estimated to be 0.20-0.36 mSv/y (mean 0.28 mSv/y). The life-time effective dose was estimated to be 0.66-1.18 mSv (mean $0.93{\pm}0.08mSv$). Life effective doses were estimated to be 0.88-0.99 mSv and radon exposure risk was estimated to be 12.4 out of 10.9 per 100,000. Radon concentration was measured, dose effective dose was evaluated using dose conversion convention, and degree of health hazard by indoor radon exposure was evaluated by predicting radon exposure risk using nominal hazard coefficient. It was concluded that indoor living environment could be applied to other specific exposure situations.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.2
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• pp.159-166
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• 2021

Nicotinamide adenine dinucleotide phosphate oxidases (NOXs) are the major enzymatic source of reactive oxygen species (ROS). NOX2 and NOX4 are expressed in the heart but its role in hypoxia-induced atrial natriuretic peptide (ANP) secretion is unclear. This study investigated the effect of NOX on ANP secretion induced by hypoxia in isolated beating rat atria. The results showed that hypoxia significantly upregulated NOX4 but not NOX2 expression, which was completely abolished by endothelin-1 (ET-1) type A and B receptor antagonists BQ123 (0.3 μM) and BQ788 (0.3 μM). ET-1-upregulated NOX4 expression was also blocked by antagonists of secreted phospholipase A2 (sPLA2; varespladib, 5.0 μM) and cytosolic PLA2 (cPLA2; CAY10650, 120.0 nM), and ET-1-induced cPLA2 expression was inhibited by varespladib under normoxia. Moreover, hypoxia-increased ANP secretion was evidently attenuated by the NOX4 antagonist GLX351322 (35.0 μM) and inhibitor of ROS N-Acetyl-D-cysteine (NAC, 15.0 mM), and hypoxia-increased production of ROS was blocked by GLX351322. In addition, hypoxia markedly upregulated Src expression, which was blocked by ET receptors, NOX4, and ROS antagonists. ET-1-increased Src expression was also inhibited by NAC under normoxia. Furthermore, hypoxia-activated extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (Akt) were completely abolished by Src inhibitor 1 (1.0 μM), and hypoxia-increased GATA4 was inhibited by the ERK1/2 and Akt antagonists PD98059 (10.0 μM) and LY294002 (10.0 μM), respectively. However, hypoxia-induced ANP secretion was substantially inhibited by Src inhibitor. These results indicate that NOX4/Src modulated by ET-1 regulates ANP secretion by activating ERK1/2 and Akt/GATA4 signaling in isolated beating rat hypoxic atria.

• Journal of Radiation Protection and Research
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• v.46 no.4
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• pp.178-183
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• 2021

Background: This study was carried out to provide environmental transfer parameter values to estimate activity concentrations of these radionuclides in agricultural crops when direct contamination occurred. Materials and Methods: Mass interception fractions (F_Bs) and weathering half-lives (T_ws) of ¹³¹I and radiocesium were calculated using openly available monitoring data obtained after the Fukushima Daiichi Nuclear Power Plant accident. F_B is the ratio between the initial radioactivity concentration of a radionuclide retained by the edible part of the plant (Bq·kg^-1 fresh weight [FW]) and the amount of deposited radionuclide in that area (Bq·m^-2). T_w values can be calculated using activity concentrations of crops decreased with time after the initial contamination. Results and Discussion: Calculated F_B and T_w values for ¹³¹I and radiocesium were mostly obtained for leafy vegetables. The analytical results showed that there was no difference of F_Bs between ¹³¹I and radiocesium by t-test; geometric mean values for leafy vegetables cultivated under outdoor conditions were 0.058 and 0.12 m²·kg^-1 FW, respectively. Geometric mean T_w value of ¹³¹I in leafy vegetables grown under outdoor conditions was 8.6 days, and that of radiocesium was 6.6 days; there was no significant difference between T_w values of these radionuclides by Wilcoxon rank sum test. Conclusion: There was no difference between ¹³¹I and radiocesium for F_Bs and T_ws. By using these factors, we would be able to carry out a rough estimation of the activity concentrations of ¹³¹I and radiocesium in the edible part of leafy crops when a nuclear accident occurred.

• Journal of Radiation Protection and Research
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• v.46 no.2
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• pp.58-65
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• 2021

Background: The evaluation of skyshine distribution, release of airborne radioactive nuclides, and soil activation and groundwater migration were required for radiological assessment of the impact on the environment surrounding In-Flight (IF)-system facility of the RAON (Rare isotope Accelerator complex for ON-line experiment) accelerator complex. Materials and Methods: Monte Carlo simulation by MCNPX code was used for evaluation of skyshine and activation analysis for air and soil. The concentration model was applied in the estimation of the groundwater migration of radionuclides in soil. Results and Discussion: The skyshine dose rates at 1 km from the facility were evaluated as 1.62 × 10^-3 μSv·hr^-1. The annual releases of ³H and ¹⁴C were calculated as 9.62 × 10^-5 mg and 1.19 × 10^-1 mg, respectively. The concentrations of ³H and ²²Na in drinking water were estimated as 1.22 × 10^-1 Bq·cm^-3 and 8.25 × 10^-3 Bq·cm^-3, respectively. Conclusion: Radiological assessment of environmental impact on the IF-facility of RAON was performed through evaluation of skyshine dose distribution, evaluation of annual emission of long-lived radionuclides in the air and estimation of soil activation and groundwater migration of radionuclides. As a result, much lower exposure than the limit value for the public, 1 mSv·yr^-1, is expected during operation of the IF-facility.