• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.943-948
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• 2021

The purpose of this study was to investigate changes in surface dose due to increased scattering of gamma rays from patients injected with ^99mTc and ¹⁸F, which are radioactive isotopes, in close contact with materials with high atomic number such as the walls of the stable room. Prepare ^99mTc and ¹⁸F by injecting 20 and 10 mCi respectively into the NEMA phantom, and then measuring the surface dose for 60 minutes by positioning the phantom at a height of 1 m above the surface, at a distance of 0, 5 and 10 cm from the wall, and at the same location as the phantom facing the wall. Each experiment was repeated five times for reproducibility of the experiment and one way analysis of variability (ANOVA) was performed for significance testing and Tukey was used as a post-test. The study found that surface doses of 220.268, 287.121, 243.957, and 226.272 mGy were measured at ^99mTc, respectively, in the case of empty space and in the case of 0, 5 and 10 cm, while those of ¹⁸F were measured at 637.111, 724.469, 657.107, and 640.365 mGy, respectively. In order to reduce changes in surface dose depending on the patient's location while waiting, it is necessary to keep the distance from the ground or the wall where the patient is closely adhered to, or install an air mattress, etc., to prevent the scattered lines as much as possible, considering the scattered lines due to the wall etc. in future setup of the patient waiting room and safety room, and in addition to the examination, the external skin width may be reduced.

• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.488-494
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• 2018

To ensure food-safety of mushrooms from radioactive contamination, edible mushroom samples distributed in Gyeonggi province in Korea were collected according to species and country of origin. A total of 284 mushrooms, belonging to 10 species (Lentinula edodes, Pleurotus ostreatus, Pleurotus eryngii, Agaricus bisporus, Flammulina velutipes, Phellinus linteus, Inonotus Obliquus (Chaga), Auricularia auricula-judae, Ganoderma lucidum and Tricholoma matsutake) were subjected to radioactivity testing. The concentration of artificial radionuclides, 131I, 134Cs, and 137Cs, was analyzed using gamma-ray spectrometry. 131I and 134Cs were not detected more than MDA value from all samples. Among 204 domestic mushrooms, however, 137Cs were detected in 0.21~2.58 Bq/kg from six cases (3 Lentinula edodes, 1 Ganoderma lucidum and 2 Tricholoma matsutake), whereas 137Cs were detected in 0.21~53.79 Bq/kg from 38 cases (22 Inonotus Obliquus(Chaga), 14 Phellinus linteus, 1 Lentinula edodes and 1 Tricholoma matsutake) among 80 imported mushrooms. In addition, average concentration of 137Cs in 10 Chaga mushroom-processed products was more than twice as much as dried Chaga mushroom, and maximum concentration was 123.79 Bq/kg. Results suggest that radioactivity monitoring system for imported mushrooms and mushroom-processed products should be continuously intensified to secure food-safety in Korea.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.8-19
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• 2008

The physicochemical properties of soils having high uranium content, located around Duckpyungri in Korea, were investigated and the lab scale soil washing experiments to remove uranium from the soil were preformed with several washing solutions and on various washing conditions. SPLP (Synthetic Precipitation Leaching Procedure), TCLP (Toxicity Characteristic Leaching Procedure), and SEP (Sequential Extraction Procedure) for the soil were conducted and the uranium concentration of the extracted solution in SPLP was higher than Drinking Water Limit of USEPA (30 ${\mu}g$/L), suggesting that the continuous dissolution of uranium from soil by the weak acid rain may generate the environmental pollution around the research area. For the soil washing experiments, the uranium removal efficiency of pH 1 solution for S2 soil was about 80 %, but dramatically decreased as pH of solution was > 2, suggesting that strong acidic solutions are available to remove uranium from the soil. For solutions with 0.1M of HCl and 0.05 M of ${H_2}{SO_4}$, their removal efficiencies at 1 : 1 of soil vs. washing solution ratio were higher than 70%, but the removal efficiencies of acetic acid, and EDTA were below 30%. At 1 : 3 of soil vs. solution, the uranium removal efficiencies of 0.1M HCl, 0.05 M ${H_2}{SO_4}$, and 0.5M citric acid solution increased to 88%, 100%, and 61% respectively. On appropriate washing conditions for S2 soil such as 1 : 3 ratio for the soil vs. solution ratio, 30 minute for washing time, and 2 times continuous washing, TOC (Total Organic Contents) and CEC (Cation Exchange Capacity) for S2 soil were measured before/after soil washing and their XRD (X-Ray Diffraction) and XRF (X-Ray Fluorescence) results were also compared to investigate the change of soil properties after soil washing. TOC and CEC decreased by 55% and 66%, compared to those initial values of S2 soil, suggesting that the soil reclaimant may need to improve the washed soils for the cultivated plants. Results of XRF and XRD showed that the structural change of soil after soil washing was insignificant and the washed soil will be partially used for the further purpose.

• Analytical Science and Technology
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• v.28 no.6
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• pp.377-384
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• 2015

A survey of the artificial radionuclides in rivers and lakes was conducted to investigate their levels in surface water. Water samples were collected at 60 points and analyzed by gamma-ray spectrometry with a measurement time of 10,000 seconds for ¹³⁴Cs, ¹³⁷Cs, and ¹³¹I. The obained values were lower than MDA for all points, except one point for ¹³¹I that was 0.533±0.058 Bq/L. ¹³¹I is known as a radioactive material that occurs frequently in sewage treatment plants. Because it is often used for medical treatments and subject to spreading into the environment due to the excretion from the patients. For the point where ¹³¹I was detected, we conducted additional investigation on the upstream river point and the effluent points of nearby sewage treatment plant to find the source of ¹³¹I. ¹³¹I was not detected at the upstream points of one of the upstream sewage treatment plants but found at the downstream points with the level being 0.257±0.034 to 0.799±0.051 Bq/L, proving the sewage treatment plant was the ¹³¹Isource.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.4
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• pp.307-327
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• 2008

Geochemical study on the rocks and minerals of the Gyeongju low and intermediate level waste repository was carried out in order to provide geochemical data for the safety assessment and geochemical modeling. Polarized microscopy, X-ray diffraction method, chemical analysis for the major and trace elements, scanning electron microscopy(SEM), and stable isotope analysis were applied. Fracture zones are locally developed with various degrees of alteration in the study area. The study area is mainly composed of granodiorite and diorite and their relation is gradational in the field. However, they could be easily distinguished by their chemical property. The granodiorite showed higher $SiO_2$ content and lower MgO and $Fe_2O_3$ contents than the diorite. Variation trends of the major elements of the granodiorite and diorite were plotted on the same line according to the increase of $SiO_2$ content suggesting that they were differentiated from the same magma. Spatial distribution of the various elements showed that the diorite region had lower $SiO_2,\;Al_2O_3,\;Na_2O\;and\;K_2O$ contents, and higher CaO, $Fe_2O_3$ contents than the granodiorite region. Especially, because the differences in the CaO and $Na_2O$ distribution were most distinct and their trends were reciprocal, the chemical variation of the plagioclase of the granitic rocks was the main parameter of the chemical variation of the host rocks in the study area. Identified fracture-filling minerals from the drill core were montmorillonite, zeolite minerals, chlorite, illite, calcite and pyrite. Especially pyrite and laumontite, which are known as indicating minerals of hydrothermal alteration, were widely distributed in the study area indicating that the study area was affected by mineralization and/or hydrothermal alteration. Sulfur isotope analysis for the pyrite and oxygen-hydrogen stable isotope analysis for the clay minerals indicated that they were originated from the magma. Therefore, it is considered that the fracture-filling minerals from the study area were affected by the hydrothermal solution as well as the simply water-rock interaction.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.1
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• pp.33-39
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• 2009

Purpose: The aim of this study is to compare patient's body posture and its position at the time of simulation with one at the treatment room using On-board Imaging (OBI) and CT (CBCT). The detected offsets are compared with position errors of Rando Phantom that are practically applied. After that, Rando Phantom's position is selected by moving couch based on detected deviations. In addition, the errors between real measured values of Rando Phantom position and theoretical ones is compared. And we will evaluate target position's accuracy of KV X-ray imaging's 2D and CBCT's 3D one. Materials and Methods: Using the Rando Phantom (Alderson Research Laboratories Inc. Stanford. CT, USA) which simulated human body's internal structure, we will set up Rando Phantom on the treatment couch after implementing simulation and RTP according to the same ways as the real radioactive treatment. We tested Rando Phantom that are assumed to have accurate position with different 3 methods. We measured setup errors on the axis of X, Y and Z, and got mean standard deviation errors by repeating tests 10 times on each tests. Results: The difference between mean detection error and standard deviation are as follows; lateral 0.4+/-0.3 mm, longitudinal 0.6+/-0.5 mm, vertical 0.4+/-0.2 mm which all within 0~10 mm. The couch shift variable after positioning that are comparable to residual errors are 0.3+/-0.1, 0.5+/-0.1, and 0.3+/-0.1 mm. The mean detection errors by longitudinal shift between 20~40 mm are 0.4+/-0.3 in lateral, 0.6+/-0.5 in longitudinal, 0.5+/-0.3 in vertical direction. The detection errors are all within range of 0.3~0.5 mm. Residual errors are within 0.2~0.5 mm. Each values are mean values based on 3 tests. Conclusion: Phantom is based on treatment couch shift and error within the average 5mm can be gained by the diminution detected by image registration based on OBI and CBCT. Therefore, the selection of target position which depends on OBI and CBCT could be considered as useful.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.235-248
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• 2018

The present work was performed in order to study the effect of competing cation of $Ca^{2+}$ ion on ion exchange of $Cs^+$ on zeolite Y (Si/Al = 1.56). Three single-crystals of fully dehydrated and partially $Cs^+$-exchanged zeolites Y (Si/Al = 1.56) were prepared by the flow method using mixed ion-exchange solutions. The $CsNO_3:Ca(NO_3)_2$ molar ratios of the ion exchange solution were 1 : 1 (crystal 1), 1 : 100 (crystal 2), and 1 : 250 (crystal 3) with a total concentration of 0.05 M. The single-crystals were then vacuum dehydrated at 723 K and $1{\times}10^{-4}Pa$ for 2 days. The structures of the crystals were determined by single-crystal synchrotron X-ray diffraction technique in the cubic space group $Fd{\bar{3}}m$, at 100(1) K. The unit-cell formulas of crystals 1, 2, and 3 were ${\mid}Cs_{21}Ca_{27}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$, ${\mid}Cs_2Ca_{36.5}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$, and ${\mid}Cs_1Ca_{37}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$, respectively. In all three crystals, the $Ca^{2+}$ ions preferred to occupy site I in the D6Rs, with the remainder occupying sites I', II', and II. On the other hand, the significant differences in the fractional distribution of $Cs^+$ ions are observed depending on the intial $Cs^+$ concentrations in given ion exchange solution. In Crystal 1, $Cs^+$ ion are located at sites II', II, III, and III', and in crystal 2, at sites II, IIIa, and IIIb. In crystal 3, $Cs^+$ ions are only located at sites IIIa and IIIb. The degree of $Cs^+$ ion exchange decreased sharply from 28.0 to 2.7 to 1.3 % as the initial $Ca^{2+}$ concentration increases and the $Cs^+$ content decreases.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.119-125
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• 2024

The purpose of this study is to examine the radioprotection effect of mixtures of selenium and arginine for development of radioprotection agents that can minimize radiation damage to police special operation unit in the event of radioactive terrorism. In this study 72 male rats were classified into 4 groups: normal group(NC Group), selenium and arginine mixtures administration group(SeAr Group), radiation exposure group(IR Group), and selenium and arginine mixture administration group followed by radiation exposure(SeAr+IR Group). The 7Gy of X-ray was irradiated to whole body of SD rats. And selenium and arginine were dministered orally at 3mg/kg and 150mg/kg once a day for 14 days. And then hematological and histological analyzes were performed on days 1, 7, and 21 after radiation exposure. In hemotological analysis, significant radioprotection wes observed in lymphocytes(p<0.05) on day 1, platelet(p<0.01) on day 7, red blood cell(p<0.01) on day 21 of radiation exposure in SeAr+IR group compared to IR group. In histological analysis, it was observed that the border of small crypt cells in the small intestine was less collapsed and the length of small crypts was relatively recovered on day 7 and showed that the number of cells and cell wall thickness were better in the prostate on day 21 in SeAr+IR group compared to IR group. Therefore, it is judged that selenium and arginine mixtures have radioprotection effect on blood and tissues due to radiation exposure. it will be helpful for research on radioprotection agents to reduce radiation damage to police special operation unit.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1526-1531
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• 2024

¹³¹I is a fission product produced in a nuclear reactor by irradiating tellurium dioxide, with a half-life of 8.02 day. The most important and widely used method for making ¹³¹I is irradiation using a nuclear reactor and post-irradiation followed by dry distillation. The advantage of the dry distillation process is that the process and the equipment are relatively simple, namely TeO₂ (m.p. 750 ℃), which can withstand heating during reactor irradiation. Based on TeO₂ irradiation by neutron following the technique of dry distillation was explained for production of ¹³¹I on a large scale. A dry distillation followed the radioisotope production operation using the 30 MW GA Siwabessy nuclear reactor to meet national demand. TeO₂ targets are 25 and 50 g irradiated for 87-100 h. The resulting ¹³¹I activity is 20.29339-368.50335GBq. According to the requirements imposed on the radionuclide purity of the preparation, the contribution of ¹³¹I training in the resulting preparation was not less than 99.9 %