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Hydrogeochemical Factors Related to Uranium Concentration Levels in Granitic Aquifers in Korea
YeoJin Ju,Sanghoon Lee,Min-Hoon Baik,Ji-Hun Ryu 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
Uranium (U) is a hazardous material that can lead to both chemical and radiological toxicity, including kidney damage and health issues associated with radiation exposure. In South Korea. In Korea, where shallow weathered granitic aquifers are widespread, several previous studies have reported high levels of radioactivity in shallow groundwater. This ultimately led to the closure of 60 out of 4,140 groundwater production wells in South Korea. In this study, we examined aquifers currently dedicated to drinking water supply and investigated a dataset of 11,225 records encompassing 103 environmental parameters, based on the random forest classifier. This dataset comprises 80 physical parameters associated with the hydraulic system and 23 chemical parameters linked to water-rock interactions. Among the hydraulic parameters, the presence of a coarse loamy texture in the subsoil displayed a notable positive relationship with the concentration of uranium, implying that it plays a significant role in forming redox conditions for the leaching of uranium from host rocks. Fluorine (F), a major product of water-rock interaction in granitic aquifers, exhibited a positive correlation with the distribution of uranium concentrations. The positive relationship between F concentration and uranium levels suggests that the dissolved uranium originates from groundwater interacting with granites. In conclusion, our findings indicate that two key factors, namely the infiltration capacity of soil layers and the aqueous speciation in groundwater resulting from interactions with local solids, play important roles in determining uranium concentrations in granitic aquifers.
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YeoJin Ju,Dong-Chan Koh,Hong-Il Kwon,Dong-Hun Kim 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
The quality of river-side groundwater is dependent on the complicated hydrodynamic conditions, such as the convergent flow setting and stream-aquifer interactions. To understand the water mass balance and the nutrient dynamics in agricultural riparian zones, we used water and nitrate stable isotopes, inert gas tracers, 16S rRNA gene analysis and land use information with the aid of regional scale chemical data. Water samples were collected from the river-side granitic aquifers, which recently shows significant water level drawdown (-0.8 m/y). Heterogeneous river water infiltration into granitic aquifer was identified using the Bayesian mixing model (7.1% to 48.6%) considering uncertainties of SiO₂(aq) and d<SUP>18</SUP>O in regional groundwater. The stream-aquifer interaction was also demonstrated by the spatial distribution of He tracer. The major source of the N-nutrient was manure/sewage from dry farmland and residential area, with their land use (area, %) explained the majority of NO₃ distribution in groundwater (R²=0.935). δ<SUP>15</SUP>N, δ<SUP>18</SUP>O and NO₃<SUP>-</SUP> distributions revealed that the denitrification process was dominant in the river-side groundwater, generating N2(g). The correlation between N2(g) and paddy field (area, %), implied the importance of low permeable layers for natural attenuation. Anammox bacteria were present in multiple locations of the river-side groundwater, implying the efficient attenuation of nitrate in the site. Distribution of He and Ar indicated the aquifers were not closed for the N transformation process with loss of the generated N2(g) up to 21%. The N2(g) loss in the riverside aquifers is likely to be related to the pressure reduction induced by heavy groundwater pumping in this area.
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The Effect of Mindfulness on the Stress Management of DISASTER Era
Yeojin Lim,Jeumnam Kim J-INSTITUTE 2021 International Journal of Human & Disaster Vol.6 No.3
Purpose: The purpose of this study is to verify the effectiveness of mindfulness in the stress management of military leaders. In the long-term situation in the COVID-19, the military leaders are increasingly anxious and also they are often exposed to extreme stress environments. Considering this situation, the contents of mindfulness were combined in leadership coaching program, and the military leaders were able to confirm the psychological well-being and stress relief after the mindfulness program before the lecture. Method: For this purpose, the program was designed based on the results of previous studies and needs sur-veys, and the problems revealed through expert verification and preliminary program implementation were re-vised and supplemented. The effects of coaching lectures on subjective well-being and psychological well-being were verified by arranging 8 military leaders participants in the experimental group, the comparative group(the psychological well-being program) and the control group, respectively, with the students participating in the main executive course. Results: As a result, the experimental group showed significant differences in both subjective well-being and psychological well-being of the comparative group and the control group. To measure the cognitive factors of subjective well-being, the Satisfaction With Life Scale(SWLS) developed by Diener et al.(1985) and adapted by Ryu Yeon-ji(1996) was used. This scale consists of five questions in total, and consists of seven-point scales. The emotional factors were used the Index of General Effect, which was translated by Lee Soo Il(1997). This scale is a tool to measure positive-negative emotional aspects, with a total of 9 questions, each of which is paired with two adjectives and a seven-point scale. In this study, Cronbach s value was .83 and Cronbach s value of emotional well-being was .86. Conclusion: In the analysis of participants experience reports and the observations of the hosts, it was con-firmed that the experimental group who participated in the psychological well-being promotion program for the stress management of the military leaders had a positive change in the psychological well-being improvement. However, this study has a limitation in generalizing the results of the study to all military leaders because it causes sampling errors by recruiting applicants, which is a non-probable sampling method, in the recruitment of research subjects. In addition, since only 8 people were assigned to each group, it is necessary to conduct a study that has sufficient number of people considering external validity.
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Investigation on the Safety of Boeun U Ore Using Multiple Environmental Tracers
YeoJin Ju,Min Hoon Baik,Seung Yeop Lee,Kang-Kun Lee,Dugin Kaown,Dongbok Shin,Ji-Hun Ryu 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
Uranium inventory in Boeun aquifer is facing the artificial reservoir that intended for supplying water to nearby cities (40-70 m apart) where, toxic radionuclides might mobile and enter the reservoir. In order to understand U mobility in the system, groundwater and fracture filling materials (FFMs) were analyzed for microbial signatures, C, O, Fe, S and U-series isotopes. The δ18O-H2O and 14C signatures suggested groundwater was originated from upland recharges dominantly and not affected by mixing with the surface water. However, the 234U/238U activity ratios (ARs) and 230Th/234U ARs in FFMs ranged from 0.93 to 1.67 and from 0.22 to 1.97, respectively, indicating that U was mobile along the fractures. In shallow FFMs, the U accumulations (~157 mg/kg) were found with Fe enrichments (~226798 mg/kg) and anomalies of δ56Fe and δ57Fe, implied U mobility in shallow depths was associated with Fe-rich environment. Also, in the shallow depths, Fe-oxidizers, Gallionella was prevailing in groundwater while Acidovorax was abundant near U ore depth. The Fe-rich environment in shallow depths was formed by pyrite dissolution, demonstrated using δ34S-SO4 and δ18O-SO4 distribution. Conclusively, the Fe-rich aquifer was capable of immobilizing the dissolved U through biotic and abiotic processes, without significant discharge into the nearby reservoir.
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( Yeojin Lee ),( Jae Kyung Lee ),( Sanghwa Kim ),( Yeon Ju Lee ),( Kichang Han ),( Man-deuk Kim ),( Heeyon Kim ),( Seok Kyo Seo ) 대한산부인과학회 2022 대한산부인과학회 학술대회 Vol.108 No.-
Objective: Although the surgical treatment remains gold standared in endometrioma, ovarian reserve is injured after the hemostasis and excision of the cyst. Catheter-directed ethanol sclerotherpy is known to affect the ovarian function less, increase efficacy, and reduce complications. This study aims to investigate the changes in ovarian reserve after catheter-directed ethanol sclerotherpy in recurrent endometrioma. Methods: Electronic medical records and pictures in patients with endometrioma who underwent catheter-directed ethanol sclerotherpy were obtainted in single institution from August 2014 to April 2022. Patient with aged >18 years old and AMH level >1.0 and <5.0 were enrolled in the study and age, BMI, cyst diameter, unilaterality, number of loculation and AMH level and CA-125 level before and after 1month, 6month, 1year and 2year of sclerotherapy were obtained. Results: 139 patients were enrolled in the study under IRB. There was significant differnece in AMH level before sclerotherapy in primary and recurrent endometrioma(2.68 vs. 2.04, p-value=0.011). However, there was no statistically significant difference in delta value of AMH after sclerotherapy in primary and recurrent endometrioma in 1month, 6month, 1year and 2year after sclerotherpy(91.78% vs. 96.14%, 74.75% vs. 81.58%, 83.98% vs. 65.79%, 97.08% vs. 52.52%, with p-value=0.593, 0.695, 0.217, 0.069, respectively). Also, this results were consistent regardless of unilaterality and loculation and CA-125 level showed no differerence between primary and recurrent endometrioma on every 1month, 6month, 1year and 2year after sclerotherpy. Conclusion: The effect of Catheter-directed ethanol sclerotherpy on ovarian reserve is not inferior in recurrent endometrioma compared to primary endometrima. Since sclerotherapy is known to less deteriorate the ovarian function than surgical removal of endometrioma, clinician could consider this as the first-line therapy in patient with recurrent endometrioma.
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Heat Treatment and TG-DTA Analysis of Uranyl Nitrate and Uranium Oxides
Yeojin Kim,Gun Young Yoon,Gyun Seob Song,Yulim Lee,Jae Hak Cheong,Sangjoon Ahn,Jaeyeong Park,Won Pyo Jeong,Seungyeon Choi,Kwang Heon Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
The solid-state chemistry of uranium is essential to the nuclear fuel cycle. Uranyl nitrate is a key compound that is produced at various stages of the nuclear fuel cycle, both in front-end and backend cycles. It is typically formed by dissolving spent nuclear fuel in nitric acid or through a wet conversion process for the preparation of UF6. Additionally, uranium oxides are a primary consideration in the nuclear fuel cycle because they are the most commonly used nuclear fuel in commercial nuclear reactors. Therefore, it is crucial to understand the oxidation and thermal behavior of uranium oxides and uranyl nitrates. Under the ‘2023 Nuclear Global Researcher Training Program for the Back-end Nuclear Fuel Cycle,’ supported by KONICOF, several experiments were conducted at IMRAM (Institute of Multidisciplinary Research for Advanced Materials) at Tohoku University. First, the recovery ratio of uranium was analyzed during the synthesis of uranyl nitrate by dissolving the actual radioisotope, U3O8, in a nitric acid solution. Second, thermogravimetric-differential thermal analysis (TG-DTA) of uranyl nitrate (UO2(NO3)2) and hyper-stoichiometric uranium dioxide (UO2+X) was performed. The enthalpy change was discussed to confirm the mechanism of thermal decomposition of uranyl nitrate under heating conditions and to determine the chemical hydrate form of uranyl nitrate. In the case of UO2+X, the value of ‘x’ was determined through the calculation of weight change data, and the initial form was verified using the phase diagram for the U-O system. Finally, the formation of a few UO2+X compounds was observed with heat treatment of uranyl nitrate and uranium dioxide at different temperature intervals (450°C-600°C). As a result of these studies, a deeper understanding of the thermal and chemical behavior of uranium compounds was achieved. This knowledge is vital for improving the efficiency and safety of nuclear fuel cycle processes and contributes to advancements in nuclear science and technology.
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Yeojin Kim,Jiseon Yang,Dohyoung Rim,Uran Oh The Institute of Internet 2023 International journal of advanced smart convergenc Vol.12 No.2
Given the surge in the elderly population, and increasing in dementia cases, there is a growing interest in digital therapies that facilitate steady remote treatment. However, in the cognitive assessment of digital therapies through clinical trials, the absence of log data as an essential evaluation factor is a significant issue. To address this, we propose a solution of utilizing weighted derived variables based on high-importance variables' accuracy in log data utilization as an indirect cognitive assessment factor for digital therapies. We have validated the effectiveness of this approach using machine learning techniques such as XGBoost, LGBM, and CatBoost. Thus, we suggest the use of log data as a rapid and indirect cognitive evaluation factor for digital therapy users.
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