• Journal of Radiation Industry
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• v.17 no.2
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• pp.151-160
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• 2023

The International Atomic Energy Agency (IAEA) proposes 11 industries that handle Naturally Occurring Radioactive Material (NORM) that are considered to need management. A water treatment facility is one of the above industries that takes in groundwater and produces drinking water through a water treatment process. Groundwater can accumulate natural radionuclides such as uranium and thorium in raw water by contacting rocks or soil containing natural radionuclides. Therefore, there is a possibility that workers in water treatment facilities will be exposed due to the accumulation of natural radionuclides in the water treatment process. The goal of this study is to evaluate the external radiation dose according to the working type of workers in water treatment facilities. In order to achieve the above goal, the study was conducted by dividing it into 1) analysis of the exposure environment, 2) measurement of the external radiation dose rate 3) evaluation of the external radiation dose. In the stage of analyzing the exposure environment, major processes that are expected to occur significantly were derived. In the measurement stage of the external radiation dose rate, a map of the external radiation dose rate was prepared by measuring the spatial radiation dose rate in major processes. Through this, detailed measurement points were selected considering the movement of workers. In the external radiation dose evaluation stage, the external radiation dose was evaluated based on the previously derived external radiation dose rate and working time. As a result of measuring the external radiation dose rate at the detailed points of water treatment facilities A to C, it was 1.90×10^-1 to 3.75×10⁰ μSv h^-1, and the external radiation dose was analyzed as 3.27×10^-3 to 9.85×10^-2 mSv y^-1. The maximum external radiation dose appeared during the disinfection and cleaning of activated carbon at facility B, and it is judged that natural radionuclides were concentrated in activated carbon. It was found that the external radiation dose of workers in the water treatment facility was less than 1mSv y^-1, which is about 10% of the dose limit for the public. As a result of this study, it was found that the radiological effect of external radiation dose of domestic water treatment facility workers was insignificant. The results are expected to contribute as background data to present optimized safety management measures for domestic NORM industries in the future.

• The Korea Journal of Herbology
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• v.39 no.4
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• pp.29-35
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• 2024

Objectives : Obesity is an imbalance between energy intake and consumption due to overeating and lack of exercise, and if it persists, it increases non-infectious diseases such as high blood pressure, diabetes, and hyperlipidemia. In this study, we tried to investigate the possibility of using Chamaeneron angustifolia (CA) as a material for anti-obesity by confirming the effect of inhibiting lipid differentiation. Methods : We measured the effects of CA extract on oil-red-o staining, cell cytotoxicity evaluation activity using 3T3-L1 cells. Additionally, we assessed fat decomposition and metabolism-related protein expression through Western blot analysis. Results : In this study, the anti-obesity effects of CA extract were experimentally assessed. Results showed significant inhibition of adipocyte differentiation and accumulation at concentrations of 0.05, 0.1, and 0.2 mg/ml of oil-red-o staining, with reductions of 80% or more. CA notably increased the phosphorylation of AMPK protein expression compared to the control group across all concentrations. Additionally, phosphorylation of ACC significantly increased at a concentration of 0.2 mg/ml compared to the control. PPAR-γ, which regulates adipogenesis, exhibited a significant decrease compared to the control, while protein expression of CPT-1, involved in fatty acid oxidation, showed a concentration-dependent increase across all groups. Therefore, CA extract demonstrates potential as a functional material for anti-obesity by increasing the expression of proteins related to fat decomposition and synthesis while decreasing others. Conclusions : These results suggest that CA may also be useful as an anti-obesity functional substance.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.532-537
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• 2024

In this study, wear characteristics and microstructure changes due to changes in alloy composition of Ni-Cr-Mo-V and Ni-Cr-Mo low-alloy steels used in brake discs for transportation system such as aircraft and high-speed trains. As a result of the hardness test, the hardness of C-Mo-V steel was the highest at 39.4±0.9HRc, and the hardness of Ni-Cr-Mo steel was the lowest at 32.4±0.6HRc. The friction coefficient tended to decrease as the vertical load increased. At a vertical load of 1 N, the friction coefficient of Ni-Cr-Mo steel was the highest at 0.842, and at a vertical load of 5 N, Mn-Cr-V steel was the highest at 0.696. Ni-Cr-Mo showed the largest wear scar width, depth, and wear amount, with a width of 711 ㎛, a depth of 8.24 ㎛, and a wear amount of 11 mg under a vertical load of 1 N, and a width of 1,017 ㎛, a depth of 19.17 ㎛, and a wear amount of 17 mg under a vertical load of 5 N. As a result of wear mechanism analysis, ploughing, delamination, and adhesion in all specimens, with plastic deformation being more prominently observed in Ni-Cr-Mo.

• Korean Journal of Agricultural Science
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• v.51 no.2
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• pp.193-203
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• 2024

This study examined the effect of a dietary protein level and age on growth performance, total excreta, and nitrogen balance in laying hen during the growing period for 18 weeks. A total of 96 Hy-Line Brown laying hens were divided into two treatments according to the experimental diets, with each group consisting of six replicates. The experimental diets included: 1) an adequate metabolizable energy and crude protein diet formulated to meet the age and breed specification for Hy-Line Brown containing 21, 18, 16, and 14% dietary CP during 0 to 6, 6 to 12, 12 to 15, 15 to 18 weeks, respectively (CON); 2) 2% CP deficiency from CON diet containing 19, 16, 14, 12% dietary CP during 0 to 6, 6 to 12, 12 to 15, 15 to 18 weeks, respectively (LP). Growth performance, total excreta, and nitrogen balance were investigated for 18 weeks every 3 weeks, and two-way ANOVA was used for statistical analysis of data. The LP group had lower total excreta and N intake than CON group in the whole period of the experiment (p < 0.001). Moreover, birds in the LP group showed lower N excretion than the CON group (p < 0.05). However, the CON group exhibited higher BW, ADG than the LP group (p < 0.001). Application of low-protein diet to laying hens during the growing period reduced N excretion, which contribute to the sustainable development of the laying hen industry by minimizing environmental pollution.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.330-354
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• 2024

In site characterization of high-level radioactive waste, discontinuity(joint) distribution and rock mass classification, which are key evaluation parameters in the rock engineering field, were evaluated using deep boreholes in the Wonju granite and Chuncheon granite, which belong to Mesozoic Jurassic era. To evaluate joint distribution characteristics, fracture zones and joint surfaces extracted from ATV data were used, and major joint sets were evaluated along with joint frequency according to depth, dip direction, and dip. Both the Wonju and Chuncheon granites that were studied showed a tendency for the frequency of joints to increase linearly with depth, and joints with high angles were relatively widely distributed. In addition, relatively large amounts of weathering tended to occur even in deep depth due to groundwater inflow through high-angle joints. RQD values remained consistently low even at considerable depth. Meanwhile, joint groups with low angles showed different joint characteristics from joint sets with high angles. Rock mass classification was performed based on RMR system, and along with rock mass classification for 50 m intervals where uniaxial compressive strength was performed, continuous rock mass classification according to depth was performed using velocity log data and geostatistical techniques. The Wonju granite exhibited a superior rock mass class compared to the Chuncheon granite. In the 50 m interval and continuous rock mass classification, the shallow part of the Wonju granite showed a higher class than the deep part, and the deep part of the Chuncheon granite showed a higher class than the shallow part.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.725-733
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• 2024

This study aims to develop an artificial intelligence-based model for predicting the causes of chemical accidents, utilizing data on 865 chemical accident situations and cases provided by the Chemical Safety Agency under the Ministry of Environment from January 2014 to January 2024. The research involved training the data using six artificial intelligence models and compared evaluation metrics such as accuracy, precision, recall, and F1 score. Based on 356 chemical accident cases from 2020 to 2024, additional training data sets were applied using chemical accident cause investigations and similar accident prevention measures suggested by the Chemical Safety Agency from 2021 to 2022. Through this process, the Multi-Layer Perceptron (MLP) model showed an accuracy of 0.6590 and a precision of 0.6821. the Multi-Layer Perceptron (MLP) model showed an accuracy of 0.6590 and a precision of 0.6821. The Logistic Regression model improved its accuracy from 0.6647 to 0.7778 and its precision from 0.6790 to 0.7992, confirming that the Logistic Regression model is the most effective for predicting the causes of chemical accidents.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1329-1329
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• 2024

As global imperatives shift toward sustainability and carbon neutrality, the construction industry faces an urgent need to address its environmental impact, particularly within steel construction. Despite the increasing adoption of sustainable practices, a detailed understanding of the entire lifecycle emissions of structural steel, especially within the rapidly evolving Chinese market, remains a significant gap. This study introduces a comprehensive life-cycle assessment (LCA) approach to map the carbon footprint of structural steel construction, with a focus on Chinese structural steel as a case study. By adopting a cradle-to-cradle perspective, the research aims to highlight and address the environmental impact across the entire lifecycle of steel used in construction. Specifically, this study will 1) develop a detailed LCA model that encapsulates the environmental impacts of structural steel from production, use, and recycling phases, 2) dentify and analyze carbon hotspots and inefficiencies within the lifecycle of Chinese structural steel, and 3) evaluate and suggest strategies for stakeholders to minimize carbon emissions, moving towards carbon-neutral steel construction. Leveraging a process-based LCA framework, this study captures the material, energy, and emissions flows associated with the lifecycle of structural steel, including steel production, fabrication, transportation, construction, and recycling, in the context of Chinese construction practices. The model is enriched with data from current Chinese steel construction projects, ensuring its accuracy and applicability. Through systematic analysis, the study pinpoints critical phases where carbon emissions can be significantly reduced. Preliminary Results show significant carbon emission sources within the production, fabrication, and transportation phases of Chinese structural steel. These insights are crucial for devising targeted reduction strategies, such as improving production and fabrication efficiency, optimizing logistics, and enhancing material recyclability. The anticipated impact of this research is multi-faceted: providing a robust framework for assessing and managing the carbon footprint of steel construction, guiding industry and policy-makers towards sustainable practices, and setting a precedent for carbon management in steel construction worldwide. This research marks a significant step towards achieving carbon neutrality in steel construction, with a particular focus on Chinese structural steel. Through a comprehensive LCA model, this study offers a deep dive into the lifecycle emissions of steel construction, paving the way for actionable strategies to reduce the environmental impact, contributing to the global endeavor towards carbon-neutral construction.

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4184-4194
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• 2024

New technologies in polymer synthesis and pipe extrusion equipment have led to the commercialization of high-performance, large-diameter, thick-wall high density polyethylene (HDPE) pipes. They have been used in the field of seawater transport and cooling to replace metal pipes, due to their advantages of high corrosion resistance and extensibility. Connection of HDPE pipe is important as it determines the safety of the entire piping system. Butt fusion welding is commonly used for HDPE pipe connection but may cause the formation of weak points in the welded joints, interfering the reliability of the pipeline system in the application of nuclear power plants. At present, there is a lack of research on evaluating the performance of welded joint for large-diameter thick-wall HDPE pipes made by butt fusion-welding. The purpose of this study is to investigate the influence of three different butt fusion-welding processes, i.e., single low pressure (SLP), single high pressure (SHP) and dual low pressure (DLP), by evaluating the performance of their welded joints, including characterizing tensile strength, extensibility, crystallinity and hardness. In specific, a thick-wall HDPE pipe with OD of 812.8 mm and wall thickness of 74 mm which is certified for nuclear safety class was used for study. Representative specimen from the outer, middle and inner part across the wall of the main pipe body and welded joints were taken for testing. Different test methods and specimens were designed to assess the feasibility of evaluating the welding performance from different welding process. The results showed that the mechanical properties of different locations of the welded joints were different, and the tensile strength and fracture energy of the middle part of the joint were lower than that of the inner and outer parts, which could be caused by the difference in the crystallinity and thickness of the melting zone influenced by welding processes, as can be seen from the analysis of DSC test and morphology observation. Hardness testing was conducted on the section of the welded joints, and it revealed that the micromechanical properties of the welded joints in the region of the heat-affected zone were enhanced significantly, which may be due to the annealing effect caused by welding process. In summary, The DLP process resulted in the best extensibility of the welded joints among three processes, suggesting that the joining pressure from welding process plays an important role in affecting the extensibility of the welded joints.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.5
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• pp.499-505
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• 2024

To address the issue of global warming, various regulations and policies for reducing greenhouse gas emissions are being implemented. In this context, the number of countries targeting carbon neutrality, the latter of which entails reducing net carbon emissions to zero, is increasing, and small modular reactors (SMRs) are investigated extensively as a new model for power plants. SMRs, although measuring only 5%-10% of the size of conventional large nuclear power plants, are highly efficient systems that can generate hundreds of megawatts of power. Compared with fossil fuel-based power plants, SMRs generate less carbon emissions and can complement the unstable energy supply from renewable sources. However, the use of SMRs is opposed by local residents owing to the risk of significant radioactive-material leakage when a nuclear-power-plant accident occurs. Hence, floating, small nuclear-power vessels are being investigated and installed in the ocean, thus simplifying the process of securing land, compensating nearby residents, and increasing safety against natural disasters. In this study, the towing stability of SMR power ships is analyzed, and the result shows no significant risk of towing to the destination in sea states 3, 4, and 5.

• Sleep Medicine and Psychophysiology
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• v.17 no.1
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• pp.41-49
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• 2010

Unlike the case of adult obstructive sleep apnea syndrome (OSAS), there was no consistent finding on the changes of sleep architecture in childhood OSAS. Further understanding of the sleep electroencephalogram (EEG) should be needed. Non-linear analysis of EEG is particularly useful in giving us a new perspective and in understanding the brain system. The objective of the current study is to compare the sleep architecture and the scaling exponent (${\alpha}$) from detrended fluctuation analysis (DFA) on sleep EEG between OSAS and normal children. Fifteen normal children (8 boys/7 girls, 6.0${\pm}4.3$2.2 years old) and twelve OSAS children (10 boys/2 girls, 6.4${\pm}4.3$3.4 years old) were studied with polysomnography (PSG). Sleep-related variables and OSAS severity indices were obtained. Scaling exponent of DFA were calculated from the EEG channels (C3/A2, C4/A1, O1/A2, and O2/A1), and compared between normal and OSAS children. No difference in sleep architecture was found between OSAS and normal controls except stage 1 sleep (%) and REM sleep latency (min). Stage 1 sleep (%) was significantly higher and REM latency was longer in OSAS group (9.3${\pm}4.3$4.3%, 181.5${\pm}4.3$59.9 min) than in controls (5.6${\pm}4.3$2.8%, 133.5${\pm}4.3$42.0 min). Scaling exponent (${\alpha}$) showed that sleep EEG of OSAS children also followed the 'longrange temporal correlation' characteristics. Value of ${\alpha}$ increased as sleep stages increased from stage 1 to stage 4. Value of ${\alpha}$ from C3/A2, C4/A1, O1/A2, O2/A1 were significantly lower in OSAS than in control (1.36${\pm}4.3$0.05 vs. 1.41${\pm}4.3$0.04, 1.37${\pm}4.3$0.04 vs. 1.41${\pm}4.3$0.04, 1.37${\pm}4.3$0.05 vs. 1.41${\pm}4.3$0.05, and 1.36${\pm}4.3$0.07 vs. 1.41${\pm}4.3$0.05, p<0.05). Higher stage 1 sleep (%) in OSAS children was consistent finding with OSAS adults. Lower $'{\alpha}'$ in OSAS children suggests decrease of self-organized criticality or the decreased piling-up energy of brain system during sleep in OSAS children.