• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.423-429
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• 2021

The investigation of the utilization of enriched ²⁰⁸Pb as a coolant to enhance the performance of a long-life fast reactor with a Modified CANDLE (Constant Axial shape of Neutron flux, nuclide densities, and power shape During Life of Energy production) burnup scheme has performed. The analyzes were performed on a reactor with thermal power of 800 MegaWatt Thermal (MWTh) with a refueling process every 15 years. Uranium Nitride (enriched ¹⁵N), ²⁰⁸Pb, and High-Cr martensitic steel HT-9 were employed as fuel, coolant, and cladding materials, respectively. One of the Pb-nat isotopes, ²⁰⁸Pb, has the smallest neutron capture cross-section (0.23 mb) among other liquid metal coolants. Furthermore, the neutron-producing cross-section (n, 2n) of ²⁰⁸Pb is larger than sodium (Na). On the other hand, the inelastic scattering energy threshold of ²⁰⁸Pb is the highest among Na, ^natPb, and Bi. The small inelastic scattering cross-section of ²⁰⁸Pb can harden the neutron energy spectrum. Therefore, ²⁰⁸Pb is a better neutron multiplier than any other liquid metal coolant. The excess neutrons cause more production than consumption of ²³⁹Pu. Hence, it can reduce the initial fuel loading of the reactor. The selective photoreaction process was developing to obtain enriched ²⁰⁸Pb. The neutronic was calculated using SRAC and JENDL 4.0 as a nuclear data library. We obtained that the modified CANDLE reactor with enriched ²⁰⁸Pb as coolant and reflector has the highest k-eff among all reactors. Meanwhile, the ^natPb cooled reactor has the lowest k-eff. Thus, the utilization of the enriched ²⁰⁸Pb as the coolant can reduce reactor initial fuel loading. Moreover, the enriched ²⁰⁸Pb-cooled reactor has the smallest power peaking factor among all reactors. Therefore, the enriched ²⁰⁸Pb can enhance the performance of a long-life Modified CANDLE fast reactor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.411-416
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• 2020

Field investigations of forests are carried out by writing measured data by hand, and it is a hassle to reorganize the results after a field survey. In this study, a method using object modeling and augmented reality (AR) was applied in a test forest to increase the efficiency of a field investigations. Using a 3D laser scanner, data on were acquired 387 trees within an area of 1 ha at the study site. The coordinates, height, and diameter were calculated through object extraction and modeling of a tree. The proposed can reduce the time required to acquire data in the field and can be used as basic data for building related systems. In addition, the modeling results of trees and a survey using GNSS and AR techniques can be used check coordinates, labor, and attribute information, such as the chest height diameter of the trees being surveyed in the field. The shortcomings of the survey method could be improved. In the future, the method could greatly improve the efficiency of tree surveys and monitoring by reducing the manpower and time required for field surveys.

• Journal of Animal Science and Technology
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• v.63 no.6
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• pp.1232-1246
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• 2021

Recently, the cattle genome sequence has been completed, followed by developing a commercial single nucleotide polymorphism (SNP) chip panel in the animal genome industry. In order to increase statistical power for detecting quantitative trait locus (QTL), a number of animals should be genotyped. However, a high-density chip for many animals would be increasing the genotyping cost. Therefore, statistical inference of genotype imputation (low-density chip to high-density) will be useful in the animal industry. The purpose of this study is to investigate the effect of the reference population size and marker density on the imputation accuracy and to suggest the appropriate number of reference population sets for the imputation in Hanwoo cattle. A total of 3,821 Hanwoo cattle were divided into reference and validation populations. The reference sets consisted of 50k (38,916) marker data and different population sizes (500, 1,000, 1,500, 2,000, and 3,600). The validation sets consisted of four validation sets (Total 889) and the different marker density (5k [5,000], 10k [10,000], and 15k [15,000]). The accuracy of imputation was calculated by direct comparison of the true genotype and the imputed genotype. In conclusion, when the lowest marker density (5k) was used in the validation set, according to the reference population size, the imputation accuracy was 0.793 to 0.929. On the other hand, when the highest marker density (15k), according to the reference population size, the imputation accuracy was 0.904 to 0.967. Moreover, the reference population size should be more than 1,000 to obtain at least 88% imputation accuracy in Hanwoo cattle.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.3
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• pp.209-220
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• 2022

Objectives: This study was performed to suggest how to re-establish criterion for toxic substances under the Chemical Control Act (CCA) in South Korea by comparing the GHS (Globally Harmonized System of Classification and Labeling of Chemicals) score and toxic properties. Methods: Toxic substances were classified into seven groups (Acute toxicity (1A), Chronic toxicity (2C), Environmental hazards (3E), Acute toxicity & chronic toxicity (4AC), Chronic toxicity & environmental hazards (5CE), Acute toxicity & environmental hazards (6AE), and Acute toxicity & chronic toxicity & environmental hazards (7ACE)) according to their toxic properties. The GHS score was calculated to sum up five toxicity indicators (health acute toxicity, health repeated toxicity, carcinogenicity, health other chronic toxicity and environmental hazards). Results: The GHS score of 7ACE was higher by 7 times that of 1A. 1A is the only group which has lower than the total GHS score. The highest score was 47, for sodium chromate (CAS no. 7775-11-3), which belongs to group 7ACE. This is classified as acute toxicity, carcinogenicity, germ cell mutagenicity, reproductive toxicity, and acute and chronic environmental hazard. On the other hand, the lowest score was 2.75, which was assigned to 177 chemicals belonging to group 1A. When the health acute toxicity indicator was omitted from the toxic criterion, toxic substances could be divided into the sub-groups 'human chronic hazards group' (HCG) and 'environmental hazards group' (EG) according to their GHS score and properties. Conclusions: The proposed criterion for toxic substances is to establish sub-groups defined as HCG and EG for separate control and that the 1A group be moved to substances requiring preparation for accidents under the CCA.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3440-3447
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• 2022

The accuracy of the photoatomic cross-section data is of great importance in the field of radiation protection, particularly in the characterization of radiation shielding materials. With the release of the latest and probably the most accurate photoatomic data library, EPDL2017, the need to re-evaluate all the existing and already established mass attenuation coefficients (MACs) of all radiation shielding materials arises. The MACs of several polymers, alloy-based, glasses, and building materials used in a nuclear medicine facility were investigated using the EPDL2017 library embedded in EpiXS software and were compared to MACs available in the literature. The relative differences between MAC_EpiXS and MACXCOM were negligible, ranging from 0.02% to 0.36% for most materials. However, for material like a glass comprising of elements Te and La evaluated near their corresponding K-edge energies, the relative differences in MACs increased up to 1.46%. On the other hand, a comparison with MACs calculated based on EPDL97 (a predecessor of EPDL2017) revealed as much as a 6.61% difference. Also, it would seem that the changes in MACs were more evident in the materials composed of high atomic number elements evaluated at x-ray energies compared to materials composed of low atomic number elements evaluated at gamma-ray energies.

• Nutrition Research and Practice
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• v.15 no.4
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• pp.516-527
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• 2021

BACKGROUND/OBJECTIVES: This study examined the association of depressive symptoms, stress perception, and suicidal ideation with overall dietary quality using the newly developed Korean healthy eating index (KHEI). SUBJECTS/METHODS: This study included 9,607 adults (3,939 men and 5,668 women, ≥ 19 years) who participated in the 6th Korea National Health and Nutrition Examination Survey 2013 and 2015. The KHEI scores were calculated using the food frequency questionnaire data. Survey logistic regression analyses were performed to analyze the association between psychiatric distress and dietary quality. RESULTS: The percentage of subjects with experience of depressive mood, higher stress perception, and suicidal ideation was 8.2%, 25.0%, and 3.7% in men and 15.4%, 27.3%, and 6.0% in women, respectively. The mean KHEI score was 61.5 ± 0.29 in men and 64.8 ± 0.24 in women (P < 0.001). The present study found a difference in the adherence to specific dietary components of the KHEI between sexes. Men experiencing depressive symptoms were less likely to eat meat, fish, eggs, and beans, while depressed women showed lower vegetable intake. Both men and women with suicidal ideation showed a lower intake of vegetables. The men with stress had a lower breakfast eating score than those without stress (7.21 vs. 6.77, P = 0.016). The multivariate-adjusted odds ratios for depressive symptoms, stress perception, and the suicidal idea in women with the highest quartile of KHEI scores compared to the lowest quartile was 0.69 (95% confidence interval, 0.51-0.92), 0.73 (0.58-0.82), and 0.52 (0.33-0.82), respectively and significant dose-response associations were observed (P for trends < 0.05 for all). On the other hand, these associations were not observed in men after adjusting for the confounding variables (P for trends > 0.05 for all). CONCLUSIONS: Poor adherence to dietary recommendations is associated with psychological distress, especially in women.

• Journal of Conservation Science
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• v.37 no.6
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• pp.659-669
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• 2021

In this study, vegetation index, the vegetation index calculated based on hyperspectral images was used to monitor Petroglyphs of Cheonjeon-ri, Ulju from 2014 to 2020. To select suitable the vegetation index for monitoring, indoor analysis was performed, and considering the sensitivity to biocontamination, Normalized Difference Vegetation Index (NDVI) and Triangular Vegetation Index (TVI) were selected. As a result of monitoring using the selected vegetation index, NDVI increased from 2014 to 2018 and then decreased in 2020, after preservation treatment. On the other hand, TVI was difficult to confirm the tendency during the monitoring. This difference was due to the variation in spectral reflectance according to the photographing conditions by year. Therefore NDVI is less sensitive to spectral reflectance deviation than TVI, so it can be used for monitoring. In order for TVI to be used, however, in-depth study is needed.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.103-110
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• 2022

Ultrafine Particle number and size distributions were simultaneously measured at rural area around the power plant in Dangjin, South Korea. New Particle formation and growth events were frequently observed during January, 2021 and classified based on their strength and persistence as well as the variation in geometric mean diameter(GMD) on January 12, 21 and 17. In this study, we investigated mechanisms of new particle growth based on measurements using a high resolution time of flight aerosol mass spectrometer(HR-ToF-AMS) and a scanning mobility particle sizer(SMPS). On Event days(Jan 12 and 21), the total average growth rate was found to be 8.46 nm/h~24.76 nm/hr. These growth rate are comparable to those reported for other urban and rural sites in South Korea using different method. Comparing to the Non-Event day(Jan 17), New Particle Growth mostly occurred when solar radiation is peaked and relative humidity is low in daytime, moreover enhanced under the condition of higher precusors, NO₂ (39.9 vs 6.2ppb), VOCs(129.5 vs 84.6ppb), NH₃(11 vs 4.7ppb). The HR-ToF-AMS PM_1.0 composition shows Organic and Ammoniated nitrate were dominant species effected by emission source in domestic. On the other hand, The Fraction of Ammoniated sulfate was calculated to be approximately 16% and 31% when air quality is inflow from China. Longer term studies are needed to help resolve the relative contributions of each precusor species on new particle growth characteristics.

• Journal of Korean Public Health Nursing
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• v.36 no.3
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• pp.417-430
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• 2022

Purpose: The purpose of this study was to develop a respiratory infection prevention program for the rural elderly in the post-coronavirus disease 2019 (COVID-19) era. Methods: The Delphi method was used to validate the contents of the program. Two rounds of Delphi surveys and one individual interview were conducted on four subjects and 16 categories with nine experts. Content validity was calculated using the content validity ratio (CVR) and coefficient of variation (CV). Results: This study verified the content validity of the existing program components, such as respiratory infection prevention characteristics, cough etiquette, correct hand washing, oral hygiene, correct tooth brushing, and exercise by walking. The study comprised 28 categories covering seven subjects, including the provision of knowledge and information about COVID-19, environmental management for respiratory infection prevention, and exercise training for immunity enhancement. Conclusion: This Delphi study examined the respiratory infection prevention program that was redesigned for the post-COVID-19 era and confirmed the validity of the educational contents. The findings of this study suggest that the program can be used practically for the prevention of respiratory infection among the rural elderly.

• Investigative Magnetic Resonance Imaging
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• v.26 no.2
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• pp.117-124
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• 2022

Purpose: In this study, we provide a way to assess even a slight effect of exercise on trunk-muscle activity. Materials and Methods: Seven healthy male participants (mean age, 24.7 ± 3.2 years; height, 171.2 ± 9.8 cm; and weight, 63.8 ± 11.9 kg) performed 15 sets of an exercise with 20 repetitions of 90° hip and right-knee flexion while lying supine. The exercise intensity was measured using the 10-point Rating of Perceived Exertion Scale after the first and 15th sets of exercises. Although cross-sectional areas and functional T2 mapping using ultrafast imaging (fast-acquired muscle functional magnetic resonance imaging, fast-mfMRI) have been proposed for imaging to evaluate exercise-induced muscle activity in real time, no previous studies have reported on the evaluation of trunk-muscle activity using functional T2 mapping. As a method for assessing trunk-muscle activity, we compared functional T2 mapping using ultrafast imaging (fast-mfMRI) with cross-sectional areas. Results: Although the muscle cross-sectional areas were increased by the exercise, there was no significant difference at rest. On the other hand, for all sets, the changes in T2 were significant compared with those at rest (P < 0.01). These results demonstrate that T2, calculated from fast-mfMRI images can be used to detect even a small amount of muscle activity induced by acute exercise, which was impossible to do with cross-sectional areas. Conclusion: Fast-mfMRI, which can also display functional information with detailed forms, enabled non-invasive real-time imaging for identifying and evaluating the degree of deep trunk-muscle activity induced by exercise.