• Computers and Concrete
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• v.32 no.3
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• pp.247-261
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• 2023

Due to the non-uniform distribution of meso-structure, the diffusion of chloride ions in concrete show the characteristics of characteristics of randomness and fuzziness, which leads to the non-uniform distribution of chloride ions and the non-uniform corrosion of steel rebar in concrete. This phenomenon is supposed as the main reason causing the uncertainty of the bearing capacity deterioration of reinforced concrete structures. In order to analyze and predict the durability of reinforced concrete structures under chloride environment, the random features of chloride ions transport in concrete were studied in this research from in situ meso-structure of concrete. Based on X-ray CT technology, the spatial distribution of coarse aggregates and pores were recognized and extracted from a cylinder concrete specimen. In considering the influence of ITZ, the in situ mesostructure of concrete specimen was reconstructed to conduct a numerical simulation on the diffusion of chloride ions in concrete, which was verified through electronic microprobe technology. Then a stochastic study was performed to investigate the distribution of chloride ions concentration in space and time. The research indicates that the influence of coarse aggregate on chloride ions diffusion is the synthetic action of tortuosity and ITZ effect. The spatial distribution of coarse aggregates and pores is the main reason leading to the non-uniform distribution of chloride ions both in spatial and time scale. The chloride ions concentration under a certain time and the time under a certain concentration both satisfy the Lognormal distribution, which are accepted by Kolmogorov-Smirnov test and Chi-square test. This research provides an efficient method for obtain mass stochastic data from limited but representative samples, which lays a solid foundation for the investigation on the service properties of reinforced concrete structures.

• Journal of Environmental Impact Assessment
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• v.32 no.4
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• pp.230-241
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• 2023

At a time when it is urgent to establish a management system for landscape quality assessment of offshore wind farms in Korea, we analyzed foreign cases to draw implications for improving the landscape quality assessment of offshore wind farms in Korea and to explore the direction of efficient landscape assessment. The main contents derived from the analysis of overseas cases and systems are as follows. First, offshore wind farms are large-scale projects, and it is necessary to consider the landscape from the pre-planning stage, as in overseas cases. Second, the evaluation items for marine landscape quality should be expanded and systematized. Third, a flexible evaluation system that can consider new landscape impacts is required. In order to identify the landscape impacts of offshore wind farm projects, we refer to the landscape assessment items and procedures derived from overseas cases, but reflect them appropriately to the domestic maritime conditions, and specifically introduce a plan to minimize the landscape impacts that may occur during offshore wind farm projects to contribute to the sustainable use of offshore wind power.

• Smart Media Journal
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• v.11 no.11
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• pp.49-62
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• 2022

Recently, with the development of Smart City Solutions such as Big data, AI, IoT, Autonomous driving, and Digital twins around the world, the proliferation of various smart devices and social media, and the record of the deeds that people have left everywhere, the construction of Smart Cities using the "Big Data" environment in which so much information and data is produced that it is impossible to gauge the scale is actively underway. The Purpose of this study is to construct an objective and systematic analysis Model based on Big Data to improve the transportation convenience of citizens and formulate efficient policies in Urban Information and Public Transportation accessibility in sustainable Smart Cities following the 4th Industrial Revolution. It is also to derive the methodology of developing a Big Data-Based public transport accessibility and policy management Platform using a sustainable Urban Public DB and a Private DB. To this end, Detailed Living Areas made a division and the accessibility of basic living amenities of Gwangju Metropolitan City, and the Public Transportation system based on Big Data were analyzed. As a result, it was Proposed to construct a Big Data-based Urban Information and Public Transportation accessibility Platform, such as 1) Using Big Data for public transportation network evaluation, 2) Supporting Transportation means/service decision-making based on Big Data, 3) Providing urban traffic network monitoring services, and 4) Analyzing parking demand sources and providing improvement measures.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.99-111
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• 2022

Vegetation is the basis for biodiversity conservation and sustainable development. In the Environmental Impact Assessment (EIA), which is the most direct and efficient policy measure to prevent degradation of nature, vegetation-related assessment has limitations as it is not based on quantitative and scientific methods. In addition, it focuses on the presence of protected species; hence, it does not take into account the role of vegetation as a habitat on a wide-area scale. As a way to overcome these limitations, this study aims to contribute to the quantification and advancement of future EIA on vegetation. Through the review of previous studies, core areas, connectivity, and vegetation condition were derived as the items to be dealt within the macroscopic aspect of vegetation impact assessment. Each item was spatially constructed using land cover maps and satellite imageries, and time series change analysis was performed. As a result, it was found that vegetation has been continuously deteriorating due to development in all aspects, and in particular, development adversely affects not only the inside of the project site but also the surrounding area. Although this study suggested the direction for improvement of the EIA in the vegetation sector based on data analysis, a more specific methodology needs to be established in order to apply it to the actual EIA process. By actively utilizing various environmental spatial data, the impact of the development on the natural ecosystem can be minimized.

• Journal of The Korean Association For Science Education
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• v.43 no.3
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• pp.277-294
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• 2023

Science education researchers have discussed more effective STPD(Science Teacher Professional Development) based on a variety of perspectives, pointing out the limitations of traditional STPD. In this study, we selected eight major issues for more efficient STPD based on the literature review, summarized the literature review contents for each issue, and proposed a draft STPD standard based on the literature review. Using the draft STPD standard, a questionnaire for the Delphi survey was developed and a two-phase Delphi survey was conducted. The questionnaire consisted of 25 statements describing the STPD standard, and respondents were asked to indicate the validity and importance of the statement on a Likert scale, followed by an explanation and suggestions for revision. Twenty-one science educators and science teachers participated in the Delphi survey, and the results of the second round of the survey showed high levels of agreement on the validity and importance of all statements describing the STPD standard. For the content validity ratio and coefficient of variation, all statements met the criteria, and for the convergence and consensus, all but two statements met the criteria. Two statements were revised to reflect comments from the Delphi survey and were included in the final STPD standard. As a result, we developed STPD standard consisting of 23 statements in eight categories, and we discussed the disadvantages and advantages of the developed STPD standard and how to utilize them, as well as suggestions for future improvement and research.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.285-303
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• 2023

Interest in building underground spaces is increasing for the creation of downtown infrastructure and efficient space utilization. A representative method of utilizing underground space is a tunnel, and in addition to road tunnels, the construction of utility tunnels such as power conduits and utility conduits is gradually increasing. The current basic tunnel construction method can be divided into NATM (New Austrian Tunnelling Method) and TBM (Tunnel Boring Machine). The NATM is a reliable method, but it is accompanied by vibration and noise due to blasting. In the case of the TBM excavation method, there are disadvantages in terms of construction period and construction cost, but it is possible to improve economic feasibility by introducing appropriate complementary methods. In this study, a blasting method was develop using the NATM after TBM pre-excavation using the protective shield method. This is a method that compensates for the disadvantages of each tunnel construction method, and is expected to reduce construction costs, blasting vibration, and noise. In order to review the performance of the developed method, an experiment was conducted to evaluate the performance of explosion-proof tube to which a protective shield scale model was applied, and the impact of blasting vibration of the protective shield method was analyzed.

• 한국노년학
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• v.31 no.3
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• pp.607-621
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• 2011

Purpose The purpose of this study was to examine the relationship between physical activities, sleep disturbance, and health related quality of life (HRQOL) in patients with chronic obstructive pulmonary disease (COPD). Methods A descriptive survey design used pretest dataset of COPD symptom management intervention study (N=245). Measures included the international physical activity questionnaire, the COPD and asthma sleep impact scale, and the St. George's respiratory questionnaire of HRQOL. The data were analyzed using descriptive analysis, t-test, ANOVA, Pearson correlation coefficients, and simultaneous multiple regression by the SPSS WIN 18.0 program. Results The mean scores (SD) of HRQOL and sleep disturbance were 36.04 (19.43) and 14.33 (6.20), respectively. About 32% of participants were physically inactive. The multivariate approach showed the patients who have more sleep disturbance (β=.27), lower levels of FEV1 % predicted (β=-.23), lower physical activities (β=-.19), lower household income (β=-.16), and diagnosed longer than 5 years (β=.14) reported lower HRQOL (R²=.34). Conclusion The findings of this study suggest that improving the quality of sleep and physical activities can be efficient strategies for HRQOL in patients with COPD. Future research in enhancing HRQOL through improving sleep quality and physical activities is needed.

• The Journal of the Korea Contents Association
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• v.22 no.8
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• pp.377-391
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• 2022

The objective of this study is to understand the operational status of the support projects for childcare in daycare centers operated by the Support Centers for Childcare(SCC) during the COVID-19 pandemic and find ways to improve and develop the project operation. To this end, data were collected and analyzed through in-depth interviews from the 1st week to the 4th week of February 2022 with six childcare agents in charge of the support projects for childcare in daycare centers in the SCC located in Seoul and Gyeonggi Province. As a result of the study, it was found that the demand for diversification of project operation methods, expansion of non-face-to-face education, individual consulting, and small-scale education increased while operating the support projects for childcare in daycare centers in the SCC during the COVID-19 pandemic. Operational difficulties were found to be a lack of ability to use media, the burden of coping with unpredictable situations, and insufficient communication between daycare centers and childcare policy institutions. As for the support needs, it was found that it is necessary to employ computer specialists, establish an environment for activating online education, and provide an efficient work delivery system in emergencies.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.77-83
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• 2023

Energy consumption is increased by rapid industrialization. As a result, climate change is accelerating due to the increase in CO₂ concentration in the atmosphere. Therefore, a shift in the energy paradigm is required. Hydrogen is in the spotlight as a part of that. Currently 95% of hydrogen is fossil fuel-based reforming hydrogen which is accompanied by CO₂ emissions. This is called gray hydrogen, if the CO₂ is captured and emission of CO₂ is reduced, it can be converted into blue hydrogen. There are 3 technologies to capture CO₂: absorption, adsorption and membrane technology. In order to select CO₂ capture technology, the analysis of the exhaust gas should be carried out. The concentration of CO₂ in the flue gas from the hydrogen production process is higher than 20%if water is removed as well as the emission scale is classified as small and medium. So, the application of the membrane technology is more advantageous than the absorption. In addition, if LNG cold energy can be used for low temperature CO₂ capture system, the CO₂/N₂ selectivity of the membrane is higher than room temperature CO₂ capture and enabling an efficient CO₂ capture process. In this study, we will analyze the flue gas from hydrogen production process and discuss suitable CO₂ capture technology for it.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1371-1388
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• 2023

Floods are becoming more severe and frequent due to global warming-induced climate change. Water disasters are rising in Korea due to severe rainfall and wet seasons. This makes preventive climate change measures and efficient water catastrophe responses crucial, and synthetic aperture radar satellite imagery can help. This research created 1,423 water body learning datasets for individual water body regions along the Han and Nakdong waterways to reflect domestic water body properties discovered by Sentinel-1 satellite radar imagery. We created a document with exact data annotation criteria for many situations. After the dataset was processed, U-Net, a deep learning model, analyzed water body detection results. The results from applying the learned model to water body locations not involved in the learning process were studied to validate soil water body monitoring on a national scale. The analysis showed that the created water body area detected water bodies accurately (F1-Score: 0.987, Intersection over Union [IoU]: 0.955). Other domestic water body regions not used for training and evaluation showed similar accuracy (F1-Score: 0.941, IoU: 0.89). Both outcomes showed that the computer accurately spotted water bodies in most areas, however tiny streams and gloomy areas had problems. This work should improve water resource change and disaster damage surveillance. Future studies will likely include more water body attribute datasets. Such databases could help manage and monitor water bodies nationwide and shed light on misclassified regions.