• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.167-174
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• 2021

Recent investigation into the integrity of nuclear containment buildings has highlighted the importance of developing an elaborate diagnostic method to evaluate the distribution and size of cavities inside concrete walls. As part of developing such a method, this paper presents a finite element approach to modeling elastic waves propagating in the containment building walls of a nuclear power plant. We introduce a perfectly matched layer (PML) wave-absorbing boundary to limit the large-scale nuclear containment wall to the region of interest. The formulation results in a semi-discrete form with symmetric damping and stiffness matrices. The transient elastic wave equations for a mixed unsplit-field PML were solved for displacement and stresses in the time domain. Numerical results show that the sensitivity of displacement, velocity, acceleration, and stresses is large depending on the size and location of the cavity. The dynamic response of the wall slightly differs depending on the existence of the containment liner plate. The results of this study can be applied to a full-waveform inversion approach for characterizing cavities inside a containment wall.

• Convergence Security Journal
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• v.20 no.4
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• pp.27-34
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• 2020

Recently, the fourth industrial revolution technology has not only changed everyday life greatly through technological development, but has also become a major keyword in the establishment of defense policy. In particular, Internet of Things, cloud, big data, mobile and cybersecurity technologies, called ICBMS, were selected as core leading technologies in defense information policy along with artificial intelligence. Amid the growing importance of the fourth industrial revolution technology, research is being carried out to develop the C4I system, which is currently operated separately by the Joint Chiefs of Staff and each military, including the KJCCS, ATCIS, KNCCS and AFCCS, into an integrated system in preparation for future warfare. This is to solve the problem of reduced interoperability for joint operations, such as information exchange, by operating the C4I system for each domain. In addition, systems such as the establishment of an integrated C4I system and the U.S. military's Risk Management Framework (RMF) are essential for efficient control and safe operation of weapons systems as they are being developed into super-connected and super-intelligent systems. Therefore, in this paper, the intelligent cyber threat detection, management of users' access to information, and intelligent management and visualization of cyber threat are presented in the future C4I system based on big data/cloud.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.184-192
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• 2022

Valve internal leakage is caused by damage to the internal parts of the valve, resulting in accidents and shutdowns of the piping system. This study investigated the possibility of a real-time leak detection method using the acoustic emission (AE) signal generated from the piping system during the internal leakage of a butterfly valve. Datasets of raw time-domain AE signals were collected and postprocessed for each operation mode of the valve in a systematic manner to develop a data-driven model for the detection and classification of internal leakage, by applying machine learning algorithms. The aim of this study was to determine whether it is possible to treat leak detection as a classification problem by applying two classification algorithms: support vector machine (SVM) and convolutional neural network (CNN). The results showed different performances for the algorithms and datasets used. The SVM-based binary classification models, based on feature extraction of data, achieved an overall accuracy of 83% to 90%, while in the case of a multiple classification model, the accuracy was reduced to 66%. By contrast, the CNN-based classification model achieved an accuracy of 99.85%, which is superior to those of any other models based on the SVM algorithm. The results revealed that the SVM classification model requires effective feature extraction of the AE signals to improve the accuracy of multi-class classification. Moreover, the CNN-based classification can be a promising approach to detect both leakage and valve opening as long as the performance of the processor does not degrade.

• 한국노년학
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• v.40 no.2
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• pp.269-289
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• 2020

The purpose of this study was to analyze the policy and programs of the Seoul50Plus Foundation and to propose policies and programs to promote active aging of middle-aged and elderly people. A single case study was utilized as a research method. The analysis framework of case was approached with four frameworks: the context of policy and program, ideology-goal analysis of policy and program, supplier and customer analysis of policy and program, and process and domain analysis of policy and program. The analysis data included the homepage content of the Seoul50Plus Foundation, related 50+ policy and program data, active aging research papers at home and abroad, and presentation and meeting materials. The results of the research showed that the policy and program background and environment were essential elements for responding to environmental changes in the aging society. In terms of the philosophy-goal, job creation, social participation, and approach to life design were systematically carried out for the ideology of 'creating a new life vision' and promoting active aging. In terms of subject-target, the subject of policy implementation is systematically composed of three stages: 50+ foundation, 50+ campus, and 50+ center. The target was limited to 50+ generations(age 50~64) and had a problem that is limited to applicants. In the process-area analysis, programs such as educational support, work and entrepreneurship support, counseling information, and new-age cultural creation activities were designed to increase added value according to the characteristics of the middle-aged people. In conclusion, the future Seoul50Plus Foundation's policy and lifelong learning programs need to be systematically promoted through cooperation with businesses and universities, expanding the target audience, matching the characteristics of the middle-aged and elderly, and linkage among programs.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.10
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• pp.409-418
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• 2022

In this paper, we propose SAAnnot-C3Pap, a semi-automatic annotation method for obtaining ground truth of a player's posture. In order to obtain ground truth about the two-dimensional joint position in the existing music domain, openpose, a two-dimensional posture estimation method, was used or manually labeled. However, automatic annotation methods such as the existing openpose have the disadvantages of showing inaccurate results even though they are fast. Therefore, this paper proposes SAAnnot-C3Pap, a semi-automated annotation method that is a compromise between the two. The proposed approach consists of three main steps: extracting postures using openpose, correcting the parts with errors among the extracted parts using supervisely, and then analyzing the results of openpose and supervisely. Perform the synchronization process. Through the proposed method, it was possible to correct the incorrect 2D joint position detection result that occurred in the openpose, solve the problem of detecting two or more people, and obtain the ground truth in the playing posture. In the experiment, we compare and analyze the results of the semi-automated annotation method openpose and the SAAnnot-C3Pap proposed in this paper. As a result of comparison, the proposed method showed improvement of posture information incorrectly collected through openpose.

• Journal of The Korean Association For Science Education
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• v.42 no.6
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• pp.611-619
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• 2022

The purpose of this study is to explore the possibility of applying big data analysis to provide appropriate feedback to students using evaluation data in science education at a time when interest in educational data mining has recently increased in education. In this study, we use the evaluation data of 2,576 students who took 24 questions of the national assessment of educational achievement. And we use K-means cluster analysis as a method of unsupervised machine learning for clustering. As a result of clustering, students were divided into six clusters. The middle-ranking students are divided into various clusters when compared to upper or lower ranks. According to the results of the cluster analysis, the most important factor influencing clusterization is academic achievement, and each cluster shows different characteristics in terms of content domains, subject competencies, and affective characteristics. Learning motivation is important among the affective domains in the lower-ranking achievement cluster, and scientific inquiry and problem-solving competency, as well as scientific communication competency have a major influence in terms of subject competencies. In the content domain, achievement of motion and energy and matter are important factors to distinguish the characteristics of the cluster. As a result, we can provide students with customized feedback for learning based on the characteristics of each cluster. We discuss implications of these results for science education, such as the possibility of using this study results, balanced learning by content domains, enhancement of subject competency, and improvement of scientific attitude.

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.471-482
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• 2022

This study aims to investigate the characteristics of wave generation in a deep ocean engineering basin and to develop a meta-model of the transfer function of the wavemaker that reflects the geometric characteristics of the deep ocean engineering basin. To this end, the two-dimensional frequency domain boundary element method was applied to achieve an efficient analysis that reflects the geometric characteristics of the deep ocean engineering basin. The developed numerical method was validated through comparison with the analytical solution. Numerical analyses were conducted for the boundary value problem of the wavemaker according to various periods and the positions of the movable bottom. The numerical results were used to investigate the effect of the geometric characteristics of the deep ocean engineering basin on the transfer function of the wavemaker, and the effect of depth on wave generation was checked by changing the position of the movable bottom. To efficiently utilize the various results of the boundary element method, a meta-model, an approximate model of the transfer function of the wave maker, was developed using a thin plate spline interpolation model. The validity of the developed meta-model was confirmed through a comparison of the results of the model tests.

• Journal of Korean Elementary Science Education
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• v.41 no.2
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• pp.186-198
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• 2022

With the science curriculum about to be revised in 2022, this study aimed to guide curriculum revision by addressing suggested approaches to the electromagnetism education in elementary school science curriculum. The core concepts of electromagnetism are "electric field" and "magnetic field" as a medium of force, but the current curriculum does not properly describe the core concepts of electromagnetism. Mechanics and electromagnetism should be linked in elementary schools to form science curriculum based on core concepts to solve this problem. Additionally, the nine aspects of technology extracted in this study offer various educational contexts to match the development of engineering technology based on electromagnetism. However, the current curriculum does not comprise these various contexts and focuses on the limited content of electric circuits using light bulbs. Therefore, it is necessary to expand the scope of the curriculum to better mirror real-life technology. Through the use of more diverse materials and contexts, the scope and level of STS education as well as conceptual learning could be expanded. Finally, in the case of electric circuit learning, various issues such as difficulty in connecting electric circuits and electric field concepts, representativeness of electric circuit, students' learning difficulty, and phenomena-oriented learning should be considered.

• Journal of Korean Elementary Science Education
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• v.41 no.3
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• pp.501-520
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• 2022

Considering the importance of spatial thinking in the process of learning astronomy, it is necessary to educate pre-service teachers on teaching methods that consider spatial thinking from the teacher training program stage. Accordingly, after providing education on spatial thinking to pre-service science teachers, problems and improvement plans perceived by them were explored for the images and inquiry activities of astronomy textbook units. In this study, spatial thinking in the astronomical domain was defined as the amalgam of the concepts of space, representation tools, and reasoning processes. The juniors attending the University of Education in the metropolitan area were educated on spatial thinking for two weeks in October 2021. They were then asked to voluntarily select one of the astronomy units to analyze problems in the textbooks and present modification plans to address those problems. Finally, 33 cases presented by 22 pre-service science teachers were analyzed, and the results of the study were as follows. Pre-service teachers recognized the problems in textbooks in terms of the concepts of space and reasoning processes, and proposed improvement plans to supplement them. However, in some cases, even if pre-service teachers properly recognized a problem, the improvement plan was not appropriate, or they were not able to analyze the images or inquiry activities in terms of spatial thinking. This study is significant in that it shows that pre-service teachers have the potential to properly reorganize and revise textbooks by participating in teacher training programs on spatial thinking. Furthermore, based on the results of this study, the direction of the teacher training program concerning spatial thinking was discussed.

• Journal of Korean Society of Rural Planning
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• v.29 no.3
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• pp.25-37
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• 2023

According to the 「Rural Spatial Reconstruction and Regeneration Support Act」, enacted on March 29, 2024, all local governments are required to establish a 'Rural Spatial Reconstruction and Regeneration Plan' (hereinafter referred to as the 'Rural Spatial Plan'). In order for the 'Rural Spatial Plan' to be appropriately established, this study analyzed the supply and demand of spatial data from the perspective of user stakeholders and derived implications for improving rural spatial planning data utilization. In conclusion, three key recommendations come from this result. Firstly, it is necessary to establish an integrated DB for rural spatial planning data. This can solve the problem of low awareness of scattered data-providing websites, reduce the processing time of non-GIS data, and reduce the time required to acquire data by securing the availability of data search and download. In particular, research should be conducted on the establishment of a spatial analysis simulation system to support stakeholders' decision-making, considering that many stakeholders have difficulty in spatial analysis because spatial analysis techniques were not actively used in rural projects before the implementation of the rural agreement system in 2020. Secondly, research on how to improve data acquisition should be conducted in each data sector. The data sector group with the lowest ease of receiving are 'Local Community Domain', 'Changes in Domestic and International Conditions', and 'Provision and Utilization of Daily Life Services'. Lastly, in-depth research is needed on how to raise each rural spatial planning data supply stakeholder to the position of player. Stakeholders of 'University Institutions' and 'Public Enterprises and Research Institutes' should give those who participate in the formulation of rural spatial plans access to the raw data collected for public work. Stakeholders of 'Private company' need to come up with realistic measures to build a data pool centered on consultative bodies between existing private companies and then prepare a step-by-step strategy to fully open it by participating various stakeholders. In order to induce 'Village Residents and Associations' stakeholders to play a leading role as owners and producers of data, personnel should be trained to collect and record data related to the village. In addition, support measures should be prepared to continue these activities.