• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.955-967
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• 2022

Existing particle tracking models predict vertical displacement of particles based on the terminal settling velocity in the stagnant water. However, experimental results of the present study confirmed that the settling velocity of particles is influenced by the turbulence effects in turbulent flow, consistent with the previous studies. The settling velocity of particles and turbulent characteristics were measured by using PTV and PIV methods, respectively, in order to establish relationship between the particle settling velocity and the ambient turbulence. It was observed that the settling velocity increase rate starts to grow when the particle diameter is of the same order as Kolmogorov length scale. Compared with the previous studies, the present study shows that the graphs of the settling velocity increase rate according to the Stokes number have concave shapes for each particle density. In conclusion, since the settling velocity in the natural flow is faster than in the stagnant water, the existing particle tracking model may estimate a relatively long time for particles to reach the river bed. Therefore, the results of the present study can help improve the performance of particle tracking models.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.4
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• pp.215-226
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• 2022

Significant efforts have been devoted to developing high-performance composite materials by emulating the structure of biological creatures with superior mechanical characteristics. Nacre has been one of the most sought-after natural structures due to its exceptional fracture toughness compared with the constituent materials. However, the effect of manipulating the nacre-like geometry on the impact performance has not been fully investigated thus far. In this study, composites of randomly manipulated nacreous geometry are numerically developed and the impact performance is analyzed. We develop an algorithm by which the planar area of platelets in the nacre-like design is randomly resized. Thereafter, the numerical models of nonuniform nacre-patterned multi-layer structures are developed and the drop-weight impact simulation is performed. The impact behaviors of the model are evaluated by using the ratio of absorbed energy, the von Mises stress distribution, and the impact force-time curve. Therefore, the effect of the geometric irregularity on the nacre-patterned design is elucidated. This insight can be efficiently utilized in establishing the optimum design of the nacre-patterned structure.

• Korean Journal of Construction Engineering and Management
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• v.23 no.3
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• pp.45-55
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• 2022

BIM models allow building spaces to be instantiated and recognized as unique objects independently of model elements. These instantiated spaces provide the required semantics that can be leveraged for building code checking, energy analysis, and evacuation route analysis. However, theses spaces or rooms need to be designated manually, which in practice, lead to errors and omissions. Thus, most BIM models today does not guarantee the semantic integrity of space designations, limiting their potential applicability. Recent studies have explored ways to automate space allocation in BIM models using artificial intelligence algorithms, but they are limited in their scope and relatively low classification accuracy. This study explored the use of Graph Convolutional Networks, an algorithm exclusively tailored for graph data structures. The goal was to utilize not only geometry information but also the semantic relational data between spaces and elements in the BIM model. Results of the study confirmed that the accuracy was improved by about 8% compared to algorithms that only used geometric distinctions of the individual spaces.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.483-488
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• 2022

In this paper, when a gain grating and a refractive index grating exist simultaneously in a DFB laser diode having a wavelength of 1.55 ㎛, an anti-reflection coating is applied to the right mirror surface so that ρ_r=0. In case of δL<0, the characteristics of the oscillation frequency and oscillation gain have been analyzed. Whenever the phase of the grating on the left side of the mirror continuously decreases by π/2, the δL value of each oscillation mode decreases by about 0.6 to the left of the graph lines of each oscillation mode. The case of the oscillation mode having the lowest threshold gain is the case of κL=10, and in this case, the mode selectivity is relatively low compared to the case of other values of κL. From κL=0.1 to κL=6, the mode selectivity and the frequency stability are excellent. As the mode selectivity is excellent, the frequency stability is excellent. Compared to the case with two cleaved mirrors, the DFB laser diode with anti-reflection coating increases the threshold gain of the oscillation mode by about 2 times, but the mode selectivity becomes about 2 times better.

• Journal of Industrial Convergence
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• v.21 no.1
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• pp.187-192
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• 2023

In this study, trends in ICT education were investigated by analyzing the frequency of appearance of keywords related to machine learning and using conversion of iteration correction(CONCOR) techniques. A total of 304 papers from 2018 to the present published in registered sites were searched on Google Scalar using "ICT education" as the keyword, and 60 papers pertaining to ICT education were selected based on a systematic literature review. Subsequently, keywords were extracted based on the title and summary of the paper. For word frequency and indicator data, 49 keywords with high appearance frequency were extracted by analyzing frequency, via the term frequency-inverse document frequency technique in natural language processing, and words with simultaneous appearance frequency. The relationship degree was verified by analyzing the connection structure and centrality of the connection degree between words, and a cluster composed of words with similarity was derived via CONCOR analysis. First, "education," "research," "result," "utilization," and "analysis" were analyzed as main keywords. Second, by analyzing an N-GRAM network graph with "education" as the keyword, "curriculum" and "utilization" were shown to exhibit the highest correlation level. Third, by conducting a cluster analysis with "education" as the keyword, five groups were formed: "curriculum," "programming," "student," "improvement," and "information." These results indicate that practical research necessary for ICT education can be conducted by analyzing ICT education trends and identifying trends.

• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.439-446
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• 2022

Soybean is a crop with high-quality of protein and oil, and it is one of the most widely used genetically modified (GM) crops in the world today. In South Korea, Kwangan is the most utilized variety as a parental line for GM soybean development. In this study, untargeted LC-MS metabolomic approaches were used to compare metabolite profiles of Kwangan and three other commercial varieties cultivated in Gunwi and Jeonju in 2020 year. Metabolomic studies revealed that the 4 soybean varieties were distinct based on the partial least squares-discriminant analysis (PLS-DA) score plots; 18 metabolites contributed to variety distinction, including phenylalanine, isoflavones, and fatty acids. All varieties were clearly differentiated by location on the PLS-DA score plot, indicating that the growing environment is also attributable to metabolite variability. In particular, isoflavones and linolenic acid levels in Kwangan were significantly lower and higher, respectively compared to those of the three varieties. It was discussed that it might need to include more diverse conventional varieties as comparators in regard to metabolic characteristics of Kwangan for the assessment of substantial equivalence biogenetically engineered soybeans in a Kwangan-variety background.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.532-544
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• 2023

Purpose: To identify and evaluate the risk of chemical fire causative substances by using thermal analysis methods (DSC, TGA) for the hazards and physical property changes that occur when newly used biofuels are mixed with existing fuels It is to use it for identification and evaluation of the cause of fire by securing data related to the method and the hazards of the material according to it. Method: The research method used in this experiment is the differential scanning calorimeter (DSC: Difference in heat flux) through quantitative information on the caloric change from the location, shape, number, and area of peaks. flux) was measured, and the weight change caused by decomposition heat at a specific temperature was continuously measured by performing thermogravimetric analyzer (TGA: Thermo- gravimetric Analyzer). Result: First, in the heat flux graph, the boiling point of the material and the intrinsic characteristic value of the material or the energy required for decomposition can be checked. Second, as the content of biodiesel increased, many peaks were identified. Third, it was confirmed through analysis that substances with low expected boiling points were contained. Conclusion: It was shown that the physical risk of the material can be evaluated by using the risk of biodiesel, which is currently used as a new energy source, through various physical and chemical analysis techniques (DSC + TGA).In addition, it is expected that the comparison of differences between test methods and the accumulation and utilization of know-how on experiments in this study will be helpful in future studies on physical properties of hazardous materials and risk assessment of materials.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.33-44
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• 2023

Wind power is one of the most efficient and reliable energy sources in the transition to a low-carbon society. In particular, offshore wind power provides a high-quality and stable wind resource compared to onshore wind power while both present a higher installed capacity than other renewables. In this paper, we present our new program, the X-WIND program well suitable for the assessment of the substructure of offshore wind turbines. We have developed this program to increase the usability of analysis programs for offshore wind energy substructures by addressing the shortcomings of existing programs. Unlike the existing programs which cannot solely perform the substructure analyses or lack pre-post processors, our X-WIND program can complete the assessment analysis for the offshore wind turbines alone. The X-WIND program is embedded in AutoCAD so that both design and analysis are performed on a single platform. This also performs static and dynamic analysis for wind, wave, and current loads, essential for offshore wind power structures, and includes pre/post processors for designs, mesh developments, graph plotting, and code checking. With this expertise, our program enhances the usability of analysis programs for offshore wind energy substructures, promoting convenience and efficiency.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.2
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• pp.261-275
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• 2023

The purpose of this study was to analyze the conceptual understanding of carbon neutrality among secondary school science pre-service teachers, as well as to identify gaze patterns in visual materials. For this study, gaze tracking data of 20 pre-service secondary school science teachers were analyzed. Through this, the levels of conceptual understanding of carbon neutrality were categorized for the participants, and differences in gaze patterns were analyzed based on the degree of conceptual understanding of carbon neutrality. The research findings are as follows. First, as a result of performing modeling activities to predict carbon emissions and removals until 2100 using the concept of '2050 carbon neutrality,' 50% of the participants held a conception that carbon emissions would continue to increase. Additionally, 25% of the participants did not properly understand the causal relationship between net carbon dioxide emissions and cumulative concentrations. Second, the gaze movements of the participants regarding visual materials related to carbon neutrality were significantly influenced by the information presented in the text area, and in the case of graphs, the focus was mainly on the data area. Moreover, when visual data with the same function and category were arranged, participants showed the most interest in materials explaining concepts or visual data placed on the left side. This implies a preference for specific positions or orders. Participants with lower levels of conceptual understanding and inadequate grasp of causal relationships among elements exhibited notably reduced concentration and overall gaze flow. These findings suggest that conceptual understanding of carbon neutrality including climate change and natural disaster significantly influences interest in and engagement with visual materials.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.691-695
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• 2023

Currently, the utilization of measurement results of the automated measurement system is very low and is at the level of providing only fragmentary measurement results. In this study, we are going to study a structure behavior analysis 3D display system with high precision and reliability for automated measurement data obtained by constructing big data by transmitting massive data values measured in real time to the cloud and using a Python-based algorithm. As a result of the study, as a system that can evaluate the behavior of a structure to a manager in real time, it provides analysis data in real time without significant restrictions regardless of the type of measurement data and sensor, and derived it as a 3D display. In addition, it was analyzed that the manager could grasp the behavior graph of the structure in real time and more easily judge the derivation of the weak part of the structure through data analysis. In the future, by analyzing the behavior of structures in three dimensions using past and present data, it is expected that more effective measurement results can be obtained in terms of repair, reinforcement, and maintenance of realistic structures.