• The Mathematical Education
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• v.62 no.3
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• pp.363-380
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• 2023

This study analyzed the difficulties and mathematical modeling knowledge improvement that an elementary school teacher experienced in modifying a mathematics textbook task to a mathematical modeling task. To this end, an elementary school teacher with 10 years of experience participated in teacher-researcher community's repeated discussions and modified the average task in the data and pattern domain of the 5th grade. The results are as followings. First, in the process of task modification, the teacher had difficulties in reflecting reality, setting the appropriate cognitive level of mathematical modeling tasks, and presenting detailed tasks according to the mathematical modeling process. Second, through repeated task modifications, the teacher was able to develop realistic tasks considering the mathematical content knowledge and students' cognitive level, set the cognitive level of the task by adjusting the complexity and openness of the task, and present detailed tasks through thought experiments on students' task-solving process, which shows that teachers' mathematical modeling knowledge, including the concept of mathematical modeling and the characteristics of the mathematical modeling task, has improved. The findings of this study suggest that, in terms of the mathematical modeling teacher education, it is necessary to provide teachers with opportunities to improve their mathematical modeling task development competency through textbook task modification rather than direct provision of mathematical modeling tasks, experience mathematical modeling theory and practice together, and participate in teacher-researcher communities.

• Journal of Korean Elementary Science Education
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• v.42 no.1
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• pp.194-209
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• 2023

This study aims to present implications for the appropriate establishment and development of a science-authorized textbook system through an understanding of the process of selecting science-authorized textbooks and analyzing the perception of teachers. Toward this end, this study conducted interviews with five elementary school teachers who participated in the science textbook selection process, surveys on 32 teachers, and analysis on the authors of the textbooks. The result demonstrated, first, that the "opinion gathering" stage was the most important one, and a council was formed in consideration of career and major. Moreover, the evaluation standard was reorganized and used according to the situation of the school. Second, in the process of opinion gathering, the teachers used a method for reviewing the entire textbook for each teacher. Inquiry activities and textbook composition (readability) were crucially considered as internal factors, and teaching and learning materials, such as videos, were deemed extremely important as external factors. The variable of the author, which is an indicator of the reliability and expertise of textbooks, was also recognized as vital. Third, the deliberation by the School Committee and the report by the principal were recognized as the administrative final step after selection. Finally, selecting the most suitable textbooks for each grade group was recognized as more important than arbitrarily unifying textbooks for the third and fourth grades and for the fifth and sixth grades.

• Journal of Veterinary Clinics
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• v.40 no.2
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• pp.130-134
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• 2023

A 12-year-old Standard Poodle presented with intermittent weakness and occasional dyspnea at the Veterinary Medicine Teaching Hospital of Kangwon National University. A grade of 4 out of 6 systolic murmur with an irregular tachycardic rhythm was auscultated on both sides of the chest. Systolic blood pressure was 140 mmHg. Panting was noticed in the hospital, but there was no crackle sound. Blood analysis revealed mild increases in liver panel levels (alanine aminotransferase 149 [reference interval, 19-70] U/L; and alkaline phosphatase, 185 [reference interval, 15-127] U/L) and severe increases in cardiac biomarker levels (n-terminal pro-brain natriuretic peptide, 4169 [reference interval, 50-900] pmol/L; and cardiac troponin I, 0.22 [reference interval, 0.03-0.12] ng/mL). On electrocardiography, irregularly irregular supraventricular tachycardic rhythm with an f-wave and no distinct p-wave was observed. Generalized cardiomegaly with an enlarged right atrium and left ventricle was confirmed on thoracic radiography. Moreover, hepatomegaly and an enlarged caudal vena cava were observed. Echocardiographic evaluation revealed a fibromuscular diaphragm in the right ventricle. Because of the obstructive lesion in the right ventricle, the right atrium and ventricle were enlarged (right atrial area index, 38.82 cm²/m² [reference interval, 4.2-10.2 cm²/m²]; right ventricle end-diastolic area index, 14.152 cm²/m² [reference interval, 4.9-10.92 cm²/m²]). Accordingly, the patient was diagnosed with double-chambered right ventricle (DCRV). Pimobendan, furosemide, enalapril, diltiazem, and S-adenosylmethionine (SAMe) were prescribed, and all symptoms were relieved. DCRV is a right-sided congenital heart defect resembling pulmonic valve stenosis. If symptoms are not severe, medical therapy can be facilitated without surgery or the balloon dilation.

• Steel and Composite Structures
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• v.47 no.1
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• pp.91-102
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• 2023

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train sub-model was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h - 350 km/h train running speed, the limit values of grade I, II, and III of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

• Journal of The Korean Association For Science Education
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• v.43 no.2
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• pp.59-72
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• 2023

This study analyzed a group interview with six earth science teachers and eight middle school students to find out the evaluations and criteria they use to evaluate VR/AR contents (two virtual reality content and two augmented reality contents) in middle school science digital textbook. The study found the VR/AR contents were evaluated on four criteria as follows: VR/AR media characteristics; technical operation; user interface; and teaching-learning design. The evaluations can be summarized by each criterion. First, regarding VR/AR media characteristics, interesting features of VR/AR contents were considered relatively advantageous compared to other media like videos. However, its shortage of visual presence and inconvenience of using markers were mentioned as shortcomings. Second, in the technical operation criteria, teachers and students found the following conditions as technically challenging: failing to properly operate on a particular OS; huge volumes of contents in the application; and frequent freezing when using the application. Third, poor intuitiveness and lack of flexibility were found as negative aspects in user interface. Fourth, regarding teaching-learning design, the teachers evaluated whether the VR/AR contents delivered scientifically accurate information; whether they incorporated class goals set by teachers; and whether they can help students' inquiry. It turned out teachers gave negative feedbacks on VR/AR contents. The students evaluated VR/AR contents by assessing whether they help them with learning science but concluded they did not regard them necessary in science learning at school. Based on the findings, this study discusses which development direction VR/AR contents should take to be useful in teaching and learning science.

• Design Convergence Study
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• v.14 no.2
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• pp.1-16
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• 2015

As childhood obesity and nutrition imbalance emerge as social issues in South Korea today, the development of education materials on diets and nutrition has become important and has been attempted in diverse ways. The present study was conducted on early elementary school students with the objective of establishing directions for the design of personalized nutrition education materials that can promote a proper, balanced diet for children through application in daily life of knowledge acquired from self-learning linked to nutrition education that is taking place in their schools. For this purpose, a review of previous theoretical literature on nutrition education for early elementary students was performed. Survey questions were formulated based on the advice of field experts in medicine, education, and design and the survey was conducted among 110 children from 1st and 2nd grade in two elementary schools, one in Seoul and the other in Changwon. The results obtained from the user evaluation suggested that the early elementary school students showed positive reaction to nutrition education, had preference for the type of learning using multimedia-based contents and quiz activities, were willing to learn about calorie-adjusted meals, preferred the Gothic typeface and orange and green colors. Furthermore, they showed positive opinion on the use of numerical surveying method and pictorial style similar to actual appearance in connection with nutrition-related information representation. and preferences regarding learning styles and design elements

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.62-69
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• 2023

The use of low-grade coal is continuously increasing with the development of combustion technology and cost reduction for coal used in thermal power plants . During combustion, the latent heat of evaporation due to moisture is large, and there is a risk of spontaneous combustion and dust explosion during the process of storing and pulverizing coal. This study compared and evaluated the minimum explosive concentration and explosive strength of four types of coal dust-fine, coal dust-coarse, wood pallet+organic dust, and wood chip with coal powder collected from domestic power plant D. The minimum explosive concentration of coal dust was measured according to JIS Z 8818:2002, and the explosion strength was tested according to ASTM E1226 using a Siwek 20 L Chamber Apparatus. As a result of the minimum explosive concentration test, it was found that coal dust-fine has a risk of dust explosion, and since an explosion occurs at a dust concentration of 130 g/m³ of wood chips, it was found that there is a risk of explosion at the lowest dust concentration. According to the dust explosion class standard, Kst is less than 200 bar m/s, and all samples fall under the explosion class St 1, and the dust has a low risk of explosion.

• Journal of the Korean Chemical Society
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• v.68 no.2
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• pp.93-106
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• 2024

This study investigated differences in presence, immersion, and situational interest in small group learning using augmented reality, based on the degree of tool sharing. 84 eighth-grade students participated in small groups of four. Each group was randomly assigned to one of three environments based on marker and device sharing: the shared environment (shared marker and device usage), the mixed environment (shared marker and individual device usage), and the individual environment (individual marker and device usage). Small group learning using augmented reality was conducted for three class periods, focusing on the "Characteristics of Matter" unit. One-way ANOVA results for the dependent variables revealed that, compared to the shared environment, presence and situational interest were significantly higher in the mixed environment, while immersion and situational interest were significantly higher in the individual environment. MANOVA results for the sub-components of each dependent variable showed significant differences in realness for presence, antecedents and experiences for immersion, and instant enjoyment, novelty, and total interest for situational interest. Analysis of interviews and classroom observations indicated that students in shared and individual environments tended to use their devices individually when utilizing augmented reality. However, in mixed environments, students showed a tendency to use their devices collaboratively, leading to more active interactions. Based on these findings, environments for using tools to enhance the effectiveness of small group learning using augmented reality are discussed.

• Korean Journal of Environment and Ecology
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• v.38 no.1
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• pp.79-89
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• 2024

The purpose of this study was to evaluate the area adjustment criteria and methods of the feasibility study of national park plans by applying them to Hallyeohaesang National Park. As a result of the ecological-based assessment used to identify the adjustment target areas, the ecological-based assessment Grades I and II that can be considered for inclusion were analyzed as 10.0% and 40.4%, respectively. Grade V, which can be considered for release, was 9.9%. As a result of the inclusion and release suitability assessment, the area subject to inclusion was 35.150 km² (3.669 km² on land and 31.481 km² at sea), and the area subject to release was 0.071 km² on land. When local governments and residents request the release of a park area for public interest or convenience, the release can be considered as long as the total area does not change, which is called a mutual exchange. The release area determined by mutual exchange was 10.386 km². It was 146 times the area determined by the suitability assessment for release. Matching the areas released by the mutual exchange with the ecological-based assessment, 70.6% (7.321 km²) was in Grades I and II, which can never be released. As a result, it was determined that the area adjustment of the feasibility study of Hallyeohaesang National Park was based on a very limited application of the results of the ecological-based assessment or the release suitability assessment. Also, mutual exchange was the key to area adjustment of the feasibility studies of national parks.

• Korean Journal of Radiology
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• v.21 no.12
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• pp.1317-1325
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• 2020

Objective: The aim of this study was to prospectively evaluate whether liver stiffness (LS) assessments, obtained by two-dimensional (2D)-shear wave elastography (SWE) with a propagation map, can evaluate liver fibrosis stage using histopathology as the reference standard. Materials and Methods: We prospectively enrolled 123 patients who had undergone percutaneous liver biopsy from two tertiary referral hospitals. All patients underwent 2D-SWE examination prior to biopsy, and LS values (kilopascal [kPa]) were obtained. On histopathologic examination, fibrosis stage (F0-F4) and necroinflammatory activity grade (A0-A4) were assessed. Multivariate linear regression analysis was performed to determine the significant factors affecting the LS value. The diagnostic performance of the LS value for staging fibrosis was assessed using receiver operating characteristic (ROC) analysis, and the optimal cut-off value was determined by the Youden index. Results: Reliable measurements of LS values were obtained in 114 patients (92.7%, 114/123). LS values obtained from 2D-SWE with the propagation map positively correlated with the progression of liver fibrosis reported from histopathology (p < 0.001). According to the multivariate linear regression analysis, fibrosis stage was the only factor significantly associated with LS (p < 0.001). The area under the ROC curve of LS from 2D-SWE with the propagation map was 0.773, 0.865, 0.946, and 0.950 for detecting F ≥ 1, F ≥ 2, F ≥ 3, and F = 4, respectively. The optimal cut-off LS values were 5.4, 7.8, 9.4, and 12.2 kPa for F ≥ 1, F ≥ 2, F ≥ 3, and F = 4, respectively. The corresponding sensitivity and specificity of the LS value for detecting cirrhosis were 90.9% and 88.4%, respectively. Conclusion: The LS value obtained from 2D-SWE with a propagation map provides excellent diagnostic performance in evaluating liver fibrosis stage, determined by histopathology.