• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.141-147
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• 2019

Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.376-386
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• 2019

The purpose of this study was to explore the learning progression of logical thinking in acid and base chemical reactions and to evaluate its validity. For this purpose, we collected 387 participants in 9 schools of elementary, middle and high schools nationwide. The questionnaire developed in this study was composed of nine items. The questionnaire presented the acid and base reactants and products, and the students pictured their thoughts on how these substances change, and answered the reasons of their thoughts. Situation contexts of the questionnaire were divided into two groups: one kind of solute dissolved in a solvent, and two kinds of solute dissolved in a solvent. In this study, six levels of learning progression were assumed by combining material conservation logic, combination logic, proportion logic, and particle number conservation logic. By analyzing the data, Infit and Outfit values of Person reliability, Item reliability, MNSQ and ZSTD were obtained from the Rasch model. As a result of the analysis of data, it was found that lower levels of learning progression prevailed up to the younger grade students till $8^{th}$ grade. The higher levels of learning progression(Level 2~Level 5) prevailed up to the older grade students. However, higher levels of learning progression dropped sharply in Grade 12. The 5 level of learning progression was very low in all grades, and $9^{th}$ grade had highest percentage of students belonging to the 5 level. Interpretation of these unusual results suggests a future research related to explanation differences of textbooks.

• Geophysics and Geophysical Exploration
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• v.1 no.1
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• pp.31-42
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• 1998

Recently crosshole seismic tomography has come to be widely used especially for the civil engineering, because it can provide more detail information than any other surface method, although the resolution of tomogram will be inevitably deteriorated to some extent due to the limited wavefield aperture on the nonuniqueness of traveltime inversion. In addition, our field sites often consist of a high-velocity bed rock overlain by low-velocity rock, sometimes with a contrast of more than 45 percent, and furthermore the bed rock is folded. The first arriving waves can be then the refracted ones that travel along the bed rock surface for some source/receiver distances. Thus, the desirable first arrivals can be easily misread that cause severe distortion of the resulting tomogram, if it is concerned with (straight ray) traveltime inversion procedure. In this case, comparision with synthetic data (forward modeling) is a valuable tool in the interpretation process. Besides, abundant information is contained in the crosshole data. For instance, examination of tube waves can be devoted to detecting discontinuities within the borehole such as breakouts, faults, fractures or shear zones as well as the end of the borehole. Specific frequency characteristics of marine silty mud will help discriminate from other soft rocks. The aim of this paper is to present several strategies to analyze and interpret the crosshole data in order to improve the ability at first to determine the spatial dimensions of interwell anomalies and furthermore to understand the underground structures. To this end, our field data are demonstrated. Possibility of misreading the first arrivals was illustrated. Tube waves were investigated in conjunction with the televiewer images. Use of shot- and receiver gathers was examined to benefit the detectabilities of discontinuities within the borehole.

• Journal of Convergence for Information Technology
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• v.8 no.3
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• pp.25-32
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• 2018

This descriptive research is to find communication ability, general and social self-efficacy, and academic achievement in peer collaboration subject of nursing freshmen. The data were analyzed by SPSS/WIN 19.0. The communication ability was higher in the extroverts and high discussion preference ones(p=.01), females' social self-efficacy were higher than males'(p=.03), the general and social self-efficacy of the 'introverted' and 'middle' groups were higher than the extroverts'(p=.01). The social self-efficacy on the 'middle high', 'middle' and 'middle low' of self-evaluated school grades groups were higher than 'high' one's, even the academic achievement of 'high' group was the most(p=.01). There were negative correlations between communication ability and self-efficacy, and between social self-efficacy and academic achievement. And social self-efficacy affected on the academic achievement in peer collaboration subject($R^2=0.058$, p<.05). These results can be used as a basis for developing guidelines of nursing freshmen who have to complete a lot of theoretical and practical courses in university.

• Journal of Convergence for Information Technology
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• v.9 no.12
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• pp.98-103
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• 2019

The purpose of this study was to identify the correlation and level of Body Mass Index, Body Shape Dissatisfaction, Eating Behavior in college students. Methods: A total of 383 students were asked. The survey was analyzed by SPSS Win 21.0 program. 293 were female students and most of the students were normal in BMI(58.2%), and underweight students were the next(14.9%). There were positive correlation between body shape non satisfication and eating behavior and BMI(r=.587, p=.000; r=.174, p=.001), and negative correlation between body shape non satisfication and age and sleeping time. According to BMI the body shape non satisfication was different in normal and 1 stage obesity students. and 2 stage obesity and under weight students (F=2.993, p=.019;F=2.993, p=.109). As a result of this study, students with body mass index overweight have low body satisfaction, so it is necessary to educate the right dietary exercise therapy for weight management. And even underweight groups should be mediated so that they undergo normal diet behaviors, rather than restrained dietary behaviors, to maintain health.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.59-66
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• 2005

The main purpose of this paper is to describe a highly efficient common mid-point (CMP) data acquisition method for ground-penetrating radar (GPR) surveying, which is intended to widen the application of GPR. The most important innovation to increase the efficiency of CMP data acquisition is continuous monitoring of the GPR antenna positions, using a real-time kinematic Global Positioning System (RTK-GPS). Survey time efficiency is improved because the automatic antenna locating system that we propose frees us from the most time-consuming process-deployment of the antenna at specified positions. Numerical experiments predicted that the data density and the CMP fold would be increased by the increased efficiency of data acquisition, which results in improved signal-to-noise ratios in the resulting data. A field experiment confirmed this hypothesis. The proposed method makes GPR surveys using CMP method more practical and popular. Furthermore, the method has the potential to supply detailed groundwater information. This is because we can convert the spatially dense dielectric constant distribution, obtained by using the CMP method we describe, into a dense physical value distribution that is closely related to such groundwater properties as water saturation.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.941-950
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• 2021

This study was conducted to identify the factors affecting the health-promoting lifestyle of the school-age obese children. Method: Data Collection for this study was conducted form July 20 to August 2, 2019 using a structured questionnaire. We analyzed the collected data by frequency, percentage, ANOVA, t-test, Pearson's Correlation Coefficient, and Multiple Regression Analysis. Results: The factors affecting the health-promoting lifestyle of the subjects, multiple regression analysis results showed that Dietary Self-Efficacy(𝛽=.406, p=.001), Physical Activity Self-Efficacy(𝛽=.245, p=.038), Furthermore, the F statistics for the fitness of the estimated regression model were 6.34(p<.001), which was significant. The explanatory power was 24.2%. Conclusion: The results of this study showed that Dietary Self-Efficacy and Physical Activity Self-Efficacy of the school-age obese children was the most influential factor on health-promoting lifestyle. Consequently, the results of this study suggest that it is necessary to find ways to improve Dietary Self-Efficacy and Physical Activity Self-Efficacy in order to improve health-promoting lifestyle of nurses, and it is considered to be useful as basic data for developing intervention programs to improve health-promoting lifestyle.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.1070-1080
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• 2021

This study is a descriptive survey research on social network service addiction tendency and interpersonal relationships on college life adaptation among nursing students. The study period was from October 1 to 4, 2019, the survey was conducted for 228 first and third year nursing students located in G city. The collected data were analyzed with the SPSS 23.0 program using descriptive statistics, ANOVA, Pearson correlation coefficients, and multiple regression. The results of the study showed that there were differences in the subjects' college life adaptation depending on their gender (t=5.26, p<.001), daily average duration of using social network service (F=8.07, p<.001), and friends in real life (F=2.87, p=.037). College life adaptation had a significant correlation with social network service addiction tendency (r=-.31, p<.001) and interpersonal relationships (r=.52, p<.001), and social network service addiction tendency with interpersonal relationships had a significant correlation (r=-.17, p=.011). Factors that affected college life adaptation included interpersonal relationships (𝛽=.477, p<.001), gender (𝛽=-.198, p=.001), and daily average duration of using social network service (𝛽=-.177, p=.003), and the explanatory power of these factors was 37.8%. Based on the results of this study, it is thought that it is necessary to develop a program for a positive interpersonal relationship formation using social network service in order to improve the college life adaptation of nursing students.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.683-690
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• 2021

The purpose of this study was to confirm the degree of academic achievement among university students in the Department of Radiology(science) who are in the continuation of the COVID-19 situation and to investigate the effect of smart media literacy and ego-resilience on academic achievement. The research method was descriptive research. Data was 188 students collected from June 1 to July 31 in 2021 using structured questionnaires as students in the Department of Radiology(science). Collected data was analyzed using descriptive statistics, t-test, ANOVA, Cronbach's pearson's correlation, multiple regression analysis with SPSS/WIN 21.0. The result of the study showed that the academic achievement was 3.43, ego-resilience was 3.37 and smart media literacy was 2.94. There was a significant positive correlation between a academic achievement and smart media literacy, academic achievement and ego-resilience. Factors influencing academic achievement were smart media literacy, ego-resilience, major satisfaction and practice satisfaction. As a result of the above research. it is necessary to develop and apply curriculums, extra curriculums and educational programs that improve the smart media literacy and ego-resilience in order to improve the academic achievement. In addition, it is necessary to improve major satisfaction and practice satisfaction.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.229-239
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• 2021

This study is to identify the factors influencing the attitudes, behavior controls, and subjective norms related to COVID-19 vaccination on the intention of preventive behavior in K provincial residents. A total of 232 people agreed to participate in the study. Data were analyzed using descriptive statistics, t-test, ANOVA, correlation, and Hierarchical analysis. As a result of this study, the factors that had a statistically significant effect on the intention to conduct COVID-19 vaccination were perceived behavioral control (β=.39, p<.001) and attitude toward COVID-19 preventive behavior (β=.24, p<.001), followed by subjective norm (β=.24, p<.001). The explanatory power for this was 56.8%. The COVID-19 vaccine is an important means of ending the COVID-19 pandemic and helps prevent infection or worsening of COVID-19 and protect those around you. In the post-COVID-19 situation, it is necessary to improve the intention of vaccination against COVID-19 and to take active measures and strategies. At this point in time when COVID-19 vaccination is becoming more prevalent across the country, we hope that the intent of the COVID-19 vaccination action will translate into a COVID-19 vaccination action.