• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.941-946
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• 2023

To improve the lift, cruise speed, and range of eVTOL aircraft, which are being considered as future transportation vehicles, this paper introduces the concepts of Tilt Rotor and Tandem Wing to the aircraft. We developed an aircraft and conducted flight experiments to obtain flight videos and flight logs. The results of the analysis of the flight videos and flight logs showed that the aircraft's moment was excessively forward and the attitude was not recovered. To address this problem, we modified the wing incidence angles and surface areas in XFLR5 to obtain the optimal pitching moment coefficients to ensure vertical stability. We then analyzed the redesigned aircraft, developed using CATIA, through XFLR5. The results of this study provide valuable insights, suggesting that the incorporation of Tilt Rotor and Tandem Wing designs can contribute to achieving stable pitching moment coefficients. This innovative approach offers a promising avenue to significantly enhance vertical stability in UAM vehicles, paving the way for future advancements in the field.

• Education of Primary School Mathematics
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• v.26 no.4
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• pp.317-332
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• 2023

Mathematical modeling activities hold the potential for diverse applications, involving the transformation of real-life situations into mathematical models to facilitate problem-solving. In order to assess the cognitive, affective, and social dimensions of students' engagement in mathematical modeling activities, this study conducted sessions with ten groups of fifth-grade elementary school students. The ensuing processes and outcomes were thoroughly analyzed. As a result, each group effectively applied mathematical concepts and principles in creating mathematical models and gathering essential information to address real-world tasks. This led to notable shifts in interest, enhanced mathematical proficiency, and altered attitudes towards mathematics, all while promoting increased collaboration and communication among group members. Based on these analytical findings, the study offers valuable pedagogical insights and practical guidance for effectively implementing mathematical modeling activities.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.3
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• pp.310-323
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• 2023

Urbanization and income distribution issues are global interest, and the results of studies on the impact of urbanization on income inequality are different for each country and period. This study analyzes the impact of urbanization on income inequality using regional data from 2000-2021. In particular, serial correlation, spatial dependence, and common factor effects of the Gini coefficient are confirmed and analyzed through a dynamic spatial panel regression model. As a result, urbanization has a positive effect on reducing income inequality. Therefore, it is necessary to continuously promote regional urbanization to improve the income distribution problem. Areas with already high urbanization rates should reduce income inequality by narrowing the wage gap by expanding training opportunities for low-skilled workers, and need to come up with measures to prevent counter-urbanization.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.92-101
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• 2023

To solve the problem of climate change, carbon neutrality has now become a necessity rather than an option. Hydrogen is not only a energy storage that can supplement the intermittent production of renewable energy, but is also considered a good alternative in the field of utilization as it does not emit carbon dioxide after reaction. In order to revitalize hydrogen vehicles, one of the fields of hydrogen utilization, the construction of hydrogen station infrastructure must be preceded. Prioritization of risk factors is necessary for efficient operation and risk assessment of hydrogen stations, but due to the short operation period of domestic hydrogen stations, there is a lack of frequency data on accidents and their reliability is low. In this study, we aim to identify the causes and consequences of deviations in hydrogen stations through HAZOP analysis. Additionally, we intend to analyze them using Fuzzy-AHP. Through this, we intend to derive the decision values for the causes of deviations in hydrogen stations and apply them to hydrogen accident cases and risk assessments to confirm the reliability and utility of the data.

• The Journal of Korean Academic Society of Nursing Education
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• v.30 no.1
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• pp.29-38
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• 2024

Purpose: This study aimed to investigate student nurses' satisfaction by type of clinical practicum and to determine predictors of clinical competence in pediatric nursing. Methods: A total of 189 Junior and Senior student nurses across seven colleges in the Busan Metropolitan City were enrolled in the study. The participants completed a structured questionnaire containing items about their learning satisfaction with different types of pediatric nursing practicums and their clinical competence. Data were analyzed using the mean, standard deviation, independent t-test, ANOVA, and multiple regression analysis. Results: Regarding satisfaction with each type of clinical practicum, the mean satisfaction score (out of 10) was 8.18±2.26 for on-site clinical rotations and 7.35±2.20 for alternative practicums. Among the different types of alternative practicum approaches, those with a satisfaction score of 7 or higher included fundamental nursing skills, watching videos, simulation etc., while those with a satisfaction score of less than 6 were virtual simulation and problem-based learning. The predictors of clinical competence in pediatric nursing were learning satisfaction with practice, school year, and alternative practicum, accounting for 35.0% of the variance in clinical competency. Conclusion: It would be helpful to combine on-site clinical rotations with alternative practicum approaches and to develop various alternative practice programs using simulation practice, virtual reality, immersive interactive systems, and standardized patients to enhance students' clinical competency.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.5
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• pp.384-391
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• 2023

In modern electronic warfare, a number of radar emitters are in operation, causing radar receivers to receive high-density signal pulses that occur simultaneously. To analyze the radar signals more accurately and identify enemies, the sorting process of high-density radar signals is very important before analysis. Recently, machine learning algorithms, specifically K-means clustering, are the subject of research aimed at improving the accuracy of radar signal sorting. One of the challenges faced by these studies is that the clustering results can vary depending on how the initial points are selected and how many clusters number are set. This paper introduces a repeated K-means clustering algorithm that aims to accurately cluster all data by identifying and addressing false clusters in the radar sorting problem. To verify the performance of the proposed algorithm, experiments are conducted by applying it to simulated signals that are generated by a signal generator.

• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.159-175
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• 2024

In order to solve the problem of calculating the reasonable completed bridge state of a self-anchored hybrid cable-stayed suspension bridge (SA-HCSB), this paper proposes an analytical method. This method simplifies the main beam into a continuous beam with multi-point rigid supports and solves the support reaction forces. According to the segmented catenary theory, it simultaneously solves the horizontal forces of the main span main cables and the stay cables and iteratively calculates the equilibrium force system on the main beam in the collaborative system bridge state while completing the shape finding of the main span main cable and stay cables. Then, the horizontal forces of the side span main cables and stay cables are obtained based on the balance of horizontal forces on the bridge towers, and the shape finding of the side spans are completed according to the segmented catenary theory. Next, the difference between the support reaction forces of the continuous beam with multiple rigid supports obtained from the initial and final iterations is used to calculate the load of ballast on the side span main beam. Finally, the axial forces and strains of each segment of the main beam and bridge tower are obtained based on the loads applied by the main cable and stay cables on the main beam and bridge tower, thereby obtaining analytical data for the bridge in the reasonable completed state. In this paper, the rationality and effectiveness of this analytical method are verified through a case study of a SA-HCSB with a main span of 720m in finite element analysis. At the same time, it is also verified that the equilibrium force of the main beam under the reasonably completed bridge state can be obtained through iterative calculation. The analytical algorithm in this paper has clear physical significance, strong applicability, and high accuracy of calculation results, enriching the shape-finding method of this bridge type.

• Journal of The Korean Association For Science Education
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• v.28 no.5
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• pp.424-437
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• 2008

In this study, we collected teachers' opinions with regard to the effects of the instruction using analogy generation, the disadvantages of the instruction, the problem-solving methods of the instruction, and the teacher's role in it, and accordingly tried to investigate its effectiveness with the analysis of students' academic achievements and motivation, and through the student's interview, after applying the activities of creating generated analogies, finding the difference between the objects and comparisons, and presenting new-known genetics concepts as the students themselves generated analogies. As a result of a teachers' workshop on instruction using analogy development, it was expected to have a positive effect on students' understanding of scientific concepts in genetics, which were found to be difficult for students to understand in learning biology. Students found analogy examples for concepts in genetics in daily life, compared their analogs to those of peers, and examined inconsistencies between targets and analogs through the process of discussion, which finally led to their correct perception of scientific concepts in genetics. In addition, instruction using student-generated analogies proved to have a more positive effect on improving academic achievement and motivating learning, compared with traditional expository instruction.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.475-485
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• 2024

In many regions of Korea, including the Four Major Rivers, the seriousness of the problem of algal blooms due to eutrophication of water quality is being raised.In this study, in order to solve these social problems, we manufactured a filter using natural mineral fusion (red illite, zeolite, germanium ceramic, selenium ceramic, carbon ceramic) and independently developed a tank system for green algae experiments to observe and determine the stages of change in water quality. In order to study ways to improve water quality through quantitative analysis, 1 ton of severely polluted green algae water from the Nak dong River region was stored in a water tank and exposed to ultraviolet rays in the same environment as the Nak dong River. Then, the same environment as the Nak dong River was created. The results were derived from a 5-week water quality test. The results of this experiment confirmed that green-colored cyano bacteria were significantly reduced just by the turbidity results. The results were obtained through a request to the Korea Testing & Research Institute located in Changwon-si, Gyeong sang nam-do. CI-(chlorine ion) and NH3-N(ammonia nitrogen) had the effect of saving every week. The device used in this study was made of natural minerals free of heavy metals that are harmless to the human body and nature through long-term consideration and exploration to kill and prevent various strains living in water. Green purification system using natural hydrogen generating mineral filter were effective a non-chemical and physical methods. The results of this study are one way to contribute to the serious problems caused by green algae in many countries, and will contribute to the water quality environment by preventing the waste of environmental resources, improving the health of the people, and increasing the ability to purify environmental water quality at home and abroad.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.125-132
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• 2024

Optical satellite images are being used for national security and collection of information, and their utilization is increasing. However, it acquires low-quality images that are not suitable for the user's requirement due to weather conditions and time constraints. In this paper, a deep learning-based conversion of image and colorization model referring to high-resolution SAR images was created to simulate the occluded area with clouds of optical satellite images. The model was experimented according to the type of algorithm applied and input data, and each simulated images was compared and analyzed. In particular, the amount of pixel value information between the input black-and-white image and the SAR image was similarly constructed to overcome the problem caused by the relatively lack of color information. As a result of the experiment, the histogram distribution of the simulated image learned with the Gray-scale image and the high-resolution SAR image was relatively similar to the original image. In addition, the RMSE value was about 6.9827 and the PSNR value was about 31.3960 calculated for quantitative analysis.