• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.697-702
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• 2023

Recently, with the introduction of drones, a core technology of the 4th industrial revolution, various convergence education using drones is being conducted in school education sites. In particular, drone theory and practice education is being conducted in connection with free semester classes and career exploration. The drone convergence education program has higher learner satisfaction than simple demonstration and practice education, and the learning effect is high due to direct practical experience. However, since practical education is being conducted for a large number of learners, it is impossible to restrict and control the flight of a large number of drones in a limited place. In this paper, we propose a monitoring system that allows the instructor to monitor multiple drones in real time and learners to recognize collisions between drones in advance when multiple drones are operated, focusing on education operated in schools. The communication module used in the experiment was equipped with GPS in Murata LoRa, and the server and client were configured to enable monitoring based on the location data received in real time. The performance of the proposed system was evaluated in an open space, and it was confirmed that the communication signal was good up to a distance of about 120m. In other words, it was confirmed that 25 educational drones can be controlled within a range of 240m and the instructor can monitor them.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.140-148
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• 1994

A qualification test was performed for the iron removal chemical cleaning of the secondary side of nuclear steam generators at the selected temperature, 1$25^{\circ}C$, higher than the standard application temperature, 93$^{\circ}C$. The field cleaning condition for a nuclear unit was tested in a bench scale test loop including a SUS 316 stainless steel autoclave with one gallon capacity as a test vessel. The kinetics of sludge dissolution, corrosion of the secondary side materials and change of solvent chemistry were monitored. Test results indicated that more thorough cleaning was accomplished in less than half of the cleaning time required at 93$^{\circ}C$. And the total corrosions of the secondary side materials were found to be less than the values at 93$^{\circ}C$. While the solvent is recirculated and heated by an external chemical cleaning equipment for the conventional 93$^{\circ}C$ process, the secondary side is heated by the lateral heat of the primary coolant without the recirculation of the cleaning solution, and the solvent is mixed by vigorous boiling induced by periodic ventilation for the high temperature process. The requirement that the reactor coolant pumps should be running during the cleaning operation is the major disadvantage of the high temperature process which also should be considered when chemical cleaning is planned for steam generators under operation.

• Education of Primary School Mathematics
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• v.26 no.2
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• pp.115-124
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• 2023

This study aimed to investigate elementary school teachers' interest in mathematics textbooks following the new change in the publication system for elementary mathematics textbooks. To achieve this, an online survey platform was used to conduct a survey of elementary school teachers in teaching grade 3-4 across the country, and the responses of 199 participants were analyzed to determine their interest in mathematics textbooks. The research results showed that elementary school teachers had high levels of interest in mathematics textbooks, particularly in informational and personal interest. Moreover, the stages at which teachers showed the highest level of interest were reinforcement interest and operational interest. Analysis of the differences in interest in mathematics textbooks based on personal variables showed significant differences depending on the teacher's experience in mathematics education training, satisfaction with mathematics textbooks, and whether they majored in mathematics education. Based on these findings, it can be inferred that elementary school teachers have a high level of informational interest in the characteristics, strengths, weaknesses, and materials related to authorized and approved mathematics textbooks, and their high level of personal interest in mathematics textbooks can have a positive effect in line with the goal of the new textbook system. Additionally, since many teachers showed a high level of interest in reinforcement interest, it is necessary to devise various ways to support teachers' creative use and reconstruction of mathematics textbooks.

• Journal of Service Research and Studies
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• v.13 no.1
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• pp.76-95
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• 2023

As information and communications technology-based "smart hospitals" and "digital healthcare" have become a hot topic in the healthcare field, hospital mobile apps are gaining attention; but, the utilization rate is low due to lack of publicity, unstable systems, and late updates. In this situation, systematic research is needed to increase the utilization rate of hospital mobile apps, but related research has been rare. Therefore, this study integrates the information systems success model (ISSM) from the technical perspective and the expectation-confirmation model (ECM) from the cognitive perspective to demonstrate the influence mechanism on the continuous use intention of hospital mobile apps. For this purpose, an online survey was conducted among 181 Korean adults who have used hospital mobile apps. The results of the structual equation modeling showed that most of the quality factors have significant effects on expectation confirmation, perceived usefulness, and satisfaction. Additionally, expectation confirmation significantly affects perceived usefulness and satisfaction, and both perceived usefulness and satisfaction significantly affect the continuous use intention of hospital mobile apps. This study is of importance in that it integrates the ISSM and ECM and applies them to the context of using hospital mobile apps, which are underutilized in the healthcare field, and provides practical implications for increasing the utilization rate of hospital mobile apps and operating effective and efficient services through the findings.

• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.45-55
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• 2009

The quality of railroad trackbed fills has been controlled by field measurements of density and bearing resistance of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. To overcome the defect, the compressional wave velocity was adopted as a control measure, in parallel with the advent of the new design procedure, and its measurement technique was proposed in the preliminary investigation. The key concept of the quality control procedure is that the target value for field compaction control is the compressional wave velocity determined at optimum moisture content using modified compaction test, and direct-arrival method is used for the field measurements during construction, which is simple and reliable enough for practice engineers to access. This direct-arrival method is well-suited for such a shallow and homogeneous fill lift in terms of applicability and cost effectiveness. The sensitivity of direct-arrival test results according to the compaction quality was demonstrated at a test site, and it was concluded that compressional wave velocity can be effectively used as quality control measure. The experimental background far the companion study (Park et al., 2009) was established through field and laboratory measurements of the compressional wave velocity.

• Journal of the Korea Society of Computer and Information
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• v.14 no.9
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• pp.11-19
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• 2009

A RAM-based Neural Net(RBNN) which has multi-discriminators is more effective than RBNN with a discriminator. Experience Sensitive Cumulative Neural Network and 3-D Neuro System(3DNS) that accumulate the features point improved the performance of BNN, which were enabled to train additional and repeated patterns and extract a generalized pattern. In recognition process of Neural Net with multi-discriminator, the selection of class was decided by the value of MRD which calculates the accumulated sum of each class. But they had a saturation problem of its memory cells caused by learning volume increment. Therefore, the decision of MRD has a low performance because recognition rate is decreased by saturation. In this paper, we propose the method which improve the MRD ability. The method consists of the optimum MRD and the matching ratio prototype to generalized image, the cumulative filter ratio, the gap of prototype response MRD. We experimented the performance using NIST database of NIST without preprocessor, and compared this model with 3DNS. The proposed MRD method has more performance of recognition rate and more stable system for distortion of input pattern than 3DNS.

• Journal of Digital Convergence
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• v.20 no.1
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• pp.25-32
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• 2022

The purpose of this study was conducted to develop adult distance literacy education program and verify its effects. The program was developed through the examination on factors affecting online literacy education and necessary analysis and feedback. Pre- and post-tests analyzing the effects of distance literacy education measuring academic understanding factor, learner satisfaction and satisfactory levels on the academic were administered to 49 adult literacy learners before and after a distance literacy education course. Also, this paper try to explore learners who participated in distance literacy education experience, change and that meaning. The results of the content analysis on the program are summarized as follows. First, there were statistically significant differences regarding academic understanding factor, learner satisfaction and perceived learning outcome satisfaction variables since distance literacy education program which is based on ARCS model start. In addition, learners were satisfied with replaying the learning videos several times, and the improved ability to use smart devices. But they expressed regrets about not being able to go to school and the difficulty of using the devices. It means that distance literacy education based on the ARCS model draw a positive learning conclusion. On the basis of these results, suggestions for further research were discussed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.159-166
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• 2023

This study analyzed what consumer characteristics affect the experience of using overseas direct purchase at a time when the overseas direct purchase market is rapidly increasing and consumers' interest in overseas direct purchase is increasing accordingly. For the study, personal data from the 2022 Korea Media Panel Survey were used, and data from 6,734 people who responded "yes" or "no" to whether or not to use overseas direct purchase among 9,941 total respondents were used for analysis. In addition, three variables (demographic, media utilization status, values and lifestyle) were selected among the items of the Korea Media Panel Survey. First, general characteristics were analyzed fo 6,734 people, then, Chi-square test and t-test were performed for comparative analysis between each variable according to the use of overseas direct purchase. Finally, logistic regression analysis was performed to identify the factors affecting overseas direct purchase. As a result of the analysis, 4 out of 5 demographic variables, 2 out of 3 media utilization variables, and 3 out of 7 values and lifestyle variables were derived as decisive factors for using overseas direct purchase. These results can be used to establish marketing strategies that can increase the use of consumers through domestic shopping malls, such as providing differentiated services for the sale of overseas direct shopping products on domestic shopping sites.

• Communications of Mathematical Education
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• v.36 no.1
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• pp.139-170
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• 2022

In relation to differentiated mathematics education, Russia has a longer experience in research and practice than Korea. The mathematics curriculum for 10-11 grades currently in use in Russia is a level-specific curriculum and consists of a basic level and an advanced level. And in Russia mathematics textbooks for 10-11 grades are also textbooks for each level. In this study, we analyzed basic level textbook and advanced level textbook written by the same author group among the textbooks 'Algebra and Introduction of Mathematical Analysis' of the 10th grade in Russia. To analyze the main learning contents and textbook descriptions that were added in advanced level the 'real numbers' and 'complex numbers' sections were studied. The main contents of basic and advanced level textbooks for 'functions', 'trigonometric functions', 'trigonometric equations', 'conversions of trigonometric expressions', and 'derivatives', which are included in both basic and advanced textbooks were compared and analyzed, and the descriptive characteristics of the definitions and theorems presented in the two levels of textbooks were also compared and analyzed. From the results of this study, it is expected that various information on the contents of various level textbooks of mathematics, the differences between textbooks for each level, and strategies for the composition of textbooks for various level can be accumulated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.197-208
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• 2022

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.