• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1586-1591
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• 2022

Kirchhoff-Love plate (KLP) equation is a well established theory for a description of a deformation of a thin plate under certain outer source. Meanwhile, analysis of a vibrating plate in a frequency domain is important in terms of obtaining the main frequency/eigenfunctions and predicting the vibration of plate. Among various modal analysis methods, dynamic mode decomposition (DMD) is one of the efficient data-driven methods. In this work, we carry out DMD based modal analysis for KLP where thin plate is under effects of sine-type outer force. We first construct discrete time series of KLP solutions based on a finite difference method (FDM). Over 720,000 number of FDM-generated solutions, we select only 500 number of solutions for the DMD implementation. We report the resulting DMD-modes for KLP. Also, we show how DMD can be used to predict KLP solutions in an efficient way.

• The Mathematical Education
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• v.50 no.2
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• pp.213-231
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• 2011

The purpose of this study is to analyze the 6th graders' understanding of the concepts of variable on various aspects of school algebra. For this purpose, the test of concepts of variable targeting a sixth-grade class was conducted and then two students were selected for in-depth interview. The level of mathematics achievement of the two students was not significantly different but there were differences between them in terms of understanding about the concepts of variable. The results obtained in this study are as follows: First, the students had little basic understanding of the variables and they had many cognitive difficulties with respect to the variables. Second, the students were familiar with only the symbol '${\Box}$' not the other letters nor symbols. Third, students comprehended the variable as generalizers imperfectly. Fourth, the students' skill of operations between letters was below expectations and there was the student who omitted the mathematical sign in letter expressions including the mathematical sign such as x+3. Fifth, the students lacked the ability to reason the patterns inductively and symbolize them using variables. Sixth, in connection with the variables in functional relationships, the students were more familiar with the potential and discrete variation than practical and continuous variation. On the basis of the results, this study gives several implications related to the early algebra education, especially the teaching methods of variables.

• Education of Primary School Mathematics
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• v.22 no.1
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• pp.1-12
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• 2019

This study examined the attention and attention shift of general students and mathematically gifted students about pattern by the types of mathematical patterns. For this purpose, we analyzed eye movements during the problem solving process of 5th general and mathematically gifted students using eye tracker. The results were as follows: first, there was no significant difference in attentional style between the two groups. Second, there was no significant difference in attention according to the generation method between the two groups. The diversion was more frequent in the incremental strain generation method in both groups. Third, general students focused more on the comparison between non-contiguous terms in both attributes. Unlike general students, mathematically gifted students showed more diversion from geometric attributes. In order to effectively guide the various types of mathematical patterns, we must consider the distinction between attention and attention shift between the two groups.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.11-20
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• 1999

Because conventional spatial databases process the spatial information that is valid at current time, it is difficult to manage historical information efficiently which has been changed from the past to current. Recently, there are rapid increasing of interest to solve this problem so that makes databases to support historical information as well as spatial management at the same time. It can be eventually used in a various application areas. The formal semantics in a database is used to represent database structures and operations in order to prove the correctiveness of them in terms or mathematics. It also plays an important role in database to design a database and database management system. So in this paper, we suggest spatiotemporal domain, object, data, and spatiotemporal geometric/topological operations. And we not only formalize relational algebra/calculus using formal semantics for a spatiotemporal data model, but also show the example of real orld with them.

• Journal of Educational Research in Mathematics
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• v.27 no.3
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• pp.411-430
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• 2017

This study examined the understanding of 24 pre-service teachers about the three contexts for constructing the exponential graphs. The three contexts consisted of the infinite points context (2009 revision curriculum textbook method), the infinite straight lines context (French textbook method), and the continuous compounding context (2015 revision curriculum textbook method). As the result of the examination, most of the pre-service teachers selected the infinite points context as easier context for introducing the exponential graph. They noted that it was the appropriate method because they thought their students would easily understand, but they showed the most errors in the graph presentation of this method. These errors are interpreted as a lack of content knowledge. In addition, a number of pre-service teachers noted that the infinite straight lines context and continuous compounding context were not appropriate because these contexts can aggravate students' difficulty in understanding. What they pointed out was interpreted in terms of knowledge of content and students, but at the same time those things revealed a lack of content knowledge for understanding the continuous compounding context. In fact, considering the curriculum they have experienced, they were not familiar with this context, continuous compounding. These results suggest that pre-service teacher education should be improved. Finally, some of the pre-service teachers mentioned that using technology can help the students' difficulties because they considered the design of visual model.

• Korean Journal of Schizophrenia Research
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• v.22 no.2
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• pp.34-41
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• 2019

Objectives: This study was performed to examine the effects of the public attention to 'crime of schizophrenia' on the use of mental health services in patients with schizophrenia using big data analysis. Methods: Data on the frequency of internet searches for 'crime of schizophrenia' and the patterns of mental health service utilization by patients with schizophrenia spectrum disorders by month were collected from Naver big data and the Health Insurance Review and Assessment Services in Korea, respectively. Their correlations in the same and following month for lagged effect were examined. Results: The number of outpatients correlated negatively with public attention to 'crime of schizophrenia' in the same month. The lagged relationship between public attention and the number of admissions in psychiatric wards was also found. In terms of sex differences, the use of outpatient services among female patients correlated negatively with public attention in the same month while the number of male patients' admissions in both same and following month correlated positively with public attention. Conclusion: These findings suggested that public attention to 'crime of schizophrenia' could negatively affect illness behavior in patients with schizophrenia.

• Journal of Science Education
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• v.41 no.3
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• pp.480-498
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• 2017

This study analyzed the errors of 6th graders of elementary school in problem solving process of the measurement domain. By analyzing the errors that students make in solving difficult problems, this study tried to draw implications for teaching and learning that can help students reach their achievement standards. First, though the students were given enough time to deal with problems, the fact that about 30~60% of students, based upon the problems given, can't solve them show that they are struggling with a part of measurement domain. Second, it was confirmed that students' understanding of the unit of measurement, such as relationship between units, was low. Third, the students have a low understanding in terms of the fact that once the base is set in a triangle then the height can be set accordingly and from which multiple expressions, in obtaining the area of the triangle, can be driven.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.558-564
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• 2004

This research investigated the connection between science textbook contents in Democratic People's Republic of Korea (DPRK) and those in Republic of Korea (ROK). Both text books in the field of earth science were analyzed and classified into 70 categories based on the Third International Mathematics and Science Study (TIMSS). Comparison was specifically made between the elementary and middle school text books of both countries; the result are as follows: First, the scope and the level of the textbooks' contents are quite different between DPRK and ROK. Text books in the South are much limited in concepts and terms than those in the North. In contrast, textbooks in DPRK are written mainly to explain concepts. Second, there are many common contents of the textbooks in DPRK and Republic of Korea. The level and scope of the contents in Republic of Korea are more inquisitive, quantitative and detailed than those in DPRK. Third, we found content connections in science textbooks between primary and secondary schools in both countries: 27 items (38.5%) are related in ROK and 19 items (27.1%) in DPRK.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.5
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• pp.329-339
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• 2019

Recently, the advancement of information and communication technology(ICT) is expanding the connectivity through Internet of Things(IoT), and the media of connection is also expanding from wire/cable transmission to broadband wireless communication, which has significantly improved mobility. This hyperconnectivity has become a key element of the fourth industrial revolution, whereas the supervisory control network of purification plants in korea is operated as a communication network separated from the outside, thereby lagging in terms of connectivity. This is considered the best way to ensure security, and thus there is hardly any consideration of establishing alternatives to operate an efficient and stable communication network. Moreover, security for management of a commercialized communication network and network management solution may be accompanied by immense costs, making it more difficult to make new attempts. Therefore, to improve the conditions for the current supervisory control network of purification plants, this study developed a industrial security L2 switch that supports modbus TCP(Transmission Control Protocol) communication and encryption function of the transmission section. As a result, the communication security performance improved significantly, and the cost for implementing the network management system using Historical Trend and information of HMI(Human Machine Interface) could be reduced by approximately KRW 200 million. The results of this study may be applied to systems for gas, electricity and social safety nets that are infrastructure communication networks that are similar to purification plants.

• Journal of the Korea Society of Computer and Information
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• v.19 no.4
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• pp.149-158
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• 2014

The rapidly changing 21st-century knowledge and information society is emphasizing converged education that crosses various academic fields. In particular, the society expected the cultivation of the talent who balance scientific creativity and artistic sensitivity by adding arts to the existing converged education revolving around science and technology. However, at present, most STEAM education has been actively conducted with a focus on science and technology, whereas the subject of arts has been regarded or utilized as a supplementary means. Its problem is that the educational characteristics and values of art education have not been effectively utilized in educational terms and this could lead to superficial integrated education. In this respect, this study had the knowledge of various fields, such as science, technology, and mathematics, utilized usefully during the process of experiencing and creating arts. Accordingly, this study designed an education programs as with the case of Nam-Jun Baek who expanded the dominion of arts by creatively utilizing his own time's scientific technologies. In this educational process, the target program was developed in a manner that enables EPL to be utilized essentially as the study's knowledge-based tool and medium. The results of applying this educational program in 5th-grade elementary school students showed that the program has positive effects on the creative attributes of the students.