• 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.

• 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.

• The Korean Journal of Applied Statistics
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• v.31 no.2
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• pp.253-263
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• 2018

Internet addiction in adolescents is an important social issue. In this study, sparse partial least-squares regression (SPLS) was applied to internet addiction data in Korean adolescent samples. The internet addiction score and various clinical and psychopathological features were collected and analyzed from self-reported questionnaires. We considered three PLS methods and compared the performance in terms of prediction and sparsity. We found that the SPLS method with the hierarchical likelihood penalty was the best; in addition, two aggression features, AQ and BSAS, are important to discriminate and explain latent features of the SPLS model.

• Journal of Korean Elementary Science Education
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• v.33 no.2
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• pp.231-241
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• 2014

This study is subject to compare the STEAM and the STEM education of Korea, the U.K., and the U.S. to find their differences and similarities, as well as the implications in implementing the STEAM education in Korea. In order to accomplish this, the educational objectives, contents and topics, teaching and learning methods, subjects and timing for education, and convergence curriculum were compared; also, after choosing the representative program of each country, a cross-comparative analysis was done for the teaching and learning method distribution ratio, content element distribution ratio, program distribution ratio, STEAM domain ratio, curriculum structure and domain ratio, frequency of inquiry process, basic inquiry, integrated inquiry frequency, hourly basic inquiry, and integrated inquiry process. As a result, it was possible to obtain 77 programs, a total of 656 class hours of Korea, 65 programs and 846 class hours of the U.S., and 75 programs and 774 class hours of the U.K. The results are as follows: Korea's STEAM and the U.K. and the U.S.' STEM all include science, technology, engineering, arts, and mathematics, but in terms of frequency, Korea's STEAM has higher figure in arts. However, the U.K. and the U.S. have higher frequency of debate and discussion, and there were many cases of a student, after receiving feedback from other students, modifying the work.

• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.131-142
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• 2017

The number of hospital admissions for pneumonia tends to increase annually and even more, pneumonia, the fifth leading causes of death among elder adults, is one of top diseases in terms of hospitalization rate. Although mainly bacteria and viruses cause pneumonia, the weather is also related to the occurrence of pneumonia. The candidate weather variables are humidity, amount of sunshine, diurnal temperature range, daily mean temperatures and density of particles. Due to the delayed occurrence of pneumonia, lagged weather variables are also considered. Additionally, year effects, holiday effects and seasonal effects are considered. We select the related variables that influence the occurrence of pneumonia using penalized generalized linear models.

• Journal of the Korean earth science society
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• v.28 no.4
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• pp.405-414
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• 2007

This study examined students' achievement of Earth science in the Trends in International Mathematics and Science Study (TIMSS) that was conducted with 46 participating countries in 2003 and analyzed average percent-correct items for Earth science were analyzed in terms of subcategory, item type and cognitive domain. In addition, items showing a gender difference and a big difference in the test scores of Korean and international students were analyzed. Korean students performed higher than the international average, especially in the astronomy-related topic and in the cognitive domain of 'reasoning and analysis'. In an analysis of the five items that Korean students scored lower than the international average, Korean students performed not so well in demonstrating what they understood with drawings and writings. Korean female students showed a difficulty more than male students did in multiple-choice items that asked recalling of factual knowledge and demonstrated lack of confidence in the items that they have not learned yet. Based on the result content organization of Earth science curriculum and ways to improve teaching and loaming methods were recommended.

• Communications of Mathematical Education
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• v.26 no.2
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• pp.205-220
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• 2012

In this article convergent sequences with natural number terms are investigated and the behaviors of tails and limits of these natural number sequences are explored. Firstly this study showed how the pre-service teachers response to the intuitive limit definition using "getting closer" for constant sequences. As a case of convergent natural sequences, the sequences in which the latter term is determined by the sum of digit squares of the former term are considered. To exploring these sequences the computational and charting capabilities of spreadsheets are utilized and some mathematical findings are obtained. Spreadsheet can be instrumentalized by teachers or students to provide a laboratory-like environment to explore a mathematical problem.

• Korean Journal of Childcare and Education
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• v.11 no.3
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• pp.129-148
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• 2015

The purpose of this study was to look into trends in research concerned with children's counting in Korea. A total of 59 studies on counting including journal articles, master's & doctoral theses were analyzed in terms of the period of time, content, and research methods. The results showed that 1) ${\frac{1}{3}}$ of the total studies on counting were published in 2001~2005, 2) the most frequent content was the developmental trend of young children's counting ability and then the relation between counting ability and various mathematical competence, 3) most of the studies targeted normal early childhood children from 3~5 years old and used the quantitative method. These results showed that the domestic research on counting have limits in the research topics, subjects, and methodology. The researcher presents three suggestions for further research. Frist, topics that are not enough revealed in the previous studies, for examples, counting backwards, counting by collections such as tens, fives, twos, and counting errors in young children need to be further studied. Second, counting behavior and ability of young children under 3 years olds need to be investigated. Third, there is a need to increase the studies using qualitative methods.

• Industrial Engineering and Management Systems
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• v.14 no.3
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• pp.221-235
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• 2015

Risk assessment is an important phase of risk management. It is the stage in which risk is measured thoroughly to achieve effective management. Some factors such as probability and impact of risk have been used in the literature related to construction projects. Because in high-rise projects safety issues are paramount, this study has tried to develop a quantifying technique that takes into account three factors: probability, impact and Safety Performance Index (SPI) where the SPI is defined as the capability of an appropriate response to reduce or limit the effect of an event after its occurrence with regard to safety pertaining to a project. Regarding risk-related literatures which cover an uncertain subject, the proposed method developed in this research is based on a fuzzy logic approach. This approach entails a questionnaire in which the subjectivity and vagueness of responses is dealt with by using triangular fuzzy numbers instead of linguistic terms. This method returns a Risk Critical Point (RCP) on a zoning chart that places risks under categories: critical, critical-probability, critical-impact, and non-critical. The high-rise project in the execution phase has been taken as a case study to confirm the applicability of the proposed method. The monitoring results showed that the RCP method has the inherent ability to be extended to subsequent applications in the phases of risk response and control.

• Earthquakes and Structures
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• v.13 no.3
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• pp.255-265
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• 2017

In this paper, an efficient shear deformation theory is developed for wave propagation analysis in a functionally graded beam. More particularly, porosities that may occur in Functionally Graded Materials (FGMs) during their manufacture are considered. The proposed shear deformation theory is efficient method because it permits us to show the effect of both bending and shear components and this is carried out by dividing the transverse displacement into the bending and shear parts. Material properties are assumed graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents; but the rule of mixture is modified to describe and approximate material properties of the functionally graded beams with porosity phases. The governing equations of the wave propagation in the functionally graded beam are derived by employing the Hamilton's principle. The analytical dispersion relation of the functionally graded beam is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions, the depth of beam, the number of wave and the porosity on wave propagation in functionally graded beam are discussed in details. It can be concluded that the present theory is not only accurate but also simple in predicting the wave propagation characteristics in the functionally graded beam.