• Journal of the Korean Society of School Health
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• v.28 no.3
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• pp.200-210
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• 2015

Purpose: This study aimed to examine the use of smart phones and their relationship with self-efficacy and academic achievement among students in 5th to 6th grade. Methods: 954 students in $5^{th}$ to $6^{th}$ grade were selected from three elementary schools in K City through purposive sampling. Data of 591 respondents were analyzed by $x^2$ test, ANOVA, correlation analysis and multiple regression analysis using the SPSS/WIN program. Results: First, 64% of the students possessed a smart phone and female students used their phone more than male students. 47.5% of the students said they first used a smartphone in their $5^{th}$ grade and 11.7% said in their 6th grade. Second, heavier use of smart phones was related to a lower level of self-efficacy (p<.001). Third, the more the students used a smart phone, the less they achieved in academic performance (Korean language: p<.001, mathematics: p<.01). Finally, the biggest factor influencing smart phone addiction was longer use of smart phones. In addition, lower self-efficacy and lower ability to adapt to difficult tasks were the factors influencing the increase in smart phone addiction. Less use of smart phones and higher self-efficacy resulted in higher achievement in academic performance. Conclusion: It is essential to decrease students' use of smart phones and improve their self-efficacy and academic performance. Intervention programs to reduce the use of smart phones should include a profound interest, a personality-oriented educational environment and sufficient dialogues with students at home, schools and the local society, beyond simple regulations to prevent adverse effects.

• Education of Primary School Mathematics
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• v.19 no.1
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• pp.31-45
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• 2016

In this study, the case of error became the object of learning, and the investigator applied these cases to an actual class and established three study problems in order to achieve the purpose of this study. The results of analysis of students' errors in figure based on before achievement test are shown as follows: First, the most errors occurred in the figure was the ones from deficient mastery of prerequisite concepts and definitions. Specially, the errors from deficient mastery of prerequisite concepts and definitions have the majority. it is very high ratio even if it considers an influence of an evaluation question item. so, I think it is necessary to teach concept related figure above all. Second, as the results of application 'finding errors' to a class, there is a meaningful difference in the mathematical achievement and reasoning ability within significance level 5%. This means 'finding errors' is one of the teaching method that it develops the mathematical achievement and reasoning ability.

• 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.

• Communications of Mathematical Education
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• v.24 no.1
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• pp.49-65
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• 2010

The purpose of this study is to encourage the role of domain to consider the teaching of the concept of functions in modeling real situations. To do this, it is analyzed that how to introduce the concept of functions and linear functions in textbooks treated in the 1st grade and the 2nd grade of middle school. This study also reviewed the role of domain in representational activities for modeling real situations using linear functions. In these reviews, it found that many textbooks do not consider the domain in the equations of functions and these graphs and several text books used linear functions for modeling real situations which are not represented by linear functions contextually. It is concluded that the domain of function is an important concept that will be considered any representational activities for functions.

• Communications of Mathematical Education
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• v.24 no.1
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• pp.1-27
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• 2010

This study intends to provide implications about sluggish use of calculators in our case by analyzing the math textbook of U.S. Macmillan/McGraw-Hill along with the tendency of paying more attention to math class using technologies. From the results of analysis, this textbook deals with various methods over around 3.3% of all pages, using calculators across all grades from 1st to 6th grade. In particular, it offers guidance into three types such as 'Choose a Computation Method', 'You can also use a calculator.', and 'TECHNOLOGY LINK', while particularly it is impressive in the perspective of using calculators as one of calculation strategies. And case studies of usage in textbooks describe 8 different perspectives as an example-represent; solve problems or equations; develope or demonstrate conceptual understanding; analyze; compute or estimate; describe, explain or justify; choose appropriate calculation method; determine a calculated answer's reasonableness. Reflecting on the fact that we still use calculators in a passive way, there are considerable implications to us.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.1
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• pp.29-34
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• 2017

Recently, studying chaotic dynamic have been concerned by many researchers in areas of physics, chemistry, mathematics, engineering and social science. Especially, model of addiction, happiness, family and love become major research subjects in the social science. Among these models, love is one of the four emotions that human being have. There are many definitions for love, however, each definitions of love does not coincide with each other. Recently, one of the most important efforts for research is love and it is represented by derivative equation. Then they try to find nonlinear or chaotic behavior from this derivative equation. This paper propose Gaussian fuzzy membership function in order to make external force that are close to action and awareness of human based on love model of Romeo and Juliet with external force. This paper also confirms the existence of nonlinear characteristics through time series and phase portrait.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.9-15
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• 2013

An effect of a spiral turbulent ring, so-called Shchelkin spiral, on a detonation performance was studied experimentally for acetylene and oxygen mixture. A couple of dynamic pressure transducers were used to calculate a detonation wave velocity by a time difference between two pressure peaks. In addition, impulse was measured by a load cell and the impulse was used to analyze the spiral effect on the detonation performance. A CFD analysis was adopted to calculate mass flow rates of the propellants and the minimum filling time. The maximum velocity and pressure were measured at the equivalence ratio of 2.4, and the measured values showed similar trend to C-J conditions calculated from CEA. For the shorter chamber with the short spiral, the maximum detonation velocity was appeared. In contrast, the longer chamber without the spiral showed the maximum thrust performance.

• Journal of Convergence for Information Technology
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• v.9 no.12
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• pp.54-61
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• 2019

Recently, IITS (intelligent integrated transportation system) has been important topic in Smart City related industry. As a main objective of IITS, prevention of traffic jam (due to car accidents) has been attempted with help of advanced sensor and communication technologies. Studies show that car accident has certain correlation with some factors including characteristics of location, weather, driver's behavior, and time of day. We concentrate our study on observing auto correlativity of car accidents in terms of time of day. In this paper, we performed the ARIMA tests including ADF (augmented Dickey-Fuller) to check the three factors determining auto-regressive, stationarity, and lag order. Summary on forecasting of hourly car crash counts is presented, we show that the traffic accident data obtained in Korea can be applied to ARIMA model and present a result that traffic accidents in Korea have property of being recurrent daily basis.

• Communications of Mathematical Education
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• v.35 no.4
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• pp.425-444
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• 2021

In this study, under the assumption that the goal pursued in measurement area can be reached through the composition of the measurement activity considering the mathematical process, the method of summing the interior angles of a triangle using the measurement error was applied to the 4th grade class of the elementary school. Results of the study, first, students were able to recognize the possibility of measurement error by learning the sum of the interior angles of a triangle using the measurement error. Second, the discussion process based on the measurement error became the basis for students to attempt mathematical justification. Third, the manipulation activity using the semicircle was recognized as a natural and intuitive way of mathematical justification by the students and led to generalization. Fourth, the method of guiding the sum of the interior angles of a triangle using the measurement error contributed to the development of students' mathematical communication skills and positive attitudes toward mathematics.

• 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.