• Journal of Educational Research in Mathematics
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• v.27 no.4
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• pp.833-855
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• 2017

This study aims to reinvestigate the reason for introducing radian as a new unit to express the size of angles, what is the meaning of radian measures to use arc lengths as angle measures, and why is the domain of trigonometric functions expanded to real numbers for expressing general angles. For this purpose, it was conducted historical, mathematical and applied mathematical analyzes in order to research at multidisciplinary analysis of the radian concept. As a result, the following were revealed. First, radian measure is intrinsic essence in angle measure. The radian is itself, and theoretical absolute unit. The radian makes trigonometric functions as real functions. Second, radians should be aware of invariance through covariance of ratios and proportions in concentric circles. The orthogonality between cosine and sine gives a crucial inevitability to the radian. It should be aware that radian is the simplest standards for measuring the length of arcs by the length of radius. It can find the connection with sexadecimal method using the division strategy. Third, I revealed the necessity by distinction between angle and angle measure. It needs justification for omission of radians and multiplication relationship strategy between arc and radius. The didactical suggestions derived by these can reveal the usefulness and value of the radian concept and can contribute to the substantive teaching of radian measure.

• Communications for Statistical Applications and Methods
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• v.15 no.4
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• pp.563-585
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• 2008

This paper presents how to improve the efficiency and accuracy in the pricing and sensitivity evaluation for derivatives, since the need for the evaluation of complicated derivatives is increased. The Monte Carlo(MC) simulation using the quasi random number instead of pseudo random number can improve the elapsed time and accuracy for the valuation of European-type derivatives. However, the quasi MC simulation method has its limit for applying it in the multi-dimensional case such as American-type and path-dependent options due to the increased correlation between dimensions as the dimension of random numbers is increased. In order to complement this problem, we develop a modified method in which correlation values are controlled to be below a pre-specified value. Thus, this method is applicable for the pricing of either derivatives ill which underlying assets or risk factors are several or derivatives having path-dependent or early redemption property. Furthermore, we illustrate that it is important to take an appropriate grid interval for the use of finite difference method(FDM) by applying the FDM to one example of non-symmetrical butterfly spreads.

• Communications of Mathematical Education
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• v.20 no.3 s.27
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• pp.407-423
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• 2006

The reason why creativity becomes the important subject in 21th century is that it does an important role which solves many problems surrounding our whole life in this internationalization, globalization, knowledge-information age. But scholars who formerly researched the creativity-field explain the necessity of creativity with the internal and fundamental reasons. That is, scholars say that creative activities produce originative products and originality itself. And it is the root of which will be able to discover meaning of life and it -creativity - is successive activities that is demanded when individual life want to obtain important value by expressing one's inner world to the outside using creative resource. Recently, with the trends of present age and the educational needs, research about creativity is actively carried out and it draws out the results that creativity can be developed and enhanced through education and training. So, now many researches have focused on how to develop the creativity. Investigating those researches, we found that the recent issues of researches on creativity were changing and now they focused on creative instruction methods and behavioral factors. Especially, they were selected as the subject related to the creative education - creative instructional method and program, atmosphere in classroom, and factors of teacher. It means that the past researches which were a little bit conceptive have been changing to material ones which will be able to enhance creativity and its effect. So, in this research, we have developed the program for CPS(Creativity Problem Solving) and verified its effect.

• Journal for History of Mathematics
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• v.25 no.4
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• pp.53-67
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• 2012

Today, it is necessary to calculate orbits with high accuracy in space flight. The key words of Poincar$\acute{e}$ in celestial mechanics are periodic solutions, invariant integrals, asymptotic solutions, characteristic exponents and the non existence of new single-valued integrals. Poincar$\acute{e}$ define an invariant integral of the system as the form which maintains a constant value at all time $t$, where the integration is taken over the arc of a curve and $Y_i$ are some functions of $x$, and extend 2 dimension and 3 dimension. Eigenvalues are classified as the form of trajectories, as corresponding to nodes, foci, saddle points and center. In periodic solutions, the stability of periodic solutions is dependent on the properties of their characteristic exponents. Poincar$\acute{e}$ called bifurcation that is the possibility of existence of chaotic orbit in planetary motion. Existence of near exceptional trajectories as Hadamard's accounts, says that there are probabilistic orbits. In this context we study the eigenvalue problem in early 20th century in three body problem by analyzing the works of Darwin, Bruns, Gyld$\acute{e}$n, Sundman, Hill, Lyapunov, Birkhoff, Painlev$\acute{e}$ and Hadamard.

• Journal of Educational Research in Mathematics
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• v.16 no.3
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• pp.221-249
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• 2006

The object of this study is to understand the characteristics of mathematical knowledge that elementary 5th graders have regarding the statistical variation concept and the changes after taking lessons. This study includes a pretest to examine the characteristics of mathematical knowledge that elementary 5th graders have regarding the statistical variation concept. And It was followed by a lesson on statistical variation concept to be able to correct error which was revealed by the inspection, and to improve good points. It turned out that after five lessons on the statistical variation concept, the insufficient aspects were properly improved, and as for the points they already understand, they came to understand better than before. They came to consider the statical variation concept instead of the frequency, preponderance, average, stable traits for the optimum value. Also, through the lesson on drawing tables and graphs, they came to better understand them, analyzing correctly the exercises in which tables and graphs were combined. When comparing data sets whose general distributions and extents were similar, students came up with the right answers in a stable way by considering averages combining statistical variation too. Since they tended to interpret a situation with their own subjective views adding conditions, teachers need to examine the proper situation and conditions prior to the lessons on the statistical variation concept.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.3
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• pp.559-577
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• 2011

The purpose of this study was to investigate the effects of discourse-based math instructions on the students' mathematical attitudes and learning achievements by providing fifth graders with an opportunity to take active part in learning during math classes and applying discourse-based math instructions, which are to expand the speaking experiences as the most fundamental way to express ideas in communication. Those research efforts led to the following results: First, the discourse-based math instructions turned out to have positive influences on flexibility, will power, curiosity, reflection, and value of mathematical attitudes. When the results were reviewed before and after the instructions without considering the subvariables of attitude, there were statistically significant differences(p<0.01), which indicates that the discourse-based math instructions exerted very positive effects on the students mathematical attitudes. Second, there were no statistically significant effects in learning achievements between the experimental and comparative group, but the experimental group, which recorded low mean scores in the pre-test, increased their mean scores by 3.81 points in the post-test, which suggests that the discourse-based math instructions had positive influences on them. Third, the subjects' responses on the questionnaire on discourse-based instructions reveal that the discourse-based math instructional provided them with an opportunity to explore solutions in various ways. In short, discourse-based math instructions have positive influences on mathematical attitudes and are effective in increasing communication ability.

• Communications of Mathematical Education
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• v.36 no.1
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• pp.107-138
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• 2022

This study is a study that developed class materials that can apply Process-Focused Assessment to classes by paying attention to feedback using teacher learning community programs centered on teachers belonging to the same school in the field. In particular, this study was conducted with the aim of developing class materials applicable to actual classes. At this time, We thought about how to provide appropriate feedback when applying course-based evaluation in school field classes. It was conducted according to the procedure of data development research by Lee & Ahn(2021). As for the procedure of data development itself, an evaluation plan was established by establishing a strategy to reconstruct achievement standards and confirm understanding based on curriculum analysis. Next, an evaluation task, a scoring standard table, and a preliminary feedback preparation table were developed. In addition, based on these development materials, a learning guidance plan that can predict scenes when applying actual classes was developed as a result. This study has value as a practical study that can contribute to providing a link between theory and field schools. It is also meaningful in that it considered how the teacher would grasp when to provide feedback in performing rocess-Focused Assessment. Likewise, in providing feedback by teachers, it is meaningful in that it reflects in the data development how to prepare in advance and take classes according to the characteristics of the subject. Finally, it seems that the possibility of field application can be improved in that the results of the 4th class developed in this study are presented in a form applicable to the class directly in the field.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.337-347
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• 2018

Weather causes much of the risk of agricultural activity. For efficient farming, we need to use weather information. Modern agriculture has been developed to create high added value through convergence with state-of-the-art Information and Communication Technology (ICT). This study deals with the quality control algorithms of weather monitoring equipment through Ubiquitous Sensor Network (USN) observational equipment for efficient cultivation of cabbage. Accurate weather observations are important. To achieve this goal, the Korea Meteorological Administration, for example, developed various quality control algorithms to determine regularity of the observation. The research data of this study were obtained from five USN stations, which were installed in Anbandegi and Gwinemi from 2015 to 2017. Quality control algorithms were developed for flat line check, temporal outliers check, time series consistency check and spatial outliers check. Finally, the quality control algorithms proposed in this study can also identify potential abnormal observations taking into account the temporal and spatial characteristics of weather data. It is expected to be useful for efficient management of highland cabbage production by providing quality-controlled weather data.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.565-577
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• 2012

Various factors affecting teachers' self-confidence exist in math class using technology such as graphic calculators. For example, internal factors such as teachers' attitude and external factors such as school administrators or colleague's support can be considered. Pedagogical Technology Knowledge(PTK) is the very important factor which determines teacher's self-confidence in educational technology, and the development of PTK is composed of teacher's perception on the technology and its application and instrumentation. This study investigated 19 pre-service and current middle and high school teachers in the respect of their change of self-confidence, attitude, expertise on pedagogical technology, and quality of math class. These are anlayzed with the concept of instrumentation and instrumentalization through various experiences like graphic calculator, GPS and AutoGraph. The result indicated that constraints or obstacles did not affect much if teachers' attitude and self-confidence were strong. Particularly teachers' firm will to learn about technology and their confidence on its value are the critical factors in using technology for mathematics class.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.1
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• pp.243-262
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• 2017

This study has its purpose on improving mathematic education by analyzing the effects of the teaching and learning process which adopted 'FOCUS Problem Solving Steps' on student's mathematical problem solving ability and their mathematical attitude. The result is as follows. First, activities through FOCUS Problem Solving Steps showed positive effect on students' problem solving ability. Second, among mathematical attitudes, mathematical curiosity, reflection and value are proved to have statistically meaningful effect and from the result that analyzed changes of subject students, we could suppose that all 6 elements of mathematical attitude had positive effect. Third, by solving questions through FOCUS steps, students felt satisfaction when they success by themselves. If projects which adopted FOCUS Problem Solving Steps take effect continuously by happiness from the process of reviewing and reflecting their own fallacy and solving that, we might expect meaningful effect on students' problem solving ability. Through this study, FOCUS Problem Solving Steps had positive effect not only on students' mathematical problem solving ability but also on formation of mathematical attitude. As a result, it implies that FOCUS Problem Solving Steps need to be applied to other grades and fields and then studied more.