• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.254-266
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• 2021

Using forest resources involves solving complex and diverse tasks. At the same time, one of the key goals in the field is improving the quality of forest infrastructure. This direction requires adequate mathematical and economic justification. Moreover, creating an effective infrastructure will not only increase the accessibility and usage volumes of wood and other forest resources, but also contribute to the development of continuous and sustainable forest management. The existing practice of making decisions in terms of the organizational and technological aspects of logging, based on the personal experiences of managers or leading specialists in enterprises, hinders the achievement of constant optimal efficiency. The paper presents results that are a continuation of the research cycle of the authors' team in the fields of optimization and algorithmization of various logging processes. The focus of the study lies in the processing and movement of wood resources, the most valuable products of the investigated groups of enterprises. To this end, the paper presents a developed algorithm for determining an effective technological chain of transportation in logging operations, and for improving loading and unloading processing operations under dynamic natural and production conditions. This algorithm serves as the methodological basis for designing logging infrastructure in a dynamically changing environment.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1697-1707
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• 2021

The recent introduction of various high-dimensional modeling methods, such as radiomics and deep learning, has created a much greater diversity in modeling approaches for survival prediction (or, more generally, time-to-event prediction). The newness of the recent modeling approaches and unfamiliarity with the model outputs may confuse some researchers and practitioners about the evaluation of the performance of such models. Methodological literacy to critically appraise the performance evaluation of the models and, ideally, the ability to conduct such an evaluation would be needed for those who want to develop models or apply them in practice. This article intends to provide intuitive, conceptual, and practical explanations of the statistical methods for evaluating the performance of survival prediction models with minimal usage of mathematical descriptions. It covers from conventional to deep learning methods, and emphasis has been placed on recent modeling approaches. This review article includes straightforward explanations of C indices (Harrell's C index, etc.), time-dependent receiver operating characteristic curve analysis, calibration plot, other methods for evaluating the calibration performance, and Brier score.

• The Mathematical Education
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• v.60 no.4
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• pp.467-491
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• 2021

This study is a study on the coding mathematics curriculum that converges elementary and middle school mathematics and information subjects and a minimum coding game-based education method for this. For the past 3 years, the coding mathematics curriculum and educational methods to effectively operate the curriculum were studied by applying them to 6th graders of elementary school and 1st graders of middle school. As a result of the first year of research, the coding mathematics curriculum was modified to a coding environment including the mathematical concept of a three-dimensional coordinate space, and the three-dimensional object was improved to be output as a real 3D print. As a result of the 2nd year study, it was improved so that even low-level students can build buildings by introducing different level commands for each component of the building so that self-directed learning is possible. As a result of the 3rd year study, a teaching-learning strategy based on a minimal coding game was designed to induce an increase in the level of computational thinking, and evaluation and feedback for diagnosing computational thinking were developed. Educational methods to promote self-directed learning and computing thinking ability, and researched coding mathematics curriculum are meaningful for the research and practice of the convergence education of school mathematics and informatics.

• The Mathematical Education
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• v.61 no.3
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• pp.397-417
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• 2022

The purpose of this study is to discuss information literacy in mathematics education by comparatively analyzing mathematics education experts' perception of information processing and information literacy in mathematics education. We collected mathematics education experts' opinions using the modified Delphi method and focus group interviews, then analyzed their responses with an analytic framework through a constant comparative method. Even though we used different methods, we could compare their perceptions under the common themes. The findings are in three-folds. First, most experts focused only on the use of technological tools or statistics as a way of developing information literacy. In addition, even though mathematics education experts recognize the need for information literacy in mathematics education, their definition and meaning of information literacy somehow varied. Secondly, teachers as practitioners emphasized social competency which could be developed through information literacy. Thirdly, they asked for concrete and systematic plans for school practice in order to well develop information literacy in schools. Even though there were some differences in their perception of information literacy in mathematics education in terms of their prior experiences and background, it is very meaningful that there were commonalities among their perceptions which would allow us to find the ways of developing information literacy in mathematics education.

• 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.

• Communications of Mathematical Education
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• v.23 no.3
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• pp.735-760
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• 2009

Most of every teachers' life is occupied with his or her instruction, and a classroom is a laboratory for mutual development between teacher and students also. Namely, a teacher's professionalism can be enhanced by circulations of continual reflection, experiment, verification in the laboratory. Professional development is pursued primarily through teachers' reflective practices, especially instruction practices which is grounded on $Sch\ddot{o}n's$ epistemology of practices. And a thorough penetration about situations or realities and an exact understanding about students that are now being faced are foundations of reflective practices. In this study, at first, we explored the implications of earlier studies for discussing a teacher's practice. We could found two essential consequences through reviewing existing studies about classroom and instructions. One is a calling upon transition of perspectives about instruction, and the other is a suggestion of necessity of a teachers' reflective practices. Subsequently, we will talking about an instance of a middle school mathematics teacher's practices. We observed her instructions for a year. She has created her own practical knowledges through circulation of reflection and practices over the years. In her classroom, there were three mutual interaction structures included in a rich expressive environments. The first one is students' thinking and justifying in their seats. The second is a student's explaining at his or her feet. The last is a student's coming out to solve and explain problem. The main substances of her practical know ledges are creating of interaction structures and facilitating students' spontaneous changes. And the endeavor and experiment for diagnosing trouble and finding alternative when she came across an obstacles are also main elements of her practical knowledges Now, we can interpret her process of creating practical knowledge as a process of self-directed professional development when the fact that reflection and practices are the kernel of a teacher's professional development is taken into account.

• Information Systems Review
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• v.13 no.2
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• pp.1-16
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• 2011

Recently, many companies have started to manage and support CoPs formally at the organizational level because of strategic usability of CoP. These companies are also seeking ways to motivate CoP members to actively participate in their groups. Accordingly, this paper proposes one way of increasing CoP activities by rearranging CoP members. In practice, active CoP members often lead their groups. Therefore, rearranging members can, eventually, be one method to motivate more individuals to participate in CoP activities. This paper first suggests a new approach in order to improve knowledge sharing activities at the organizational level based on rearranging members of current CoPs. Second, a mathematical model is presented which maximizes total BLS (Balanced Level Score) of company A with several constraints. Then a real world problem is changed to a popular problem, VRP to solve this problem. Third, the solution program was developed to find a meaningful solution.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.2
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• pp.317-332
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• 2011

The purpose of this study is to suggest an effective plan for teaching the definition of prism by integrating and analyzing the theories related to the instruction of definitions. The subjects in this study to realize these objectives were as follows. First, it looks to theoretical backgrounds regarding the instruction of the definition of solid by functions of definition in mathematics education. Second, it explores the instructional way to form the definition of solid through function of definition, by analyzing the unit of solid in the 6th grade. Third, after conducting the real practice with the 5th graders who before learn solid in 6th curriculum, according to plan of instruction, it examined student's response and testify its effectiveness, and then propose a teaching scheme which is designed to be useful based on the outcomes. In terms of theoretical background, it investigated the precedent research in relation to the instruction of the definition that mathematical definition is not given perfectly but the process of making knowledge that mathematization activity is necessary. It investigated the effects of the instruction of definitions, based on the effects of teaching and interviews with the 5th graders, and analysis of student's handout. The followings were the results of this study. First, 'Making Definitions' activities through remove counterexample process was possible to analytic thinking not intuitively thinking, and it effects the extend of awareness in definition that definition is not fixed but various. Second, it need the step of organize terms that is useful on solid's definition through activate of background knowledge. Third, it is effective that explore characters of the solids after construct the solids. Fourth, interactive discussion that students correct their mistakes each other through mathematical communication and they can think developmental is useful on making definition more than individual study.

• Communications of Mathematical Education
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• v.28 no.2
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• pp.235-253
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• 2014

This study aims to develop strategies for improving the affective characteristics of Korean students based on results from international achievement tests. In pursuing the goal, different research methods are employed including a) analysis of the theories and literature regarding the affective domains included in PISA and TIMSS studies; b) analysis of the current situation and needs of Korean students with respect to the affective factors based on PISA and TIMSS results; c) case studies of best practices in relation to students' affective domains in Korea and abroad; and d) development of strategies for improving and supporting Korean students' affective characteristics. Especially, this paper deals with the analysis of the results from in-depth interviews and class observations, so as to identify the current situation and best practice cases of students' affective characteristics education in Korea. The results are classified into a) curriculum, which is in turn divided into national curriculum and reconstruction of curriculum school and classroom; and b) teaching, learning and evaluation, which is in turn divided into learner characteristics, motivation, teaching strategies, class grouping, activities and interaction, question and feedback, evaluation methods, and evaluation tools. Support plans in terms of school and social environments are also suggested based on the results.

• Journal of Educational Research in Mathematics
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• v.25 no.4
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• pp.717-754
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• 2015

As a design research, this study aims to identify students' collaborative problems solving patterns using the Wiki and design factors triggering MKB(mathematical knowledge building) in virtual environment. For 70 days, 14 Korean secondary gifted students, who enrolled in calculus II courses in one of gifted institutions in Korea, solved 10 math problems together using the Wiki. In this study, I considered five design factors; motivation, practice of LaTeX, norms of participation, epistemic agency, and two types of educational settings. The primary pattern emergent in students' collaborative problem solving process is identified as 'solutions and refutations' along the double helix consisting of the constructive line and the critical line, which is very similar to the pattern of 'Conjectures and Refutations'(Lakatos, 1976). Despite that most participants had difficulty in using LaTeX for mathematical expressions, this study shows that Wikis are valuable tools for providing Korean secondary students opportunities to learn social virtue such as humility and courage (Lampert, 1990), which is considered to be have been neglected in Korean educational environment but is emphasized as precious for doing mathematics in the field of mathematics education.