• Korean Journal of Mathematics
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• v.29 no.2
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• pp.345-353
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• 2021

The object of the present paper is to investigate the nature of Riemann solitons on generelized D-conformally deformed Kenmotsu manifold with hyper generalized pseudo symmetric curvature conditions.

• Korean Institute of Interior Design Journal
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• no.12
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• pp.91-99
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• 1997

Alvar Aalto has pursued National Romanticism, cultural art movement in scandinavian peninsula, organic concepts of growth and suitability, comprehensive view of nature including a possibility of coexistance of human-being and the nature well harmonized. For instance, his design expressed local features of the nature, human emotions instead of geometical arts and mathematical principles. It is noteworthy today that he built up the identity with satrical architecture vocabularies, different from modern arch-itechtural idiology. The characte-ristics of his design related to interior architecture are collectively as follows; The first, Space discontinuity of the interior and exterior, gradual process by joints which are inclined to collage with many shapes in plan and section of the space and such joints are adjusted by sensual ways and stressed with inner collectivity in his works. The second, He pursued the architectural orderfor modern irreqularity, various changes and sensual harmonies. As result, free curved line, fan shape and irregular modeling were individually expressed by technics of natural features and national characteristics of Finland. The third, Organic synthesis. A harmony through med-ums in its space, materials and space effectiveness relations are made and expressed for mixed design especially harmonized of all the materials he planned, entire harmony with total design, itemized details, materials and furnitures in entire space. The fourth, The interest of the nature based on his sense harmonized with nature made him mainly use native materials, lumbers and red bricks masonry and showed and arranged various interior sky light and grazed in to let natural light in, harmony with garden to sensually cohere to the nature and courtyard, etcetera. His major subject are to direct architectural developments through the nature and human-being in his works. At this point, it is considered that his direction of the locality and independence as a human-being made the concepts of organic space structure possible.

• Communications of Mathematical Education
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• v.34 no.1
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• pp.17-39
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• 2020

The purpose of this study is to analyze the mathematical beliefs of students and teachers by Latent Class Analysis(LCA). This study surveyed 60 teachers about beliefs of 'nature of mathematics', 'mathematic teaching', 'mathematical ability' and also asked 1850 students about beliefs of 'school mathematics', 'mathematic problem solving', 'mathematic learning' and 'mathematical self-concept'. Also, this study classified each student and teacher into a class that are in a similar response, analyzed the belief systems and built a profile of the classes. As a result, teachers were classified into three types of belief classes about 'nature of mathematics' and two types of belief classes about 'teaching mathematics' and 'mathematical ability' respectively. Also, students were classfied into three types of belief classes about 'self concept' and two types of classes about 'School Mathematics', 'Mathematics Problem Solving' and 'Mathematics Learning' respectively. This study classified the mathematics belief systems in which students were categorized into 9 categories and teachers into 7 categories by LCA. The belief categories analyzed through these inductive observations were found to have statistical validity. The latent class analysis(LCA) used in this study is a new way of inductively categorizing the mathematical beliefs of teachers and students. The belief analysis method(LCA) used in this study may be the basis for statistically analyzing the relationship between teachers' and students' beliefs.

• Communications of Mathematical Education
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• v.23 no.3
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• pp.545-562
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• 2009

This study is trying to analyze characteristics of mathematical thinking processes of the mathematical gifted students in an objective and a systematic way, by using "Protocol Analysis Method"and "Problem Behavior Graph" which is suggested by Newell and Simon as a qualitative analysis. In this study, four middle school students with high achievement in math were selected as subjects-two students for mathematical gifted group and the other two for control group also with high scores in math. The thinking characteristics of the four subjects, shown in the course of solving problems, were elicited, analyzed and compared, through the use of the creative test questionnaires which were supposed to clearly reveal the characteristics of mathematical gifted students' thinking processes. The results showed that there were several differences between the two groups-the mathematical gifted student group and their control group in their mathematical talents. From these case studies, we could say that it is significant to find out the characteristics of mathematical thinking processes of the mathematical gifted students in a more scientific way, in the sense that this result can be very useful to provide them with the chances to get more proper education by making clear the nature of thinking processes of the mathematical gifted students.

• Honam Mathematical Journal
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• v.5 no.1
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• pp.45-69
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• 1983

The hermitian structures on complex manifolds have been studied by several mathematicians ([1], [2], and [3]), and the Kähler structure on hermitian manifolds have been so much too ([6], [12], and [15]). There has been some gradual progress in studying the invariant forms on Grassmann manifolds ([17]). The purpose of this dissertation is to prove the Theorem 3.4 and the Theorem 4.7, with relation to the nature of complex Grassmann manifolds. In $\S$ 2. in order to prove the Theorem 4.7, which will be explicated further in $\S$ 4, the concepts of the hermitian structure, connection and curvature have been defined. and the characteristic nature about these were proved. (Proposition 2.3, 2.4, 2.9, 2.11, and 2.12) Two characteristics were proved in $\S$ 3. They are almost not proved before: particularly. we proved the Theorem 3.3 : $G_{k}(C^{n+k})=\frac{GL(n+k,C)}{GL(k,n,C)}=\frac{U(n+k)}{U(k){\times}U(n)}$ In $\S$ 4. we explained and proved the Theorem 4. 7 : i) Complex Grassmann manifolds are Kahlerian. ii) This Kähler form is $\pi$-fold of curvature form in hyperplane section bundle. Prior to this proof. some propositions and lemmas were proved at the same time. (Proposition 4.2, Lemma 4.3, Corollary 4.4 and Lemma 4.5).

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.175-182
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• 1993

The complex nature of low flow transport and tranformation of nonconservative pollutants in natural streams with pools and riffles has been investigated using a numerical solution of a proposed mathematical model that is based on a set of mass balance equations describing hydrodynamic processes (advection, dispersion, and mass exchange mechanicms in streams and in storage zones) and chemical processes (reaction or decay). In this study, a mathematical model (named "Storage-Transformation Model") has been developed to predict adequately the non-Fickian nature of mixing and transformation mechanisms for decaying substances in natural streams under low flow conditions. Comparisons between the concentration-time curves predicted usingthe proposed model and the measured stream data shows that the Storage-Transformation Model yields better agreements in the goneral shape, peak concentration and time to peak than the 1-D dispersion model. The result of this study also demonstrates the differences between transport in pool-and-riffle streams versus transport in more uniform channels. The proposed model shows significant improvement over the conventional 1-D disperision model in predicting natural mixing and stroage processes in streams through pools and riffles.

• Research in Mathematical Education
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• v.22 no.2
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• pp.99-121
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• 2019

This article looks back and also looks forward at the values aspect of school mathematics teaching and learning. Looking back, it draws on existing academic knowledge to explain why the values construct has been regarded in recent writings as a conative variable, that is, associated with willingness and motivation. The discussion highlights the tripartite model of the human mind which was first conceptualised in the eighteenth century, emphasising the intertwined and mutually enabling processes of cognition, affect, and conation. The article also discusses what we already know about the nature of values, which suggests that values are both consistent and malleable. The trend in mathematics educational research into values over the last three decades or so is outlined. These allow for an updated definition of values in mathematics education to be offered in this article. Considering the categories of values that might be found in mathematics classrooms, an argument is also made for more attention to be paid to general educational values. After all, the potential of the values construct in mathematics education research extends beyond student understanding of and performance in mathematics, to realising an ethical mathematics education which is important for thriveability in the Fourth Industrial Revolution. Looking ahead, then, this article outlines a 4-step values development approach for implementation in the classroom, involving Justifying, Essaying, Declaring, and Identifying. With an acronym of JEDI, this novel approach has been informed by the theories of 'saying is believing', self-persuasion, insufficient justification, and abstract construals.

• Communications of the Korean Mathematical Society
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• v.13 no.3
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• pp.655-681
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• 1998

Discontinuous solutions or interfaces are common in nature, for examples, shock waves or material interfaces. However, their numerical computation is difficult by the feature of discontinuities. In this paper, we summarize the numerical approaches for discontinuities and interfaces appearing mostly in the system of hyperbolic conservation laws, and explain various numerical methods for them. We explain two numerical approaches to handle discontinuities in the solution: shock capturing and shock tracking, and illustrate their underlying algorithms and mathematical problems. The front tracking method is explained in details and the level set method is outlined briefly. The several applications of front tracking are illustrated, and the research issues in this field are discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.1
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• pp.299-322
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• 2020

Vehicular ad hoc networks (VANETs) enable wireless communication between vehicles and roadside infrastructure to provide a safer and more efficient driving environment. However, due to VANETs wireless nature, vehicles are exposed to several security attacks when they join the network. In order to protect VANETs against misbehaviours, one of the vital security requirements is to revoke the misbehaved vehicles from the network. Some existing revocation protocols have been proposed to enhance security in VANETs. However, most of the protocols do not efficiently address revocation issues associated with group signature-based schemes. In this paper, we address the problem by constructing a revocation protocol particularly for group signatures in VANETs. We show that this protocol can be securely and efficiently solve the issue of revocation in group signature schemes. The theoretical analysis and simulation results demonstrate our work is secure against adversaries and achieves performance efficiency and scalability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3284-3306
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• 2018

This study proposes a method to develop an authoring system(GeoMaTree) for diverse trees that constitute a virtual landscape. The GeoMaTree system enables the simple, intuitive production of an efficient structure, and supports real-time processing. The core of the proposed system is a procedural modeling based on a mathematical model and an application that supports digital content creation on diverse platforms. The procedural modeling allows users to control the complex pattern of branch propagation through an intuitive process. The application is a multi-resolution 3D model that supports appropriate optimization for a tree structure. The application and a compatible function, with commercial tools for supporting the creation of realistic synthetic images and virtual landscapes, are implemented, and the proposed system is applied to a variety of 3D image content.