• Kyungpook Mathematical Journal
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• v.58 no.2
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• pp.399-426
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• 2018

Cofinite graphs and cofinite groupoids are defined in a unified way extending the notion of cofinite group introduced by Hartley. These objects have in common an underlying structure of a directed graph endowed with a certain type of uniform structure, called a cofinite uniformity. Much of the theory of cofinite directed graphs turns out to be completely analogous to that of cofinite groups. For instance, the completion of a directed graph Γ with respect to a cofinite uniformity is a profinite directed graph and the cofinite structures on Γ determine and distinguish all the profinite directed graphs that contain Γ as a dense sub-directed graph. The completion of the underlying directed graph of a cofinite graph or cofinite groupoid is observed to often admit a natural structure of a profinite graph or profinite groupoid, respectively.

• Journal of Educational Research in Mathematics
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• v.27 no.4
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• pp.663-678
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• 2017

Semiotic studies in mathematical education have been based on Saussure, Peirce, and Frege and many prior researches have explored the concepts in a perspective of semiotics. However, the relationship among semiotical elements and the formation and the evolution of a conception are still ambiguous and veiled in many aspects. This thesis is intended to show how a conception was formed and evolved by expression, which is an element of semiotics. In this process, I sought to partially illuminate the relationship among expressions, concepts, and objects.

• Journal for History of Mathematics
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• v.30 no.3
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• pp.137-162
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• 2017

The Chinese algebraic method, the tian yuan shu, was developed during Song period (960-1279), of which Li Ye's works contain the earliest testimony. Two 18th century editors commentated on his works: the editor of the Siku quanshu and Li Rui, the latter responding to the former. Korean scholar Nam Byeong-gil added another response in 1855. Differences can be found in the way these commentators considered mathematical objects and procedures. The conflicting nature of these commentaries shows that the same object, the quadratic equation, can beget different interpretations, either a procedure or an assertion of equality. Textual elements in this paper help modern readers reconstruct different authors' understandings and reconsider the evolution of the definition of the object we now call 'equation'.

• Korean Journal of Computational Design and Engineering
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• v.6 no.4
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• pp.271-276
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• 2001

A geometric kernel is the library of core mathematical functions that defines and stores 3D shapes in response to users'commands. We developed a light geometric kernel suitable to develop CAD/CAM application systems. The kernel contains geometric objects, such as points, curves and surfaces and a minimal set of functions for each type but does not contain lots of modeling and handling functions that are useful to create and maintain complex shapes from an idea sketch. The kernel was developed on MS-Windows NT using C++ with STL(Standard Template Library) but it is compatible with UNIX environments. This paper describes the structure of the kernel including several components: base, math, point sequence curve, geometry, translators. The base kernel gives portability to applications and the math kernel contains basic arithmetic and their classes, such as vector and matrix. The geometry kernel contains points, parametric curves, and parametric surfaces. A neutral fie format and programming and document styles are also presented in this paper.

• Korean Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.1-14
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• 1998

This paper introduces non-manifold offsetting operations, which add or remove a uniform thickness from a given non-manifold model. Since these operations can be applied to not only solids but also wireframe or sheet objects, they are potentially useful for pipeline modeling, sheet metal and plastic part modeling, tolerance analysis, clearance checking, constant-radius rounding and filleting of solids, converting of abstracted models to solids, HC too1 path generation and so on. This paper describes mathematical properties and algorithms for non-manifold offsetting. In this algorithm, a sufficient set of tentative faces are generated first by offsetting all or a subset of the vertices, edges and faces of the non-manifold model. And then they are merged into a model using the Boolean operations. Finally topological entities which are within offset distance are removed. The partially modified offsetting algorithms for wireframes or sheets are also discussed in order to provide more practical offset models.

• Journal of Drive and Control
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• v.9 no.3
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• pp.1-7
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• 2012

This paper deals with the issue of model reference adaptive control strategy to control the injection molding machine. Prior to controller design, a pair of transfer functions are derived for the injection and dwelling process based on mathematical models of components. As external disturbances to examine the robustness of the proposed controller, nozzle clogging and contraction of molded objects are considered and realized by proportional valve. The overall simulation system, consisting of hydraulic components, controller and sensors, is implemented using the components of commercial software SimulationX. The simulation results confirm the proposed scheme's efficiency and robustness.

• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.432-445
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• 2016

A random profile is the result of a process, the output of which is a function instead of a scalar or vector quantity. In the nature of these objects, two main dimensions of "functionality" and "randomness" can be recognized. Valuable researches have been conducted to present control charts for monitoring such processes in which a regression approach has been applied by focusing on "randomness" of profiles. Performing other statistical techniques such as hypothesis testing for different parameters, comparing parameters of two populations, ANOVA, DOE, etc. has been postponed thus far, because the "functional" nature of profiles is ignored. In this paper, first, some needed theorems are proven with an applied approach, so that be understandable for an engineer which is unfamiliar with advanced mathematical analysis. Then, as an application of that, a statistical test is designed for mean of continuous random profiles. Finally, using experimental operating characteristic curves obtained in computer simulation, it is demonstrated that the presented tests are properly able to recognize deviations in the null hypothesis.

• Education of Primary School Mathematics
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• v.4 no.1
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• pp.31-41
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• 2000

There has been much concern and worry about executing school curriculum from the year 2000 because the seventh curriculum is based on the complicated' differentiated education' concept. Now the new textbook has been developed according to the curriculum. This paper will reinforce the understanding of the curriculum and textbook in school math. In order to do this, this paper will present questions on three subjects to help school teachers and people related to math education to probe and discuss the benefits and problems of teaching math using the new textbook. The three subjects are based on the contents included in certain chapters of the math textbook. These are 1) understanding mathematics concepts using manipulatives or concrete objects, 2) doing math projects or problem solving activities 3) learning mathematics using calculators. furthermore, it is emphasized in this paper that math teachers must keep in mind that they should execute instruction in their own way using the 'textbook' not as a bible but as a guideline.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.292-302
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• 2022

The radar tomographic imaging is based on the Radar Cross-Section "RCS" of the materials of a shape under examination and investigation. The RCS varies as the conductivity and permittivity of a target, where the target has a different material profile than other background objects in a scene. In this research paper, we use Hierarchical Performance Modeling "HPM" and a framework developed earlier to determine/spot bottleneck(s) for pattern recognition of materials using a combination of the Single Layer Perceptron (SLP) technique and tomographic images in radar systems. HPM provides mathematical equations which create Objective Functions "OFs" to find an average performance metric such as throughput or response time. Herein, response time is used as the performance metric and during the estimation of it, bottlenecks are found with the help of OFs. The obtained results indicate that processing images consumes around 90% of the execution time.

• Education of Primary School Mathematics
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• v.11 no.1
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• pp.59-74
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• 2008

Mathematical knowledge is not exact definition but the supposition. Considering the nature of mathematics, realization of mathematics teaching which pursues critical thinking and rationality would be our problems. Accordingly, I set the subject of this study whether learning of constructivist discussion, which induces reflective thinking through communicating with others by expression with language of mathematical thinking in discussion, is effective against attitude on Mathematics and Mathematics achievement and study themes are as follows; A. Is learning of constructivist discussion effective against attitude on Mathematics? A-1. Is there any difference of self-conception on the subject between experimental group applied to learning of constructivist discussion and comparative group? A-2. Is there any difference of attitude on the subject between experimental group applied to learning of constructivist discussion and comparative group? A-3. Is there any difference of learning habits on the subject between experimental group applied to learning of constructivist discussion and comparative group? B. Is learning of constructivist discussion effective against mathematics achievement? The objects of study are 30 children of one class in the third grade of elementary school in Seoul for experimental group, and another one class with 30 children is comparative group. Study results and conclusion based on those results are as follows; First, students make reflective thinking through communication each other, therefore, instructor should create discussion environment for communication to express and form their mathematical thinking. Next, adaptability in student's mathematics activities and mathematical ideas should be permissible, and those should become divergent thinking. However, this study analyzed comparative results from only two each class having enrollment of thirty in the third grade. Accordingly, results from students in various grades and environment that are required to get more significant conclusion statistically.