• 대한수학교육학회지:수학교육학연구
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• 제21권2호
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• pp.135-148
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• 2011

우리나라 중학교 수학 2에서는 공리의 역할을 하는 명제를 공리라는 명시 없이, 실험에 의해 확인한 옳은 결과로만 받아들여 증명에 사용한다. 그러나 공리 개념은 경험적 입증과 연역적 증명, 직관기하와 논증기하, 증명과 증명이 아닌 것의 차이를 이해하는데 매우 중요한 것이다. 본 연구의 교과서 분석과 영재학생들을 대상으로 한 인식조사 결과는, 공리와 증명의 취급에 대하여 우리나라 교과서가 가진 한계와 문제점을 보여주고 있다.

• 한국수학교육학회지시리즈A:수학교육
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• 제44권2호
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• pp.179-200
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• 2005

In this article, we compared and analyzed the Korean 7th National Mathematics textbooks and Harcourt Math textbooks in America focused on the area of geometry for the elementary school students. We expect that this article would contribute to the elementary school teacher for the reorganization of the elementary school mathematics curriculums.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.31-41
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• 2008

This paper deals with the energy saving problem of the follower aircraft in the loose leader-follower formation geometry in which the lateral separation between formation members is more than a wingspan of the leader aircraft. This formation geometry offers no drag benefit, but has a strategic advantage. In the case of loose formation flight, the follower aircraft usually consumes more energy than the leader aircraft because the follower aircraft should use more thrust to maintain given formation geometry, especially during the turning phase from the outside of the leader"s flight path or join-up phase. A formation control scheme based on the energy maneuverability is proposed in this paper. To design the proposed control law, the velocity command is designed using feedback linearization for the horizontal formation geometry and then coverts it to the altitude command using the energy equation. Numerical simulation is performed to verify the effectiveness of the proposed controller.

• 대한수학교육학회지:학교수학
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• 제8권2호
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• pp.215-237
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• 2006

본 연구는 국가수준 학업성취도에 따라 구분된 학생들의 성취수준별로 기하 문제해결에서 어떤 특정을 보이는지를 탐색하려 하였다. 기초학력, 보통학력, 우수학력 학생 3 명씩을 동질그룹으로 구성하여 교사의 도움 없이 비정형적인 기하 문제를 해결하게 하였고, 관찰을 통해 성취수준별로 기하 개념 발달 수준이 어떠한지, 문제 해결의 방법을 선택할 때 어떤 접근을 하는지를 분석하였다. 기초학력 학생들은 모양과 실용 기하의 개념 수준에서 문제해결에서 무엇을 할 수 있는가에 초점을 둔 물리적, 구체적 행동을 보였고, 보통학력 학생들은 실용 기하와 유클리드 기하의 수준에서 문제해결을 위해 무엇을 해야 하는가에 초점을 두어 문제해결의 여러 가지 방법을 탐색했으며, 우수학력 학생들은 실용 기하와 유클리드 기하의 수준에서 일반화와 정당화를 통해 문제해결의 본질에 접근하려 하였다. 본 연구는 이에 따라 학생들의 수준별 수학 학습을 지도하는 것에 대한 시사점을 제안하였다.

• 한국수학교육학회지시리즈A:수학교육
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• 제4권1호
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• pp.1-15
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• 1966

In accordance with the tendency of Modern Mathematics laying emphasis on Mathematical structure, that is, on axioms, it is necessary for students to be interested in structure of Geometry on Mathematics Education. In fact, it is of importance not only to obtain new ideas but also to forget old ones in the development of Mathematics. Most students do not understand the Mathematical significance of axioms, and do not know what Mathemetical truth is. Now Non-Euclidean Geometry offers opportunity to understand the essence of Mathematics better, and is no less effective than Euclidean Geometry in training student in logical inference. This thesis is a study with regard to what should be taught and how student should be guided at High school Mathematics. Chiefly Hyperbolic Geometry is discussed in connection with Abosolute Geometry. As Non-Euclidean Geometry has not appeared in our curriculum, some experiments are required before putting it into actual curriculum to find out how much students understand and how much pedagogically useful it can be. This is only a. presentation of a tentative plan, which needs to be criticized by many teachers.

• 한국CDE학회논문집
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• 제20권1호
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• pp.44-54
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• 2015

Solving partial differential equations (PDEs) on a manifold setting is frequently faced problem in CAD, CAM and CAE. However, unlikely to a regular grid, solutions for those problems on a triangular mesh are not available in general, as there are no well-established intrinsic differential operators. Considering that a triangular mesh is a powerful tool for representing a highly-complicated geometry, this problem must be tackled for improving the capabilities of many geometry processing algorithms. In this paper, we introduce mathematically well-defined differential operators on a triangular mesh setup, and show some examples of their applications. Through this, it is expected that many CAD/CAM/CAE application will be benefited, as it provides a mathematically rigorous solution for a PDE problem which was not available before.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.238-239
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• 2006

Nozzle geometry influences gas dynamics making sprayed particle behavior one of the most important parameters in cold spray process. Gas flows at the entrance convergent section of the nozzle takes place at relatively high temperature and are subsonic. Thus, this region is a very suitable environment for heating spray particle. In this study, numerical simulation and experiments were conducted to investigate the effect of nozzle contour, entrance geometry of nozzle and powder injection position at nozzle on the cold spray process. The process changes were observed through numerical simulation studies and the results were used to find a correlation with coating properties.

• 대한수학교육학회지:수학교육학연구
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• 제11권2호
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• pp.363-384
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• 2001

The purpose of this thesis is, through analysing the characteristics of the definitions in Korean school mathematics textbooks, to explore the levels of them and to make suggestions for definition - teaching as a mathematising activity, Definitions used in academic mathematics are rigorous. But they should be transformed into various types, which are presented in school mathematics textbooks, with didactical purposes. In this thesis we investigated such types of transformation. With the result of this investigation we tried to identify the levels of the definitions in school mathematics textbooks. And in school mathematics textbooks there are definitions which carry out special functions in mathematical contexts or situations. We can say that we understand those definitions, only if we also understand the functions of definitions in those contexts or situations. In this thesis we investigated the cases in school mathematics textbooks, when such functions of definition are accompanied. With the result of this investigation we tried to make suggestions for definition-teaching as an intellectual activity. To begin with we considered definition from two aspects, methods of definition and functions of definition. We tried to construct, with consideration about methods of definition, frame for analysing the types of the definitions in school mathematics and search for a method for definition-teaching through mathematization. Methods of definition are classified as connotative method, denotative method, and synonymous method. Especially we identified that connotative method contains logical definition, genetic definition, relational definition, operational definition, and axiomatic definition. Functions of definition are classified as, description-function, stipulation-function, discrimination-function, analysis-function, demonstration-function, improvement-function. With these analyses we made a frame for investigating the characteristics of the definitions in school mathematics textbooks. With this frame we identified concrete types of transformations of methods of definition. We tried to analyse this result with van Hieles' theory about levels of geometry learning and the mathematical language levels described by Freudenthal, and identify the levels of definitions in school mathematics. We showed the levels of definitions in the geometry area of the Korean school mathematics. And as a result of analysing functions of definition we found that functions of definition appear more often in geometry than in algebra or analysis and that improvement-function, demonstration-function appear regularly after demonstrative geometry while other functions appear before demonstrative geometry. Also, we found that generally speaking, the functions of definition are not explained adequately in school mathematics textbooks. So it is required that the textbook authors should be careful not to miss an opportunity for the functional understanding. And the mathematics teachers should be aware of the functions of definitions. As mentioned above, in this thesis we analysed definitions in school mathematics, identified various types of didactical transformations of definitions, and presented a basis for future researches on definition teaching in school mathematics.

• Advances in concrete construction
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• 제16권2호
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• pp.79-89
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• 2023

The occurrence of unexpected horizontal offset in the instrument or target will result in accumulated horizontal deviation in segment alignment with traditional short-line match method. A geometry control method, the four-point method, is developed for precast segmental bridges to avoid the influences of unexpected horizontal offset. The concept of the four-point method is elucidated. Furthermore, the detailed instruments and instructions are introduced. Finally, the four-point method is validated through a practical engineering application. According to the survey data, after short-line match precast construction, the vertical deviations on both sides vary between -5 mm and 5 mm in almost all segments, and the horizontal deviations vary between -4 mm and 4 mm in all segments. Without on-site adjustment, the maximum vertical and horizontal closure gaps are 12.3 and 26.1 mm, respectively. The four-point method is suggested to alleviate the issues associated with relatively poor soil conditions in casting yard.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.637-642
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• 2002

Generally, the use of robots in manufacturing industry has been increased during the past decade. GMA(Gas Metal Are) welding is an actively growing area and many new procedures have been developed for use with high strength alloys. One of the basic requirement for welding applications is to study relationships between process parameters and bead geometry. The objective of this paper is to develop a new approach involving the use of neural network and multiple regression methods in the prediction of bead geometry for GMA welding process and to develop an intelligent system that enables the prediction of bead geometry using Rapid Prototyping(RP) in order to employ the robotic GMA welding processes. This system developed using MATLAB/SIMULINK, could be effectively implemented not only for estimating bead geometry, but also employed to monitor and control the bead geometry in real time.