• 대한수학교육학회지:수학교육학연구
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• 제10권1호
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• pp.139-159
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• 2000

The experimental software such as Cabri II, The Geometer's Sketchpad, etc. provides dynamic environment which construct and explore geometric objects interactively and inductively. It has the effects on mathematics itself differently from other technologies that are used in instruction. What is its characteristics\ulcorner What are the educational implication of it for the learning of geometry\ulcorner How is mental reasoning of geometric problems changed by transformation of the means of representation and the environment to manipulate them\ulcorner In this study, we answer these questions through the review of the related literatures and the analysis of textbooks, teaching materials using it and curricular materials. Also, we identify implications about how the criteria for choosing geometic content and the ways of constructing context, for orchestrating the students' exploration with the secondary geometry curriculum, can be changed.

• Advances in Computational Design
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• 제4권4호
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• pp.397-413
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• 2019

In this paper, static nonlinear analysis of gable frame is performed using OpenSees software. Both geometric and material nonlinearities are considered in analyses. To consider large displacements, co-rotational coordinate transformation is used in software. The effects of symmetric and asymmetric support conditions including clamped and simple supports are studied. On the other hand, the material nonlinearity is reflected on analyses using Giuffre-Menegotto-Pinto steel material. Note that strain hardening characteristics are also considered in this model. Moreover, I-shaped cross-section is assumed for all members. The results are provided for different geometry properties of gable frame including shallow and deep inclined roof. It should be added that buckling and post-buckling behaviors of gable frame are investigated using related equilibrium paths. A comparison study is also implemented on the responses of buckling loads obtained for different support and geometry conditions. To trace snap-through paths completely, a displacement control method entitled arc-length is utilized. Findings show the capability of proposed model in nonlinear analysis of gable frames.

• 대한수학교육학회지:학교수학
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• 제4권1호
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• pp.15-27
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• 2002

The purpose of this thesis is, through analysing the characteristics of the definitions in Korean school mathematics textbooks, to explore the levels of them. Definitions use din 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. We tried to construct, with consideration about methods of definition, frame for analysing the types of the definitions in school mathematics. 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. 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 let·els 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.

• 제어로봇시스템학회논문지
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• 제13권12호
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• pp.1222-1229
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• 2007

In this paper, we propose a new obstacle negotiation method for the rescue robot. The rescue robot has a variable geometry single-tracked mechanism, so it can maximize a contact length with ground for the adaptability to off-road and pursue a stable system due to the lower center of gravity. In this research, we add the basis of autonomous navigation, driving mode control based on obstacle detection, to the robot to realize automation of mode transformation. Obstacle detection using PSD(Position Sensitive Device) infrared sensors gives active transformation of the track shape. Finally, experimental results about mentioned are presented.

• 한국측량학회지
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• 제28권2호
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• pp.281-287
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• 2010

본 연구에서는 지상레이저스캔 데이터의 보정을 위하여 변환 알고리즘을 비교하였다. 두 개 이상의 시점으로부터 취득된 스캔 데이터를 변환하는 데 많이 사용되는 pair-wise 변환은 오차가 누적된다. 스캔데이터간 보정에 많이 사용되는 ICP 알고리즘은 초기 기하정보가 필요하며, 여러 스캔데이터를 보정할 때 많은 기준점으로 인하여 동시에 보정하기 어렵다. 따라서 정합점을 이용한 글로벌 보정 방법을 수행하였다. 정합점은 SIFT를 이용하여 자동으로 강도영상으로부터 추출하였으며, GP 분석을 이용하여 글로벌 보정을 수행하였다. 제안된 글로벌 보정 방법은 연산속도, 정확도, 자동화 등에 있어서 장점을 지닌 것으로 나타났다. 본 연구의 성과를 이용하여 정합문제에 있어서 정확도와 속도를 적절히 고려한 보정방법을 개발할 수 있다.

• 한국광학회지
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• 제32권6호
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• pp.276-285
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• 2021

본 논문은 디스플레이용 OLED의 제작 공정에 사용하는 레이저 박리(laser lift-off, LLO) 장비의 선형빔 광학계에 대한 연구로서, M²가 큰 레이저를 사용하는 경우, 단축의 선폭을 작게 만들면서 공정심도를 깊게 유지하기 위한 빔 변환 모듈(beam transformation unit, BTU)을 포함한 광학계에 대한 연구를 진행하였고, 단축 형상을 슈퍼 가우시안으로 만들 수 있는 방법과 flat-top 분포로 만들 수 있는 광섬유를 사용하는 빔 변환 방식에 대하여 제시하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.317-324
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• 1999

The present work is an attempt to calculate the steady state pressure and perturbed pressure of herringbone grooved journal bearings. A generalized coordinate system is introduced to handle the complex bearing geometry. The coordinates are fitted to the groove boundary and the Reynold's equation is transformed to be fitted to this coordinates system using the Gauss divergence theorem. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The characteristics of finite herringbone grooved journal are well calculated using this method.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제12권4호
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• pp.271-281
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• 2008

Quarter a century ago, I founded the Colorado Mathematical Olympiad. The Colorado Mathematical Olympiad is the largest essay-type in-person mathematical competition in the United States, with 600 to 1,000 participants competing annually for prizes. In this article, I explain what it is, how it works, give examples of problems and solutions, and share with the reader careers of some of the Olympiad's winners.

• Tribology and Lubricants
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• 제16권6호
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• pp.432-439
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• 2000

The present work is an attempt to calculate the steady state pressure and perturbed pressure of herringbone grooved journal bearings. A generalized coordinate system is introduced to handle the complex bearing geometry. The coordinates are fitted to the groove boundary and the Reynold's equation is transformed to be fitted to this coordinate system using the Gauss divergence theorem. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The caharacteristics of finite herringbone groove journal bearing are well calculated using this method.

• 산업공학
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• 제9권2호
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• pp.129-141
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• 1996

Recently, the tire mold of a passenger car is made almost via aluminum casting, and it is necessary to prepare a master model of the tire for the casting. Because of the geometrical feature of tire, as well known, the master model must be machined by a 5-axis NC machine. The paper proposes a procedure to model and machine the master model. The approach includes (a) transformation of 2D drawing of tire into 3D geometry, (b) modeling surfaces of tire, and (c) inverse kinematics of a 5-axis NC machine. An implementation of the proposed procedure is also presented.