• 대한원격탐사학회지
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• 제19권5호
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• pp.363-370
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• 2003

This paper describes a rectification procedure that relies on a polynomial model derived from the imaging geometry without loss of accuracy. By using polynomial model, one can effectively eliminate the iterative process to find an image pixel corresponding to each output grid point. With the imaging geometry and ephemeris data, a geo-location polynomial can be constructed from grid points that are produced by solving three equations simultaneously. And, in order to correct the local distortions induced by the geometry and terrain height, a distortion model has been incorporated in the procedure, which is a function of incidence angle and height at each pixel position. With this function, it is straightforward to calculate the pixel displacement due to distortions and then pixels are assigned to the output grid by re-sampling the displaced pixels. Most of the necessary information for the construction of polynomial model is available in the leader file and some can be derived from others. For validation, sample images of ERS-l PRI and Radarsat-l SGF have been processed by the proposed method and evaluated against ground truth acquired from 1:25,000 topography maps.

• 한국학교수학회논문집
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• 제2권1호
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• pp.121-131
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• 1999

Recently our educational methodologies have been changed to an open, student-centered structure. Mathematics is now learned through experiential interaction and less emphasis is placed on abstract theories. For example, the axioms of the geometry in the middle school curriculum have been expressed by using symbolic letters. Students find these abstractions very difficult and it hinders their ability to grasp the significance of geometrical concepts. In an effort to simplify these abstract concepts and enhance the students interest and ability to learn, the GSP (Geometry Sketchpad) is proving to be a useful and effective tool. First, Second and third grade students have found the GSP to be extremely useful. While the pad has no sound function it still enables the students to freely change diagrams without disrupting the integrity of the program. There is also a running order of instructions at the bottom of the screen to facilitate the step by step understanding of mathematical procedures. This function makes the program ideal for use by teachers, students and even beginners. Anyone experiencing difficulty can get immediate assistance from the guidebook which is located at the back of each program. Allowing individuals to manipulate and actually see the changing deductions and axiom proofs on the computer screen provides them with immediate feedback and reinforcement. It also enhances their overall interest in learning geometry. The use of the GSP is proving to be an innovative and effective tool in facilitating the transition of mathematics into an open, student-centered educational forum.

• 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.

• 대한토목학회논문집
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• 제13권2호
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• pp.161-171
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• 1993

유역순간단위도를 수로기하학적 특성과 사면을 고려하여 유도하였다. 수로기하학적 특성은 Width function으로 정량화되며, 이것은 출구로부터 임의 흐름거리의 유량 분포를 나타낸다. 유역순간단위도의 유도에 사용된 모형은 간단한 확산함수에 의해 수로에 분포된 초기유량을 추적하는 추적요소와 사변에서의 체류시간 밀도함수인 지수분포로 나타내지는 사면요소로 구성하였다. 본 방법의 적용성을 검토하기 위하여 보청천유역, 위천유역에 대해 4개사상의 실측수문량을 이용하여 유역순간단위유량도를 산정하였으며, 산정 결과, 본 연구에서 제안한 방법 을 이용해 유역순간단위유량도를 유도할 수 있음을 확인하였다.

• 한국정밀공학회지
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• 제21권6호
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• pp.145-152
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• 2004

Depth-sensing indentation is wifely used for evaluation of mechanical properties of thin films. It is generally accepted that the most significant source of uncertainty in nanoindentation measurement is the geometry of the indenter tip. Therefore the successful application of the technique requires accurate calibration of the indenter tip geometry. The direct measurement of geometry of a Berkovich indenter was determined using a atomic force microscope. The indentation geometrical calibration of contact area was performed by analyzing the indenter tip profile. The equations of area functions were proposed for nanoscale thin films..

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1090-1095
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• 2008

Track geometry changes by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, which determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from the characteristics of measuring device. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolley. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is EM-120, measures versine with 10m of symmetrical chord length.

• 한국철도학회논문집
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• 제12권4호
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• pp.506-511
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• 2009

본 연구에서는 대차에서 계측한 가속도 데이터를 사용하여 궤도틀림을 식별하기 위한 알고리즘을 제안하였다. 등가 SISO 모델에 의한 정상궤도틀림 상태에서의 대차진동과 궤도틀림과의 주파수영역 전달함수를 정의하고, 이를 역으로 이용하여 대차에서 계측한 가속도 데이터로 궤도틀림을 예측하였다. 예측된 값과 기준값과의 잔차의 분산 비로정의되는 틀림지수를 사용하여 궤도틀림의 이상을 분석하였다. 궤도틀림을 시간에 따라 변하는 변위 경계조건으로 고려하여 3차원 수치예제를 수행하였으며, 제안된 알고리즘의 타당성을 검증하였다.

• 호남수학학술지
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• 제43권3호
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• pp.385-402
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• 2021

The geometry of Poincaré disk itself is interpreted without any mapping to different spaces. Our approach might be one of the shortest and is intended for educational contribution.

• 대한기계학회논문집A
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• 제21권5호
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• pp.727-734
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• 1997

In practice, the design of forging processes is performed based on an experience-oriented technology, that is designer's experience and expensive trial and errors. Using the finite element simulation and the artificial neural network, we propose an optimal die geometry satisfying the design conditions of final product. A three-layer neural network is used and the back propagation algorithm is employed to train the network. An optimal die geometry that satisfied the same between inner extruded rib and outer extruded one is determined by applying the ability of function approximation of neural network. The neural networks may reduce the number of finite element simulation for determine the optimal die geometry of forging products and further they are usefully applied to physical modelling for the forging design.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1647-1652
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• 2008

Track geometry consists of tangent and curved lines, which caused undesirable changes in initial track geometry by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To be able to objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, this method determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from specific property of measuring tool. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolly. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is Trackmaster, measures versine with 2m of chord length.