• Human Ecology Research
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• 제55권2호
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• pp.125-140
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• 2017

This study composed spatial cognition tasks within the system of geometric area to study children's spatial cognition development systematically. It surveyed children's execution of direction, rotation, symmetry, conjugation, and part/whole cognition tasks. A spatial geometry cognition task set (consisting of total 27 sub-tasks) was presented to 60 children (20 each in groups of 3-, 4-, and 5-year-old) in order to confirm how children's execution of spatial geometry cognition changed depending on children's age and sex as well as if the execution of the spatial geometry cognition showed a difference after each task area. As a result, the execution of the whole direction task and the part/whole task gradually increased between age 3 and age 5. The execution of the whole rotation task, whole symmetry task, and whole conjugation task rapidly increased between age 3 and age 4. Significant sexual difference did not appear in the execution of spatial geometry cognition tasks. The execution of the conjugation and part/whole task was high in each task area, and the execution of the direction, rotation, and symmetry task was relatively low. In addition, the difference of task execution appeared in the sub-tasks of direction, symmetry, and conjugation areas. This result suggests the theoretical discussion possibility of children's spatial geometry cognition development. In addition, the empirical results of this study can be applied to child education plans and activity compositions appropriate for child development.

• International Journal of CAD/CAM
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• 제3권1_2호
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• pp.13-17
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• 2003

Hybrid method of representing geometric entities as combination of boundary (B-rep) and functional (F-rep) representations is presented which can be used as a basis of solid modeling kernel. It contains whole functionality of classic B-rep kernel, and also supports enveloping (sweep of solid body). Principles and keysolutions are considered. Example of a real task that comes from gearing is provided.

• 제어로봇시스템학회논문지
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• 제4권1호
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• pp.105-112
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• 1998

Regarding the measure of dexterity of robot manipulators, two geometric tools, manipulability ellipsoids and manipulability polytopes, are examined and compared with each other. Even though the manipulability ellipsoid approach is the most widely used technique, it is shown that the manipulability ellipsoid transforms the inexact joint velocity constraints into task space and so it may fail to give an exact measure of dexterity and optimal direction of motion in task space. After showing that the polytope approach can handle such problems, we propose a practical polytope method which can be applied to 3-dimensional task space in general. The relation between manipulability ellipsoids and manipulability polytopes are also explored for a redundant case and a non-redundant one.

• 대한인간공학회지
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• 제8권2호
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• pp.19-26
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• 1989

This study, as a part of integrated human-robot ergonomics, improves the robot motion control on the robot task in the TOES/WCS whose purpose is improving the teaching task constructed in the previous study. First, the updated combined fuzzy process using a new membership function with Weber's law is constructed for the purpose of coordinate reading of the end points in the macro motion control. Second, an algorithm using the geometric analysis is desinged in order to calculate position values and posture values of the robot joints. Third, the MGSLM method is designed to remove unnecessary the robot motion control caused by the GSLM method in the micro motion control. Consequently, proposed methods in this study lessen burdcn of a human of an improvement of the robot motion control and reduce the teaching time of a human operator and inaccuracy of the teaching task, which contribute to the integrated human-robot ergonomics.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제25권3호
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• pp.201-225
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• 2022

This paper details case study vignettes that focus on enhancing the teaching and learning of geometry and measurement in the elementary grades with attention to pedagogical practices for teaching through problem solving with rigor and centering equitable teaching practices. Rigor is a matter of equity and opportunity (Dana Center, 2019). Rigor matters for each and every student and yet research indicates historically disadvantaged and underserved groups have more of an opportunity gap when it comes to rigorous mathematics instruction (NCTM, 2020). Along with providing a conceptual framework that focuses on the importance of equitable instruction, our study unpacks ways teachers can leverage their deep understanding of geometry and measurement learning trajectories to amplify the mathematics through rigorous problems using multiple approaches including learning by doing, challenged-based and mathematical modeling instruction. Through these vignettes, we provide examples of tasks taught through rigorous problem solving approaches that support conceptual teaching and learning of geometry and measurement. Specifically, each of the three vignettes presented includes a task that was implemented in an elementary classroom and a vertically articulated task that engaged teachers in a professional learning workshop. By beginning with elementary tasks to more sophisticated concepts in higher grades, we demonstrate how vertically articulating a deeper understanding of the learning trajectory in geometric thinking can add to the rigor of the mathematics.

• Journal of Information Processing Systems
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• 제10권4호
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• pp.503-522
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• 2014

In the cursive handwriting recognition process, script trajectory segmentation and modeling represent an important task for large or open lexicon context that becomes more complicated in multi-writer applications. In this paper, we will present a developed system of Arabic online handwriting modeling based on graphemes segmentation and the extraction of its geometric features. The main contribution consists of adapting the Fourier descriptors to model the open trajectory of the segmented graphemes. To segment the trajectory of the handwriting, the system proceeds by first detecting its baseline by checking combined geometric and logic conditions. Then, the detected baseline is used as a topologic reference for the extraction of particular points that delimit the graphemes' trajectories. Each segmented grapheme is then represented by a set of relevant geometric features that include the vector of the Fourier descriptors for trajectory shape modeling, normalized metric parameters that model the grapheme dimensions, its position in respect to the baseline, and codes for the description of its associated diacritics.

• 대한전자공학회논문지SP
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• 제46권4호
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• pp.124-131
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• 2009

방사선영상의 신뢰할 만한 영역검출은 용접부위 결함탐지 이전의 중요한 작업 중의 하나이다. 추출되는 특징들은 각 분할된 영상에 대하여 서로 다른 군집으로 분류되어야한다. 그러나 종래의 분할 기법으로는 방사선영상 고유의 색도중첩과 낮은 SN비로 인해 만족할 만한 결과를 얻기가 쉽지 않다. 전체나 국부처리로는 잡음제거에 취약할 뿐만 아니라 영역분류도 어렵다. 이 논문은 산업용 CR 영상에서 영역기반실현의 분할을 위한 적절한 기법을 제시한다. 강판튜브에서 용접과 비용접 구간의 기하학적 차이가 영상화 과정을 통해 배경부, 두께부, 중간부 및 용접부 영역을 생성하고 계층 구조적 배열을 형성한다. 비록 그 구조가 잡음에 훼손되기는 하지만 영역구분 구도 각 영역의 차별된 기하학적 특성에 근거한 국부군집화에 의해 선별이 가능하다. 관련 영역의 기하학적 속성에 의해 그에 따른 영역이 계층별로 선별되어 실제 구분이 영역간 경계를 반영하기 때문에 직경과 길이방향의 군집화는 각 계층의 구별을 명확케 한다. 그리고 산업용 강판튜브 CR영상에 다양한 분할 방식으로 비교 실험을 실시하여 이 기법의 효과를 보였다.

• 한국초등수학교육학회지
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• 제21권2호
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• pp.309-341
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• 2017

본 연구에서는 초등학교 학생들의 백분율 이해에 대한 실태를 조사하고 이를 기초로 백분율 지도를 위한 시사점을 제공하고자 하였다. 이를 위해 부분 전체 과제, 변화 과제, 비교 과제로 구분한 16개의 문항으로 구성된 검사도구를 개발하고, 백분율을 학습한 초등학교 6학년 학생 182명을 대상으로 검사를 실시하여 각 문항의 정답률 및 학생들이 사용한 전략, 오류 유형을 분석하였다. 분석 결과 백분율 과제에 대한 정답률이 전반적으로 낮았고, 과제 유형별로는 부분 전체 과제의 정답률이 비교 과제와 변화 과제보다는 높았으며, 백분율 계산 전략은 형식적 동치 소수 전략뿐만 아니라 비형식적 전략도 많이 사용하였고, 다양한 오류 유형이 나타났다. 연구 결과를 바탕으로 백분율 지도를 위한 시사점으로 백분율의 의미 강조, 다양한 비교 과제와 변화 과제의 포함, 비형식적 전략의 강조와 모델의 사용, 다양한 백분율 상황에서 결과량, 백분율, 기준량 사이의 관계 파악을 제안하였다.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제4권2호
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• pp.63-77
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• 2000

The purpose of this article is to devise the activities based on van Hiele levels of geometric thought using computer software, Geometer\\\\`s Sketchpad(GSP) as a tool. The most challenging task facing teachers of geometry is the development of student facility for understanding geometric concepts and properties. The National Council of teachers of Mathematics(Curriculum and Evaluation Standards for School Mathematics, 1991; Principles and Standards for School Mathematics, 2000) and the National Re-search Council(Hill, Griffiths, Bucy, et al., Everybody Counts, 1989) have supported the development of exploring and conjecturing ability for helping students to have mathematical power. The examples of the activities built is GSP for students ar designed to illustrate the ways in which van Hiele\\\\`s model can be implemented into classroom practice.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.492-495
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• 1997

This paper aims to derive a mathematical model of the dynamics of handling task in field robot which stable grasping and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraints of tight area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Thirdly, simulation results are shown and the effects of geometric constraints of contact-area are discussed. Finally, it is shown that even in the simplest case of dual single D.O.F. manipulators there exists a sensory feedback from sensing data of he rotational angle of the object to command inputs to joint actuators and this feedback connection from sensing to action eventually realizes secure grasping of the object, provided that he object is of rectangular shape and motion is confined to a horizontal