• Title/Summary/Keyword: two-dimensional shapes

### Analysis for Triangles in Elementary School Curriculum and Textbook: Focusing on the Instructional Teaching and Learning Elements of 2-D Shapes (평면도형의 교수·학습 요소에 따른 삼각형에 관한 초등학교 교과서 분석)

• Kwon, Misun
• Education of Primary School Mathematics
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• v.24 no.4
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• pp.233-246
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• 2021
• Two-dimensional shapes have a great influence on elementary school students' learning and are closely related to other content areas. Therefore, in this study, The Teaching and Learning Elements that should be taught in two-dimensional shapes were extracted from the literature. It also was analyzed that revised mathematics textbooks in the year 2015 were properly implemented with the teaching and learning elements. As a result of the analysis, in the case of Understanding The Concept, the activities in the textbooks are not able to recognize 2-D shapes which are focusing on shapes of the actual object. In the case of Classifying two-dimensional shapes according to the Criteria, the classification criteria were presented differently from what was learned in the previous course. In the aspect of Applying the Concept, the activities in order to Discuss two-dimensional shapes were not sufficient. Lastly, in view of the fact the 2015 revised curriculum is not considered with the relationship between two-dimensional shapes. For that reason, the following Knowing Relationships parts are insufficiently presented; Understanding the Relationship Between shapes through Definitions and Properties, Identifying the relationship between shapes throughout classification activities, and Discussing the relationship between shapes. Based on the analysis result of two-dimensional shapes, it is suggested that the finding of this research helps to enlarge the teaching methodology of triangles and provide educational perspectives for development in other shape areas.

### Effects of Background Depth Information on the Judgment of Two-dimensional Shapes (배경 깊이정보가 이차원 자극의 형태 판단에 미치는 영향)

• Kim, Young-Geun;Shin, Hyun-Jung
• Korean Journal of Cognitive Science
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• v.17 no.4
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• pp.287-301
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• 2006
• Two experiments were performed to investigate effects of background depth information on the judgment of two-dimensional shapes, using the Posner et al.'s(1969) physical match task. In both experiments, the focus was on whether the background depth information affects the decisions of physical shape sameness of two letters or figures presented successively. In Experiment 1, artificially constructed rues of linear perspective and texture gradient were used, whereas cues contained in a real road situation were used in Experiment 2. The results of both experiments showed that the depth cues affect the perception of two-dimensional shapes. That is, when two stimuli of the same physical shape were likely to be perceived differently due to the given depth cues, response accuracies('yet' in this case) decreased and reaction tines of physical match increased. And when two stimuli of the different physical shape were likely to be perceived the same due to the given depth cues, response accuracies('no' in this case) decreased and reaction times of physical match increased likewise. These results wert discussed in terms of some conceptual methodological problems of the previous studies on the shape constancy and the directions of future research.

### The Effects of Cooperative Learning on Children's Understanding of Geometry (협동학습활동이 유아 기하 학습에 미치는 영향)

• Kwon, Young-Re;Lee, Kyung-Jin;Shin, Ok-Ja
• Korean Journal of Child Studies
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• v.32 no.2
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• pp.71-85
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• 2011
• This study was carried out in order to better understand how cooperative learning effects the geometric understanding of young children. The geometry tasks used in the study included the geometric relationship between two dimensional shapes and three dimensional shapes, coordination, symmetry and transformation visualization and spacial reasoning. The subjects were composed of children aged five years and were taken from two kindergartens in a relatively new city close to Seoul. The experimental group of children the comparative learning in geometry. The comparative group of children were enrolled in a kindergarten that uses an the intergrated curriculum. The results indicated that cooperative learning impacted positively on the children's understanding of geometry. The specific results are as follows : The scores that the experimental acquired were higher in terms of p < .001 level. than the scores of the comparative group studying the geometric relationships between two dimensional shapes and three dimensional shapes, coordination, symmetry and transformation visualization & spacial reasoning.

### Simulation of a Rotating Chain with an Absolute Nodal Coordinate Formulation (절대절점좌표를 이용한 회전체인의 시뮬레이션)

• Yoo, Wan-Suk;Dmitrochenko, Oleg;Pogorelov, Dmitry
• Proceedings of the KSME Conference
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• pp.649-654
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• 2004
• A physically simple but mathematically cumbrous problem of rotating heavy chain with one fixed top point is studied. Nonlinear equation of its two-dimensional shapes of relative equilibrium is obtained and solved numerically. A linear case of small displacements is analyzed in terms of Bessel functions. The qualitative and quantitative behavior of the problem is discussed with the help of bifurcation diagram. Dynamics of the two-dimensional model near the equilibrium positions is studied with the help of simulation using the absolute nodal coordinate formulation (ANCF). The equilibriums are found instable, and the reason of instability is explained using a variational principle.

### Analysis of Spray Characteristics in w-shaped Diesel Engine Combustion Chamber with Impingement Lands (충돌부를 갖는 w-형 디젤엔진 연소실의 분무특성분석)

• Park, K.;Park, D.S.;Kim, M.H.
• Journal of ILASS-Korea
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• v.1 no.4
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• pp.40-45
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• 1996
• This Paper addresses to spray characteristics in w-shaped diesel engine combustion chamber which has impingement parts for 4 sprays injected from an injector. The two-dimensional shapes have been chosen to avoid the difficulties for analysing the spray dynamics in the real chamber. The simple shapes are reproduced with same geometries in vertical or horizontal sections through the impingement lands. The spray developments are visualized with a high speed drum camera and shadowgraphy optical system, and the droplet sizes are measured by Malvern system. The detailed discussions m made for the two different combustion chamber shapes, which are new w-shape using spray wall impaction and general w-shape. The results show that the spray characteristics of the new shape are superior to those of the general w-shape.

### Classification of Elderly Women's Foot Type (노년 여성의 발 유형분류)

• Kim, Nam-Soon;Do, Wol-Hee
• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.3
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• pp.305-320
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• 2014
• This study identifies the foot shapes of elderly women by classifying foot type according to the 3D shape of the foot and 2D sole type analyzing individual characteristics. The subjects were 295 elderly women over 60 years of age who live in Gwangju. A foot scanner (K&I Technology $Nexcan^{(R)}$) was used to obtain three-dimensional shapes of feet and a flat bad scanner (HP Scanjet G2410) was used to obtain the two-dimensional shapes of soles. The anthropometric measuring items consisted of 59 items estimated on the right foot of each subject. Data were analyzed by various statistical methods such as factor analysis, ANOVA and cluster analysis using the SPSS 19.0 statistical program. To classify the side type of elderly women's feet, three-dimensional measurement data were analyzed for the 27 measurement items using factor analysis and 6 factors were extracted (inside height and side gradient, ankle thickness, toe height and midfoot size, lateral malleolus height, instep, and heel height and gradient). A cluster analysis resulted in three types: 36.5% belonged to Type 1 (high forefoot and high midfoot), 31.1% belonged to Type 2 (high forefoot and low midfoot), and 32.4% belonged to Type 3 (low forefoot and high midfoot). The distribution was relatively even. For the sole, 8 factors were extracted (ball width and medial foot protrusion, lateral foot protrusion, forefoot and hindfoot length ratio, ball gradient, heel size, toe breadth, lateral ball length, and foot length) and a cluster analysis resulted in three Types (Type H, Type D, and Type A). The largest proportion (42.7%) belonged to Type H, which is the same as the elderly men's case.