• Title/Summary/Keyword: solid figures

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An Analysis on the Concept and Measuring Activities of the Height of Figures in Elementary School Mathematics Textbooks2 (초등학교 수학 교과서에 서술된 높이 개념과 측정 활동 분석)

  • Paek, Dae Hyun
    • Education of Primary School Mathematics
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    • v.19 no.2
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    • pp.113-125
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    • 2016
  • The concept and measuring activities of the height of figures are essential to find the areas or volumes of the corresponding figures. For plane figures, the height of a triangle is defined to be the line segment from a vertex that is perpendicular to the opposite side of the triangle, whereas the height of a parallelogram(trapezoid) is defined to be the distance between two parallel sides. For the solid figures, the height of a prism is defined to be the distance of two parallel bases, whereas the height of a pyramid is defined to be the perpendicular distance from the apex to the base. In addition, the height of a cone is defined to be the length of the line segment from the apex that is perpendicular to the base and the height of a cylinder is defined to be the length of the line segment that is perpendicular to two parallel bases. In this study, we discuss some pedagogical problems on the concepts and measuring activities of the height of figures to provide alternative activities and suggest their educational implications from a teaching and learning point of view.

Analysis of the definition and visual representation of the prisms and pyramids (각기둥과 각뿔의 정의 및 시각적 표현에 대한 분석)

  • Kang, Yunji
    • Education of Primary School Mathematics
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    • v.27 no.2
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    • pp.139-153
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    • 2024
  • This analysis was intended to present pedagogical implications related to the guidance of solid figures in elementary mathematics textbooks. The definitions of mathematical concepts and visually represented examples presented in the prism and pyramid units were analyzed. As a result of the analysis, differences were observed in both the method and content of defining mathematical concepts, even though the same curriculum was reflected. Additionally, various forms of visual examples were provided during the learning process of prisms and pyramids. Based on the results of this analysis, it is necessary to understand the definition of mathematical concepts and to teach students in an appropriate manner, considering the goals of each session and the objectives of the activities involved in presenting visual examples.

Internal Ballistic Analysis using Two Kinds of Propellant for Design of Dual-thrust Solid Rocket Motor (이중추력형 고체 추진기관 설계를 위한 이종추진제 적용 내탄도 해석)

  • Kim, Hanjun;Moon, Kyungje
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.1176-1179
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    • 2017
  • In this study, internal ballistic analysis theories of dual-thrust solid rocket motor using two kinds of propellant are found, and the theories are applied to develop internal ballistic analysis model. Internal ballistic analysis which is dual-thrust solid rocket motor using two kinds of propellant is carried out an applying of the random figures of two kinds of propellant and an analyze of the test results. Through this analytical model was able to an applying internal ballistic analysis for dual-thrust solid rocket motor using two kinds of propellant.

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A Study on the Construction of Regular Polygons in 'Method of Ruler and Compass' (`자와 컴퍼스의 방법`에 제시된 정다각형의 작도 방법 연구)

  • Han, In-Ki
    • Journal for History of Mathematics
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    • v.21 no.2
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    • pp.119-134
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    • 2008
  • In this paper we study a book 'Method of Ruler and Compass' written in Russia three hundreds years ago. In this book many construction problems related with plane figures and solid figures are solved. In this study we analyze construction method of some regular polygon(square, regular pentagon, regular octagon, regular decagon) suggested in 'Method of Ruler and Compass', give mathematical proofs of these construction.

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An Effect of Students' Learning for Spatial Ability Using a Geometric Manipulative (교구를 활용한 중학교 공간능력 향상을 위한 수업에서 학습의 효과)

  • Choi-Koh, Sang-Sook;Jung, In-Chul;Park, Man-Goo
    • The Mathematical Education
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    • v.48 no.1
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    • pp.1-20
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    • 2009
  • The study was to investigate an effect of students' learning for enhancing spatial ability, using a geometric manipulative recently designed. A mixed methodology was chosen to achieve the purpose of the study. To find students' achievement, 152 of the 8th graders in Kyunggi Do participated in data collection. At the same time. students' performance of the class was videotaped and analyzed to see students' responses, The results showed that the effect of using the manipulative was statistically significant at level, p<.05 to enhance the spatial ability. Specifically, in comparison of each component. spatial orientation was more effective than spatial visualization. In the spatial orientation, the part of field was more effective than the reorganized whole. It showed that students were given more opportunities to find mathematical properties and relations between 2nd and 3rd-dimensional figures through their intuitive observation, and also the manipulative helped the students find the property of the part of field because it gave an easy way to manipulate the property of the find parts of whole which was composed of the frame of the solid figures without surfaces. In using the manipulative, students were very flexible in finding the number of plane figures, but the relations between the 2nd and 3rd dimensional figures need to be clearly guided in consideration of the characteristics of the manipulative, based on the definitions of geometric properties(cf. points can make lines, not surfaces directly).

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The Changes of Benzo[α]pyrene in Herbal Teas containing Astragalus membranaceus, Schizandra chinensis, Liriope platyphylla and Platycodon grandiflorum Which are affected by the Puffing Conditions (Puffing 조건에 따른 황기, 오미자, 맥문동 및 길경을 첨가한 한방차의 Benzo[α]pyrene 변화)

  • Oh, Sung-Cheon
    • The Korean Journal of Food And Nutrition
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    • v.27 no.1
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    • pp.75-79
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    • 2014
  • The following study is the result of herbal teas puffed at different temperatures between $140{\sim}220^{\circ}C$. Depending on treatment temperatures, the water contents decreased, while some carbonization occurred and crude ash contents relatively increased. Also, the crude protein and crude fat experienced little changes. B(${\alpha}$)P contents (0.16~0.17 ppb) showed little change according to treatment temperatures. From this result, the B(${\alpha}$)P content differed depending on the treatment temperature and raw materials. Solid elution rate figures of the herbal teas ranged from 0.27~0.45% (w/w) and the rate of solid elution increased along with higher puffing temperatures. The reason for the increase in solid elution rates is due to the breakage of cross bridges between the raw materials in the herbal tea which are carbohydrates, proteins, lipids and etc. after treatments of physical changes rather than chemical ones.

Development of Measurement mechanism of Laser Beam Spot size for Industrial SFF system (산업용 SFF 시스템에서 Laser Beam Spot size 측정 메커니즘 개발)

  • Bae, Sung-Woo;Kim, Dong-Soo;Choi, Kyung-Hyun
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1383-1388
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    • 2007
  • Accuracy and processing time are very important factors when the desired shape is fabricated with Selective Laser Sintering (SLS), one of Solid Freeform Fabrication (SFF) systems. In a conventional SLS process, laser spot size is fixed during laser exposing on the sliced figure. Therefore, it is difficult to accurately and rapidly fabricate the desired shape. In this paper, to deal with those problems an SFF system having ability of changing spot size is developed. The system provides high accuracy and optimal processing time. Specifically, a variable beam expander is employed to adjust spot size for different figures on a sliced shape. Finally, Design and performance estimation of the SFF system employing a variable beam expander are achieved and the mechanism will be addressed to measure the real spot size generated from the variable beam expander.

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Histopathology of canine basal cell tumor (개에서 발생한 기저세포종양에 관한 병리조직학적 연구)

  • Bak, Eun-jung;Chae, Chan-hee
    • Korean Journal of Veterinary Research
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    • v.35 no.2
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    • pp.361-368
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    • 1995
  • Basal cell tumors from 53 dogs were examined histologically and classified as basal cell adenoma(n=44), granular basal cell adenoma(n=1), basal cell carcinoma(n=3), basosquamous cell adenoma(n=1), basosquamous carcinoma(n=4) on the basis of malignancy and squamous metaplasia. Female was twenty three and male was thirty. Affected dogs are usually 5.6 years and sex predilection have not been seen. None of tumor examined was metastasized into other organs. Distinct patterns identified in the basal cell adenoma are solid(n=15), cystic(n=13), adenoid(n=8), medusa(n=5) and ribbon(n=3). Solid basal cell adenoma is common type in benign basal cell adenoma. Only one neoplasm was granular basal cell adenoma which was characterized by eccentric nucleus and abundant granular cytoplasm. Basal cell carcinoma showed anaplastic appearance histologically and had atypical basaloid epithelial cells and multinucleated giant cells with moderate number of mitotic figures. Both basosquamous cell adenoma and carcinoma had squamous metaplasia.

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A modified couple-stress magneto-thermoelastic solid with microtemperatures and gravity field

  • Samia M. Said;Elsayed M. Abd-Elaziz;Mohamed I.A. Othman
    • Structural Engineering and Mechanics
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    • v.87 no.5
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    • pp.475-485
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    • 2023
  • The present study deals with wave propagation in a modified couple-stress generalized thermoelastic solid under the effect of gravity and magnetic field. The problem is solved by a refined microtemperatures multi-phase-lags thermoelastic theory. The Fourier series and Laplace transforms will be used to obtain the general solution for any set of boundary conditions. Some comparisons have been shown in figures to estimate the effects of the gravity field, the magnetic field, and different theories of thermoelasticity in the presence of the hall current effect on all the physical quantities. Some particular cases of special interest have been deduced from the present investigation.

Pyroelectric Peyformance Evaluation of Pure PZT and Alternately Deposited PZT/PT Thin Films (PZT 순수박막과 PZT/PT 교차박막의 적외선 감지 특성 비교)

  • Ko, Jong-Soo;Kwak, Byung-Man
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.6
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    • pp.1001-1007
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    • 2002
  • To improve the performance of the PZT thin flms, each PZT and PT layer was alternately deposited on a Pt/Ti/Si$_3$N$_4$/SiO$_2$/Si substrate by a modified sol-gel solid precursor technique. For comparison, PZT thin films were also prepared with an identical method under the same conditions. XRD measurement revealed that the diffraction pattern of the multilayer film was due to the superimposition of the PZT and PT patterns. At 1㎑, a dielectric constant of 389 and 558, a dielectric loss of 1.2% and 1.1% were obtained for the PZT/PT and PZT thin films, respectively. If we consider the PT dielectric constant to be 260, it is clear that the dielectric constant of alternately deposited PZT/PT thin films was well adjusted. The PZT/PT thin film showed a low dielectric constant and a similar dielectric loss compared with those of the PZT film. The figures of merit on detectivity for the PZT/PT and PZT thin films were 20.3$\times$10$\^$-6/㎩$\^$-$\sfrac{1}{2}$/, and 18.7$\times$10$\^$-6/㎩$\^$-$\sfrac{1}{2}$/, and the figures of merit on voltage response were 0.038㎡/C and 0.028 ㎡/C, respectively. The high figures of merit for the PZT/PT film were ascribed to its relatively low dielectric constant when compared to the PZT thin films.