• The Mathematical Education
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• v.47 no.4
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• pp.437-445
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• 2008

On the basis of the meaning and general process of geometric proof through transformation concept and understanding the geometric properties of linear transformation, this study showed that the centroid of geometrical figure and certain properties of a parabola and an ellipse in school mathematics can be explained as a conservative properties through linear transformation. From an educational perspective, this is a good example of showing the process of how several existing individual knowledge can be reorganized by a mathematical concept. Considering the fact that mathematical usefulness of linear transformation can be revealed through an invariable and conservation concept, further discussion is necessary on whether the linear transformation map included in the former curriculum have missed its point.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.787-795
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• 2003

Three types of array antennas are developed for broadcasting band of Koreasat III. First, the specification of the array antenna is decided. Second, characteristics and advantages of three types of antennas using the radial waveguide characteristics is investigated and discussed. Third, design method fur those antenna is studied to meet antenna specifications, and then antennas are designed and tested. Finally, it is concluded that these types of antennas can be efficiently design compared to both parabola antennas and microstrip array within the limited size.

• The Mathematical Education
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• v.53 no.3
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• pp.313-327
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• 2014

'Tangent' is one of the most important concepts in the middle and high school mathematics, especially in dealing with calculus. The concept of tangent in the current textbook consists of the ways which make use of discriminant or differentiation. These ways, however, do not present dynamic view points, that is, the concept of variation. In this paper, after applying 'Roberval's way of finding tangent using vectors in terms of kinematics to parabola, ellipse, circle, hyperbola, cycloid, hypocycloid and epicycloid, we will identify that this is the tangent of those curves. This trial is the educational link of mathematics and physics, and it will also suggest the appropriate example of applying vector. We will also help students to understand the tangent by connecting this method to the existing ones.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.346-351
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• 2000

The study was carried out to investigate the characteristics of vertical velocity distribution measured by current meter at Kangkyung station in Keum river during the period of 1995 to 1997. It suggests the quadratic parabola equation to estimate the vertical velocity profile only from the measurement data of surface velocity. The equation was found to be statistically very stable and showed high significance to express the surface velocity and bottom velocity. The vertical velocity profile was determined by the relationships to the surface velocity, and a coefficient of the quadratic parabola equation. The vertical velocity profile can be applied to calculating the mean velocity and discharge, and to and to analyse the dispersion of pollutant materials in the streamflow.

• The Pure and Applied Mathematics
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• v.22 no.1
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• pp.25-34
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• 2015

In this paper we characterize the isogonal and isotomic conjugates of conic. Every conic can be expressed by a quadratic rational B$\acute{e}$zier curve having control polygon $b_0b_1b_2$ with weight w > 0. We show that the isotomic conjugate of parabola and hyperbola with respect to ${\Delta}b_0b_1b_2$ is ellipse, and that the isotomic conjugate of ellipse with the weight $w={\frac{1}{2}}$ is identical. We also find all cases of the isogonal conjugate of conic with respect to ${\Delta}b_0b_1b_2$. Our characterizations are derived easily due to the expression of conic by the quadratic rational B$\acute{e}$ezier curve in standard form.

• The Mathematical Education
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• v.52 no.1
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• pp.83-95
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• 2013

The purpose of this paper is to explain and reinterprets Apollonius' Symptoms on conic sections based on the current secondary curriculum of mathematics, present the historical background of Apollonius' Symptoms to teachers and students and introduce visualization proof of Apollonius' symptoms on a parabola, a hyperbola and an ellipse by a new method using dynamic geometry software(GSP) respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.334-335
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• 2021

In this paper, the distance traveled by a vehicle in an area where a part of the road is cut is measured using the motion of a parabola. Here, when a car running at a constant speed passes over the edge of a broken road, how far it goes from the edge of the road to fall was calculated.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.1
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• pp.18-25
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• 2003

In this Paper, we propose a dissolve detection method based on video editing model. Our method consists of two steps In the first step, the candidate regions are found by using the first md second derivative of a variance curve. In a variance curve, a dissolve presents a parabola that is downward convex. Therefore the parabola is found as a candidate region for a dissolve. In the second step, the candidate region is verified for a dissolve region. In each candidate region, a variance at a valley of the parabola corresponding to dissolve is estimated and then the candidate region is verified by using estimated valley's variance. The valley's variance is determined by neighbor scene variances, so proposed method is adaptive to detect dissolve with various variances. Experiment results on video of various content types are reported and validated.

• Kyungpook Mathematical Journal
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• v.53 no.1
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• pp.99-104
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• 2013

We study some properties of tangent lines of parabolas. As a result, we establish some characterizations of parabolas.

• Journal of Korean Foot and Ankle Society
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• v.13 no.2
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• pp.218-222
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• 2009

In general, the operative treatment of the brachymetatarsia is the lengthening of the affected metatarsal bone due to the cosmetic problem rather than the functional one. We experienced 22 year-old female bilateral congenital foot deformities such as hallux varus and 1,4th brachymetatarsia treated with reverse Scarf osteotomy on the hallux varus and massive axial metatarsal shortening Weil osteotomy on the 2,3,5th metatarsals which could reconstruct the normal metatarsal parabola.