• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.566-572
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• 2021

A methodology for the identification and coordinates estimation of air cavities under urban ground or sandy soil using its natural poles and natural resonant frequencies is presented. The potential of this methodology was analyzed. Simulation models of PEC (Perfect Electric Conductor)s with various shapes and dimensions were developed using an EM (Electromagnetic) simulator. The Cauchy method was applied to the obtained EM scattering response of various objects from EM simulation models. The natural poles of objects corresponding to its instinct characterization were then extracted. Thus, a library of poles can be generated using their natural poles. The generated library of poles provided the possibility of identifying a target by comparing them with the computed natural poles from a target. The simulation models were made assuming that there is an air cavity under urban ground or sandy soil. The response of the desired target was extracted from the electromagnetic wave scattering data from its simulation model. The coordinates of the target were estimated using the time delay of the impulse response (peak of the impulse response) in the time domain. The MP (Matrix Pencil) method was applied to extract the natural poles of a target. Finally, a 0.2-m-diameter spherical air cavity underground could be estimated by comparing both the pole library of the objects and the calculated natural poles and the natural resonant frequency of the target. The computed location (depth) of a target showed an accuracy of approximately 84 to 93%.

• The Mathematical Education
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• v.38 no.2
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• pp.189-197
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• 1999

Discrete mathematics allows students to examine and explore unique, special problem situations which were not used to solve problems by paper-and-pencil procedures or applying common formulas. The use and integration of accessible computer-related technologies such as 'Mathematics' or 'Maple' software programs enables students to explore problem situation dramatically. This study shows that it is possible to introduce computer-based discrete mathematics focused on the Leslie matrix model as modeling age-specific population growth to high school students.

• Journal of the Korean Mathematical Society
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• v.55 no.3
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• pp.705-717
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• 2018

We construct some infinite series of free and nearly free curves using pencils of conics with a base locus of cardinality at most two. These curves have an interesting topology, e.g. a high degree Alexander polynomial that can be explicitly determined, a Milnor fiber homotopy equivalent to a bouquet of circles, or an irreducible translated component in the characteristic variety of their complement. Monodromy eigenspaces in the first cohomology group of the corresponding Milnor fibers are also described in terms of explicit differential forms.

• Journal of the Korean Institute of Navigation
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• v.22 no.1
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• pp.15-22
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• 1998

In this paper, discontinuity parts in microstrip line with $\lambda$/4 open stub and one in crank type have been anlayzed by using FDTD(Finite-Difference Time-Domain) analysis method. The noise components, in this case, are occred at the discontinuites of the given microstrip lines, the complex poles were extracted by the analysis using GPOF (Generalized Pencil-of Function) method from electric field of time domain. It has, then, been found that the noise level and the noise frequency components included in signal could be derived.

• Proceedings of the Korea Multimedia Society Conference
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• 1998.10a
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• pp.37-41
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• 1998

정보사회의 주 도구인 컴퓨터에서 한글처리의 불완전함으로 인하여 한국인의 사고 체계는 부분적으로 제약을 받고 있다. 이것은 지적 노동 생산성을 저해할 뿐만 아니라 컴퓨터로 표현할 수 없는 글자는 장기적으로 사용이 뜸해져서 결국 사라지게 될 수도 있다. 본 논문은 컴퓨터가 한국인의 사고력을 높여주고 지적 노동 생산성을 극대화할 도구가 될 수 있도록 마치 연필로 글을 쓸 때처럼 자유스럽게 글자를 임의로 조합할 수 있게 하는데 역점을 가지고, 이를 위하여 훈민정음 원리를 적용하여 천지자연의 글자를 표현한다는 원리를 구현함으로써 연필 컴퓨터에 관한 한 가지 구현을 하였다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.393-398
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• 2001

This paper aims to work process of connecting rod die using CAD/CAM/CNC systems. CAD/CAM/CNC systems are consist of CAD(MDT4.0), CAM(Z-MASTER) software and CNC milling machine. CAM software is purpose to G-code generation for CNC programming. Then CAM software and CNC milling machine are connect to RS-232-C cable for data network.

• Journal of the Chungcheong Mathematical Society
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• v.12 no.1
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• pp.147-155
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• 1999

Let {$C_t$} be a pencil of smooth quartics for $t{\neq}0$ degenerating to a plane quartic $C_0$ with an ordinary cusp of multiplicity 3. We compute the stable limit as $t{\rightarrow}0$ of {$C_t$} when the total surface of this family has a triple point at the singular point of $C_0$.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.220-221
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• 1999

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.269-274
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• 1999

This paper aims to DNC application of car fuel tank die working. DNC system is consist of CAD, CAM software and CNC milling machine. CAM software is purpose to G-code generation for CNC programming. Then CAM software and CNC milling machine are connect to RS-232-C cable for networking.

• The Mathematical Education
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• v.39 no.1
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• pp.49-58
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• 2000

The purpose of this study is to investigate how to teach algorithms in mathematics class. Until recently, traditional school mathematics was primarily treated as drill and practice or memorizing of algorithmic skills. In an attempt to shift the focus and energies of mathematics teachers toward problem solving, conceptual understanding and the development of number sense, the recent reform recommendations do-emphasize algorithmic skills, in particular, paper-pencil algorithms. But the development of algorithmic thinking provides the foundation for student's mathematical power and confidence in their ability to do mathematics. Hence, for learning algorithms meaningfully, they should be taught with problem solving and conceptual understanding.