• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1159-1165
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• 2008

In this paper, a single-feed equilateral-triangular microstrip antenna with truncated corners is used for achieving diverse radiation polarization. The proposed antenna is excited by a microstrip line, which is place parallel to an oblique side of the equilateral-triangular patch. Depending on whether the three identically-sized comers of the triangular patch are cut or not, the equilateral-triangular microstrip antenna shows linear polarization(LP) or left-hand circular polarization(LHCP) or Tight-hand circular polarization(RHCP). Based on the equilateral-triangular microstrip antenna with truncated corners, a novel reconfigurable microstrip antenna with switchable polarization sense is also proposed. The proposed reconfigurable antenna has a simple structure, consisting of a corner-truncated triangular patch, a small triangular conductor, and a microstrip line. Using a biased PIN diode between the patch and the small triangular conductor, it can produce LP or RHCP according to bias voltages. From the measured results, low cross polarization level when operated in the linear state and good axial ratio in the circular state are observed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.542-545
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• 2003

An microstrip array antenna is designed based on the Sierpinski equilateral triangular patch. The Sierpinski geometry is composed of 3 equilateral triangular patch and is easy to generate a circular polarization by sequential rotation array techniques. This 1${\times}$3 Sierpinski equilateral triangular patch antenna is extended to 8${\times}$8 array antenna for satellite broadcasting receptions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.196-199
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• 2010

본 연구는 판에 존재하는 유공형상에 따른 응력 집중 해석이다. 일반으로 판은 가공이 쉽고 제작이 편리하여 그 사용이 많다. 이러한 판의 연결에는 원형의 유공을 이용하는 경우가 많고 구조물의 중량감소를 목적으로 유공을 만드는 경우도 있다. 그러나 판에 존재하는 유공의 경우 응력 집중으로 인한 균열생성과 같은 단점을 가진다. 이를 보완하기 위해 유공부의 최적설계 및 응력해석과 같은 많은 연구들이 수행되고 있다. 본 연구에서는 원형, 정사각형과 정삼각형의 유공을 유한 요소 프로그램을 이용하여 시뮬레이션하고 유공형상에 따라 판에 발생하는 응답을 알아보았다. 또한 원형유공의 응답을 기준으로 정사각형과 정삼각형 유공의 모서리의 곡률반경을 변화시켰을 때 발생하는 응답을 비교하였다. 상용 유한 요소 프로그램인 ANSYS/Workbench를 사용하여 인장응력하의 유공판의 응답 해석을 수행하였으며 얻어진 결과를 유공의 형상, 곡률반경의 변화에 따라 분석하였다.

• Journal of Educational Research in Mathematics
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• v.25 no.4
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• pp.675-690
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• 2015

This study explore the features of mathematical tasks as an effective means to foster pre-service primary teachers' mathematical knowledge for teaching and develop mathematical task for pre-service primary teachers. As a result, prospective teachers have while solving a mathematical task, converting a given situation to a mathematical problem, and solve problems through connections with existing knowledge, and experience seeing the existing mathematical concepts from a new perspective. Finally, we discussed the conditions for a suitable mathematical task in teacher education.

• The Journal of the Korea Contents Association
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• v.7 no.7
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• pp.24-30
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• 2007

This paper observed characteristics of a triangular microstrip patch antenna with T-slot. When a narrow horizontal slot or vertical slot is embedded in a triangular microstrip antenna, we investigated variations of dual resonant frequency according to slot lengths and then we could make a triangular microstrip antenna with T-type slot suitable to a very low dielectric substrate. The proposed antennas used a dielectric substrate which has relative dielectric constant ${\epsilon}_r=3.38$ and a height of 8 [mils] (=0.2032mm) and antenna characteristics of horizontal or vertical slot antennas are compared by a ensemble 8.0 simulator. Theoretical and experimental results of manufactured antennas are compared.

• 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.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1992.06a
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• pp.708-711
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• 1992

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1159-1162
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• 2009

브로드캐스팅 프로토콜은 무선 애드 혹 네트워크에서 컨트롤 메시지를 전체 노드에 전송하기 위한 목적으로 널리 사용된다. 전통적인 브로드캐스팅 프로토콜은 모든 노드가 처음 받은 메시지를 재전송 하기 때문에 극심한 중복전송과 충돌문제가 발생한다. 이러한 문제를 해결하기 위해 최근에 효율적으로 재전송노드를 줄이기 위한 브로드캐스팅 기법들이 제안되었지만 여전히 다수의 불필요한 재전송이 발생한다. 제안 기법은 1-홉 이웃노드의 위치정보를 이용하여 전파반경에 내접하는 정삼각형의 꼭짓점을 구하고 각 꼭짓점에 가장 가까운 이웃노드를 재전송노드로 선택한다. 우리는 먼저 재전송 노드를 최소화하기 위한 이상적인 모델을 제시하고 이상적인 모델에 근접하기 위한 방법을 설명한다. 시뮬레이션 결과를 통해 제안 기법이 기존의 효율적인 브로드캐스팅 프로토콜보다 성능이 우수하며 재전송 노드수가 lower bound에 근접하는 것을 보여준다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1090-1099
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• 2004

In this paper a novel design of equilateral-triangular microstrip antenna using PIN diode fur switching the resonant frequency is presented and experimentally studied. The proposed antenna has changed the resonant frequency by length of spur-lines on the patch, and PIN diodes are utilized to switch the spur-line on and off. The shape of the spur-line is changed according to the on and off states of PIN diode and the equilateral triangular microstrip antenna has different resonant frequencies in accordance with them. The resonant frequency is 1.22 GHz with off states since the surface currents flow the periphery of T shape spur-lines, while the resonant frequency is 1.82 GHz with on states since the surface currents are little effect with the conventional equilateral triangular microstrip antenna. The radiation pattern of the proposed antenna has a good linear polarization with the cross polarization of -20 dB both with on and off states.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.83-83
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• 2004