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Matrix Presentations af the Teichmuller Space af A Punctured Torus
김홍찬 한국수학교육학회 2004 純粹 및 應用數學 Vol.11 No.1
A punctured torus (1;1) is a building block of oriented surfaces. Thegoal of this paper is to formulate the matrix presentations of elements of the Te-ichmuller space of a punctured torus. LetC be a matrix presentation of the bound-ary component of (1;1). In the level of the matrix groupSL(2;R), we shall showthat the trace ofC is always negative.
Discrete conditions for the holonomy group of a pair of pants
김홍찬 대한수학회 2007 대한수학회지 Vol.44 No.3
A pair of pants Sigma(0,3) is a building block of orientedsurfaces. The purpose of this paper is to determine thediscrete conditions for the holonomy group piof hyperbolic structure of a pair of pants.For this goal, we classify the relationsbetween the locations of principal lines and entries of hyperbolicmatrices in PSL(2,R).In the level of the matrix group SL(2,R), we will showthat the signs of traces of hyperbolic elementsplay a very important role to determinethe discreteness of holonomy group of a pair of pants.
화염 분무 열분해법에 의해 합성된 SnO2 나노입자의 가스 감응 특성
김홍찬,홍성현,신동욱 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.8
SnO2 nanoparticles were synthesized by flame spray pyrolysis, which were directly deposited on Pt interdigitated substrates. Gas sensing performance was evaluated for various gases such as H2, CO,H2S, and NH3, and it was compared with that of commercial SnO2 nanopowder. The synthesis of SnO2nanoparticles was also conducted in various solvents. As a result, the primary particle size was changed with the solvent of precursor solution, and their H2 sensing properties were significantly affected. SnO2 나노입자를 화염 분무 열분해법을 이용하여 합성하였으며, 다공성 SnO2막을 화염 분무 열분해법을 통해 백금 전극이 올려진 기판 위에 직접적으로 증착하였다. 증착된 다공성 SnO2막의 가스 감응 특성을 수소(H2), 일산화탄소(CO), 황화수소(H2S), 암모니아(NH3)와 같은 다양한 가스에 대해 평가하였으며, 상용화 SnO2 나노분말의 가스 감응 특성과 비교하였다. 또한, 전구체 용액의 용매를 변화시켜가며 SnO2 나노입자를 합성하였다. 용매의 변화에 따라 SnO2 나노입자의 입자 크기의 변화를 관찰하였고, 이에 따른 수소 감응 특성의 변화를 관찰하였다.
DISCRETE PRESENTATIONS OF THE HOLONOMY GROUP OF A ONE-HOLED TORUS
김홍찬 한국수학교육학회 2010 純粹 및 應用數學 Vol.17 No.4
A one-holed torus §(1; 1) is a building block of oriented surfaces. In this paper we formulate the matrix presentations of the holonomy group of a one-holed torus §(1; 1) by the gluing method. And we present an algorithm for deciding the discreteness of the holonomy group of §(1; 1).
김홍찬,연규봉,김원종,박철순 한국전자통신연구원 2019 ETRI Journal Vol.41 No.6
We proposed a novel electromagnetic band‐gap (EBG) cell‐embedded antenna structure for reducing the interference that radiates at the antenna edge in wireless access in vehicular environment (WAVE) communication systems for vehicle‐to‐everything communications. To suppress the radiation of surface waves from the ground plane and vehicle, EBG cells were inserted between micropatch arrays. A simulation was also performed to determine the optimum EBG cell structure located above the ground plane in a conformal linear microstrip patch array antenna. The characteristics such as return loss, peak gain, and radiation patterns obtained using the fabricated EBG cell‐embedded antenna were superior to those obtained without the EBG cells. A return loss of 35.14 dB, peak gain of 10.15 dBi at 80°, and improvement of 2.037 dB max at the field of view in the radiation beam patterns were obtained using the proposed WAVE antenna.