• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.157-158
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• 2014

본 논문에서는 분할 링 공진기(SRR; split-ring resonator)를 이용한 소형 코플래너 도파관(CPW; coplanar waveguide)급전 슬롯 안테나에 대한 설계 방법을 연구하였다. 제안된 슬롯 안테나는 슬롯의 길이를 줄이기 위해 사각형 모양의 SRR 도체가 슬롯 내에 장하되었다. SRR 도체와 슬롯 사이의 간격, SRR 도체의 폭의 변화에 따른 입력 반사계수 특성을 분석하여 최적의 설계 변수를 도출하였다. 2.45 GHz 대역에서 최적화된 소형 슬롯 안테나를 FR4 기판 상에 $36mm{\times}30mm$ 크기로 제작하였다. 제안된 소형 안테나는 기존의 사각형 슬롯 안테나에 비해 안테나의 길이를 14.3%로 줄여 소형화하였다. 실험 결과, 전압 정재파비(VSWR; voltage standing wave) < 2인 대역이 2.4-2.49 GHz으로 2.45 GHz 대역에서 동작하는 것을 확인하였다.

• 한국전자파학회논문지
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• 제19권11호
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• pp.1248-1253
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• 2008

본 논문은 접지가 있는 비대칭 CPW(Coplanar Waveguide) 선로를 conformal mapping 방법을 사용하여 해석하였다. 이 방법으로 선로의 준정전계 특성 파라미터인 특성 임피던스와 유효 유전율을 계산하였다. 계산된 결과는 상용 프로그램인 IE3D의 결과와 기존 실험값과 비교했으며, 거의 일치함을 보였다. 그리고 본 논문에 해석한 접지가 있는 비대칭 CPW(MCS: Micro Coplanr Strip) 선로를 이용하여 스텝 임피던스 저역 필터에 적용하였다. 제작된 스텝 임피던스 저역 필터는 일반 마이크로스트립 선로로 구현된 저역 필터 특성과 비교하였다. 제작된 필터의 실험 결과를 모의실험과 비교하여 잘 일치함을 확인하였다.

• 대한기계학회논문집A
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• 제32권3호
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• pp.267-273
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• 2008

The circular cylinder pipes are used in the many industrial areas. In this paper, the acoustic wave propagation in the pipe containing a gas is researched. First of all, the theory for the coupled acoustic wave propagation in a pipe is investigated. Acoustic wave propagation in pipe can not be occurred independently between the wave of the fluid and the shell. It requires complicated analysis. However, as a special case, the coupled wave in a high density pipe containing a light density medium is corresponded closely to the uncoupled in-vacuo shell waves and to the rigid-walled duct fluid waves. The coincidence frequencies of acoustic and shell modes contribute to the predominant energy transmission. The coincidence frequency means the frequency corresponding to the coincidence of the wavenumber in both acoustic and shell. In this paper, it is assumed that the internal medium is much lighter than the pipe shell. After the uncoupled acoustic wave in the internal medium and uncoupled shell wave are considered, the coincidence frequencies are found. The analysis is successfully confirmed by the verification of the experiment using the real long steel pipe. This work verifies that the coupled wave characteristic of the shell and the fluid is occurred as predominant energy transmission at the coincidence frequencies.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.57-60
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• 2002

In this paper, transmission lines with low and high characteristic impedance (Z$_{0}$) are fabricated and analyzed. The transmission lines are fabricated on the benzo-cyclo-butene (BCB) films of a low dielectric constant. For the low Z$_{0}$, two types of coplanar waveguide (CPW) structures are fabricated, which include bottom-ground and double-ground type. Measurement shows that Z$_{0}$ values for each CPW type are 7.3 and 9.4$\Omega$, respectively, at a signal line width of 100 #m. Whit the ratio between the spacing of bottom-ground and the signal line with becomes greater than 2.5, the Z$_{0}$ is nearly saturated. In addition, thin film microstrip lines fabricated using the BCB insertion layers show very low Z$_{0}$ of 25.5$\Omega$, and this impedance is ~64 % of the values obtained from the BCB-based CPW structures of the same line width. Measurement result of CPW on BCB layer is 100.5 Ω.s 100.5 Ω.

• 전기학회논문지
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• 제56권12호
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• pp.2196-2201
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• 2007

Materials used at microwave are usually used as a dielectric with a manufacturing purpose of printed circuit boards, etc. Complex permittivity of them can be measured from attenuation constant or propagation constant of a transmission line using a microstrip line with bulk type. But as the technique recently which can manufacture to have complex permittivity and permeability demanded using nonferrous metals for powder-type grows up, we need sensors and methods which can measure characteristics of powder-type materials. So far measuring methods of permittivity and permeability with waveguide or coaxial cable are used but they have faults which have a complex measurement method and are difficult to simultaneously measure permittivity and permeability. In this paper, a simultaneous measuring method of permittivity and permeability with 2-port coaxial cable and a new proposed calculation. The proposed 2-port coaxial cable is designed to be easy to insert materials and to have a wideband. We measure permittivity and permeability of magnetic powder(Ni-Fe-Mo, Ni-Fe) which reveal its characteristic at $0.3{\sim}1.3GHz$ to identify the proposed sensor.

• 한국항행학회논문지
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• 제10권4호
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• pp.326-332
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• 2006

본 논문에서는 수직편파 수평면내 무지향성을 갖는 마이크로스트립 안테나를 연구하기 위하여 마이크로스트립 패치의 안테나 소자 4개를 원통형 표면상에 수평으로 배열하였다. 안테나의 중심주파수는 ISM 대역인 2.45GHz를 선택하였다. 이는 무선 LAN의 접속점, 무선 마이크의 기지국 등에서 적용이 가능하기 때문이다. 먼저 기본 계산식에서 기본 패치의 폭과 길이를 계산하고 2.5D와 3D 컴퓨터 시뮬레이션으로 최적화하였다. 제작된 안테나의 특성을 측정한 결과 동축케이블 포트의 임피던스는 51.915+j3.688 ${\Omega}$이며, 반사손실은 -31dB, 전압정재파비는 1.081로 나타났다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.564-566
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• 2012

본 논문에서는 코프래너 도파관으로 급전되는 소형 광대역 평면 모노폴 안테나의 설계방법에 대해 연구하였다. 제안된 구조의 광대역 모노폴을 지상파 디지털방송 수신용으로 최적화 설계하였다. 광대역 모노폴은 특성 임피던스 75옴의 코프래너 도파관으로 급전되고 $100mm{\times}200mm$ 크기의 FR4 기판에 설계하였다. 모노폴을 소형화 하기 위해 슬릿을 부가하고 급전선과 모노폴의 임피던스 정합을 위해 유도성 스터브를 장하하였다. 디지털 방송 주파수 대역인 470-806 MHz 대역에서 동작하도록 설계된 안테나를 FR4 기판 상에 제작 후 실험을 통하여 연구결과의 타당성을 검증하였다.

• 한국통신학회논문지
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• 제19권9호
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• pp.1782-1792
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• 1994

$Ti:LiNbO_3$채널형 광도파로와 Asymmetric Coplanar Strip(ACPS) 전극구조를 이용해서, $1.3{\mu}m$에서 동작하는 진형파형 위상 광변조기를 설계, 제작한 다음 변조특성을 관찰하였다. 위상정합이 개선되도록 ACPS 진행파형 전극을 설계하기 위해서 전극과 완충박막의 두께를 포함하여, 전극제원의 해석적 함수로 특성저항, 변조파의 유효굴절률 및 전극손실 등을 고려하였다. Ti 확산방법으로 저손실 채널형 광도파로 제작하였으며, double-spin image reversal 공정을 이용해서 $2.5{\mu}m$ 두께의 전극을 형성하였다. 9GHz 부근에서의 전극구조 공진형상 때문에 변조특성이 제한 되었지만, 2.5GHz 까지는 큰 왜곡없이 변조특성이 관찰되었다.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.220-226
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• 2011

We have proposed a new method to accurately predict the resonance of Fabry-Perot Cavity (FPC) antennas enclosed with conducting side walls. When lateral directions of an FPC antenna are not blocked with metallic walls, the conventional technique is accurate enough to predict the resonance of the FPC antenna. However, when the FPC antenna has side walls, especially for case with only a short distance between the walls, the conventional prediction method yields an inaccurate result, inevitably requiring a tedious, time-consuming tuning process to determine the correct resonant height to provide the maximum antenna gain in a target frequency band using three-dimensional full-wave computer simulations. To solve that problem, we have proposed a new resonance prediction method to provide a more accurate resonant height calculation of FPC antennas by using the well-known resonance behavior of a rectangular resonant cavity. For a more physically insightful explanation of the new prediction formula, we have reinvestigated our proposal using a wave propagation characteristic in a hollow rectangular waveguide, which clearly confirms our approach. By applying the proposed technique to an FPC antenna covered with a partially reflecting superstrate consisting of continuously tapered meander loops, we have proved that our method is very accurate and readily applicable to various types of FPC antennas with lateral walls. Experimental result confirms the validness of our approach.

• Smart Structures and Systems
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• 제18권3호
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• pp.471-484
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• 2016

Optical fiber sensors have been proven that they have the potential to detect high-frequency ultrasonic signals, in structural health monitoring field which generally refers to acoustic emission signals from active structural damages and guided waves excited by ultrasonic actuators and propagating in waveguide. In this work, the sensing properties of optical fiber sensors based on Mach-Zehnder interferometer were investigated in the metal plate. Analytical formulas were conducted first to explore the parameters affecting its sensing performances. Due to the simple and definable frequency component, the Lamb wave excited by the piezoelectric wafer was employed to study the sensitivity of the proposed optical fiber sensors with respect to the frequency, rather than the acoustic emission signals. In the experiments, according to above investigations, spiral shape optical fiber sensors with different size were selected to increase their sensitivity. Lamb waves were excited by a circular piezoelectric wafer, while another piezoelectric wafer was used to compare their voltage responses. Furthermore, by changing the excitation frequency, the tuning frequency characteristic of the proposed optical fiber sensor was also investigated experimentally.