• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.263-267
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• 2009

Cylindrical monopole antenna is one of most promising candidates for multi-band applications such as PCS, WLAN, DMB, and UWB wireless services. In this research, we demonstrate that there exist two types of current distributions according to the exciting frequency in a double band cylindrical monopole antenna, in which double resonance is achieved by adjusting the coupling structure of the antenna base. The operating modes of current distributions are identified from CST software simulations, the standing wave mode in a lower band and the traveling wave mode in a higher band. Also it is noticed that the mode behavior is quite similar to a helical antenna, a standing-wave (resonance) mode and a traveling-wave (non-resonance) mode according to the electrical dimensions of antenna. The effective ranges for operating modes and design formulas of the double band antenna are derived from simulation and measured results.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.135-138
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• 2009

Cylindrical monopole antenna is one of most promising candidates for multi-band applications such as PCS, WLAN, DMB, and UWB wireless services. In this research, we analyze the current distributions of operating modes for a cylindrical double-resonant monopole antenna. Two modes, the standing wave mode in a lower band and the traveling wave mode in a higher band, are identified from CST software simulations. Finally, design formulas are derived form the simulation results.

• Journal of applied mathematics & informatics
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• 제30권3_4호
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• pp.635-646
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• 2012

This paper is concerned with an SIRS epidemic model with spatial diffusion and time delay representing the length of the immunity period. By using a new cross iteration scheme and Schauder's fixed point theorem, we reduce the existence of traveling wave solutions to the existence of a pair of upper-lower solutions. By constructing a newfashioned pair of upper-lower solutions, we derive the existence of a traveling wave solution connecting the uninfected steady state and the infected steady state.

• 조명전기설비학회논문지
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• 제26권2호
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• pp.51-60
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• 2012

An improved method for detecting fault distance in overhead transmission lines is described in this paper. Based on single-ended measurement, propagation theory of traveling waves together with the wavelet transform technique is used. In estimating fault location, a simple, but fundamental method using the time difference between the two consecutive peaks of transient signals is considered; however, a new method to enhance measurement sensitivity and its accuracy is sought. The algorithm is developed based on the lattice diagram for traveling waves. Representing both the ground mode and alpha mode of traveling waves, in a lattice diagram, several relationships to enhance recognition rate or estimation accuracy for fault location can be found. For various cases with fault types, fault locations, and fault inception angles, fault resistances are examined using the proposed algorithm on a typical transmission line configuration. As a result, it is shown that the proposed system can be used effectively to detect fault distance.

• Journal of applied mathematics & informatics
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• 제28권1_2호
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• pp.383-395
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• 2010

In the present paper, we construct the traveling wave solutions involving parameters of nonlinear evolution equations in the mathematical physics via the (3+1)- dimensional potential- YTSF equation, the (3+1)- dimensional generalized shallow water equation, the (3+1)- dimensional Kadomtsev- Petviashvili equation, the (3+1)- dimensional modified KdV-Zakharov- Kuznetsev equation and the (3+1)- dimensional Jimbo-Miwa equation by using a simple method which is called the ($\frac{G'}{G}$)- expansion method, where $G\;=\;G(\xi)$ satisfies a second order linear ordinary differential equation. When the parameters are taken special values, the solitary waves are derived from the travelling waves. The travelling wave solutions are expressed by hyperbolic, trigonometric and rational functions.

• 대한전자공학회논문지SD
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• 제39권7호
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• pp.37-45
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• 2002

본 논문에서는 3차원 FDTD를 이용하여 진행파형 흡수 CPW(Coplanar waveguide) 광 변조기의 마이크로파 특성을 분석하여 최적화 설계하였다. 진행파형 구조에 있어서 마이크로파의 특성은 진성 영역의 두께와 폭에 영향을 받게 되고 신호전극과 접지전극의 위치와 신호전극의 폭에도 영향을 받게 된다. 진성 영역이 InAsP/InGaP (1.3Q) 의 양자우물로 구성되었을 때, 도파관의 폭이 $2{\mu}m$, 진성영역의 두께가 $0.9{\mu}m$ 신호전극과 접지전극 사이의 간격이 $3{\mu}m$일 때 마이크로파 손실을 최소화 하며 광파와의 속도정합을 이루었으며 이때의 임피던스는 약 50${\Omega}$으로 광 변조기의 최적화를 이룰 수 있었다. FDTD를 이용하여 다양한 구조의 변화가 마이크로파에 미치는 영향을 분석 하였으며 이를 이용한 보다 정확한 소자 설계가 가능함을 보였다.

• 대한기계학회논문집A
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• 제38권5호
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• pp.567-573
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• 2014

최근에, 의학 분야의 MEMS 기술이 발전하면서 다양한 미세 유체 이송 시스템이 연구되고 있다. 본 논문에서는 기존의 펌프와는 다른, 두 개의 분리된 압전 판을 이용해 위장의 연동 운동을 모방한 마이크로 압전 펌프를 제안한다. 본 펌프는 진행파를 이용해 연동 운동을 일으켜 작동된다. 특히, 압전판에서 인가된 입력 전압에 의해 발생된 변위에 의해 동작된다. 이에 두 판 사이에서 진행파가 일어나며 유체는 진행파에 의해 생성된 압력차에 의해 이동된다. 압전 소자, 탄성체, 유체가 복합된 시스템을 이해하기 위해서 유한 요소 해석을 사용하였다. 챔버의 높이, 세라믹 개수 등의 설계 변수들을 변화시켜 유체의 유량을 확인하였다.

• 호남수학학술지
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• 제39권1호
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• pp.27-40
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• 2017

In this paper, we construct exact traveling wave solutions of various kind of partial differential equations arising in mathematical science by the system technique. Further, the $Painlev{\acute{e}}$ test is employed to investigate the integrability of the considered equations. In particular, we describe the behaviors of the obtained solutions under certain constraints.

• ETRI Journal
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• 제34권6호
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• pp.942-945
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• 2012

A high-speed traveling-wave photodetector (TWPD) with an InGaAs absorber is designed and realized. The bandwidth of the TWPD is measured using electro-optic sampling techniques. The bandwidth is 410 GHz, which shows that the RC limitation is overcome. While the TWPD shows a low responsivity of 0.06 A/W at 1,550 nm, this value can be improved through further optimization of the structure without a sacrifice in bandwidth.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권3호
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• pp.255-265
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• 2012

This paper presents a 15-GHz multiphase rotary traveling-wave voltage-controlled oscillator (RTW VCO) where a shielded coplanar stripline (CPS) is exploited to provide better shielding protection and lower phase noise at a moderate cost of characteristic impedance and power consumption. Test chips were implemented in a standard 90-nm CMOS process, demonstrating the measured results of 2-GHz frequency tuning range, -11.3-dBm output power, -109.6-dBc/Hz phase noise at 1-MHz offset, and 2-ps RMS clock jitter at 15 GHz. The chip core occupies the area of $0.2mm^2$ and dissipates 12 mW from a single 1.2-V supply.