• Title/Summary/Keyword: 비선형 위상

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Simulation Study of Altitude and Angle Estimation with an InSAR Altimeter (InSAR 고도계의 높이 및 각도 추정에 대한 모의실험)

  • Paek, Inchan;Lee, Sangil;Chun, Joohwan;Lee, Hyukjung;Jang, Jong Hun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.8
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    • pp.838-848
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    • 2014
  • We present a simulation study of an algorithm for the range and angle of arrival(AOA) estimation with an interferometric synthetic aperture radar(InSAR) altimeter using a real digital elevation model(DEM). We also illustrate a step-by-step procedure of generating raw InSAR data, as well as their range and azimuth compressed data, which is to be used for the subsequent altitude and angle estimation. The AOA is estimated using a deterministic maximum likelihood estimator(DMLE) applied to the first arrived point for each pulse in the compressed data obtained with three antennas. The range bin size and the pulse repetition interval(PRI) are much smaller than the cell size of the DEM used in this study. To make the DEM compatible to the radar parameters, we first generate a higher resolution DEM by linearly interpolating the given DEM. After a brief description of the principle of the InSAR altimeter, the algorithms for altitude and angle estimation are presented, and their performance is assessed through simulation.

Spatio-temporal Structure of Diurnal and Semidiurnal Tides in Geopotential Height Field (지위고도장의 일주기 및 반일주기 조석의 시공간적 구조)

  • Cho, Hyeong-Oh;Son, Seok-Woo;Lee, Yong-Hee
    • Journal of the Korean earth science society
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    • v.37 no.7
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    • pp.465-475
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    • 2016
  • The diurnal and semidiurnal tides in the global atmosphere are examined using 3-hourly geopotential height field of the state-of-the-art reanalysis data. Unlike the previous studies, the spatial structure and seasonality of those tides are analyzed from the surface of the earth to the stratosphere. It is found that, at most levels, diurnal tide is strong in the midlatitudes while semidiurnal tide is predominant in the tropics. The former shows strong seasonal cycle with a larger amplitude in summer than in winter in both hemispheres. This is different from the semidiurnal tide which has essentially no seasonal cycle. In term of the vertical structure, while semidiurnal tide has a barotropic structure, diurnal tide exhibits a distinct vertical structure with increased amplitude and height. Especially tropical diurnal tide exhibits a nearly opposite phase from the surface to the free troposphere, and to the upper stratosphere. Its amplitude also varies nonlinearly with height, possibly influenced by water vapor, ozone, gravity waves and solar radiation.

Synchronization and Secure Communication Application of Chaos Based Malasoma System (카오스 기반 Malasoma 시스템의 동기화 및 보안 통신 응용)

  • Jang, Eun-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.5
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    • pp.747-754
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    • 2017
  • Chaos-based secure communication systems are alternative of standard spread-spectrum systems that enable spreading the spectrum of the information signals and encrypting information signals with simple and inexpensive chaotic circuitry. In secure communication area, like Lorenz, Chua, Rossler, Duffing etc, classical systems are widely used. Malasoma chaotic system is topologically simple but their dynamical behaviors are non-linear synchronization and secure communication applications has not seen in paper. This paper aims for introducing a new chaotic system which is able to use as alternative to classical chaotic systems into secure communication fields. In addition, this new model simulates a synchronous communication system using P-C (Pecora-Carroll) method by verifying security with chaos signal through simulation. Modelling, synchronization and secure communication applications of Malasoma are realized respectively in MATLAB-Simulink environment. Retrieved results show that this novel chaotic system is able to use in secure communication fields.

Applicability Test of a Wetting and Drying Scheme for KU-RLMS Model (KU-RLMS 모형의 잠김-드러남 기법 적용성 평가)

  • Lee, Nam-Joo
    • The Journal of the Korea Contents Association
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    • v.11 no.4
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    • pp.448-457
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    • 2011
  • A wetting and drying(WAD) scheme was introduced in KU-RLMS which is a two-dimensional depth-averaged unsteady model, and applicability tests for wetting and drying were performed in this study. WAD scheme in the model uses a mathematically less elegant but numerically easier method to test for dry or wet cells at each time step, then to apply blocking conditions for fluxes at cells' interfaces. WAD scheme introduced in the model was verified against an analytical solution in a frictionless parabolic basin. It was found that there occurs a little phase difference between analytical and numerical solution and little decrease of amplitude of numerical result. I used three test channels having a linear sloping bottom topography, a stepwise bottom topography, and a stepwise, a bumpy and bowl-shaped bottom topography. It could be found that numerical simulation results in test channels have similar shapes of Balzano[4] and Oey[15].

Ring Hybrid Coupler with Compact Size and Wide Bandwidth (넓은 대역폭을 가지는 소형 링 하이브리드)

  • Kim, Ui-Jung;Kim, Seung-Hwan;Kim, Ell-Kou;Lee, Young-Soon;Kim, Young;Yoon, Young-Chul
    • Journal of Advanced Navigation Technology
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    • v.13 no.2
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    • pp.194-200
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    • 2009
  • This paper introduces a ring hybrid coupler using shunt capacitors, high impedance lines and CRLH-TLs (Composite Right/Left-Handed Transmission Lines) with size reduction and bandwidth enhancement. The reduced method of line length uses to combine a short length high impedance line and shunt capacitors. Also, there is combined CRLH meta-material so as to obtain wide bandwidth of transmission line using nonlinear phase characteristic of CRLH-TL that consists of series capacitors and shunt inductors. The implemented ring hybrid coupler shows a novel design with compact size that is smaller than 10% and bandwidth is larger than 60% of conventional ring hybrid coupler.

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A Study on Performance Improvement of FIR Digital Filter using Modified Window Function (변형된 창함수를 이용한 FIR 디지털 필터의 성능 향상에 관한 연구)

  • Kim, Nam-Ho;Ku, Bon-Seok
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.06a
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    • pp.758-761
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    • 2007
  • Digital signal processing technique is applied in wide fields such as speech processing, image processing and spectrum analysis. Therefore, in order to do frequency selective operation digital filter is used in stead of analog filter and sharp filter characteristics can be implemented. Since finite impulse response (FIR) digital filter as nonrecursive type represents linear phase response characteristics and is always stable and is used in fields regarding wave information importantly such as data transmission. And due to frequency characteristics, in order to remove the Gibbs phenomenon generating around a discontinuous point, filter is designed through window function method. Therefore, in this paper to improve performance of FIR digital filter, a modified window function was applied. And the proposed method was compared with conventional methods using peak side-lobe and transition properties in simulations.

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Thermal Memory Effect Modeling and Compensation in Doherty Amplifier for Pre-distorter (전치왜곡기 적용을 위한 Doherty 증폭기의 열 메모리 효과 모델링과 보상)

  • Lee, Suk-Hui;Bang, Sung-Il
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.4
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    • pp.65-71
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    • 2007
  • Doherty amplifier has more efficiency and distortion than general amplifier. These distortion classified amplitude distortion and phase distortion, memory effect distortion. This paper reports on an attempt to investigate, model and quantity the contribution of the electrical nonlinearity effects and the thermal memory effects to a doherty amplifier's distortion generation and suggests thermal memory effect compensator for pre-distorter. Also this paper reports on the development of an accurate dynamic expression of the instantaneous junction temperature as a function of the instantaneous dissipated power. The parameters of suggested model suppress thermal memory effects doherty amplifier with pre-distorter. Pre-distorter with electrothermal memory effect compensator for doherty amplifier enhanced ACLR performance about 22 dB than general doherty amplifier. Experiment results were mesured by 50W LDMOS Doherty amplifier and pre-distorter with electrothermal memory effect compensator was simulated by ADS.

Radiation Characteristics of Dielectric-Coated Conducting Cylinder Loaded with Periodic Corrugation (주기적인 구형격자로 로딩된 유전체 코팅된 도체 실린더의 복사 특성)

  • Kim, Joong-Pyo;Son, Hyon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.3
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    • pp.388-402
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    • 2000
  • The radiation characteristics of leaky antenna from the dielectric-coated conducting cylinder with periodic corrugation are investigated theoretically for the infinite and finite periodic structures. For the infinite periodic structure, mode-matching method is applied. The integral equation is derived for the finite periodic structure by use of the Fourier transform and mode expansion and a simultaneous linear equation is obtained. The influences of the corrugation slot width, corrugation depth, dielectric thickness, cylinder radius, and finite corrugation number on the radiation characteristics (leakage constant, phase constant, and radiation pattern) are investigated. The results of the finite periodic corrugations are compared with those of the infinite extent structure and good agreement is found. To reduce high side lobe levels of the uniform finite periodic structure, tapering process on the beginning and end section of antenna and nonuniform quasi-period slot arrays are considered. Especially, for the corrugation period, width and depth used for a corrugated surface wave antenna, through the proper tapering process, end-fire radiation pattern with reduced side lobe levels is given.

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Monopulse Secondary Surveillance Radar Antenna with Sum/Difference/SLS Channels (합/차/부엽 억제 채널을 갖는 모노펄스 보조 감시 레이더(용) 안테나)

  • Choi, Jong-Hwan;Chae, Hee-Duck;Park, Jong-Kuk;Na, Hyung-Gi
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.7
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    • pp.720-728
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    • 2011
  • In this paper, development of the monopulse secondary surveillance radar antenna which can be used for IFF system is presented. This antenna that is passive linear array is comprised of the row-feeder and several array-elements. The row-feeder provides sum, different and SLS(Sidelobe Supression) channels which are optimized the distribution of the power and phase ratio. The azimuthe sidelobe level of the sum channel beam pattern is -20 dBc or less. The SLS channel covers the sidelobe of the sum-chanel in the whole azimuth angle range. And the difference channel is used to perform the mono-pulse function, improves the detection accuracy in the azimuth direction. Meanwhile, the arrayelement makes shaped beam in the elevation angle, in order to eliminate the clutter and multipath effects from the ground. Performance of the antenna developed is verified by the measurement of S-parameters and far-field beam pattern, and satisfies all of the development specifications well.

A Study on an Performance Improvement of FIR Digital Filter using Window Function Design Method (창함수 설계 기법을 이용한 FIR 디지털 필터의 성능 향상에 관한 연구)

  • Lee, Kyung-Hyo;Bae, Sang-Bum;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.351-354
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    • 2007
  • In recent years, digital processing techniques have been applied diversity of fields. Typical signal processing techniques are speech processing and image processing. And filters for the signal processing can be divided in FIR (finite impulse response) filter and IIR (infinite impulse response) filter. Compared with IIR filter, the FIR Filter has a defect of high-degree, but has a merit of stability and uses simply. Futhermore, FIR filter also has linear phase response characteristics, it is using in fields regarding wave information importantly. To FIR Filter design, the main issue is to remove the Gibbs phenomenon. Therefore, in this paper I was proposed a method using FIR digital filter applied a modified window function and the method was compared with conventional methods.

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