• Title/Summary/Keyword: DOA

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Reactive Extraction of Organic Acid with Amine Extractant, I. (A Study on the Effects of Extractant and Solvent on the Degree of Extraction in Reactive Extraction of Organic Acid) (아민 추출제에 의한 유기산의 반응추출(I) (유기산의 반응추출시 추출도에 미치는 추출제 및 용매의 영향에 관한 연구))

  • Ryu, Oon-Hyung;Lee, Han-Seob;Yoo, Chul-Hwi;Kim, Yong-Yeul;Kang, An-Soo
    • Applied Chemistry for Engineering
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    • v.7 no.1
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    • pp.203-213
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    • 1996
  • In physical and reactive extraction system using equilibrium extraction equipment, the effects of extractants, concentration of extractant, and solvent on the degree of extraction were investigated. The organic acids used were acrylic acid and metacrylic acid. Extractants were n-octylamine(OA), di-n-octylamine(DOA), tri-n-octylamine(TOA) and tri-octylmetyl ammonium chloride(TOMAC ; Aliquat 336). We found that the degree of extraction for reactive extraction was 2~9 times than that for physical extraction and that effect of extractants on the degree of extraction of organic acid was the order of OA

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A Study on DOA Estimation Using Dipole Array Antenna Based on MoM (MoM 기법에 의한 다이폴 배열 안테나의 신호 방향 추정 방법 연구)

  • Moon, Sang-Kon;Lee, Kang-In;Yang, Hoon-Gee;Bae, Kyung-Bin;Chung, Young-Seek
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.7
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    • pp.661-668
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    • 2011
  • Direction estimation of signal of interest has been an important issue in radar and communication system. Generally, DOA(Direction Of Arrival) methods have been researched in the field of signal processing with ideal array sensors. However, there are some problems in array antennas such as the input signal distortions in amplitude and phase, due to the mutual coupling between array elements. In this paper, we propose a new method of DOA estimation in the dipole array antenna by using the method of moment(MoM) to compensate the mutual coupling effects between array antenna elements. Also, the proposed method is applied to the estimation of azimuth(${\phi}$ ) and elevation(${\theta}$) angles using uniformly linear dipole array under noisy environments.

Improvement of DOA Resolution Capability for Coherent Sources Using a Characteristic of Spatial Spectrums (공간 스펙트럼 특성을 이용한 코히런트 신호의 도래각 분해능 향상)

  • Park, Gwang-Moon;Lee, Hyeung-Gu;Hong, Sung-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.11
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    • pp.1201-1208
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    • 2009
  • The Direction-Of-Arrival(DOA) resolution of signals depends on the aperture size of the array. Therefore it is not easy to resolve closely spaced coherent signals impinge on an array with a small radius. In order to overcome the problem, a new method is proposed to use the characteristic of spatial spectrums for arrays which have different aperture sizes after virtually expanding the spacing of original antenna array. In case of coherent signals impinge on an uniform circular array, the perfect DOA resolution capability of 100 % is achieved at the SNR range of -10 dB to 0 dB by the Deterministic Maximum Likelihood(DML) algorithm including the proposed method. On the other hand, the standard DML algorithm can not resolve signals at all at the same SNR.

Error analysis of acoustic target detection and localization using Cramer Rao lower bound (크래머 라오 하한을 이용한 음향 표적 탐지 및 위치추정 오차 분석)

  • Park, Ji Sung;Cho, Sungho;Kang, Donhyug
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.3
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    • pp.218-227
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    • 2017
  • In this paper, an algorithm to calculate both bearing and distance error for target detection and localization is proposed using the Cramer Rao lower bound to estimate the minium variance of their error in DOA (Direction Of Arrival) estimation. The performance of arrays in detection and localization depends on the accuracy of DOA, which is affected by a variation of SNR (Signal to Noise Ratio). The SNR is determined by sonar parameters such as a SL (Source Level), TL (Transmission Loss), NL (Noise Level), array shape and beam steering angle. For verification of the suggested method, a Monte Carlo simulation was performed to probabilistically calculate the bearing and distance error according to the SNR which varies with the relative position of the target in space and noise level.

Hybrid Beamformer of CDMA Reverse Link in the Correlated SIMO Channel (CDMA 역방향 링크의 상관된 SIMO 채널을 위한 복합형 빔 성형 방식)

  • 최영관;김동구
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.11
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    • pp.81-86
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    • 2004
  • Hybrid beamformer composed of Direction-of-Arrival (DOA) based scheme followed by Maximal Ratio Combining (MRC) is proposed to overcome the degradation due to inaccurate channel estimation caused by insufficient pilot power, which happens in conventional Single-Input Multiple-Output (SIMO) Code Division Multiple Access (CDMA) reverse link. The proposed scheme could provide more accurate channel estimation and interference reduction at the expense of diversity gam in the spatially correlated SIMO channel. As a result, hybrid scheme outperforms conventional MRC beamformer for six or more antennas in the channel environment, in which Angle-of-Spread (AOS) is within 30$^{\circ}$.

Matrix Pencil Method using Fourth Order Cumulant (4차 Cumulant를 이용한 Matrix Pencil Method)

  • Jang Woo-Jin;Koh Jin-Hwan
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.43 no.2 s.308
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    • pp.87-92
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    • 2006
  • In array signal processing, high order statistics can be used to estimate parameters from signal of sums of complex exponential. This paper presents a high order Matrix Pencil method(MPM) using the fourth order cumulant. Since the fourth order cumulant can suppress the Gaussian noise, the response of MPM has better noise immunity than the conventional approaches. We successfully formulate the high order MPM with all the benefits of MPM along with higher accuracy. In the numerical simulations we demonstrated that the proposed method with forth order cumulant has better resolution to find degree of arrival(DOA) in the presence of the Gaussian noise.

Compressive Sensing for MIMO Radar Systems with Uniform Linear Arrays (균일한 선형 배열의 다중 입출력 레이더 시스템을 위한 압축 센싱)

  • Lim, Jong-Tae;Yoo, Do-Sik
    • Journal of Advanced Navigation Technology
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    • v.14 no.1
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    • pp.80-86
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    • 2010
  • Compressive Sensing (CS) has been widely studied as a promising technique in many applications. The CS theory tells that a signal that is known to be sparse in a specific basis can be reconstructed using convex optimization from far fewer samples than traditional methods use. In this paper, we apply CS technique to Multiple-input multiple-output (MIMO) radar systems which employ uniform linear arrays (ULA). Especially, we investigate the problem of finding the direction-of-arrival (DOA) using CS technique and compare the performance with the conventional adaptive MIMO techniques. The results suggest the CS method can provide the similar performance with far fewer snapshots than the conventional adaptive techniques.

A Consideration on the DOA Estimation and Signal Copy for Multiple Moving Sources (시변 다중 신호원의 DOA 추정 및 신호 취득에 대한 고찰 예)

  • Kwon, S.;Lee, J.;Park, M.K.;Kim, S.J.;Kim, C.K.
    • Proceedings of the KIEE Conference
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    • 2006.07d
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    • pp.1811-1812
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    • 2006
  • 본 논문은 공간상에서 움직이는 다중신호원의 신호 도달 방향 추정과 신호원이 보낸 신호를 다중 센서 어레이를 이용하여 판별하는 문제를 다룬다. 일반적으로 정지하고 있는 신호원의 방향 추정은 어레이에서의 출력 방정식의 방향 벡터들이 시불변인 상수이기 때문에 잡음환경 하에서도 샘플링된 벡터(Snapshot) 수가 늘어날수록 훨씬 정확하게 방향 추정이 가능하지만 신호원이 움직이는 경우에는 신호원의 방향이 변하게 되어 결국 어레이 방정식의 방향 벡터들이 시변이므로 추정값의 분산(variance)이 커지게 되어 정확한 추정이 어렵게 된다. 이러한 경우에 대한 정량적인 분석 예는 드물어 실제 여러 가지 추정 기법들의 특성이 어떻게 나타나는지 가늠하기가 어렵다. 따라서 본 논문에서는 이러한 경우에 대한 시나리오 예를 설정한 후 이 시나리오에 따른 랜덤 가우시안 잡음 하에서의 수치 데이터 모델을 생성하여 수신기에서는 미지의 값인 이 데이터에 대해 기존의 DOA 추정 기법을 이용하여 추정을 수행하여 그 정량적인 결과들을 계산해 봄으로써 시변인 경우에서의 그 성능을 판단해 보기로 한다.

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Performance Analysis of DCMP and ZF based on Spatial Channel Response Estimation by ESPRIT (ESPRIT에 의한 공간 채널응답 추정치에 기초를 둔 방향구속 전력 최소화법과 제로포싱 알고리즘의 성능평가)

  • 정중식;임정빈;안영섭
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2002.11a
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    • pp.169-174
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    • 2002
  • It has known that the DCMP(Directionally Constrained Minimization of power)and the ZF(Zero Forcing) can improve the SINR performance of an array antenna system by using spatial signature of wireless channel. This paper analyzes performance of DCMP and ZF in multiple scattering environments. To obtain the spatial signature of wireless channel. bothe DOA(Directional of Arrival) and AS(Angular Spread) of the received signals were estimated by using ESPRIT. The performance of the DCMP and the ZF was analyzed theoretically. Through computer simulation, the SINR performance were evaluated.

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The Design of Array Geometry in 2-D Multiple Baseline Direction Finding (2차원 멀티베이스라인 방향탐지 배열 구조 설계)

  • Park, Cheol-Sun;Kim, Dae-Young
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.10A
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    • pp.988-995
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    • 2006
  • In this Paper, we Present a nonharmonic may geometry design method using Euclidan minimum distance function in difference Phase spaces for 2-D (azimuth/elevation) multiple baseline antenna may which has a way to reduce the number of sensor antennas while maintaining accurate DOA estimate. The major advantages of our approach is that even the shortest interelement spacing can be larger than half-wavelength and is not limit13d to linear and it can be applied successfully to any array configuration. In multiple signals impinging situation, the performance simulation results of superresolution algorithms shows the effectiveness of the proposed method. Also the 2-D asymmetric may using the Proposed method is designed and the Performance of the manufactured away through the experimental test is verified.