• Title/Summary/Keyword: Complex Antenna System

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Space-Frequency Block Coded Single Side Band SC-FDMA Transmission System (주파수 공간 블록 부호화된 단일 측대 파형 SC FDMA 전송 시스템)

  • Won, Hui-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.7
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    • pp.423-429
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    • 2019
  • Recently, a variety of methods for the performance improvement of ultra-high speed wideband wireless transmission systems have been suggested. This paper proposes a space-frequency (SF) block coded single side band (SSB) single carrier (SC)-frequency division multiple access (FDMA) transmission system. In the proposed SSB SC-FDMA system, SF block code is implemented with the complex conjugates, which are formed from discrete Fourier transform (DFT) spreading of pulse amplitude modulation (PAM) signals. As a result, transmit diversity gain can be obtained in the proposed SF block coded SSB SC-FDMA system without any significant increase of the system computational complexity. The simulation result shows that the signal-to-noise power ratio (SNR) performance of the proposed SF block coded SSB SC-FDMA system is approximately 4 dB better than the SNR performance of the conventional SSB SC-FDMA system with single transmit antenna at a symbol error rate (SER) of $10^{-2}$.

A Free-Space Method for Measurement and Analysis of Dielectric Characteristics of Electromagnetic Absorbing Materials at Microwave Frequencies (자유공간 기법을 적응한 마이크로파 대역 전파흡수재의 유전 특성 분석)

  • 배근식
    • Journal of the Korea Institute of Military Science and Technology
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    • v.6 no.2
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    • pp.73-82
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    • 2003
  • For measurements and analysis of dielectric characteristics of planar slabs of microwave absorbing materials, I have applied a free-space method in the frequency range of 8~14 GHz. The measurement system for free-space method consists of transmit and receive antennas, mode transitions, precision coaxal cables, the network analyzer, and a computer Special Spot-focused horn lens antenna was used to eliminate diffraction effects. Diffraction effects at the edges of the sample are minimized by satisfying the condition for minimum transverse dimension of the plate and the beamwidth of the antennas at the focus. The time-domain gating feature of the network analyzer and the thru, reflect, and line(TRL) calibration technique were used to eliminate the effects of undesirable multiple reflections. The complex coefficients of reflection and transmission, $S_{11}$ and $S_{21}$, of planar samples were measured for standard materials such as Teflon, Rexolite$\textregistered$ 2200. The results were compared with existing measurement method. And I applied a free-space method for measurement to measure dielectric constants of some electromagnetic absorbing materials. Dielectric properties for the same samples were also measured with a 7mm coxial transmission line method for purposes of comparison with the free-space method.

The Application Technique on AI and Statistical Analysis of 3d-PD (3d-PD의 통계적 고찰과 신경망 응용기술)

  • Lim, Jang-Seob;Park, Yong-Sik;Choi, Byoung-Ha;Han, Sok-Kyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05a
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    • pp.66-70
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    • 2001
  • The partial discharge testing is widely used in diagnostic measuring technology because it gives low stress to power equipment which is undertaken tests. Therefore it is very useful method compare to previous destructive methods and effective diagnosis method in power system that requires on-line/on-site diagnosis. But partial discharges have very complex characteristics of discharge pattern, so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated system is manufactured and HFPD occurred from those simulator is measured with broad-band antenna in real time, the degradation grade of system is analyzed through produced patterns in simulated target according to the AI/statistics processing.

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Statistic Pattern Analysis of HFPD According to Applied Stress (인가 스트레스에 따른 HFPD의 통계적 패턴해석)

  • Kim, Duck-Keun;Lee, Eun-Suk;Jung, Young-Ill;Lim, Jang-Seub;Kim, Tae-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05a
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    • pp.18-22
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    • 2000
  • The partial discharge testing is widely used in insulation property measurement because it gives low stress to high voltage equipment which is undertaken tests. Therefore it is very useful method compare to previous destructive methods and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

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A Study on the Sensitivities Characteristics in a PD and a HFPD (PD 측정과 HFPD의 감도특성에 관한 연구)

  • Lim, Jang-Seob;Kim, Duck-Keun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05a
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    • pp.29-32
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    • 2000
  • The partial discharge testing is widely used in insulation property measurement because it gives low stress to high voltage equipment which is undertaken tests. Therefore it is very useful method compare to previous destructive methods and effective diagnosis method in power transformer that requires on-line & on-site diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and PD/HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

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Numerical Investigation of Complex System for Electrical Energy Harvesting and Vibration Isolation (미소진동 발생원으로부터의 전기에너지 재생 및 진동절연을 위한 복합 시스템의 해석적 검토)

  • Kwon, Sung-Cheol;Jo, Mun-Shin;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.8
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    • pp.648-653
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    • 2014
  • Fly-wheel, gimbal antenna, mechanical gyro and cryocooler with moving parts generate a micro-vibration during their on-orbit operation. For the acquisition of high quality image of observation satellite, additional technical efforts are required to reduce the micro-vibration level from the vibration sources. In this study, we proposed a passive isolation system combined with a tuned mass damper-type energy harvester to generate electrical energy from the micro-vibration which has always been subjected to useless isolation objectives. The feasibility of the system has been investigated through the numerical simulation.

FPGA Implementation of Unitary MUSIC Algorithm for DoA Estimation (도래방향 추정을 위한 유니터리 MUSIC 알고리즘의 FPGA 구현)

  • Ju, Woo-Yong;Lee, Kyoung-Sun;Jeong, Bong-Sik
    • Journal of the Institute of Convergence Signal Processing
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    • v.11 no.1
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    • pp.41-46
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    • 2010
  • In this paper, the DoA(Direction of Arrival) estimator using unitary MUSIC algorithm is studied. The complex-valued correlation matrix of MUSIC algorithm is transformed to the real-valued one using unitary transform for easy implementation. The eigenvalue and eigenvector are obtained by the combined Jacobi-CORDIC algorithm. CORDIC algorithm can be implemented by only ADD and SHIFT operations and MUSIC spectrum computed by 256 point DFT algorithm. Results of unitary MUSIC algorithm designed by System Generator for FPGA implementation is entirely consistent with Matlab results. Its performance is evaluated through hardware co-simulation and resource estimation.

HFPD Characteristic Analysis of Simulated Transformer According To Applied Voltage (인가전압에 따른 모의변압기의 HFPD 특성분석)

  • Kim, Duck-Keun;Im, Young-Sham;Lim, Jang-Seob;Moon, Chae-Joo;Lee, Jin
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1957-1959
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    • 2000
  • The PD measurement method is very useful to detect insulation degradation. Recently, the HFPD(High Frequency Partial Discharge) measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires in-service diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In this study, simulated transformer is manufactured and HFPD occurred from simulated transformer is measured with broad band antenna and active-line RF measurement system in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages. Also the PD pattern which was measured with EMC analyzer and RF measurement system is compared.

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Wideband Jamming Signal Remove Using Adaptive Array Algorithm (적응배열 알고리즘을 이용한 광대역 재밍 신호 제거)

  • Lee, Kwan-Hyeong
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.12 no.4
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    • pp.419-424
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    • 2019
  • In this paper, we proposed an algorithm to estimate the desired target in wideband jamming signal environment. In order to suppress the jamming signal, we use the spatial time adaptive algorithm and QR decomposition to obtain the optimal weight. The spatial time adaptive algorithm of adaptive array antenna system multiplies the tap delay signal by a complex weight to obtain a weight. In order to minimize the power consumption because of the inverse matrix, optimal weight is obtained by using QR decomposition. Through simulation, we compare and analyze the performance of the proposed algorithm and the existing algorithm. In the target estimation of [-40o,0o,+40o], the proposed algorithm estimated all three targets, but the existing algorithm estimated only [0o] due to of the jamming signal. We prove that the proposed algorithm improves performance by removing the jamming signal and estimating the target accurately.

Design and Evaluation of Hybrid Digital Retrodirective Array Antenna System (하이브리드 디지털 RDA 시스템의 설계와 평가)

  • Park, Hae-Gyu;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.5
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    • pp.251-257
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    • 2014
  • Digital RDA system is retransmit into the opposite direction of the incident signals. Digital RDA system have a disadventage that this system do not signal classification in multipath environment. because multipath signal is shown as vector sum of multipath signal, digital RDA system required complex signal process for multipath signal classification. In this paper, to solve these problem we propose hybrid digital RDA system which combination of the MUSIC algorithm and the digital RDA system. Proposed system has two modes. First mode is digital RDA mode. Secornd mode is digital beamforming mode. Digital RDA mode is used in situations where the less the impact of multipath. Digital beamforming mode is applied to multipath effects is greater. In secornd mode, we find optimal path using MUSIC algorithm. After than the proposed system uses only the optimal path. Through the proposed system in a multipath environment with digital RDA can be used to supplement a disadvantage.