• Journal of Positioning, Navigation, and Timing
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• 제6권2호
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• pp.43-51
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• 2017

In this study, the effect of the steering vector model mismatch due to array uncertainties on the performance of array processing was analyzed through simulation, along with the alleviation of the model mismatch effect depending on array calibration. To increase the reliability of the simulation results, the actual steering vector of the array antenna obtained by electromagnetic simulation was used along with the Jahn's channel model, which is an experimental channel model. Based on the analysis of the power spectrum for each direction, beam pattern, and the signal-to-interference-plus-noise ratio of the beamformer output, the performance deterioration of array processing due to array uncertainties was examined, and the performance improvement of array processing through array calibration was also examined.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.143-148
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• 2006

The goal of this paper is to analyze, through simulations and experiments, GNSS interference mitigation performance under various types of antenna structures against wideband and narrowband interferences using spatial-temporal adaptive signal processing (STAP) techniques. The STAP approach, which combines spatial and temporal processing, is a viable means of GNSS array signal processing that enhancing the desired signal quality and providing protection against interference. In this paper, we consider four types of 3D antenna array structure - Uniform Linear Array (ULA), Uniform Rectangular Array (URA), Uniform Circular Array (UCA), and the Single-Ring Cylindrical Array (SRCA) under an interference environment. Analytical evaluation and simulations are performed to investigate the system performance. This is followed by simulation GPS orbits in interfered environment are used to evaluate the STAP performance. Furthermore, experiments using a 2x2 URA hardware simulator data show that with the removal of wideband and narrowband interference through the STAP techniques, the signal tracking performance can be enhanced.

• 한국산업융합학회 논문집
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• 제6권4호
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• pp.361-366
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• 2003

Most sensor array signal processing methods for multiple source localization require knowledge of the correct shape of array(the correct positions of sensors that consist array), because sensor position uncertainty can severely degrade the performance of array signal processing. In particular, it is assumed that the correct positions of the sensors are known, but the known positions may not represent the true sensor positions. Various algorithms have been proposed for 2-D sensor array shape calibration in far field environment. However, they are not available in near field. In this paper, 3-D sensor array shape calibration algorithm is proposed, which is available in near field.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.375-378
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• 2017

전 세계적으로 해운물류 안전 보안체계가 강화됨에 따라 국가물류보안 체계 구축을 위한 해운물류안전 보안 핵심기술 개발이 이루어지고 있다. 또한 미국에서 2018년 시행예정인 컨테이너 사전 100% 전수검사에 대응하기 위한 컨테이너 검색기의 핵심구성 요소인 Array 검출 System의 국산화 개발이 필요하다. 본 논문에서는 현재 해외제품을 대체할 Array 검출 system 중 자체 개발한 Digital Signal Processing Board에 대한 연구를 제안하고자 한다.

• 전자공학회논문지A
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• 제30A권3호
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• pp.67-75
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• 1993

In many practical applications of systolic array, it is common that the problem size(n) is larger than the array size(M). In this case, the problem has to be partitioned into block to fit into the array before it is processed. This paper presents a problem partition method for dynamic programming and 2-dimensional systolic array suitable for it. Designed array has two types of array configur-ation for processing the partitioned problem. The queue is designed for storing and recirculating the intermediate results in the correct location and time. The number of processing elements and queues required are M(3M+1)/2, 4M respectively. The total processing time is 2(M+1)+(n+10M+3)(n/M-1)(n/M-1)/6.

• 한국군사과학기술학회지
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• 제16권3호
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• pp.382-389
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• 2013

In anti-jamming GPS receiver, adaptive signal processing techniques in which the radiation pattern of adaptive array antenna of elements may be adaptively changed used to reject interference, clutter, and jamming signals. In this paper, I describes adaptive signal processing technique using the sample matrix inversion(SMI) algorithm. This adaptive signal processing technique can be applied effectively to wideband/narrowband anti-jamming GPS receiver because it does not consider the satellite signal directions and GPS signal power level exists below the thermal noise. I also analyzed the effects of covariance matrix sample size and diagonal loading technique on the system performance of five-element circular array antenna. To attain near optimum performance, more samples required for calculation covariance matrix. Diagonal loading technique reduces the system nulling capability against low-power jamming signals, but this technique improves robustness of adaptive array antenna.

• 한국산업융합학회 논문집
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• 제26권4_1호
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• pp.517-527
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• 2023

Many techniques have been proposed and investigated for microlens array manufacturing in three-dimensional (3D) structures. We present fabricating a microlens array using selective laser etching and a CO₂ laser. The femtosecond laser was employed to produce multiple micro-cracks that comprise the predesigned 3D structure. Subsequently, the wet etching process with a KOH solution was used to produce the primary microlens array structures. To polish the nonoptical surface to the optical surface, we performed reflow postprocessing using a CO₂ laser. We confirmed that the micro lens array can be manufactured in three primary shapes (cone, pyramid and hemisphere). Compared to our previous study, the processing time required for laser processing was reduced from approximately 1 hour to less than 30 seconds using the proposed processing method. Therefore, micro lens arrays can be manufactured using our processing method and can be applied to mass productionon large surface areas.

• 한국정보통신학회논문지
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• 제22권3호
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• pp.499-505
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• 2018

전 세계적으로 해운물류 안전 보안체계가 강화됨에 따라 국가물류보안 체계 구축을 위한 해운물류안전 보안 핵심기술 개발이 이루어지고 있다. 또한 미국에서 2018년 시행예정인 컨테이너 사전 100% 전수검사에 대응하기 위한 컨테이너 검색기의 핵심구성 요소인 Array 검출 시스템의 국산화 개발이 필요하다. 본 논문에서는 현재 자체 개발한 Test Digital 신호처리 Board를 가지고 TI-RTOS(Texas Instruments - Real Time Operating System)를 이용하여 개발한 Test Software Program을 제안한다. M4 MCU를 기반으로 GPIO, SRAM, TCP/IP와 SDcard등을 테스트 할 수 있는 프로그램을 개발했다. 또한 Array 검출 system 중 자체 개발한 Digital Signal Processing Board에 대한 연구를 제안하고자 한다. M4 MCU를 테스트 할 수 있는 테스트보드를 개발했고 FPGA와 MCU가 결합된 통한 X-RAY 디지털 신호처리 보드를 개발했다.

• 한국음향학회지
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• 제35권2호
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• pp.125-133
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• 2016

최근 고해상도의 해저면 영상을 취득하기 위한 합성개구 신호처리 및 수중 시스템 개발 연구가 여러 국가에서 활발히 진행 중에 있다. 국내에서도 합성개구소나의 필요성 및 중요성을 인식하여 기초적인 관련 연구가 시작되었으나 수신 배열 센서의 이동 속도에 의한 도플러 효과가 대부분 무시되어 왔다. 본 논문에서는 수신 배열 센서의 이동 속도에 따른 영향을 확인하기 위하여 공간 주파수 영역 보간법을 이용한 수동형 합성개구 신호처리 결과의 영상 왜곡 및 오차를 분석한다. 센서의 이동을 고려하지 않은 원래의 송신 신호만을 사용하는 경우 센서의 이동 속도가 증가함에 따라 음원의 위치 추정 오차가 증가하며 영상 왜곡이 현상이 뚜렷하게 나타난다. 센서의 이동을 고려하여 보정된 신호를 사용하는 경우 정확한 위치 추정이 가능하며 영상 왜곡 현상은 나타나지 않는다. 결론적으로 1 m/s 이상의 속도에서는 센서의 이동에 의한 도플러 현상을 보정하기 위한 알고리듬 적용이 필수적이다.

• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.291-296
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• 2021

Recently, the dual-polarized antenna array has drawn attention due to the dependency of its signal processing gain on the signal polarization. Even though this polarization dependency makes it possible to mitigate a non-right-hand circularly polarized (non-RHCP) jamming signal from the same direction as a GPS signal, the dual-polarized antennas are not yet widely used for various applications. This study suggests a method that can acquire the polarization dependency of the signal-processing gain by intentionally misaligning antenna elements in a single-polarized antenna array. The simulation results show that the proposed method can successfully mitigate a non-RHCP jammer from the same direction as a GPS signal as if a dual-polarized antenna array does and provide comparable signal-to-jammer-plus-noise ratio (SJNR) performance with a completely aligned single-polarized antenna array and a dual-polarized antenna array.