• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.6-12
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• 2017

Recently, the demand for SAR imaging is growing to monitor natural disasters or military sites to foresee topographic changes, where optical sensing is not easily available. High-resolution SAR images are useful in exploring topography and monitoring artificial land objects in all weather conditions. In this paper,high resolution SAR images acquired from KOMPSAT-5 are exploited for the applications of change detection and classification. In order to detect change areas, amplitude change detection (ACD) and coherence change detection (CCD) algorithms are employed and their performances are compared in practical applications. For enhanced performance, the potential of small scaled change detection is explored by combining multi-temporary SAR images. The k-means and SVM methods are applied for land classifications and their performances are compared by applying to the real spaceborne SAR images.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1258-1270
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• 2000

A synthetic aperture radar (SAR) system is able to provide all-weather, day-and-night, high resolution imaging capability in the wide area of interest, and thus is extremely useful in surveillance for both civil and military applications. In this paper, the X-band high-resolution spaceborne SAR system design is described with the key design parameters for the mission and system requirement characterized by the small satellite platform. The SAR imaging mode design technique is presented, and the standard imaging mode design results are analyzed with respect to image quality performance. In line with the system requirement, X-band SAR payload and ground reception/processing subsystems are designed and the key design results are demonstrated with the outstanding performance characteristics. The designed small satellite SAR system shows the wide range of imaging capability, and proves to be an effective surveillance systems in the light weight, high performance and cost-effective points of view.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.125-132
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• 2024

Optical satellite images are being used for national security and collection of information, and their utilization is increasing. However, it acquires low-quality images that are not suitable for the user's requirement due to weather conditions and time constraints. In this paper, a deep learning-based conversion of image and colorization model referring to high-resolution SAR images was created to simulate the occluded area with clouds of optical satellite images. The model was experimented according to the type of algorithm applied and input data, and each simulated images was compared and analyzed. In particular, the amount of pixel value information between the input black-and-white image and the SAR image was similarly constructed to overcome the problem caused by the relatively lack of color information. As a result of the experiment, the histogram distribution of the simulated image learned with the Gray-scale image and the high-resolution SAR image was relatively similar to the original image. In addition, the RMSE value was about 6.9827 and the PSNR value was about 31.3960 calculated for quantitative analysis.

• Current Industrial and Technological Trends in Aerospace
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• v.4 no.2
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• pp.40-48
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• 2006

SAR(Synthetic Aperture Radar, 이하 SAR) 위성영상은 광학 영상과는 달리 기상조건의 영향을 거의 받지 않아 대상지역의 주기적인 모니터링이 가능하며, 특정주파수 영역밴드에서는 지표면 투과탐지가 가능하여 재난, 재해, 국방, 환경 분야 등 점차 활용범위가 확대되고 있는 추세이다. 그간의 고해상도 광학위성영상의 기술 개발이 지속적으로 이루어진 상황이라면 그에 비해 영상처리절차가 비교적 까다롭고 복잡한 SAR 영상에 관한 기술개발은 영상 활용의 가치를 가늠해 볼 때 특히 국내 경우 많이 저조한 실정이다. 이와 같은 상황을 고려해 볼 때 현재 개발되고 앞으로 계획단계에 있는 SAR 지구관측 위성의 개발 동향을 파악함으로서 SAR 영상 활용기반구축 마련 및 장기적인 연구개발 계획수립에도 효과적으로 이용될 수 있을 것으로 생각한다.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.131-141
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• 2014

Synthetic Aperture Radar (SAR) is a powerful and well established microwave remote sensing technique which enables high resolution measurements of the Earth surface independent of weather conditions and sunlight illumination. In this study, this paper first summarizes the basic SAR theory and the history of the SAR satellites. The second part of this paper gives an overview of new technologies for future SAR systems. New innovative concepts and technologies for SAR satellites will be digital beamforming, High Resolution Wide Swath (HRWS), Waveform Encoding, Terrain Observation by Progressive Scan (TOPS), and so on. These technologies will play an important role for future spaceborne SAR satellites.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.1
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• pp.75-86
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• 2012

Synthetic Aperture Radar(SAR) imaging system is independent of solar illumination and weather conditions; however, SAR image is difficult to interpret as compared with optical images. It has been increased interest in multi-sensor fusion technique which can improve the interpretability of $SAR^{\circ\circ}$ images by fusing the spectral information from multispectral(MS) image. In this paper, a multi-sensor fusion method based on high-frequency extraction process using Fast Fourier Transform(FFT) and outlier elimination process is proposed, which maintain the spectral content of the original MS image while retaining the spatial detail of the high-resolution SAR image. We used TerraSAR-X which is constructed on the same X-band SAR system as KOMPSAT-5 and KOMPSAT-2 MS image as the test data set to evaluate the proposed method. In order to evaluate the efficiency of the proposed method, the fusion result was compared visually and quantitatively with the result obtained using existing fusion algorithms. The evaluation results showed that the proposed image fusion method achieved successful results in the fusion of SAR and MS image compared with the existing fusion algorithms.

• Journal of Advanced Navigation Technology
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• v.5 no.2
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• pp.149-157
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• 2001

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution. It is due to the strict requirement for the real-time data transmission from a series of massive raw image data of spaceborne SAR to the ground station in a limited time of mission. In this paper, based on the data link model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• Korean Journal of Remote Sensing
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• v.31 no.3
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• pp.255-265
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• 2015

Very high resolution (VHR) satellite imagery provide valuable information on urban change monitoring due to multi-temporal observation over large areas. Recently, there has been increased interest in the urban change detection technique using VHR Synthetic Aperture Radar (SAR) imaging system, because it can take images regardless of solar illumination and weather condition. In this paper, we proposed a texture-based urban change detection method using the VHR SAR texture features generated from Gray-Level Co-Occurrence Matrix (GLCM). In order to evaluate the efficiency of the proposed method, the result was compared, visually and quantitatively, with the result of Non-Coherent Change Detection (NCCD) which is widely used for the change detection of VHR SAR image. The experimental results showed the greater detection accuracy and the visually satisfactory result compared with the NCCD method. In conclusion, the proposed method has shown a great potential for the extraction of urban change information from VHR SAR imagery.

• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.26-39
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• 2006

A synthetic aperture radar (SAR) system can provide all-weather, day and night imaging capability, and thus, is very useful in surveillance for both civil and military applications. In this paper, the X-band spaceborne SAR system design procedure is introduced with the key design parameters for mission and system requirements characterized by the small satellite platform. The SAR imaging mode design technique is presented, and the design results are analyzed for standard mode performance evaluation. In line with the system requirements, the X-band SAR payload and ground reception/processing sub-systems are presented with the key design results and image applications examples. The designed small satellite SAR system shows the wide range of imaging capability, and proves to be an effective surveillance system in light-weight, high-performance and cost-effective points of view.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.464-472
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• 2018

Future spaceborne satellite synthetic aperture radar(SAR) system is expected to acquire high-resolution images over wide swath areas. Conventional SAR systems suffer from ambiguity problems in both azimuth and range directions that lead to image quality degradation. Recently, multiple input multiple output(MIMO) SAR techniques having multiple orthogonal waveforms are proposed to overcome the conventional ambiguity problems in wide-swath imaging modes. In this paper, noisy orthogonal frequency division multiplex(OFDM) waveforms are developed to reduce the ambiguity problems and suppress the image quality degradation. SAR simulations are performed to evaluate the performance of the proposed technique for wide-swath SAR imaging.