• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.275-281
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• 2019

A synthetic aperture radar(SAR) satellite is more effective than an optical satellite for target analysis because an SAR satellite can provide two-dimensional electromagnetic scattering distribution of a target during all-weather and day-and-night operations. To conduct target analysis while considering the earth observation interval of an SAR satellite, observing a specific area as wide as possible would be advantageous. However, wider the observation area, worse is the resolution of the associated SAR satellite image. Although conventional methods for improving the resolution of radar images can be employed for addressing this issue, few studies have been conducted for improving the resolution of SAR satellite images and analyzing the performance. Hence, in this study, the applicability of conventional methods to SAR satellite images is investigated. SAR target detection was first applied to Korea Multipurpose Satellite-5(KOMPSAT-5) SAR images provided by Korea Aerospace Research Institute for extracting target responses. Extrapolation, RELAX, and MUSIC algorithms were subsequently applied to the target responses for improving the resolution, and the corresponding performance was thereby analyzed.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.445-458
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• 2008

Image chain analysis of synthetic aperture radar (SAR) satellite is one of the primary activities for satellite design because SAR image quality depends on spacecraft bus performance as well as SAR payload. Especially, satellite pointing and stability error make worst effect on the original SAR image quality which is implemented by SAR payload design. In this research, Image chain analysis S/W was developed in order to analyze the SAR image quality degradation due to satellite pointing and stability error. This S/W consists of orbit model, attitude control model, SAR payload model, clutter model, and SAR processor. SAR raw data, which includes total 25 point targets in the scene of $5km{\times}5km$ swath width, was generated and then processed for analysis. High resolution mode (spotlight), of which resolution is 1m, was applied. The results of image chain analysis show that radiometric accuracy is the most degraded due to the pointing error. Therefore, the successful design of attitude control subsystem in spacecraft bus for enhancing the pointing accuracy is most important for image quality.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.21-26
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• 2007

A study on analysis and application of ocean currents information extracted from SAR (Synthetic Aperture Radar) satellite image. The current information extracted from SAR satellite image is not real vector information but scalar information in normal direction of orbital path. To correct current information extracted from satellite image, observation of currents in the field is carried out at the same time and area as those of satellite image. In the analysis, current information extracted from satellite image is corrected by using observed ones. By this correction, the speed and the direction of current can be estimated. The extract current information seem to agree well with the observed ones.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.667-676
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• 2009

The payload can be classified as a passive and active type. Generally radar satellite to acquire specific information through various radar images will use the SAR (Synthetic Aperture Radar) as active type payload. the principal of SAR satellite is to receive the signal returned from certain objects and/or surfaces in order to construct an radar image. The data acquired from the satellite in its real orbit shall be needed to perform successful CAL/VAL (Calibration & Validation) because the SAR satellite have to receive the returned signal for SAR image construction. In order to do the above, the returned signal shall be related to ground targets. Especially ground target is the corner reflector (CR) for CAL/VAL. Generally the reflector has various types and shapes. Their selection can be dependent on characteristics and mission objectives of SAR satellite. In this paper, reflector focused on the optimal case and effective case has been studied and then the trihedral corner reflector under this study has been designed and its performance also analyzed.

• 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.

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.12-19
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• 2009

In the modern UAV systems, the role of radar payload has been increasing with its unique performance of day-and-night operation and see-through capability over hidden obstacles. Contrary to the satellite reconnaissance, UAV is expected to provide high resolution target detection and recognition capability while frequent flight missions would deliver enhanced SAR image and local information over the target area. STK(Satellite Tool Kit) is a professional space-analysis software widely used in all phases of a space system's life cycle. The simulation of STK is efficient and accurate relatively. In this paper, the author attempt to model the UAV operation and measure the expected SAR image quality. STK(Satellite Tool Kit) is employed to analyze UAV operation and produce SAR raw data. A SAR simulator is developed to produce high resolution SAR image for various ground targets.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.2
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• pp.160-169
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• 2007

In this paper, we have described and simulated the effect analysis and correction of phase errors in the SAR rawdata induced by satellite attitude errors such as drift, jitter. This simulation is based on the FSA(Frequency Scaling Algorithm) for high resolution image formation of the Spotlight SAR. Phase errors produce the degradation of SAR image quality such as loss of resolution, geometric distortion, loss of contrast, spurious targets, and decrease in SNR. To resolve this problem, this paper presents method for correction of phase errors using the PGA(Phase Gradient Algorithm) in connection with the FSA. Several results of the phase errors correction are presented for Spotlight SAR rawdata.

• 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 the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.601-609
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• 2014

Large number of SAR(Synthetic Aperture Radar) satellites, one type of earth observation satellite, have been developed as they have the advantage of not being affected by surrounding environment during the earth image acquisition. In order to gain high image quality, SAR antenna should have large diameter. However, internal space of satellite launch vehicle is limited and this leads SAR antenna to be designed deployable so that it can be folded in launch vehicle and unfolded in space. In this research, values of various design factors of deployable satellite antenna were chosen considering satellite's target mission. Configuration of deployable satellite antenna was designed by applying the chosen values of design factors, and variation in deployable satellite antenna during satellite maneuver was observed through simulation.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.337-339
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• 2003

This paper describes the SAR geocoding module, which is the sub-module of a IRHIS ('Integrated RS s/w for High resolution satellite ImageS'): package of 'Development of High Resolution Satellite Image Processing Technique' project in Electronics and Telecommunications Research Institute (ETRI). The function of this module is following. 1) Orbit Type : ERS1/ERS2, RADARSAT 2) Data Format : SAR CEOS Format(Single Look Complex) 3) Function: - Geocode : Generate a map projected SAR image based on only orbit information - Orthorectify: Generate a rigorous geocoded SAR image with a DEM information In this paper, we briefly describe the algorithm that is adopted to the functions, and component architecture.