• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1181-1194
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• 2018

This study suggests a novel approach of estimating stream flow discharge using the Synthetic Aperture Radar (SAR) images taken from 2015 to 2017 by European Space Agency Sentinel-1 satellite. Fifteen small to medium sized rivers in the Han River basin were selected as study area, and the SAR satellite images and flow data from water level and flow observation system operated by the Korea Institute of Hydrological Survey were used for model construction. First, we apply the histogram matching technique to 12 SAR images that have undergone various preprocessing processes for error correction to make the brightness distribution of the images the same. Then, the flow estimation model was constructed by deriving the relationship between the area of the stream water body extracted using the threshold classification method and the in-situ flow data. As a result, we could construct a power function type flow estimation model at the fourteen study areas except for one station. The minimum, the mean, and the maximum coefficient of determination ($R^2$) of the models of at fourteen study areas were 0.30, 0.80, and 0.99, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.6
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• pp.31-36
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• 2022

In this paper, we present the design, manufacture and test results of Backend unit for SAR(Synthetic Aperture Radar) that can be applied on a small satellite. The Backend unit for SAR was designed with a control/storage board, TRX(transmission and receiving) board and a power supply board as a single unit in consideration of the applying of a small satellite. The control/storage board uses RFSoC to generate wideband chirp signal, generate operating timings, and perform control and calculations for SAR operation. The TRX board is designed to convert the wideband chirp signal generated by the control/storage board to the operating frequency of X-band by up-converting the frequency. Since small size, light weight, and low cost are important consideration for small satellite, MIL/Industrial grade components were appropriately applied and the at the same time it was designed to ensure mission life through the radiation test, analysis and space environment tests.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.128-133
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• 1998

To assess the flood damages and to provide necessary information for preventing future catastrophe, it is necessary to appraise the inundated area with more accurate and rapid manner. This study attempts to evaluate the potential of satellite synthetic aperture radar (SAR) data for mapping of flood inundated area in southern part of Korea. JERS L-band SAR data obtained during the summer of 1997 were used to delineate the inundated areas. In addition, Landsat TM data were also used for analyzing the land cover condition before the flooding. Once the two data sets were co-registered, each data was separately classified. The water surface areas extracted from the SAR data and the land cover map generated using the TM data were overlaid to determine the flood inundated areas. Although manual interpretation of water surfaces from the SAR image seems rather simple, the computer classification of water body requires clear understanding of radar backscattering behavior on the earth's surfaces. It was found that some surface features, such as rice fields, runaway, and tidal flat, have very similar radar backscatter to water surface. Even though satellite SAR data have a great advantage over optical remote sensor data for obtaining imagery on time and would provide valuable information to analyze flood, it should be cautious to separate the exact areas of flood inundation from the similar features.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.2
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• pp.141-151
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• 2019

In this study, we propose a performance analysis of a quadrature-polarimetric(quad-pol) synthetic aperture radar(SAR) system for wide-swath operation mode and compare it with a single-pol system based on the operation mode. To achieve a shorter revisit time for an SAR satellite, we must observe a wide area, and two SAR operation modes exist for this purpose, which are called ScanSAR and SweepSAR. In general, a quad-pol SAR system can obtain a greater variety of information about a target than a single-pol system. Because this system affects system performance parameters, analyzing these effects is required. Based on a performance analysis of the wide-swath quad-pol SAR system, the system parameters and appropriate operation mode can be selected to satisfy the performance requirements.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.183-196
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• 1998

The Synthetic Aperture Radar(SAR) image and the Digital Elevation Model(DEM) of an target area are put into use to generate three dimensional image map. An method of image map generation is explained. The orbit and attitude determination of satellite makes it possible to model signal acquisition configuration precisely, which is a key to mapping image coordinates to geographic coordinates of concerned area. An application is made to RADARSAT in the purpose of testing its validity. To determine the orbit, zero Doppler range is used. And to determine the attitude, Doppler centroid frequency, which is the frequency observed when target is put in the center of antenna's view, is used. Conventional geocoding has been performed on the basis of direct method(mapping image coordinates to geographic coordinates), but in this reserch the inverse method(mapping from geographic coordinates to image coordinates) is taken. This paper shows that precise signal acquisition modeling based on the orbit and attitude determination of satellite as a platform leads to a satellite-centered accurate geocoding process. It also shows how to model relative motion between space-borne radar and target. And the relative motion is described in ECIC(earth-centered-initial coordinates) using Doppler equation and signal acquisition geometry.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.2
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• pp.87-97
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• 2000

Recently microwave remote sensing technology is widely used in Global environment study. Expecially Synthetic Aperture Radar sensing technique has many application to geographic information. Proposed AIRSAR Pacific Rim Deployment 2000(PACRIM2) is a NASA-sponsored science mission. AIRSAR is a test-bed instrument for new radar technologies in near future from space shuttle and satellite systems. In this paper the overview of PACRIM2 overview and sensors are introduced. Examples of processed data from new sensors are also shown.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.683-691
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• 2014

Significance of SAR(Synthetic Aperture Radar) satellite regadless of weather have grown for Earth observation. According to the cost-effective trend in satellite development, SAR antenna is actively studied. It's a competitive candidate to use deployable SAR antenna out of CFRP. In this study, variables for an antenna configuration model was researched and evaluated. The design of the antenna was structurally analyzed by FEM(Finite Element Model). Tool-kit was developed for modifying the SAR antenna model easily in accordance with system requirement change. In the tool-kit, antenna configuration design and error analysis of the antenna surface could be achieved. And compatibility of tool-kit results to CST, a RF analysis program, was confirmed.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.63-69
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• 2005

Interferometric Synthetic Aperture Radar(InSAR) is a rapidly evolving technique. Spectacular results obtained in various fields such as the monitoring of earthquakes, volcanoes, land subsidence and glacier dynamics, as well as in the construction of Digital Elevation Models(DEMs) of the Earth's surface and the classification of different land types have demonstrated its strength. As InSAR is a remote sensing technique, it has various sources of errors due to the satellite positions and attitude, atmosphere, and others. Therefore, it is important to validate its accuracy, especially for the DEM derived from Satellite SAR images. In this study, Real Time Kinematic(RTK) GPS and Kinematic GPS positioning were chosen as tools for the validation of InSAR derived DEM. The results showed that Kinematic GPS positioning had greater coverage of test area in terms of the number of measurements than RTK GPS. But tracking the satellites near and/or under trees md transmitting data between reference and rover receivers are still pending tasks in GPS techniques.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.1
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• pp.30-44
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• 2022

The advent of deep learning-based algorithms has facilitated researches on target detection from synthetic aperture radar(SAR) imagery. While most of them concentrate on detection tasks for ships with open SAR ship datasets and for aircraft from SAR scenes of airports, there is relatively scarce researches on the detection of SAR ground vehicle targets where several adverse factors such as high false alarm rates, low signal-to-clutter ratios, and multiple targets in close proximity are predicted to degrade the performances. In this paper, a dataset of ground vehicle targets acquired from TerraSAR-X(TSX) satellite SAR images is presented. Then, both detection and instance segmentation are simultaneously carried out on this dataset based on the deep learning-based Mask R-CNN. Finally, this paper shows the future research directions to further improve the performances of detecting the SAR ground vehicle targets.

• Journal of the Korean Solar Energy Society
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• v.37 no.5
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• pp.49-63
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• 2017

Solar cells have widely been utilized for a satellite to convert sunlight energy into electricity in space. Many different types of solar cells appropriate for each satellite program are available in current markets, which enables us to construct a solar array light and small often required from a low Earth orbit (LEO) synthetic aperture radar (SAR) satellite. Thus, it is important to choose a proper solar cell satisfying the requirements of mass and size for the solar array. In this article, we have surveyed typical suppliers and have discussed some characteristics of solar cells. Conceptual design examples of the solar array for LEO SAR satellites using several types of solar cells have been performed to show the pros and cons of solar cells by comparison of the total mass and size necessary for the solar array.