• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.181-190
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• 2011

Since the radar satellite missions such as TerraSAR-X and COSMO-SkyMed were launched in 2007, the spatial resolution of spaceborne SAR(Synthetic Aperture Radar) images reaches about 1 meter at spotlight mode. In 2011, the first Korean SAR satellite, KOMPSAT-5, will be launched, operating at X-band with the highest spatial resolution of 1 m as well. The improved spatial resolution of state-of-the-art SAR sensor suggests expanding InSAR(Interferometric SAR) analysis in urban monitoring. By the way, the shadow and layover phenomena are more prominent in urban areas due to building structure because of inherent side-looking geometry of SAR system. Up to date the most conventional algorithms do not consider the return signals at the frontage of building during InSAR phase and SAR intensity simulation. In this study the new algorithm introducing multi-scattering in layover region is proposed for phase and intensity simulation, which is utilized a precise LIDAR DSM(Digital Surface Model) in urban areas. The InSAR phases simulated by the proposed method are compared with TerraSAR-X spotlight data. As a result, both InSAR phases are well matched, even in layover areas. This study will be applied to urban monitoring using high resolution SAR data, in terms of change detection and displacement monitoring at the scale of building unit.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.169-173
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• 2019

In this paper, SAR payload operation mode design method, results and performance analysis results are suggested. To SAR payload design, pramary parameter should be identified and designed. It is designed considering the small satellite of less than 100kg operated in low earth orbit. Also, an antenna structure for small size and light weight is proposed. Performance analysis is performed by applying the design values.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.75-86
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• 2010

As the performance of the spaceborne SAR has been dramatically enhanced and demonstrated through advanced missions such as TerraSAR and LRO(Lunar Reconnaissance Orbiter), the need for highly sophisticated and efficient SAR processor is also highlighted. In Korea, the activity of SAR researches has been mainly concerned with SAR image applications and the current SAR raw data studies are mostly limited to stripmap mode cases. The first Korean spaceborne SAR is scheduled to be operational from 2010 and expected to deliver vast amount of SAR raw data acquired from multiple operational scenarios including ScanSAR mode. Hence there will be an increasing demand to implement ground processing systems that enable to analyze the acquired ScanSAR data and generate corresponding images. In this paper, we have developed an efficient ScanSAR processor that can be directly applied to spaceborne ScanSAR mode data. The SPECAN(Spectrum Analysis) algorithm is employed for this purpose and its performance is verified through RADARSAT-1 ScanSAR raw data taken over Korean peninsular. An efficient quick-look processing is carried out to produce a wide-swath SAR image and compared with the conventional RDA processing case.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.847-859
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• 2021

Recently, as the number of high-resolution satellite SAR images increases, the demand for precise matching of SAR imagesin change detection and image fusion is consistently increasing. RMSE (Root Mean Square Error) values using GCPs (Ground Control Points) selected by analysts have been widely used for quantitative evaluation of image registration results, while it is difficult to find an approach for automatically measuring the registration accuracy. In this study, a feasibility analysis was conducted on using the FSIM (Feature Similarity) index as a measure to evaluate the registration accuracy. TerraSAR-X (TSX) staring spotlight data collected from various incidence angles and orbit directions were used for the analysis. FSIM was almost independent on the spatial resolution of the SAR image. Using a single SAR image, the FSIM with respect to registration errors was analyzed, then use it to compare with the value estimated from TSX data with different imaging geometry. FSIM index slightly decreased due to the differencesin imaging geometry such as different look angles, different orbit tracks. As the result of analyzing the FSIM value by land cover type, the change in the FSIM index according to the co-registration error was most evident in the urban area. Therefore, the FSIM index calculated in the urban was mostsuitable for determining the accuracy of image registration. It islikely that the FSIM index has sufficient potential to be used as an index for the co-registration accuracy of SAR image.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.833-838
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• 2005

In this paper, we propose SAR(Specific absorption rate) reduction methods based on surface electric field distribution relation for mobile handsets. Proposed the new method that is able to consider improvement of the SAR from the very beginning step of developing the mobile handsets. Analysis of mobile handset with human body(head) using finite element method(FEM). Results of this method, SAR reduced about $50\;\%$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.346-349
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• 2005

In this paper, we propose SAR(Specific absorption rate) reduction methods based on surface electric field distribution relation. Proposed the new method that is able to consider improvement of the SAR from the very beginning step of developing the wireless transceiver. Analysis of wireless handset with human body(head) using finite element method(FEM). Results of this method, SAR reduced about 50 %.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.61-64
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• 2007

SAR 영상에 존재하는 군사표적은 광학 영상에 있는 군사표적에 비하여 쉽게 구별하기 힘들다. 이는 전체 영상에서 군사표적을 구성하는 픽셀의 수가 매우 적기 때문이다. 이러한 문제 때문에 SAR 영상 분석가들은 영상을 분석하는 것이 어렵다. 이 문제를 해결하기 위해서는 자동화된 분석 시스템이 필요하다. 본 논문에서는 기존에 연구된 SAR 영상을 이용한 자동표적추출 시스템을 분석하고 구현하였다. 구현된 자동표적추출 시스템을 MSTAR 데이터 셋을 이용하여 실험하여 결과를 도출하고， 그 결과를 분석하여 자동표적추출 시스템 각 단계의 성능을 분석하였다. 분석 결과 각 단계별로 최적의 성능을 보여주는 임계값을 알아낼 수 있었다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.369-371
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• 2017

지반침하는 열차 탈선과 같은 대형재난을 야기할 수 있다. 그러므로 지반침하를 사전에 파악하기 위한 다양한 연구가 진행 중이다. 최근 광범위한 지역의 지표변위를 경제적으로 분석할 수 있는 InSAR(nterferometric SAR)기법을 이용한 연구가 활발히 진행되고 있다. InSAR 기법 중 PS-InSAR(Permanent Scatterer Interferometric SAR)기법이란 SAR영상에서 긴밀도가 높은 고정산란체(PS:Permanent scatterer)를 이용하여 지반침하를 분석하는 기법으로 다른 InSAR 기법에 비해 대기에 의해 발생하는 오차가 적으며, 보다 정확한 지표변위량을 도출할 수 있다. 또한 장기간에 걸친 시계열적 지표 변위 분석에 용이하다. 본 논문에서는 독일의 Terra SAR-X 위성 영상을 이용하여, 광주광산구의 지표변위를 분석하였다. 연구지역인 광주 광산구는 대표적인 연약지반인 평야지역에 위치해 있으며, 실제로 2015년 한국시설안전공단의 발표에 의하면 6곳의 지반탐사 필요 의심지역이 존재할 만큼 지반이 불안정한 지역이다. 연구 결과 광주 광산구 8mm/year로 지반이 침하되고 있음을 알 수 있었다. 이에 광주 광산구 일대의 지반침하 대비를 위해 다양한 노력들이 필요할 것으로 사료된다.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.12-21
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• 2021

For successful automatic target recognition(ATR) with synthetic aperture radar(SAR) imagery, SAR target images of the database should have the identical or highly similar resolution with those collected from SAR sensors. However, it is time-consuming or infeasible to construct the multiple databases with different resolutions depending on the operating SAR system. In this paper, an approach for resolution conversion of SAR target images is proposed based on conditional generative adversarial network(cGAN). First, a number of pairs consisting of SAR target images with two different resolutions are obtained via SAR simulation and then used to train the cGAN model. Finally, the model generates the SAR target image whose resolution is converted from the original one. The similarity analysis is performed to validate reliability of the generated images. The cGAN model is further applied to measured MSTAR SAR target images in order to estimate its potential for real application.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.1
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• pp.49-60
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• 2012

Synthetic aperture radar (SAR) has been employed in various fields due to its capability to generate high resolution images regardless of weather and visibility. This paper presents a performance analysis on the image formation of high resolution SAR according to various slant range distance and synthetic aperture lengths using a range migration algorithm simulator. Although the visual performance on the SAR image is more accurate, a numeric analysis resulted in a comparable measurement. More specifically, raw data were generated for an ideal point target upon imaging geometries and design parameters such as slant range distance and synthetic aperture lengths. Finally, spatial resolution, peak to sidelobe ratio and integrated sidelobe ratio are drawn to provide SAR capabilities in the initial concept design, final in-flight calibration and validation stages.