• Korean Journal of Remote Sensing
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• v.21 no.6
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• pp.483-491
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• 2005

SAR signal processing technique has been considered a crucial technical part in order to generate an image from radar signal data and ADD (Agency for Defense Development) has focused on this area for years to develope our own SAR Processor for various SAR systems (Radarsat, ERS, KOMSAR). In this paper, we investigated major techniques related to generation of SAR images and developed ASPR (ADD SAR Processor for Radarsat) practically using the commercial Radarsat-1 radar signal data (RAW). We demonstrated the performance of the ASPR in comparison with the image generated by MDA and Vexcel's SAR Processor (FOCUS).

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.309-313
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• 2009

산불은 전세계적으로 발생하는 가장 주요한 재해현상 중 하나이다. 산불 감시나 산불에 의한 피해지역의 효과적인 관측은 피해 지역을 최소화하고, 효율적인 피해 복구 계획 수립에 매우 중요한 기초자료를 제공한다. 광학 위성 자료를 활용한 산불 피해지역 탐지가 널리 사용되고 있음에도 불구하고, 산불에 의한 연기 또는 구름 분포에 의해 종종 사용상에 제약이 있다. 본 연구에서는 2000년 4월 강원도 고성, 강릉, 삼척, 물진 지역에서 발생한 대규모 산불을 연구 대상지역으로 하여, 1998년-2000년 동안 획득된 RADARSAT-1 SAR 영상을 이용하여 산불 피해 지역 감시의 활용성을 연구하였다. 산불에 의한 산림 피해지역 관측을 위해 RADARSAT-1 SAR 영상의 후방산란관의 변화를 통한 변환 탐지를 수행하였다. 산불 피해지역에서 산불 전에 비해 산불 후에 획득된 RADARSAT-1 SAR 영상의 후방산란값이 증가하는 것으로 관측되었다. RADARSAT-1 SAR 영상으로부터 관측된 산불 피해 지역은 Landsat-7 ETM 자료와 현장 조사 자료에 의한 산불 피해 지역과 매우 상관성이 높은 것으로 관측되었다.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2002.10a
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• pp.195-199
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• 2002

SAR(Synthetic Aperture Radar) 영상은 경사촬영을 수행하므로 지형의 기복에 따른 영향을 많이 받는다. 따라서 SAR영상을 이용하여 여러 가지 정보들을 추출하여 이용하기 위해서는 전처리 과정으로서 지형의 기복에 따른 여러 가지 왜곡들을 보정해야 한다. 이에 본 연구에서는 RADARSAT SAR 영상을 이용하여 궤도모델링, 정사보정을 수행하고 역산란계수, 국부입사각 계산 등을 통해 지형기복에 따른 방사왜곡보정을 수행하였다.

• Korean Journal of Remote Sensing
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• v.14 no.1
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• pp.69-82
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• 1998

SAR imagery can overcome the limitations of electro-optical sensor imagery and provide us Information which plays a supplementary role. But it is necessary to remove a variety of geometric errors in SAR imagery. An accurate geometric correction of SAR imagery is not easy task to achieve, though some techniques and theories are introduced. We also have difficulties such as transformation problem between 'International' ellipsoid in Radarsat system and 'Bessel' ellipsoid. Two widely used correction method, one is made by simulated image, and the other by collinearity equation, usually use DEM. In this study, the merits and demerits of geocoding methods respectively and the effective method for Korean terrain were found.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.605-612
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• 2010

Numberous satellites have monitored the Earth in order to detect changes in a large area. These satellites provide orbit information such as ephemeris data, RPC coefficients and etc. besides image data. If we can use such orbit data afforded by satellite, we can reduce the number of control point for geo-referencing. This paper shows the efficient geometric correction method of strip-satellite RADARSAT-l SAR images acquired by same orbit using ephemeris data, single control point and virtual control points. For accuracy analysis of proposed method, this paper compared the image geometrically corrected by the proposed method to the image corrected by ERDAS Imagine.

• Korean Journal of Remote Sensing
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• v.14 no.4
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• pp.325-342
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• 1998

Two RADARSAT SAR images with different modes acquired by Canadian Space Agency to test the effectiveness of geological lineament extraction and spring water detection over the Cheju Island. Geological lineaments are poorly developed this basalt dominant volcanic island, but more linear features can be extracted when SAR and TM images are simultaneously analyzed than when TM image alone is used. This results mainly owe to the facts that RADARSAT SAR systems are able to provide data with different frequencies, azimuth, and incidence angles. Distribution of spring water along coast is poorly correlated with geological lineaments or drainage pattern, but those in middle range of mountain region are developed along geological lineaments. Detection of spring water using remotely sensed images are turned out to be very difficult to achieve. Radial shaped sea surface temperature anomaly derived from TM thermal band should be the best candidate for spring water, but the resolution is not high enough. We also investigate the normalized radar cross section (or sigma naught) converted from RADARSAT and ERS-1 SAR data but to discriminate the spring water effectively except where relatively large water mass is observed on land side. Speckle noise and irregularity in physical sea surface condition are the serious obstacles for this application. ERS-1 SAR image acquired in low incidence angle was more useful for geological lineament estimation and water body study than RADARSAT SAR images with high incidence angles. Therefore the selection of incidence angle is critical in geological and spring water applications of SAR images, and low incidence angles less than about 30$^{\circ}$ are recommended to monitor the Cheju volcanic island.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.596-601
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• 2003

위성영상으로부터 수계영역을 분류하는 일은 홍수관련 분석을 위해서 매우 중요한 일이다. 본 연구에서는 홍수 발생시 취득된 RADARSAT 영상을 이용해서 산악지역의 수계영역의 분류를 목적으로 하였다. SAR 영상은 능동적 영상취득을 수행하므로 광학영상에 비해서 수계영역이 확실하게 나타나는 반면에 지형의 기복에 따른 여러 가지 왜곡현상이 발생한다. 본 연구에서는 RADARSAT 영상으로부터 수계영역의 분류를 위해 방사보정, 그림자 효과제거, 고도자료 및 경사도 자료의 활용 등의 경우로 구분하여 연구를 수행하였다. 그 결과 RADARSAT 영상만을 활용할 경우 분류의 정확도에 한계를 보였으며, RADARSAT 영상에 지형정보를 추가로 활용함으로서 정확한 수계영역을 분류할 수 있었다. 특히 RADARSAT 영상과 경사도 자료를 동시에 활용하여 수계지역을 분류하는 것이 가장 효과적임을 알 수 있었다.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.75-78
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• 2006

이 연구에서는 Radarsat-1 SAR 영상과 조위자료, 증발자료 및 다편광 산란계를 이용한 개펄 건조 실내실험 등을 통하여 해수면 위로 노출된 자연갯벌이 증발과 구조적 변화를 일으킬 때 레이더 후방산란계수의 변화를 분석하였다. 개펄 건조 실내실험 결과, 후방산란계수가 증발시간에 따라 단순한 증가나 감소를 보이지 않았으며 갯벌의 구조와 배수, 증발, 건조 등에 의해 보다 복잡한 M자 형태(증가-감소-증가-감소)의 변화를 나타내었다. 이러한 M형의 변화는 증발시간에 따른 Radarsat-1 SAR 15개 영상의 후방산란계수 변화 양상에서도 나타나는 것으로 확인되었다.

• Korean Journal of Remote Sensing
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• v.15 no.1
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• pp.61-71
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• 1999

Several physical phenomena on the sea surface are analyzed from SAR images of South Sea areas, Korea. Strong wave patterns propagating in southerly direction are seen in ERS-1 SAR image on October 11, 1994, and a wave directional spectrum is calculated from this image using the SAR modulation transfer function. RADARSAT SAR image of August 15, 1996 reveals internal waves in northern coastal waters of Cheju Island. Analysis indicates that the internal waves may have been generated by the tidal currents traveling over the shallow bottom of the stratified water in the summer during the tidal changeovers fro ebb to flood and shows patterns of trains of solitons. RADARSAT SAR image taken 3 days after the oil spill accident near Goeje Isalnd on April 3, 1997 detects distinct oil slicks from the accident area but also shows slicks near the coast caused by wind sheltering of coastal mountains and chemical-biological activities.

• Journal of Korea Water Resources Association
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• v.39 no.11 s.172
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• pp.969-976
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• 2006

The purpose of this study is to trace the flood inundation area around rural small stream by using RADARSAT image because it has the ability of acquiring data during storm period irrespective of rain and cloud. For the storm August 9, 1998 in the Anseong-cheon watershed, three RADARSAT images before, just after and after the storm were used. After ortho-rectification using 5 m DEM, two methods of RGB composition and ratio were tried and found the inundated area in the tributary stream, the Seonghwan-cheon and the Hakjeong-cheon. The inundated area had occurred at the joint area of two streams, thus the floodwater overflowed bounding discharge capacity of the stream. The progression of damage areas were stopped by the local road and farm road along the paddy. The result can be used to acquire the flood inundation data scattered as a small scale in rural area.