• Korean Journal of Remote Sensing
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• v.21 no.2
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• pp.145-162
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• 2005

To improve the accuracy of land-cover discrimination in SAB data classification, this paper presents a methodology that includes feature extraction and fusion steps with multi-temporal SAR data. Three features including average backscattering coefficient, temporal variability and coherence are extracted from multi-temporal SAR data by considering the temporal behaviors of backscattering characteristics of SAR sensors. Dempster-Shafer theory of evidence(D-S theory) and fuzzy logic are applied to effectively integrate those features. Especially, a feature-driven heuristic approach to mass function assignment in D-S theory is applied and various fuzzy combination operators are tested in fuzzy logic fusion. As experimental results on a multi-temporal Radarsat-1 data set, the features considered in this paper could provide complementary information and thus effectively discriminated water, paddy and urban areas. However, it was difficult to discriminate forest and dry fields. From an information fusion methodological point of view, the D-S theory and fuzzy combination operators except the fuzzy Max and Algebraic Sum operators showed similar land-cover accuracy statistics.

• 한국지구과학회:학술대회논문집
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• 2005.09a
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• pp.79-84
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• 2005

이 논문에서는 구름과 같은 기상 상태의 제약 없이 자료 획득이 가능한 SAR 자료를 이용하여 토지 피복 특성을 구분하고자 하였다. 기존 단일 주파수, 편광 상태의 자료만을 제공하는 SAR 자료를 이용한 분류에서의 낮은 분류 정확도를 향상시키고자 이 논문에서는 다중 시기 C 밴드 자료이면서 서로 다른 편광 상태의 자료를 제공하는 Radarsat-1(HH)와 ENVISAT(VV) 자료를 분류에 이용하였다. 분류 기법으로 Random Forests를 적용한 결과, 단일 편광 상태의 자료만을 이용하였을 때에 비해서 보다 향상된 분류 정확도를 얻을 수 있었다.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.47-52
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• 2004

Interferometric synthetic aperture radar (InSAR) is a remote sensing technique capable of measuring ground surface deformation with sub-centimeter precision and spatial resolution in tens-of-meters over a large region. This paper highlights our on-going investigations of Aleutian volcanoes with SAR images acquired from European ERS-1 and ERS-2, Canadian Radarsat-l, and Japanese JERS-l satellites.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.155-168
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• 1996

Speckle noise has been a primary concern to many applications of synthetic aperture radar (SAR) imagery. In recent years, several satellites with radar imaging systems were launched and the use of SAR data are expected to be increased rapidly The objectives of this study are to provide introductory understanding on radar speckle filtering and to compare the effects of several filtering methods that are relatively unknown to user community. Two study sites were extracted from the RADARSAT SAR data obtained over the suburban areas near Seoul. The study sites include relatively homogeneous cover types, such as reservoir, parking lot, rice pad, and deciduous forest. Five filters (mean filter, median filter, sigma filter, local statistics filter, and autocorrelation filter) were applied to the SAR imagery and their effects were evaluated from the aspects of both image smoothing and edge preservation. In overall, the evaluation results indicate that the local statistics filter and autocorrelation filter, that are based on a speckle model, are more effective to suppress speckle within homogeneous cover type while maintaining the edge sharpness between cover types.

• Proceedings of the International Union of Geodesy And Geophysics Korea Journal of Geophysical Research Conference
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• 2003.05a
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• pp.14-14
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• 2003

SAR (Synthetic Aperture Radar) is an imaging radar which can scan and image Earth System targets without solar illumination. Most Earth observation Shh systems operate in X-, C-, S-, L-, and P-band frequencies, where the shortest wavelength is approximately 1.5 cm. This means that most opaque objects in the SAR signal path become transparent and SAR systems can image the planetary surface targets without sunlight and through rain, snow and/or even volcanic ash clouds. Most conventional SAR systems in operation, including the Canada's RADARSAT-1, operate in one frequency and in one polarization. This has resulted in black and with images, with which we are familiar now. However, with the launching of ENVTSAT on March 1 2002, the ASAR system onboard the ENVISAT can image Earth's surface targets with selected polarimetric signals, HH+VV, HH+VH, and VV+HV. In 2004, Canadian Space Agency will launch RADARSAT-II, which is C-band, fully polarimetric HH+VV+VH+HV. Almost same time, the NASDA of Japan will launch ALOS (Advanced land Observation Satellite) which will carry L-band PALSAR system, which is again fully polarimetric. This means that we will have at least three fully polarimetric space-borne SAR system fur civilian operation in less than one year. Are we then ready for this new all weather Earth Observation technology\ulcorner Actual imaging process of a fully polarimetric SAR system is not easy to explain. But, most Earth system scientists, including geologists, are familiar with polarization microscopes and other polarization effects in nature. The spatial resolution of the new generation of SAR systems have also been steadily increased, almost to the limit of highest optical resolution. In this talk some new applications how they are used for Earth system observation purpose.

• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.257-272
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• 2007

This paper analyzed relationships between various features from SAR data with multiple acquisition dates and mode (frequency, polarization and incidence angles), and land-cover classes. Two typical types of features were extracted by considering acquisition conditions of currently available SAR data. First, coherence, temporal variability and principal component transform-based features were extracted from multi-temporal and single mode SAR data. C-band ERS-1/2, ENVISAT ASAR and Radarsat-1, and L-band JERS-1 SAR data were used for those features and different characteristics of different SAR sensor data were discussed in terms of land-cover discrimination capability. Overall, tandem coherence showed the best discrimination capability among various features. Long-term coherence from C-band SAR data provided a useful information on the discrimination of urban areas from other classes. Paddy fields showed the highest temporal variability values in all SAR sensor data. Features from principal component transform contained particular information relevant to specific land-cover class. As features for multiple mode SAR data acquired at similar dates, polarization ratio and multi-channel variability were also considered. VH/VV polarization ratio was a useful feature for the discrimination of forest and dry fields in which the distributions of coherence and temporal variability were significantly overlapped. It would be expected that the case study results could be useful information on improvement of classification accuracy in land-cover classification with SAR data, provided that the main findings of this paper would be confirmed by extensive case studies based on multi-temporal SAR data with various modes and ground-based SAR experiments.

• Korean Journal of Remote Sensing
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• v.25 no.3
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• pp.243-253
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• 2009

For the last 14 years, space-borne satellite SAR system such as RADARSAT-1, ERS-2, and ENVISAT ASAR have provided a continuous observation over the ocean. However, the data acquired from those systems were limited to C-band frequency until the advent of the first spacebome German X-band SAR system TerraSAR-X in 2007. Korea is also planning to launch the nation's first X-band SAR satellite (KOMPSAT-5) in 2010. It is timely and necessary to develop X-band models for estimating geophysical parameters from these X-band SAR systems. In this study, X-band wind retrieval model was investigated and developed based on numerical ocean scattering model (radar backscattering model and hydrodynamic interaction model). Although these models have not yet been tested and validated for broad ranges of wind conditions, the estimated wind speeds from TerraSAR-X data show generally good agreement with in-situ measurements.

• Proceedings of the KSRS Conference
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• 2001.03a
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• pp.9-14
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• 2001

오랜 기간동안 진행되는 사회간접자본 건설의 진행 상황을 관측하는 것은 대규모 공사의 종합적인 관리를 위해 필수불가결한 요소이다. 동북아 지역의 중추 공항 기능을 담당할 영종도 국제공항의 공사진행 과정을 관측하기 위하여 인공위성 영상 자료가 활용되었다. 바다위에 건설되는 공항의 특성으로 인하여 방조제 건설과 매립공사가 수행되었다. 활주로, 유도로, 여객터미널과 복합교통센터 등이 건설되었으며, 공항의 건설로 산림이 훼손되고 양식장과 염전이 매립되는 것이 관측되었다. 이러한 공항공사의 진척상태를 분석하기 위해서 시계열 Landsat TM 영상을 사용하였으며, 타 위성영상에서는 공항의 공사현황이 어느정도 분석가능한지를 가늠하기 위해서 KOMPSAT EOC, IRS-1C PAN, RADARSAT SAR 영상이 활용되었다. 시계열 Landsat TM 영상에서는 공항 부지의 매립 진척 현황과 산림의 벌채 등을 잘 분석할 수 있었다. KOMPSAT EOC 과 IRS-1C PAN 영상은 높은 공간해상력으로 건설에 사용된 가건물과 같은 세부적인 시설물을 관측할 수 있었다. 15m PAN 영상을 제공하는 Landsat ETM은 IHS 합성 후 분석하였는데, 기존의 TM 영상에서 분류하지 못했던 방조제의 도로와 성토를 구분할 수 있었다. RADARSAT SAR 영상에서는 광학영상에서 볼 수 없었던 독특한 정부 를 얻을 수 있었다.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.757-759
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• 2003

Understanding the area of the rice paddy fields is important, and suitable for it the remote sensing. SAR is effective to the monitor in Southeast Asia with the rainy season. The detection of the filled rice paddy fields by RADARSAT was tried in the north part of Bangkok Thailand, and in the Mekong river valley Cambodia, which ware the main rice production country in Southeast Asia. We get observation data by RADARSAT and fields all through a year around Bangkok. However, because the flood had occurred on the study area in 2002 observed, the detection only of the rice fields ware difficult.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.303-308
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• 2004

The acquisition of many control points for SAR data processing is very difficult and time_consuming steps. For resolving the problem about control points, this paper describes satellite orbit refinement method using minimum control point. Accuracy of geocoding according to distribution and number of control points are analyzed and geocoded RADARSAT image was produced in the paper.