• Proceedings of the KSRS Conference
• /
• v.1
• /
• pp.390-393
• /
• 2006

It is well known that synthetic aperture radar (SAR) provides information on ocean winds and surface waves. SAR data are of particularly high value in extreme weather conditions, as radar is able to penetrate the clouds providing information on different ocean surface processes. In this presentation some recent results on SAR observation of extreme wind and ocean wave conditions is summarised. Particular emphasize is put on the investigation of typhoons and extratropical cyclones in the North Pacific. The study is based on the use of ENVISAT ASAR wide swath images. Wide swath and scansar data are well suited for a detailed investigation of cyclones. Several examples like, e.g., typhoon Talim will be presented, demonstrating that these data provide valuable information on the two dimensional structure of the both the wind and the ocean wave field. Comparisons of the SAR observation with parametric and numerical model data will be discussed. Some limitations of standard imaging models like, e.g., CMOD5 for the use in extreme wind conditions are explained and modifications are proposed. Finally the study summarizes the capabilities of new high resolution TerraSAR-X mission to be launched in October 2006 with respect to the monitoring of extreme weather conditions. The mission will provide a spatialresolution up to 1m and has full polarimetric capabilities.

• Korean Journal of Remote Sensing
• /
• v.26 no.6
• /
• pp.653-664
• /
• 2010

The land surface reflectance is a key parameter influencing the climate near the surface. Therefore, it must be determined with sufficient accuracy for climate change research. In particular, the characteristics of the bidirectional reflectance distribution function (BRDF) when using earth observation system (EOS) are important for normalizing the reflected solar radiation from the earth's surface. Also, wide swath satellites like SPOT/VGT (VEGETATION) permit sufficient angular sampling, but high resolution satellites are impossible to obtain sufficient angular sampling over a pixel during short period because of their narrow swath scanning. This gives a difficulty to BRDF model based reflectance normalization of high resolution satellites. The principal objective of the study is to add BRDF modeling of high resolution satellites and to supply insufficient angular sampling through identifying BRDF components from SPOT/VGT. This study is performed as the preliminary data for apply to high-resolution satellite. The study provides surface parameters by eliminating BRD effect when calculated biophysical index of plant by BRDF model. We use semi-empirical BRDF model to identify the BRD components. This study uses SPOT/VGT satellite data acquired in the S1 (daily) data. Modeled reflectance values show a good agreement with measured reflectance values from SPOT satellite. This study analyzes BRD effect components by using the NDVI(Normalized Difference Vegetation Index) and the angle components such as solar zenith angle, satellite zenith angle and relative azimuth angle. Geometric scattering kernel mainly depends on the azimuth angle variation and volumetric scattering kernel is less dependent on the azimuth angle variation. Also, forest from land cover shows the wider distribution of value than cropland, overall tendency is similar. Forest shows relatively larger value of geometric term ($K_1{\cdot}f_1$) than cropland, When performed comparison between cropland and forest. Angle and NDVI value are closely related.

• Proceedings of the Korea Contents Association Conference
• /
• 2016.05a
• /
• pp.207-208
• /
• 2016

KOMPSAT-5는 마이크로파를 매개로 하는 SAR센서가 탑재되어 있으며 해상도 1m로 기상과 주야간에 관계없이 지상의 영상을 획득할 수 있다. SAR페이로드에는 X-band(9.66GHz)Synthetic Aperture Radar를 포함하고 있다. K5시스템은 Standard Modes, High Resolution Modes와 Wide Swath Modes를 가지고 있으며 4가지의 추가적인 작동모드가 있어 다방면에 활용이 기대된다. 본 연구에서는 KOMPSAT 5 센서재원을 살펴보고 활용방안을 제안하고자 한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.24 no.5
• /
• pp.31-36
• /
• 2024

In this paper, we designed and manufactured an ultra-wide band X-band SAR transceiver to implement HRWS. The manufactured transceiver is designed to operate at a bandwidth of 1500MHz, which results in a distance resolution performance of approximately 26cm at 67degrees incidence angle. To improve IRF performance, which is a performance indicator of wideband SAR signals, pre-distortion was performed for nonlinear distortion. Through predistortion, the PSLR value could be improved -13.13dB and -9.47 ISLR. To verify the de-chirp performance, a wide chirp signal was applied to the receiver's input and local signal. As a results, the -13.5dB PSLR value was confirmed through direct mixing of the chirp signal at the receiver. Through the developed ultra-wideband SAR transceiver technology, it is possible to achieve distance resolution of several tens of centimeters, and it is confirmed that not only direct receiving of wideband chirp signal but also de-chirp signal receiving by mixing wide chirp signal.

• Journal of Advanced Navigation Technology
• /
• v.5 no.2
• /
• pp.149-157
• /
• 2001

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution. It is due to the strict requirement for the real-time data transmission from a series of massive raw image data of spaceborne SAR to the ground station in a limited time of mission. In this paper, based on the data link model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.3
• /
• pp.117-124
• /
• 2002

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution because of the strict requirement for the real-time data transmission of the massive SAR data in a limited time of mission. In this paper, based on the data link model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath. The designed data link module can be effectively used for the spaceborne and airborne applications which requires to expand the high speed data link capability.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1124-1126
• /
• 2003

The processes of regional scales in the East Korean coastal waters were investigated by analysis of the Synthetic Aperture Radar (SAR) images taken by the European Research Satellites ERS-1, ERS-2 and Envisat. More than 500 quick look frames taken in 1991-2003 were examined to detect the frames with clearly surface expressions of oceanic phenomena. 26 ERS-1/2 SAR and 11 Envisat wide swath Advanced SAR (ASAR) frames were selected and obtained from the European Space Agency in a form of the precision high-resolution images. The following oceanic phenomena and processes were evident in the radar imagery through the Korean costal waters: fronts, currents, eddies, internal waves, island and ship wakes, oil pollution, etc. They manifested themselves in the field of sea surface roughness, their scale ranged from several tens meters to about 100 km. The most common morphology of these phenomena was a series of contrast dark or light curvilinear lines and bands. The joint analysis of the discussed SAR images with other satellite and in situ data supported and enhanced our interpretation of SAR signatures.

• Korean Journal of Remote Sensing
• /
• v.23 no.1
• /
• pp.65-69
• /
• 2007

The processes of regional scales in the East Korean coastal waters were investigated by analysis of the Synthetic Aperture Radar (SAR) images taken by the European Research Satellites ERS-1, ERS-2 and Envisat. More than 500 quick look frames taken in 1991-2003 were examined to detect the frames with clearly surface expressions of oceanic phenomena. 26 ERS-1/2 SAR and 11 Envisat wide swath Advanced SAR (ASAR) frames were selected and obtained from the European Space Agency in a form of the precision high-resolution images. The following oceanic phenomena and processes were evident in the radar imagery through the Korean costal waters: fronts, currents, eddies, internal waves, island and ship wakes, oil pollution, etc. They manifested themselves in the field of sea surface roughness, their scale ranged from several tens meters to about 100 km. The most common morphology of these phenomena was a series of contrast dark or light curvilinear lines and bands. The joint analysis of the discussed SAR images with other satellite and in situ data supported and enhanced our interpretation of SAR signatures.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.141-141
• /
• 2019

토양수분은 수문 분석에 있어 매우 중요한 인자 중 하나이며 최근 기후변화로 인한 가뭄, 홍수 및 산불발생과 같은 물 관련 재해 발생에 직 간접적으로 영향을 미치기 때문에 지표 토양수분산정은 매우 중요하다. Sentinel-1 SAR(Synthetic Aperture Radar)는 능동형 위성으로 10m의 공간해상도로 제공되기 때문에 기존의 토양수분 전용위성인 SMOS(Soil Moisure and Ocean Salinity), SMAP(Soil Moisture Active Passive) 및 GCOM-W1(Global Change Observation Mission Water) 등 다르게 고해상도 토양수분 산정이 가능하다. 그러나 Sentinel-1 SAR 센서에서는 고해상도 지표 관측 이미지 자료만 제공하며, 토양수분 자료를 직접적으로 제공하지 않는다. 따라서 본 연구에서는 2018년도 Sentinel-1 A/B IW(Interferometric Wide swath) 모드의 VH(Vertical Transmit - Horizontal Receive) 편파 영상과 Sentinel-1 SAR 위성자료 전처리 도구인 SNAP(Sentinel Application Platform)을 이용하여 후방산란계수를 산정하였으며, 산정된 후 방산란계수와 농촌진흥청에서 제공하는 65개 지점의 실측 TDR(Time Domain Reflectrometry) 토양수분의 관계를 이용하여 회귀모형을 도출 및 토양수분 공간분포를 산정하였다. 비록 불확실성은 어느정도 발생 하였으나, 전체적으로 TDR 관측값과 $10m{\times}10m$ 해상도의 Sentinel-1 SAR 기반 토양수분이 일치하는 경향을 보였다. 본 연구 결과는 수문, 농업, 산림, 재해 등 다양한 분야에 활용될 수 있을 것으로 판단된다.

• Journal of Korean Society for Geospatial Information Science
• /
• v.21 no.2
• /
• pp.3-9
• /
• 2013

Various data like digital maps(1/1,000 or 1/5,000), field surveying, online materials and literatures are used for the preliminary investigation for urban development such as the feasibility evaluation, the profitability analysis, the zoning proposal, the zoning designation, and the land replotting planning. There are a couple of urban development methods like an expropriation, a replotting, a mixed-used method. The replotting method requires the consideration of land replotting types based on topography and building condition, which is not easy to gather data for the preliminary investigation maintaining the security of development planning. There are limitations of a preliminary investigation using aerial photos to detect topographic and building changes at specific period. GIS data combined with high-resolution imagery has advantages over the current dataset, which come from easy acquisition of various spatial resolution satellite images, wide swath coverage, the choice of imagery resolution satisfying a usage purpose, economic benefit comparing to aerial photos, and the calculation of distance and area on imagery from image modeling. For these reasons, the proposed method in this study enables to perform the more appropriate preliminary investigation using more accurate information.