• Title/Summary/Keyword: Wide Swath

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Ultimate Transverse Bending Strength Analysis of a SWATH Ship (SWATH선의 최종 횡굽힘강도 해석)

  • 박치모
    • Journal of Ocean Engineering and Technology
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    • v.6 no.2
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    • pp.103-112
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    • 1992
  • The calculation method which takes into account the shear lag effects on the ultimate transverse bending moment of a SWATH(Small Waterplane Area Twin Hull) ship has been developed. In case of the ultimate bending strength analysis of conventional monohull ships and general box girder structures, the hypothesis that plane section remains plane after bending can be employed but not in the case of the structures having wide flange. For the ultimate bending strength analysis of such structures, a new method which can take into account the effect of shear lag on the ultimate bending strength has been developed by adopting more reasonable assumption that warping distortion of the section takes place inthe same way as the actual stress distribution. Finally, the proposed method has been applied to a a SWATH cross deck structure.

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A Modified SweepSAR Mode with Dual Channels for High Resolution and Wide Swath

  • Yoon, Seong Sik;Lee, Jae Wook;Lee, Taek-Kyung;Ryu, Sang-burm;Lee, Hyeon-Cheol;Lee, Sang Gyu
    • Journal of electromagnetic engineering and science
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    • v.18 no.3
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    • pp.199-205
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    • 2018
  • In this study, an imaging mode of the modified SweepSAR is proposed with performance analysis for a high-resolution and wide swath coverage. To reduce the overall antenna size required for the solution of the azimuth ambiguity problem, different pulse repetition frequencies (PRFs) are utilized for different transmitters, respectively. For each imaging mode, system performance parameters are used for simulation, analysis, wide swath prediction, and comparison between conventional ScanSAR mode and SweepSAR mode based on scanon-receive (SCORE). The system parameters of AASR, RASR, and NESZ will be estimated and suggested on the imaging mode by using appropriate reflector antenna with the effectiveness of a modified SweepSAR employing dual channels.

Current Trends of the Synthetic Aperture Radar (SAR) Satellite Development and Future Strategy for the High Resolution Wide Swath (HRWS) SAR Satellite Development (SAR(Synthetic Aperture Radar) 위성 개발현황 및 향후 HRWS(High Resolution Wide Swath) SAR 위성 개발전략)

  • Ko, Ungdai;Seo, Inho;Lee, Juyoung;Jeong, Hyunjae
    • Journal of Space Technology and Applications
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    • v.1 no.3
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    • pp.337-355
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    • 2021
  • This paper is made to suggest a future strategy for the Korean High Resolution Wide Swath Synthetic Aperture Radar (HRWS SAR) satellite development by surveying the current trends for the SAR satellite technologies. From the survey, the latest SAR technology trends are revealed of using Digital Beam-Forming (DBF), SCan-On-Receive (SCORE), Displaced Phase Center Antenna (DPCA), interferometry, and polarimetry for exploiting the SAR imagery. Based on the latest SAR technology trends and the foreign HRWS SAR development cases, the strategy for the future HRWS Korean SAR satellite development is suggested to develop the DPCA and SCORE technologies by using the KOrea Multi-Purpose SATellite-6 (KOMPSAT-6) which is going to launch in a few years, and consequently to develop the HRWS SAR satellites which can monitor the whole Earth at weekly intervals.

Performance Analysis of Quad-pol SAR System for Wide-Swath Operation Mode (광역관측 운용 모드에 대한 Quad-pol SAR 시스템의 성능 분석)

  • Lim, Jung-Hwan;Yoon, Seong Sik;Lee, Jae-Wook;Lee, Taek-Kyung;Ryu, Sang-Burm;Lee, Hyeon-Cheol;Lee, Sang-Gyu
    • 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.

Multiple Noise OFDM Waveforms for Wide Swath MIMO SAR (광역 MIMO SAR 영상 획득을 위한 다중 잡음 OFDM 파형 활용 연구)

  • Moon, Minjung;Song, Kyungmin;Lee, Wookyung;Ryu, Sang-Burm;Lee, Hyeon-Cheol;Lee, Sang-Gyu
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.6
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    • pp.464-472
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    • 2018
  • Future spaceborne satellite synthetic aperture radar(SAR) system is expected to acquire high-resolution images over wide swath areas. Conventional SAR systems suffer from ambiguity problems in both azimuth and range directions that lead to image quality degradation. Recently, multiple input multiple output(MIMO) SAR techniques having multiple orthogonal waveforms are proposed to overcome the conventional ambiguity problems in wide-swath imaging modes. In this paper, noisy orthogonal frequency division multiplex(OFDM) waveforms are developed to reduce the ambiguity problems and suppress the image quality degradation. SAR simulations are performed to evaluate the performance of the proposed technique for wide-swath SAR imaging.

Design Technique for Wide Swath SAR TOPS imaging Mode (광역관측을 위한 영상레이더 TOPS 모드 설계 기법)

  • Kim, Se-Young;Sung, Jin-Bong;Yi, Dong-Woo;Shim, Sang-Heun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.5
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    • pp.466-471
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    • 2015
  • In this paper, the design technique of the wide swath TOPS(Terrain Observation by Progressive Scan) imaging mode is introduced. The TOPS mode overcomes the scalloping limitations imposed by ScanSAR mode by steering the antenna pattern along track direction during the acquisition of a burst. This paper reports the operation concept of TOPS imaging and mode design result to extract the SAR operational parameters. Finally, several analyzed results such as IRF(Impulse Response Function), NESZ(Noise Equivalent Sigma Zero) and DTAR(Distributed Target Ambiguity Ratio) are presented.

System Performance Analysis for Multi-Band SweepSAR Operating Mode (다중대역 SweepSAR 운용 모드의 시스템 성능 분석)

  • Yoon, Seong-Sik;Lee, Jae-Wook;Lee, Taek-kyung;Ryu, Sang-Burm;Lee, Hyeon-Cheol;Kang, Eun-Su;Lee, Sang-Gyu
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.3
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    • pp.186-194
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    • 2017
  • In this paper, we analyze the main performance of satellite's Synthetic Aperture Radar system for high resolution and wide swath. We have used the radiation pattern of reflector antenna with array feed and comparison between the conventional ScanSAR mode and SweepSAR mode has been carried out. The SweepSAR mode is a high-resolution wide-swath mode that transmits beams over a wide range and receives echo signals through sequential beamforming based on SCORE(SCan On REceive). In this paper, we analyzed the operating principle and characteristics of satellite's SweepSAR mode and simulate system performances. In addition, in order to increase the utilization of image, performances analysis for multiple frequency bands(C-band, X-band) has been considered.

Performance Analysis in Wide Swath Mode on a Spaceborne SAR System (위성탑재 영상레이다(SAR)의 광역감시 모드에 대한 체계 성능 분석)

  • 이범석
    • Journal of the Korea Institute of Military Science and Technology
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    • v.4 no.1
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    • pp.104-123
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    • 2001
  • Synthetic Aperture Radar(SAR) can provide radar imagery in all weather, day and night situations. Recently SAR system consisted of several imaging modes, has been used for not only military purpose, but also commercial and scientific applications. This paper firstly reviews spaceborne SAR theory, specially scansar principle, and secondly the theories and the design procedures of system performance analysis in the scansar mode, which are different from the ones in the conventional stripmap mode. Based on the SAR-related knowledge, it lastly derives the results of performance analysis in wide swath mode using the scansar technique at the design phase. It shows that these results can meet the system requirements as given the customer. In future, they will continuously be updated using the real measurement data, in connection with the development of a spaceborne SAR system.

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SPACEBORNE TOPS SAR SYSTEM MODELING AND PERFORMANCE ANALYSIS (TOPS 위성 SAR 모드 시스템 구현 및 성능 평가 연구)

  • Kang, Seo-Li;Song, Jeong-Hwan;Kim, Bum-Seung;Kim, Hyeon-Cheol;Lee, Woo-Kyung
    • Journal of Satellite, Information and Communications
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    • v.9 no.2
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    • pp.74-79
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    • 2014
  • Conventional ScanSAR mode has been adopted in Envisat or Radarsat and played an important role to acquire wide swath SAR images for environmental surveillance. However, it suffers from the undesirable scalloping effect caused by non-homogeneity of antenna pattern while the image resolution is sacrificed. In recent years, TOPS mode has been suggested and put into use to overcome the disadvantages of the conventional scanning mode. Although TOPS mode is able to produce wide-swath SAR image in a short time interval, it demands highly complicated system design knowledge. In this paper, we present the operation principle of TOPS mode and a full SAR simulation is performed to generate TOPS SAR raw data. Azimuth antenna pattern is modified during TOPS mode operation and it is shown that the undesired scalloping effect is suppressed in the generated SAR image.

An Efficiency Assessment for Reflectance Normalization of RapidEye Employing BRD Components of Wide-Swath satellite

  • Kim, Sang-Il;Han, Kyung-Soo;Yeom, Jong-Min
    • Korean Journal of Remote Sensing
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    • v.27 no.3
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    • pp.303-314
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    • 2011
  • Surface albedo is an important parameter of the surface energy budget, and its accurate quantification is of major interest to the global climate modeling community. Therefore, in this paper, we consider the direct solution of kernel based bidirectional reflectance distribution function (BRDF) models for retrieval of normalized reflectance of high resolution satellite. The BRD effects can be seen in satellite data having a wide swath such as SPOT/VGT (VEGETATION) have 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 when applying semi-empirical model. This gives a difficulty to run BRDF model inferring the reflectance normalization of high resolution satellites. The principal purpose of the study is to estimate normalized reflectance of high resolution satellite (RapidEye) through BRDF components from SPOT/VGT. We use semi-empirical BRDF model to estimated BRDF components from SPOT/VGT and reflectance normalization of RapidEye. This study used SPOT/VGT satellite data acquired in the S1 (daily) data, and within this study is the multispectral sensor RapidEye. Isotropic value such as the normalized reflectance was closely related to the BRDF parameters and the kernels. Also, we show scatter plot of the SPOT/VGT and RapidEye isotropic value relationship. The linear relationship between the two linear regression analysis is performed by using the parameters of SPOTNGT like as isotropic value, geometric value and volumetric scattering value, and the kernel values of RapidEye like as geometric and volumetric scattering kernel Because BRDF parameters are difficult to directly calculate from high resolution satellites, we use to BRDF parameter of SPOT/VGT. Also, we make a decision of weighting for geometric value, volumetric scattering value and error through regression models. As a result, the weighting through linear regression analysis produced good agreement. For all sites, the SPOT/VGT isotropic and RapidEye isotropic values had the high correlation (RMSE, bias), and generally are very consistent.