• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.955-964
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• 2010

In this paper, a compensation method of the amplitude and phase errors from the T/R(Transmit/Receive) modules in an active SAR(Synthetic Aperture Radar) system is introduced. The errors are defined and classified, and characterized by analyzing the measurement data acquired from the pilot test. To compensate these errors, a control methodology of T/R modules output is proposed. Before the compensation is applied, 16 T/R modules integrated on the active SAR antenna show the amplitude in 28.2~29.0 dBm and the phase in $101.7^{\circ}{\sim}165.2^{\circ}$. After the compensation, the amplitude and phase are distributed in 27.4~28.0 dBm and $116.1^{\circ}{\sim}120.0^{\circ}$ respectively. The antenna beam patterns generated by the array theory with the distributions are compared, and the proposed method is verified as good to apply for the active SAR system.

• Korean Journal of Remote Sensing
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• v.35 no.1
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• pp.29-37
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• 2019

Synthetic Aperture Radar (SAR) observations are powerful tools to monitor surface's displacement very accurately, induced by earthquake, volcano, ground subsidence, glacier movement, etc. Especially, radar interferometry (InSAR) which utilizes phase information related to distance from sensor to target, can generate displacement map in line-of-sight direction with accuracy of a few cm or mm. Due to decorrelation effect, however, degradation of coherence in the InSAR application often prohibit from construction of differential interferogram. Offset tracking method is an alternative approach to make a two-dimensional displacement map using intensity information instead of the phase. However, there is limitation in that the offset tracking requires very intensive computation power and time. In this paper, efficiency of parallel computing has been investigated using high performance computer for estimation of glacier velocity. Two TanDEM-X SAR observations which were acquired on September 15, 2013 and September 26, 2013 over the Narsap Sermia in Southwestern Greenland were collected. Atotal of 56 of 2.4 GHz Intel Xeon processors(28 physical processors with hyperthreading) by operating with linux environment were utilized. The Gamma software was used for application of offset tracking by adjustment of the number of processors for the OpenMP parallel computing. The processing times of the offset tracking at the 256 by 256 pixels of window patch size at single and 56 cores are; 26,344 sec and 2,055 sec, respectively. It is impressive that the processing time could be reduced significantly about thirteen times (12.81) at the 56 cores usage. However, the parallel computing using all the processors prevent other background operations or functions. Except the offset tracking processing, optimum number of processors need to be evaluated for computing efficiency.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.132-137
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• 2003

Observations of internal waves in the southwest coastal waters of Korea have been made using a mooring measurement and satellite SAR together. From May 28 to May 30 in 2002, thermistor chains with RCM and ADCP mooring measurements were carried out at 10 kin west of Ocheong-Do, together with a CTD field sur-vey on the surrounding waters. Also, a SAR image was acquired on May 29 at 06:53. The data from the in-situ measurement show several internal wave packets passing through the mooring point and the SAR image reveals numbers of internal wave packets distributed around the point. Temporal and spatial characteristics of internal waves in the southwest coastal waters were analyzed using the data from mooring measurement, SAR image, and the K-dv equation. The internal waves are important phenomena in terms of physical oceanography and military as well as marine biology. They should be considered as one of important features in the southwest coastal waters in summer.