• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.69-70
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• 2019

본 논문에서는 토지 정보를 분류하는 연구를 수행하기 위한 이미지 데이터 셋을 개발하는데 필요한 반자동 annotation 도구를 제안한다. 논문에서 제안하는 도구는 합성개구레이더 영상을 입력으로 하고, 물/경작지/숲/건물을 구분하는 시스템을 개발하기 위해서 만들어진 것이나, 다른 목적을 가지는 토지 관련 이미지 분석 시스템의 개발에 사용될 수 있다. 제안하는 도구는 합성개구레이더 영상이 GPS 정보와 같이 입력되었을 때, GPS 정보에 기반하여 토지지목정보를 불러오고, 이를 재정리하여 1차 레이블링 결과를 자동적으로 생성한다. 국가에서 관리하는 토지지목정보는 개발하고자 하는 시스템의 분류 기준에 많은 부분 도움이 되긴 하지만, 일부분 차이점이 있기 때문에 이를 다시 수동으로 수정하는 도구을 동작하여 annotation이 완료된 이미지 데이터를 구축한다.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.11
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• pp.123-132
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• 1998

This paper presents a road detection technique for spaceborne synthetic aperture radar (SAR) images. Roads are important cartographic features. We incorporate an active contour model called snake as a model for the road and define a new external energy for snake which is appropriate for the road. Detecting roads in spaceborne SAR images is very difficult without other information. In this paper, digital maps are utilized to obtain the initial position and shape for snake. Only approximate geodetic location of roads appearing in SAR images can be known through geocoding process and usual digital maps also have location errors. Therefore, there exist large location offsets between the two data. By introducing initial matching procedure, the errors are reduced significantly. Then we initialize the snake's shape using the roads extracted from digital map and minimize the energies of all snake points to detect roads. We outline two problems in detection and propose a method that mitigates them.

• Current Industrial and Technological Trends in Aerospace
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• v.3 no.1
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• pp.65-71
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• 2005

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1175-1184
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• 2008

Delay-sum back projection(DSBP) algorithm and the time reversal algorithm based on the finite-difference time-domain method are compared. The two algorithms, which operate in the time domain, can process the ultra-wideband (UWB) radar data to generate images that are close to the original location and shape of the target. For the experiment, the UWB radar consists of a network analyzer, a resistive V dipole antenna, a scanner, and a control computer. The radar aperture is synthesized by linearly scanning the antenna. A calibration procedure is applied to the measured data to remove signal distortion and clutter. The two algorithms are applied to the same data on the same platform. It is shown that the DSBP algorithm produces better images but takes longer time to produce the images than the FDTD-TR algorithm.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.602-605
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• 2006

Locating reinforcing bars, in particular to know their accurate depths and horizontal distances, is very important in radar inspection of concrete structures. By the way, it is not easy for an accurate depth and horizontal distance estimation of reinforcing bars in concrete structures by the radar test. This problem can be solved by synthetic aperture radar method. To improve the vertical and horizontal resolution of reinforcing bars in concrete, synthetic aperture radar method was examined in this study.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.53-56
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• 2010

Oil spills and red tide can be very damaging to the environment and fishery farming. These catastrophic accidents must be detected as quickly as possible. In this paper, we report the results of applying the wavelet transform to SAR or marine radar images for the detection of the boundaries of an oil spill or red tide. The application of the wavelet transform to these phenomena looks quite promising in detecting the boundaries of oil spills and red tide areas.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.193-200
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• 2024

This paper describes the design and development of a transmit receiver module(TRM) for mounting on X-band SAR of the NEXTSat-2. The TRM generates the chirp signal with required bandwidth through the DDS in X-band and performs frequency conversion, combination for the signal to transmit and be received and frequency synthesis. Tx path of the TRM produces signals of total 28 bandwidths up to 96.8 MHz and has output signal level of more than + 9.37 dBm. Rx path of the TRM has minimum noise figure of 15.7 dB. The measurement results show that required requirements are satisfied. The TRM is installed on the NEXTSat-2 flight model(FM), launched by KSLV-II(Nuri) on May 23, 2023 and currently operational.

• Korean Journal of Remote Sensing
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• v.23 no.6
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• pp.501-506
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• 2007

Basic research is conducted to identify a target using corner reflectors which are commonly used in calibration of synthetic aperture radar (SAR) systems. At first, an omni-directional reflector is fabricated by combining four 15-cm rectangular trihedral corner reflectors. Then, its radar cross section (RCS) characteristics are measured at C-band (5.3 GHz) for vv-, hh-, hv-, and vh- polarizations at a range of horizontal angle, $-90^{\circ}{\le}{\phi}{\le}90^{\circ}$. The measured RCS angular variation of the omni-directional reflector is much smaller for vv-polarization than other polarizations, and the difference between the maximum and minimum RCSs for vv-polarization is about 8 dB. Peak RCS values are shown at $0^{\circ}$ (normal to plates) and $45^{\circ}$ (direction of bore sight). It is shown that the measurements agree quite well with numerical simulation and theoretical computation results.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.25.1-25.1
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• 2011

다목적 실용위성 5호는 국내 최초로 합성 개구면 레이더(SAR)를 장착한 지구 관측위성으로서 2011년 중반에 러시아의 Dnepr 로켓에 의해 발사되어 평균 고도 550 km의 태양동기 여명궤도에서 운용될 예정이다. 위성은 28일을 주기로 지구를 421회 공전하는 반복 지상궤적을 가지며 인터페로메트리 레이더 영상의 획득을 위해 위성이 지구적도 상공을 통과할 때 기준경도로부터 ${\pm}2$ km 이내로 지상궤적이 유지될 수 있도록 궤도조정을 수행한다. 위성은 궤도에 투입된 후 2개월 이내에 정상적인 지상궤적을 획득하고 몽골에 설치된 레이더 반사판을 이용하여 4개월에 걸친 검보정을 수행한 후에 정상적인 운용에 들어가게 된다. 이 연구에서는 위성이 발사체와 분리된 이후 정상적인 지상궤적을 획득하는데 걸리는 시간을 분석하고 위성의 지상궤적을 기준 경도로부터 ${\pm}2$ km 이내로 유지시키기 위한 궤도조정에 필요한 조정주기와 연료소모량을 분석한다.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.2
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• pp.98-104
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• 2010

The demand for Satellite Images is continuously increasing owing to the various applications of optical satellite images. However, the acquisition of optical images has a limitation due to problems of weather and day & night. because an optical satellite makes images with reflections of sunlight. Therefore, SAR Satellite, which uses electromagnetic waves to make an image, gives increased demand to various applications. It also makes increased interest. In this paper, a calibration and validation system, which is an essential element for high quality Radar images, is studied.