• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.3 s.94
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• pp.335-343
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• 2005

In this paper, we propose a method to classify inverse synthetic aperture radar(ISAR) image from different target. The approach can provide efficient features for classification by the combined use of a polar mapping procedure and a well-designed classifier The resulting feature vectors are able to meet requirements that efficient features should have : invariance with respect to rotation and scale, small dimensionality, as well as highly discriminative information. Typical experimental examples of the proposed method are provided and discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1063-1069
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• 2011

NCTR(Non-Cooperative Target Recognition) and ATR(Automatic Target Recognition) are methodologies to identify military targets using radar, optical, and infrared images. Among them, a strategy to recognize ground targets using synthetic aperature radar(SAR) images is called SAR ATR. In general, SAR ATR consists of three sequential stages: detection, discrimination and classification. In this paper, a modification of the polar mapping classifier(PMC) to identify inverse SAR(ISAR) images has been made in order to apply it to SAR ATR. In addition, a preprocessing scheme can mitigate the effect from the clutter, and information on the shadow is employed to improve the classification accuracy.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.87-89
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• 2007

선행 연구개발한 집단감시 디지털 시스템(Group Digital Surveillance System for Fishery Safety and Security, GDSS- F2S)은 대단위 양식장에 침입하는 도적을 방어하기 위하여 레이더 추적정보와 적아식별 정보를 제공하는 시스템이다. 그러나 GDSS-F2S에서 제공하는 두 가지 정보만으로는 도적행위를 입증할 수 있는 법적 증거자료로 미흡하다. 본 논문에서는 이러한 문제점 해결방안의 하나로 CCD 카메라를 이용한 영상획득 장치를 개발하여 GDSS-F2S에 부가한 연구내용을 기술한다. 영상획득 장치 개발에 앞서, 실험지역의 지리적인 특성을 고려한 도적침입 예상경로 분석과 도적행위 시나리오를 기반으로 유효한 대응수단을 검토한 결과, 영상획득 장치가 유효한 대응수단임을 확인하였다. 영상획득 장치는 저가이변서 성능이 우수한 0.0001 룩스의 초저조도 CCD 카메라와 부가장치를 이용하여 개발하였다. 6개월 이상의 장기 현장실험을 통하여 본 연구에서 개발한 시스템을 평가한 결과, 주간은 물론 1 미터 앞도 식별할 수 없는 야간에도 차량의 행동과 번호판 및 사람의 행동과 인상착의 등의 영상정보를 확보할 수 있었다.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.503-512
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• 2012

We performed DInSAR (Differential Interferometric SAR) and SBAS (Small BAseline Subset) analysis using spaceborne SAR (Synthetic Aperture Radar) in order to detect a surface subsidence in Taebaek area, Kangwon, which are suitable to the monitoring of broad and inaccessible areas. During the period from October 2006 to June 2010, we acquired twenty-three ALOS PALSAR data sets (path/frame=425/730) for this study. The ninety-six differential interferograms with a perpendicular baseline less than 1100 m were constructed by ROI_PAC, then the mean velocity map of surface displacement was derived from SBAS analysis. As a result, it was confirmed that the ground displacement occurred about 4 cm/yr at Seokgong-Jangseong and Kyungdong mines and 2 cm/yr at Saehan-Eoryong-Jungdong and Hwangji mines in Taebaek area, Kangwon. It seems that the subsidence in study area is closely related to mining activities because the most of subsiding areas are well matched with mining areas. The subsidence at Kyungdong mine shows continuous and fast velocity in about $2{\times}2$ km area. Therefore the further analysis and the effort to prevent disaster are required in this area.

• Journal of the Society of Disaster Information
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• v.16 no.1
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• pp.60-69
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• 2020

Purpose: Cavity growth process monitoring is to periodically monitor changes in common size and topography for general and observational grades to predict the rate of common growth. The purpose of this study is to establish a systematic cavity management plan by evaluating the general and observational class community in a non-destructive method. Method: Using GPR exploration equipment, the acquired surface image and the surrounding status image are analyzed in the GPR probe radargram in depth, profile, and cross section of the location. The exact location is selected using the distance and surrounding markings shown on the road surface of the initial detection cavity, and the test cavity is analyzed by calling the radar at the corresponding location. Result: As a result of monitoring tests conducted at a cavity 30 sites of general and observation grade, nine sites have been recovered. Changes in scale were seen in 21 cavity locations, and changes in size and grade occurred in 13 locations. Conclusion: The under road cavity is caused by various causes such as damage to the burial site, poor construction, soil leakage caused by groundwater leakage, waste and ground vibration. Among them, indirect factors could infer the effects of groundwater and localized rainfall.

• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.287-302
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• 2005

Digital Elevation Models (DEMs) were generated by ERS-l/2 and JERS-1 SAR interferometry in Daejon area, Korea. The quality of the DEM's was evaluated by the Ground Control Points (GCPs) in city area where GCPs were determined by GPS surveys, while in the mountain area with no GCPs, a 1:25,000 digital map was used. In order to minimize errors due to the inaccurate satellite orbit information and the phase unwrapping procedure, a Differential InSAR (DInSAR) was implemented in addition to the traditional InSAR analysis for DEM generation. In addition, DEMs from GTOPO30, SRTM-3, and 1:25,000 digital map were used for assessment the resolution of the DEM generated from DInSAR. 5-6 meters of elevation errors were found in the flat area regardless of the usage and the resolution of DEM, as a result of InSAR analyzing with a pair of ERS tandem and 6 pairs of JERS-1 interferograms. In the mountain area, however, DInSAR with DEMs from SRTM-3 and the digital map was found to be very effective to reduce errors due to phase unwrapping procedure. Also errors due to low signal-to-noise ratio of radar images and atmospheric effect were attenuated in the DEMs generated from the stacking of 6 pairs of JERS-1. SAR interferometry with multiple pairs of SAR interferogram with low resolution DEM can be effectively used to enhance the resolution of DEM in terms of data processing time and cost.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1371-1388
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• 2023

Floods are becoming more severe and frequent due to global warming-induced climate change. Water disasters are rising in Korea due to severe rainfall and wet seasons. This makes preventive climate change measures and efficient water catastrophe responses crucial, and synthetic aperture radar satellite imagery can help. This research created 1,423 water body learning datasets for individual water body regions along the Han and Nakdong waterways to reflect domestic water body properties discovered by Sentinel-1 satellite radar imagery. We created a document with exact data annotation criteria for many situations. After the dataset was processed, U-Net, a deep learning model, analyzed water body detection results. The results from applying the learned model to water body locations not involved in the learning process were studied to validate soil water body monitoring on a national scale. The analysis showed that the created water body area detected water bodies accurately (F1-Score: 0.987, Intersection over Union [IoU]: 0.955). Other domestic water body regions not used for training and evaluation showed similar accuracy (F1-Score: 0.941, IoU: 0.89). Both outcomes showed that the computer accurately spotted water bodies in most areas, however tiny streams and gloomy areas had problems. This work should improve water resource change and disaster damage surveillance. Future studies will likely include more water body attribute datasets. Such databases could help manage and monitor water bodies nationwide and shed light on misclassified regions.

• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.237-245
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• 2007

GB-SAR (Ground-Based Synthetic Aperture Radar) system is an imaging radar that obtains high resolution 2-D image through a synthetic aperture effect from the accurate linear-motion control of antenna on the ground. The highly versatile system configurations and accurate repeatability of GB-SAR operation allow one to accurately monitor the stability of surface scatterers with millimeter accuracy by SAR interferometry. In this paper we introduce the development of a GB-SAR system and show the possibilities of SAR polarimetry and interferometry such as DInSAR, Cross-Track InSAR, Delta-f InSAR, and PSInSAR.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.239-239
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• 2018

위성 및 드론을 이용한 원격탐사 기술이 발전하고 다양한 산출물이 나타남에 따라 수자원 및 하천관리 분야에서 원격탐사기술 활용의 폭이 넓어지고 있다. 원격탐사 영상에서 획득할 수 있는 기본적인 가시영상 이외에도 적외영상, 초분광영상, 수위정보, 레이더 반사도 등을 활용하여 하천정보를 추정하려는 시도가 이루어져왔다. 본 연구에서는 원격탐사 영상에서 획득한 하폭을 기반으로 수리학적 하천유량산정을 기법을 적용하기 위해 등류 및 부등류 해석이 가능한 알고리즘과 프로그램을 개발하였다. 등류해석을 위해 GUI 기반 프로그램을 개발하였으며, 특정 하폭에서의 하천유량을 신속하게 계산할 수 있도록 단면 특성분석 모듈과 운동파 방정식 기반의 Manning 유속공식이 적용되도록 구성하였다. 또한, 부등류해석을 위해 스크립트기반의 프로그램을 개발하였다. 부등류 해석 프로그램에는 하천유량을 경계조건으로 수위를 계산하는 일반적인 부등류 수면곡선식의 해석절차를 하폭기반 원격하천 유량 산정 목적에 맞게 재구성하여 원격탐사기술로 획득한 하폭을 경계조건으로 하천 유량을 시산하는 알고리즘을 구현하였다. 본 프로그램을 활용하여 한국건설기술연구원 하천실험센터에서 드론을 이용한 등류/부등류 실험결과를 해석하였으며, 등류 흐름조건에서는 두 가지 해석방법 각각 14.3%, 14.7%의 유사한 평균상대오차를 나타내었고 부등류 흐름조건에서는 등류해석은 62.6%, 부등류해석은 15.8%의 평균상대오차를 나타내었다. 실규모하천에서의 원격하천유량 산정을 위해서는 등류기반 해석방법에 비해 비균일 하천단면에서의 부등류 현상을 모의할 수 있는 하폭기반 부등류 수면곡선의 시산 알고리즘이 유리한 것으로 판단된다.

• Korean Journal of Remote Sensing
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• v.18 no.4
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• pp.209-220
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• 2002

We carried out studies on SAR image intensity and interferometric phase over oyster sea farms. Strong backscattering was observed in amplitude images, and that was considered as a radar signal double bouncing from horizontal bars. These sea farming structures are not visible in satellite optical images except IKONOS image, so that it demonstrates the value of radar remote sensing as an effective tool in support of sea farm detection. The intensity of the image is sensitive to system parameters including wavelength, polarization, and look direction, but does not correlate to tide height. We found that the strongest backscattering can be obtained by L-band HH-polarization with a look direction perpendicular to the horizontal bar. We also succeeded in generating 21 coherent JERS-1 SAR interferometric pairs over the oyster farms. The general trend of the fringe rate of the interferometric phases appeared to be governed by altitude of ambiguity. The general trend was modeled by an inverse function and removed to have a residual phase. The residual phase showed a linear relation with the tide height. The results demonstrate for the first time that SAR can possibly be used to estimate sea level. However, the r.m.s. error of a regression line is 11.7 cm, and that is so far too large to make reliable assessments of sea level in practical applications. Further studies is required to improve the accuracy specifically using multi-polarization SAR data.