• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.616-624
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• 2003

The exhaustion of our water resource due to the leakage of waterworks renders it urgent to detect water leakage effectively. In the paper, the detection of water leakage makes use of a pound-penetrating radar(GPR). The region of water leakage is implemented by an acryl box filled with methanol, and then the scale-down experiments are performed by using the GPR system developed in our laboratory. The validity of GPR experiments is assured by showing that the measured data agree well with those finite-difference time-domain(FDTD) simulated results in the same situation. The feasibility of GPR system for the detection of water leakage is investigated by displaying B-scan images according to the distribution of water leakage.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.151-154
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• 2013

We typically have a variety of equipment that can detect and track targets, and detect and track target quickly and accurately through the exchange of the information between each piece of equipment. These equipments have similar detection area(FOV), but some are different due to the limits of the resolution of the equipments. In this paper, we studied the method of reducing time to search and detect target, and also did the method of tracking automatically it.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.788-791
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• 2010

One Source Multi-Use(원 소스 멀티 유스)'란 하나의 소재를 서로 다른 장르에 적용해 파급효과를 노리는 마케팅 전략을 말한다. 이 같은 '원 소스 멀티 유스'의 대표적인 소재가 바로 만화다. 그러나 근래에 들어서는 만화를 비롯하여 소설, 게임, 애니메이션, 영화 등을 원천소스로 하여 다양한 장르로 변형되고 있다. 그중 대표적인 것이 '공포의 외인구단'과 '바람의 나라'를 들 수 있다. '공포의 외인구단'은 이현세의 원작이고(1982-1983)이고 '바람의 나라'는 김진의 만화가 원전이다(1992-2008현재). '공포의 외인구단은 곧바로 영화화 됐으며 20년 후인 2009년에 드라마로 만들어 졌다. '바람의 나라는' 1997년 국내 최초의 온라인게임으로 만들어져 현재까지 많은 사랑을 받으며 서비스되는 게임이며 또한 2006년과 2007년에는 뮤지컬로도 만들어졌고 최근에는 TV드라마로 만들어져 많은 인기를 얻고 있다. 또 다른 예로는 '툼레이더'를 들 수 있는데 이는 게임이 원작이고 게임의 인기를 업고 영화로 만들어졌으며 세계적인 흥행성공에 힘입어 속편까지 제작된 상태이다. 이에 본 연구에서는 '원 소스 멀티 유스'의 대표적인 성공사례인 '바람의 나라'와 '툼 레이더'의 여러 요소 중 시각적인 요소인 캐릭터와 영상이미지의 분석을 통해 흥행요인을 도출하고자 한다.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.2
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• pp.147-157
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• 2018

There are increasing demands to provide early warning against intruding drones and cope with potential threats. Commercial anti-drone systems are mostly based on simple target detection by radar reflections. In real scenario, however, it becomes essential to obtain drone radar signatures so that hostile targets are recognized in advance. We present experimental test results that micro-Doppler radar signature delivers partial information on multi-rotor platforms and exhibits limited performance in drone recognition and classification. Afterward, we attempt to generate high resolution profile of flying drone targets. To this purpose, wide bands radar signals are employed to carry out inverse synthetic aperture radar(ISAR) imaging against moving drones. Following theoretical analysis, experimental field tests are carried out to acquire real target signals. Our preliminary tests demonstrate that high resolution ISAR imaging provides effective measures to detect and classify multiple drone targets in air.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.28.1-28.1
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• 2009

고해상도 카메라 혹은 영상레이더 안테나를 장착하여 지구를 관측하는 인공위성의 구조체는 발사하중 및 우주환경의 궤도 상에서 탑재된 장비를 보호하게끔 설계되고 제작된다. 구조체는 발사체와의 공진을 피할 수 있는 강성을 가져야 하며, 주 구조물의 강도는 발사체로부터의 하중을 견딜 수 있도록 설계된다. 또한, 극한 우주환경 하에서 구조체의 변형이 최소화 되도록 설계된다. 상기 설계 내용이 완벽하게 구조체에 반영되기 위해서는 우주용자재 및 공정의 적절한 선정이 이루어 져야 한다. 이 논문은 인공위성 구조체에 사용된 Metal, Non-metal 및 조립용 Hardware 자재 (규격 포함)와 측면패널/플랫폼 및 태양전지판 Substrate 등 주요 구조물의 제작공정에 대하여 기술한다. 그리고, 국산화가 이루어진 조립용 Hardware의 Dry Film Lubricant 공정에 대해서도 기술한다.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.17-24
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• 2018

Polar fomat algorithm (PFA) was derived from medical imaging theory, known as back projection, to process synthetic aperture radar(SAR) data. The difference between the operating condition of SAR and back projection assumption makes two distortions. First, the focusing performance of PFA is degraded in proportion to distances from the scene center. Second, the geometric accuracy in SAR images is distorted. Several methods were introduced to mitigate the distortions, but some disadvantages, such as the geometric discontinuity, are arisen when sub-images are combined. This paper proposes the novel method to compensate the geometric distortion with chirp Z-transform (CZT). This method corrects precisely the geometric errors without any problems, because a whole image can be processed all at once.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.192.1-192.1
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• 2012

영상레이더 (SAR: Synthetic Aperture Radar) 혹은 통신 안테나/탑재체를 장착한 위성은 원하는 주파수 대역의 운용을 위해 대형 안테나 구조물 장착이 필수적이다. 이러한 대형 구조물은 일체형으로 제작되어 위성체에 접속되었을 때, 요구 무게 및 점유하는 부피가 매우 큰 특징을 지닌다. 따라서, 대형 안테나 구조물의 중량으로 인해 발사비 증가가 불가피하며, 페어링 내부의 허용된 공간에 안테나 크기는 큰 제약적 요인이 된다. 그리고, 전개식이어도, 전개후 질량 관성이 큰 구조물이 된다. 위성체의 발사 비용과 직결되는 안테나의 경량화를 위한 많은 기술이 연구되고 있다. 특히, 접이식 팽창형 안테나는 반사체의 유연한 메쉬 구조 및 경량 지지구조물로 안테나의 무게를 줄이고 수납 효율을 향상시킨다. 또한, 전개 후 안테나의 목적한 기능을 충분히 보장함과 동시에 질량 관성이 작은 구조물에 의한 위성의 기동성을 극대화할 수 있다. 국내에서도 전천후 지상관측감시 및 통신 안테나의 필요성 증대에 따라 초경량 전개형 안테나 개발의 필요성이 크게 대두되고 있으나, 현재까지는 관련 기술개발 사례가 전무한 실정으로 국내 독자적 기술 확보가 시급한 실정이다.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.447-460
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• 2022

It is well known that satellite synthetic aperture radar interferometry (InSAR) has been widely used for the observation of surface displacement owing to earthquakes, volcanoes, and subsidence very precisely. In wetlands where vegetation exists on the surface of the water, it is possible to create a water level change map with high spatial resolution over a wide area using the InSAR technique. Currently, a number of imaging radar satellites are in operation, and most of them support a ScanSAR mode observation to gather information over a large area at once. The Cienaga Grande de Santa Marta (CGSM) wetland, located in northern Colombia, is a vast wetland developed along the Caribbean coast. The CGSM wetlands face serious environmental threats from human activities such as reclamation for agricultural uses and residential purposes as well as natural causes such as sea level rise owing to climate change. Various restoration and protection plans have been conducted to conserve these invaluable environments in recognition of the ecological importance of the CGSM wetlands. Monitoring of water level changes in wetland is very important resources to understand the hydrologic characteristics and the in-situ water level gauge stations are usually utilized to measure the water level. Although it can provide very good temporal resolution of water level information, it is limited to fully understand flow pattern owing to its very coarse spatial resolution. In this study, we evaluate the L-band ALOS-2 PALSAR-2 ScanSAR mode to observe the water level change over the wide wetland area using the radar interferometric technique. In order to assess the quality of the interferometric product in the aspect of spatial resolution and coherence, we also utilized ALOS-2 PALSAR-2 stripmap high-resolution mode observations.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.164-170
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• 2012

This paper presents that the comparison results of AT (Active Transponder) positions obtained from different measurements: the result of GPS device and evaluated position from the SAR (Synthetic Aperture Radar) image, and active transponders can be useful as GCPs(Ground Control Points) in SAR images. The X-band AT are installed on the wide-and-flat area to improve SCR(signal-to-clutter ration), and activated to represent impulse response function in order to operate as one point target in SAR images. Cosmo-SkyMed operating at X-band frequency are used to provide SAR images of AT. The comparison of AT position is performed by using the result of GPS device field measurement and AT SAR images. ENVI-SARscape S/W is used to evaluate AT position in the SAR images. From the comparison, it is shown that AT are useful as GCPs for SAR images.

• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1239-1249
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• 2018

Optical remote sensing sensors provide visually more familiar images than radar images. However, it is difficult to discriminate sea ice types in optical images using spectral information based machine learning algorithms. This study addresses two topics. First, we propose a semantic segmentation which is a part of the state-of-the-art deep learning algorithms to identify ice types by learning hierarchical and spatial features of sea ice. Second, we propose a new approach by combining of semi-supervised and active learning to obtain accurate and meaningful labels from unlabeled or unseen images to improve the performance of supervised classification for multiple images. Therefore, we successfully added new labels from unlabeled data to automatically update the semantic segmentation model. This should be noted that an operational system to generate ice type products from optical remote sensing data may be possible in the near future.