• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.979-984
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• 2009

In this paper, the technique for production and encoding of new dot-type print watermark is proposed. The print watermark has characteristics similar to those of the digital watermark and function as link which change various first informations(texts, symbols, figures, etc) on the printed matter to secondary contents (sound, video, character, etc) corresponding each to informations on the printed matter. The proposed dot-type print watermark pattern is represented as $16{\times}16$ matrix in $0.4mm^2$ area and dots are printed on only 23 elements of $16{\times}16$ matrix. The size of each dot is so small(0.02mm)that it can not be seen. Because position of printed dots correspond to the position of each digit in binary notation in this paper, they are encoded easily and there are about 8,000,000 watermark patterns enough to express first information of printed matters. It was showed that the proposed print watermark patterns are recognized without difficulty by the own recognition device.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1479-1488
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• 2022

Accidents in which oil spills occur intermittently in the ocean due to ship collisions and sinkings. In order to prepare prompt countermeasures when such an accident occurs, it is necessary to accurately identify the current status of spilled oil. To this end, the Coast Guard patrols the target area with a fixed-wing airplane or helicopter and checks it with the naked eye or video, but it was difficult to determine the area contaminated by the spilled oil and its exact location on the map. Accordingly, this study develops a technology for direct ortho-rectification by automatically geo-referencing aerial images collected by the Coast Guard without individual ground reference points to identify the current status of spilled oil. First, meta information required for georeferencing is extracted from a visualized screen of sensor information such as video by optical character recognition (OCR). Based on the extracted information, the external orientation parameters of the image are determined. Images are individually orthorectified using the determined the external orientation parameters. The accuracy of individual orthoimages generated through this method was evaluated to be about tens of meters up to 100 m. The accuracy level was reasonably acceptable considering the inherent errors of the position and attitude sensors, the inaccuracies in the internal orientation parameters such as camera focal length, without using no ground control points. It is judged to be an appropriate level for identifying the current status of spilled oil contaminated areas in the sea. In the future, if real-time transmission of images captured during flight becomes possible, individual orthoimages can be generated in real time through the proposed individual orthorectification technology. Based on this, it can be effectively used to quickly identify the current status of spilled oil contamination and establish countermeasures.