• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.6
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• pp.131-142
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• 2007

In this paper, semi-fragile watermarking algorithm was proposed for the application to RP(Rapid Prototyping) system. In the case of the perceptual change or distortion of the original one, the prototype product will be affected from the process because the RP system requires the high precision measure. Therefore, the geometrical transformations like translation, rotation and scaling, the mesh order change and the file format change are used in the RP system because they do not change the basic shapes of the 3D models, but, the decimation and the smoothing are not used because they change the models. The proposed algorithm which is called semi-fragile watermarking is robust against to these kinds of manipulations which preserve the original shapes because it considers the limitations of the RP system, but fragile against to the other manipulations which change the original shapes. This algorithm does not change the model shapes after embedding the watermark information, that is, there is no shape difference between the original model and the watermarked model. so, it will be useful to authenticate the data integrity and hide the information in the field of mechanical engineering which requires the high precision measure.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.523-532
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• 2007

This study utilized the 1/25,000 topographic map of the upper area from the Geum-ho watermark located at the middle of Geum-ho river from the National Geographic Information Institute. For the analysis, first, the influence of the size of critical area to the hydro topographic factors was examined changing grid size to $10m{\times}10m,\;30m{\times}30m\;and\;50m{\times}50m$, and the critical area for the formation of a river to $0.01km^2{\sim}0.50km^2$. It is known from the examination result of watershed morphology according to the grid size that the smaller grid size, the better resolution and accuracy. And it is found, from the analysis result of the degree of the river according to the minimum critical area for each grid size, that the grid size does not affect on the degree of the river, and the number of rivers with 2nd and higher degree does not show remarkable difference while there is big difference in the number of 1st degree rivers. From the results above, it is thought that the critical area of $0.15km^2{\sim}0.20km^2$ is appropriate for formation of a river being irrelevant to the grid size in extraction of hydro topographic parameters that are used in the runoff analysis model using topographic maps. Therefore, the GIUH model applied analysis results by use of the river level difference law proposed in this study for the explanation on the outflow response-changing characters according to the decision of a critical value of a minimum level difference river, showed that, since an ogival occurrence time and an ogival flow volume are very significant in a flood occurrence in case of not undertow facilities, the researcher could obtain a good result for the forecast of river outflow when considering a convenient application of the model and an easy acquisition of data, so it's judged that this model is proper as an algorism for the decision of a critical value of a river basin.