• Journal of Korea Multimedia Society
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• v.5 no.5
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• pp.552-561
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• 2002

In this paper, a new watermarking algorithm for STL files which contains 3D geometric information as triangular facets is proposed. STL files are widely used in rapid prototyping industry as a standard interchange format. The proposed algorithm inserts multi-bit watermark information into the surface normal vector and vertex description area of STL file without distorting the original 3D geometric information. According to the watermark bits, the position of normal vector and the direction of vertex sequence are modulated. The proposed algorithm is robust to the attack of changing the order of the triangular meshes. In addition, the invisibility requirement is also satisfied. Experiment results show that the proposed algorithm can encode and decode watermark bits into the various STL files without any distortion of 3D shape.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.177-180
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• 2002

In this paper, an effective digital watermarking method for copyright protection of binary image data is proposed. First, a binary image is grouped into feature regions which have geometrical features and general one. The watermark for authentication is embedded in general regions in order to preserve geometrical features regions. We have used run-length code and special runs for grouping feature regions and general one. For invisibility of watermark, we have embedded the watermark considering transition sensitivity of each pixel in general regions. The proposed method is applied to some binary image such as character, signature, seal, and fingerprint image to evaluate performance. By the experimental results, the proposed method preserve feature regions of original image and have higher invisibility of watermarks.

• Journal of the Korea Society of Computer and Information
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• v.8 no.3
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• pp.61-65
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• 2003

In this paper, a novel watermarking technique that based on wavelet packet transform using PIM is proposed for the copyright of the digital images. We divide wavelet packet coefficients into detailed blocks and calculate the complexity of each block using PIM. Because human is impervious to the change in the complex area, the embedding watermark to the selected coefficients using PIM enhances invisibility. From the experimental results, the proposed algorithm shows better invisibility and robustness performance in a general signal processing such as JPEG and SPIHT lossy compression, median filtering. Especially, it demonstrates better performance for the low bit-rate compression in the images that include many high frequency components.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11C
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• pp.1592-1599
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• 2004

In this paper, we proposed the 3D mesh watermarking using projection onto convex sets (POCS). 3D mesh is projected iteratively onto two constraint convex sets until it satisfy the convergence condition. These sets consist of the robustness set and the invisibility set that designed to embed watermark Watermark is extracted without original mesh by using the decision values and the index that watermark is embedded. Experimental results verified that the watermarked mesh have the robustness against mesh simplification, cropping, affine transformation, and vertex randomization as well as the invisibility.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.149-158
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• 2005

This paper proposed a blind watermarking method for video contents which satisfies both the invisibility and the robustness to attacks to prohibit counterfeiting, modification, illegal usage and illegal re-production of video contents. This watermarking algorithm targets MPEG compression system and was designed to control the amount of watermarking to be inserted according to the adaptive quantization scale code to follow the adaptive quantization of the compression system. The inserting positions of the watermark were chosen by considering the frequency property of an image and horizontal, vertical and diagonal property of a $8{\times}8$ image block. Also the amount of watermarking for each watermark bit was decided by considering the quantization step. This algorithm was implemented by C++ and experimented for invisibility and robustness with MPEG-2 system. The experiment results showed that the method satisfied enough the invisibility of the inserted watermark and robustness against attacks. For the general attacks, the error rate of the extracted watermark was less than $10\%$, which is enough in robustness against the attacks. Therefore, this algorithm is expected to be used effectively as a part in many MPEG systems for real-time watermarking, especially in the sensitive applications to the network environments.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.701-704
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• 2000

In this paper, we focus on digital watermarking for color images. At first, in order to embed the watermark signal in color image, we converted RGB color space to YCbCr color space which is a world-wide digital component video standard. In addition, we adopted the acceptable degree of color difference in order to keep the invisibility.

• Proceedings of the KSPS conference
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• 1996.10a
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• pp.482-487
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• 1996

Korean fortis consonant is not included in the consonantal inventory, but a result of phonetic implementation at the phonetic level, P. With the framework of Cognitive Phonology, a construction of Post Obstruent Tensification is proposed in such a way that rule-ordering is eliminated. This enables us to overcome methodological problems raised in former analyses of fortis under geminate hypothesis, and give a uniform account for three categories of fortis consonants. By assuming extrasyllabicity of verb-stem-final, consonant neutralization of fortis in the coda position is explained by the invisibility at the P-level. and, therefore. modification of Coda Neutralization rule is called for.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.381-381
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• 2012

Noise control in underwater environments is an entirely different beast from its airborne counterpart, partly because of the orders-of-magnitude difference in density and compressibility between water and air. One of the most popular systems ever used for (passive) noise reduction under water is an anechoic coating known as "alberich," which was developed by the German during the Second World War and are still used today in naval applications. This talk looks back on some recent developments in underwater noise control, ranging from acoustic metamaterials to active noise control techniques, specifically geared to achieving underwater invisibility.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.267-270
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• 2002

In this paper, a new watermarking method using an iterative scheme is proposed. The proposed method consists of two parts: watermark generation and its insertion. In the watermark generation, random signals with normalized distribution N(0,1) are produced and modified using an iterative scheme. In the watermark insertion, the resulting watermark signals are inserted into selected transform coefficients with various scaling parameters in order to achieve the invisibility and robustness against illegal attacks. The simulation results show that the proposed method has good performance for various attacks including image compression, filtering, etc.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.1092-1095
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• 2000

Computer graphics(CG) is one of the most useful tools by which we can easily understand visible/invisible natural phenomena. Namely, phenomena in the universe is attractive one because of its beauty and invisibility on the earth. For gravitational tensing phenomena, a ray tracing algorithm is proposed based on a lens-plane. In the method, position of gravitational sources is restricted. In this paper an improved visualization method is proposed, which can represent more complex situation than the previous method.