• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.3 s.309
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• pp.68-75
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• 2006

In this paper, we propose an adaptive video watermarking method using human visual system(HVS) and characteristics of three-dimensional cosine transform (3D-DCT) cubes. We classify 3D-DCT cubes into three patterns according to the distribution of coefficients in the 3D-DCT cube: cube with motion and textures, cube with high textures and little motion, and cube with little textures and line motion. Images are also classified into three types according to the ratio of these patterns: images with motion and textures, images with high textures and little motion, and images with little textures and little motion. The proposed watermarking method adaptivelyinserts the watermark on the coefficients of the mid-range in the 3D-DCT cube using the appropriately learned sensitivity table and the proportional constants depending on the patterns of 3D-DCT cubes and types of images. Experimental results show that the proposed method achieves better performance in terms of invisibility and robustness than the previous method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.417-425
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• 2003

H.264, which is the latest video coding standard of both ITU-T(International Telecommunication Union-Telecommunication standardization sector) and MPEG(Moving Picture Experts Group), adopts new video coding tools such as variable block size motion estimation, multiple reference frames, quarter-pel motion estimation/compensation(ME/MC), 4${\times}$4 Integer DCT(Discrete Cosine Transform), and Rate-Distortion Optimization, etc. These new video coding tools provide good coding of efficiency compared with existing video coding standards as H.263, MPEG-4, etc. However, these new coding tools require the increase of encoder complexity. Therefore, in order to apply H.264 to many real applications, fast algorithms are required for H.264 coding tools. In this paper, when encoder MacroBlock(MB) mode is decided by rate-distortion optimization tool, fast mode decision algorithm by skipping variable block size ME/MC and spatial-predictive coding, which occupies most encoder complexity, is proposed. In terms of computational complexity, the proposed method runs about 4 times as far as JM(Joint Model) 42 encoder of H.264, while the PSNR(peak signal-to-noise ratio)s of the decoded images are maintained.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.101-112
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• 1999

In this paper, the codebook design method of VQ (vector quantization) is proposed an method to extract feature data of image for multimedia information searching. Conventional VQ codebook design methods are unsuitable to extract the feature data of images because they have too much computation time, memory for vector decoding and blocking effects like DCT (discrete cosine transform). The proposed design method is consists of the feature extraction by WT (wavelet transform) and the data group divide method by PCA (principal component analysis). WT is introduced to remove the blocking effect of an image with high compressing ratio. Computer simulations show that the proposed method has the better performance in processing speed than the VQ design method using SOM (self-organizing map).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1790-1802
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• 1997

A wavelet transform coding method that fulfills the requirements of HD-VCR(high definition video casstte recorder) for studio applications in proposed. A constant bit rate is achieved by a forward rate control technique whcih determins the quantizer stepsize based on the coding results fo the previous frame. We also propose a two-level coder that consists of both the IDC(independently decodable code) and the DDC(dependently decodable code). To minimize error propagation, the transformed coefficients are restructured into transform blocks which are represented by a tree structure. The result shows thta the proposed coding scheme produces better picture quality with block effects than that of DCT(discrete cosine transform) based coding schemes at the same compression ratio. The proposed method meets most of the requirements of HD-VCR.

• Korean Journal of Legislative Studies
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• v.24 no.1
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• pp.241-276
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• 2018

This article measures equal weighted voting to evaluate the fairness of a redistricting system operated in the $4^{th}$ to the $6^{th}$ metropolitan council elections using a new index. The cosine square index using in the article would be useful on what we see the ratio of the equality of population among metropolitan regions and the fairness of the whole electoral system, along with its simple calculation. The results of the fairness of the $4^{th}$ to the $6^{th}$ metropolitan council elections calculated by the cosine square index are as follow: Because the $4^{th}$ metropolitan council election uniformly elects two members for each electoral district regardless of the size of the population, it has a low equality of population between districts. But as a result of the decision of the Constitutional Court in 2007, standard of population variation in electoral district has been strengthened to 4 : 1 from the $5^{th}$ metropolitan council election. It increases significantly equality of population between districts from the $5^{th}$ metropolitan council election. But in the elections from the $4^{th}$ to the $6^{th}$ metropolitan council elections, Rural electoral districts continuously show the lowest equality of population between districts. It also shows the growing disparity between urban and rural areas as well as between capital and non-capital. This paper emphasizes that electoral apportionment in local council elections should reflect regional diversity and community identity.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.544-557
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• 2010

This paper addresses the problem of controlling the envelope's power peak of single carrier modulated signals, band limited by root-raised cosine (RRC) pulse shaping filters, in order to reduce power amplifier back-off for very small aperture terminals ground stations. Magnitude modulation (MM) is presented as a very efficient solution to the peak-to-average power ratio problem. This paper gives a detailed description of the MM concept and its recent evolutions. It starts by extending the look-up-table (LUT) based approach of the MM concept to M-ary constellations with M ${\leq}$ 16. The constellation and RRC symmetries are explored, allowing considerable reduction on LUT computation complexity and storage requirements. An effective multistage polyphase (MPMM) approach for the MM concept is then proposed. As opposed to traditional LUT-MM solutions, MM coefficients are computed in real-time by a low complexity multirate filter system. The back-off from high-power amplifier saturation is almost eliminated (reduction is greater than 95%) with just a 2-stage MPMM system even for very demanding roll-off cases (e.g., ${\alpha}$ = 0,1). Also, the MPMM is independent of modulation in use, allowing its easy application to constellations with M > 16.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.1
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• pp.43-53
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• 2001

WT(Wavelet Transform) is used to avoid blocking effect that is the disadvantage of JPEG using DCT(Discrete Cosine Transform). Because the proposed coding scheme is the same as JPEG, the proposed algorithm is compatible with that of JPEG. To achieve the goal, WT'ed image is reconstructed into 8$\times$8 coding block. Each coding block is quantized with the proposed weighting matrix that is derived from human visual characteristic and error analysis in WT'ed domain. By experiments, the proposed algorithm is superior to JPEG, in terms of PSNR(Peak Signal to Noise Ratio) and WMSE(Weighted Mean Square Error).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1214-1221
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• 2005

In this paper, we propose a digital watermarking method for still images, in which the human visual system (HVS) is used in the discrete cosine transform (DCT) domain. The modulation transfer function (MTF) of the HVS model is employed to increase the invisibility of the inserted watermark in images. The proposed watermarking method is shown to be robust to several common image processing techniques, including lowpass filtering and cropping. Also, using the energy relationship of the DCT, we derive the equation that directly computes the watermark weighting factor in the DCT domain for the specified peak signal to noise ratio (PSNR) of the still image and the length of watermark to be inserted. The difference between desired PSNR and PSNR in spatial domain is within 0.07dB for the 7 test images.

• International Journal of Computer Science & Network Security
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• v.22 no.1
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• pp.139-148
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• 2022

Research into wireless sensor networks (WSNs) is a trendy issue with a wide range of applications. With hundreds to thousands of nodes, most wireless sensor networks interact with each other through radio waves. Limited computational power, storage, battery, and transmission bandwidth are some of the obstacles in designing WSNs. Clustering and routing procedures have been proposed to address these concerns. The wireless sensor network's most complex and vital duty is routing. With the Greedy Perimeter Stateless Routing method (GPSR), an efficient and responsive routing protocol is built. In packet forwarding, the nodes' locations are taken into account while making choices. In order to send a message, the GPSR always takes the shortest route between the source and destination nodes. Weighted directed graphs may be constructed utilising four distinct distance metrics, such as Euclidean, city block, cosine, and correlation distances, in this study. NS-2 has been used for a thorough simulation. Additionally, the GPSR's performance with various distance metrics is evaluated and verified. When compared to alternative distance measures, the proposed GPSR with correlation distance performs better in terms of packet delivery ratio, throughput, routing overhead and average stability time of the cluster head.

• Advances in nano research
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• v.12 no.2
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• pp.117-137
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• 2022

Effect of thickness stretching on free vibration, bending and buckling behavior of carbon nanotubes reinforced composite (CNTRC) laminated nanoplates rested on new variable elastic foundation is investigated in this paper using a developed four-unknown quasi-3D higher-order shear deformation theory (HSDT). The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Two new forms of CNTs reinforcement distribution are proposed and analyzed based on cosine functions. By considering the higher-order nonlocal strain gradient theory, microstructure and length scale influences are included. Variational method is developed to derive the governing equation and Galerkin method is employed to derive an analytical solution of governing equilibrium equations. Two-dimensional variable Winkler elastic foundation is suggested in this study for the first time. A parametric study is executed to determine the impact of the reinforcement patterns, nonlocal parameter, length scale parameter, side-t-thickness ratio and aspect ratio, elastic foundation and various boundary conditions on bending, buckling and free vibration responses of the CNTRC plate.