• Journal of Communications and Networks
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• v.17 no.6
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• pp.634-646
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• 2015

Assuming perfect channel state information (CSI) at the transmitter and receiver, the optimization problem of maximizing the minimum Euclidean distance between two received signals by a linear precoder is considered for multiple-input multiple-output (MIMO) systems with arbitrary dimensions and arbitraryary quadrature amplitude modulation (QAM) input. A general precoding framework is first presented based on the Gram matrix, which is shown for 2-dimensional (2-D) and 3-dimensional (3-D) MIMO systems when employing the ellipse expanding method (EEM). An extended precoder for high-dimensional MIMO system is proposed following the precoding framework, where the Gram matrix for high-dimensional precoding matrix can be generated through those chosen from 2-D and 3-D results in association with a permutation matrix. A complexity-reduced maximum likelihood detector is also obtained according to the special structure of the proposed precoder. The analytical and numerical results indicate that the proposed precoder outperforms the other precoding schemes in terms of both minimum distance and bit error rate (BER).

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.173-182
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• 2005

In this paper, we propose a landmark recognition method which is irrelevant to the camera viewpoint on the navigation for localization. Features in previous research is variable to camera viewpoint, therefore due to the wealth of information, extraction of visual landmarks for positioning is not an easy task. The proposed method in this paper, has the three following stages; first, extraction of features, second, learning and recognition, third, matching. In the feature extraction stage, we set the interest areas of the image. where we extract the corner points. And then, we extract features more accurate and resistant to noise through statistical analysis of a small eigenvalue. In learning and recognition stage, we form robust feature models by testing whether the feature model consisted of five corner points is an invariant feature irrelevant to viewpoint. In the matching stage, we reduce time complexity and find correspondence accurately by matching method using similarity evaluation function and Graham search method. In the experiments, we compare and analyse the proposed method with existing methods by using various indoor images to demonstrate the superiority of the proposed methods.

• Journal of KIISE:Software and Applications
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• v.30 no.10
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• pp.938-943
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• 2003

In this paper, we Propose a method using the Tikhonov-Miller process to improve the robustness of watermarking under various attacks. A visually recognizable pattern watermark is embedded in the LH2, HL2 and HH2 subband of wavelet transformed domain using threshold and besides watermark is embeded by utilizing HVS(Human Visual System) feature. The pattern watermark was interlaced after random Permutation for a security and an extraction rate. To demonstrate the improvement of robustness and similarity of the proposed method, we applied some basic algorithm of image processing such as scaling, filtering, cropping, histogram equalizing and lossy compression(JPEG, gif). As a result of experiment, the proposed method was able to embed robust watermark invisibility and extract with an excellent normalized correlation of watermark under various attacks.

• ETRI Journal
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• v.35 no.1
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• pp.131-141
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• 2013

Integral cryptanalysis, which is based on the existence of (higher-order) integral distinguishers, is a powerful cryptographic method that can be used to evaluate the security of modern block ciphers. In this paper, we focus on substitution-permutation network (SPN) ciphers and propose a criterion to characterize how an r-round integral distinguisher can be extended to an (r+1)-round higher-order integral distinguisher. This criterion, which builds a link between integrals and higher-order integrals of SPN ciphers, is in fact based on the theory of direct decomposition of a linear space defined by the linear mapping of the cipher. It can be directly utilized to unify the procedure for finding 4-round higher-order integral distinguishers of AES and ARIA and can be further extended to analyze higher-order integral distinguishers of various block cipher structures. We hope that the criterion presented in this paper will benefit the cryptanalysts and may thus lead to better cryptanalytic results.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.445-452
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• 2002

In this paper, we suggest the design of 128bit block cipher which is provable security based on mathematics theory. We have derived the 16$\times$16 matrix(i.e.,linear transformation) which is numerous active S-box, and we proved for DC and LC which prove method about security of SPN structure cipher algorithm. Also, the minimum number of active S-box, the maximum differential probabilities and the maximum linear probabilities in round function of 128bit block cipher algorithm which has an effect to DC and LC are derived.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.2
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• pp.190-202
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• 1995

The Optical Art is based on the principle of visual perception of the illusionary effects which induce psychological responses. It has influenced greatly on the Texile Design in that unique iJlusionary creativity of pattern simulates the visual sense of special movement; the dynamic psylosophy of vitalism. The Optical pattern has become a highly valued item due to its innovative effect in aesthetic direction. According to Vitor Vasarely the pioneer in this area, the integration and the inseparability of form and color which he calls 'Plastic Unity' provides the basis for the composition of infinite variety. The composition of infinite variety. The composition reveals the complex interaction between the space and form relating to order, repetition, combination and permutation. It is not simple to create optical patterns due to the extreme complexity composed by the multi-dimension and the infusion of form and color giving immensely varied movement. The purposes of this study are as follows; 1) to classify the complex processes of optical pattern on the basis of formative method. 2) to develop creative ideas for progressive contemporary textile design In this study, the analysis of applied methods is concentrated, which is based 1) on the gradual modification and on the transformation of the basic plastic elements which depend on thle direction of visual points involVing contradictory perspectives 2) on the composition varied special situations by repeating, overlapping and converging a series of idetUical units or by means of irrdiation, radiation and etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.333-337
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• 2006

Symmetric block ciper algorithm consists of a chains of operations such as permutation and substitution. There exists four kinds of operation mode, CBC, ECB, CFB, and OFB depending on the operation paradigm. Since the final ciper text is obtained through the many rounds of operations, it consumes much time. This paper proposes a pipelined design methodology which can improve the speed of crypto operations in ECB mode. Because the operations of the many rounds are concatenated in serial and executed concurrently, the overall computation time can be reduced significantly. The experimental result shows that the method can speed up the performance more than ten times.

• Journal for History of Mathematics
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• v.32 no.2
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• pp.61-77
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• 2019

The study was conducted based on the 'method of mathematical exploration through history'. In recent school education, 'Probability and Statistics' education has been emphasized, and as a result, the study has conducted a study on permutations. Permutation is used in a variety of fields, and in this study, we looked at the Derangement. The results of this study are as follows. First, analysis was made at current school mathematics level and academic mathematics level for Derangement. Second, the historical development process of derangement was examined. Third, based on this, the research direction of this study was decided to be 'Derangement number's triangle(Rencontres number's triangle)', and the inquiry for education expansion was carried out. Fourth, we have presented data on concrete educational expansion by discovering various mathematical facts of the Derangement number's triangle. We hope that the results of this study will provide meaningful implications for the application of mathematics and the presentation of new inquiry directions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.6098-6122
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• 2018

Cache-based side-channel attacks have achieved more attention along with the development of cloud computing technologies. However, current host-based mitigation methods either provide bad compatibility with current cloud infrastructure, or turn out too application-specific. Besides, they are defending blindly without any knowledge of on-going attacks. In this work, we present CacheSCDefender, a framework that provides a (Virtual Machine Monitor) VMM-based comprehensive defense framework against all levels of cache attacks. In designing CacheSCDefender, we make three key contributions: (1) an attack-aware framework combining our novel dynamic remapping and traditional cache cleansing, which provides a comprehensive defense against all three cases of cache attacks that we identify in this paper; (2) a new defense method called dynamic remapping which is a developed version of random permutation and is able to deal with two cases of cache attacks; (3) formalization and quantification of security improvement and performance overhead of our defense, which can be applicable to other defense methods. We show that CacheSCDefender is practical for deployment in normal virtualized environment, while providing favorable security guarantee for virtual machines.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.5
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• pp.3-14
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• 2002

Rijndael-like structure is the special case of SPN structure. The linear transformation of Rijndael-like structure consisits of linear transformations of two types, the one is byte permutation $\pi$ and the other is linear tranformation $\theta$＝ ($\theta_1, \theta_2, \theta_3, \theta_4$), where each of $\theta_i$ separately operates on each of the four rows of a state. The block cipher, Rijndael is an example of Rijndael-like structures. In this paper. we present a new method for upper bounding the maximum differential probability and the maximum linear hull probability for Rijndael-like structures.