• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.286-292
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• 2006

Both composition and XOR are operations widely used to enhance security of cryptographic schemes. The more number of random permutations we compose (resp. XOR), the more secure random permutation (resp. random function) we get. Combining the two methods, we consider a generalized form of random function: $SUM^s - CMP^c = ({\pi}_{sc} ... {\pi}_{(s-1)c+1}){\oplus}...{\oplus}({\pi}_c...{\pi}_1)$ where ${\pi}_1...{\pi}_{sc}$ are random permutations. Given a fixed number of random permutations, there seems to be a trade-off between composition and XOR for security of $SUM^s - CMP^c$. We analyze this trade-off based on some upper bound of insecurity of $SUM^s - CMP^c$, and investigate what the optimal number of each operation is, in order to lower the upper bound.

• Review of KIISC
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• v.3 no.4
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• pp.63-70
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• 1993

본 논문에서는 n 개의 원소를 임의로 나열하는 대표적인 치환 발생 알고리즘을 소개하고 이들중 발생 치환의 랜덤성이 우수하다고 알려진 Knuth의 알고리즘을 근간으로 설계된 랜덤 치환 발생기의 암호학적 안전성을 분석하고 발생 치환들에 대한 난수 발생 수열 관점의 통계적 임의성과 연속 발생 치환끼리의 통계적 독립성 적용을 위한 통계량 소개 및 각 관점에서 통계적 검정을 통과함을 시뮬레이션 결과를 통하여 보인다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2493-2500
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• 1997

We propose a new key management scheme for multiuser group which is classified as hierarchical structure (sometimes it is called a multilevel security hierarchy) in the symmetric key cryptosystem. The proposed scheme is based on the trapdoor one-way permutations which are generated by the pseudo-random permutation algorithm, and it is avaliable for multilevel hierarchical structure composed of a totally ordered set and a partially ordered set, since it has advantage for time and storage from an implemental point of view. Moreover, we obtain a performance analysis by comparing with the other scheme, and show that the proposed scheme is very efficient for computing time of key generation and memory size of key storage.

• Journal of the Korean Data and Information Science Society
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• v.17 no.2
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• pp.449-453
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• 2006

In teaching statistics in the secondary school, most math teachers do it and students enjoy it well before 11th grade. But, both of teachers and students feel statistics hard at 11th grade, which has been contained permutations, combinations, random variables, probability distributions, hypotheses and tests for normal distribution. In this study, we explore the efficient teaching methods of statistics for math teachers and also find many students enjoying it.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.462-465
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• 2006

This paper is aimed at proposing the sampling method to reduce variance of statistical parameters in uncertainty analysis of concrete structures. The proposed method is a modification of Latin Hypercube sampling method. This uses specially modified tables of random permutations of rank number. Also, the Spearman coefficient is used to make modified tables. Numerical analysis is carried out to predict the uncertainty of axial shortening in prestressed concrete bridge. The numerical results show that the method is efficient for uncertainty analysis of complex structural system such as prestressed concrete bridges.

• 한국데이터정보과학회:학술대회논문집
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• 2006.04a
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• pp.229-233
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• 2006

In teaching statistics in the secondary school, most math teachers do it and students enjoy it well before 11th grade. But, both of teachers and students feel statistics hard at 11th grade, which has been contained permutations, combinations, random variables, probability distributions, hypotheses and tests for normal distribution. In this study, we explore the efficient teaching methods of statistics for math teachers and also find many students enjoying it.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.41-48
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• 2013

An efficient encryption algorithm based on the Data Encryption Standard (DES) for personal cloud computing environments is presented. The proposed algorithm improves data privacy, security and also encryption speed, compared with the triple DES. The improvement of the proposed algorithm stems from enhanced privacy inherent from the use of spread random interleaver in the place of the known substitution table for initial and final permutations in the DES algorithm. The simulation results demonstrate that the interleaver based DES (I-DES) is found to run faster than the triple DES algorithm and also offer improved security. The proposed algorithm also offers encryption for variable-length data using the Cipher Block Chaining (CBC).

• Journal of the Korea Computer Industry Society
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• v.2 no.2
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• pp.203-210
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• 2001

To estimate relational models and test the theoretical hypotheses of binary tree search algorithms, we built binary search trees with random permutations of n (number of nodes) distinct numbers, which ranged from three to seven. Probabilities for building binary search trees corresponding to each possible height and balance factor were estimated. Regression models with variables of number of nodes, height, and average number of comparisons were estimated and the theorem of O(1g(n)) was accepted experimentally by a Lack of Test procedure. Analysis of Variance model was applied to compare the average number of comparisons with three groups by height and balance factor of the trees to test theoretical hypotheses of a binary search tree performance statistically.

• International Journal of Concrete Structures and Materials
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• v.18 no.2E
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• pp.89-95
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• 2006

This paper proposes a modified method of Latin Hypercube sampling to reduce the variance of statistical parameters in uncertainty analysis of concrete structures. The proposed method is a modification of Latin Hypercube sampling method. This analysis method uses specifically modified tables of random permutations of ranked numbers. In addition, the Spearman coefficient is used to make modified tables. Numerical analysis is carried out to predict the uncertainty of axial shortening in prestressed concrete bridge. Statistical parameters obtained from modified Latin Hypercube sampling method and conventional Latin Hypercube sampling method are compared and evaluated by a numeric analysis. The results show that the proposed method results in a decrease in the variance of statistical parameters. This indicates the method is efficient and effective in the uncertainty analysis of complex structural system such as prestressed concrete bridges.

• The Korean Journal of Applied Statistics
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• v.23 no.6
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• pp.1209-1216
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• 2010

We describe shuffling process of 48 HwaTu(Flower) cards from a mathematical aspect and give the number of shuffles that are needed to arrive at a state of randomness. We observe that the cards are shuffled much less times in usual plays, that results in much riskier outcomes.