• 충청수학회지
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• 제23권4호
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• pp.885-892
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• 2010

In this paper we study the structures and properties of a single cycle T-finction, whose theory has been lately proposed by Klimov and Shamir. Any cryptographic system based on T-functions may be insecure. Some of the TSC-series stream ciphers have been successfully attacked by some attacks. So it is important to analyze every aspect of a single cycle T-function. We study some properties on a single cycle T-function and we show some examples are single cycle T-functions by these properties, whose proof is easier than existing methods.

• 충청수학회지
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• 제28권2호
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• pp.331-343
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• 2015

Invertible transformations over n-bit words are essential ingredients in many cryptographic constructions. When n is large such invertible transformations are usually represented as a composition of simpler operations such as linear functions, S-P networks, Feistel structures and T-functions. Among them we study T-functions which are probably invertible transformations and are very useful in stream ciphers. In this paper we study the number of single cycle T-functions satisfying some conditions and characterize single cycle T-functions on $(\mathbb{Z}_2)^n$ generated by some elements in $(\mathbb{Z}_2)^{n-1}$.

• 충청수학회지
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• 제24권4호
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• pp.927-934
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• 2011

Invertible transformations over n-bit words are essential ingredients in many cryptographic constructions. When n is large (e.g., n = 64) such invertible transformations are usually represented as a composition of simpler operations such as linear functions, S-P networks, Feistel structures and T-functions. Among them we study T-functions which are probably invertible and are very useful in stream ciphers. In this paper we study some conditions on a T-function h(x) such that f(x) = x + h(x) has a single cycle on ${\mathbb{Z}}_{2^n}$.

• 충청수학회지
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• 제21권2호
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• pp.259-268
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• 2008

To the design of secret key, there are two types of basic approaches called the tame approach and the wild approach. In the tame approach we try to use only simple primitives such as linear feedback shift registers and to prove mathematical theorems about their cryptographic properties. In the wild approach we try to use crazy compositions of operations which mix a variety of domains in a nonlinear and nonalgebraic way. There are several papers which try to bridge this gap by considering semi-wild constructions. A T-function on n-bit words plays an important role in semi-wild constructions. In this paper we study the invertibility and the period of some T-functions. Especially we characterize some polynomials which has a single cycle property.

• 충청수학회지
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• 제22권4호
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• pp.789-797
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• 2009

Invertible transformations over n-bit words are essential ingredients in many cryptographic constructions. When n is large (e.g., n = 64) such invertible transformations are usually represented as a composition of simpler operations such as linear functions, S-P networks, Feistel structures and T-functions. Among them we will study T-functions which are probably invertible transformation and are very useful in stream ciphers. In this paper we will show that $f(x)=x+(g(x)^2{\vee}C)$ mod $2^n$ is a permutation with a single cycle of length $2^n$ if both the least significant bit and the third significant bit in the constant C are 1, where g(x) is a T-function.

• 충청수학회지
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• 제29권4호
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• pp.573-584
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• 2016

Invertible transformations over n-bit words are essential ingredients in many cryptographic constructions. Such invertible transformations are usually represented as a composition of simpler operations such as linear functions, S-P networks, Feistel structures and T-functions. Among them T-functions are probably invertible transformations and are very useful in stream ciphers. In this paper we will characterize a secure trinomial on ${\mathbb{Z}}_{2^n}$ which generates an n-bit word sequence without consecutive elements of period $2^n$.

• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.247-255
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• 2011

Invertible functions with a single cycle property have many cryptographic applications. The main context in which we study them in this paper is pseudo random generation and stream ciphers. In some cryptographic applications we need a generator which generates binary sequences of period long enough. A common way to increase the size of the state and extend the period of a generator is to run in parallel and combine the outputs of several generators with different period. In this paper we will characterize a secure quadratic polynomial on $\mathbb{Z}_{2^n}$, which generates a binary sequence of period long enough and without consecutive elements.

• 지역연구
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• 제34권1호
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• pp.49-60
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• 2018

본 연구의 목적은 청년 1인 가구 증가와 함께 나타나는 주거 문제의 원인을 분석하는 것이다. 본 연구에서는 생애 주기 가설을 기반으로 주택 수요 함수를 추정하였다. 추정 결과, 청년 1인 가구의 주택 수요와 항상소득 잔차로 인한 주택 수요가 다른 집단에 비해 유의미하게 낮게 나타났다. 이는 청년 1인 가구의 주택 소비에 항상소득이 충분히 실현되지 못하고 있으며, 이를 뒷받침할 금융 시장의 역할이 미비함을 의미한다. 본 연구에서는 항상소득 실현의 어려움과 주택 금융 부족을 청년 1인 가구 주택 수요 불균형 현상의 원인으로 분석하였다. 따라서 청년 1인 가구의 주택 문제를 해결하기 위해 항상소득과 현재 주택 수요의 균형을 유도하는 정책이 도입되어야 한다.

• Computers and Concrete
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• 제21권3호
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• pp.291-298
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• 2018

In this study, the flexural fatigue performance of concrete beams made with 100% Coarse Recycled Concrete Aggregates (RCA) and 100% Coarse Natural Aggregates (NA) were statistically commanded. For this purpose, the experimental fatigue test results of earlier researcher were investigated using two parameter Weibull distribution. The shape and scale parameters of Weibull distribution function was evaluated using seven numerical methods namely, Graphical method (GM), Least-Squares (LS) regression of Y on X, Least-Squares (LS) regression of X on Y, Empherical Method of Lysen (EML), Mean Standard Deviation Method (MSDM), Energy Pattern Factor Method (EPFM) and Method of Moments (MOM). The average of Weibull parameters was used to incorporate survival probability into stress (S)-fatigue life (N) relationships. Based on the Weibull theory, as single and double logarithm fatigue equations for RCA and NA under different survival probability were provided. The results revealed that, by considering 0.9 level survival probability, the theoretical stress level corresponding to a fatigue failure number equal to one million cycle, decreases by 8.77% (calculated using single-logarithm fatigue equation) and 6.62% (calculated using double logarithm fatigue equation) in RCA when compared to NA concrete.

• 한국인터넷방송통신학회논문지
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• 제21권1호
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• pp.61-68
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• 2021

과거의 레이다는 임무 특성에 맞게 사격통제레이다, 탐지레이다, 추적레이다, 영상획득 레이다 등으로 구분되어 운영해왔다. 하지만 다기능 레이다는 표적 탐지, 추적, 피아식별, 재머 탐지 및 대응 등 단일 시스템 안에서 다양한 임무를 수행한다. 때문에 한정된 자원으로 다기능 레이다를 운용하기 위한 효율적인 자원관리는 필수적이다. 특히 탐지된 표적의 추적을 위한 표적 위협도와 이를 바탕으로 추적주기를 선정하는 방법은 중요한 이슈다. 위협표적을 집중으로 추적하다보면 다른 영역에서 탐지된 표적을 효율적으로 관리할 수 없고 탐지에 집중을 하면 추적성능이 저하될 수 있다. 때문에 효과적인 스케줄링이 필수적이다. 본 논문에서는 다기능 레이다 스케줄링 방안인 TaP(Time and Priority)알고리즘과 이를 구성하기 위한 소프트웨어적 설계 방법에 대해 제안한다.