• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.3
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• pp.395-404
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• 2013

A pattern matching algorithm plays an important role in traffic identification and classification based on predefined patterns for intrusion detection and prevention. As attacks become prevalent and complex, current patterns are written using regular expressions, called regexes, which are expressed into the deterministic finite automata(DFA) due to the guaranteed worst-case performance in pattern matching process. Currently, because of the increased complexity of regex patterns and their large number, memory-efficient DFA from states reduction have become the mainstay of pattern matching process. However, most of the previous works have focused on reducing only the number of states on a single automaton, and thus there still exists a state blowup problem under the large number of patterns. To solve the above problem, we propose a new state compression algorithm that merges states on multiple automata. We show that by merging states with the same input character on multiple automata, the proposed algorithm can lead to a significant reduction of the number of states in the original DFA by as much as 40.0% on average.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.273-276
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• 2000

본 논문에서는 문서처리와 비디오 스트림 처리에 이용되는 이론적 배경을 고찰하고 , 제시된 이론을 바탕으로 하나의 비디오 스트림을 결정적 유한 오토마타 형태의 논리적인 구조로 재구성하여 사용자의 요구나 수준에 따라 가변적인 재생 시간을 갖는 비디오 브라우징 시스템을 구현하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.209-212
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• 2001

본 논문의 연구 목적은 효율적인 비디오 브라우징에 관한 연구이다. 비디오 스트림을 효율적으로 저장 및 재생하는 브라우징 시스템의 기본 구조로는 결정적 유한 오토마타를 사용하였다. 인덱싱 단계에서는 기존의 비디오 정보 또는 오디오 정보 한가지만을 사용하여 분야별로 특수하게 모델링하는 방법을 개선하여 비디오 스트림과 오디오 스트림 모두를 이용하는 새로운 인덱싱 방법을 제시하였다. 즉, 일차적으로 비디오 정보를 이용하여 동영상 데이터를 장면 단위로 분할한 후, 오디오 정보를 이용하여 에피소드 단위로 분할하여 인덱싱을 실행하였다. 이를 결정적 유한 오토마타 형태의 논리적인 구조로 에피소드들을 재구성하여 사용자의 요구에 따라 가변적인 재생 시간을 갖는 비디오 브라우징 시스템을 설계하였다.

• Journal of KIISE:Software and Applications
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• v.37 no.9
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• pp.712-721
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• 2010

This paper proposes a new fire-flame detection method using probabilistic membership function of visual features and Fuzzy Finite Automata (FFA). First, moving regions are detected by analyzing the background subtraction and candidate flame regions then identified by applying flame color models. Since flame regions generally have continuous and an irregular pattern continuously, membership functions of variance of intensity, wavelet energy and motion orientation are generated and applied to FFA. Since FFA combines the capabilities of automata with fuzzy logic, it not only provides a systemic approach to handle uncertainty in computational systems, but also can handle continuous spaces. The proposed algorithm is successfully applied to various fire videos and shows a better detection performance when compared with other methods.

• Journal of Korea Multimedia Society
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• v.8 no.11
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• pp.1556-1564
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• 2005

Various optimization techniques are deployed in the compilation process of a source program for improving the program's execution speed and reducing the size of the source code. Of the optimization pattern matching techniques, the string pattern matching technique involves finding an optimal pattern that corresponds to the intermediate code. However, it is deemed inefficient due to excessive time required for optimized pattern search. The tree matching pattern technique can result in many redundant comparisons for pattern determination, and there is also the disadvantage of high cost involved in constructing a code tree. The objective of this paper is to propose a table-driven code optimizer using the DFA(Deterministic Finite Automata) optimization table to overcome the shortcomings of existing optimization techniques. Unlike other techniques, this is an efficient method of implementing an optimizer that is constructed with the deterministic automata, which determines the final pattern, refuting the pattern selection cost and expediting the pattern search process.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.478-480
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• 2011

우리는 패턴매칭에서 많이 사용되는 정규언어의 연산 ${\sum}^*L$에 대한 일반적인 경우의 상태복잡도와 단항 알파벳인 경우의 상태복잡도를 살펴본다. 정규언어의 상태복잡도는 해당 정규언어를 승인하는 최소결정적 유한 인식기의 상태 개수를 말한다. 패턴매칭, 검색엔진에 많이 사용되는 어떤 정규언어 L 에 대한 연산 ${\sum}^*L$의 상태복잡도를 살펴봄으로써, 좀 더 효율적인 리소스 관리를 통해 좀 더 빠른 검색을 할 수 있다.

• The KIPS Transactions:PartA
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• v.14A no.1 s.105
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• pp.31-38
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• 2007

Code Optimization is converting to a code that is equivalent to given program but more efficient, and this process is processed in Code Optimizer. This paper designed and processed Code Optimizer Generator that automatically generates Code Optimizer. In other words Code Optimizer is automatically generated for DFA Pattern Matching which finds the optimal code for the incoming pattern description. DFA Pattern Matching removes redundancy comparisons that occur when patterns are sought for through normalization process and improves simplification and structure of pattern shapes for low cost. Automatic generation of Code Optimization for DFA Pattern Matching eliminates extra effort to generate Code Optimizer every time the code undergoes various transformations, and enables formalism of Code Optimization. Also, the advantage of making DFA for optimization is that it is faster and saves cost of Code Optimizer Generator.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.819-826
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• 2018

The generalized Hamming weight is one of the important parameters of the linear code. It determines the performance of the code when the linear codes are applied to a cryptographic system. In addition, when the block code is decoded by soft decision using the lattice diagram, it becomes a measure for evaluating the state complexity required for the implementation. In particular, a bit-parallel multiplier on finite fields based on trinomials have been studied. Cellular automata(CA) has superior randomness over LFSR due to its ability to update its state simultaneously by local interaction. In this paper, we deal with the efficient synthesis of the pseudo random number generator, which is one of the important factors in the design of effective cryptosystem. We analyze the property of the characteristic polynomial of the simple 90/150 transition rule block, and propose a synthesis algorithm of the reversible 90/150 CA corresponding to the trinomials $x^2^n+x^{2^n-1}+1$($n{\geq}2$) and the 90/150 reversible CA(RCA) corresponding to the maximum weight polynomial with $2^n$ degree by using this rule block.