• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.729-731
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• 2016

The efficiency of genetic algorithm may be improved, as genetic generation increases. However, a number of algorithms are needed until desired results are obtained. In addition, if Hoc unit increases when linked to a network, there may be a need to compare with all the cases, which would result in many algorithms at a time, and if a single process deals with such algorithms, the efficiency will decrease. Therefore, efficiency of overall network will be decreased in the end. Proposal algorithm in this thesis introduced cells, units of router group, for distributed processing of previous genetic algorithm. This thesis presented ways to reduce search delay time of overall network through cell-based genetic algorithm.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.813-820
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• 2005

To develop a genetic algorithm about job shop scheduling with alternative routing, we are performed that genetic algorithm efficiency analysis of job shop scheduling with alternative routing, First, we proposed genetic algorithm for job shop scheduling with alternative routing. Second, we applied genetic algorithm to traditional benchmak problem appraise a compatibility of genetic algorithm. Third, we compared with dispatching rule and genetic algorithm result for problem Park[3].

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2037-2043
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• 2015

Proposed algorithm in this thesis introduced cells, units of router group, to conduct distributed processing of previous genetic algorithm. This thesis presented ways to reduce search delay time of overall network through cell-based genetic algorithm. Also, through this experiment, in case of a network was damaged in existing optimal path algorithm, Dijkstra algorithm, the proposed algorithm was designed to route an alternative path and also as it has a 2nd shortest path in cells of the damaged network so it is faster than Dijkstra algorithm, The study showed that the proposal algorithm can support routing of alternative path, if Dijkstra algorithm is damaged in a network.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.03a
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• pp.65-69
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• 1998

차량주행안내 시스템에서 경로 안내 기능은 사용자에게 출발지와 목적지간의 최단의 경로를 찾아 주는 역할을 수행한다. 그런데 최단경로를 찾는 문제도 중요하지만, 다음과 같이 최단 경로 이외에 대체경로가 필요한 경우가 자주 발생한다. 첫째, 목적지나 출발지가 유사한 차량에 대해서 복수개의 경로를 제시함으로써, 교통량을 분산시킬수 있어, 전체 도로망의 효율을 높일 수 있다. 둘째, 운전자의 선호도가 각기 다르기 때문에 이를 만족시키기 위해서는 복수개의 경로 제시가 필요하다. 본 연구에서는 대체경로의 적합성을 평가할수 있는 지표와 유전 알고리즘 기반의 효율적인 대체경로를 탐색 기법을 제시한다.

• Communications for Statistical Applications and Methods
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• v.16 no.6
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• pp.925-936
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• 2009

There very many approaches to impute missing values in the iid. case. However, it is hardly found the imputation techniques in the Markov random field(MRF) case. In this paper, we show that the imputation under MRF is just to impute by fitting the normal mixture model(NMM) under several practical assumptions. Our multivariate normal mixture model based approaches under MRF is applied to impute the missing pixel values of 3-variate (R, G, B) color image, providing a technique to smooth the imputed values.

• Journal of KIISE:Databases
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• v.29 no.2
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• pp.148-157
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• 2002

Caching in meta-search engines can improve the response time of users' request. We describe the cache scheme in our meta-search engine in terms of its architecture and operational flow. In particular, we propose a popularity-driven cache algorithm that utilizes popularities of queries to determine cached data to be purged. The popularity is a value that represents the normalized occurrence frequency of user queries. This paper presents how to collect popular queries and how to calculate query popularities. An empirical performance evaluation of the popularity-driven caching with the traditional schemes (i.e., least recently used (LRU) and least frequently used (LFU)) has been carried out on a collection of real data. In almost all cases, the proposed replacement policy outperforms LRU and LFU.

• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.305-315
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• 2010

In this paper, a frequentistic approach to impute the values of R, G, B-components in random missing pixels of color image is provided. Under assumption that the given image is a realization of Gaussian Markov random field, its model is designed such that each neighbor pixel values for a given pixel follows (independently) the normal distribution with covariance matrix scaled by an evaluates of the similarity between two pixel values, so that the imputation is not to be affected by the neighbors with different color. An approximate EM-based algorithm maximizing the underlying likelihood is implemented to estimate the parameters and to impute the missing pixel values. Some experiments are presented to show its effectiveness through performance comparison with a popular interpolation method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.399-410
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• 2002

Web cache, which is functionally another word of proxy server, is located between client and server. Web cache has a limited storage area although it has broad bandwidth between client and proxy server, which are usually connected through LAN. Because of limited storage capacity, existing objects in web cache can be deleted for new objects by some rules called replacement algorithm. Hit rate and byte-hit rate are general metrics to evaluate replacement algorithms. Most of the replacement algorithms do satisfy only one metric, or sometimes none of them. In this paper, we propose two replacement algorithms to achieve both high hit rate and byte-hit rate with great satisfaction. In the first algorithm, the cache is appropriately partitioned according to file types as a basic model. In the second algorithm, the cache is composed of two levels; the upper level cache is managed by the basic algorithm, but the lower level is collectively used for all types of files as a shared area. To show the performance of the proposed algorithms, we evaluate hit rate and byte-hit rate of the proposed replacement algorithms using the trace driven simulation.

• Review of KIISC
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• v.32 no.6
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• pp.53-63
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• 2022

양자컴퓨팅 시대가 도래하면 현재까지 안전하다고 여겨지는 암호 알고리즘이 쉽게 해독될 수 있다. 이에 대비하기 위해 NIST에서는 PQC 알고리즘 개발 프로젝트를, 한국에서는 KpqC 프로젝트를 통해 양자컴퓨팅 대응 암호 알고리즘을 개발하고 있다. 양자컴퓨팅 시대에 안전한 새로운 암호 알고리즘 개발도 중요하지만, 암호취약점 발견이 일상이 될 경우 시스템 변경을 최소화하면서 기존 암호 알고리즘을 신규 암호 알고리즘으로 대체할 수 있는 암호화 선제대응력(Crypto Agility)에 대한 준비도 필요하다. 본 논문에서는 기존 시스템의 영향을 최소화하면서 암호 관련 요소들(암호 알고리즘, 암호 파라미터, 암호 프로토콜 등)을 대체하기 위해 필수적인 암호화 선제대응력 요구사항을 제안하고, 이를 실행하기 위해 정책기관에서 추진되어야 할 실행항목을 제시한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.629-634
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• 2001

보안프로토콜로 기존의 SSL에서 인증 기능을 각각의 사용자, 상점, 금융기관에 강화시킨 ECSCET 프로토콜이 있다. ECSET프로토콜의 구성성분으로 비밀키 알고리즘의 DES, 공개키 알고리즘의 RSA, 메시지 서명 알고리즘인 SHA중 공개키 알고리즘의 RSA, 메시지 서명 알고리즘인 SHA중 공개키 알고리즘의 RSA를 ECC로 대체함으로 암, 복호화 속도를 분석하였고, 서명 알고리즘으로 타원곡선을 이용한 ECDSA을 보였다.