• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.511-514
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• 2006

비정상행위 탐지를 위한 프로파일 기술은 침임탐지시스템의 성능 향상을 위한 핵심기술로서, 높은 공격 탐지율과 침입탐지시스템의 수행 시간 단축을 위해 반드시 요구되는 기술이다. 최근 인터넷의 보급과 활성화로 웹 어플리케이션 보안을 위한 연구가 활발히 진행되고 있으나, 웹 애플리케이션의 개발 언어와 공격 특성을 반영하지 못해 그 효율성이 저하되고 있다. 본 논문에서는 웹 공격 탐지를 위해 연구 되었던 서열정렬 알고리즘을 이용한 웹 공격 탐지의 성능 개선을 위하여 웹 애플리케이션 개발에 주로 사용되는 스크립트파일을 기반으로 한 프로파일 방법을 제안하고 실험 결과를 기술하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.496-498
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• 2003

접미사 배열은 긴 문자열에 대해 효율적인 문자열 검색을 가능하게 하는 자료구조이다. 접미사 배열은 문자열의 접미사들의 사전식 정렬순서를 배열로 저장한다. 비슷한 효과를 가진 접미사 트리에 비해서 접미사 배열은 저장 공간을 적게 차지하기 때문에 생명정보과학의 염기 서열 등 큰 크기의 문자열의 처리에 더욱 유리하다. 본 논문에서는 2003년에 발표된 Ko-Aluru, K$\square$rkk$\square$inen-Sanders 및 기존의 Manber-Myers 등 세 개의 접미사 배열 생성 알고리즘들의 염기 서열 입력 자료에 대한 실행 시간 및 기억 장치 사용량을 실험을 통해 비교한다. 특히 Ko-Aluru와 K$\square$rkk$\square$inen-Sanders 알고리즘은 실행 시간 및 저장 공간의 이론적인 복잡도가 O(n)으로 동일하기 때문에 실험을 통해서 계산 복잡도에 숨어있는 상수를 비교한다. 실험 결과 K$\square$rkk$\square$inen-Sanders 알고리즘이 가장 효율적임을 보인다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.13-15
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• 2002

생물정보학 관련 프로그램들은 대부분 인터넷을 통해서 많은 생물학자, 생화학자 들에게 생물 정보 검색 및 처리 서비스를 제공한다. 이런 서비스를 제공하는 많은 프로그램들은 데이터베이스로부터 유전자 등의 데이터를 검색하고 처리한다. 이때 각각 클라이언트의 요청마다 매번 데이터베이스의 검색을 수행한다면 많은 시간이 걸리게 된다. 또한 서버에 과부하를 초래하여 응답시간이 길어질 수 있다. 본 논문에서는 서버의 과부하와 응답시간을 줄이기 위해 사용자의 요청을 그룹화하여 일정 시간 간격으로 일괄 처리하는 방법을 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.14 no.1
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• pp.73-80
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• 2009

G protein-coupled receptors(GPCRs) family is a cell membrane protein, and plays an important role in a signaling mechanism which transmits external signals through cell membranes into cells. But, GPCRs each are known to have various complex control mechanisms and very unique signaling mechanisms. Structural features, and family and subfamily of GPCRs are well known by function. and accordingly, the most fundamental work in studies identifying the previous GPCRs is to classify the GPCRs with given protein sequences. Studies for classifying previously identified GPCRs more easily with mathematical models have been mainly going on. In this paper Considering that functions of proteins are determined by their stereoscopic structures, the present paper proposes a method to compare secondary structures of two GPCRs having different amino acid sequences, and then detect an unknown GPCRs assumed to have a same function in databases of previously identified GPCRs.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.586-589
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• 2012

표절과 관련된 이슈가 주목받고 있는 상황에서 표절을 검출하는 방법에 대한 연구가 활발히 진행되고 있다. 일반적으로 표절구간 검출을 위해 복잡한 자연어처리와 같은 의미론적 접근방법이 아닌 비교적 단순한 어휘기반의 문자열 처리 방법을 사용한다. 대표적인 방법으로는 지문법 (Fingerprinting)과 서열정렬 (Sequence alignment) 등이 있다. 하지만 이 방법들을 이용하여 대용량 문서에 대한 표절검사를 수행하기에는 시공간적 복잡도의 문제가 발생한다. 본 논문에서는 이러한 단점을 극복하기 위해 NGS (Next Generation Sequencing)에서 사용하는 BWT (Burrows-Wheeler Transform)[1]를 이용한 탐색방법을 응용한다. 또한 부분표절구간을 검출하고 정확도를 향상시키기 위해 질의문서를 분할하여 작은 조각으로 만든 뒤, 조각들에 대한 질의탐색을 수행한다. 본 논문에서는 질의문서를 분할하는 두 가지 방법을 소개한다. 두 가지 방법은 k-mer analysis를 이용한 방법과 random-split analysis를 이용한 방법으로, 각 방법의 장단점을 실험을 통해 분석하고 실제 부분표절구간의 검출 정확도를 측정하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.6
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• pp.354-367
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• 2010

There are many methods for analyzing patterns in time series data. Although stock data represents a time series, there are few studies on stock pattern analysis and prediction. Since people believe that stock price changes randomly we cannot predict stock prices using a scientific method. In this paper, we measured the degree of the randomness of stock prices using Kolmogorov complexity, and we showed that there is a strong correlation between the degree and the accuracy of stock price prediction using our semi-global alignment method. We transformed the stock price data to quantized string sequences. Then we measured randomness of stock prices using Kolmogorov complexity of the string sequences. We use KOSPI 690 stock data during 28 years for our experiments and to evaluate our methodology. When a high Kolmogorov complexity, the stock price cannot be predicted, when a low complexity, the stock price can be predicted, but the prediction ratio of stock price changes of interest to investors, is 12% prediction ratio for short-term predictions and a 54% prediction ratio for long-term predictions.

• Bioinformatics and Biosystems
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• v.1 no.2
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• pp.99-102
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• 2006

The Basic Local Alignment Search Tool (BLAST) is one of the most established software in bioinformatics research and it compares a query sequence against the libraries of known sequences in order to investigate sequence similarity. Expressed Sequence Tags (ESTs) are single-pass sequence reads from mRNA (or cDNA) and represent the expression for a given cDNA library and the snapshot of genes expressed in a given tissue and/or at a given developmental stage. Therefore, ESTs can be very valuable information for functional genomics and bioinformatics researches. Although major bio database (DB) websites including NCBI are providing BLAST services and EST data, local DB and search system is demanding for better performance and security issue. Here we present animal EST DBs and local BLAST search system. The animal ESTs DB in NCBI Genbank were divided by animal species using the Perl script we developed. and we also built the new extended DB search systems fur the new data (Local Animal BLAST Search System: http://bioinfo.kohost.net), which was constructed on the high-capacity PC Cluster system fur the best performance. The new local DB contains 650,046 sequences for Bos taurus(cattle), 368,120 sequences for Sus scrofa (pig), 693,005 sequences for Gallus gallus (fowl), respectively.

• Korean Journal of Plant Resources
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• v.19 no.5
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• pp.628-633
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• 2006

ITS DNA sequences from five individuals, representative of five groups designated according to the degree of leaf teeth and lobes from simple to palmate compound leaf in the Viola albida complex, established and further analysed in order to solve the taxonomic difficulty. A total 702 bp was sequenced at the 5.8S ribosomal DNA and internal transcribed spacer 1 and 2. The 5.8S coding region is 163 bp, and has no sequence variations. The ITS1 and ITS2 noncoding regions have a little bit sequence variations, and those were further analysed by the methods of the analysis of variance (ANOVA), the analysis of sequence divergence and the phylogenetic analysis. The result of ANOVA showed no significant differences among individuals investigated. The analysis of sequence divergence with Kimura 2-parameter distance revealed that in-groups showed much less than 0.05 in absolute value among individuals, while two out groups more than 0.05, V. grypoceras and V. orientalis. This result appeared that the sequence divergence among in-groups was not yet occurred in the species level but situated at somewhere below the species level. In the phylogenetic analysis, two outgroups formed the basal clades in order. Five individuals in-groups formed a clade. The clade was, however, not very robust as around 50% in bootstrap value, suggesting that this result was not meaningful in the phylogenetic point of views.

• Korean Journal of Plant Resources
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• v.24 no.4
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• pp.358-369
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• 2011

The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA from genus Chrysosplenium were sequenced to address phylogenetic relationship. ITS including 5.8S sequence varied in length from 647 bp to 653 bp. Among them, 219 sites were variable sites with parsimony-informative. The aligned sequences were analyzed by maximum parsimony (MP) and neighbor-joining (NJ) methods. In the strict consensus trees of parsimony analysis, the monophyly of Chrysosplenium was supported by 100% bootstrap value. The first clade, C. pseudofauriei was at the basal position of the genus, and others formed two clades with high bootstrap support. The second clade included Ser. Pilosa and Ser. Oppositifolia and third clade included Ser. Alternifolia and Ser. Flagellifera. The NJ trees showed essentially the same topology. Finally, DNA sequences of ITS regions were useful phylogenetic marker in this genus. Based on the ITS and ridge seed morphological results, C. sphaerospermum Maxim. and C. valdepilosum (Ohwi) S.H. Kang & J.W. Han were discussed their scientific names and taxonomic positions.

• Applied Biological Chemistry
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• v.44 no.3
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• pp.153-161
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• 2001

In order to isolate genes involved in ecdysteroids biosynthesis in plants, total RNA was isolated from Achyranthes japonica Nakai, and RT-PCR was performed using degenerate primers selected based on the results of multi-alignment of four cytochrome P450 genes from plants and a putative ecdysone 20-hydroxylase gene from an insect. Fourteen partial cDNA clones showing unique base sequences were obtained, out of which six showed homologies at the levels of nucleotide and amino acid sequences to the other cytochrome P450 genes known to be involved in the ecdysteroid biosynthesis. Of the six clones, four showed relatively high homologies to a putative ecdysone 20-hydroxylase gene isolated from an insect.