• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2005년도 BIOINFO 2005
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• pp.228-233
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• 2005

The protein side-chain packing problem (SCPP) is known to be NP-complete. Various graph theoretic based side-chain packing algorithms have been proposed. However as the size of the protein becomes larger, the sampling space increases exponentially. Hence, one approach to cope with the time complexity is to decompose the graph of the protein into smaller subgraphs. Some existing approaches decompose the graph into biconnected components at an articulation point (resulting in an at-most 21-residue subgraph) or solve the SCPP by tree decomposition (4-, 5-residue subgraph). In this regard, we had also presented a deterministic based approach called as SPWCQ using the notion of maximum edge weight clique in which we reduce SCPP to a graph and then obtain the maximum edge-weight clique of the obtained graph. This algorithm performs well for a protein of less than 500 residues. However, it fails to produce a feasible solution for larger proteins because of the size of the search space. In this paper, we present a new heuristic approach for the side-chain packing problem based on the maximum edge-weight clique finding algorithm that enables us to compute the side-chain packing of much larger proteins. Our new approach can compute side-chain packing of a protein of 874 residues with an RMSD of 1.423${\AA}$.

• 대한수학회지
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• 제54권4호
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• pp.1121-1148
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• 2017

Go is an ancient game of great complexity and has a huge following in East Asia. It is also very rich mathematically, and can be played on any graph, although it is usually played on a square lattice. As with any game, one of the most fundamental problems is to determine the number of legal positions, or the probability that a random position is legal. A random Go position is generated using a model previously studied by the author, with each vertex being independently Black, White or Uncoloured with probabilities q, q, 1 - 2q respectively. In this paper we consider the probability of legality for two scenarios. Firstly, for an $N{\times}N$ square lattice graph, we show that, with $q=cN^{-{\alpha}}$ and c and ${\alpha}$ constant, as $N{\rightarrow}{\infty}$ the limiting probability of legality is 0, exp($-2c^5$), and 1 according as ${\alpha}$ < 2/5, ${\alpha}=2/5$ and ${\alpha}$ > 2/5 respectively. On the way, we investigate the behaviour of the number of captured chains (or chromons). Secondly, for a random graph on n vertices with edge probability p generated according to the classical $Gilbert-Erd{\ddot{o}}s-R{\acute{e}}nyi$ model ${\mathcal{G}}$(n; p), we classify the main situations according to their asymptotic almost sure legality or illegality. Our results draw on a variety of probabilistic and enumerative methods including linearity of expectation, second moment method, factorial moments, polyomino enumeration, giant components in random graphs, and typicality of random structures. We conclude with suggestions for further work.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.315-316
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• 2007

• 한국인터넷방송통신학회논문지
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• 제20권4호
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• pp.171-176
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• 2020

본 논문은 NP-난제로 널리 알려진 최대 가중치 독립집합(MWIS) 문제에 대해 다항시간으로 풀 수 있는 알고리즘을 제시하였다. MWIS 문제에 대해 지금까지는 특정 그래프 형태에 특화된 다항시간 알고리즘, 또는 분산형, 클러스터 형성 방법들이 제안되기도 하였으나 모든 그래프 형태에 적합한 단일화된 알고리즘이 제안되지 않고 있다. 따라서 본 논문에서는 어떠한 형태의 그래프에도 적합한 유일한 다항시간 알고리즘을 제안한다. 제안된 알고리즘은 최대 가중치를 갖는 정점 v_i를 v_i와 이웃하지 않은 정점 들 중 최대 가중치를 갖는 v_j 정점과 병합하였다. 제안된 알고리즘을 무방향 그래프와 트리에 적용한 결과, 최적 해를 얻었다. 특히, 일부 데이터에 대해서는 기존에 알려진 해를 개선하는 결과도 얻었다.

• 한국컴퓨터정보학회논문지
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• 제20권1호
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• pp.227-235
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• 2015

본 논문은 NP-완전으로 알려진 최대 클릭의 정확한 해를 선형시간으로 찾는 알고리즘을 제안하였다. 먼저, 주어진 그래프 G=(V,E)에서 최대 차수 ${\Delta}(G)$ 정점 $v_i$를 클릭의 대표 정점으로 결정한다. $v_i$ 인접 정점 $N_G(v_i)$에서 ${\Delta}(G)$ 정점 $v_j$를 선택하여 $N_G(v_i){\cap}N_G(v_j)$를 후보 클릭 w와 $v_k$로 결정한다. $d_G(v_k)$ 내림차순으로 $w=w{\cap}N_G(v_k)$를 얻는다. 마지막으로, $G{\backslash}w$그래프에서 동일한 절차를 수행하여 얻은 클릭이 기존에 얻은 클릭과 동일하거나 크면 이 클릭을 선정하는 검증과정을 거쳤다. 이와 같은 방법으로 독립된 다수의 클릭도 얻을 수 있는 장점이 있다. 제안된 알고리즘을 다양한 정규와 비정규 그래프에 적용한 결과 모든 그래프에 대해 선형시간 O(n)으로 정확한 해를 구하였다.

• 제어로봇시스템학회논문지
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• 제10권5호
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• pp.450-457
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• 2004

In this research, the automatic synthesis of knowledge models is proposed. which are the basis of the methods using qualitative models adapted widely in fault diagnosis and hazard evaluation of chemical processes. To provide an easy and fast way to construct accurate causal model of the target process, the Role-Behavior modeling method is developed to represent the knowledge of modularized process units. In this modeling method, Fault-Behavior model and Structure-Role model present the relationship of the internal behaviors and faults in the process units and the relationship between process units respectively. Through the multiple modeling techniques, the knowledge is separated into what is independent of process and dependent on process to provide the extensibility and portability in model building, and possibility in the automatic synthesis. By taking advantage of the Role-Behavior Model, an algorithm is proposed to synthesize the plant-wide causal model, Fault-Causality Graph (FCG) from specific Fault-Behavior models of the each unit process, which are derived from generic Fault-Behavior models and Structure-Role model. To validate the proposed modeling method and algorithm, a system for building FCG model is developed on G2, an expert system development tool. Case study such as CSTR with recycle using the developed system showed that the proposed method and algorithm were remarkably effective in synthesizing the causal knowledge models for diagnosis of chemical processes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.2015-2018
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• 2005

In this paper, we are willing to prepare the reasonable optimization, Combinatorial Optimization and Genetic Algorithm. Thus we define position status of end-effect (or terminative link module) using promised form, (G, M(G), A(G), and so on.). For this preparing step, the reorganizing procedure of Link and Joint Module is necessary, like as enumerating the kinematically identical assembly group of several links and joints. Thus, we draw a G, directed graph in a first step. Because, directed graph contains the path information between adjacent Link Module and Joint Module. From the directed graph,G, we can incite the Incidence Matrix, M(G). The incidence matrix, M(G), contains the contact information of the Link (Joint) Module and the type of Link (Joint). At the end of this paper, we generalize the modular information as a matrix form, A(G). From this matrix, we can make a population of assembly status. That is the finial output of this paper.

• 대한의용생체공학회:의공학회지
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• 제35권3호
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• pp.68-74
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• 2014

Recent research on mild cognitive impairment (MCI) has shown that cognitive and memory decline in this disease is accompanied by disruptive changes in the brain functional network. However, there have been no graph-theoretical studies using $^{11}C$-PIB PET data of the Alzheimer's Disease or mild cognitive impairment. In this study, we acquired $^{18}F$-FDG PET and $^{11}C$-PIB PET images of twenty-four normal aging control participants and thirty individuals with MCI from ADNI (Alzheimer's Disease Neuroimaging Initiative) database. Brain networks were constructed by thresholding binary correlation matrices using graph theoretical approaches. Both normal control and MCI group showed small-world property in $^{11}C$-PIB PET images as well as $^{18}F$-FDG PET images. $^{11}C$-PIB PET images showed significant difference between NC (normal control) and MCI over large range of sparsity values. This result will enable us to further analyze the brain using established graph-theoretical approaches for $^{11}C$-PIB PET images.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.386-403
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• 2016

The safety of nuclear power plants is analyzed by a probabilistic risk assessment, and the fault tree analysis is the most widely used method for a risk assessment with the event tree analysis. One of the well-known disadvantages of the fault tree is that drawing a fault tree for a complex system is a very cumbersome task. Thus, several graphical modeling methods have been proposed for the convenient and intuitive modeling of complex systems. In this paper, the reliability graph with general gates (RGGG) method, one of the intuitive graphical modeling methods based on Bayesian networks, is improved for the reliability analyses of dynamic systems that have various operation modes with time. A reliability matrix is proposed and it is explained how to utilize the reliability matrix in the RGGG for various cases of operation mode changes. The proposed RGGG with a reliability matrix provides a convenient and intuitive modeling of various operation modes of complex systems, and can also be utilized with dynamic nodes that analyze the failure sequences of subcomponents. The combinatorial use of a reliability matrix with dynamic nodes is illustrated through an application to a shutdown cooling system in a nuclear power plant.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.444-452
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• 2019

To assess the availability of a nuclear power plant's dynamic systems, it is necessary to consider the impact of dynamic interactions, such as components, software, and operating processes. However, there is currently no simple, easy-to-use tool for assessing the availability of these dynamic systems. The existing method, such as Markov chains, derives an accurate solution but has difficulty in modeling the system. When using conventional fault trees, the reliability of a system with dynamic characteristics cannot be evaluated accurately because the fault trees consider reliability of a specific operating configuration of the system. The dynamic reliability graph with general gates (DRGGG) allows an intuitive modeling similar to the actual system configuration, which can reduce the human errors that can occur during modeling of the target system. However, because the current DRGGG is able to evaluate the dynamic system in terms of only reliability without repair, a new evaluation method that can calculate the availability of the dynamic system with repair is proposed through this study. The proposed method extends the DRGGG by adding the repair condition to the dynamic gates. As a result of comparing the proposed method with Markov chains regarding a simple verification model, it is confirmed that the quantified value converges to the solution.