• 대한기계학회논문집A
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• 제20권11호
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• pp.3507-3515
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• 1996

This paper presents an attempt to find the physical structure of dynamic systems which achieves the behavior of a given system function. The scheme pursued by the paper would be regarded as synthesizing dynamic systems, and a method to synthesize them analytically is proposed by means of bond graph prototypes. The method adopts several conceptsused to synthesize networks in the electrical field, but yet deconstrates its own strengths such as the freedom from assigning causality and determining junction types. Also, itis shown that this method has further advantages in reticulating a given specification into feedforward and feedback components relative to network synthesis and the method is examined though an example to trace the outline of the analytical synthesis of dynamic systems using bond graph prototypes.

• KIEAE Journal
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• 제11권6호
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• pp.95-100
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• 2011

Although Space Syntax is a well-known technique for spatial analysis, debates have taken place among some researchers because the Space Syntax discards geometric information as both shapes and sizes of spaces, and hence may cause some inconsistencies. Therefore, this study aims at developing methods to recognize and manage spatial shapes for more precise space syntax analysis. To reach this goal, this study employed both a graph theory and binary spatial partitioning (BSP) tree to recognize and manage spatial information. As a result, spatial shapes and sizes could be recognized by checking loops in graph converted from spatial shapes of built environment. Each spatial shape could be managed sequentially by BSP tree with hierarchical structure. Through such recognition and management processes, convex maps composed of the fattest and fewest convex spaces could be drawn. In conclusion, we hope that the methods developed here will be useful for urban planning to find appropriate purposes of spaces to satisfy the sustainability of built environment on the basis of the spatial and social relationships in urban spaces.

• 한국경영과학회지
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• 제39권2호
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• pp.131-140
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• 2014

Customer networks go through constant changes. They may expand or shrink once they are formed. In dynamic environments, it is a critical corporate challenge to identify and manage influential customer groups in a cost effective way. In this context, we apply inverse optimization theory to suggest an efficient method to manage customer networks. In this paper, we assume that there exists a subset of nodes that might have a large effect on the network and that the network can be modified via some strategic actions. Rather than making efforts to find influential nodes whenever the network changes, we focus on a subset of selective nodes and perturb as little as possible the interaction between nodes in order to make the selected nodes influential in the given network. We define the following problem based on the inverse optimization. Given a graph and a prescribed node subset, the objective is to modify the structure of the given graph so that the fixed subset of nodes becomes a minimum dominating set in the modified graph and the cost for modification is minimum under a fixed norm. We call this problem the inverse dominating set problem and investigate its computational complexity.

• 전기학회논문지
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• 제56권11호
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• pp.2051-2057
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• 2007

In Oriental medicine, the status of a tongue is the important indicator to diagnose one's health like physiological and clinicopathological changes of inner parts of the body. The method of tongue diagnosis is not only convenient but also non-invasive and widely used in Oriental medicine. However, tongue diagnosis is affected by examination circumstances a lot like a light source, patient's posture and doctor's condition. To develop an automatic tongue diagnosis system for an objective and standardized diagnosis, segmenting a tongue is inevitable but difficult since the colors of a tongue, lips and skin in a mouth are similar. The proposed method includes preprocessing, graph-based over-segmentation, detecting positions with a local minimum over shading, detecting edge with color difference and estimating edge geometry from the probable structure of a tongue, where preprocessing performs down-sampling to reduce computation time, histogram equalization and edge enhancement. A tongue was segmented from a face image with a tongue from a digital tongue diagnosis system by the proposed method. According to three oriental medical doctors' evaluation, it produced the segmented region to include effective information and exclude a non-tongue region. It can be used to make an objective and standardized diagnosis.

• 한국정보과학회논문지:데이타베이스
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• 제32권6호
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• pp.585-592
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• 2005

시맨틱 웹은 차세대 웹으로 연구되고 있으며 시맨틱 웹 상에서는 사람이 아닌 컴퓨터가 이해할 수 있는 정보를 처리해야 한다. 이러한 웹 자원의 내용을 기술하기 위해 온톨로지(Ontology)들을 이용한다. 이러한 온톨로지 중에 현재 W3C에서 제안한 OWL이 부각되고 있다. OWL을 처리하는 데이타 베이스에서 데이타는 그래프 형태로 저장되어 그래프 탐색을 통해 질의 처리를 수행한다. 본 논문에서는 OWL 데이타를 효율적으로 처리하기 위하여 시그니처를 이용한 최적화 기법을 제안한다. 논문에서 제안한 최적화 기법은 질의 수행 시 각 노드의 탐색 회수를 줄여 질의 수행을 빠르게 할 수 있게 한다.

• Journal of Information Processing Systems
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• 제13권5호
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• pp.1158-1167
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• 2017

Many real-world applications information are organized and represented with graph structure which is often used for representing various ubiquitous networks, such as World Wide Web, social networks, and protein-protein interactive networks. In particular, similarity evaluation between graphs is a challenging issue in many fields such as graph searching, pattern discovery, neuroscience, chemical compounds exploration and so forth. There exist some algorithms which are based on vertices or edges properties, are proposed for addressing this issue. However, these algorithms do not take both vertices and edges similarities into account. Towards this end, this paper pioneers a novel approach for similarity evaluation between graphs based on formal concept analysis. The feature of this approach is able to characterize the relationships between nodes and further reveal the similarity between graphs. Therefore, the highlight of our approach is to take vertices and edges into account simultaneously. The proposed algorithm is evaluated using a case study for validating the effectiveness of the proposed approach on detecting and measuring the similarity between graphs.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2008년도 추계학술발표대회
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• pp.275-278
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• 2008

데이터마이닝은 현재 매우 각광 받고 있는 분야다. 연관규칙탐사는 트랜잭션 데이터베이스에서 일정빈도 이상의 패턴을 찾아내는 작업을 말한다. 그중 빈발서브그래프패턴 마이닝은 최근 관심이 늘어나고 있으며, 그 활용도 또한 매우 높다. 그래프마이닝은 아이템셋마이닝보다 훨씬 더 많은 계산을 필요로 한다. 중복을 최소화 하는 방법이 필요하며, 그중 가장 좋은 성능을 보이는 GASTON 알고리즘을 분석한다.

• 한국콘텐츠학회논문지
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• 제17권12호
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• pp.1-10
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• 2017

오픈 데이터는 전세계적으로 많은 관심을 받고 있다. 우리나라 정부는 데이터 개방에 많은 노력을 기울이고 있다. 그러나, 공공 데이터의 양적 증가에도 불구하고 데이터에 대한 부족함이 여전히 지적되고 있다. 본 논문은 공공 데이터를 의미적으로 연결해 데이터 공유 및 활용을 향상시키기 위한 방법을 제안한다. 첫째, 대한민국 행정구역의 정의와 행정구역 사이의 관계를 의미적으로 표현하기 위한 지식 모델을 제안한다. 행정구역은 국가의 영역을 국가 행정상의 목적에 따라 구분한 단위이다. 행정구역 지식모델은 지방자치법을 기준으로 행정구역체계의 구조, 행정단위별 관계를 정의한다. 둘째, 대한민국 행정구역 데이터에 대한 지식그래프를 소개한다. 공공 데이터를 의미적 수준에서 연결시키는 기준정보로써 행정구역 지식그래프의 특징과 이기종 공공데이터 연계 및 데이터 품질 개선을 위한 방법을 소개한다. 마지막으로 행정기관 데이터의 연계 결과를 통해 행정구역 지식그래프의 응용 방법을 살펴본다. 행정기관 명칭은 기관별로 상이하게 활용하고 있기 때문에 행정구역 그래프를 통한 데이터 식별 및 정제와 더불어 데이터 품질 개선에 효과적인 접근 방안으로 고려할 수 있다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제11권3호
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• pp.135-142
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• 2011

Unlike using the sequence-based representation for a chromosome in previous genetic algorithms for Bayesian structure learning, we proposed a matrix representation-based genetic algorithm. Since a good chromosome representation helps us to develop efficient genetic operators that maintain a functional link between parents and their offspring, we represent a chromosome as a matrix that is a general and intuitive data structure for a directed acyclic graph(DAG), Bayesian network structure. This matrix-based genetic algorithm enables us to develop genetic operators more efficient for structuring Bayesian network: a probability matrix and a transpose-based mutation operator to inherit a structure with the correct edge direction and enhance the diversity of the offspring. To show the outstanding performance of the proposed method, we analyzed the performance between two well-known genetic algorithms and the proposed method using two Bayesian network scoring measures.

• 한국정보과학회논문지:시스템및이론
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• 제31권10호
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• pp.603-609
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• 2004

절차적(procedural) 텍스쳐는 다양한 해상도로 텍스쳐 공간을 표현할 수 있으며, 매우 적은 저장 공간을 사용하는 장점을 가지고 있다. 그러나 절차적 표현을 위한 암시적(implicit) 방법을 이해하기 어렵고 프로그래밍에 익숙하지 않은 일반 사용자가 다루기 힘들다. 본 논문에서는 사용자의 직관적인 디자인작업을 통해 절차적 패턴을 자동으로 생성하는 인터랙티브 시스템이 제안된다. 전체 디자인 과정은 다중레이어(layer)를 기반으로 하며 데이타, 연산 및 출력 노드 등으로 구성된 그래프 구조로 표현된다. 제안된 시스템은 일반 사용자에게 유연한 인터페이스를 제공하여 프로그래밍 작업 없이 절차적 텍스쳐 쉐이더를 자동으로 생성하도록 한다. 시뮬레이션 결과로부터 제안된 방법이 다양한 패턴을 효과적으로 제작할 수 있음을 확인하였다.