• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.333-351
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• 2002

This paper introduces a search method based on conceptual graph. A hyperlink information is essential to construct conceptual graph in web. The information is very useful as it provides summary and further linkage to construct conceptual graph that has been provided by human. It also has a property which shows review, relation, hierarchy, generality, and visibility. Using this property, we extracted the keywords of web documents and made up of the conceptual graph among the keywords sampled from web pages. This paper extracts the keywords of web pages using anchor text one out of hyperlink information and makes hyperlink of web pages abstract as the link relation between keywords of each web page. 1 suggest this useful search method providing querying word extension or domain knowledge by conceptual graph of keywords. Domain knowledge was conceptualized knowledged as the conceptual graph. Then it is not listing web documents which is the defect of previous search system. And it gives the index of concept associating with querying word.

• 인터넷정보학회논문지
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• 제16권5호
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• pp.39-47
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• 2015

그래프에서 각 노드에 대해 그래프 내의 중요도를 나타내는 중심성(centrality)을 계산할 수 있고, 그 값에 따라 각 노드는 중요도 순위(ranking)를 갖는다. 중심성을 나타내는 방법으로는 여러 척도가 있는데, 본 연구에서는 연결도(degree) 중심성, 밀접도(closeness) 중심성, 특성벡터(eigenvector) 중심성, betweenness 중심성에 국한하여 연구를 수행하였다. 본 연구는 그래프에서 에지를 하나 추가할 경우, 그래프 내 노드 전체에 미치는 노드의 중심성 및 순위의 변화를 실험계산을 통해 확인한다. 그리고, 추가되는 에지가 노드 전체의 중심성 및 순위에 미치는 영향은 그래프의 형태에 따라 달라진다는 것을 PCA(Principal Component Analysis)를 통해 밝혔다. 이 사실은 그래프의 구조적 특성을 구분하는 방법으로도 사용될 수 있다.

• Journal of Computing Science and Engineering
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• 제5권3호
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• pp.197-209
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• 2011

The increasing popularity of graph data, such as social and online communities, has initiated a prolific research area in knowledge discovery and data mining. As more real-world graphs are released publicly, there is growing concern about privacy breaching for the entities involved. An adversary may reveal identities of individuals in a published graph, with the topological structure and/or basic graph properties as background knowledge. Many previous studies addressing such attacks as identity disclosure, however, concentrate on preserving privacy in simple graph data only. In this paper, we consider the identity disclosure problem in weighted graphs. The motivation is that, a weighted graph can introduce much more unique information than its simple version, which makes the disclosure easier. We first formalize a general anonymization model to deal with weight-based attacks. Then two concrete attacks are discussed based on weight properties of a graph, including the sum and the set of adjacent weights for each vertex. We also propose a complete solution for the weight anonymization problem to prevent a graph from both attacks. In addition, we also investigate the impact of the proposed methods on community detection, a very popular application in the graph mining field. Our approaches are efficient and practical, and have been validated by extensive experiments on both synthetic and real-world datasets.

• 대한임베디드공학회논문지
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• 제9권1호
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• pp.11-16
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• 2014

When it comes to develop flight simulator, HAT (Height Above Terrain) is required to provide altitude information to the pilot who learns how to control an airplane in landing and takeoff situation. However, there might be inconsistent problem between real terrain and simulation information since current implementation of HAT simply depends on center of gravity point on the airplane. To overcome mentioned problem, in this paper, we propose how to obtain more accurate altitude information than existing scheme by making use of HAT and HOT (Height Of Terrain) information of landing equipments according to movement of the airplane. Moreover, we demonstrate the accuracy of the proposed scheme through new flight simulator developed through OSG(OpenSceneGraph) by taking example of terrain information for domestic airport.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.943-950
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• 2016

In this paper, we propose to analyze the physical characteristics of a planar dual-composite right-left handed transmission line by a common application of Bond Graph approach and Scattering formalism (Methodology S.BG). The technique, we propose consists, on the one hand, of modeling of a dual composite right-left metamaterial transmission line (D-CRLH-TL) by Bond Graph approach, and, it consists of extracting the equivalent circuit of this studied structure. On the other hand, it consists to exploiting the scattering parameters (Scattering matrix) of the DCRLH-TL using the methodology which we previously developed since 2009. Finally, the validation of the proposed and used technique is carried out by comparisons between the simulations results with ADS and Maple (or MatLab).

• 한국건설관리학회논문집
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• 제17권3호
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• pp.32-42
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• 2016

현재 국내 대부분의 토목 건축 구조물이 BIM 정보가 부재한 상황에서 준공 BIM(as-built BIM)의 수요가 점차 증가하고 있다. 준공 BIM 구축을 위한 공간자료 취득에는 고밀도의 포인트 클라우드를 생성할 수 있는 레이저 스캐너가 주로 활용되고 있다. 하지만 기존의 고정식 스캔 시스템은 이동이 번거롭고, 정밀한 위치 선정이 필요 하며, 스캔 자료 정합을 위해 별도의 표지를 설치하거나 공액점을 추출하는 과정이 필요하다. 본 연구에서는 수작업을 최소화하기 위해 기존의 고정식 스캔 시스템을 대체할 수 있는 이동식 스캔 시스템을 제안하고자 하며, 기반 기술로 graph-based SLAM을 적용하였다. 테스트 장비는 총 세 개의 2차원 스캐너를 탑재하고 있으며, 중앙의 한 개는 수평으로 설치되어 graph 구축을 통한 이동경로취득에 사용되었고, 좌우 두 개는 수직으로 설치되어 시스템 진행의 연직 방향으로 주변 구조물에 대한 3차원 스캔 정보 취득에 사용되었다. 개발된 graph-based SLAM은 이동경로 상에 누적된 위치오차를 해소하기 위한 loop closure 처리 방법으로 Adaboost 기계학습을 적용하였다. 이는 특히 본 연구에서 사용한 장비와 같이 기계학습을 위한 다수의 feature 정보를 제공할 수 있는 멀티 스캐너 시스템에 적합한 방식이며, 두 실내공간을 대상으로 한 테스트에서 단일 스캐너 대비 false positive rate를 각각 7.9% 및 13.6%까지 줄일 수 있었다. 최종적으로 연구대상지역의 2차원 및 3차원 지도 구축을 통해 개발된 graph-based SLAM의 효용성을 확인하였다.

• Journal of applied mathematics & informatics
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• 제32권1_2호
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• pp.255-266
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• 2014

For a connected graph G = (V,E) of order at least two, a set S of vertices of G is a monophonic set of G if each vertex v of G lies on an x - y monophonic path for some elements x and y in S. The minimum cardinality of a monophonic set of G is the monophonic number of G, denoted by m(G). Certain general properties satisfied by the monophonic sets are studied. Graphs G of order p with m(G) = 2 or p or p - 1 are characterized. For every pair a, b of positive integers with $2{\leq}a{\leq}b$, there is a connected graph G with m(G) = a and g(G) = b, where g(G) is the geodetic number of G. Also we study how the monophonic number of a graph is affected when pendant edges are added to the graph.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.529-532
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• 1988

This paper proposes a graph matching algorithm based on simulated annealing, which assures the globally optimal solution for circuit partitioning for the placement in the rectilinear region occurring as a result of the pre-placement of some macro cells, or onto the nonplanar surface in some military or space applications. The circuit graph ($G_{C}$) denoting the circuit topology is formed by a hierarchical bottom-up clustering of cells, while another graph called region graph ($G_{R}$) represents the geometry of a planar rectilinear region or a nonplanar surface for circuit placement. Finding the optimal many-to-one vertex mapping function from $G_{C}$ to $G_{R}$, such that the total mismatch cost between two graphs is minimal, is a combinatorial optimization problem which was solved in this work for various examples using simulated annealing.

• 로봇학회논문지
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• 제19권2호
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• pp.196-202
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• 2024

The ability to understand given environments and plan a sequence of actions leading to goal state is crucial for personal service robots. With recent advancements in deep learning, numerous studies have proposed methods for state representation in planning. However, previous works lack explicit information about relationships between objects when the state observation is converted to a single visual embedding containing all state information. In this paper, we introduce graph-based state representation that incorporates both object and relationship features. To leverage these advantages in addressing the task planning problem, we propose a Graph Neural Network (GNN)-based subgoal prediction model. This model can extract rich information about object and their interconnected relationships from given state graph. Moreover, a search-based algorithm is integrated with pre-trained subgoal prediction model and state transition module to explore diverse states and find proper sequence of subgoals. The proposed method is trained with synthetic task dataset collected in simulation environment, demonstrating a higher success rate with fewer additional searches compared to baseline methods.

• East Asian mathematical journal
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• 제35권1호
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• pp.17-22
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• 2019

A travel groupoid is a pair (V, ${\ast}$) of a set V and a binary operation ${\ast}$ on V satisfying two axioms. For a travel groupoid, we can associate a graph in a certain manner. For a given graph G, we say that a travel groupoid (V, ${\ast}$) is on G if the graph associated with (V, ${\ast}$) is equal to G. There are some results on the classification of travel groupoids which are on a given graph [1, 2, 3, 9]. In this article, we introduce the notion of vertex-indexed partition systems on a graph, and classify the travel groupoids on the graph by the those vertex-indexed partition systems.