• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.5
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• pp.564-568
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• 2011

Microblogs became popular information delivery ways due to the spread of smart phones. They have the characteristic of reflecting the interests of users more quickly than other medium. Particularly, in case of the subject which attracts many users, microblogs can supply rich information originated from various information sources. Nevertheless, it has been considered as a hard problem to obtain useful information from microblogs because too much noises are in them. So far, various methods are proposed to extract and track some subjects from particular documents, yet these methods do not work effectively in case of microblogs which consist of short phrases. In this paper, we propose a graph-based topic extraction and partitioning method to understand interests of users about a certain keyword. The proposed method contains the process of generating a keyword graph using the co-occurrences of terms in the microblogs, and the process of splitting the graph by using a network partitioning method. When we applied the proposed method on some keywords. our method shows good performance for finding a topic about the keyword and partitioning the topic into sub-topics.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.378-391
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• 2010

The purpose of this study was to investigate the graph interpretation ability and perception of high school students and preservice secondary teachers in Earth science. We developed two different instruments; one was a graph interpretation ability inventory that consists of 9 graph types with 18 items, and the other one is two questionnaires to explore the participants' perception about Earth science-related graph. The results of this study are as follows: High school students and preservice secondary teachers demonstrated their remarkable ability in interpreting a line graph, but showed their limited ability with the graph of overlapped and directional change, which means the graph interpretation ability was affected by a graph type; two groups participated in this study revealed a considerable difference in the graph interpretation ability depending on the grade level; preservice teachers were superior to high school students in discriminating two graphs, the representation method, which are different with the same topic; and many participants in both groups considered that the property of Earth science graph was considerably different from that of other science subjects, especially in directional change graph, scatter graph, contour map, and domain graph. The results suggest that the effective graph instruction strategies be developed in Earth science learning.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.205-214
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• 2016

As a large amount of graph-structured data is widely used in various applications such as social networks, semantic web, and bio-informatics, keyword-based search over graph data has been getting a lot of attention. In this paper, we propose an efficient method for keyword search over graph data to find a set of top-k answers that are relevant as well as non-redundant in structure. We define a non-redundant answer structure for a keyword query and a relevance measure for the answer. We suggest a new indexing scheme on the relevant paths between nodes and keyword terms in the graph, and also propose a query processing algorithm to find top-k non-redundant answers efficiently by exploiting the pre-calculated indexes. We present effectiveness and efficiency of the proposed approach compared to the previous method by conducting an experiment using a real dataset.

• The Transactions of the Korea Information Processing Society
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• v.6 no.7
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• pp.1805-1816
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• 1999

This paper presents the Module Class Dependency Graph for expressing the dependency relations between classes effectively. The object-oriented language is developed independently at design time, and consists of relationship between classes. Therefore we need to consider these characteristics of independence, and to express effectively the relation of classes which is existed in class hierarchy. In the System Dependence Graph and Class Dependence Graph, the relationship of classes is not expressed. To express the class relationship, we propose the Module Class Dependence Graph, and we verify the effectiveness of this method applying to object constructor, inheritance relationship and dynamic binding. Also, we presents the expressing method of parameter to identify the member data of classes. Using this Module Class Dependency Graph, we can analyze the relationship of module class correctly at design time. This method can be applied to reverse engineering, testing, visualization and other various fields to analyze system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1939-1944
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• 2003

This paper presents a global path planning algorithm based on a visibility graph method, and applies additionally various constraints for constructing the reduced visibility graph. The modification algorithm for generating the rounded path is applied to the globally shortest path of the visibility graph using the robot size constraint in order to avoid the obstacle. In order to check the visibility in given 3D map data, 3D CAD data with VRML format is projected to the 2D plane of the mobile robot, and the projected map is converted into an image for easy map analysis. The image processing are applied to this grid map for extracting the obstacles and the free space. Generally, the tree size of visibility graph is proportional to the factorial of the number of the corner points. In order to reduce the tree size and search the shortest path efficiently, the various constraints are proposed. After short paths that crosses the corner points of obstacles lists up, the shortest path among these paths is selected and it is modified to the combination of the line path and the arc path for the mobile robot to avoid the obstacles and follow the rounded path in the environment. The proposed path planning algorithm is applied to the mobile robot LCAR-III.

• Journal of KIISE:Software and Applications
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• v.31 no.3
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• pp.267-275
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• 2004

Directed graph and Lindenmayer system (L-system) are two major encoding methods of representation to develop creatures in application field of artificial life. It is difficult to define real morphology structurally using the L-systems which are a grammatical rewriting system because L-systems represent genotype as loops, procedure calls, variables, and parameters. This paper defines a class of representations called structured directed graph, which is identified by its ability to define structures of the genotype in the translation to the phenotype, and presents an example of creating 3D flowers using a directed graph which is proper method to represent real morphology, and interactive genetic algorithm which decodes the problem with human's emotional evaluation. The experimental results show that natural flower morphology can be generated by the proposed method.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.2
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• pp.216-226
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• 2000

This paper presents a new method to synthesize timed asynchronous circuits directly from the specification without generating a state graph. The synthesis procedure begins with a deterministic signal transition graph specification with timing constraints. First, a timing analysis extracts the timed concurrency and timed causality relations between any two signal transitions. Then, a hazard-free implementation under the timing constraints is synthesized by constructing a precedence graph and finding paths in the graph. The major result of this work is that the method does not suffer from the state explosion problem, achieves significant reductions in synthesis time, and generates circuits that have nearly the same area as compared to previous methods.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1013-1016
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• 1998

A method for generation of design verification tests from behavior-level VHDL program is presented. Behavioral VHDL programs contain multiple communicating processes, signal assignment statements. So for large, complex system, it is difficult problem to test or simulation. In this paper, we proposed a new hardware design verification method. For this method generates control flow graph(CFG.) and process modeling graph(PMG) in the given under the testing VHDL program. And this method proved very effective that all the assumed design errors could be detected.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.101-105
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• 1999

The goal of this paper is to present instantaneous compensating power flow of active power filters(APFs) by graphical method that could be practicable to compensate the power in both case of behaving in instantaneous rectifying mode and instantaneous inverting mode. To ensure the validity of the proposed method, computer simulation is achieved. Proposed method can be present more exquisite and physically meaningful power flow than conventional method in instantaneous compensating power flow Graph of APFs.

• Communications of the Korean Mathematical Society
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• v.18 no.4
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• pp.745-754
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• 2003

Maximum clique problem is to find a maximum clique(largest in size) in an undirected graph G. We present a method that computes either a maximum clique or an upper bound for the size of a maximum clique in G. We show that this method performs well on certain class of graphs and discuss the application of this method in a branch and bound algorithm for solving maximum clique problem, whose efficiency is depended on the computation of good upper bounds.