• Journal of KIISE
• /
• v.44 no.10
• /
• pp.1034-1044
• /
• 2017

Although traversal strategies are important for the performance of model checking, many studies have ignored the impact of traversal strategies in model checking with a block-encoded abstract reachability graph. Studies have considered traversal strategies only for an abstract reachability graph without block-encoding. Block encoding plays a crucial role in the model checking performance. This paper therefore describes Dual-traversal strategy, a simple and novel technique to control traversal strategies in a block-encoded abstract reachability graph. This method uses two traversal strategies for a model checking, one for effective block-encoding, and the other for traversal in an encoded abstract reachability graph. Dual-traversal strategy is very simple and can be implemented without overhead compared to the existing single-traversal strategy. We implemented the Dual-traversal strategy in an open source model checking tool and compare the performances of different traversal strategies. The results show that the model checking performance varies from the traversal strategies for the encoded abstract reachability graph.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.5
• /
• pp.940-948
• /
• 2007

Many real world problems can be modeled as a graph and traversals on the graph. The structure of Web pages can be represented as a graph, for example, and user's navigation paths on the Web pages can be model as a traversal on the graph. It is interesting to discover valuable patterns, such as frequent patterns, from such traversals. In this paper, we propose an algorithm to discover frequent traversal patterns when a directed graph and weighted traversals on the graph are given. Furthermore, we propose a performance enhancement by traversal split and then verify it through experiments.

• KIISE Transactions on Computing Practices
• /
• v.23 no.8
• /
• pp.492-497
• /
• 2017

A hypergraph consists of a set of nodes and hyperedges that connect an arbitrary number of nodes. We employ graph traversal algorithms such as BFS and DFS to analyze or explore hypergraph data. However, the conventional BFS and DFS do not consider the structural characteristics of hyperedges. In this paper, we propose a method to record visited edges and nodes during the traversal algorithm for data stored in hypergraphDB. In the experiments, we conduct various hypergraph analyses that utilize traversal algorithms and show that our method achieves a fewer number of database accesses and faster processing time than the conventional one.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.4
• /
• pp.926-937
• /
• 1996

A graph traversal technique is a certain pattern of visiting nodes of a graph. Many special traversal techniques have been applied to solve graph related problems. For example, the depth first search technique has been used for finding strongly onnected components of a directed graph or biconnected components of a general graph. The distributed protocol to implement his depth first search technique on the distributed network can be divided into a fixed topology problem where there is no topological change and a dynamic topology problem which has some topological changes. Therefore, in this paper, we present a more efficient distributed depth first search protocol with fixed topology and a resilient distributed depth first search protocol where there are topological changes for the distributed network. Also, we analysed the message and time complexity of the presented protocols and showed the improved results than the complexities of the other distributed depth first search protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.3 no.6
• /
• pp.612-627
• /
• 2009

The high-level contribution of this paper is to illustrate the effectiveness of using graph theory tree traversal algorithms (pre-order, in-order and post-order traversals) to generate the chain of sensor nodes in the classical Power Efficient-Gathering in Sensor Information Systems (PEGASIS) data aggregation protocol for wireless sensor networks. We first construct an undirected minimum-weight spanning tree (ud-MST) on a complete sensor network graph, wherein the weight of each edge is the Euclidean distance between the constituent nodes of the edge. A Breadth-First-Search of the ud-MST, starting with the node located closest to the center of the network, is now conducted to iteratively construct a rooted directed minimum-weight spanning tree (rd-MST). The three tree traversal algorithms are then executed on the rd-MST and the node sequence resulting from each of the traversals is used as the chain of nodes for the PEGASIS protocol. Simulation studies on PEGASIS conducted for both TDMA and CDMA systems illustrate that using the chain of nodes generated from the tree traversal algorithms, the node lifetime can improve as large as by 19%-30% and at the same time, the energy loss per node can be 19%-35% lower than that obtained with the currently used distance-based greedy heuristic.

• The KIPS Transactions:PartD
• /
• v.9D no.3
• /
• pp.337-344
• /
• 2002

Recently, there has been a lot of research on graph-type data because it can model seamless the application domains such as GIS, network, WWW, multimedia presentations etc., and domain in which the data sequence is important. In this paper, an efficient code system, called node code system, is proposed to evaluate paths of DAG in a multimedia presentation graph. The node code system assigns a unique binary string to each node of a graph. The comparison of node codes of two nodes tells the connectivity between the nodes without actual traversal of a graph. The method using the property of the node code system allows us to construct the paths between two nodes more efficiently than the method using conventional graph traversals. The algorithms to construct paths using the node code system are provided.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04b
• /
• pp.514-516
• /
• 2002

3D 가상공간 사용자의 몰입감과 임장감에 결정적인 영창을 미치는 상호작용기법은 공간 네비게이션과 객체조작기법으로 나눌 수 있다. 그중 정교한 객체조작이 요구되는 특정분야에서는 보다 효과적인 객체조작기법이 절실히 요구된다. 본 논문에서는 객체를 구성하는 장면 그래프 구조를 사용자의 선택에 따라 내부적으로 분할하여 재구성한 선택트리의 순회를 통해 객체의 세부 단위요소를 선택하고 이를 조작하며 선택을 해제를 할 수 있는 일련의 기법을 제안한다. 제안된 기법은 정교한 객체의 조작을 필요로 하는 분야의 3D 사용자 인터페이스 구축에 효과적으로 적용될 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.3
• /
• pp.633-652
• /
• 2024

Software testing is an important phase as it ensures the software quality. The software testing process comprises of three steps: generation, execution, and evaluation of test cases. Literature claims the usage of single and multiple 'Unified Modeling Language' (UML) diagrams to generate test cases. Using multiple UML diagrams increases test case coverage. However, the existing approaches show limitations in test case generation from UML diagrams. Therefore, in this research study, we propose an approach to generate the test cases using UML State Chart Diagram (SCD), Activity Diagram (AD), and Sequence Diagram (SD). The proposed approach transforms UML diagrams into intermediate forms: SCD Graph, AD Graph, and SD Graph respectively. Furthermore, by integrating these three graphs, a System Testing Graph (STG) is formed. Finally, test cases are identified from STG by using a traversal algorithm such as Depth First Search (DFS) that is an optimization method. The results show that the proposed approach is better compared to existing approaches in terms of coverage and performance. Moreover, the generated test cases have the ability to detect faults at the unit level, integration, and system level testing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.05a
• /
• pp.22-24
• /
• 2022

Recently, Graph Database (GDB) is being used in wide range of industrial fields. GDB is a database system which adopts graph structure for storing the information. GDB handles the information in the form of a graph which consists of vertices and edges. In contrast to the relational database system which requires pre-defined table schema, GDB doesn't need a pre-defined structure for storing data, allowing a very flexible way of thinking about and using the data. With GDB, we can handle a large volume of heavily interconnected data. A network service provider provides its services based on the heavily interconnected communication network facilities. In many cases, their information is hosted in relational database, where it is not easy to process a query that requires recursive graph traversal operation. In this study, we suggest a way to store an example set of interconnected network facilities in GDB, then show how to graph-query them efficiently.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2001.11a
• /
• pp.585-589
• /
• 2001

최근 그래픽 하드웨어의 성능향상과 인터넷의 발전으로 이를 기반으로 하는 인터렉티브 3D 그래픽스와 데스크탑 가상환경 분야에 대한 관심이 높아지고 있다. 그러나 데스크탑 가상환경에서 객체의 조작과 관련된 3D 사용자 인터페이스에 대한 성공적인 연구사례는 찾아보기 힘들다. 그 이유는 하드웨어적인 제약과 더불어 3D 공간상의 객체를 2D상에서 조작함으로써 발생하는 인지적인 문제해결이 어렵기 때문이다. 이의 해결을 위해 본 논문에서는 객체를 구성하는 장면 그래프를 내부적으로 분할하여 생성된 서브트리의 순회를 통해 객체의 세부 단위요소를 쉽게 선택하고 해제하는 일련의 객체조작 기법을 제안한다. 또한 각 조작단계에서 사용자의 의사결정을 돕는 다양한 시각 피드백 기능을 함께 지원한다. 제안된 기법은 정교한 객체의 조작을 필요로 하는 분야의 3D 사용자 인터페이스 구축에 매우 효과적으로 적용될 수 있음을 확인하였다.