# OLGAVis: On-Line Graph Analysis and Visualization for Bibliographic Information Network
## 5 Comparison of Graph Visualization Tools  
Graph visualization tools addressing the bibliographic data include VOSViewer ([[https://www.vosviewer.com/](https://www.vosviewer.com/)]([https://www.vosviewer.com/](https://www.vosviewer.com/)) (accessed on 16 April 2021)), and CitationNetworkExplorer ([[https://www.citnetexplorer.nl/](https://www.citnetexplorer.nl/)]([https://www.citnetexplorer.nl/](https://www.citnetexplorer.nl/)) (accessed on 16 April 2021)), which were developed by the same organization. These tools were developed for visualization and analysis of publication statistics and citation networks, which provide a clustering function that is based on the citation relationship and keywords of the paper. However, these tools cannot be deemed as a visualization tool for an exploratory analysis based on a heterogeneous information network model that addresses all of nodes, relationships, and attributes.  
There have been studies on OLAP analysis and visualization tools of bibliographic data. A study [3] investigated the design of a relational database schema for OLAP analysis of bibliographic data, SQL query for OLAP operation, and data warehouse construction. The MDX Query of MS-SQL was used and the result was visualized with tables and charts of MS Excel, which cannot be regarded as a GUI tool.  
Another research [15], which developed an OLAP cube-based graph visualization tool for bibliographic data, constructed sub-networks, such as co-author networks, citation networks, and topic networks from the DBLP data, and further developed a graph visualization tool that reinforced cube processing on nodes and edges. The same research investigated the graph cube generation and graph-oriented operation of OLAP operators, such as Roll-up and Drill-down. The graph database Neo4j was used for data storage, but there was no mention of storage schema modeling.  
Figure 10: ‘Author-Paper’ BIN created using GetConnotation operator.  
Figure 9: Notations for Visualization. Tool.  
Although a number of studies addressing an analysis based on graphs or information networks of bibliographic data have been conducted, there are only a few studies that have developed tools as a result of the research, or that intended to develop a GUI tool. The Table 2 shows a comparison of the graph visualization studies on the bibliographic data.  
The first research [3] in the table is a bibliometric study, which visualized the results of analysis with MDX Query and MS Excel, not a study on GUI tool development. The second research [16] is related to a bibliographic data visualization tool, which is serviced under the name of VOSViewer. This is a tool in the bibliometric network field, which conducted a clustering analysis that was based on citation and co-author relationships. The third research [15] is a heterogeneous information network visualization tool that performs OLAP and cube-based operations, which is a GUI tool that does not have keyword search or link navigation functions for the result network.  
The visualization tool that is proposed in this research has great significance, in that a complete heterogeneous information network has been modeled that considers all relationships and attributes between major entities that compose complex bibliographic data, and explanatory entities that are directly connected to the papers. Furthermore, this research is also significant in that this tool can use the graph database to improve the development efficiency of relationship-oriented services and, unlike other GUI tools, this tool is capable of keyword search, link navigation, exploratory browsing that provides node expansion, and graph aggregation.