For a large scale software development project, requirements and design artifacts like UML models are increasingly produced and collected in a software repository and can be later reused for new software development projects. The purpose of this paper is to analyze and visualize the dependencies in these artifacts to help software developers to see some interesting structural patterns. We adopt the techniques of social network analysis to do this purpose. This paper focuses on use case model artifacts and proposes the way to represent use case models as relation networks, i.e., system, use case, actor, system-use case, actor-use case, and system-actor networks. To demonstrate our work, a hospital software project is used as a case study.