Use RDF to model a access control

Hi,

The Purpose is the development of a knowledge management system for
eGovernment. I research on the part how a process of controlled access can
be modelled by the use of RDF. Access controlling, it means that user are
identified and authenticated with their roles by the system.

I try to model this process with RDF schmea. I think, a appropriate ontology
sould be implemented.
I'm looking for any research, papers, case studies or other resources
related to my research. I would appreciate any pointer and your advice.
Thanks,
Eshaghi