I'm studying semantic web and I'd like to use different ontologies to enrich my raw sensor data. I'm using Protégé. Imagine I want to use concepts from three different ontologies (for instance SSN, CSSO and another), have I to merge (in Protege - Refactor-> Merge Ontologies) all ontologies in protege? If I need to use only a part of these ontologies? (some ontologies are really big!)
I'm a newbie in this field and I would like to know the correct way to do.