The nearest airports are Düsseldorf and Dortmund. There are direct train connections between Düsseldorf Airport and Bochum Central Station. The train journey takes between 35-40 minutes. Possible train connections can be found on the Deutsche Bahn website.
From Bochum Hauptbahnhof please take the underground line U35 (direction "Hustadt") to the campus of the Hochschule Bochum. The exit is at the station "Lennershof". The walk to Bochum University is approxametly 5-10 minutes. [Video: Fußweg von der U35-Haltestelle "Lennershof" zur Hochschule Bochum]
Further information on how to get to Bochum University of Applied Sciences can be found here.