[otrs] Generic Agent Web-interface and Cron job relationship

Dear all, I'm seeking clarification on the relationship between Generic Agent (set up via Web-interface) and Cron Job setting. As we can specify or set the Generic agent job to be run via Web interface, do we still need to set up the cron job to run the GenericAgent.pl? I had set up one Generic agent job (using web-interface)to delete the ticket that I had move it to Junk queue every 10:30 am Manday, without setting up cron job. It seem to me that the job never get execute by itself as the pre-config schedule (I can click Run Now to execute the job manually). Or if I have to set up the cron job to execute my Web-interface generic Agent job, can anyone give me the step to do so? With best regards Nuttapong