use sys as user to dump file in oracle database

impdp userid=\'/ as sysdba\' schemas=test dumpfile=test.dump logifle=test.log directory=data_pump_dir

in windows
expdp userid="'/ as sysdba'"  

reference:
http://mytechnicalthoughts.wordpress.com/2012/08/25/how-to-run-the-oracle-data-pump-command-as-sysdba/