The requested vessel with name YOSU and MMSI:0 and IMO:5396399 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
YOSU GAS 9016739 440831000 YEOSU Sep 26, 2017 01:38 UTC
YOSUN N/A 271040493 May 30, 2017 16:03 UTC
YOSUN-53 N/A 271042113 Aug 30, 2013 13:51 UTC

Also, you may try to find the vessel in our comprehensive Vessels Database or track this ship on the map.