Asiana Airlines provides STPC for those having forced overnight stopover.

Following passengers are not eligible for STPC:
1) Award tix holders
2) Voluntary overnight stopover pax
3) Pax doing overnight as earlier connecting flight was fully booked
4) OZ to *A or *A to OZ stopover (You chose to have this kind itinery)

The rule of thumb for STPC is that if you have a forced stopover greater than 8 hours, you may be eligible for STPC.

Nobody knows the specific rules regarding STPC hence it is advisable for you to do the following:

1. Check the eligibility of STPC above
2. Check the schedule of flights on www.staralliance.com to find out whether there is an earlier available connecting flight.
3. If you think you are covered, call OZ to find out whether you are eligible for STPC because if you ask on FT, nobody knows.