Their site says the following:
When traveling with Korean Air, Elite and Elite Plus members are entitled to one extra piece of luggage on all routes except transpacific routes for Elite members traveling Economy Class.
https://www.koreanair.com/ca/en/skyp...yteam-benefits
One of my friends flew them YYZ-ICN-SIN in Business as a Delta Silver Medallion (Skyteam Elite) member and received a third checked bag for free.