Originally Posted by
royng
I've found from my archive of photos a banner explaining the service I mentioned. However, to make use of this service (for free 5 days) you must be taking
KE international flight (based on my limited proficiency of Korean).
So, I believe
bobbybrown (post#2) is right. Asiana very probably had offered the same service too.

This KE banner states to check the coat at Hanjin Delivery Service, so one of the two luggage service companies at ICN. It seems it's really the same coat check service these companies offer, just courtesy of the airline during the promotional period.