Originally Posted by mikesaidyes

You *should* be ok but it will be tight. Finnair uses main T1 gate - but immigration lines *might* be long at 9 AM (southeast Asia flights arrive then). Typically, though, most connect from those flights or it's local Koreans. Baggage claim and customs is easy, literally just grab and go.

The problem is that Eastar has no transfer counter, no online check in for international....so you have to get out of the airport and go up to check in and complete it by 10:30. Korean airlines and airport staff are generally friendly and will help you skip lines if tight (show your itinerary).

Going back through airport T1 will be kind of busy in morning time on weekdays (I waited like 10-15 mins in security when I just went through T1 a few weeks ago in the AM at like 8-9 AM)