Your Korean Air e-ticket will show 'Booking Class' along with other information for each segment of your ticket. It will also show 'Fare Basis', the first letter of which will also indicate the booking class. If you do not yet have an e-ticket, but are somewhere in the purchasing process, you should see a link to 'fare basis' following the flight details. Again, the first letter of the 3 or 4 letter code will indicate the booking class.