If you have reserved seating it will only show up on DL.Com as an assigned seat not available. For actual confirmation you need to call Korean Air, but once you know your assignment, DL.Com will show an "X" on your seat, but never show up as your's specifically. Interestly only reservations made on their website will show your seating assignment. Even if you made your reservations through KE ticketing office their website won't show your seating assignment on the "X" not available.
Apparently, they are back to only making seating assignments 30 days out, though I had a seating that was made some months ago and was good for our flight last week using Delta skymiles. You will need Korean's reservation number which Delta can usually give you. That's my best shot at my own experience. Once I had the seating assignment it was good on both segments... still have return flight to complete. By the way the seats included BE on the 380 from LAX to ICN... nice and very quiet flight we were in the forward most cabin.
By the way the window seats have some storage compartments (2 per row) that are great. Makes flying window seats rather nice.