I believe they reserve the bulkhead seats for mothers with their children or people who need more space like handicapped people as well. My mom actually came back on the JFK-ICN leg last night and she told me she sat in the bulkhead seat. She was assigned the seat at ICN and she came 4 hours before her flight to the airport. Not sure but maybe her Diamond status was a kicker?

So, I guess your best chance is to arrive really early and request it.