Aren't those LAX-ICN codeshare on KE metal? I didn't think Delta has a LAX-ICN flight.. and the JFK-ICN is codeshare on KE metal also. So with the tpac leg on KE, I'd just go with JFK-ICN-SIN instead of adding a stop and flying out to LAX... and would still get the D1 lounge access in JFK.