I get up at 4am and try and be back before 11am. That way the worst of the heat is avoided. It does mean that after about 9am the pace suffers and I have to drink A LOT of water, but it can be done in the middle of a Korean Summer.
http://www.endomondo.com/workouts/lVF25LmgVRA
Todays ride... luckily it was overcast and that helped, but the pace did suffer compared to a cooler. day.