Korean Air builds their schedules for these short connections (getting passengers from US/Europe to various Asian destinations quickly).

If it is very close, someone will be outside the plane with a sign and your name on it.

You can also show your itinerary to staff in transit security and they will let you cut the line if time is tight.

As the others said, as long as your ticket is one reservation together, you will be safe if you miss your flight. KE does have another evening flight to KIX, so presumably, they'll put you on that one. If you do find yourself waiting a while for the next flight, visit the 4th Floor Rest and Relax area...take a shower. Lounge Quality showers. toiletries provided of course, and completely free.