1kBill is correct.
You'll get all of your boarding passes on check in at LAX. After landing at ICN follow the signs for connecting passengers, you will need to clear security and then take the short escalator to the departure level.
You may shop, grab a bite to eat, use the free wi fi hotspots, go upstairs to the lounges, shower or head to the gate 45 min. before departure.
Have a nice flight .