If you're looking for an alternative to Seoul when visiting South Korea, Busan is definitely worth considering. This sprawling port city is the largest of its kind in the world, with a thriving industrial sector, dynamic arts and cultural scene, not to mention gorgeous stretches of coastline and beautiful beaches.
Effective March 25, 2018, Asiana Airlines is now offering 2 daily flights from Seoul (Incheon) to Busan, connecting from their U.S. gateways all the way through.
Incheon-Busan
-OZ8533/Daily/Aircraft A320/Departure: 6:30am/Arrival: 7:30am (as of March 25, 2018)
-OZ8531/Daily/Aircraft A320/Departure: 19:20pm/Arrival: 20:20pm (as is)
Busan-Incheon
-OZ8532/Daily/Aircraft A320/Departure: 7:00am/Arrival: 8:00am (as is)
-OZ8534/Daily/Aircraft A320/Departure: 18:30pm/Arrival: 19:30pm (as of March 25, 2018)