There are travel credit cards that allow earning miles on all purchases and redeeming them with any airline. The Discover it Miles credit card is one of such cards. You will be able to earn 1.5 miles on all your purchases and redeem them with Asiana and other airlines without restrictions. The only requirement to redeem is your ticket should be bought with your Discover it Miles card. The card doesn’t have a traditional sign up bonus but Discover will match all miles you earn by the end of your first year. So basically, you will earn 3 miles your first year and 1.5 miles thereafter.