score:2
Delta has an interline agreement for ticketing and baggage with Asiana. See: https://pro.delta.com/content/agency/gb/en/policy-library/reservations-and-ticketing/interline-electronic-ticketing-agreements--iet-.html This will cover your baggage, you need to ask at check-in to have your bags checked through to DEL.
Second get both boarding passes at check-in in SEA. They may say to you you need collect second boarding pass at Transfers gate (airside) in Korea. In which case go to the Asiana transfers counter at ICN. You do not need to clear customs/immigration to transfer At ICN.