KRW/USD transfers split cleanly: if the recipient has a Korean bank account, Wise is the cheapest option for most amounts. If they need cash in hand at a GS25 convenience store or a bank branch, use Remitly or WorldRemit. Traditional banks are the worst on rates but the easiest for first-time senders.
Disclaimer: informational only, not financial advice. Spreads and fees change; verify current rates with the provider.