Per-transfer limit:
Korean nationals residing in Korea: No per-transfer limit as long as you stay within the annual limit (however, some receiving countries may have their own separate per-transfer limits).
Foreign nationals or Korean nationals not residing in Korea: 5,000 USD
Annual transfer limit:
Korean nationals residing in Korea: 100,000 USD
Foreign nationals or Korean nationals not residing in Korea: 50,000 USD
The annual transfer limit applies to the total amount the sender has sent over one year, regardless of the destination country. It also includes amounts sent through other overseas remittance providers or banks.
Notes
Auto-debit users can send up to KRW 10,000,000 per day.