The Verdict: Need More Info
Your age fits, but we could not confirm that Brazil is issuing the inbound visa to Korean nationals. Ask a Brazilian consulate in Korea whether it is, and under what quota.
Brazil's foreign ministry lists an agreement with South Korea in force, running to age 34, and describes the agreements as working both ways. One listing of the inbound Brazilian visa omits Korea, and we could not resolve that from official sources.
If it is being issued, expect to need a valid passport, a return ticket or the means to buy one, funds for the first period, and health cover. The visa must be obtained before you travel.