Korea (South) is 2.3 times larger than Rio de Janeiro (Brazil).
Area: 99,720 km2 World Factbook
Population: 49,039,986 (July 2014) World Factbook
South Korea, officially the Republic of Korea, is a country in East Asia, constituting the southern part of the Korean Peninsula. The name Korea is derived from Goryeo (also spelt Koryo), a dynasty which ruled in the Middle Ages. Wikipedia
Rio de Janeiro is one of the 27 states of Brazil. It has the third largest economy of Brazil, with the largest being that of the state of São Paulo, and the second being that of Minas Gerais. The state of Rio de Janeiro is located within the Brazilian geopolitical region classified as the Southeast. Wikipedia