South Korea was a nation-state on the Korean peninsula in east Asia on Earth. People or things originating from South Korea were commonly called South Koreans or Koreans.
Hahn Jun-Seok and his family emigrated from South Korea to the United States of America during his childhood. (Star Trek: The Prospect Chronicles: "Starry, Starry Night")
The Federation World of Warcraft Hall of Fame was located in the South Korean capital, Seoul, in the 2380s. (RIS Bouteina: "Rator III Awaits")