Yun, son of the poet Ki-Hyong Yun, studied music from 1933 on, in Tokyo and Osaka from 1939-1941. When Japan entered the Second World War, he returned to Korea and took part in his people’s struggle for liberation, being imprisoned by the Japanese occupants in 1943. 1946–1952 he taught at schools in Tongyong and Pusan, 1952–1956 at the universities of Pusan and Seoul. In 1955 he won the South Korean Culture Award. To establish contacts with the Western European avantgarde, in 1956 he went to Europe and was a pupil of Tony Aubin’s at the Conservatoire in Paris; after 1957 his teachers were Boris Blacher, Josef Rufer and Reinhard Schwarz-Schilling at the Musikhochschule West Berlin. He also took part in the Darmstadt courses. Since 1964 he lived in West Berlin. Because of his political involvement and a 1963 trip to North Korea he was kidnapped by the South Korean Secret Police in 1967 and brought to Seoul. Due to international pressure, he was released two years later. After his return to Western Germany he taught at the Musikhochschule Hannover and became a German citizen. Since 1970 he taught at the Musikhochschule West Berlin, from 1974–1985 as a Professor for Composition.