Eventually his father relented once Yun agreed to enroll in a business school while continuing his musical studies.

When the Pacific War began in December 1941, he moved back to Korea where he participated in the Korean independence movement.

Yun was interned at Keijō Imperial University Hospital for complications resulting from tuberculosis when Korea was liberated from Japanese rule in August 1945.

He received the Seoul City Culture Award in 1955, and traveled to Europe the following year to finish his musical studies.

The premiere of his oratorio Om mani padme hum in Hanover 1965 and Réak in Donaueschingen (1966) gave him international renown.

However, due to alleged acts of espionage, he was kidnapped by the South Korean secret service from West Berlin on 17 June 1967.

[4] A worldwide petition led by Guenter Freudenberg and Francis Travis was presented to the South Korean government, signed by approximately 200 artists, including Luigi Dallapiccola, Hans Werner Henze, Heinz Holliger, Mauricio Kagel, Herbert von Karajan, Joseph Keilberth, Otto Klemperer, György Ligeti, Arne Mellnäs, Per Nørgård, Karlheinz Stockhausen, Igor Stravinsky, and Bernd Alois Zimmermann.

Among his students are Kazuhisa Akita, Jolyon Brettingham Smith, In-Chan Choe, Conrado del Rosario, Raymond Deane, Francisco F. Feliciano, Masanori Fujita, Keith Gifford, Holger Groschopp, Toshio Hosokawa, Sukhi Kang, Chung-Gil Kim, Wolfgang Klingt, Erwin Koch-Raphael, Isao Matsushita, Masahiro Miwa, Hwang-Long Pan, Martin Christoph Redel, Byong-Dong Paik, Bernfried Pröve, Takehito Shimazu, Minako Tanahashi, Masaru Tanaka, Michail Travlos, Jürgen Voigt, and Michael Whticker.

Yun promoted the idea of a joint concert featuring musicians from both Koreas in Panmunjom, which failed in 1988, but South Korean artists could be invited to Pyongyang in 1990.

Yun was invited to attend a festival of his music in South Korea in 1994, but the trip was broken off after internal and external conflicts.

[5] When Oh's wife Shin Suk-ja and her little daughters were imprisoned in Yodok camp, Yun helped them and took photos and a tape from North Korea to Berlin.

After experimenting with 12-tone techniques Yun developed his own musical personality beginning in his post-serialistic "sound compositions" of the early 1960s.