Yoon was staff sergeant (posthumous) serving as an English translator in Afghanistan as a member of the Task Force Dasan, a dispatched engineering unit of the Republic of Korea Army.

The attack occurred at the front gate, where he was waiting to greet two local residents into the base.

Yoon is the first member of the Republic of Korea Armed Forces to be killed by enemy action since the Vietnam War.

He was dispatched to Afghanistan in September 2006, and was to return to South Korea on March 14, 2007, for a planned discharge in June.

He was promoted to staff sergeant and received the Inheon Order of Military Merit and the Bronze Star posthumously.