Pyong-oh worked as a veterinary lieutenant on the front and he left military service in 1956 as a captain and joined the South Korean Department of Agriculture.
He was appointed to a permanent position at the Kyung Hee University and in 1962 he went to Yale to work under Sidney Dillon Ripley.
[3] In 1965, a Daurian starling ringed by Won in Seoul was found and reported by his father.
He managed to smuggle a letter to his father through the assistance of Soviet ornithologist Leonid Portenko.
[3] In 2002, Won was finally granted permission to visit the North, although his parents and brother were then dead.