Original: Ban was appointed Ambassador to Austria in 1998 , and a year later he was also elected as Chairman of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization ( CTBTO PrepCom ) .
Simplified: While he served as Ambassador to Austria , Ban was elected as Chairman of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization ( CTBTO PrepCom ) in 1999 .