The Embassy of the Republic of Korea represents Korea in Australia. This office offers updated information on Korea and their relations with Australia.
From 1 June 2014, an Australian passport holder is allowed to enter Korea and stay up to 90 days without an entry visa if the purpose of your visit is Transit, Tourism, Conference or Business meeting. You must have a valid Australian passport and outbound air/ferry-ticket confirming your departure from Korea within 90 days from the date of entry.
Always cross check visa information on their website before making travel arrangements.