You should be fine. You didn't stop and enter HKG, so your flight is direct. Remember, the majority don't take nonstop flights. You have an Aussie resident card and you're going to a third country.
This is from the Immigration website:
Applicable to…
Persons holding a visa (re-entry permit, permanent residency, etc.) to enter the U.S. (including Guam and Saipan), Canada, Australia, or New Zealand (hereinafter referred to as "the four advanced countries")
1) who transit through Korea to go to one of the four advanced countries.
2) who stay in one of the four advanced countries and take a direct flight from the country to Korea to go to a country of origin or a third country.
If you hold an e-visa to Australia and a visa label is attached to your passport, you are permitted to enter Korea without a visa. However, if the label is not on your passport, you are granted no-visa entry only when you depart from Australia and transit through Korea.
You'd be #2. Stay in Australia, direct flight from there to Korea (also, think, not everyone takes nonstops...) and you're going to said 3rd country, China. Even with that e-visa in the passport rule, it doesn't matter. You're following the rules "From Australia to another country through Korea." You'll be fine.
As always, just call your consulate to double check the rules.
http://www.hikorea.go.kr/pt/InfoDeta...showMenuId=375