Yeh, Australia will sting you for the tax on your Korean earnings too. There is an agreement to not take tax twice on the same money, but because you're not paying Korean tax, that means your money is taxed by Australia instead. So while normally you should have gotten a refund, you're being taxed on the Korean money, cancelling that refund out.
A few years ago I got an Australian accountant to do my tax return for me, I didn't think I would pay tax in Australia for Korean wages. She told me I had to. My situation was a lot like yours, with half a year worked in Australia. I got a tiny return the first tax return and ended up with a huge tax bill my first full year here.
I should say that I still disagree with her assessment, and I'm going to look into it again when I have some free time and the patience to look around the ATO site for information. Maybe I can have it re-assessed. Point being, get a professional to look at it if you're concerned.
I'm no accountant though, and I still hate tax.