You need an ETA for Australia if you have a South Korean passport

Travelers need a travel authorization to visit Australia for Business or Tourism. Visa-exempt visitors entering Australia must obtain an Electronic Travel Authorization (eTA). Travelers can submit the eTA application online. Once the application is approved, travelers receive their eTA confirmation electronically. An eTA is linked electronically to a passport and is valid for up to 1 year. Travelers can stay in Australia for up to three months each time they enter the country. If travelers receive a new passport, they must apply for a new eTA. A valid eTA is required to board the flight. If the eTA is expired or doesn’t match the traveler’s passport information, travelers will not be able to board their flight.