NotebookLM (AI Notes from Your Own Sources)
A Google service; opening the address brings up a Google account sign-in screen first. The sign-in screen is available in Korean and many other languages.
How to try it
Opening the address shows a Google sign-in screen, so you must log in with your account to use it. Because it works from documents you provide, files you upload go to the operator's servers. A Google account login is required.