Informal:
* 아직 안 자 (ajik an ja): This is the most common and straightforward way to say "not asleep yet."
* 아직 안 잤어 (ajik an jasseo): This is the same as the first option but slightly more polite.
* 아직 안 자요 (ajik an jayo): This is a polite way to say "not asleep yet." It's often used when talking to someone older or someone you don't know well.
Formal:
* 아직 취침하지 않았습니다 (ajik chwimchimhaji anhassseumnida): This is a very formal way to say "not asleep yet." It is usually used in writing or in formal settings.
Note:
* "Ajik" means "yet".
* "An" means "not".
* "Ja" means "to sleep".
You can choose the appropriate phrase depending on the situation and the level of formality you wish to use.