Formal:
* 저는 똑똑합니다. (jeo-neun ttok-ttok-hap-ni-da.) - This is the most formal way to say "I am smart" and is suitable for situations where you need to be polite, such as talking to someone older or in a professional setting.
* 저는 영리합니다. (jeo-neun yeong-ri-hap-ni-da.) - This is also a formal way to say "I am smart" and emphasizes intelligence and quick thinking.
Informal:
* 나는 똑똑해. (na-neun ttok-ttok-hae.) - This is a casual way to say "I am smart" and is appropriate for friends and family.
* 나는 영리해. (na-neun yeong-ri-hae.) - This is also a casual way to say "I am smart" and emphasizes intelligence and quick thinking.
More specific:
* 저는 머리가 좋습니다. (jeo-neun meo-ri-ga jo-seub-ni-da.) - This literally translates to "I have a good head" and implies intelligence and a good understanding.
* 저는 공부를 잘 합니다. (jeo-neun gong-bu-reul jal hap-ni-da.) - This means "I study well" and can be used to express that you are smart and good at learning.
Remember to choose the appropriate level of formality depending on the situation. You can also add other words to further express your meaning, such as "정말 (jeong-mal)" (really) or "꽤 (kkwae)" (quite).