This year, you don't need an SAT score, because of covid. As an international student, you likely need a TOEFL score to establish proficiency in English. AP scores are always optional; a lack of them isn't great on your application, but it's not going to be a problem.
How are you the school president, vice president, AND secretary? It seems to me, as a neutral third party, that you just decided to found the student government and say you had every position in it.
Korean International Youth Olympiad could be a very strong extracurricular, depending on how selective it is. Same question goes for Asian-Korean Youth Summit. Your others are fairly good.
You have to be exceptional to get into Brown as an international student. Your chances are very low, and they would be even if you lived in the US. Your GPA and academic record aren't great, and you don't have AP's or SAT/ACT scores to help offset that.
Why, exactly, do you want to go to Brown? You don't seem to know very much about it, and you live halfway around the world.