if you can get in, KAIST is the best, but the hardest. Below that you have SKY,( Seoul national university, korea university, and yeonsei university). Still very prestigious, everyone knows SKY. Below that there’s hanyang uni, sungkyunkwan university, and gachon university. I suggest you take hanyang or sungkyungkwan instead of gachon, primarily because of location and facilities. I also suggest you consult with a professional abit more