Seoul University Admission

Hi! I am going to be a sophomore in high school soon. My freshman year grades weren’t very good overall ( 2 As and 4 Bs). I even failed some tests, but managed to pull my grades up at the end. If I manage to drastically improve my grades for sophomore, junior and senior year, like all As, do you think I will have a chance to apply for Seoul University? They do ask for your high school transcripts and I am worried that they might turn me down for my grades when I was 13 and 14 years old. I will turn 15 this year and I know it may be a little too early to start worrying about college, but Seoul University is my dream university and I was wondering if not studying hard enough at 13 and 14 years old would affect my overall admission?