okay, the facts:
- koreans graduate middle school at 17 (kr age)
- he graduated middle school in feb 2012 (kr age 17)
- he started high school @ mokpo march 2012 but TRANSFERRED to seoul in oct 2012 (only in mokpo hs 7 months)
- the statement he was in mokpo hs for 2 yrs is FALSE

they graduate middle school and start high school in the same year (most of their academic calendars start in march), which is why he was 17 when he graduated.

i only mentioned age to deduce the year he graduated middle school.