Whether someone born in 2005 can drink legally in Korea depends on the year and the specific date. The answer changes from year to year.
According to the Korean age system, which is different from the international age system, as of the end of 2023, those born in 2005 can purchase and consume alcohol starting from January 1, 2024. This is because the Korean age system considers everyone to age a year each New Year's Day, regardless of their actual birthday. Therefore, if asked in December of 2023, the answer would be that someone born in 2005 will be able to drink from January 1, 2024.
However, if the question is posed after January 1, 2024, the answer is definitively yes. Individuals born in 2005 are of legal drinking age under the Korean age system.