Lunar New Year's Day
Lunar New Year's Day is the one of the 2 biggest holidays in Korea(another one is Chuseok). Through these 2 biggest holidays, very many Korean people travel to visit families.
It's usually 3 days off(Lunar New Year's Day is in the middle and the former and the latter date is also off), so this year has Thursday, Friday and Saturday off, which are from February 15 to February 17.