Public holidays in South Korea are commonly known as 'Red Days' as this is how they are usually coloured in printed calendars.
The Korean government has announced that from the second half of 2014 onwards, if the date of Seollal, Chuseok, or Children's Day falls on Sunday, then the holiday will be extended to Monday.
Until the middle of 2014, Holidays are observed on their calendar date. If the date of a holiday falls on a Saturday or Sunday, then the holiday will not be moved to a weekday.