Pre-modern Koreans used a lunar calendar which meant that dates changed from year to year when determining holidays. These days however, Korea has embraced the solar calendar in accordance with the rest of the world. Yet much of the country still uses the lunar calendar to keep track of births and deaths and some traditional holidays. Many people celebrate their birthdays according to both calendars, and the first days of each calendar are national holidays.
All the following dates are national holidays for which you can expect to receive a day off work. As an English teach you will receive a total of 20 days of vacation throughout the whole year.