Why are many businesses closed on Mondays?

In the years following the end of the Korean War, Koreans worked 7 days a week to bring their economy back to life. As the Korean economy grew, Friday, Saturday, and Sunday afternoons were heavy shopping days. Once the work week began again, sales traditionally decreased on Monday. For this reason, much the same as in many other countries, Korean shops, museums, galleries and restaurants are often closed on Monday.