This method always returns false, unless overridden by a derived class.
Leap years in the Korean calendar correspond to the same leap years in the Gregorian calendar. A leap year in the Gregorian calendar is defined as a Gregorian year that is evenly divisible by four, except if it is divisible by 100. However, Gregorian years that are divisible by 400 are leap years. A common year has 365 days and a leap year has 366 days.
A leap month is an entire month that occurs only in a leap year. The Korean calendar does not have any leap months.