한국 음력의 운용과 계산법 연구 (OPERATION OF A LUNISOLAR CALENDAR IN KOREA AND ITS CALCULATION METHOD)

We study the operation of a lunisolar calendar in Korea and its time data calculation method. Thedates based on the lunisolar calendar have been conventionally used in Korea after the Gregorian calendarwas introduced in 1896. With the Astronomy Act enacted in 2010, the lunisolar calendar is presently beingused as an official calendar along with the Gregorian calendar. However, no institutionalized regulationshave been provided on the time data calculation method by the lunisolar calendar. The Korea Astronomyand Space Science Institute very recently established the regulations on the lunisolar calendar operation inKorea. We introduce the regulations together with historical substances and analyze the time data calculatedaccording to the regulations for 600 years from 1901 to 2500. From our study, we find that the valueof ΔT (i.e., the difference between the terrestrial time and the universal time) is the most critical parametercausing uncertainty on the data. We also find that all new Moon days in the almanacs agree withour calculations since 1912. Meanwhile, we find that new Moon and winter solstice times are found to bevery close to midnight in 38 and five cases, respectively. For instance, the new Moon time on January 14,2097 is 0 h 0 min 8 s. In this case, deciding the first day (i.e., new moon day) in a lunar month is difficultbecause of the large uncertainty in the value of ΔT. Regarding with a lunar leap month, we findthat the rules of inserting the leap month do not apply for 17 years. In conclusion, we believe that ourfindings are helpful in determining calendar days by using the lunisolar calendar.

We study the operation of a lunisolar calendar in Korea and its time data calculation method. Thedates based on the lunisolar calendar have been conventionally used in Korea after the Gregorian calendarwas introduced in 1896. With the Astronomy Act enacted in 2010, the lunisolar calendar is presently beingused as an official calendar along with the Gregorian calendar. However, no institutionalized regulationshave been provided on the time data calculation method by the lunisolar calendar. The Korea Astronomyand Space Science Institute very recently established the regulations on the lunisolar calendar operation inKorea. We introduce the regulations together with historical substances and analyze the time data calculatedaccording to the regulations for 600 years from 1901 to 2500. From our study, we find that the valueof ΔT (i.e., the difference between the terrestrial time and the universal time) is the most critical parametercausing uncertainty on the data. We also find that all new Moon days in the almanacs agree withour calculations since 1912. Meanwhile, we find that new Moon and winter solstice times are found to bevery close to midnight in 38 and five cases, respectively. For instance, the new Moon time on January 14,2097 is 0 h 0 min 8 s. In this case, deciding the first day (i.e., new moon day) in a lunar month is difficultbecause of the large uncertainty in the value of ΔT. Regarding with a lunar leap month, we findthat the rules of inserting the leap month do not apply for 17 years. In conclusion, we believe that ourfindings are helpful in determining calendar days by using the lunisolar calendar.