• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.493-504
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• 2004

동아시아의 역사서에는 일식에 대한 기록들이 다른 천문현상들에 비해 많이 나타난다. 이것은 전통적으로 일식은 왕조의 운명과 연관되어있다는 정치적인 사상 때문이다. 조선시대까지도 태양은 임금을 상징하였고, 일식이 일어나면 일식이 무사히 지나가도록 임금이 제사하는 구식례(求食禮)을 지내곤 했다. 따라서 당시의 임금은 일식에 대한 정확한 예보를 얻는 것이 상당히 중요한 일이었다. 그러나 그럼에도 불구하고 조선 초기의 일식 예측은 잘 맞지가 않았다. 이에 세종은 당시 수도인 한양의 위치에 맞는 역법서(曆法書)인 칠정산내편과 칠정산외편을 편찬하였고, 이로 인해 비로소 조선의 자주적인 역법(曆法)이 확립되었다. 칠정산외편은 아라비아의 역법인 회회력(回回曆)을 기초로 해서 만들어진 역법으로 조선 초기의 일식 계산에서는 당시의 여러 역법 계산 결과보다 더 정확하였고, 현대적인 계산 방법과 비교하여 보아도 오차의 범위내에 잘 들어맞음을 알 수 있었다.

• Journal of Astronomy and Space Sciences
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• 제27권1호
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• pp.55-68
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• 2010

It has been generally known that Datong-li (a Chinese calendar in the Ming dynasty) was first introduced into Korea in the nineteenth reign of King Gongmin (1370) of the Goryeo dynasty and lasted to the third reign of King Hyeojong (1652) of the Joseon dynasty. This understanding is based on the records of Goryeo-sa (History of the Goryeo dynasty) and of Seoungwan-ji (Official book of Seoungwan)/Jeungbomunheon-bigo (Explanatory Notes of Library Document). To verify the period of the use of Datong-li in Korea, we develop a Fortran code to calculate the calendar day by Datong-li and also investigate historical literatures and extant almanacs. As a result, we find the possibility that Datong-li had been in use since 1389 at least. However, we cannot confirm whether Datong-li was first enforced in 1370 or not. On the other hand, we confirm that Datong-li was used until 1653 and reintroduced during the period from 1667 to 1669. Also, we find that previous studies had some errors in the sexagenary cycle of the real first day of a month. We think that this study will contribute to understanding the calendrical history of the Joseon dynasty.

• 천문학논총
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• 제33권2호
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• pp.9-19
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• 2018

We investigate the life of Lee Cheon (1376-1451) who was closely connected with astronomy during the reign of King Sejong of the Joseon dynasty. Lee Cheon is widely regarded as one of the outstanding scientists of King Sejong's period. However, his contributions to the development of the astronomy during the period have not been enlightened. Based on the historical records on the life and achievements of Lee Cheon, mainly referring to the Joseonwangjosillok (Annals of the Joseon Dynasty), we address three important points. First, Lee Cheon was a distinguished administrator who filled various government posts. Second, he was a supervising engineer in public works and metal smelting during his position in military. Third, he was a scientific technician and manufactured precision equipment such as the metal movable type sets. By virtue of these aspects, Lee Cheon was taken into confidence by King Sejong on the Ganui-dae project (i.e., manufacture various astronomical instruments and construct their platform in order to make a calendar suitable for Joseon). During the period of this project, Lee Cheon not only supervised the construction of the Ganui (simplified armillary sphere) and Ganui-dae (platform for astronomical instruments) but also participated in the production of the astronomical instruments such as Gyupyo (Gnomon) and Honcheonui (Armillary Sphere). In conclusion, we regard Lee Cheon as one of the astronomers who led a great advance in astronomy during King Sejong's era.

• 천문학회지
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• 제48권6호
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• pp.325-331
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• 2015

We study an association between the duration of solar activity and characteristics of the latitude distribution of sunspots by means of center-of-latitude (COL) of sunspots observed during the period from 1878 to 2008 spanning solar cycles 12 to 23. We first calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month to determine the latitudinal distribution of COL of sunspots appearing in the long and short cycles separately. The data set for the long solar cycles consists of the solar cycles 12, 13, 14, 20, and 23. The short solar cycles include the solar cycles 15, 16, 17, 18, 19, 21, and 22. We then fit a double Gaussian function to compare properties of the latitudinal distribution resulting from the two data sets. Our main findings are as follows: (1) The main component of the double Gaussian function does not show any significant change in the central position and in the full-width-at-half-maximum (FWHM), except in the amplitude. They are all centered at ~ 11° with FWHM of ~ 5°. (2) The secondary component of the double Gaussian function at higher latitudes seems to differ in that even though their width remains fixed at ~ 4°, their central position peaks at ~ 22.1° for the short cycles and at ~ 20.7° for the long cycles with quite small errors. (3) No significant correlation could be established between the duration of an individual cycle and the parameters of the double Gaussian. Finally, we conclude by briefly discussing the implications of these findings on the issue of the cycle 4 concerning a lost cycle.

• 천문학회보
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• 제37권2호
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• pp.102.1-102.1
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• 2012

In this paper, we analyzed Korean historical records of the periodic comet Halley in three periods (Three Kingdoms, the Goryeo dynasty, and the Joseon dynasty) using various sources such as Samguksagi (History of the Three Kingdoms), Goryeosa (History of the Goryeo Dynasty), and Joseonwangjosillok (Annals of the Joseon Dynasty). To determine the apparition time of the comet at each return, we referred to the works of Kronk. For the Three Kingdoms period, we could not find any record relevant to Halley's comet from Samguksagi. Instead, we examined the suggestion that the phenomenon two Suns appearing on April 1, 760 (in a luni-solar calendar), which is recorded in Samgukyusa (Renaissance of the Three Kingdoms), indicates an appearance of comet Halley during the daytime. In contrast, we found that all the returns of Halley's comet during the Goryeo dynasty are recorded, although some accounts are questioned. In addition, we found that the appearance of Halley's comet in 1145 is also mentioned in a spirit-path stele made in 1178. For the Joseon dynasty period, we found that all the returns of the comet are recorded, as with the Goryeo dynasty, except for the return of 1910, in which the former dynasty fell. In conclusion, we think that this study will be helpful for understanding Korean historical accounts of Halley's comet.

• 천문학회보
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• 제44권2호
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• pp.62.1-62.1
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• 2019

우리는 한 장으로 된 조선 후기 달력을 발견하였다. '성상 31년(즉 고종 31년, 1894)-광서 20년'의 제목을 가지고 있는 이 달력은 1년간 역일의 내용을 방안 형태의 표에 작성하고 있어 '고종 31년(1894) 연력장' 이라고 부를 수 있다. 조선은 태음태양력인 대통력과 시헌력을 왕실의 행정기관에서 발간하였다. 이러한 책력은 2년 전에 월력장을 제작하여 진상하는 사례가 있었지만, 연력장처럼 한 해의 역일이 모두 있는 사례는 보고되지 않았다. 조선은 책력을 사적으로 편찬하는 것을 엄금하였기 때문에, 관상감서인(署印)이 없는 연력장이 유통될 수 있는 법적 근거가 없는 상황이었다. 우리는 고종 31년(1894) 연력장을 '대청광서이십년세차갑오시헌서(大淸光緖二十年歲次甲午時憲書, 1894)'와 비교하였다. 연력장의 역일은 12 x 12의 방안에 기록되어 있고 역일 영역의 상부, 좌부, 우부에 역주 관련 요소가 기록되어 있다. 연력장의 역일 중 특정일을 표시할 때는 역일의 숫자 대신 특정일을 상징어로 표시하고 있다. 이에 따르면 일진, 망, 24기, 잡절(한식, 삼복(三伏), 이사(二社), 토왕용사, 납일) 등을 알 수 있다. 이러한 특정일 및 역주 관련 요소가 1894년 시헌서와 잘 일치함을 확인하였다. 특기할 사항은 역일 영역 상부에 고종과 그 가족의 탄일(誕日)이, 역일 부분에 국기일(國忌日)이 기록되어 있다. 왕실의 국기일 및 탄일은 1896년 이후에 발간된 책력부터 기록된 점과 비교될 수 있다. 이러한 점으로 미루어 보아, 우리는 고종 31년(1894) 연력장이 민간보다는 왕실 혹은 지방 관아에서 사용되었을 것으로 추정하였다.

• 한국수학사학회지
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• 제28권2호
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• pp.73-83
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• 2015

In this paper, we give answers to some interesting questions about a Confucian scholar and mathematician in the late Joseon Dynasty, CHOI Seok-Jeong(崔錫鼎, 1646-1715), who was inducted into the Science and Technology Hall of Fame (http://kast.or.kr/HALL) for his mathematical achievements in October, 2013. In particular, we discover that CHOI Seok-Jeong was able to devote his natural abilities and time to do research on mathematics, and that he frequently communicated with his friend and fellow scholar, LEE Se-Gu(李世龜, 1646-1700), who was an expert on the astronomical calendar and mathematics, based on at least 24 letters between the two.

• 한국수학사학회지
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• 제34권5호
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• pp.165-191
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• 2021

The simple simultaneous linear congruence equation solution in 《Sunzi Suanjing孫子算經》 has developed into a systematic general solution in 《Shuxue Jiuzhang數書九章》. The most important parts of it is the creation of the Dayan Qiuyishu大衍求一術. The reason why 《Sanhak Jeongeui算學正義》 deals with the Dayanshu大衍術 which has lost its practicality in the calculation of astronomical calendar, is that one of the best achievement of traditional mathematics cannot be omitted. It is written with an emphasis on the disclosure of the calculation principle. It shows that Nam Byeong-gil南秉吉 and Lee Sang-hyeok李尙爀 had a fairly structural understanding of the Dayan Qiuyishu.

• 천문학회지
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• 제49권4호
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• pp.163-173
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• 2016

In this paper, we study the lunar eclipse records in the Goryeosa (History of the Goryeo Dynasty), an official history book of the Goryeo dynasty (A.D. 918 - 1392). In the history book, a total of 228 lunar eclipse accounts are recorded, covering the period from 1009 to 1392. However, we find that two accounts are duplications and four accounts correspond to no known lunar eclipses around the dates. For the remaining lunar eclipses, we calculate the magnitude and the time of the eclipse at different phases using the DE406 ephemeris. Of the 222 lunar eclipse accounts, we find that the minimum penumbral magnitude was 0.5583. For eclipses which occurred after midnight, we find that some accounts were recorded on the day before the eclipse, like the astronomical records of the Joseonwangjosillok (Annals of the Joseon Dynasty), while others were on the day of the lunar eclipse. We also find that four accounts show a difference in the Julian dates between this study and that of Ahn et al., even though it is assumed that the Goryeo court did not change the dates in the accounts for lunar eclipses that occurred after midnight. With regard to the contents of the lunar eclipse accounts, we confirm that the accounts recorded as total eclipses are accurate, except for two accounts. However, both eclipses were very close to the total eclipse. We also confirm that all predicted lunar eclipses did occur, although one eclipse happened two days after the predicted date. In conclusion, we believe that this study is very helpful for investigating the lunar eclipse accounts of other periods in Korea, and furthermore, useful for verifying the calendar dates of the Goryeo dynasty.

• 천문학논총
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• 제29권1호
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• pp.1-16
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• 2014

Sambok (三伏, Three Hottest Days) is the common designation of Chobok (初伏, Early Hot Day), Jungbok (中伏, Middle Hot Day), and Malbok (末伏, Late Hot Day), and widely known to be one of the Korean folk customs. Hence, Sambok is notated in Manseryeok (Ten Thousand-Year Almanac) and in the annual astronomical almanac published by Korea Astronomy and Space Science Institute. In this paper, we investigate the changes of Sambok in Korea based on various documents such as Joseonwangjosilok (朝鮮王朝實錄, Annals of the Joseon Dynasty), Jeungbo-Jakryeoksik (增補作曆式, The Supplement of Manual for Calendar Making), astronomical almanacs, and so forth. According to Jeungbo-Jakryeoksik preserved in Kyujanggak Institute for Korean Studies, Chobok and Jungbok are defined as the third and fourth Gyeongil (庚日, The Day Starting with the Seventh Heavenly Stems in Sexagenary Cycles Assigned to Each Day) after the summer solstice, respectively, and Malbok is the first Gyeongil after Ipchu (Enthronement of Autumn). However, if the summer solstice is Gyeongil, then the third Gyeongil counting from the solstice becomes Chobok. Malbok depends on the time of Ipchu. Ipchu itself becomes Malbok if the time of Ipchu is in the morning, or next Gyeongil becomes Malbok if it is the afternoon. On the other hand, Malbok is defined as Ipchu itself regardless of its time according to Chiljeongbobeob (七政步法, Calculating Method for Sun, Moon, and Five Planets), Chubocheobryeo (推步捷例, Quick Examples for Calendrical Calculations), and so on. To verify the methods used to determine Sambok, we examined the record in the extant almanacs during the period of 1392 to 2100 for which the summer solstice or Ipchu is Gyeongil. As a result, we found a periodicity that if the time of Ipchu is in the morning, in general, the time is in the afternoon after two years and then is back into in the morning after nineteen years, i.e., the 2 + 19 years periodicity. However, we found the 2 + 17 years periodicity in some years. We also found that the Chobok method of Jeungbo-Jakryeoksik has been used since 1712, the thirty-eighth reign of King Sukjong (肅宗). In addition, we supposed that Malbok had been determined by the method like Chubocheobryeo since either 1846, the twelfth reign of King Heonjong (憲宗), or 1867, the fourth reign of King Gojong (高宗). At present, these methods of Sambok are customarily used without any legal basis. We, therefore, think that this study will help conventionalize the method defining Sambok in the future.