• Publications of The Korean Astronomical Society
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• v.33 no.1
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• pp.1-7
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• 2018

In order to encourage collaboration with North Korea in astronomy research field, we have studied the astronomical almanacs published in South and North Korea. The almanac contains fundamental astronomical data including not only daily calendar data but also unique characteristics selected by necessity in each country. We compared the South and North Korean astronomical almanacs in terms of contents, detailed descriptions, unique items, and so forth. We used the 2017 almanac for South Korea and 1993 almanac which is useful for this research for North Korea. We found that there were several differences between South and North Korean almanacs. The North Korean almanac is published for the astronomer or navigator, thus it has supplementary information about spherical astronomy such as precession of the north pole and position of celestial bodies. Whereas the South Korean almanac is published for the general public, and it distinctively contains luni-solar calendar, 24 solar terms, national holidays, etc. This study could be helpful for research cooperation between South and North Korea in astronomy.

• Publications of The Korean Astronomical Society
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• v.26 no.1
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• pp.1-24
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• 2011

Korea Astronomy and Space Science Institute (KASI) has constructed online database of the Korean Astronomical Almanac as a part of the 'Knowledge and Information Business Project 2009' supported by the Ministry of Knowledge Economy. Throughout this project, KASI provides both digitized images and extracted text from the almanac covering approximately 240 years. The primary purpose of this paper is to serve as a reference for users of the almanac database. Hence, we introduce the calendar history and kinds of the astronomical almanac used in Korea, and explain the contents of the almanacs according to its appearance time. We also briefly mention the steps employed in constructing the database system and Web site. Since ancient times, astronomical almanacs have been an essential part of daily life. We, therefore, believe that the astronomical almanac database constructed by KASI will prove its usefulness in various fields, and particularly in the study of historical astronomy.

• Publications of The Korean Astronomical Society
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• v.9 no.1
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• pp.85-100
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• 1994

In Korea Astronomy Observatory, we developed a S/W package to compile the Korean Nautical Almanac. We describe the motivation to develop the S/W and explain the S/W package in general terms. In appendix, we describe the procedure to calculate the polaris table in more detail. When we developed the S/W, we paid much attention to produce accurate data. We also made great effort to automate the compilation of Nautical Almanac as far as possible, since the compilation is time consuming and labour extensive. As a result, the S/W we developed turns out to be very accurate and efficient to compile Nautical Almanac. In fact, we could compile a Korean Nautical Almanac in a few days.

• Publications of The Korean Astronomical Society
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• v.23 no.2
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• pp.53-63
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• 2008

Korea Astronomy and Space Science Institute (KASI), direct decendant of Korea National Astronomy Observatory, has been publishing Korean Astronomical Almanac since in 1976. The almanac contains essential data in our daily lives such as the times of sunrise, sunset, moonrise, and moonset, conversion tables between luni-solar and solar calendars, and so forth. So, we are planning to register Korean astronomical almanac data for national Standard Reference Data(SRD), which is a scientific/technical data whose the reliablity and the accuracy are authorized by scientific analysis and evalution. To be certificated as national SRD, reference data has to satisfy several criteria such as traceability, consistency, uncertainty, and so on. Based on similarity among calculation processes, we classified astronomical almanac data into three groups: Class I, II, and III. We are planning to register them for national SRD in consecutive order. In this study, we analyzed Class I data which is aimed to register in 2009, and presented the results. Firstly, we found that the traceability and the consistency can be ensured by the usage of NASA/JPL DE405 ephemeris and by the comparsion with international data, respectively. To evaluate uncertainty in Class I data, we solved the mathematical model and determined the factors influencing the calculations. As a result, we found that the atmospheric refraction is the main factor and leads to a variation of ${\pm}16$ seconds in the times of sunrise and sunset. We also briefly review the histories of astronomical almanac data and of standard reference data in Korea.

• Publications of The Korean Astronomical Society
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• v.30 no.3
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• pp.789-800
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• 2015

During the Joseon dynasty, the Gwansanggam (觀象監, The Royal Astronomical Observatory) was the royal administration in charge of Astronomy (天文), Geography (地理), Calendars (曆), Astronomical and meteorological observation (測候), and Timekeeping (刻漏). Of those affairs, the Astronomical Almanac compilation was most important. In this paper, we study the education and selection of astronomical officials in the 19th century during the Joseon dynasty, focusing on Astronomical Almanac officials. According to this study, their main area was calendar calculation, and they were involved in Astronomical Almanac compilation for nearly 40 years, until they resigned. In addition, they served as Samryeok-susulgwan (三曆修述官, Official for calendar calculation by the $Sh{\acute{i}}xi{\grave{a}}n$ calendar), and Ilgwa-gamingwan (日課監印官, Official printing supervisor). To undertake these core duties, an official had to pass several examinations and courses. The Gwansanggam (after Gwansangso) carried out the educational function for the officials. In particular, reserved officials of the astronomy division had to be educated starting with a trainee course.

• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.137-151
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• 1993

We have calculated the astronomical almanac 1994 and simulated the trajectory of a satellite orbit considering all perturbative forces with various initial conditions. In this work, Gauss Jackson multistep integration method has been used to calculate our basic equation of motion with high numerical accuracy. It has beer. found that our results agree well with the Astronomical Almanac Data distributed by JPL of NASA and the orbit simulations have been carried out with fast speed, stability and excellent round-off error accumulation, comparing with other numerical methods. In order to be carried out our works on almanac and orbit calculations easily by anyone who uses a personal computer, we have made a computer program on graphical user interface to provide various menus for detail works selected by a mouse.

• Publications of The Korean Astronomical Society
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• v.30 no.3
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• pp.801-810
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• 2015

The royal astronomical observatory compiled the Astronomical Almanac during the Joseon dynasty, though there were some changes of its organization. However, the observatory underwent sudden changes in the late period mainly due to the influence of historical events such as the Gabo (甲午) and The Eulmi (乙未) Reforms in 1894 and 1895, respectively, and the Japanese invasion in 1910. In this paper, we study the changes of the compilation institution of the Korean Astronomical Almanac and of its organization for the period of 1894 to 1912. During this period, the name of the observatory had been changed several times, from Gwansanggam (觀象監) to Gwansangguk (觀象局) in 1894 and to Gwansangso (觀象所) in 1895. In addition, the affair of the Astronomical Almanac compilation was transferred to the Editorial Bureau [編輯局] of the Ministry of Education [學部] and to the Editing Department [編輯課] of the Governor-General of Korea [朝鮮總督府]. In 1907, the Gwansangso was abolished. Moreover, the affair of timekeeping was separated and the official number of personnel was reduced to less than 5% compared to that of Gwansanggam. Consequently, the royal astronomical observatory was significantly reduced in terms of its functions and the organization through the process of those changes. Therefore, we believe that this period is important when seeking to understand the transition between the traditional Astronomical Almanac of the Joseon dynasty and its modern astronomical counterpart of the present day.

• Publications of The Korean Astronomical Society
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• v.35 no.1
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• pp.1-16
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• 2020

We report a calendar sheet for the 31st year of the reign of King Gojong (1894) (hereafter, calendar sheet 1894) in Korea, which calendrical data in a single page. This calendar sheet 1894 is composed of 14 rows by 14 columns (about 190 cells), and various calendrical data are recorded such as the sexagenary circle of the first day in each month, 24 solar terms, full moon day. In this paper, we compare calendrical data of 1894 calendar sheet with those of the almanac based on the Shixian calendar (hereafter, annual almanac) of the same year. Our findings are as follows. First, we find that the year is expressed using the reign-year of the king of the Joseon dynasty differently from using the reign-style of China in the annual almanac those times. Other calendar days of this calendar sheet are the same as those of the annual almanac in term of lunar dates, 24 solar terms, sexagenary days and so forth. Second, we find that the calendar sheet 1894 contains memorial days for 64 lineally ancestors of the Joseon royal family. These royal memorial days appears in the annual almanac two years later (i.e., 1896). Third, as the most distinctive feature, we find that the symbol of 工 kept every two cells. It was found that the cells can be filled with three days as the maximum number of days and then are labelled the same symbol 工 every second cell. This feature allows us to get the first year in which this kind of calendar sheet was published. It is conjectured one of 11 years, such as 1845, 1846, 1847, 1873, 1874, 1875, 1876, 1877, 1878, 1879 or 1880. We also think that the format of the calendar sheet 1894 has influenced on the Daehan-Minryeok (Korean civil calendar sheet) of 1920.

• Publications of The Korean Astronomical Society
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• v.22 no.4
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• pp.219-227
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• 2007

In this paper, we analyze the scientific inquiries type on Almanac and Historical Astronomy asked through the Q&A service in Korea Astronomy and Science Institute(KASI) webpage with the aid of scientific inquiries analysis methods. We also study the contents of the questions. Specifically, we have created statistics of questions and inquiries, and have developed categories to analyze the characteristics of questions with regard to their cognitive aspects. Each question is categorized as either of the two elements based on their recognitive aspect: science knowledge or science study. Each element also has sub-categories that help the reader understand the characteristics of the questions. For the analysis, we used the sample consisting of questions collected from April, 2005 to June, 2007. Through this study, we achieved a better understanding of the questions in the area of Almanac and Historical Astronomy asked in the Q&A service. Throughout this study, we find that the need of questions in the area of Almanac and Historical Astronomy are increasing with time, and the overall quality of the questions is getting improved. As we expect that the number of people using our Q&A service will increase and that the questions will get more difficult to answer, development of improved contents is required.

• Journal of the Korean Institute of Navigation
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• v.9 no.2
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• pp.1-12
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• 1985

In order to computerize the sight reduction process completely, the coordinates of celestial bodies have to be calculated. The author calculates the equtorial coordinates of the sun and stars using formulae by computer programming. And they are compared with data from an nautical almanac. Generally, data based on formulae is slightly less accurate than those derived from an nautical almanac. In the case of calculating coordinates of the sun, maximum error of GHA is $0{'\\.}2$, and that of declination is $0{'\\.}1$.