• Publications of The Korean Astronomical Society
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• v.37 no.3
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• pp.35-47
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• 2022

This study investigated the stone Angbu-ilgu (scaphe sundial) of the Korea Meteorological Administration (KMA) and the Seoul Museum of History (SMH). Since the first Angbu-ilgu was produced in Korea in 1434 (the year of the reign of King Sejong), Angbu-ilgu has been reproduced with various materials. The upper surface of these two stone Angbu-ilgus symbolizes the horizon. On the hemisphere concave at the center of the horizon, the South Pole, the time line, and the season line are engraved. On the horizon of both the KMA and SMH Angbu-ilgus, the schematic, typeface, and composition of the inscription completely coincide with each other. In this study, it was estimated that the appearance of the KMA Angbu-ilgu, which was damaged at some point previously at least once, was similar to that of the SMH Angbu-ilgu, and this means that it is superficially similar with Treasure No 840, the stone horizontal sundial. In the concave hemisphere of both the stone Angbu-ilgus of the KMA and SMH, there are hour lines and 24 solar-term lines (13 line), and there is an intersection point where these lines meet the horizon, respectively. It can be verified that these intersections of these two Angbu-ilgus can be calculated as having a latitude of +37°39'15". The hour lines of the two stone Angbu-ilgus show that they were made after about 1900.

• Journal of Astronomy and Space Sciences
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• v.28 no.2
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• pp.143-153
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• 2011

The sundials produced in King Sejong era had the functions of accurate observation instruments and were fabricated in various forms such as Angbuilgu (hemispherical sundial). In this study, we investigated the literature, structural characteristics and principles of Hyeonjuilgu, Cheonpyeongilgu and Jeongnamilgu that were developed in Joseon to have the unique structures. Additionally, the sundials were reviewed in the perspective of technical history by comparing them with the sundials of China. For the restoration of the sundials, we identified the principle in which the light spots and shade of the sun were used, and drew the variations of the altitude and azimuth by the yearly motion of the sun on the Siban on the hemispheric and flat surfaces. Based on these results, we completed the design drawings of the three sundials and proposed the restoration models.

• School Mathematics
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• v.15 no.1
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• pp.159-177
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• 2013

This study is a case study of STEAM education. We have developed teaching and learning materials, suggested teaching method, and analysed the result for exploring the potential and effect of STEAM. The content of this study is based on the history of mathematics. Science (S) is related to the 24 divisions of the year, the height of the sun, the movement of heavenly bodies. Technology (T) is related to the exploration with graphic calculators. Engineering (E) is related to design sundial and research on the design principles. Art (A) is related to literature review about mathematical history, the understanding of the value of the mathematics. Mathematics (M) is related to the trigonometric functions. We have considered that Project-Based Learning is proper teaching and learning for STEAM education, we have designed the STEAM PBL and analysed the results focused on the developing integrative knowledge, mathematical attitude including mathematical value, the competencies of 21 century. The result of this study is as follows. We find that STEAM education activates students' collaboration, communication skills and improves representation and critical thinking skills. Also STEAM education makes positive changes of students' mathematical attitudes including the values of the mathematics.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.161-172
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• 2010

In this paper, we investigate the sundials made by the Kang Family of Jinju in the later period of the Joseon dynasty in terms of their characteristics, functions and the manufacturing technique. One of the characteristics of these sundials is that the value of polar height (i.e., the latitude of Seoul), the name of manufacturer, 24 seasonal subdivisions and so forth are written on the surface. In particular, polar height is expressed as '$37^{\circ}$ 39' 15"' in all 12 sundials examined in this study. To investigate the manufacturing technology in terms of astronomy, we analyze the positions of gnomon and of the lines corresponding to 24 seasonal subdivisions (season lines) and to each hour (hour lines). To verify the accuracy of the positions, we use a planar projection method. That is, we obtain 2D images of the sundials using a camera or scanner, and compare these with astronomical calculations for the positions of gnomon and season/hour lines. We believe that this method will be very useful for the study of sundials preserved elsewhere.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.48.2-48.2
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• 2017

우리는 문화재청에서 제공한 보물 840호의 3D 스캔 자료를 이용하여 이 해시계의 위도와, 영침의 길이와 형태, 그 위치에 대해 분석하였다. 국립고궁박물관에는 조선후기 돌널판에 제작된 지평일구가 남아있다. 보물로 지정된 두 유물 중 840호에 새겨진 신법지평일구라는 명문에 의거하여 이 해시계 명칭이 사용되었다. 서양의 구면천문학을 적용하여 제작된 이 지평일구는 단지 시각선과 절기선이 새겨져 있고, 그 밖에 핀 모양의 홈과 깊은 구멍 하나가 흔적으로 남아 있다. 우리는 지평일구의 시각선이 수렴하는 점을 직교좌표의 원점으로 삼았다. 3D 스캔 자료에서 시각선의 연장선은 한 점이 아닌 원점 근처에서 수 mm 이내에서 분산되었다. 각 시각선마다의 원점을 설정하여 계산한 해시계의 위도는 평균 $37^{\circ}\;15^{\prime}{\pm}26^{\prime}$을 보였고, 이는 보물 840호 명문의 37도 39분과 24'의 차이를 나타내었다. 우리의 분석에 따르면 시반의 구멍은 영표가 서있는 위치였으며, 영표의 길이는 $43.7{\pm}0.7mm$로 핀 모양 홈의 길이인 43.1 mm에 근접하였다. 이를 통해 이지평일구는 북극을 지시하는 삼각영표가 아닌 수직의 핀 모양의 영침이 설치된 것을 확인할 수 있었다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.96.1-96.1
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• 2012

Science we have perceived as genuine science is based on western scientific enterprise, that is, western modern science(WMS). The K-12 science curriculum in Korea absolutely contains WMS content. Elkana(1981) criticized the indifference of comparative science in the field of science, whereas there have been a lot of comparative studies of art, religion, ethics, and politics. Science is the product not only based on 'western' culture but all cultural around the world including Korea. People have consistently observed and tested for such a long period of time all over the world. Traditional science of Korea can be related to multiculturalism, which has become important in many fields. Korea has a lot of great scientific enterprises, such as astronomical instruments of Chosun Dynasty and ancient data of natural phenomenon in Samguk-saki or Samguk-Yusa. It is expected that students will consider them as more 'objective' and 'realistic' things rather than 'artistic' and 'distinguished' things. Astronomy was also very important in the East because they believed sky as king, which results in the development of a lot of astronomical data and instruments in Korean history. In this study, we developed three units of science programs using astronomical enterprises in Korea: 1) Activities with our sundial, Angbuilgu:, 2) data interpretation of natural phenomenon in ancient Korea, 3) experience in Gyeongbokgung Palace. From these programs, we expect that students will develop a profound understanding and take pride in our science.

• Publications of The Korean Astronomical Society
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• v.38 no.3
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• pp.147-160
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• 2023

In this study, we explore and catalog Korean astronomical heritages that are known to be preserved in foreign countries. We exclude old astronomical books from the catalog because they have been well studied and exist in numbers far too large for the scope of this study. From various documents and online collections, we find a total of 38 Korean astronomical heritages in six countries: 10, 11, and 14 items from the UK, France, and Japan, respectively, and 1 item from Germany, the US, and China each. These include items that are suspected to be of Chinese heritage and items of unconfirmed possession status. We divide the astronomical heritages primarily into two groups: time-keeping instruments (18 items) and astronomical charts (20 items). In this paper, we briefly review them according to country. We believe that this study provides a foundation for further detailed studies on each item, such as the Gujang-Cheonsang-Yeolcha-Bunya-Jido (舊藏天象列次分野之圖) preserved in the Library of Congress, United States.

• Journal of Astronomy and Space Sciences
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• v.34 no.1
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• pp.45-54
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• 2017

This study examines the scale unique instruments used for astronomical observation during the Joseon dynasty. The Small Simplified Armillary Sphere (小簡儀, So-ganui) and the Sun-and-Stars Time-Determining Instrument (日星定時儀, Ilseong-jeongsi-ui) are minimized astronomical instruments, which can be characterized, respectively, as an observational instrument and a clock, and were influenced by the Simplified Armilla (簡儀, Jianyi) of the Yuan dynasty. These two instruments were equipped with several rings, and the rings of one were similar both in size and in scale to those of the other. Using the classic method of drawing the scale on the circumference of a ring, we analyze the scales of the Small Simplified Armillary Sphere and the Sun-and-Stars Time-Determining Instrument. Like the scale feature of the Simplified Armilla, we find that these two instruments selected the specific circumference which can be drawn by two kinds of scales. If Joseon's astronomical instruments is applied by the dual scale drawing on one circumference, we suggest that 3.14 was used as the ratio of the circumference of circle, not 3 like China, when the ring's size was calculated in that time. From the size of Hundred-interval disk of the extant Simplified Sundial in Korea, we make a conclusion that the three rings' diameter of the Sun-and-Stars Time-Determining Instrument described in the Sejiong Sillok (世宗實錄, Veritable Records of the King Sejong) refers to that of the middle circle of every ring, not the outer circle. As analyzing the degree of 28 lunar lodges (lunar mansions) in the equator written by Chiljeongsan-naepyeon (七政算內篇, the Inner Volume of Calculation of the Motions of the Seven Celestial Determinants), we also obtain the result that the scale of the Celestial-circumference-degree in the Small Simplified Armillary Sphere was made with a scale error about 0.1 du in root mean square (RMS).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.411-418
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• 2004

This paper is the study about a method for determining the azimuth of a baseline by measuring the apparent direction of the Sun. It is simple to realize this method, as it requires, in addition to the apparent direction of the Sun already measured, the observation time and the latitude and the longitude of the survey point. Comparing the azimuths determined by this method and those determined by the PDGPS(Post Processed Differential GPS) on 3 different baselines, the differences(PDGPS - this method) between the azimuths determined by two methods were -13", +45" and +24" respectively. It can be an effective and rapid tool in cases that require the accuracy lower than 1 arc-min.than 1 arc-min.

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.63-71
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• 2015

During the reign of King Sejong (世宗, 1418-1450) in the Joseon Dynasty, there were lots of astronomical instruments, including miniaturized ones. Those instruments utilized the technical know-how acquired through building contemporary astronomical instruments previously developed in the Song(宋), Jin(金), and Yuan(元) dynasties of China. In those days, many astronomical instruments had circles, rings, and spheres carved with a scale of 365.25, 100, and 24 parts, respectively, on their circumference. These were called the celestial-circumference degree, hundred-interval (Baekgak), and 24 direction, respectively. These scales are marked by the angular distance, not by the angle. Therefore, these circles, rings, and spheres had to be optimized in size to accomodate proper scales. Assuming that the scale system is composed of integer multiples of unit length, we studied the sizes of circles by referring to old articles and investigating existing artifacts. We discovered that the star chart of Cheonsang yeolcha bunyajido was drawn with a royal standard ruler (周尺) based on the unit length of 207 mm. Interestingly, its circumference was marked by the unit scale of 3 puns per 1 du (or degree) like Honsang (a celestial globe). We also found that Hyeonju ilgu (a equatorial sundial) has a Baekgak disk on a scale of 1 pun per 1 gak (that is an interval of time similar to a quarter). This study contributes to the analysis of specifications of numerous circular elements from old Korean astronomical instruments.