• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.161-170
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• 2017

In this study, the characteristics of a horizontal sundial from the Joseon Dynasty were investigated. Korea's Treasure No. 840 (T840) is a Western-style horizontal sundial where hour-lines and solar-term-lines are engraved. The inscription of this sundial indicates that the latitude (altitude of the north celestial pole) is $37^{\circ}$ 39', but the gnomon is lost. In the present study, the latitude of the sundial and the length of the gnomon were estimated based only on the hour-lines and solar-term-lines of the horizontal sundial. When statistically calculated from the convergent point obtained by extending the hour-lines, the latitude of this sundial was $37^{\circ}$ $15^{\prime}{\pm}26^{\prime}$, which showed a 24' difference from the record of the inscription. When it was also assumed that a convergent point is changeable, the estimation of the sundial's latitude was found to be sensitive to the variation of this point. This study found that T840 used a vertical gnomon, that is, perpendicular to the horizontal plane, rather than an inclined triangular gnomon, and a horn-shaped mark like a vertical gnomon is cut on its surface. The length of the gnomon engraved on the artifact was 43.1 mm, and in the present study was statistically calculated as $43.7{\pm}0.7mm$. In addition, the position of the gnomon according to the original inscription and our calculation showed an error of 0.3 mm.

• Journal of Astronomy and Space Sciences
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• 제33권3호
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• pp.237-246
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• 2016

We analyze the design and specifications of the Sun-and-Stars Time-Determining group of instruments (Ilseong-jeongsi-ui, 日星定時儀) made during the Joseon dynasty. According to the records of the Sejong Sillok (Veritable Records of King Sejong), Sun-and-Stars Time-Determining Instruments measure the solar time of day and the sidereal time of night through three rings and an alidade. One such instrument, the Simplified Time-Determining Instrument (So-jeongsi-ui, 小定時儀), is made without the essential component for alignment with the celestial north pole. Among this group of instruments, only two bronze Hundred-Interval-Ring Sundials (Baekgak-hwan-Ilgu, 百刻環日晷) currently exist. A comparison of the functions of these two relics with two Time-Determining Instruments suggests that the Hundred-Interval-Ring Sundial is a Simplified Sundial (So-ilyeong, 小日影), as recorded in the Sejong Sillok and the Seongjong Sillok (Veritable Records of King Seongjong). Furthermore, the Simplified Sundial is a model derived from the Simplified Time-Determining Instrument. During the King Sejong reign, the Sun-and-Stars Time-Determining Instruments were used in military camps of the kingdom's frontiers, in royal ancestral rituals, and in royal astronomical observatories.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2012년도 제46차 하계학술발표논문집 20권2호
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• pp.303-304
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• 2012

본 눈문은 시각의 중요 수단으로 여겨지는 빛보다, 새로운 시각 표현 방법인 그림자에 초점을 맞추어 제작한 작품 에 대한 것으로 은 전통 시계인 해시계로부터 모티브를 얻었다. 이는 아두이노 보드(Arduino Board)와 SSR(Solid State Relay), 거리감지 센서, 220V 전구 등을 이용하여 제작했다. 이는 전구가 순차적으로 켜지면서 시계방향으로 그림자가 생기는 것을 작동 원리로 한다. 이 작품은 관객 참여를 바탕으로 하며 추후에 모바일 응용 분야로 발전될 가능성이 있다.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.395-401
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• 2015

We investigated the six remaining Yang-cheon-cheoks (量天尺), which were first described in the Veritable Record of King Sukjong (肅宗實錄). These woodblock sundials from Korea are structurally very similar to a Gyupyo (圭表, gnomon) or an altitude sundial and are light, compact, and portable. The front side of a Yang-cheon-cheok has two holes for styluses and several hour-lines. We compared the intervals of the hour-lines from the originating point of the stylus placement on all Yang-cheon-cheoks and found that two of the relics had the same hour-lines using the standard of the unit of 1 chon (寸). These two were actually the same sundial although the physical size was different. In spite of the lack of time accuracy, we hypothesize that various-sized Yang-cheon-cheoks were made and widely distributed throughout the public in the late Joseon Dynasty.

• Journal of Astronomy and Space Sciences
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• 제34권1호
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• pp.55-65
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• 2017

We studied the hour-lines of six extant Yangcheon-cheoks in Korea. To find whether Yangcheon-cheok was used in the whole area of Korea, we calculated the length of shadows of Yangcheon-cheok on the Korean Peninsula, Nanjing and Beijing as well as Hanyang (Seoul), according to 24 solar terms. Comparing the length of shadows with hour-lines of those relics, we could find that Yangcheon-cheok was suitable for use at limited times (from 9:00 to 15:00) during the year. Also, this sundial is more appropriate for use at low latitudes than high ones. Among existing relics, that of Seoul Museum of History made with porcelain was much more suitable to use at Hanyang and its higher latitude. Lee's collection was also suitable to use at Nanjing. It is certain that Yangcheon-cheok was a portable sundial which could be used from nine to fifteen of clock all the year around except for the winter season.

• 천문학회보
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• 제25권2호
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• pp.79-79
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• 2000

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.707-710
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• 1996

During King Sejong's reign in early Chosen Dynasty, the Korean science had been in full bloom. Among the many splendid achievements of the period, though most of them are not extant, astronomical instruments and clocks made for equipping the Royal Observatory are taken as typical works that reflect the characteristics of the King's scientific projects and discussed in the view point that what and how much a well-planned drive and a future-oriented leader can accomplish.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2000년도 한국우주과학회보 제9권2호
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• pp.79-79
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• 2000

No Abstract, See Full Text

• Journal of Astronomy and Space Sciences
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• 제32권1호
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• pp.73-80
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• 2015

The Yang-gyeong-gyu-il-ui (兩景揆日儀) is a kind of elevation sundial using three wooden plates. Sang-hyeok Lee (李尙爀, 1810~?) and Byeong-cheol Nam (南秉哲, 1817~1863) gave descriptions of this sundial and explained how to use it in their Gyu-il-go (揆日考) and Ui-gi-jip-seol (儀器輯說), respectively. According to Gyu-il-go (揆日考) there are two horizontal plates and two vertical plates that have lines of season and time. Subseasonal (節候) lines are engraved between seasonal (節氣) lines, subdividing the interval into three equal lines of Cho-hu (初候, early subseason), Jung-hu (中候, mid subseason) and Mal-hu (末候, late subseason); there are 13 seasonal lines for a year, thus resulting in 37 subseasonal lines; also, there are 12 double-hour (時辰) lines for a day engraved on these plates. The only remaining artifact of Yang-gyeong-gyu-il-ui was made in 1849 (the $15^{th}$ year of Heon-jong) and is kept at the Korea University Museum. We have compared and analyzed Yang-gyeong-gyu-il-ui and similar western sundials. Also, we have reviewed the scientific aspect of this artifact and built a replica. Yang-gyeong-gyu-il-ui is a new model enhanced from the miniaturization development in the early Joseon Dynasty and can be applied to the southern part of the tropic line through a structure change.

• 한국수학사학회지
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• 제25권4호
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• pp.83-99
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• 2012

고등학교 교육과정에서 학생들은 원뿔곡선 조작 환경을 제공 받지 못하고 초점과 준선을 이용하여 대수적 정의를 받아들이며, 원뿔곡선을 동적인 의미 없이 정적인 대수적 문제로 국한해서 생각하는 경향이 있다. 대수적인 표현뿐만 아니라 동적인 기하학적 표현을 보완하기 위해 원뿔곡선을 원뿔 절단으로 정의한 역사적 근거를 해시계에서 찾고 원뿔 절단으로는 설명할 수 없는 초점과 준선 개념의 역사도 살펴본다. 그리고 원뿔곡선을 연속적으로 그리기 위해 사용된 도구들에 대해서 알아보고, 학생들의 활동을 위한 공학적 도구로 컴퓨터 환경을 살펴본다.