• Journal of Astronomy and Space Sciences
• /
• v.34 no.1
• /
• pp.45-54
• /
• 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 Astronomy and Space Sciences
• /
• v.33 no.3
• /
• pp.237-246
• /
• 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.

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.39.2-39.2
• /
• 2013

We use grid-based hydrodynamic simulations to study star formation history in nuclear rings of barred-spiral galaxies. In our previous study, we concentrated on bar-only galaxies without spirals, finding that the star formation rate (SFR) in a nuclear ring exhibits a strong primary burst at early time before decreasing to below 1 $M_{\odot}/yr$ at late time. The rapid decline is caused by the paucity of the gas in the bar region, due to early massive gas inflows to the nuclear ring. Since star formation in nuclear rings is observed to be sustained for about 1-2 Gyr, this requires mechanisms to supply the gas to the bar regions. In this work, we study the effect of spiral arms on the radial gas inflows and related star formation in the nuclear rings. We show that spiral arms are efficient to remove angular momentum of the gas to cause significant gas inflows to the bar region, provided the patten speed of the arms is much smaller than that of the bar. The inflowing gas is added to a nuclear ring, making the ring SFR episodic over a long period of time. The time interval of multiple bursts of star formation is a few tens to hundred million years, with the mean peak SFR of ${\sim}5M_{\odot}/yr$, consistent with observations of M100.

• Journal of Astronomy and Space Sciences
• /
• v.19 no.3
• /
• pp.231-242
• /
• 2002

So-ganui, namely small simplified armillary sphere, was invented as an astronomical instrument by Lee Cheon, Jeong Cho, Jung In-Ji under 16 years’ rule of King Sejong. We collect records and observed data on So-ganui. It is designed to measure position of celestial sphere and to determine time. It also can be transformed equatorial to horizontal, and horizontal to equatorial coordinate. It can measure the right ascension, declination, altitude and azimuth. It is composed of Sayu-hwan (Four displacements), Jeokdo-hwan (Equato.ial dial), Baekgak-hwan (Ring with one hundred-interval quarters), Gyuhyeong (Sighting aliadade), Yongju (Dragon-pillar) and Bu (Stand). So-ganui was used conveniently portable surveying as well as astronomical instrument and possible to determine time during day and night.

• Safety and Health at Work
• /
• v.8 no.2
• /
• pp.162-168
• /
• 2017

Background: Pelvic ring fractures (PRFs) may influence the daily activities and quality of life of the injured. The aim of this retrospective study was to explore the functional outcomes and factors related to return to work (RTW) after PRF. Methods: During the years 2003-2012, 282 injured individuals aged 20-55 years on the date of the accident, were hospitalized and treated for PRFs in a large tertiary hospital in Athens, Greece. One hundred and three patients were traced and contacted; 77 who were on paid employment prior to the accident gave their informed consent to participate in the survey, which was conducted in early 2015 through telephone interviews. The questionnaire included variables related to injury, treatment and activities, and the Majeed pelvic score. Univariate and multiple regression analyses were used for statistical assessment. Results: Almost half of the injured (46.7%) fully RTW, and earning losses were reported to be 35% after PRF. The univariate analysis confirmed that RTW was significantly related to accident site (labor or not), the magnitude of the accident's force, concomitant injuries, duration of hospitalization, time to RTW, engagement to the same sport, Majeed score, and complications such as limp and pain as well as urologic and sexual complaints (p < 0.05 for all). On multiple logistic regression analysis, the accident sustained out of work (odds ratio: 6.472, 95% confidence interval: 1.626-25.769) and Majeed score (odds ratio: 3.749, 95% confidence interval: 2.092-6.720) were identified as independent predictive factors of full RTW. Conclusion: PRFs have severe socioeconomic consequences. Possible predictors of RTW should be taken into account for health management and policies.

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