• 천문학논총
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• 제36권3호
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• pp.79-95
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• 2021

This study aims to develop a restoration model of an armillary sphere of Tongcheon-ui (Pan-celestial Armillary Sphere) by referring to the records of Damheonseo (Hong Dae-Yong Anthology) and the artifact of an armillary sphere in the Korean Christian Museum of Soongsil University. Between 1760 and 1762, Hong, Dae-Yong (1731-1783) built Tongcheon-ui, with Na, Kyung-Jeok (1690-1762) designing the basic structure and Ann, Cheo-In (1710-1787) completing the assembly. The model in this study is a spherical body with a diameter of 510 mm. Tongcheon-ui operates the armillary sphere by transmitting the rotational power from the lantern clock. The armillary sphere is constructed in the fashion of a two-layer sphere: the outer one is Yukhab-ui that is fixed; and the inner one, Samsin-ui, is rotated around the polar axis. In the equatorial ring possessed by Samsin-ui, an ecliptic ring and a lunar-path ring are successively fixed and are tilted by 23.5° and 28.5° over the equatorial ring, respectively. A solar miniature attached to a 365-toothed inner gear on the ecliptic ring reproduces the annual motion of the Sun. A lunar miniature installed on a 114-toothed inner gear of the lunar-path ring can also replay the moon's orbital motion and phase change. By the set of 'a ratchet gear, a shaft and a spur gear' installed in the solstice-colure double-ring, the inner gears in the ecliptic ring and lunar-path ring can be rotated in the opposite direction to the rotation of Samsin-ui and then the solar and lunar miniatures can simulate their revolution over the period of a year and a month, respectively. In order to indicate the change of the moon phases, 27 pins were arranged in a uniform circle around the lunar-path ring, and the 29-toothed wheel is fixed under the solar miniature. At the center of the armillary sphere, an earth plate representing a world map is fixed horizontally. Tongcheon-ui is the armillary sphere clock developed by Confucian scholars in the late Joseon Dynasty, and the technical level at which astronomical clocks could be produced at the time is of a high standard.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.133-140
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• 2020

Traction performance of a tractor varies depending on soil conditions. Sinkage and slip of the driving wheel for tractor frequently occur in a reclaimed land. The objective of this study was to develop a tractor suitable for a reclaimed land. Traction performance was evaluated according to soil conditions of reclaimed land and paddy field. Field experiments were conducted at two test sites (Fields A: paddy field; and Field B: reclaimed land). The tractor load measurement system was composed of an axle rotation speed sensor, a torque meter, a six-component load cell, GPS, and a DAQ (Data Acquisition System). Soil properties including soil texture, water content, cone index, and electrical conductivity (EC) were measured. Referring to previous researches, the tractor traveling speed was set to B3 (7.05 km/h), which was frequently used in ridge plow tillage. Soil moisture contents were 33.2% and 48.6% in fields A and B, respectively. Cone index was 2.1 times higher in field A than in field B. When working in the reclaimed land, slip ratios were about 10.5% and 33.1% for fields A and B, respectively. The engine load was used almost 100% of all tractors under the two field conditions. Traction powers were 31.9 kW and 24.2 kW for fields A and B, respectively. Tractive efficiencies were 83.3% and 54.4% for fields A and B, respectively. As soil moisture increased by 16.4%, the tractive efficiency was lowered by about 28.9%. Traction performance of tractor was significantly different according to soil conditions of fields A and B. Therefore, it is necessary to improve the traction performance of tractor for smooth operations in all soil conditions including a reclaimed land by reflecting data of this study.

• 한국도로학회논문집
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• 제20권1호
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• pp.107-115
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• 2018

PURPOSES : As the population of the mobility handicapped, who are classified as the disabled, the elderly, pregnant women, children, etc., has increased, the voices for guaranteeing their rights have been increasing as well. Thus, the design manuals for roads and sidewalks for the mobility handicapped were developed by the local government, such as the Ministry of Land, Transport, and Tourism, in Seoul City. However, according to the 2013 survey results of the Seoul Metropolitan City, the mobility handicapped still feel uncomfortable with the sidewalks, and particularly request for the improvement of the step and slope of the sidewalk curb. Therefore, in this study, we conducted an empirical experimental study to determine the slope of the sidewalk curb and height of the steps considering the mobility handicapped and analyzed whether there is a statistically significant difference. METHODS : The methodology of this study is an empirical experimental one. In the study, five non-disabled people, 10 wheelchair users, and 10 eye patch and stick users walked about 2-3 min on the sidewalk plates of the sloped type (0%, 5%, 6.3%, 8.3%) and stepped type (0 cm, 1 cm, 3 cm, 6 cm), and their human physiological responses, such as the skin temperature, volume of perspiration on forehead and chest, and heart rate, were measured and recorded. After combining the data, we conducted a nonparametric test, ANOVA, or t-test to determine whether there was a statistically significant difference according to each slope and step type. RESULTS : It was found that for the non-disabled, there was no significant difference in human physiological responses according to the slope and steps of the sidewalk. It can be said that the non-disabled do not feel much physiological discomfort while walking. In the case of the sloped sidewalk plate, the heart rate of the wheel chair users increased when the slope was 6.3%. In the case of the eye patch and stick users, the volume of perspiration on the chest increased at a slope of 5.0%. In general, it is judged that a sidewalk with a slope that is less than 5% does not cause a change in the physiological response. In the case of a stepped sidewalk plate, when 0 cm, 1 cm, and 3 cm were compared for wheelchair users, the amount of forehead perspiration increased from 1 cm. Meanwhile, in the case of the eye patch and stick users, when 0 cm and 6 cm were compared, the amount of perspiration on the forehead and chest as well as the heart rate all increased at 6 cm. Taken together, in the case of wheelchair users, a difference was shown when the height of the step of the sidewalk plate was 1 cm, suggesting that installing it at 0 cm does not cause any physiological discomfort. Moreover, in the case of the eye patch and stick users, when comparing only 0 cm and 6 cm, 0 cm was considered to be suitable, as there was a difference in physiological response at 6 cm. CONCLUSIONS : In this study, we set the human physiological responses such as chest skin temperature, amount of perspiration, and heart rate as evaluation items, and our study was considered to be a meaningful experiment that targeted wheelchair users as well as eye patch and stick users. The validity of the evaluation items was confirmed, as the results of human physiological responses were significant. As for the sidewalk design, according to the experiment result, it is considered that differential application should be implemented according to the type of mobility handicap, rather than uniformly applying a sidewalk step of 2 cm and sidewalk slope of 1/25, which are the current legal standards.

• 헤리티지:역사와 과학
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• 제36권
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• pp.5-38
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• 2003

The history of Baekje Kingdom, one of the Three kingdoms, is divided into three periods to the change of sociopolitical center, including its capital as follows: Hanseong Period (18 BC ~ AD 475), Ungjin Period (AD 475~538), and Sabi Period (AD 538~660). Though the Hanseong Period of Baekje Kingdom covers more than two thirds of the whole history of Baekje Kingdom (493 years), history and archaeological culture of the Hanseong Period is still unclear and even ambiguous comparing to the Ungjin and Sabi periods. Most of all, it is because of quite limited historical records and archaeological data available. In addition, negative attitude of the Korean academic circles to the early records of Samguksaki(三國史記) has been a critical obstacle to the study of early history of the Three kingdoms, including the Hanseong Period of Baekje kingdom. Author, who has attempted to combine historical records and archaeological data in order to reconstruct the history and archaeological culture of the early Baekje, specifically the Hanseong Period, has held positive attitude to the early records of the Samguksaki as far as possible. He(Author) came to realize that comprehensive understanding of Mahan (馬韓) society, one of the Three Han (三韓) Society was more than essential in the study of Baekje. According to historical records and archaeological data, Mahan Society represented by Mojiguk(目支國) ruled by King Jin(辰王) has been located in the middle and/or southwestern parts of the Korean peninsula from the 3rd~2nd century BC through the end of the 5th century or early 6th century AD. Mahan already occupied central portion of the Korean Peninsula, including the Han River Valley when King Onjo(溫祖王) first set up the capital of Baekje Kingdom at Wiryeseong (慰 禮城) considered to be modern Jungrang~Songpa-gu area of Han River Valley. From the beginning of the Baekje history, there had been quite close interrelationships between Baekje and Mahan, and the interrelationships had lasted for around 500 years. In other words, it is impossible to attempt to understand and study Hanseong period of Baekje, without considering the historical and archaeological identity of Mahan. According to the Samguksaki, Baekje moved its capital three times during the Hanseong Period (18 BC ~ AD 475) within the Han River Valley as follows: Wiryeseong at Jungrang-gu area of the Han River (河北慰禮城, 18 ~ 5 BC), Wiryeseong at Songpa-gu area of the Han River(河南慰禮城, 5 BC ~ AD 371), Hansan at Iseongsan fortress site(Historical site No. 422, 漢山, AD 371~391), and Hanseong at Chungung-dong of Hanam city(漢城, AD 391~475). Before 1990s, archaeological data of the Hanseong Period was quite limited, and archaeological culture of Mahan was not well defined. Only a few burial and fortress sites were reported to be archaeological remains of the early Baekje, and a few settlement and jar burial sites were assumed to be those of Mahan without clear definition of the Mahan Culture. Since 1990s, fortunately, a number of new archaeological sites of Hanseong Baekje and Mahan have been reported and investigated. Thanks to the new discoveries, there has been significant progress in the study of early Baekje and Mahan. In particular, a number of excavations of Pungnap-dong Fortress site(Historical site NO. 11, 1996~2003), considered to be the Wiryeseong at south of the Han River, the second capital of the Hanseong Baekje, provided critical archaeological evidence in the study of Hanseong Period of Baekje. Since the end of the 1990s, a number of sites have been reported in Gyeonggi, Chungcheong, and Jeolla provinces, as well. From these sites, archaeological features and artifacts representing distinctive cultural tradition of Mahan have been identified such as unstamped fortresses, pit houses cut into the rock, houses with lifted floor(掘立柱 건물), and potteries decorated with toothed wheel and bird's footprint designs. These cultural traditions reflected in the archaeological remains played a critical role to define and understand archaeological identity of the Mahan society. Moreover, archaeological data from these new sites reported in the middle and southwestern parts of the Korean Peninsular made it possible to postulate a hypothesis that the history of Mahan could be divided into three periods to the change of its sociopolitical center in relation with the Baekje Kingdom's political Situation as follows: Cheonan (天安) Period, Iksan(益山) Period, and Naju(羅州) Period. The change of Mahan's sociopolitical center is closely related to the sociopolitical expansion of the Hanseong Baekje.