• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.481-488
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• 2009

The purpose of this study was to investigate the hokey scoop motion of elite male hockey players. To accomplish the goal of this study, eight male hockey players participated and were divided into two groups (superior group Vs. inferior group). To find differences between groups, a three-dimensional motion analysis was performed with seven infrared cameras (SF: 200Hz). After analyzed their scoop motion, followings were found. 1) The non-significant(p>.05) increase in anterior CG displacement and velocities were found in superior group compare with inferior group) 2) There were no significance found in anterior-posterior stick velocities between groups. However, significant (p<.05) increase in vertical stick velocities were found in superior group than inferior group indicating the superior group has more skilled in scooping. 3) The significant(p<.05) increase in adductional and internal rotational stick released velocities were found in superior group than inferior group.

• Journal of Astronomy and Space Sciences
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• v.34 no.2
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• pp.171-182
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• 2017

In this study, the internal structure of a Heumgyeonggak-nu (欽敬閣漏) was designed, and the power transmission mechanism was analyzed. Heumgyeonggak-nu is an automated water clock from the Joseon Dynasty that was installed within Heumgyeonggak (欽敬閣), and it was manufactured in the $20^{th}$ year of the reign of King Sejong (1438). As descriptions of Heumgyeonggak-nu in ancient literature have mostly focused on its external shape, the study of its internal mechanism has been difficult. A detailed analysis of the literature record on Heumgyeonggak-nu (e.g., The Annals of the Joseon Dynasty) indicates that Heumgyeonggak-nu had a three-stage water clock, included a waterfall or tilting vessel (欹器) using the overflowed water, and displayed the time using a ball. In this study, the Cheonhyeong apparatus, water wheel, scoop, and various mechanism wheels were designed so that 16 fixed-type scoops could operate at a constant speed for the water wheel with a diameter of 100 cm. As the scoop can contain 1.25 l of water and the water wheel rotates 61 times a day, a total of 1,220 l of water is required. Also, the power gear wheel was designed as a 366-tooth gear, which supported the operation of the time signal gear wheel. To implement the movement of stars on the celestial sphere, the rotation ratio of the celestial gear wheel to the diurnal motion gear ring was set to 366:365. In addition, to operate the sun movement apparatus on the ecliptic, a gear device was installed on the South Pole axis. It is expected that the results of this study can be used for the manufacture and restoration of the operation model of Heumgyeonggak-nu.