Search

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 20th 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 Heumgyeonggaknu 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.

The present experiment was conducted to evaluate the efficacy of dietary fermented by-product of mushroom, Pleurotus ostreatus, (FBPM) as a fish meal (FM) replacer in juvenile Amur catfish, Silurus asotus. A total number of 225 fish averaging 5.7±0.1 g (mean±standard deviation) were fed one of the five experimental diets formulated to replace FM with FBPM at 0%, 5%, 10%, 20%, and 30% (FBPM0, FBPM5, FBPM10, FBPM20, and FBPM30, respectively). At the end of eight weeks of the experiment, average weight gain (WG) of fish fed FBPM0 or FBPM5 were significantly higher than those of fish fed FBPM20 or FBPM30 diets (p

The present experiment was conducted to evaluate the efficacy of dietary fermented by-product of mushroom, Pleurotus ostreatus, (FBPM) as a fish meal (FM) replacer in juvenile Amur catfish, Silurus asotus. A total number of 225 fish averaging 5.7±0.1 g (mean±standard deviation) were fed one of the five experimental diets formulated to replace FM with FBPM at 0%, 5%, 10%, 20%, and 30% (FBPM0, FBPM5, FBPM10, FBPM20, and FBPM30, respectively). At the end of eight weeks of the experiment, average weight gain (WG) of fish fed FBPM0 or FBPM5 were significantly higher than those of fish fed FBPM20 or FBPM30 diets (p<0.05). However, there was no significant differences in WG among the fish fed FBPM0, FBPM5 or FBPM10, and between fish fed FBPM10 or FBPM20, and also between those fed FBPM20 or FBPM30 diets. Lysozyme activity of fish fed FBPM0 or FBPM5 were significantly higher than those of fish fed FBPM10, FBPM20 or FBPM30 diets (p<0.05). The chemiluminescent response of fish fed FBPM5 was significantly higher than those of fish fed FBPM0, FBPM20 or FBPM30 diets (p<0.05). Broken line regression analysis of WG suggested that the maximal dietary inclusion level for FBPM as a FM replacer could be 6.3% without any adverse effects on whole body composition and on serological characteristics. Therefore, these results may indicate that the maximal dietary inclusion level of FBPM as a FM replacer could be 6.3% in juvenile Amur catfish. [ABSTRACT FROM AUTHOR]