King Sejong's Striking Clepsydra was an elaborate timekeeping and annunciating systems incorporating jackwork mechanisms capable of announcing hours, intervals and night-watches based on Shoushih calendrical system automatically. In this paper the author has studied the original manuscripts on the Striking Clepsydra [Sejong sillok, 65 : 1a-3b ff ; 16th year, 7th month(1434)] from a technical point of view undertaking a close analysis of this monumental clock and aiming at our modern understanding of the full degree of delicate mechanisms and sophisticated controls built into the twelve double-hours announcing jackwork. Based on the visible and audible signal model for marking the passage of hours, timekeeping, ball-rack, ball-relay, and audible and visible time-indicators mechanisms were synthesized reconstructing twelve double-hours time-annunciating systems. It revealed that the double-hour announcing processes were entirely operated by an open-and closed-loop fashion. Through this study the ball-operated timing signal and power-transmission mechanisms of the Striking Clepsydra has been analyzed. The time-annunciating jackwork allows us now to suggest more strongly that its ancestry may be traced through Yuan's Lantern Clepsydra in the Grand Illumination Hall, and 'Palace Clock' back to the milieu of al-Jazari's(1206) Arabic water-clocks. Surviving parts of the 1536 Striking Clepsydra as well as historical and philological data concerning the improvements of the proposed model were discussed.