• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.702-706
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• 1996

The King Sejong's Striking water-clock was named for its distictive day and night time announcing system. Its time announcing system generates acoustic and visual signals for the twelve double hour, and combinations of two different acoustic signals for the five night watches, The mechanism of this signal generation system is triggered by a copper ball which is mechanically digitized time keeping signal, and is generated from the water clock. The time announcing system consisted four parts: 1) the mechanical amplifier which changes small copper to heavy steel ball, 2) day time announcing system, 3) night time announcing system, 4) sounding mechanism. The time announcing system of King Seong's Striking Clepsidra is remotely related to the Arabic clock system, however, it does have world-widely distictive mechanisms of its era, such as mechanical amplifier, self-weight rachet mechanism, and resetable mechanical computer etc.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.12
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• pp.1022-1032
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• 1989

King Sejong's Striking Clepsydra was an elaborate timekeeping and annunciating system incorporating biological automata capable of annunciating hours, intervals and night-watches based on Shou-shih calindrical systems automatically. In this paper the author has studied the original manuscripts on the Striking Clepsydra [Sejong sillock, 65: 1a-3b ff` 16th year, 7th month(1434)] from the technical point of view undertaking a close analysis of this monumental clock and aiming to our modern understanding of the full degree of delicate mechanisms and sophisticated controls built into the night-watch and division announcing clockwork(jackwork). Based on the input/output model, timekeeping, ball-rack, ball-relay, and audible time-indicating mechanisms were synthesized reconstructing night-watch annunciating systems. It revealed that the night-watch and division announcing processes were entirely renewed automatically. Historical and philological data concerning the improvements of the proposed model were discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.697-701
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• 1996

King Sejong's Striking water-clock which brought in use on the first of July in 1434 was mainly composed of timekeeping and time announcing parts signalling twelve double-hours, and five night-watches and night-watch-divisions automatically by means of ball-operating jackworks. The clock was arranged with dual timekeeping system, the one for a full day(twelve double-hours) and the other for five night-watches achieving twelve double-hours and one-hundred interval horary systems. The vessels were arrayed in inflow-type water-clock, a large reservoir on the highest story, a constant-level tank for supplying water to the measuring vessel evenly in the middle, and the lowest tank to receive water from the above constant-level tank. An indicator-rod on the float was raised upwards depending on the water-level increase to show timing scales and also to release small bronze balls from the ball-rack mechanisms implanted on the measuring vessel to signal timing intervals.

• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.221-232
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• 2012

We analyzed the manufacturing procedure, specifications, repair history, and details of celestial movements of the water-hammering type $Honsang$ (celestial globe). Results from our study on the remaining $Honsangs$ in China and Japan and on the reconstruction models in Korea were applied to our conceptual design of the water-hammering type $Honsang$. A $Honui$ (armillary sphere) and $Honsang$ using the water-hammering method were manufactured in $Joseon$ in 1435 (the 17th year of King $Sejong$). $Jang$ $Yeong-Sil$ developed the $Honsang$ system based on the water-operation method of $Shui$ $y{\ddot{u}}n$ $i$ $hsiang$ $t'ai$ in China. Water-operation means driving water wheels using a water flow. The most important factor in this type of operation is the precision of the water clock and the control of the water wheel movement. The water-hammering type $Honsang$ in $Joseon$ probably adopted the $Cheonhyeong$ (天衡; oriental escapement device) system of $Shui$ $y{\ddot{u}}n$ $i$ $hsiang$ $t'ai$ in China and the overflow mechanism of $Jagyeongnu$ (striking clepsydra) in $Joseon$, etc. In addition to the $Cheonryun$ system, more gear instruments were needed to stage the rotation of the $Honsang$ globe and the sun's movement. In this study, the water-hammering mechanism is analyzed in the structure of a water clock, a water wheel, the $Cheonhyeong$ system, and the $Giryun$ system, as an organically working operation mechanism. We expect that this study will serve as an essential basis for studies on $Heumgyeonggaknu$, the water-operating astronomical clock, and other astronomical clocks in the middle and latter parts of the $Joseon$ dynasty.

• Publications of The Korean Astronomical Society
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• v.36 no.3
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• pp.65-78
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• 2021

Jagyeokru, an automatic striking water clock described in the Sejong Sillok (Veritable Records of King Sejong) is essentially composed of a water quantity control device and a time-signal device, with the former controlling the amount or the flow rate of water and the latter automatically informing the time based on the former. What connects these two parts is a signal generating device or a power transmission device called the 'Jujeon' system, which includes a copper rod on the float and ball-racked scheduled plates. The copper products excavated under Gongpyeong-dong in Seoul include a lot of broken plate pieces and cylinder-like devices. If some plate pieces are put together, a large square plate with circular holes located in a zigzag can be completed, and at the upper right of it is carved 'the first scheduled plate (一箭).' Cylinder-like devices generally 3.8 cm in diameter are able to release a ball, and have a ginkgo leaf-like screen fixed on the inner axis and a bird-shaped hook of which the leg fixes another axis and the beak attaches to the leaf side. The lateral view of this cylinder-like device appears like a trapezoid and mounts an iron ball. The function of releasing a ball agrees with the description of Borugak Pavilion, where Jagyeokru was installed, written by Kim Don (1385 ~ 1440). The other accounts of Borugak Pavilion's and Heumgyeonggak Pavilion's water clocks describe these copper plates and ball releasing devices as the 'Jujeon' system. According to the description of Borugak Pavilion, a square wooden column has copper plates on the left and right sides the same height as the column, and the left copper plate has 12 drilled holes to keep the time of a 12 double-hours. Meanwhile, the right plate has 25 holes which represent seasonal night 5-hours (Kyeong) and their 5-subhours (Jeom), not 12 hours. There are 11 scheduled plates for seasonal night 5-hours made with copper, which are made to be attached or detached as the season. In accordance with Nujutongui (manual for the operation of the yardstick for the clepsydra), the first scheduled plate for the night is used from the winter solstice (冬至) to 2 days after Daehan (大寒), and from 4 days before Soseol (小雪) to a day before the winter solstice. Besides the first scheduled plate, we confirm discovering a third scheduled plate and a sixth scheduled plate among the excavated copper materials based on the spacing between holes. On the other hand, the width of the scheduled plate is different for these artifacts, measured as 144 mm compared to the description of the Borugak Pavilion, which is recorded as 51 mm. From this perspective, they may be the scheduled plates for the Heumgyeonggak Ongru made in 1438 (or 1554) or for the new Fortress Pavilion installed in Changdeokgung palace completed in 1536 (the 31^st year of the reign of King Jungjong) in the early Joseon dynasty. This study presents the concept of the scheduled plates described in the literature, including their new operating mechanism. In addition, a detailed model of 11 scheduled plates is designed from the records and on the excavated relics. It is expected that this study will aid in efforts to restore and reconstruct the automatic water clocks of the early Joseon dynasty.