Top 100 Water Clock Vocabulary Words | South Korea

Before a clock could tell everyone the time, someone had to make passing time visible—and then make that information travel. This guide teaches 100 English vocabulary entries for water clocks, using Korean scientific heritage to connect containers, moving parts, sound signals and historical evidence. You will learn to explain a mechanism without losing the reader halfway along the water channel.

The National Palace Museum of Korea’s account of Jagyeokru makes South Korea a valuable setting for this lesson. It connects Jang Yeong-sil, King Sejong and public timekeeping, while its collection language also teaches a quieter skill: distinguishing a restored model from surviving historical material. Both kinds of precision matter in English.

Use the list as a set of tools. Begin with the diagnostic, learn one group, then describe a diagram or rewrite a caption from memory. “Top 100” is a curated learning list, not a frequency ranking. Our simple mechanism and numerical examples are teaching models, clearly separated from claims about the historical instrument.

Start with the learner and context

• A three-question starting point
• Korean timekeeping: a technical system with a public role

Vocabulary groups: all 100 entries

• Name the instrument and its setting · entries 1–10
• Trace the containers and openings · entries 11–20
• Describe water as a changing quantity · entries 21–30
• Follow the visible indicator · entries 31–40
• Connect one movement to another · entries 41–50
• Separate measurement from notification · entries 51–60
• Measure time carefully · entries 61–70
• Check the model’s limits · entries 71–80
• Read surviving objects and later reconstructions · entries 81–90
• Explain the chain in your own words · entries 91–100

Worked learning, practice and next steps

• From collected water to elapsed time
• The museum label that became too confident
• Practice: change one condition and explain the result
• Questions about water-clock language
• Next: preserve the condition when you paraphrase
• Sources and further reading

First, describe what changes when a container fills: its capacity, its water volume or its water level? Capacity normally stays fixed, while volume and level change. Second, explain how a changing level could lead to a sound. Third, distinguish “the original clock survives” from “some jars from a later rebuilt clock survive”. Each question reveals a different kind of precision.

If the quantities blur together, begin with entries 11–30. If you can name parts but cannot connect them, begin with entries 31–60 and draw arrows with verbs on them: rises, releases, strikes. If the mechanism is clear but the historical sentence becomes too confident, use entries 81–100 and the source-reading exercise.

For a learner, the best first output is a short explanation with one labelled assumption. For a parent, ask what the diagram leaves out. For a teacher, change one condition after the learner has explained the model. A copied explanation may remain fluent while failing to respond to that change; an understood explanation can adapt.

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The National Palace Museum of Korea’s scientific-achievement gallery identifies its displayed Jagyeokru as a restored model. Its account credits Jang Yeong-sil with creating the self-striking water clock under King Sejong and states that it became the national time standard in 1434. The source also discusses timekeeping as an instrument of royal administration and social order.

The museum’s collection account on Google Arts & Culture adds a crucial distinction: the original was not preserved intact, and several jars remain from the clock rebuilt in 1536. These are not contradictory statements about one untouched object. They refer to different moments in the instrument’s history.

The historical setting is Joseon Korea; the present-day museum is in South Korea. Do not write as if a modern state commissioned a fifteenth-century instrument. Nor should this one courtly case stand for every community or every tradition of timekeeping on the Korean peninsula. It is a specific, well-documented route into a wider history.

We use the museum’s romanised name Jagyeokru and explain it as a self-striking water clock. Other sources may use different romanisations, including Jagyeongnu. Recognising variation helps readers connect sources without assuming that every spelling marks a different machine. The rest of the list is primarily English vocabulary useful for explaining mechanisms and evidence.

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The opening terms identify the subject and its historical context. A specialised word such as clepsydra can be useful, but explain it in ordinary English before expecting a reader to follow a technical account.

Entry	Meaning and usage	Natural collocation	Original contextual example
1. water clock	A timekeeping device using a measured change in water quantity or level.	historic water clock	The Seoul museum account helps us explain a water clock without imagining a modern wristwatch.
2. clepsydra	A formal English word for a water clock; plural clepsydras or clepsydrae.	ancient clepsydra	The learner explains clepsydra once, then uses water clock for a younger audience.
3. timekeeping	The practice of measuring or maintaining an account of time.	public timekeeping	Our discussion connects timekeeping with shared routines and public communication.
4. horology	The study and craft of time measurement and timekeeping instruments.	history of horology	The museum project introduces horology through one clearly bounded example.
5. Jagyeokru	A romanised Korean name for a self-striking water clock; spellings vary across sources.	Jagyeokru mechanism	The label preserves Jagyeokru and adds an English explanation beside it.
6. Joseon	The name of a historical Korean dynasty; a proper noun, not a modern nationality label.	Joseon court	The passage places the commission in the Joseon court rather than modern government.
7. court	The ruler's household and associated officials; not a sports area in this sense.	royal court	The royal court supplied a political setting for the timekeeping instrument.
8. commission	An instruction or order to create a work.	royal commission	A commission tells us who requested the instrument, not every detail of its construction.
9. inventor	A person who creates a new device or method.	credited inventor	The learner identifies the credited inventor while recognising the wider work behind an instrument.
10. instrument	A device serving a precise observational, measuring or technical purpose.	scientific instrument	Calling the clock a scientific instrument directs attention to how it measures something.

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A mechanism becomes easier to understand when you can name where material enters, gathers and leaves. These words transfer to diagrams in science, engineering and everyday explanations of household systems.

Entry	Meaning and usage	Natural collocation	Original contextual example
11. reservoir	A container or place holding a supply of liquid.	supply reservoir	The simplified drawing labels the reservoir before following the water's path.
12. vessel	A container used to hold a substance; also a boat in other contexts.	water vessel	Here, vessel means a container and has nothing to do with sailing.
13. jar	A usually broad-mouthed container for holding substances.	surviving jar	A surviving jar is evidence of part of the clock, not necessarily the complete mechanism.
14. basin	An open bowl-like container or depression holding liquid.	receiving basin	The model sends water into a receiving basin where the level can be observed.
15. inlet	An opening through which a substance enters.	water inlet	The inlet arrow points into the container rather than away from it.
16. outlet	An opening through which a substance leaves.	controlled outlet	The outlet belongs to the model's water path, not to an electrical circuit.
17. aperture	An opening, especially a defined or measured one; formal or technical.	small aperture	The lesson uses aperture as a precise alternative to hole when discussing the model.
18. channel	A passage guiding the movement of liquid or another material.	water channel	A channel connects two parts in the explanatory diagram.
19. overflow	Liquid passing beyond a container's normal capacity or a designed level.	overflow channel	The drawing distinguishes an overflow channel from the main outlet.
20. capacity	The amount a container can hold.	reservoir capacity	Capacity describes what the reservoir can hold, not what it currently contains.

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Flow, volume, level and rate are related but not interchangeable. A container can hold the same volume at different levels if its shape changes. State what you are measuring before doing a calculation.

Entry	Meaning and usage	Natural collocation	Original contextual example
21. flow	Movement of a liquid or gas from one place to another.	steady flow	The classroom explanation assumes a steady flow and labels that assumption clearly.
22. flow rate	The amount of fluid passing a point per unit time.	constant flow rate	A constant flow rate makes the example calculation straightforward.
23. volume	The three-dimensional amount of space occupied by a substance.	collected volume	The learner records collected volume in millilitres rather than calling it water height.
24. level	The height of a liquid surface relative to a reference.	rising water level	A rising water level provides a visible change in the simple model.
25. head	A fluid-mechanics measure related to pressure expressed as an equivalent fluid height.	water head	The technical note explains water head before using it to discuss changing flow.
26. pressure	Force per unit area exerted on a surface.	water pressure	The learner distinguishes water pressure from the amount of water collected.
27. gravity	The attraction that gives objects weight near Earth and influences falling water.	gravity-driven flow	Gravity-driven flow does not mean that the water supplies unlimited energy.
28. discharge	Fluid leaving a system, or the rate at which it leaves.	outlet discharge	The report states whether discharge means a quantity or a rate in that sentence.
29. leakage	Unintended escape of liquid or gas.	unwanted leakage	Leakage would make the collected volume differ from the intended amount.
30. regulation	Control intended to maintain a process within chosen conditions.	flow regulation	The explanation links flow regulation with reliable timing rather than with legal rules.

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The water does not need to carry a tiny clock face. A changing level can move a float, which can move an indicator or trigger another action. These entries describe a simple conceptual chain.

Entry	Meaning and usage	Natural collocation	Original contextual example
31. float	An object supported at a liquid surface that can move with its level.	rising float	The learner follows the rising float in the simplified mechanism drawing.
32. rod	A long, relatively slender rigid component.	indicator rod	The indicator rod makes the float's movement easier to see in the model.
33. indicator	A feature or device showing a state or quantity.	level indicator	The indicator displays a change without necessarily producing a sound.
34. scale	A set of marks used to read a measured quantity.	graduated scale	The scale needs labelled units before a reader can interpret its marks.
35. graduation	An individual division or mark on a measuring scale.	scale graduation	One graduation represents a defined interval in the classroom example.
36. pointer	A component that directs attention to a position on a scale.	moving pointer	The moving pointer is a display feature in this hypothetical diagram.
37. threshold	A value or position at which a specified event is triggered.	trigger threshold	The float reaches a threshold before the model releases a ball.
38. trigger	A component or event that starts another action.	mechanical trigger	The trigger begins a sequence rather than measuring every part of it.
39. release	To free a held component or substance; also the resulting event.	ball release	The model's ball release follows the float reaching its marked position.
40. reset	To return a system or component to a starting condition.	manual reset	The classroom model requires a reset between demonstrations.

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Mechanical vocabulary helps you say how an action is passed onward. The diagrams used in this guide are simplified illustrations, not detailed reconstructions of every part of Jagyeokru.

Entry	Meaning and usage	Natural collocation	Original contextual example
41. mechanism	Connected parts arranged to produce an action.	striking mechanism	The striking mechanism communicates time after another part measures its passage.
42. linkage	Connected components transmitting motion or force.	mechanical linkage	The linkage joins the float's movement to a later action in the diagram.
43. lever	A rigid part that turns around a support to transmit force or motion.	pivoted lever	The example lever changes position when the small ball reaches it.
44. pivot	A support or point about which something turns.	fixed pivot	The learner circles the pivot before describing the lever's movement.
45. ball	A rounded component that can roll or fall within a mechanism.	rolling ball	A rolling ball carries the model's action from one stage to the next.
46. track	A defined path guiding a moving component.	inclined track	The track guides the ball rather than recording time by itself.
47. incline	A slope; also a verb meaning to slope or tilt.	gentle incline	The diagram uses an incline to illustrate how the ball can move downward.
48. impact	A collision or strike between objects.	ball impact	The student identifies the impact that starts the next movement.
49. transmission	The passing of motion, force or information between parts.	motion transmission	The explanation separates motion transmission from the final audible signal.
50. automaton	A mechanism that performs a sequence of actions automatically; plural automata.	mechanical automaton	An automaton can repeat an action without being a modern computer-controlled robot.

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Knowing a time and announcing it are different jobs. A signal can make information available to someone who is not watching the measuring device. This distinction also appears in modern alarms and monitoring systems.

Entry	Meaning and usage	Natural collocation	Original contextual example
51. signal	An action or sign carrying information.	audible signal	The audible signal lets a listener know that a defined time point has arrived.
52. bell	A sounding instrument usually struck to produce a resonant tone.	struck bell	A bell provides one kind of sound in discussions of historical time signals.
53. gong	A metal percussion instrument struck to make sound.	sounding gong	The account mentions a gong as part of communicating time.
54. drum	A percussion instrument with a stretched membrane that is struck.	drum signal	The learner distinguishes a drum signal from the sound of metal being struck.
55. striker	A component that hits another object to produce an effect or sound.	mechanical striker	The striker belongs to the sounding stage of the model.
56. audible	Able to be heard.	audible notification	An audible notification can reach a person who is not watching the scale.
57. visual	Relating to sight.	visual display	A visual display and an audible signal communicate information through different senses.
58. notification	An act of informing someone that something has happened.	time notification	Time notification is separate from the measurement that supports it.
59. relay	To pass information or an action onward.	relay a signal	The passage explains how people could relay a signal beyond the original instrument.
60. synchronise	To align timing between events or systems.	synchronise activities	A shared signal can help people synchronise activities without owning individual clocks.

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A date, a duration and a repeating period answer different questions. These words let you discuss what an instrument measures and how its output is compared with an accepted reference.

Entry	Meaning and usage	Natural collocation	Original contextual example
61. interval	The time or distance between two points or events.	time interval	The task measures an interval rather than asking for a date on a calendar.
62. duration	The amount of time an event lasts.	measured duration	The duration of the demonstration differs from the time at which it begins.
63. elapsed time	Time that has passed since a specified starting point.	record elapsed time	The table records elapsed time from the moment collection begins.
64. cycle	A sequence that repeats or returns to its starting state.	repeating cycle	The learner identifies what must happen before another cycle can begin.
65. period	The time taken for one complete repeating cycle, in technical usage.	oscillation period	The comparison with a pendulum introduces period without claiming the water clock uses one.
66. standard	An agreed or authoritative reference used for comparison.	time standard	The museum account describes a clock serving as a time standard in its historical setting.
67. calibration	Checking or relating an instrument's indications to a reference.	scale calibration	Calibration connects marks on the model with known time intervals.
68. accuracy	Closeness of a result to an accepted reference or true value.	timing accuracy	Accuracy cannot be established merely because a display has many marks.
69. precision	Consistency or fineness of measurement; distinguish it from accuracy.	repeatability and precision	Repeated similar readings can show precision while still sharing a systematic error.
70. resolution	The smallest change an instrument or display can distinguish.	scale resolution	Closer marks improve scale resolution only if the reader can distinguish them meaningfully.

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A tidy calculation depends on its assumptions. The purpose of these words is not to make every answer uncertain; it is to show exactly which conditions make a conclusion justified.

Entry	Meaning and usage	Natural collocation	Original contextual example
71. error	A difference between a result and a reference, or a mistake in ordinary use.	timing error	The lesson distinguishes measured timing error from a copying mistake.
72. drift	A gradual change in a reading or system's behaviour over time.	timing drift	The fictional test shows timing drift rather than one isolated wrong reading.
73. variation	A difference or change across observations.	flow variation	Flow variation complicates the assumption that equal volumes always represent equal intervals.
74. constant	Remaining unchanged within the stated model or conditions.	constant rate	The calculation works only because the rate is treated as constant.
75. variable	A quantity or factor that can change.	measured variable	The learner states which variable is observed and which is held fixed.
76. assumption	A condition accepted for the purpose of reasoning or modelling.	simplifying assumption	The constant-rate assumption makes this a teaching model rather than a complete reconstruction.
77. estimate	An approximate judgment or value.	time estimate	An estimate should not be presented as an exact historical measurement.
78. repeatability	Agreement between results obtained under the same specified conditions.	test repeatability	The group compares repeated trials to discuss repeatability.
79. reference	A source or value used for checking another statement or measurement.	reference clock	The test compares the model's indication with a reference clock.
80. uncertainty	A stated limit to knowledge or measurement confidence.	measurement uncertainty	The report acknowledges uncertainty instead of claiming impossible exactness.

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Historical objects rarely arrive with every original part and a complete instruction manual. Museum language tells you what survives, what was recreated and what evidence supports the connection.

Entry	Meaning and usage	Natural collocation	Original contextual example
81. chronology	The order and dating of historical events.	clear chronology	A chronology separates the earlier commission from later rebuilding.
82. reconstruction	A later attempt to recreate an earlier object, arrangement or event.	working reconstruction	A working reconstruction is informative without being the original instrument.
83. remnant	A surviving part of something once more complete.	surviving remnant	The jar is discussed as a remnant, not silently presented as the entire clock.
84. original	The first or source object in a stated comparison; the reference must be clear.	original mechanism	The learner asks whether original refers to the fifteenth-century mechanism or a later rebuild.
85. replica	A copy made to resemble another object.	display replica	The display replica is labelled so visitors can distinguish it from surviving historical material.
86. archive	A collection of preserved records, or the institution keeping them.	archival record	An archival record can support a date that the object alone cannot reveal.
87. annal	A historical record arranged by year; usually used in the plural annals.	historical annals	The essay refers to annals as records rather than treating them as modern laboratory notes.
88. provenance	The documented origin and history of an object.	object provenance	Provenance helps explain why a surviving vessel is associated with a particular instrument.
89. attribution	Identification of a maker, source or origin.	qualified attribution	The label uses a qualified attribution when the evidence does not justify certainty.
90. context	The surrounding circumstances that help explain meaning.	historical context	The clock's political context adds meaning beyond its moving parts.

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These final entries help turn labels into reasoning. Use sequence for order, cause for the relationship between events, and limitation for what your model cannot establish.

Entry	Meaning and usage	Natural collocation	Original contextual example
91. sequence	An ordered series of events or actions.	mechanical sequence	The student explains the sequence from changing water level to a sound signal.
92. cause	A factor that produces or contributes to an effect.	identify a cause	The task asks for a cause, so the learner must connect two stages.
93. effect	A result produced by an action or condition.	observable effect	The rising float is an observable effect in the simplified demonstration.
94. condition	A circumstance required for a statement or process to apply.	stated condition	The calculation's condition is a constant flow rate throughout the interval.
95. limitation	A boundary on what a method, model or source can establish.	model limitation	The learner names a limitation before comparing the model with a historical clock.
96. analogy	A comparison used to explain a relationship.	useful analogy	The analogy of a filling container explains accumulation without reproducing the complete mechanism.
97. demonstrate	To show an action or support an explanation with an example.	demonstrate the principle	The teacher uses a paper diagram to demonstrate the principle of sequential triggering.
98. infer	To draw a conclusion from evidence.	infer a function	A shape may suggest a function, but the learner checks the museum record before asserting it.
99. qualify	To restrict a claim with an accurate condition or limit.	qualify a conclusion	We qualify the conclusion by saying this model rather than all water clocks.
100. paraphrase	To express the same meaning in different words.	accurate paraphrase	An accurate paraphrase preserves the difference between surviving jars and a complete original clock.

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Consider an invented classroom model. Water enters a collecting vessel at a constant rate of 20 millilitres per minute. Starting from zero collected volume, 100 millilitres represents 5 minutes because 100 ÷ 20 = 5. The vocabulary relationship is volume divided by flow rate equals elapsed time, provided the rate is constant and the starting condition is known.

Now change the rate to 25 millilitres per minute. The same 100 millilitres represents 4 minutes. A learner who repeats “100 millilitres means 5 minutes” has memorised a result while losing its condition. The correct explanation updates the relationship: the time depends on both the collected amount and the rate.

Next distinguish volume from level. If two vessels have different shapes, the same added volume need not produce the same rise in water level. A scale that marks equal heights does not automatically mark equal volumes, and equal volumes do not automatically mark equal times when flow varies. This is why a neat drawing should not be mistaken for a complete account of instrument calibration.

Finally, add a hypothetical notification mechanism: a float rises with the water, reaches a marked threshold and releases a small ball; the ball moves a lever that produces a sound. This sequence illustrates measurement, triggering and notification. It is not offered as a complete reconstruction of the historical clock. The learning goal is to explain how one change can initiate another.

Diagnostic breakpoint: ask “What if some water leaks away?” The collected volume may no longer represent the intended inflow. Ask “What if the container becomes wider near the top?” The relationship between level and volume changes. Ask “Does a bell ringing prove the time is accurate?” No: a notification can work even when the underlying measurement is wrong.

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Original illustrative dialogue: “I wrote that this is the original clock from 1434,” says Min. “What does the label call the display?” asks Hana. “A restored model.” “Then keep that phrase. It tells the visitor what they are looking at.” Min revises the first sentence before adding any more impressive vocabulary.

A careful short account could say: “The museum presents a restored model of Jagyeokru, associated with the timekeeping system established under King Sejong. Its collection account separately discusses surviving jars from a later rebuilding.” The sentence does not compress a model, an earlier mechanism and later remnants into one object.

For reading practice, mark three categories in a source: what is physically present, what historical records describe and what later reconstruction proposes. A source may discuss all three in one paragraph. Your job is to keep the relationships clear, not simply collect the oldest date and attach it to the nearest noun.

There is also a useful communication question: who receives the time signal? A display serves a watcher; an audible signal serves a listener. A person can relay information beyond the instrument’s immediate location. Explaining those roles helps connect historical technology with broader ideas of public information without claiming that all societies organised time in the same way.

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Task A: choose the term. 1. The amount a container can hold is its capacity/current level. 2. Water entering per minute is a volume/flow rate. 3. The time since a starting point is elapsed time/provenance. 4. A later recreation is a reconstruction/remnant. Answers: capacity; flow rate; elapsed time; reconstruction.

Task B: an invented model collects 180 millilitres at a constant 30 millilitres per minute, starting empty. Calculate the interval and state the assumption. Answer: 6 minutes, assuming the rate remains constant and the collected amount accurately represents the inflow. Units are part of the explanation, not a decorative suffix.

Task C: keep 180 millilitres but change the rate to 45 millilitres per minute. Answer: 4 minutes. Explain in a full sentence: “The same volume takes less time to collect because the flow rate is greater.” This sentence connects the calculation with a causal relationship.

Task D: correct “The sound proves the clock is accurate.” Suggested answer: “The sound shows that the notification mechanism operated; accuracy requires comparison with an appropriate time reference.” The distinction is between successful action and correct measurement.

Task E: write a 70-word account using original, reconstruction, remnant and chronology. Then give a partner a new museum description and ask them to use the same four words appropriately. If your wording cannot change with the object, it has become a template rather than a tool.

For retrieval practice, close the page and reconstruct the model as five labelled boxes: supply, flow, changing level, trigger, signal. Explain the arrows aloud. Reopen only to check the missing relationship, then try again with a changed rate. This moves the words from recognition into speaking and reasoning.

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Is a clepsydra a Korean word? No. It is an English technical word with classical roots. Jagyeokru is the romanised Korean name used here for the particular self-striking water clock discussed by the museum.

Does automatic mean electronic? No. A mechanical arrangement can initiate a sequence without electronics. Describe the mechanism involved rather than importing assumptions from modern digital devices.

Can water clocks work without sunlight? Their measuring principle does not require a solar shadow. That distinction helps explain their difference from sundials, but it does not establish that every water clock ran perfectly or required no attention.

Are accuracy and precision the same? No. A set of readings can be very consistent and still differ from a reference. Use accuracy for closeness to the reference and explain the intended sense of precision in your context.

Can this simple model recreate Jagyeokru? No. It illustrates selected relationships. A historical reconstruction requires much more evidence about design, materials and operation.

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The published English Tuition | South Korea guide uses limiting words such as only to show how a summary can accidentally change a claim. Apply that lesson to “some surviving jars”, “a restored model” and “at a constant rate”. Each phrase limits what you are entitled to conclude.

Use the Vocabulary Learning Hub for broader English development and the retrieval-practice guide to plan short reviews. These are eduKate learning resources from Singapore; the country context does not imply a South Korean centre or programme.

A practical learning route has three products: explain the flow calculation, narrate the hypothetical mechanism, then write a museum caption that distinguishes original material from reconstruction. Keep the first attempt and a later independent attempt. Compare whether the later version preserves quantities, conditions and chronology with less prompting.

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Source notes checked on 24 October 2026. The cultural or industry records below support the factual context; dictionary entries clarify selected English senses. Definitions and teaching examples are written for this learning guide. Dates attached to events and records refer to those specific sources.

• National Palace Museum of Korea: scientific achievement and restored Jagyeokru model
• National Palace Museum of Korea collection: Self-striking Water Clock
• American Heritage Dictionary: clepsydra
• National Cheng Kung University: research on Korean water-clock reconstruction

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