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ROKS Sejong the Great (DDG-991)

Guided Missile Destroyer Warship

Naval Warfare / Ships

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Six of the Sejong the Great-class guided missile destroyers are planned for the South Korean Navy.

Authored By: Staff Writer | Last Edited: 4/6/2020 | Content ©www.MilitaryFactory.com
ROKS Sejong the Great (KD-III) (DDG-991) marks the lead ship of the class of South Korean guided missile destroyers carrying the same name. The warships, with six planned (three completed and in active service as of 2016), are comparable to the American Navy's Arleigh Burke-class warships save for a greater displacement in the Korean design and a much greater missile load. The ships was constructed under the Hyundai Heavy Industries (HHI) brand label and named after the fourth Joseon Dynasty king (1397-1450) of Korea who is credited with creating the Korean alphabet.

The growing aspirations of China in the South China Sea and the ever-present threat of war from North Korea forces South Korea to maintain a sizeable military force that includes a strong naval arm. The service's composition is quite modern and largely influenced by American design and fighting philosophy in an effort to keep the two allies in line should another bloody war erupt against the North. Sejong the Great is a step in the right direction in providing the Republic of Korea Navy (ROKN) with a lethal missile-wielding element to bring to bear - part of total war with North Korea would be neutralization of its ocean-going force, aerial denial and destruction of inland positions and infrastructure.

Destroyers of any modern navy are fast, agile vessels designed around a multi-mission mindset with both offensive and defensive capabilities as part of their genetic make-up. The ships are typically armed through a large number of missiles to deal with ranged air, land, and sea targets and carry more conventional local defensive measures by way of guns. These warships can operate independently or as part of the main ocean-going force which makes them tactically flexible and strategically valuable.

Sejong the Great displaces 8,500 tons under standard load and 11,000 tons under full load. Its length reaches 165 meters with a beam of 21.4 meters and a draught of 6.25 meters - the latter allowing it a certain quality to operate in shallower waters near shorelines. Its propulsion system is made up of 4 x General Electric LM2500 engines driving two shafts in a COGAG (COmbined Gas and Gas) arrangement - two gas turbines coupled to a single shaft with a gearbox allowing one or both engines to function at any one time - a proven fuel efficient measure. This offers the vessel a speed of over 30 knots and a range out to 5,500 nautical miles.
Internally, the warship has a crew of 300 with 400 possible under war time conditions. An AN/SPY-1D(V) multi-function radar suite drives the primary sensor and processing arrangement. An AN/SPG-62 serves as the fire control radar and a DSQS-21BZ is carried as a hull-mounted sonar. The towed array is an MTeQ unit. The LIG Next1 SLQ-200K "Sonata" functions as the vessel's Electronic Warfare (EW) suite.

In terms of armament, Sejong the Great features an total 80-cell arrangement of Mk 41 Vertical Launch System (VLS) for SM-2 Block IIIB and IV (RIM-66 Standard) medium-range surface-to-air missiles. These are contained in a 48- and 32-cell pairing, one fitted forward and the other aft. Another 48-cell grouping houses 32 x "Hyunmoo III" series cruise missiles for use against land targets and 16 x K-ASROC "Red Shark" anti-submarine missiles to deal with underwater threats. Six K745 LW "Blue Shark" torpedoes are also carried. A turreted 5" Mk 45 Mod 4 naval gun adds a more conventional attack system to the warship and is seated in its traditional place at the forecastle. The 30mm "Goalkeeper" Close-In Weapon System (CIWS) provides the necessary response to short-ranged incoming airborne threats such as cruise missiles, UAVs and aircraft. All told this gives Sejong the Great proper reach against most any naval-going threat to the warship - be they aerial, on the sea or under it in nature.

At the stern position is a full-service helicopter deck with hangar space for two Sikorsky SH-60 (or similar) Seahawk naval helicopters. These systems are kept aboard to increase the eyes and ears of the warship by carrying advanced sonar and radar equipment as well as anti-ship / anti-submarine weaponry. Helicopters also provide greater over-the-horizon vision. The landing pad can seat one additional helicopter beyond the two housed systems allowing the warship to essentially field a total of three rotorcraft under extreme circumstances. The helipad can also accept supply-delivery helicopters and rotary-winged Unmanned Aerial Vehicles (UAVs) as needed.

Sejong the Great remains in active service as of June 2016 and joined by sisters ROKS Yulgok Yi I (commissioned 2010) and Seoae Ryu Seong-ryong (commissioned 2012).


Commissioned, in Active Service
350 Personnel
Ship Class [ Sejong the Great-class ]
Ships-in-Class [ 3 ] Ship Names: Sejong the Great (DDG-991); Yulgok Yi I (DDG-992); Seoae Ryu Seong-ryong (DDG-993)
National flag of South Korea South Korea
- Blue Water Operations
- Fleet Support
- Hunter
- Direct-Attack
544 ft (165.81 m)
Width / Beam:
70 ft (21.34 m)
Height / Draught:
20.5 ft (6.25 m)
Displacement (Surface):
8,500 tons
4 x General Electric LM2500 engines in COGAG arrangement developing 100,000 horsepower to 2 x shafts.
Speed (Surface):
30 kts (35 mph)
5,501 nm (6,330 miles; 10,187 km)
1 x 80-cell Mk 41 Vertical Launch System (VLS) for SM-2 Block IIIB/IV (RIM-66) surface-to-air missile .
1 x 48-cell Vertical Launch System (VLS) housing 32 x Hyunmoo III cruise missiles and 16 x K-ASROC "Red Shark" anti-submarine missiles.
1 x RAM (Rolling Airframe Missile) Block 1
4 x SSM-700K Hae Sung anti-ship missile launcher
1 x 5" (127mm) Mk 45 Mod 4 deck gun
1 x 30mm "Goalkeeper" Close-In Weapon System (CIWS)
2 x K745 "Blue Shark" triple torpedo tube launchers.
2 x Medium Naval Helicopters - AgustaWestland Super Lynx, Sikorsky SH-60 Seahawk or similar.

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