Sejong the Great Class (Sejongdaewang Class) ships are Aegis guided missile destroyers of the Republic of Korea Navy (ROKN).
A long side view of the ROKN Aegis guided missile destroyer Sejong the Great (DDG 991).
The Republic of Korea Aegis destroyer Sejong the Great participating in the International Fleet Review.
Sejong the Great Class (Sejongdaewang Class) destroyers are armed with Chung Sang Eo (Blue Shark) torpedoes.
The Sejong the Great Class is fitted with a RIM-116 Rolling Airframe Missile launcher.

Sejong the Great Class destroyer

The Sejong the Great Class (Sejongdaewang Class) guided missile destroyers are being developed under the Korean Destroyer eXperimental (KDX) programme of the Republic of Korea Navy (ROKN).

"Sejong the Great Class destroyers are equipped with a combined gas turbine (COGAG) propulsion system."

Three units are being built by Hyundai Heavy Industries and Daewoo Shipbuilding & Marine Engineering. The destroyer class is also referred to as KDX-III

The lead ship in its class, Sejong the Great (DDG 991), was launched in May 2007. The destroyer was commissioned in December 2008. The second destroyer, Yulgok Yi I (DDG 992), was launched in November 2008 and delivered in September 2010.

The vessel entered service with the ROKN in June 2011. The third destroyer, Seoae Ryu Seong-ryong (DDG 993), was launched in March 2011. It is scheduled for commission in 2012.

KDX-III destroyer design

Apart from the longer hull, the overall design of KDX-III is identical to that of the Arleigh Burke Class destroyer. The KDX-III destroyers are the largest surface warships to carry the Aegis weapon system.

The destroyer has an overall length of 165m, beam of 21m and draft of 6m. The standard displacement of the ship is 7,700t and full load displacement is 10,000t.

The vessel can accommodate more than 300 crew members.

Sejong the Great destroyer missions

Sejong the Great Class destroyers are deployed in conventional naval warfare, anti-submarine warfare and anti-air warfare operations.

The destroyer conducts accurate strikes on the main enemy targets, and can protect mobile and convoy fleets from enemy aircraft and guided missiles.

It also supports the MASOC (Maritime Air Support Operation Centre) which controls all tactical aircraft operating on the sea.

The KDX-III destroyers allow the ROKN to protect Korean waters from air, surface, and subsurface threats.

Command and control

KDX-III destroyers are equipped with the Aegis combat system developed by Lockheed Martin. The Aegis system consists of SPY-1 radar and other components including SPY-1D (V) transmitter and MK 99 fire control system.

The radar acquires and tracks multiple targets such as aircraft and missiles.

This system, integrated with the MK 41 vertical launching system, delivers missiles against multiple threats in different attack scenarios. It can be used as an integrated single ship system and in a ship-to-ship network.

In July 2010, the Sejong the Great (DDG 991) successfully completed the combat system ship qualification trials (CSSQT) at the Pacific Missile Range Facility, off the Hawaiian island of Kauai.

Sejong the Great weapons

The Sejong the Great Class is armed with 16 SSM-700K Hae Sung long-range anti-ship missiles and 32 Hyunmoo III land attack missiles.

Two MK 41 vertical launch systems (VLS), one with 48 cells and another with 32 cells, are fitted forward and aft of the vessel for SM-2 Block IIIB missiles.

The ship point-defence is provided by a single 30mm Goalkeeper close-in weapon system (CIWS) and a RIM-116 rolling airframe missile (RAM) block 1 21-round launcher.

The main gun fitted forward is a 127mm L62 Mk-45 Mod 4 naval gun. The gun can fire at a rate of 16 to 20 rounds a minute for a range of 24km.

The anti-submarine weaponry includes K-ASROC Hong Sahng-uh (Red Shark) anti-submarine rockets (ASROC) and K745 LW Cheong Sahng-uh (Blue Shark) torpedoes.

A total of 16 rockets are fired from the launcher fitted on the aft.

The ASW control software is supplied by Kongsberg Maritime.

Sensors / radars

The AN/SPY-1D multifunction radar and four antenna arrays are housed in a single deck house. The ship is also equipped with AN/SPG-62 I/J band fire control radar, Atlas Elektronik bow-mounted DSQS-21 BZ-M sonar and MTeQ towed array sonar system.

Helicopter system

The KDX-III destroyers have a stern helicopter deck to support the operations of two Westland Lynx Mk 99 ASW helicopters. Hangar facilities are provided for the helicopters.


Sejong the Great Class destroyers are equipped with a combined gas turbine (COGAG) propulsion system.

"The lead ship in its class, Sejong the Great (DDG 991), was launched in May 2007."

Four General Electric LM2500 gas turbines driving the two shafts provide a total power output of 75MW.

The ship systems are powered by three Rolls-Royce AG9140RF gas turbine generator sets. The propulsion system provides a top speed of 30kt and a maximum range of 5,500nm at 20kt.

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