This is the ROKS PKM 287, a South Korean Chamsuri class patrol ship, classified as a Patrol Killer Medium. The ROK Navy has over 80 units in service and one of them as strayed a little too far south. This ship is part of a diorama that I like to call either "Pagharang - Interception" or "Mabuhay! - Welcome to the Philippines!". It is a fictional scenario in which this vessel has entered Philippine waters and is stopped by force by a Philippine Navy ship as well as a Philippine Air Force helicopter. The UH-1 is rendering support, holding the crew of this vessel at gunpoint while the Philippine vessel is sending a boarding party on a RHIB.
During my resarch to find a suitable vessel for a possible scenario like this, I came across the Chamsuri class of ships which happened to be an exact fit to the Pegasus class ship that I still had laying around - one hull less to scratchbuild. The superstructures were cut off and the deck was sanded smooth. Then construction of the new superstructure could begin. it was an easy and quick build. The mast is made almost entirely out of copper wire. The weapons (40mm AA and 20mm gatling guns) were also scratchbuilt with styrene and copper wires. The bridge windows are made of decal stripes. Various antennas are from stretched sprue.
The Philippine ship (part 1 of the diorama) is the BRP Mariano Alvarez and can also be found on this site.