Chamsuri-class patrol boats are workhorses of Republic of Korea Navy, fending off North Korean intruders from ROK waters since 1970s, conducting anti-smuggling, anti-piracy and fisheries protection patrols while not deployed near DMZ. One boat, PKM-357 was lost to a North Korean attack (and later was filmed in a movie about that incident, "Northern Limit Line"). Also boats of that class were exported and/or gifted to a number of countries, including Philippines, Kazakhstan, Timor, Bangladesh and Ghana.
First batch of Chamsuri-class included 27 boats. Now most of them are retired and sold and/or scrapped.
In 1980s building of second batch, which differed with more powerful armament, now consisting of one 30-mm Emerlec mount forward and two 20-mm Sea Vulcan gun mounts in place of 40mm/60 Mk3 Bofors mount aft, somewhat different superstructure and mast, began. 28 boats were built to this design.
In 1990s the latest batch of chamsuris was built - it had the heaviest armament of the entire class, consisting of one 40-mm bofors in Daewoo ADS powered mount forward, two Sea Vulcans aft and two machine guns amidships. Also some chaff/flare launchers were added. Most of batch-3 boats continue to serve nowadays, and PKM-357 was of this type.
Finally, in 2008-2014, 21 patrol boats of GA826-Class were comissioned by the ROK Navy. While not being considered to be a batch of Chamsuri-Class, these small harbor defence boats are actually smaller versions of Chamsuris with reduced armament and shorter hull.
In 2000s, several batch 1 boats of Philippine Navy were "uprgaded" by removing forward 30-mm Emerlecs, placing aft 40-mm Bofors mk3 in place of it and adding 4 12,7-mm M2 Brownings aft, as well as adding an ability to carry a RHIB in place of aft bofors mount.