On May 5, 1978 North Korea issued a 5 stamps to commemorate their maritime heritage. The stamps depict 5 ships and various aircraft and other modes of transportation (A very topical minded issue ;). The stamps were perforated 13.¼ and were also issued in a Sheet of 5 plus 1 label.
The first ship identified is the Cargo Freighter Man Gyong Bonk. Google provided that the ship may be misidentified in the Scott Catalogue and should be the Man Gyong Bong. Not to be confused with a ship with the same name constructed in 1992, this one was recently touted as possibly the worst cruise ship in the world. You can read the article here: http://www.news.com.au/travel/holiday-ideas/is-north-koreas-man-gyong-bong-the-least-luxurious-cruise-ship-in-the-world/story-e6frfqf9-1226127814789<
2ch Man Gyong Bong
The 5ch value depicts the freighter Hyok Sin. Originally the Kyokuyo Maru completed in 1957, she was sold to North Korea in 1974.
5ch Hyok Sin
The next ship is the freighter Chong Chon Gang on the 10ch value. Completed according to one source in 1977, as of 2009 she was still registered to a North Korean owner.
10ch Chong Chon Gang
The tanker Son Bang is featured on the 30ch value. I have yet to get further information on this ship, if you have some please email me and let me know.
30ch Son Bang
The last stamp features the freighter Tae Dong Gang. Completed in 1976 she was built in North Korea and as of 2009 was still in service.
50ch Tae Dong Gang
The designs of the stamps are visually appealing and as stated earlier appeal to a wide variety of thematic or topical collectors. Not worth very much in terms of catalogue value, as far as I am concerned they are a nice addition to my general world wide and ships on stamps collection.