In March 2013, Kim Jong-un made an inspection of the Unit 641 (제641군부대) on the south-east coast of North Korea. This KPA own some Koksan artillery (M-1978) wich are 170 mm self-propelled artilleries. They are supposed to respond to any provocation from the South Korean island, Baekryeongdo (백령도), located at 20km from the coast. Also those artilleries are stored in little houses between the mountains. I spotted some of them thanks to the photos taken during the “Leader inspection”.
This “house” containing the Koksan can be seen at 38°08’17.85″ N 124°54’59.22″ E. You can even see the 4 canons.
And another one located at 38°08’28.15″ N 124°56’41.58″ E.
In total I have spotted five houses containing 4 Koksan each for a total of 20 artillery pieces. But I have also spotted 10 other similar houses that could also contain Koksan artilleries.
KPA Unit 641.kmz (mega.co.nz)
Kim Jong Un Inspects Artillery Unit, Islet Defense Unit and Visits Fish Farm (nkleadershipwatch.wordpress.com)
Koksan (artillery) (en.wikipedia.org)