I found about 600 of telecommunication towers in the Korean territory, most of them were constructed in 2010. According to NKEconWatch, they are Koryolink mobile phone towers. Koryolink is own by the KPTC and the Egyptian company Global Telecom with the goal of deploying a 3G mobile network in Korea.
The distance between each towers seems to vary between 3 km and 7 km.
Google Earth file : Communication by mrpanda.kmz (mega.co.nz)