It’s not uncommon to have these at the end of the runway but it’s the first time I’ve seen one that seems to be solely to protect the ILS antennas…

I will correct myself I’ve seen arresting walls like this protecting non-human life endangering equipment on military runways where a loss of a single aircraft and either a single pilot or a crew can be less significant than the operational degradation of the airfield.

I actually wonder if there is some requirement in South Korea to harden civilian airfields due to their likely dual use in case of a conflict.