Inquisitive minds want to know.
I have been a proponent of facilities like this for a long time and would like to see more around the world. The more people understand about them the more likely they will find ways to make them economically viable in their areas.
I wonder if the owners of these facilities have looked into an arrangement with the Korean Navy to train their sailors in submarine rescue? A deep pool like this could also be used for helicopter escape training. Not many of the world's navies are big enough to need facilities like this full time, let alone justify their cost. There might be some win-win solutions lurking in there somewhere.
There was some talk about converting a surplus missal silo in the US for dive training but they haven't worked out.