It would seem that out neighbours have got rid of their dog. Either that or the dog has passed away but I think the former is more likely. We suddenly noticed one day that we couldn't hear it when we expected to - i.e. all the time. I can't say I will miss it. It was no fun to be woken up early on Sundays and to put up with it's barking for eight hours or so.
Korean housing does not lend itself to noisy pets. Here, apartments or so called 'villas' are boxed together tightly and their is very little space between buildings. You can hear pretty much everything the neighbour does if they are a little loud so having a dog that yaps a lot can be a big distraction for people. I think the kids next door will miss the dog but certainly not us but I wonder what actually made them offload their pet.