You may find these about Seoul, or if you just want to find one without trying, during Operation: Joule (after Operation: Heaven Sent), you will be requested to destroy one of these devices. What it does is that it enrages the citizens nearby and make them come after your agents. To destroy it, you have to break the three plates that rotate on its top. However, it will drop into an invulnerable state from time to time, so kill the LEGION forces to bide your time while it is down.
On the city map, you may find a Hate Machine Emplacement by looking for the little disgruntled face blue icons scattered around.