Thousand Pound Pendulum is a technique that seemingly increases one's weight/force through breathing. It has two different applications.
Go Gam-Do's Style
Go Gam-Do used this technique to disrupt the opponent's center of gravity by pulling the opponent with significant force while using this technique.[1]
Southern Style
An unnamed Priest used this technique to increase the power of his stomp, though its full effect isn't seen as Han Dae-Wi countered and completely obliterated his foot.[2]