To quote KJN Gene Gause...
"I could tell you, but then I'd have to Pyung Soo you."
Just kidding. More information to come.
Keeping secrets is folly, ergo the revelation can be found below:
TU SAL BEOP : 투살법 : 投沙法 : "sand-throwing principle"
Compare with SA LAHK BUP & TOO SUHK SOOL (possible duplication)