Mostly for the OP, just partially for Novum----
Well I will say you can't fight fire with fire. If we're talking about your typical bully type he's probably already doing the intimidating or why would you be asking for help. As a very general rule, bullies pick targets they're pretty confident they can stomp fairly easlily. "Mad dogging" him is unlikely to make him leave you alone out of fear. It's just not that easy. Unfortunately the better way seems to take a while to learn correctly. You don't need to intimidate just show confidence. (real confidence not acting like it cuz that will get you hurt) Don't challenge him or stand in front of him and puff out your chest or drop into fighting stance and kiop. It's a matter of developing enough confidence in yourself that you don't need to prove to anyone (including yourself) that you aren't afraid of somthing/someone. If you have this you won't draw the attention of bullies usually. If he already has you in his sights? Stay out of his way as much as the situation commits and worry about the rest when you truly have no other choice but to fight him. Then all the rest is moot. You won't have time to think "ok now its time for my heel hook, jump spining 540 jedi sweep combo. You'll just do what you've trained.
Summation: Train hard, train often, train correctly, and build yourself into a better person. It always sounds like nonsense just like it did when "some old guy" said it to me when I was young. But, if you're prepared and well trained, you'll find that less bullies will target you. Not because they know you study TKD (if infact you do) , but because you carry yourself confidently and have presense. All animals can smell fear and doubt, why not bullies?