The effects of columnar pins on the flux lines in a model High-Tc superconductor in an applied field are studied through Monte Carlo simulations. An analytic solution for a single line case is obtained and compared with the simulation results. By introducing a tilted potential, we study simulated ``IV" characteristics and the results indicate a distinct scaling behavior above and below the depinning temperature. We introduce a diverging length scale measured in terms of a ``retrapping length'' to analyze self-similar behavior across the depinning transition.

11 pages, RevTeX3.0, four figres upon request