We present the results of a new field-theoretic simulation of
cosmological axion strings, which are eight times longer than previous
ones. We have upgraded our previous simulation of physical strings in
terms of the number of grids as well as the suite of analysis methods.
These improvements enable us to monitor a variety of quantities
characterizing the dynamics of the physical string network for the
longest term ever. Our extended simulations have revealed that global
strings do not evolve according to the scaling solution, but that its
scaling parameter, or the number of long strings per horizon, increases
logarithmically in time. In addition, we have also found that the
scaling parameter shows nontrivial dependence on the breaking scale of
the Peccei-Quinn symmetry.