  We report results of numerical relativity simulations for {\it new} 26
non-spinning binary neutron star systems with 6 grid resolutions using an
adaptive mesh refinement numerical re\ lativity code {\tt SACRA-MPI}. The
finest grid spacing is $\approx 64$--$85$ m, depending on the systems. First,
we derive long-term high-precision inspiral gravitational waveforms and show
that the accumulated gravitational-wave phase error due to the finite grid
resolution is less than $0.5$ rad during more than $200$ rad phase evolution
irrespective of the systems. We also find that the gravitational-wave phase
error for a binary system with a tabulated equation of state (EOS) is
comparable to that for a piecewise polytropic EOS. Then we validate the SACRA
inspiral gravitational waveform template, which will be used to extract tidal
deformability from gravitational wave observation, and find that accuracy of \
our waveform modeling is $\lesssim 0.1$ rad in the gravitational-wave phase and
$\lesssim 20 \%$ in the gravitational-wave amplitude up to the
gravitational-wave frequency $1000$ Hz.\
  Finally, we calibrate the proposed universal relations between a post-merger
gravitational wave signal and tidal deformability/neutron star radius in the
literature and show that th\ ey suffer from systematics and many relations
proposed as universal are not very universal. Improved fitting formulae are
also proposed.
