  We construct a realization of the Yangian double DY_\hbar(gl_N) and
DY_\hbar(sl_N) of an arbitrary level k in terms of free boson fields with a
continuous parameter. In the \hbar \to 0 limit this realization becomes the
Wakimoto realization of kac-Moody algebra gl_N and sl_N, respectively. The
vertex operators and the screening currents are also constructed with the same
spirits; the screening currents commute with DY_\hbar(sl_N) modulo total
difference.
