  We study the effects of the bulk motion of X-ray flares on the shape and
equivalent width of the iron Kalpha line from an untruncated cold disk around a
Kerr black hole using fully relativistic calculations. The flares are located
above a cold accretion disk -- either on or off the rotation axis. For on- or
off-axis flares, the upward/outward bulk motion causes a reduction of the iron
Kalpha line width. To a distant observer with a low inclination angle (\theta_o
\simlt 30deg.), larger upward/outward bulk velocities decrease the extension of
the red wing, with little change in the location of the blue `edge'. In
contrast, an observer at a large inclination angle (e.g. \theta_o=60deg.) sees
both the red wing and the blue `edge' change with the bulk velocity. The
equivalent width of the iron Kalpha line decreases rapidly with increasing bulk
velocity of flares. However, the `narrower' line profiles observed in some
objects (e.g. IC4329A and NGC4593) are difficult to produce using the
out-flowing magnetic flare model with an appropriate equivalent width unless
the X-ray emission is concentrated in an outer region with a radius of several
tens of r_g=GM/c^2 or more. An important result is that the iron Kalpha line
intensity is found to be constant even though the continuum flux varies
significantly, which is true for out-flowing magnetic flares with different
bulk velocities but similar intrinsic luminosities when located close to the
central black hole. We find that fluctuations in the bulk velocities of
out-flowing low-height flares located at the inner region (r\simlt 15r_g) can
account for a constant iron Kalpha line and significant continuum variation as
observered in MCG-6-30-15 and NGC5548. (Abridged)
