By using the present invention, {HEAD ~ the power factor} is held constant by {TAIL ~ a closed loop feedback} 
is held constant by
By using the present invention , { HEAD ~ the power factor } is held constant by { TAIL ~ a closed loop feedback }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL