The method 2, wherein {HEAD ~ the width} of the opening portion of {TAIL ~ the core partition} w is changeable 
The method 2 , wherein { HEAD ~ the width } of the opening portion of { TAIL ~ the core partition } w is changeable
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH