A cell of the outer peripheral side honeycomb unit in contact with the outermost peripheral cell wall thereof has a corner part having a curved surface, where {HEAD ~ the corner part} is on {TAIL ~ the side} contacting the outermost peripheral cell wall 
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A cell of the outer peripheral side honeycomb unit in contact with the outermost peripheral cell wall thereof has a corner part having a curved surface , where { HEAD ~ the corner part } is on { TAIL ~ the side } contacting the outermost peripheral cell wall
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH