Table 3. Productivity and cost of wood chips production and processing from logging residues by harvesting and processing system.

System		Extractiona (Excavator with wood grapple)	Forwarding (Excavator with wood grapple+Forwarder)	Transportationd (Excavator with wood grapple+Truck)	Chipping (Chipper)	Screening (Screening machine)	Total
Cut-to-length	productivity (Gwt/SMH)	5.0	7.3	14.5	11.6	7.7	1.6g
	cost (won/Gwt)	13,975	16,905b	24,725	18,490e	15,770	89,865
	machine utilization rate(%)	91.9	36.0	-	100.0	100.0	-
Whole-tree	productivity (Gwt/SMH)	-	7.1	14.5	14.3	7.7	2.9g
	cost (won/Gwt)	-	17,480c	24,725	14,999f	15,770	72,974
	machine utilization rate(%)	-	44.4	-	100.0	100.0	-

Extraction ratio of logging residues : 45.6%,
forwarding distance : less than 1.0 km,
Forwarding distance : less than 1.8 km,
Transportation distance : 100 km (25ton truck)[Cho. 2019],
Moisture content of chipping operation : 22.9%, 34.1%,
System productivity (harmonic mean)