Table 2. Cost factors and assumptions used for operation cost analysis.

Cost factor		Operation machine
		Extraction	Chipping		Screening
		Excavator with wood grapple	Forestry tractor	Drum type chipper	Rotary screen	Excavator with bucket loader
Price (won)	(P)	57,700,000	247,500,000	246,000,000	126,000,000	130,000,000
Endurance perioda (years)	(N)	7	10	5	10	7
Economic life (hour)	(H)	9,744	13,920	6,960	13,920	9,744
Annual operation timeb (hour)	(J)	1,392	1,392	1,392	1,392	1,392
Fuel consumption (liter/hour)	(c)	5.0	28.5	-	4.4	8.0
Coefficient of repair and maintenance	(r)	0.8	0.8	0.8	0.9	0.8
Coefficient of lube oil	(l)	0.4	0.4	0.4	0.2	0.4
Interest rate (%/year)	(i)	10	10	10	10	10
Depreciation (won/hour)	P/H or P(N·H)	5,922	17,780	35,345	9,052	13,342
Interest expense (won/hour)	0.5·P·i·0.01/J	2,073	8,890	8,836	4,526	4,670
Costs of repair and maintenance (won/hour)	P/H·r	4,737	14,224	28,276	8,147	10,673
Fuel costc (won/hour)	c·l·(1+0.1)	9,219	52,548	-	8,113	14,750
Other cost (won/hour, Insurance, storage fee etc.)	-	83	249	495	127	187
Sub total	-	22,033	93,692	72,952	29,964	43,622
Labor costd (won/hour, 50% Inclusion incidental expense)	-	47,843	47,843	-	-	47,843
Total machine cost (won/hour, Inclusion labor cost)	-	69,877	141,535	72,952	29,964	91,465
		214,487		121,428

174 day × 8 hour=1,392 hours (Korea Forest Service, 2012)
Endurance period (Miyata, 1980; Woo et al., 1997; Brinker et al., 2002)
Diesel : 1,317 won/liters in 2021, South Korea (Korea National Oil Corporation, 2021)
Standard of labor cost: machine operator (212,637 won/day) (Construction Association of Korea, 2021)