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Purpose: This study was conducted to classify the energy efficiency of 131 tractor models tested during from 2006 to 2010 in Korea. Methods: Four sub-indexes were developed using the fuel consumptions at 60% and 90% of rated speed with partial loads and at pull speeds of 3.0 km/h and 7.5 km/h with maximum drawbar pull. Weighting factors of the sub-indexes were also considered to reflect the characteristics of tractor's actual working hours in Korea. Four sub-indexes were integrated into a classification index. Using the developed classification index, a five-classification system was made on the basis of normal distribution of tractors over the classification range

Abstract.The burning of fossil fuels and the resulting CO2 emissions are related to climate change and global warming. In order to help meet international goals of preventing irreversible climate change, South Korea must reduce its gross CO2 emission level from its 2015 level of 680 Mt. Knowing current sources of CO2 productions is essential for accomplishing this reduction. This study calculated the level of CO2 emissions by agricultural tractors, heaters, and dryers which are accounted for consuming 88.6% of the tax-free fuels allocated for agricultural use in South Korea. After the amount of fuel and electricity consumed by each machine was determined, CO2 emissions from each were estimated using the combustion equations. The total annual amount of CO2 emissions produced by these agricultural machines was estimated to be 4,334.2 kt which is less than 1% of the gross CO2 emissions in South Korea in 2015. Keywords: Agricultural dryer, Agricultural heater, Agricultural tractor, CO2 emissions.

Abstract. This study involved performing an economic analysis on agricultural tractors classified based on energy efficiency grades using the energy efficiency index. Specifically, 131 models of agricultural tractors commonly used between 2006 and 2010 in South Korea were classified into five categories. The relationship between energy efficiency and economic value was evaluated by a numerical method, and a method of predicting cost and fuel savings based on energy efficiency was developed. Grades of energy efficiency labeled from 1–5 were assumed in order to calculate annual fuel and cost savings. The results indicated that the use of the proposed method resulted in fuel and cost savings given an upgrade from the 5th level of energy efficiency to the 1st level and indicated subsequent improvements with each grade level. This method was applied to data from the year 2008, and total fuel and cost savings were obtained. This indicated that fuel and cost savings in an arbitrary year could be predicted using the proposed method and assuming data from an arbitrary year. Keywords: Agricultural tractors, Economic analysis, Energy efficiency classification grade, Energy efficiency index.