No abstract

This study has been carried out to investigate the characteristics of pellets manufactured from sawdust, and a mixture of liquid wood-tar and sawdust. Pellets were prepared at room temperature under 2000 kgf/cm 2 using an universal testing machine. The pellets prepared from Q. variabilis wood had slightly higher density than those prepared from P. densiflora wood. The amount of fine particles from Q. variabilis wood pellets was smaller than those from P. densiflora wood. The pellets from P. densiflora wood had higher heating values than those from Q. variabilis wood. The wood pellets manufactured with wood tar showed higher moisture content, density and heating value, but lower fine particles. From the experimental results, it is suggested that wood tar can be used to obtain the higher quality wood pellets.

Tree diameter, topography, and stand accessibility have been major issues to consider when selecting the optimal equipment to extract logs from steep slopes. With an increasing interest using cable logging systems from steep slopes in South Korea, the yarding productivity and cost were evaluated for a small scale cable yarder. A standard time and motions study method were applied for three clearcut units in larch (Larix kaempferi) stands located in Pyeongan, Gogil, and Ungyo in Eastern Gangwon of South Korea. The average yarding productivity and cost were calculated at 5.7 m 3 /scheduled machine hour (SMH) and $27.9/m 3 , respectively. The regression analysis reveals that the mean diameter class was found to have greatly influenced yarding productivity. Among the factors determining the yarding cost, tree volume was found to have the greatest influence, followed by lateral distance and yarding distance. Other factors that may contribute to reducing delay and improving yarding productivity included operational planning (i.e. corridor layout considering topographic conditions), pre-inspection, and post-maintenance/management of the yarder system, and specialized technical training to enhance yarding productivity.

The productivity and cost of clear cutting operations were examined to broaden our knowledge on the harvesting system in a Larix leptolepis stand of Korea. The harvesting system was divided into tree operations which were chainsaw (STIHL MS440) felling, tower yarder (Koller301-4) yarding and harvester (WOODY H50) processing. The average cycle time of felling, yarding and processing were 98 s/cycle, 245 s/cycle and 150 s/cycle. The total stump-to-pile operational productivity was 43.07 m 3 /hr. The highest production activity was the felling 17.93 m 3 /hr, followed by the productivity of processing 15.62 m 3 /hr and then by the productivity of yarding 9.52 m 3 /hr. In addition the total stump-to-pile operational cost was 24,086 won/m 3 . The highest cost activity was the yarding 14,557 won/m 3 (60.4% of the total cost), followed by the costs of processing 8,461 won/m 3 (35.2%) and then by the costs of felling 1,068 won/m 3 .Key Words: Larix leptolepis, harvesting system, harvesting productivity, operational cost

Shallow landslides triggered by heavy rainfall are common phenomena in mountainous areas of temperate monsoon regions. On July 2006 intensive shallow landslides occurred in Jinbu area, Korea triggered by heavy rainfall. An inventory of 1412 shallow landslides was constructed from intensive field works and interpretation of web-based aerial photographs, and all landslides detected were mapped across the study area. The measurements were geometrical properties (landslide length, landslide width, landslide depth) of individual landslides to establish the relationship linking landslide area to landslide volume. The relationship linking landslide area to landslide volume was obtained from the inventory of 930 landslides and is a power law function with a scaling exponent g = 1.02, covers four orders of magnitude of landslide area and landslide volume, and is in reasonable agreement with existing relationships obtained from small scale shallow landslide events. The relationship can be used to estimate the volume of individual landslides with shallow soil depth when the area of landslide is known. However, geological and geomorphological setting should be considered to calculate accurate landslide volume with respect to disaster prevention.