• Journal of Korean Society of Forest Science
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• v.113 no.2
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• pp.164-169
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• 2024

In South Korea, most felling operations involve the use of chainsaws due to steep and rough terrains. This felling technique is responsible for approximately 80% of all fatalities mainly due to unpredictable felling directions. Therefore, readjust monitorised felling is imperative to improve safety in different working conditions. This study examined the effect of wedging on felling direction error and productivity during felling operations. When wedging was applied, a felling direction error within 22° and a productivity of 0.63 m³/min were obtained. These results show a decrease in mean directional error and a dimish in productivity. Thus, although wedging reduces productivity, it is a necessary strategy to improve safety.

• Journal of Korean Society of Forest Science
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• v.105 no.4
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• pp.441-448
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• 2016

The purpose of this study was to broaden our knowledge on the productivity and costs of felling operation in three different harvesting methods(whole tree, tree-length and cut-to-length). Felling was conducted in three different harvesting methods with two workers who have different work experiences. Worker A and B have had felling experiences for about 5 years and 15 years, respectively. Felling productivity in whole tree method was $10.3m^3/SMH$ for worker A and $12.7m^3/SMH$ for worker B. Felling costs for worker A and B were $2,066won/m^3$ and $2,201won/m^3$, respectively. Although felling productivity of worker B in whole tree method was higher than worker A, felling costs of worker A were similar to worker B because the wage of worker B was more expensive than the wage of worker A (p>0.05). In tree-length method, felling cost of worker B were cheaper than that of worker A. Felling productivity and cost in tree-length method were $2.2m^3/SMH$ and $9,890won/m^3$ for worker A and $3.3m^3/SMH$ and $8,459won/m^3$ for worker B, respectively (p<0.05). In cut-to-length method, felling productivity and cost were $2.3m^3/SMH$ and $9,584won/m^3$ for worker A and $3.0m^3/SMH$ and $9,395won/m^3$ for worker B, respectively. Felling productivity of worker B was higher than that of worker A(p>0.05). Our preliminary results found that harvesting methods and worker's experiences highly affect on the productivity and costs of felling operations. These results should be useful for forest managers when planning cost-effective harvesting operations.

• Journal of Forest and Environmental Science
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• v.33 no.2
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• pp.147-153
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• 2017

The purpose of this study was to examine productivity and cost of tree-length harvesting using cable yarding system in a larch (Larix leptolepis) clear-cutting stand located in Pyeongchang-gun, Gangwon-do. We used tree-length harvesting method using cable yarding system with a tower yarder HAM300. The productivity was $17.6m^3/hr$ for felling, $12.4m^3/hr$ for delimbing, $4.2m^3/hr$ for yarding, and $8.1m^3/hr$ for processing. The total cost of the harvesting system was $48,381won/m^3$, which was majorly composed of yarding operation cost, at $40,169won/m^3$ (79.3%), while felling had the lowest cost at $1,154won/m^3$ (4.1%). Major factors affecting felling and processing productivity was tree volume and the number and thickness of branches for delimbing productivity. In addition, we suggest that training and education for machine operators were critical to improve yarding productivity.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.107-112
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• 2014

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 $won/m^3$.

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.451-457
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• 2009

This study was conducted to evaluate the felling productivity by chain saw in thinning operation of Korean pine (Pinus koraiensis) stands. Time study data were collected from 4 thinning site in Korean pine stands. This study derived a regression model to estimate the average felling cycle time for evaluating the productivity in felling, which was used to analyze the felling productivity by thinning period. In the study sites, the average felling cycle time per a tree was 463 sec/cycle and the productivity was $2.26m^3/hr$. Thinning period in Korean pine is divided into three groups by producing purposes; small-diameter log, medium-diameter log, and large-diameter log. And analyzed working time and productivity from thinning period fixed by producing purposes. For the small-diameter log producing purpose estimated to be thinning period operated once when the mean DBH was 16 cm and its productivity was $8.94m^3/man{\cdot}day$. For the medium-diameter and large-diameter log producing purposes, thinning period was twice and three times when the mean DBH of the 1st and 2nd thinning period was 16 cm and 21 cm, and its productivity was $9.06m^3/man{\cdot}day$ and $10.86m^3/man{\cdot}day$. The 30 cm in DBH and $15.12m^3/man{\cdot}day$ in productivity was operated 3rd thinning for the large-diameter log producing purposes.

• Journal of Korean Society of Forest Science
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• v.111 no.4
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• pp.567-582
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• 2022

Chainsaw use for motor-manual timber harvesting in South Korea is associated with worker safety issues. However, forestry operations such as timber harvesting have already been mechanized to reduce hazards to workers and increase productivity. This study analyzed the productivities and costs of felling and processing, felling and processing using an excavator-based stroke harvester for Pinus rigida and Quercus mongolica stands. To efficiently operate the stroke harvester, we developed a regression equation to estimate the productivities of felling and processing, felling, and processing operations,and we conducted sensitivity analysis of the operation costs using DBH and machine utilization. The felling and processing productivity was 6.53 and 4.02 m³/SMH for P. rigida a nd Q. mongolica, respectively, and the cost was 17,983 and 29,210 won/m³, respectively. The felling productivity for P. rigida a nd Q. mongolica wa s 40.9 and 23.0 m³/SMH, respectively, and the cost was 2,667 and 4,743 won/m³, respectively. The processing productivity for P. rigida and Q. mongolica was 8.25 and 7.75 m³/SMH, respectively, and the cost was 15,296 and 16,283 won/m³, respectively. In the developed regression equation, the DBH, traveling distance, and number of cuttings were found to be important factors (p<0.05). Therefore, it is necessary to construct a DB considering the various conditions and species associated with harvester operations, and further research is needed to increase the accuracy of predicting operation productivity and costs.

• Journal of Forest and Environmental Science
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• v.32 no.2
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• pp.189-195
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• 2016

Logging equipment and method have a major influence on harvesting productivity and cost. This study investigated the productivity and operational costs of tree-length cable yarding system using HAM300, a domestically developed tower yarder. We tested HAM300 for thinning operation in Pinus densiflora stands at Gangreung, Gangwon-do on April, 2014. To assess the productivity we conducted time study for each stage of the operation. When the average time/cycle was examined for each stage of the operation, the longest was for yarding (241 sec), followed by delimbing (237 sec), felling (153 sec), and processing (103 sec). Furthermore, productivity for felling was $8.6m^3/hr$, followed by delimbing ($5.1m^3/hr$), yarding ($3.5m^3/hr$), and processing ($8.1m^3/hr$). The total cost for the tree-length logging system was $58,446won/m^3$, of which the majority was incurred by the yarding cost at $46,217won/m^3$ (79.3%), whereas the lowest cost was for felling at $2,359won/m^3$ (4.1%). We suggest that it is necessary to foster specialized operators and provide training in operating the tower yarder thereby implementing efficient harvesting system resulting from low-cost yarding.

• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.583-592
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• 2014

This study was carried out to investigate the operational time and productivity of logging operation by chain saw, yarder attached on tractor, tower-yarder, mini-truck, mini-forwarder, and chipping operations by mini-chipper, large-chipper in order to develop the efficient logging operation system for utilization of forest-biomass. As a result, the average felling and bucking time using chain saw at the site 1 and 2 was observed to be 182.7 sec/cycle and 518.5 sec/cycle respectively. The average yarding time was 202.5 sec/cycle using yarder attached on tractor and 295.1 sec/cycle using tower-yarder. The average forwarding time was 2,073 sec/cycle using mini-truck and 2,248.4 sec/cycle using mini-forwarder. The operational time of felling and bucking using chain-saw can be delayed according to the direction of fallen trees. The selection of felling direction is very important to yarding operation because the direction between width-yarding and felling are interrelated. Productivity can be improved through educating and training operators in the yarding operations. Mini-forwarder is needed to use because of higher productivity and lower cost than mini-truck. The operational productivity of felling and bucking by chain saw was $66.96m^3/man{\cdot}day$ and $43.86m^3/man{\cdot}day$ at site 1 and 2 respectively. The yarding productivity was $5.68m^3/man{\cdot}day$ by yarder attached on tractor, $10.74m^3/man{\cdot}day$ by tower-yarder. The forwarding productivity was $21.29m^3/man{\cdot}day$ by mini-truck, $28.57m^3/man{\cdot}day$ by mini-forwarder. The chipping productivity was $4.42m^3/man{\cdot}day$ by mini-chipper, $21.87m^3/man{\cdot}day$ by large-chipper.

• Journal of Forest and Environmental Science
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• v.24 no.1
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• pp.1-14
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• 2008

Clearcutting has been the dominant harvesting method in British Columbia (representing 95% of the total area harvested annually). However forest managers are increasingly recommending the use of alternative silvicultural systems and harvest methods, including various types of partial cutting, to meet ecological and social objectives. In this study we compared harvesting productivity and harvesting costs between treatments through detailed and shift level time studies in 300-350 year-old Interior Cedar-Hemlock stands in British Columbia, Canada. Recommendations for improving operational planning/layout and the implementation of clearcut and partial cutting silvicultural systems were made. Harvesting costs varied in the ground-based clearcut treatments from $10.95/$m^3$ - $15.96/$m^3$ and $16.09/$m^3$ - $16.93/$m^3$ in the group selection treatments. The ground-based group retention treatment had a cost of $13.39/$m^3$, while the cable clearcut had a cost of $15.70/$m^3$. An understanding of the traditional and alternative wood products that could be derived from the harvested timber was imperative to increasing the amount of merchantable volume and reducing the corresponding harvesting costs. Stand damage was greatest in the group selection treatments; however, mechanized felling showed an increase in stand damage over manual felling while grapple skidding showed a decrease in skidding damage compared to line skidding.

• Journal of Korean Society of Forest Science
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• v.104 no.2
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• pp.221-229
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• 2015

The purpose of study was to broaden our knowledge on the productivity and cost of thinning operations which has become increasingly practiced in Korea. The thinning operations were conducted in a 40-year old larch (Larix leptolepis) stand, including chainsaw felling and processing at the stump, followed by yarding tree-length logs using a Koller K301-4 tower yarder. The logs were further processed and sorted into 1.8 m and 3.6 m log piles at the landing. We used a standard time study method to evaluate key variables that affect the productivity of thinning operations. The total stump-to-pile operational cost was $41,707won/m^3$. The highest cost activity was the yarding phase which cost $20,083won/m^3$ (48.2% of the total cost), followed by the costs of processing treelength materials into marketable log lengths ($12,143won/m^3$; 29.1%), and then by the costs of sorting/piling the processed logs ($5,039won/m^3$; 12.1%). It was interesting to see that felling and processing trees at the stump had low costs at $1,315won/m^3$ (3.2%) and $3,127won/m^3$ (7.5%), respectively. We used the detailed time study data to develop regression equations which were to predict yarding productivity. Our analysis showed that harvesting system cost was highly sensitive to the number of logs, yarding distance and lateral distance per turn, respectively.