• Journal of agriculture & life science
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• v.53 no.6
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• pp.35-44
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• 2019

The objectives of this study were to identify engineering problems in the design and installation of cable logging operation that affects productivity through case study of actual logging sites, and to analyze associated productivity loss and increased cost. As a result of the study, when the geographic conditions and engineering safety of the site are not sufficiently considered, deflection of the cable line can not be secured. Hourly productivity of the operation decreased to 65% and the logging cost increased by more than two times compared to the productive yarding operation, which lowered overall efficiency of the operation. Thus, it is required to spread filed technologies that minimize unnecessary production cost incurred due to the in-efficient logging operations as well as secure work safety and efficiency to expand cable logging operation throughout the country.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.357-364
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• 1994

In this paper, the characteristics of cable logging systems, of which skyline length is adjustable during operation are discussed from a standpoint of system geometry. Among the cable logging systems, the live skyline is the typical one, of which operation is easy to understand. To analyze the cable logging mechanics of the live skyline, computer models were developed. In developing the computer models, the concept of the live skyline operation was classified into 'true live skyline' and 'live skyline with lift'. The former assumes to adjust skyline length continuously to maintain the skyline clearance over ground constant during inhaul ; the latter assumes to shorten the skyline length only to keep the minimum skyline clearance during inhaul. The computer model was used in investigating the mechanical efficiency and the operational characteristics of the live skyline system. First, the payload capability of live skyline was compared with that of standing skyline. Second, the effect of the change in the log-drag geometry on the payload capability of live skyline was investigated. Finally, the payload capability of live skyline with lift was compared with that of true live skyline as an effort to explain the concepts of true live skyline and live skyline with lift.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.195-206
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• 1993

The purpose of this study is to provide a basis for establishing regional harvesting systems that ist the prerequisites for the forest mechanization. The factors restricting to the forest harvesting and logging methods from topographical aspects are studied for this purpose. Three main harvesting methods studied in this paper are : shortwood method, longwood method and full tree method. This study shows : the shortwood method is suitable for low, the longwood method for medium, the full tree method for high topographical conditions. For the logging methods, the focus of the study is on various ground based logging systems by animalpower, manpower, gravitation, wheeled & crawler vehicle and cable. The factors limiting the coverage of logging operation are slope and logging distance. The cable crane logging methods are classified by logging distance into short distance(to 300 or 400m), middle distance(to 700 or 800m) and long distance cable crane methods (over 700 or 800m). The wheeled vehicle method shows serious damages to forest resources, whereas the logging by log-line of the gravitation logging method and cable crane method tend to minimize such damages. The wheeled & crawler vehicle method also shows difficult to apply in the high slope conditions, whereas cable crane method can be applied to maximum 120% steep slope and uphill conditions.

• Journal of Korean Society of Forest Science
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• v.105 no.2
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• pp.231-237
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• 2016

This research was conducted in order to examine whether the Woodgrab short-wood logging method, most widely used logging method in Korea, is more favorable than other logging methods in terms of productivity and profitability. For the comparative purposes, whole-tree logging methods with cable yarding system using a swing yarder and a tower yarder were evaluated. The productivity and the profitability of the logging operations by the machine types on a L. kaempferi stand were estimated by simulating logging processes based on bucking patterns and the results were compared. As a result, the Woodgrab short-wood logging system showed the most favorable results in terms of skidding productivity and operating cost. On the contrary, the system was the least profitable among the three logging methods. Main reason is that while the system may be beneficial in terms of operation productivity, it is restricted to produce only short logs mainly for low quality raw materials such as pulp, bolts, etc. which are sold at cheap prices.

• Journal of Korean Society of Forest Science
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• v.82 no.1
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• pp.34-43
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• 1993

In this paper, the characteristics of cable logging operations are discussed from a standpoint of mechanics. An example of standing skyline operations is used to illustrate the mechanical principles. Using force and moment boundary conditions, the maximum allowable payload was formulated as a function of slope profile, system geometry and operation options. This formulation includes fundamental equations for log drag and single segment mechanics. The catenary link model is the basic assumption in simulating cable segment stretches. In order to demonstrate the solution procedures of the formulation, a computer model was developed. The model uses Secant algorithm to determine the solution of the complex nonlinear equation set. Finally, the computer model was demonstrated using a hypothetical data set.

• 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.95 no.4
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• pp.495-500
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• 2006

Stability of cable yarding with self-propelled carriage was discussed by theoretical tension calculation and field test. To verify usefulness of theoretical stability evaluation of cable yarding operation, skyline tension and stump anchoring force were measured and compared with theoretical calculation. As results, we know that measured skyline tension was similar to theoretical calculated tension. From these results, overall stability of cable logging operation could be evaluate. The stump anchoring force correlated closely with the stump diameters. The inclination angles that the stumps show the maximum anchoring force were ranged 5-10 degrees. It was conclude that the stumps have lost the function as an anchor when the inclinations was so large that they could be observed.

• 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 the Korean Association of Geographic Information Studies
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• v.6 no.1
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• pp.85-97
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• 2003

This study was aimed at suggest a proper logging method of mountain forest using geographic information system(GIS) based on digital terrain model(DTM) in the National Forest at Mt. Kumsan in Namhae-gun, Gyungsangnam-do, which has about 2,948 ha in area. The areal percentage of 201 to 250m in the elevation was about 15.5%, elevation of 251 to 300m was 14.5%, and 78.75% for higher than 400m. The accumulated areal percentage of below 30% in the gradient was 17.2%, and 81.0% for steeper than 60%. The area for tractor skidding was 17.2%(511.7ha), the area for tractor attached winch skidding was 63.8%(1,896.3ha) and 18.4%(545.5ha) for cable yarding. It is important to choose the proper logging machines for timber harvesting. In general, the selection of logging operation system was affected several major environmental factors like as terrain conditions(slope gradient, slope length) and stand factors. The rate of middle slope gradients in terrain conditions showed higher than that of steep slope gradients in this area. Therefore, it considered that the logging operation system in this area could apply to tractor+winch operating machine according to terrain conditions.