• Journal of Forest and Environmental Science
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• v.39 no.4
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• pp.203-212
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• 2023

Directional felling is a felling method practised by the Forestry Department in Peninsular Malaysia as prescribed in Field Work Manual (1997) for Selective Management Systems (SMS) in forest harvesting. Determining the direction of tree felling in Peninsular Malaysia is conducted during the pre-felling inventory 1 to 2 years before the felling operation. This study aimed to predict and analyze the direction of tree felling using the vector-based path distance back link method in Geographic Information Systems (GIS) and compare it with the felling direction observed on the ground. The study area is at Balah Forest Reserve, Kelantan, Peninsular Malaysia. A Path Distance Back Link (spatial analyst) function in ArcGIS Pro 3.0 was used in predicting tree felling direction. Meanwhile, a binary classification was used to compare the felling direction estimated using GIS and the tree felling direction observed on the ground. Results revealed that 61.3% of 31 trees predicted using the vector-based projection method were similar to the felling direction observed on the ground. It is important to note that dynamic changes of natural constraints might occur in the middle of tree felling operation, such as weather problems, wind speed, and unpredicted tree falling direction.

• 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 Korean Society of Forest Science
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• v.110 no.2
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• pp.210-216
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• 2021

Musculoskeletal disorders affect workers' safety in most industries, and forest operations are classified as a musculoskeletal burden according to the Occupational Safety and Health Act in South Korea. In particular, felling and delimbing operations are mainly conducted by manpower, and then, it is necessary to evaluate ergonomic risk assessment for safety of felling and delimbing workers. Three ergonomic risk assessment methods, such as Ovako Working posture Analysis System (OWAS), Rapid Upper Limb Assessment (RULA), and Rapid Entire Body Assessment (REBA), are available for assessing exposure to risk factors associated with timber harvesting operations. Here, three ergonomic risk assessment methods were applied to examine ergonomic risk assessments in chainsaw felling and delimbing operations. Additionally, exposure to risk factors in each method was analyzed to propose an optimal working posture in felling and delimbing operations. The risk levels of these operations were evaluated to be highest in the RULA method, followed by the OWAS and REBA methods, and most of the exposed working postures were examined with a low-risk level of two and three without requiring any immediate working posture changes. However, two significant working postures, including the bending posture of the waist and leg in felling operation and standing posture on the fallen trees in delimbing operation, were assessed as the high-risk level and needed immediate working posture changes. Low-risk work levels were examined in the squatting posture for felling operation and the straightened posture of the waist and leg for delimbing operation. Moreover, the slope in felling operation and the tree height in delimbing operation significantly affected risk level assessment of working posture. Therefore, our study supports that felling and delimbing workers must operate with low-risk working postures for safety.

• Tunnel and Underground Space
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• v.17 no.5
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• pp.381-388
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• 2007

The regular RC structures have been transformed into irregular RC structures by alternate load of RC structures during explosive demolition. Numerical simulation programs have contributed to a better understanding of large displacement collapse behavior during explosive demolition, but there remain a number of problems which need to be solved. In this study, the 1/5 scaled 1, 3 and 5 stories RC structures were designed and fabricated. To consider the collapse possibility of upper dead load, fabricated RC structures were demolished by means of felling method. To observe the collapse behavior of the RC structures during felling, displacement of X-direction (or horizontal), displacement of Z-direction (or vertical) md relative displacement angle from respective RC structures were analyzed. Finally explosive demolition on the scaled RC structures using felling method are carried out, collapse behavior by felling method is affected by upper dead load of scaled RC structures. Displacement of X and Z direction increases gradually to respective 67ms and 300ms after blasting. It is confirmed that initial collapse velocity due to alternate load has a higher 3 stories RC structures than 5 stories.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.593-601
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• 2020

This study was conducted to analyze the physical strain with heart rate monitor in timber harvesting operations in order to reduce occupational accidents. The timber harvesting activities are manual cutting(felling, limbing and bucking) with a chainsaw and extraction by cable yarder. The study took place on Japanese larch stand. The average height was 26m and average diameter at breast height(DBH) was 3 7cm. The havest unit was gentle slope to steep slope. Results showed that the heart rate increases for chocking, felling, limbing and bucking were 94.0%, 87.9%, 84.8% and 56.4% respectively. The rate of Work Load Index was higher in the limbing(61.4%) activity than other activities chocking(55.2%), felling(54.1%) and bucking(32.1%). During 50% working heart rate test it was found that limbing(1.09), chocking(1.05) and felling(1.04) was exposed to high work intensity compared to bucking(0.83). The results showed that maximum acceptable work times(felling, chocking and limbing) were 2.30 hour, 1.85 hour and 1.60 hour respectively. To avoid occupational accidents, timber harvest workers may use a suitable working hour schedule to felling, chocking, limbing.

• Journal of Forest and Environmental Science
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• v.35 no.3
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• pp.197-204
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• 2019

A tree-length harvesting system using the HAM300, which is mounted on a farm tractor prototype machine, have been recently introduced in South Korea for thinning old (>30 years) forests. However, no research has previously been conducted on the characteristics of residual stand damage associated with cable yarding systems on thinning treatment stands in South Korea. Therefore, there were assessed on the degree and quantity of residual stand damage caused by felling and yarding process to broaden the knowledge of residual stand damage on semi-mechanized skyline thinning operations. This study investigated scar size, direction, area, shape type and their distribution on the residual stand damage caused by felling and yarding operations. Damage to residual trees was generated for 7.4% and 6.9% of residual trees in felling and yarding operations, respectively. Damaged direction of scars was located in front-side (38.9%) and up-side (34.7%) for felling operations while the highest scar damage was found on down-side (44.6%) for yarding operations. Scar heights of felling damage were higher than those of yarding damage. In yarding operation, the most of the scars was located within l0m from the center of the skyline corridor. These results should be useful information for forest managers and landowners to reduce residual stand damages and retain valuable timber volume from thinning treatments.

• Journal of Korean Society of Forest Science
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• v.109 no.4
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• pp.504-511
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• 2020

This study estimated planned felling volumes to set targets for management planning of nationwide country-owned forests. Estimates were made using timber harvest prediction methods that use probability density functions, including area weighting (AW), area ratio weighting (ARW), and sample area change ratio weighting (SCRW). Country-owned forest areas in 2010 and 2015 were used to estimate planned felling volumes, as shown in basic forest statistics, and calculations were made assuming that the felling areas were the changes in the forest area over the 5-year period. For the age classes of V-VI, the average felling ages for AW, ARW, and SCRW were 5.41, 5.56, and 5.37, respectively, and the felling areas were 594,462, 586,704, and 580,852 ha, respectively, with ARW reaching closest to the actual changes. The actual changes in the areas and chi-squared test results were most stable with the SCRW method. This study showed that SCRW was more adequate than AW and ARW as a method to predict timber harvests for forest management planning.

• Journal of the Korea Furniture Society
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• v.21 no.1
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• pp.17-25
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• 2010

Three buildings -Jibokjae, Hyubgildang and Palujung- are connected each other and consist of a library and reception complex for royal kings at Kyungbok Palace in Seoul. Jibokjae and Hyubgildang were known to have been moved from Changdok Palace in A.D. 1891. No construction records have been known for Palujung. In 2004, during repair of three buildings, a dendrochronological analysis was conducted to examine their building histories. We took 67 wood samples for dendrochronological analysis; 20 from Jibokjae, 37 Hyubgildang and 10 Palujung, respectively. The results showed that the felling dates of Jibokjae and Hyubgildang woods were A.D. 1877-1879/1880, indicating original construction of two buildings at early 1880s. Felling dates of Palujung were 1886-1889/1890, those of roof filling timbers 1890 and the connection part between Hyubgildang and Jibokjae 1886, confirming 1891's movement of Hyubgildang and Jibokjae and adding a new building, Palujung.

• Journal of Korean Society of Forest Science
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• v.60 no.1
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• pp.17-23
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• 1983

Total 83model forest owners in Korea were investigated to find out the relationship between their attitudes toward tree felling (or propensity to felling) and selected six independent variables, i.e, owner's age(X1), educational level(X2), forest land area (X3), socioeconomic status (X4), communication (X5) and sociopsychological factor(X6). The dependent variable was measured by Liken attitude scale, and analyzed by multiple regression. Major findings of the study are summarized as follows: 1) The degree of the propensity of felling is relatively high. The communication and sociopsychological variables are negatively, but education level is positively related to the dependent variable. 2) The multiple correlation coefficient between felling-attitude score and six independent variables is 0.5322. Of the variance of this sttitude score, about 13 percent can be explained by communication variable, 6 percent by sociopsychological variable and other 6 percent by age variable. 3) The model owners' attitudes toward felling are positively correlated with there sources of communication variable, i.e. personal contact, social participation and mass media contact. The multiple correlation coefficient between felling-attitude score and three sources of communication variable is 0.4049. This means that 16 percent of the variance of the attitude score can be explained by three sources of communication, that is, 9 percent by personal contact, 5 percent by social participation and 3 percent by mass media. 4) The fatalistic, untrustful and non-ambitious personalities were positively, but conservative personality negatively related to the propensity to tree felling. The multiple correlation coefficient between seven different personalities and the dependent variable is 0.5461. Of the variance of the dependent variable, 11 percent can be explained by untrustful personality, and other 11 percent by nonambitious personality.