• Journal of Forest and Environmental Science
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• v.33 no.1
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• pp.74-77
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• 2017

The purpose of this study is to analyze the effect of thinning intensity on the growth of large diameter trees in Korean white pine (Pinus koraiensis S. et Z.) plantation. Eight thinning plots were analyzed by categorizing into heavy thinning, light thinning, no thinning (control) according to thinning intensity. As a result, average DBH increased more in heavy thinning plots than in light thinning or unthinned plots. The number of large trees (DBH>25 cm) were obviously shown the most in heavy thinning plots. It is considered that heavy thinning is needed for the production of the large diameter trees.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.153-156
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• 2008

Comparative analysis of forest fire danger rating on the forest characteristics of thinning area and non-thinning area on forest fire burnt area was studied in this work. To investigate the effect of thinning slash in forest fire, Gangneung-si Wangsan-myeon, Ulgin-gun Wonnam-Myeon, Samchok-si Gagok-Myeon, in which forest fire broke out, were selected. As a result that investigated forest fire danger ratio between thinning slash and non-thinning slash, leeward scorching ratio(36%), crown damage ratio(29%), mortality of branch at the former are higher than those at the latter, leeward scorching ratio of tree, where thinning slash is around, is 10%-20% higher than that of independent tree. So I estimate that thinning slash has a some effect on the intensity of forest fire. And the result to investigate damage of forest fire according to tree species shows that leeward scorching ratio of conifer is 5% higher than that of non-conifer, and mortality of branch of the former is 19% higher than that of the latter. It is considered that forest fire may affect directly to a tree trunk if it diffuse to piled thinning tree because there was no space between thinning trees and trees. Furthermore, it was found that re-ignition had a chance to occur due to lots of piled thinning trees.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.392-396
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• 2010

This research focused on determining the effectiveness of cluster and/or flower thinning in highbush 'Jersey' blueberry on the yield and fruit quality. The total yield and quality of fruit were compared between thinning methods of control (no thinning), 1/3 cluster thinning, 1/3 cluster thinning + 1/2 flower thinning, 2/3 cluster thinning, and 2/3 cluster thinning + 1/2 flower thinning per each bearing shoot, respectively. Thinning strength significantly affected the yield of bearing shoot and, thus, total yield of control and 1/3 cluster thinning was higher than others. Both cluster and flower thinning, however, significantly affected the fruit growth resulting in the increase of fruit weight, length and width. Even total yield was similar between control and 1/3 cluster thinning, more larger fruit (> 1.6 g) were produced by 1/3 cluster thinning treatment, indicating that flower and/or cluster thinning contributed to the increase of individual fruit growth. Unlike fruit growth, fruit quality was less affected except total soluble solid contents. Total soluble solid level significantly increased in treatments (2/3 cluster thinning, 2/3 cluster thinning + 1/2 flower thinning) with yield decrease. No significant difference in levels of acidity and firmness of fruit was found. Results indicated that fruit growth and total yield of highbush blueberry was more influenced by the thinning strength regardless of cluster or flower than internal quality of fruit such as solid and acid levels.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2119-2129
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• 2020

Flow-accelerated corrosion (FAC), liquid droplet impingement erosion (LDIE), cavitation and flashing can cause continuous wall-thinning in nuclear secondary pipes. In order to prevent pipe rupture events resulting from the wall-thinning, most NPPs (nuclear power plants) implement their management programs, which include periodic thickness inspection using UT (ultrasonic test). Meanwhile, it is well known in field experiences that the thickness measurement errors (or deviations) are often comparable with the amount of thickness reduction. Because of these errors, it is difficult to estimate wall-thinning exactly whether the significant thinning has occurred in the inspected components or not. In the previous study, the authors presented an approximate estimation procedure as the first step for thickness measurement deviations at each inspected component and the statistical & quantitative characteristics of the measurement deviations using plant experience data. In this study, statistical significance was quantified for the current methods used for wall-thinning determination. Also, the authors proposed new estimation procedures for determining local wall-thinning to overcome the weakness of the current methods, in which the proposed procedure is based on analysis of variance (ANOVA) method using subgrouping of measured thinning values at all measurement grids. The new procedures were also quantified for their statistical significance. As the results, it is confirmed that the new methods have better estimation confidence than the methods having used until now.

• Journal of Forest and Environmental Science
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• v.36 no.1
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• pp.17-24
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• 2020

This study aimed to figure out and compare the increment of biomass by thinning intensity focused on the plantation of the two major coniferous species (Larix kaempferi and Pinus koraiensis) of South Korea. The inventory interval was three years under the effects of three types of thinning treatments; control (no thinning), light (20% thinning) and heavy (40% thinning). The results showed standing biomass increment of both species decreased as thinning intensity increased (heavylight>control). Meanwhile, the lowest of on-site biomass changes occurred in the control plot, and the greatest was in the heavy thinning plot because thinning was involved with leaving the felling residual biomass (leaves, branches and roots) on the site. According to the results from this short-term study, unthinned stands is preferable for maximizing standing biomass as well as carbon sequestration. However long-term investigation should be considered in order to see more clear results.

• Journal of the Korean Society of Safety
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• v.21 no.6 s.78
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• pp.14-19
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• 2006

This study performed burst tests using real-scale pipe elbow containing simulated local wall-thinning to evaluate the effects of circumferential thinning angle and bending load on the failure pressure of wall-thinned elbow. The tests were carried out under the loading conditions of internal pressure and combined internal pressure and bending loads. Three circumferential thinning angles, ${\theta}/{\Pi}=0.125,\;0.25,\;0.5$, and different thinning locations, intrados and extrados, were considered. The test results showed that the failure pressure of wall-thinned elbow decreased with increasing circumferential thinning angle for both thinning locations. This tendency is different from that observed in the wall-thinned straight pipe. Also, the failure pressure of intrados wall-thinned elbow was higher than that of extrados wall-thinned elbow with the same thinning depth and equivalent thinning length. In addition, the effect of bending moment on the failure pressure was not obvious.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1295-1302
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• 2003

In order to evaluate a failure behavior of pipe with notch-type wall thinning, the present study performed full-scale pipe tests using the 102mm, Schedule 80 pipe specimen simulated notch- and circular-type thinning defects. The pipe tests were conducted under the conditions of both monotonic and cyclic bending moment at a constant internal pressure of 10 MPa. From the results. of experiment the failure mode, load carrying capacity, deformation ability, and fatigue life of a notch-type wall thinned pipe were investigated, and they were compared with those of a circular-type wall thinned pipe. The failure mode of notched pipe was similar to that of circular-type thinned pipe under the monotonic bending load. Under the cyclic bending load, however, the mode was clearly distinguished with variation in the shape of wall thinning. The load carrying capacity of a pipe containing notch-type wall thinning was about the same or slightly lower than that of a pipe containing circular-type wall thinning when the thinning area was subjected to tensile stress, whereas it was higher than that of a pipe containing circular-type thinning defect when the thinning area was subjected to compressive stress. On the other hand, the deformation ability and fatigue life of a notch-type wall thinned pipe was lower than those of a circular-type wall thinned pipe.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.385-392
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• 2014

The purpose of this study was to determine the effects of plantation thinning on physical and mechanical properties of Larix kaempferi. Tree samples were obtained from unthinned, moderately, heavily thinned plantations where located in Kwangryung forest research stand. The effects of different thinning methods on the bending and parallel to grain compressive strengths of Larix kaempferi were explored. Average latewood ratio with various thinning treatments revealed the trend of unthinning < moderate thinning < heavy thinning treatment. Average annual ring width with various thinning treatments showed the trend of unthinning < moderate thinning or heavy thinning treatment. Average bending and parallel to grain compressive strengths with various thinning treatments revealed the trend of unthinning > moderate thinning > heavy thinning treatment. This indicates that thinning treatment reduces average bending and parallel to grain compressive strength properties.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.165-171
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• 2011

This study was conducted to investigate the effect on pine wilt disease by health-thinning, thinning and sapling tending in red pine forest (Pinus densiflora). As a part of developing forestry control methods for pine wilt disease control. In case of putting in pine sawyer (Monochamus alternatus) with pine wood nematode (Bursaphelenchus xylophilus), the specimen trees in health-thinning, thinning and control treatment were withered more than 50%, although there were not statistically significant differences in treatments. In treatment site, thinning slashes had influenced on the spread of pine wilt disease (experiment 1). In thinning stand of sapling pine, site with thinning slashes had highest mortality (> 90%). There were approximately 10% mortality in the site of carried thinning slashes from case and the site of non-thinning with released M. alternatus (experiment 2). The larvae had not appeared in young tree stump with health-thinning and thinning at April, the current emergence year of M. alternatus, but there were larvae in sapling tree stump with thinning at May, the current emergence year of M. alternatus. In case of stands with infected young and sapling tree by pine wilt disease, there is no effects of on pine wilt disease control by health-thinning, thinning, saplings tending at April and May, the current emergence year of M. alternatus, and leaved thinning slashes had influenced on the spread of pine wilt disease as habitation of M. alternatus.

• Journal of Ecology and Environment
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• v.40 no.1
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• pp.5-11
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• 2016

Background: As the decomposition of lignocellulosic compounds is a rate-limiting stage in the nutrient mineralization from organic matters, elucidation of the changes in soil enzyme activity can provide insight into the nutrient dynamics and ecosystem functioning. The current study aimed to assess the effect of thinning intensities on soil conditions. Un-thinned control, 20 % thinning, and 30 % thinning treatments were applied to a Larix kaempferi forest, and total carbon and nitrogen, total carbon to total nitrogen ratio, extractable nutrients (inorganic nitrogen, phosphorus, calcium, magnesium, potassium), and enzyme activities (acid phosphatase, ${\beta}$-glucosidase, ${\beta}$-xylosidase, ${\beta}$-glucosaminidase) were investigated. Results: Total carbon and nitrogen concentrations were significantly increased in the 30 % thinning treatment, whereas both the 20 and 30 % thinning treatments did not change total carbon to total nitrogen ratio. Inorganic nitrogen and extractable calcium and magnesium concentrations were significantly increased in the 20 % thinning treatment; however, no significant changes were found for extractable phosphorus and potassium concentrations either in the 20 or the 30 % thinning treatment. However, the applied thinning intensities had no significant influences on acid phosphatase, ${\beta}$-glucosidase, ${\beta}$-xylosidase, and ${\beta}$-glucosaminidase activities. Conclusions: These results indicated that thinning can elevate soil organic matter quantity and nutrient availability, and different thinning intensities may affect extractable soil nutrients inconsistently. The results also demonstrated that such inconsistent patterns in extractable nutrient concentrations after thinning might not be fully explained by the shifts in the enzyme-mediated nutrient mineralization.