• 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.

• Fire Science and Engineering
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• v.23 no.4
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• pp.32-39
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• 2009

In this study, 18 plots were selected for particular investigation on Gangneung area and Samcheok area and Uljin area, where forest fire was occurred after thinning in 2007. After selection, a relationship between a damage of forest fire and thinning were compared and analyzed. Many factor such as a damaged species, a thinning or non-thinning, a direction of forest fire head, DBH, a height of tree, a mortality of tree, a leeward scorching ratio, a crown damage ratio, a forest tree standing crop density, a crown base height, a leaving of thinning slash, a location of plot (GPS), elevation, an aspect of slope, an angle of slope, and a topography were measured. Therefore, we analyzed a relationship with forest fire. In the result of this analysis, it was founded that the leeward scorching ratio was 24.7% on thinning area whereas 60.2% on non-thinning area. Subsequently, leeward scorching ratio on thinning area was increased by about 35.5% more than on non-thinning area. In the result of analysis about tree species, a forest of pine tree was more damaged than forest of oak tree. The mortality of tree was increased by about 41.4% on non-thinning area. When stands were close to thinning slashes, these were more damaged by 10${\sim}$20% than other stands for increasing of amount of a combustion material. Especially, as potential of re-ignition increased for more cumulated thinning slash, it will be more important to require a method for a periodical removing or practical utilization of slash.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.321-324
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• 2008

Forest fire danger rate of thinning area was lower than that of non thinning area, because height rate of leewardside in burned stem of tree, damage rate of crown and mortality of tree in thinning area were 30.8%, 37% and 48.4% lower than that in non-thinning area, respectively. Intensity of forest fire varied depending upon topographical condition up slope, down slope, aspect, location as well as species, breast height diameter and forest tree density. Especially, a mountaintop area was burned down when forest fire was spread to up slope ridge of mountain.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.223-230
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• 2007

Nowaday, for the promotion of producing forest trees, production of excellent timbers, and build-up of public forest area, it is on the increase of the thinning-forest for artificial forest, natural forest, eco-friendly forest, and the forest for development and improvement of forest resources nationwide. Even though the thinning-forest is applied around 180,000ha every year, the quantity of collected/used products is only 18,000ha $(240,000m^3)$ which is 10% of the whole thinning-forest area. Meanwhile, some reports represent that the left products after thinning-forest might increase the severity of forest fire and the waste of resources. Therefore, this study focused on the analysis of correlation between the accumulated products after thinning-forest and forest fire, and providing a preparation plan for the forest fire.

• Fire Science and Engineering
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• v.21 no.4
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• pp.52-58
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• 2007

The effect of stand-growing-stock characteristics of thinning area and non-thinning area on forest fire was studied in this work. 14 spots were selected from 3 counties such as Yangyang, Injae, and Gapyeong and on-the-spot investigations were performed to evaluate the effect of forest fire. The stand-growing-stock characteristics on the spots were analyzed through the height of tree, breast height diameter, clear length, mortality of branch, forest tree standing crop density, degree of closure, and shrub and grass cover degree. The relation between forest fire and the risk of spread of forest fire were analyzed from the analysis of the stand-growing-stock characteristics. It is considered from this work that the possibility of forest fire is decreased on the thinning area compared to the non-thinning area because of higher clearlength, lower number of tree, lower mortality of branch and higher shrub and grass cover degree.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.17-24
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• 2008

Elbows with various shapes of local wall thinning were numerically analyzed by finite element method to get load-displacement curves and the maximum loads. Results were compared with the experimental data obtained by another study. Elastic-plastic analysis were carried out under the combined loading conditions of internal pressure and in-plane bending loads. Two types of bending loads were considered such as elbow opening mode and elbow closing mode. Also, two different wall thinning geometries were modeled. Wall thinning area located extrados or intrados of elbow inner surface was considered. Longitudinal and circumferential lengths of the thinning area and the thinned thickness were varied for analysis. The results showed that the maximum load of the wall-thinned elbow decreased with increasing of the circumferential thinning length and the thinned thickness in both of extrados and intrados thinning locations in both loading types. The maximum load obtained by the analysis were in good agreement with the experimentally measured maximum load with the same wall thinning type and dimensions. This supports accuracy of the analysis results obtained in this study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.5 s.248
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• pp.533-542
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• 2006

In order to assess the integrity of pipes with local thinning area, the plastic strain as well as the elastic strain at the root of thinned region are required particularly when fluctuating load is applied to the pipe. For estimating elastic-plastic strain at local wall thinning area in a straight pipe under tensile load, an estimation model with idealized fully circumferential constant depth wall thinning area is proposed. Based on the compatibility and equilibrium equations a nonlinear estimation equation, from which local elastic-plastic strain can be determined as a function of pipe/defect geometry, material and the applied strain was derived. Estimation results are compared with those from detailed elastic-plastic finite element analysis, which shows good agreements. Noting that practical wall thinning in nuclear piping has not only a circular shape but also a finite circumferential length, the proposed solution for the ideal geometry is extended based on two-dimensional and three-dimensional numerical analysis of pipes with circular wall thinning.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.1
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• pp.27-34
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• 2011

The objective of this study is to classify the geometry of wall-thinning defect that causes a circumferential crack in the pipe elbows subjected to internal pressure. For this objective, first of all a criterion to determine the occurrence of circumferential cracking at wall-thinned area was developed based on finite element simulation for burst tests of pipe elbow specimens that showed axial and circumferential cracking at wall-thinned area. In addition, parametric finite element analysis including various wall-thinning geometries, locations, and pipe geometries was conducted and the wall-thinning geometries that initiate circumferential crack were determined by applying the criterion to the results of parametric analysis. It showed that the circumferential crack occurs at wall-thinning defect, which has a deep, wide, and short geometry. Also, it is indicated that the pipe elbows with larger radius to thickness ratio are more susceptible to circumferential cracking at wall-thinned area.

• Archives of Plastic Surgery
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• v.45 no.4
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• pp.298-303
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• 2018

Flap thinning is a procedure for making a thick flap thinner. This procedure does more than simply fill in the defected area, and it is better for reconstructing the area both functionally and aesthetically. However, because flap thinning is a rather blind procedure, it may have harmful effects on flap vascularity. Therefore, the vasculature of a flap must be understood before performing flap thinning. This paper analyzes the basic anatomy underlying flap thinning based on the previous anatomic study that categorized flaps into 6 types by their vascular structures. This paper also reviews specific studies of frequently practiced flap procedures (deep inferior epigastric artery perforator flap, thoracodorsal artery perforator flap, and anterolateral thigh flap) and presents important precautions for flap thinning procedures. Finally, this paper briefly examines the axiality of the subdermal plexus, which needs to be taken into account when performing flap thinning.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.217-222
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• 2007

Since 1973, we attain a successful achievement of nation-wide afforestation such as a thick forest and heaped-up leaves. However, the higher of the formation density in forest, the more dangerous to be a large-scale forest fire whenever fire occurs. According to the type of forest in the country, 42% of the forest is occupied by conifer forest that are highly flammable, and the distribution of forest age is in a transition period from immature forest to mature one. And the structure is too weak to the forest fire for the occurrence and spread because there are too many scrub and shrub trees in the forest. As a matter of course, it is on the increase of the thinning-forest that can shift the forest structure from a weak on forest fire to a strong one nowaday. In other words, thinning-forest has primary purposes such as the promotion of producing forest trees, production of excellent timbers, and build-up of public forest area. Furthermore, in some reports, the reduction of ladder fuel by eliminating the vertical/horizontal fuel in a forest and ensuring spaces in the forest can decrease the occurrence of forest fire and the risk of spread of burning as by-effect. Therefore, this study is designed to clarify the relation with the risk of forest fire by an on-spat-investigation of the characteristics of forest composition on the thinning and the non-thinning area.