• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.15-21
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• 2006

The objective of this research is to develop the technique for carbonization of wood pellet and analyze a possibility for the utilization of carbonized wood pellet. The properties of wood pellet charcoals, such as density, yield, elemental composition, higher heating value, and methyleneblue adsorption, were analyzed. Wood pellet was made of sawdust of Hyunsasi-poplar, Japanese larch, Korean pine, Korean red pine, and Jolcharn-oak (serrate oak), respectively. The high density charcoal ($0.5{\sim}0.7g/cm^3$) was yielded from densified wood pellet. The carbon contents and calorific values of wood pellet charcoals were increased with the increase of carbonization temperature. The methyleneblue adsorptivity of wood pellet charcoal was similar to that of wood charcoal.

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.101-111
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• 2014

In this study the effect of heartwood-coating (HCO), vapor-dam (VD), bark-remaining (BR) and bark-remaining-coating (BRC) treatments on the air circulating oven-drying characteristics of Japanese larch hollowed round-post was evaluated. The drying times of the hollowed round-posts for control, VD, HCO and BR specimens were 72, 168, 204 and 240 hours, respectively, from the initial MC to about 8% MC, which was recommended as the indoor in-use MC. The temperature in the hole of the VD specimen was lower than that of wood and the difference between air temperature in the hole and wood temperature became large during drying period. The vapor pressure of air in the hole was higher than that of inside wood for all specimens except VD specimen. The surface checks on all specimens were observed in increasing order of BR, BRC, UC, HCO and VD specimens.

• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.61-66
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• 1993

24mm-thick specimens from three species of plantation-grown softwood were press dried under two platen pressures of 1.75kgf/$cm^2$ and 3.50kgf/$cm^2$ to obtain drying information regarding to drying rate, thickness shrinkage and drying defects. The influence of platen pressure on drying fare in range of moisture content (30 to 10 percent) increased for pitch pine and larch, but reduced for korean white pine at higher pressure. Thickness shrinkage was increased at the higher pressure, and estimated thickness shrinkage at final MC of 10 percent became unrealistically greater for specimens containing higher final moisture content under the great influence of compressive strain. The effects of pressure on the amount of surface checks and honeycombing were different from species used. These species should have applied lower temperature than 177$^{\circ}C$ in this study to reduce surface checks and honeycombing.

• Journal of Forest and Environmental Science
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• v.27 no.2
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• pp.113-118
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• 2011

This study was carried out to analyze annual diameter growth characteristics for major 11 tree species using the data for Gangwon province of the National Forest Resources Inventory in 2007. The annual diameter growth of coniferous species was 5.02 mm, 4.70 mm, and 3.90 mm in Korean white pine, Japanese larch, and Korean red pine, respectively. In growths of the deciduous trees, dogwood, basswood, and cork oak had 3.55 mm, 3.48 mm and 3.01 mm, respectively. Average of the annual diameter growths for all species was 3.38 mm. The relationship between diameter growth and age class showed that the growth rate decreased for all species as age increased. The age class II had the highest annual diameter rate. In relation of the stand density(trees per hectare) and diameter growth, the diameter growth tended to decrease as the stand density increased for most species, especially Korean white pine, cork oak, and basswood. Finally age had the highest value in the correlation coefficients between measurement factor and growth rate regardless of species.

• Journal of the Korean Wood Science and Technology
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• v.39 no.2
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• pp.172-178
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• 2011

Three different finger-jointed lumbers which have different geometric features and adhesives were manufactured and studied in this study. Larch and pitch pine lumbers with and without preservative treatment were used. Bending MOE was measured as the preliminary investigation for grouping the specimen. After the finger, bending MOE of two wood species without preservative treatment shows over 97% property of the control group. The tensile modulus also shows almost same property after the finger joint. And it is found out that the preservative treatment induce little effect on bending and tensile MOE. Based on this result, high performance of examined finger-jointed lumber can be found out. However, tensile strength decreased around 20% which would be induced by the crack along the root of the finger which is formed near the edge during manufacturing stage. And finger-jointed lumber with preservative treatment even shows higher decrement of the tensile strength with higher wooden part failure mode.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.20-29
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• 1999

Temperature has important effect on mechanical properties of wood. These effect needs to be understood and taken into account in the structural use of wood. Furthermore, the effect of cooling after exposing to high temperature must be explained. In this study, the effect of temperature, exposure time, specific gravity, and cooling on bending properties were investigated. The boundary temperatures at which bending MOE and MOR reduced rapidly were approximately $200^{\circ}C$ and $150^{\circ}C$, respectively. This boundary temperature was nearly constant with independence of species(specific gravity), exposure time, and cooling. Above the boundary temperature, the effect of exposure time was increased with temperature and the reduction of bending MOE and MOR for Japanese Larch with relatively higher specific gravity was smaller than that of Hem-fir. The recovery of bending MOE and MOR after cooling was also more significant above the boundary temperature than below. The degree of cooling effect was larger for MOR than MOE. Consequently, bending properties of wood in elevated temperatures should be considered in terms of the boundary temperature, $200^{\circ}C$ for bending MOE, $150^{\circ}C$ for MOR, and these boundary temperatures must be considered an important factor. Furthermore, to evaluate the safety of structure, the recovery after cooling should be considered.

• Journal of the Korean Wood Science and Technology
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• v.39 no.5
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• pp.437-443
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• 2011

In Korea, there has been a traditional post and beam wood construction with large roof load. Because a large friction is generated in wooden joint or members, it is important to evaluate the friction between wood members according to wood direction. Because most of studies have been concerned with friction between wood and steel, excluding effect of real area of contact, there are a few studies on the friction between wood members. The object of this study was to evaluate friction or coefficient of friction according to normal force and real area of contact of wood. With Japanese larch (Larix kaempferi) test specimens, five steps of normal force and combinations of test were prepared. Results indicated that normal force had almost no affection on the friction, however there was difference about friction or coefficient of friction according to real contact conditions of wood grain and contact area.

• Journal of the Korean Wood Science and Technology
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• v.37 no.5
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• pp.465-473
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• 2009

Three failure theories were studied to evaluate the wood strength variation with grain slope. Maximum stress theory, Tsai-Hill theory and Hankinson formula were presented to hypothesize the failure of wood according to grain slope to loading direction. Red pine and Japanese larch were used as materials to simulate failure strength prediction with grain slope. Calculation of strength results was that the strength of wood drops rapidly between parallel to grain orientation (0 degree) and 15 degree grain orientation. The strength of wood with grain orientation were somewhat different at small grain angles among failure theories, and this tendency was due to tension and compression distinction, and shear accounting in each theories. For the above 45 degree grain orientation, the predicted failure strength of wood with grain variation were very close in each failure theories and were useful in assessing failure strength of wood. The applicable these theories should be considered that the wood has different behavior in tension and compression, and this lead to different strength at small grain angles in each theories. Furthermore, reconsideration is needed to assess the failure strength of wood at small grain angles in Hankinson formula and further studies are necessary to accounting for shear behavior at small grain angles.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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• pp.261-269
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• 2014

Most areas in Gangwon-do are mountainous regions where causes heavy damages due to landslides. It is important to analyze basic factors influencing the cause of landslides in order to prevent such landslides. For this study, a landslide occurring site is extracted from aerial images taken after the landslide caused by typhoon 'Ewiniar' in Pyeongchang area 2006. Also, the overlay analysis with the topographic, forest, and soil maps in this area is performed using GIS based methods. In addition, the topographic, forest, and soil characteristics relating to the landslide factors are analyzed. As a result, large numbers of landslides occurred at a slope angle of $20^{\circ}-40^{\circ}$. In the case of the forest factors, there are close relationships between the artificial pine and larch forests and the frequency of landslides. The low forest density represents a weakness in landslides. In the case of the soil factors, a higher level in the surface soil with a type of sandy loam soil, a higher gravel content in subsoil, and a higher degree of acid rocks in soil parent materials cause higher frequencies in landslides.

• Journal of Korean Society of Forest Science
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• v.71 no.1
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• pp.27-32
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• 1985

Individual tree growth in a given stand is considerably affected by its neighbouring trees or surrounding density. This trend is appeared more clearly in the unthinned stand. Relationship between growth of individual trees and density around them was analyzed by the use of the angle-summation method(AS method), and then multiple regression equation including variables of center trees and measures of surrounding density by the AS method was given for estimating diameter increment for the last five years and the next few years of center trees.