• Journal of the Korean Wood Science and Technology
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• 제48권4호
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• pp.458-471
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• 2020

Effect of pre-treatment and compression ratio on specific gravity (SG) and dimensional stability improvement of three lesser-used wood species from natural forest area of North Kalimantan Province, Indonesia had been investigated. Hot soaking at 80℃ for 3 hours within 2 and 5% of boron solution was applied as pre-treatment, while compression ratio applied was 20 and 40% from the initial thickness. Densification was conducted using hot pressing machine at 30 kg/㎠ of pressure and 160℃ of temperature for 15 minutes. Specific gravity was measured gravimetrically, while dimensional stability was evaluated through thickness swelling and water absorption as the indicator. Results show that SG of densified wood was influenced by wood species and compression ratio, but not by pre-treatment applied; while dimensional stability was influenced by wood species, compression ratio, and pre-treatment. Specific gravity and water absorption of densified wood was improved significantly. Specific gravity increased 28.86-63.03%, while water absorption decreased 12.80-15.89%. Thickness swelling of 20% densified wood was lower than that of 40% densified wood.

• 한국가구학회지
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• 제21권3호
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• pp.248-252
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• 2010

This study is carried out to introduce the concept of Kagome structure as the new trial for the furniture design and the feasibility of its utilization in furniture industry. Kagome means originally the two dimensional bamboo-basket woven pattern that is composed of interlaced triangles whose lattice points each have four neighboring points, which was used in traditional bamboo craft design like 'Jukbuin(bamboo-wife)'. Its unique truss structure has been widely used by many kinds of the domain of science and engineering in mechanical and architectural industry with some merits, i,e, material utilization efficiency and robust strength. Here we tried to introduce two dimensional and three dimensional form of Kagome which are supposed to be a furniture design elements. Authors think these Kagome design could be realized with domestic lumber of inferior properties. Both of them would be used as a decorative element or mechanical supporter in furniture design.

• Journal of the Korean Wood Science and Technology
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• 제39권5호
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• pp.444-450
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• 2011

The goal of this study is to investigate bending properties of domestic timber. Three representative structural timber from Larix kaempferi, Pinus koraiensis, and Pinus densiflora, in the northeastern South Korea were selected. Visual grading for the timber was conducted based on KFRI notification 2009-01 and the bending strength for the timber was evaluated based on ASTM D 198 bending. The high percentage of grade 1 and 2 for Larix kaempferi shows that the KFRI notification was optimized for this species. The bending strength distributions from Pinus koraiensis and Pinus densiflora were very similar. It could be possible to specify the allowable bending properties of these two Specification using a united species group similar to spruce-pine-fir. Lastly, the bending strength of $120{\times}180mm$ structural members was higher than both existing values in KBC 2009 and design values for timber of imported species described in the NDS. Thus, 120 mm thick domestic softwoods could replace the commercial imported species and the KBC should be modified to provide design values for both timber and dimensional lumber, respectively, like NDS.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.787-796
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• 2017

A low dimensional stability and poor bending strength properties were main problems in particleboard manufacturing. The objective of this research was to evaluate the effect of mixed wood species and urea-formaldehyde (UF) or urea-melamine-formaldehyde (UMF) resins on the physical and mechanical properties of three-layer particleboards. The ratio of face/core/back layer was 1 : 2 : 1. The resin content of 12% for both UF resins and UMF resins (UF/MF = 70/30% w/w) was used. The results of this study showed that the utilization of S.mahagony shaving using both UF and UMF resins caused a decrease in the thickness swelling and water absorption of the boards. Thickness swellings of particleboard made of Sengon/Sengon/Sengon (SSS), Mahogany/Mahogany/Mahogany (MMM), Sengon/Mahogany/Sengon (SMS), and Mahogany/Sengon/Mahogany (MSM) were in the range of 23%, 12~16%, 14~16%, and 13~21%, respectively. The board bonded with UMF resin demonstrated better dimensional stability than that bonded with UF resin alone. Modulus of elasticity (MOE) and modulus of rupture (MOR) of particleboards made of S. mahagony shaving in the surface layer in both MMM and MSM boards were better than those of the SSS and SMS. MOE of MMM and MSM board was in the ranges of 24,000 to $26,000kg.cm^{-2}$ and 18,000 to $21,000kg.cm^{-2}$ respectively. Meanwhile, the MOR of board was in the ranges of 200 to $240kg.cm^{-2}$ and 190 to $228kg.cm^{-2}$, respectively.

• 한국산림과학회지
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• 제77권1호
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• pp.32-42
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• 1988

팔공산(八空山) 남사면(南斜面)에 위치(位置)하는 동화사(桐華寺) 지역(地域) 삼림(森林)의 다목적(多目的) 임업경영(林業經營), 즉 삼림(森林)의 입체적(立體的) 이용(利用)을 위한 기초적(基礎的) 자료(資料)를 수립(樹立)할 목적(目的)으로 ZM학파의 식생분석법에 기초를 둔 풍원(豊源) 및 Pfister의 식생분석법(植生分析法)으로 이 지역(地域) 삼림식생(森林植生)을 분석(分析)하였던 바, 다음과 같이 요약(要約)할 수 있었다. 1) 이 지역(地域) 삼림식생(森林植生)은 산지림(山地林)과 계곡림(溪谷林)으로 구분(區分)할 수 있었으며, 2) 산지림(山地林)은 A. 소나무군락(群落) B. 소나무군락(群落) C. 신갈나무군락(群落)으로, 계곡림(溪谷林)은 느티나무군락(群落)으로 구분(區分)되었다. 3) 소나무군락(群落)은 1. 소나무 전형군(典型群) 2. 소나무-산오리나무군(群) 3. 소나무-대팻집나무군(群)으로, 신갈나무군락(群落)은 1. 소나무-까치박달군(群) 2. 산벚나무-산수국군(群)으로 구분(區分)되었고, 느티나무군락(群落)은 1. 고로쇠나무군(群), 2. 만목성(蔓木性) 식물군(植物群)으로 구분(區分)되었다. 4) Pfister와 풍원(豊源)의 식생분석법(植生分析法)은 다목적(多目的) 임업경영(林業經營)이나 입체적(立體的) 삼림이용(森林利用)을 위한 지침(指針)을 마련하는데 효과적(效果的)인 것으로 사료(思料)되었으나 각(各) 지역(地域) 삼림(森林)에 대한 식생분석(植生分析) 자료(資料)가 많이 있어야 객관적(客觀的)인 응용(應用) 方法(方法)이 제시(提示)될 것 같다.

• Journal of Plant Biology
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• 제13권1호
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• pp.33-46
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• 1970

Pinus densiflora stands are common secondary forest communities on infertile soils in Korea. The stands are results of long severe past biotic pressure such as cutting, burning and grazing. These could be regarded as biotic climax in Korea. Because of their prevalent occurrence, relatively simple species and age composition, and their domestic economic importance, study of their distributional patterns may give some basic knowledge for better utilization of land resources in Korea. To detect distributional patterns and interspecific associations ten pine stands, each of which was homogenious with respect to topography and physiognomy, were subjectively selected from pine stands in Kyunggi Province near Seoul in 1969 and were made object of this study. Four contiguous systematic samples of count for trees, shrubs and seedlings from belt transects were collected from homogeneous areas within ten natural pine stands. The belt transect was 64m or 128m in length, and 1m, 2m or 4m in width. Basic units within the transect ranged from 64 to 256. The data from the contiguous transects were analysed in terms of multiple split-plot experiment. Departure from randomness of stem distribution, i.e., pattern, was tested in terms of variance mean ratio. For the detection of association between species, correlation coefficient was calculated for different block sizes. The values of ${\gamma}$ were tested by the usual t-test. Fine trees within one of the stands showed significant regular distribution through out the blocks. Within other eight stands pines were randomly distributed at basic unit with 4$\times$4m, 2$\times$2m, 2$\times$1m and 1$\times$1m. One significantly clumped distribution at basic unit 2$\times$2m, however, was observed from one of the pine stands. These randomly distributed groups were themselves significantly regularly distributed throughout the blocks for four pine stands. For the other four pine stands, in addition to the random distribution at the basie unit(the primary random group), randomly distributed groups with 32m dimension(the secondary random groups) were also observed. Both the primary and the secondary random groups were significantly regularly distributed at the rest of blocks. Pine seedlings were not distributed randomly thoughout the blocks. Within three of the ten stands they were contagiously distributed. Important shrub species underneath pines such as Querus serrata, Q. acutissima, Leapedeza intermedia, Rhododendron Yedoense var. poukhanenae, Juniperus utilis, Rhododendron mucronulatum var. ciliatum shnwed consistently similar distributional pattern with the pine at each stand. The shrub species pairs; Rhododendron Yedoense var. poukhanenae/Quercus serrata, Rhododendron mucronulatum var. ciliatum/Lespedeza intermedia were significantly negatively associated from 1m to 4m dimensional block sizes but became significantly positively associated from 8m sized blocks on. On the other hand the shrub species pairs; Lespedeza intermedia/Robinia Pseudoacacia, and Lespedeza bicolor var, japonica/Lespedeza intermedia were also significnalty negatively associated from 1m to 8m sized blocks but became significantly positively associated from 16m sized blocks on. The associational pattern between Rhododendron mucronul tun var. poukhanenae and Lespedeza intermedia was not consistent throughout the stands. In some stands negative associations were observed throughout the blocks except NS 32. From these observatons micro-edaphic variation within the pine stands seems not to be great enough to cause distributinal difference of pine trees within the ten pine stands. Among each species and pine seedings, however, the edaphic variation within the pine stands may be great enought to cause distributional variation.