• Journal of the Korean Wood Science and Technology
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• v.3 no.1
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• pp.3-15
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• 1975

How to stabilize wood against shrinking and swelling in variable atmospheric moisture conditions is important to the wood-using industry and a challenge to research. Polyethylene glycol stabilize wood by bulking the fiber. PEG also serve as a chemical seasoning agent, suppress decay in high concentrations, and have slight effect on physical properties, gluing or finishing. The study designed to determine the effect of PEG-400 on the dimensional stabilization of local hardwoods for wood carvings that could supply a greatly expanding tourist trade and making curved furniture parts, lamp stands and other decorative objects, and possible gunstock. The species examined were 6 species, Seo-Namoo (Carpinus laxiflora), Cheungcheung-Namoo (Cornus controversa), Gorosae-Namoo (Acer mono), Karae-Namoo (Juglans mandshurica), Jolcham-Namoo (Quercusserrata) and Sanbud-Namoo (Prunus sargentii), used as block of 5cm thick radially to the grain, 7cm wide tangentially, and 70cm long parallel to the wood grain. All these test piecies were conditioned above the fiber saturation point before impregnation. The stabilization effects were determined for PEG-400 treated woods in a 50 percent solution for 20 days. The following conclusions were obtained. PEG retentions increased with treating time. It was more effective to treat at 60$^{\circ}C$ than at room temperature. In degree of PEG-400 impregnation on species, Cheungcheung-Namoo havinglow specific gravity had the highest retentions, 68.77% but the lowest, 56.33% was shown in Jolcham-Namoo with high specific gravity. Specific gravity of treated wood increased considerably with effectiveness of polymer loading. The increases in specific gravity were 5.36 to 13.16 percent. The highest was Jolcham-Namoo, the lowest Karae-Namoo. On the dimensional stability, a 40 percent of effectiveness of polymer loading was just as effective as 60 percent in reduction in water absorptivity (RWA), antishrinkage efficiency (ASE) and antiswelling efficiency (AE), and from over 60 percent they increased more rapidly. Also species response varied considerably. ASE was 30.12 to 69.97 percent tangentially and 27.86 to 56.37 percent radially, AE 34.06 to 73.76 percent tangentially and 30.11 to 70.12 percent radially, and RWA 42.31 to 65.32 percent. No differences in volume swelling among the 6 species were observed. Its values were ranged from 14.98 to 19.55 percent and also increased with PEG retentions. On the mechanical properties, the strengths very much decreased with PEG-400 loadings as shown in Figure 12; that were 11.41 to 22.90 percent in compression, 21.61 to 34.35 percent in bending and 22.83 to 36.83 percent in tensile strength. PEG retention in cell wall was less than 1 percent and the most of PEG were immersed in cell lumen. Except for Korae-Namoo, effectivenesses of polymer loading were as much high as 61.58 to 75.02 percent. This is believed to be due to the effect of PEG-400 on excellant dimensional stability of treated woods.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.3
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• pp.72-83
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• 2015

A plant diversity, which consists of indigenous plant community with Orientla thuja community (Natural monument no. 1) in Dodong, Daegu, is identified and analyzed as ecological characteristic to consider worth plants and vegetation resource of the region. The vascular plants of Thuja orientalis community were listed as 219 taxa (3.7% of all 4,881 taxa of Korean vascular plants); 67 families, 147 genera, 199 species, 16 varieties, and 4 forms. Vulnerable species (VU) and least concerned species (LC) were recorded based on IUCN standard; Koelretueria paniculata (VU), Thuja orientalis (LC), and Exochorda serratifolia (LC). Although the study site is a non-limestone area, a total of 15 taxa of calciphilous plants were identified; Cheilanthes argentea, Hypodematium glandulosopilosum, Asplenium retamuraria, Thuja orientalis, Spiraea blumei, Smilax sieboldii, etc. A total of 4 taxa endemic plants were identified; Prunus mandshurica for. barbinervis, Lespedeza maximowiczii var. tomentella, Forythia koreana (artificial origin), and Veronica pyrethrina. Among the list, 8 taxa of naturalized plants were identified; Fallopia dentatoalalta, Rumex crispus, Nasturtium officinale, Bidens frondosa, Erigeron annuus etc. Naturalization rate (NR) was 3.6%, of all 219 taxa of vascular plants and urbanization index (UI) was 2.2% of all 321 taxa of naturalized plants. Thuja orientalis occupies a lot of indigenous landscape in this study area which is the southern-limited part of a natural distribution where it can survive. The T. orientalis community, where indigenous plants have formed a characterful species composition based on habitat, has been confirmed as a worth national vegetation resource in an indigeous flora. It has been considered of plans for persistent conservation.

• Korean Journal of Environment and Ecology
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• v.26 no.1
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• pp.39-45
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• 2012

To explore on the defense strategies against hervivory of 67 broadleaved tree species, morphological characteristics of the leaf, leaf domatia structure and the number, herbivores insects and mites on the leaves, collected from the trees growing in Taean-gun, Chuncheongnam-do were investigated. 46 broadleaved tree species(68.7%) had the domatia structures, and 21 species including Quercus salicina and Magnolia grandiflora did not. 31 species including Juglans mandshurica and Carpinus laxiflora reveals tuft type, 12 species including Quercus dentata and Corylus heterophylla reveals pocket+tuft type, and 2 species, Sorbus alnifolia and Prunus yedoensis does pocket type, and Viburnum odoratissimum var. awabuki does pouch type. Domatia number per leaf proves the highest figures, 23.4/leaf for Quercus dentata. Plant defense strategies using leaf lower-surface trichomes of Magnolia grandiflora reveals dense villous, those of Populus alba and Vitis vinifera reveals dense pilose, that of Elaeagnus umbellata does dense scaly hairs, that of Pueraria lobata does dense strigose. Plant defense strategies using extrafloral nectaries were adapted 23 tree species(34.3%). Observed examples are Prunus tomentosa, Ficus carica, Viburnum dilatatum and Carpinus laxiflora. Predatory mites were observed on the leaves of 40 tree species(59.7%), and mean values of predatory mites was highest values 23.4/leaf in Quercus dentata. Minute arthropods destroying the leaf of broadleaved trees. are such as Periphyllus californiensis, P. viridis, Diaspididae sp., gall mites, thrips, and total numbers observed were odered gall mites, Diaspididae sp., aphids and thrips. Natural enemies of these hervivores arthropods are such as predatory mites, Chilocorus rubidus, Coccinella septempunctata and the nymph, Aphidius ervi. These results indicate that defense strategies including protective mutualisms may be frequent in the temperate broadleave trees.

• Journal of the Korean Wood Science and Technology
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• v.2 no.3
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• pp.3-16
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• 1974

One of the disadvantages of. wood and wood products is their hydroscopicity or dimensional instability. This is responsible for the loss of green volume of lumber as seasoning degrade. Dimensional stabilization is needed to substantially reduce seasoning defects and degrades and for increasing the serviceability of wood products. Recently, considerable world-wide attention has been drawn to the so-called Wood-Plastic Composites by irradiation-and heat-catalyst-polymerization methods and many research and developmental works have been reported. Wood-Plastic Composites are the new products having the superior mechanical and physical properties and the combinated characteristics of wood and plastic. The purpose of this experiment was to obtain the basic data for the improvement of wooden materials by manufacturing WPC. The species examined were Mulpurae-Namoo (Fraxinus, rhynchophylla), Sea-Namoo (Carpinus laxiflora), Cheungcheung-Namoo (Cornus controversa), Gorosae-Namoo (Acermono), Karae-Namoo(Juglans mandshurica) and Sanbud-Namoo (Prunus sargentii), used as blocks of type A ($3{\times}3{\times}40cm$) and type B ($5{\times}5{\times}60cm$), and were conditioned to about 10~11% moisture content before impregnation in materials humidity control room. Methyl methacrylate (MMA) as monomer and benzoyl peroxide (BPO) as initiator are used. The monomer containing BPO was impregnated into wood pieces in the vacuum system. After impregnation, the treated samples were polymerized with heat-catalyst methods. The immersed weights of monomer in woods are directly proportionated to the impregnation times. Monomer impregnation properties of Cheungcheung-Namoo, Mulpurae-Namoo and Seo-Namoo are relatively good, but in Karae-Namoo, it is very difficult to impregnate the monomer MMA. Fig. 3 shows the linear relation between polymer retentions in wood and polymerization times; that is, the polymer loadings are increasing with polymerization times. Furthermore species, moisture content, specific gravity and anatomical or conductible structure of wood, bulking solvents and monomers etc have effects on both of impregnation of monomer and polymer retention. Physical properties of treated materials are shown in table 3. Increasing rates of specific gravity are ranged 3 to 24% and volume swelling 3 to 10%. ASE is 20 to 46%, AE 14 to 50% and RWA 18 to 40%. Especially, the ASE in relation to absorption of liquid water increases approximately with increase of polymer content, although the bulking effect of the polymerization of monomer may also be influential. WPCs from Mulpurae-Namoo and Cheungcheung-Namoo have high dimensional stability, while its of Karae-Namoo and Seo-Namoo are-very low. Table 4 shows the mechanical properties of WPCs from 6 species. With its specific gravity and polymer loading increase, all mechanical properties are on the increase. Increasing rate of bending strength is 10 to 40%, compression strength 25 to 70%, ;impact bending absorbed energy 4 to 74% and tensile strength 18 to 56%. Mulpurae-Namoo and Cheungcheung-Namoo with high polymer content have considerable high increasing rate of strengths. But incase of Karae-Namoo with inferior monomer impregnation it is very low. Polymer retention in cell wall is 0.32 to 0.70%. Most of the polymer is accumulated in cell lumen. Effective. of polymer retention is 58.59% for Mulpurae-Namoo, 26.27% for Seo-Namoo, 47.98% for Cheungcheung-Namoo, 25.64% for Korosae-Namoo, 9.96% for Karae-Namoo and 25.84% for Sanbud-Namoo.