• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.76-82
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• 2006

The dried ground needles (2.0 kg) of Chamaecyparis pisifera (Sieb. et Zucc.) Endlicher were extracted with acetone-$H_2O$ (7:3, v/v), concentrated, and fractionated with a series of n-hexane, methylene chloride, ethyl acetate and water on a separation funnel. Each fraction was freeze dried, then a portion of ethyl acetate soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-n-hexane mixture as eluents. The isolated compounds were identified by cellulose TLC, $^1H$-, $^{13}C$-NMR, COSY, HETCOR, FAB and EI-MS. (+)-catechin, taxifolin-3-O-${\beta}$-D-xylopyrano-side, quercetin-3-O-${\alpha}$-L-rhamnopyranoside were isolated from the ethyl acetate soluble fraction of Chamaecypairs pisifera needle. Antioxidative tests on the isolated compounds indicated that all of the compounds showed similar values to ${\alpha}$-tocopherol and BHT as controls.

• Journal of the Korean Wood Science and Technology
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• v.52 no.1
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• pp.58-69
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• 2024

To evaluate the adhesive characteristics of mixed cross-laminated timber (CLT) using domestic softwoods structural lumber proposed by KS F 3020 and yellow poplar, penetration depth of adhesive and thickness of bonding line were analyzed based on the results of boiling water soaking delamination. 3 Types of adhesives and 2 types of major layer were divided into a 5 ply CLT using yellow popular as minor layer. The bonding performance of the mixed CLT as structural members was evaluated based on the KS F 2081. The thickness of bonding line between layers of the mixed CLT was measured with a scanning electron microscope, and the adhesive penetration depth in the layer members was measured with an optical microscope. As a result of boiling water soaking delamination test of mixed CLT, the CLT specimens using PRF and PUR adhesives met the requirements of KS F 2081. It was verified that the penetration path of the adhesive in the layes was mainly through the tracheid cell in the case of Japanese larch and Korean red pine layers, and through the vessel and radial tissue in yellow popular layers. The penetration depth of the adhesive was the highest for the PRF adhesive under the same pressing time conditions, and the thickness of the bonding line was in inverse proportion to the penetration depth in the case of the PUR adhesive.

• Journal of the Korean Wood Science and Technology
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• v.42 no.6
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• pp.666-674
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• 2014

In this study, we investigated mechanical properties of Korean softwoods after applying thermal compression. Density of compressed woods was notably increased with thermal compression. In case of 50% compression set, density of Korean pine (Pinus koraiensis), Japanese red pine (P. densiflora), and Larch (Larix kaempferi) wood was increased by 71%, 74%, and 76%, respectively, when compared to the control group. The strength of woods was increased and quality of the woods became homogeneous with an increases in the compression set. On the 50% compression set, the compressive strength, bending strength, and hardness of Korean pine wood was increased by 76%, 83%, and 55%, respectively compared to the control group. Longitudinal compressive strengths of Japanese red pine wood increased by 69%, 130%, and 76%, respectively and those of Larch wood increased by 77%, 120%, and 44%, respectively. In thermal compression wood, mechanical properties of Larch wood was the highest, while those of Korean pine wood were the lowest. However, Japanese red pine wood showed the highest in the increase rate of mechanical properties after the thermal compression.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.3
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• pp.38-45
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• 1998

Soil and water contamination caused by the abundant use of agricultural chemicals including herbicides and fertilizers draws public concerns since these chemicals may pollute the agricultural lands as well as the food products grown on these lands. As a method to reduce the use of agricultural chemicals mulching with thin plastic film has been commonly practised for many years. Although use of the plastic film for mulching is very effective in preventing the growth of weed, it is almost impossible to remove all of the plastic film from the agricultural land and the remaining film eventually contaminates the soils. Therefore, it is very imperative to develop a mulching material that decomposes completely to prevent soil pollution problems and to enhance the competitive edge of domestic agriculture. Mulch papers are believed to have many positive characteristics in preventing problems caused by the plastic mulch film since it decomposes completely after use. However, the basis weight of mulch papers needs to be reduced to improve its handling properties and to reduce the raw material costs of pulps. In this paper the possibilities of using domestic old corrugated containers in producing mulch papers were examined. Also use of unbleached softwood kraft pulps and dry strength additives were exploited along with two-layered sheet forming technology in decreasing the basis weight of the mulch paper. Results showed that reduction of 20g/$m^2$ of basis weight of mulch paper was possible by the appropriate raw material selection and application of strength resin. To use the mulch papers in paddy fields, however, further research to improve its durability should be pursued.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.73-83
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• 2006

The dried needles (1.5 kg) of Abies koreana and Abies holophylla were ground, extracted with acetone-$H_2O$ (7:3, v/v), concentrated, and fractionated with a series of hexane, methylene chloride, ethyl acetate and water on a separatory funnel. Each fraction was freeze dried, then a portion of ethyl acetate soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. The isolated compounds were identified by cellulose TLC, $^1H$, $^{13}C-NMR$, COSY, HETCOR, FAB and EI-MS. The needles of Abies koreana and Abies holophylla contained a large amount of aromadendrin-7-O-${\beta}$-D-glucopyranoside (compound III), polydatin (compound VI), (-)-rhododendrol-2-O-${\beta}$-D-glucopyranoside (compound VII), in addition to a small amount of (+)-catechin (compound I), kaempferol-3-O-${\beta}$-D-glucopyranoside (compound IV), myricetin-3-O-${\beta}$-D-glucopyranoside (compound V), naringenin-7-O-${\beta}$-D-glucopyranoside (compound II). DPPH analysis was also tested to investigate the antioxidative effects on the isolated compounds and (+)-catechin and polydatin were effective.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.456-462
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• 2015

365 pieces of domestic $38{\times}140{\times}3600mm$ Red pine structural lumber were machine graded conforming to a softwood structural lumber standard (KS F 3020). The allowable bending stresses calculated for each grade were compared with the values currently tabulated in the standard. Four calculation methods for lower $5^{th}$ percentile bending stress were non-parametric estimation with 75% confidence level, 2-parameter and 3-parameter Weibull distribution fit, and bending modulus of rupture (MOR)-modulus of elasticity (MOE) regression based method. Only the data set of Grades E8, E9, and E10 were statistically eligible for the $5^{th}$ percentile calculation. The MOR-MOE regression based method only was able to estimate the lower $5^{th}$ percentile values theoretically for the full range of grades. The results showed that all allowable bending stresses calculated were lower than the design values tabulated in the standard. This implies that the current machine grading system has the pitfall of structural safety. Improvement in current machine grading system could be achieved by introducing the bending strength and stiffness combination grade system.

• Journal of the Korean Wood Science and Technology
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• v.12 no.1
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• pp.11-30
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• 1984

This study was executed to offer the basical data needed to the plywood industry as examining on the wood characteristics of veneer species that grow in Korea. According to the aggravation of log import from foreign countries caused by the gradual exhaustion of wood resources in recent years, the study on wood characteristics of veneer species growing in Korea should be carried out preferentially in promotion of the domestic timber utilization and development of it's processing technique for plywood industry. 50 commercial veneer species in this study were selected from 33 genuses, and general macroseopical wood characteristics for them were examined and described by the species. And also keys for the identification based on gross features were briefly prepared and presented by gymnosperm and angiosperm respectively.