• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.40-47
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• 1988

Our plywood manufacturing industries which entertained prosperous stage in late 1970's have come to be in face of the problems of conceedingly obtaining good quality logs and yield up-grading, which is considered by future-replaceable forest resources. In view of this point, manufacturing characteristic on softwood plywood using Japanese larch, pitch pine as domestic plantation species, and western hemlock as foreign species was studied. In this study, veneer- and plywood manufacturing yields were discussed in relation to log properties and veneer defects (knots). The summarized conclusions were as follows: 1. The majority of sample logs belonged to second grade on the standard. And, eccentricity of larch was the highest 11%, about 2 times those of pitch pine, hemlock. 2. Knot frequency of occurrence of larch reached 19% within log height 8m, and pitch pine 13% within 4m. Correspondingly, the log height of larch available for plywood manufacture was higher by about 2 times that of pitch pine. 3. In the knot types, most of knots of larch appeared dead, whereas those of pitch pine and hemlock appeared live. In size of knots, larch and hemlock showed relatively small 1-2cm dia. by 70% or more and pitch pine did the larger 24cm by 65%. Generally the more knot emerged in the inner side of veneer than the outer. 4. Plywood manufacturing yields by peeling with spindle revolution lathe were 37% in larch > 32% in hemlock> 26% in pitch pine. S. Jointed core veneer yields by peeling with outer perimeter back-up lathe were 55% in hemlock> 53% in larch> and 48% in pitch pine.

• Journal of the Korean Wood Science and Technology
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• v.25 no.1
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• pp.8-14
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• 1997

Stress wave velocity, wave impedance, and stress wave elasticity of small, clear bending specimens of five domestic softwoods (Pinus densiflora, Pinus koraiensis, Chamaecyparis obtusa, Cryptomeria japonica, and Larix leptolepis) and four tropical hardwoods(Kempas, Malas, Taun, and Terminalia) were correlated with static bending modulus of elasticity(MOE) and modulus of rupture(MOR). The degree of correlation between stress wave parameters and static bending properties was dependent on wood species tested. Stress wave elasticity and wave impedance were better predictors for static bending properties than stress wave velocity for each species individually and for softwood or hardwood species taken as a group, even though elasticity and impedance were nearly equally correlated with static bending properties apparently. Based upon the correlation coefficient between stress wave parameters and static properties, stress wave elasticity and wave impedance were found as stress wave parameters which can be used for the purpose of the reliable and successful prediction of bending properties. The degree of correlation between static MOE and MOR was also different according to wood species tested. Static MOE was nearly as well correlated with MOR as was stress wave elasticity. The results of this research are encouraging and can be considered as a basis for further work using full-size lumber. From the results of this study, it was concluded that stress wave measurements could provide useful predictions of static bending properties and was a feasible method for machine stress grading of domestic softwoods and tropical hardwoods tested in this study.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.3
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• pp.59-68
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• 2001

Essential oils extracted from Chamaecyparis obtusa were applied to make antibacterial corrugating liner. The quantitative analysis of the essential oils was carried out by GC-MS, which showed that the monoterpenes as a basic component of the essential oils extracted from Chamaecyparis obtusa in the domestic mountain were greater in amount than those in China. The antibacterial activity was then examined with Tyromyces palustris and gram-negative/positive bacteria. The papers treated with the essential oils desplayed great resistance against T. Palustris and gram bacteria but the best results were obtained with the handsheet formed by softwood bleached kraft pulp rather than the liner by OCC. The low antibacterial activity of the liner was considered to be due to starch components which could be readily attacked by the fungi.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.82-89
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• 2004

Two kinds of chemicals (RNF-3 and RNF-4) with high anti-mold effectiveness against stored fungi causing fungal discoloration was selected from among the six kinds of fluoride-based chemicals in the preceding study. In this study, the anti-mold test using 16 species fungi isolated from the softwood lumbers which were fungal discolored and field test in the sawmill was carried out to prove the feasibility for practical using of selected chemicals.For the isolated fungi, the RNF-3 consist of F and Cu showed high mycelial growth control in the PDA medium and fungicidal effectiveness in the japanese red pine (Pinus densiflora), korean pine (Pinus koraiensis) and radiata pine (Pinus radiata) when the concentration was 2% or more. However the RNF-4 consist of F only was not effective compared with RNF-3 because of mycelial growth in the PDA medium and wood treated with 2% or more chemical solution. The RNF-3 also showed a strong anti-mold effectiveness because there was no fungal discoloration for the radiata pine boards treated by 2% and 10 min. soaking in the field test. These results mean that RNF-3 can be used as domestic anti-stain chemicals for prevention of fungal discoloration of the softwood lumber

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.521-530
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• 2011

Nowadays, market demand of structural Glulam is growing and diversifying. The durability of Glulam should be significantly considered when they are intended to apply for out-door use such as timber bridge and pergola. This study was aimed to develop the manufacturing process of preservative treated structural Glulam using domestic softwood species. 10 m long structural Glulam were manufactured from domestic pitch pine logs with CuAz-3 preservative treatment. At each manufacturing process, the production yield was evaluated. Finally, bending tests were performed to verify the structural performance of manufactured Glulam. From the results, it was shown that the preservative treatment process hardly influenced on the production yield. But domestic pitch pine was proved to not be suitable for making the preservative treated Glulam due to the large difference of preservative permeability between sapwood and heartwood.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.498-506
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• 2010

To use domestic softwood for structural lumber, appropriate grading system for quality, production and distribution condition of domestic lumber should be prepared. Kim et al. developed an automatic image processing system for grading domestic structural lumber (2009a and b). This study was carried out to investigate optimal image merging conditions for improving performance of image input system which is the key technique of image processing system, developed in the previous paper. To merge digital images of Korean larch lumber, choosing the green channel information of obtained image data showed the most accurate merging performance. As a pre-treatment process, applying Y-derivative Sharr's kernel filter could improve the image merging accuracy, but the effect of camera calibration was imperceptible. The optimal size of template image was verified as 30 pixel widths and 150 pixel heights. When applying the above mentioned conditions, the error length of images was 3.1 mm and the processing time was 9.7 seconds in average.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.197-202
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• 2007

This study is conducted to investigate the factors affecting lumber conversion rate of sawmill industry in South Korea. Data were obtained from the survey of 38 sawmills in all geographic regions of South Korea. The variables examined in this study were region, softwood/hardwood log, domestic/imported/both log, the number of power-driven carriages (PDC) installed, the year when and country where PDCs was manufactured, the horse power of PDC, the number of labors required to operate each PDC, the sawing capacity of mill (mill size), and the types of major product and by-products. The lumber recovery factor (LRF) of sawmills were significantly influenced by the origin of logs, level of PDC automation, sawmill size, and size of logs (measured in diameter and length) while not by the location of the mill, types of major product and by-product, log species, and characteristics of PDC. Although these results provide useful information for understanding the technological characteristics of the Korean sawmill industry, further investigation with larger sample is necessary to reveal the more reliable characteristics of sawmill industry in South Korea.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.383-392
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• 1992

The objective of this study is to evaluate the impacts on the domestic timber supply potential of forest resources management policies such as the extention of forest management infrastruture and setting aside more forest lands for the provision of environmental goods. To this end, the domestic timber supply functions were estimated using time series data for the period 1970-1990 and were used to predict the future trends in timber production in the Republic of Korea. For this purpose, a set of scenarios based on the forest road density and forest inventory growth were designed for the next 40 years. The timber supply behavior in Korea was found to be different by species group : domestic supply of softwood roundwood is inelastic with respect to its ovum price while that of hardwood elastic. The effect of forest road construction on the domestic timber production seems to be insignificant yet. The model simulation aided by policy scenarios revealed that the future timber supply potential will be largely restricted if the policy option with emphasis on the provision of environmental goods from the forest resources were adopted.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.96-103
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• 2003

This study was conducted to evaluate the tensile properties of metal plate connector for the domestic major softwoods, such as Korean red pine, Korean white pine, and Japanese larch. The maximum tensile load of Korean red pine was 3,612kgf in AA type, it was 1.2 and 1.7 times higher load than that of Japanese larch and Korean white pine. In EA type, it was 2,704kgf, and 1.1 and 1.5 times higher than the loads of Japanese larch and Korean white pine. The failure modes of metal plate connector were metal plate withdrawal, plate tensile failure, and wood shear block failure. The failure mode of Korean red pine connector was tensile failure of plate, that is reason of the high tensile load resistance for metal plate connections in Korean red pine. The mechanical properties of metal plate connector could be predicted by the Foschi model parameter. In the initial stage, the Korean red pine connector was stiffer than the other species. The design values for metal plate connector per tooth was 25, 22, and 15kgf for Korean red pine, Japanese larch, and Korean white pine in AA type and 19, 17, and 13kgf in EA type.

• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.184-191
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• 2009

In the southern part of the Korean Peninsula including Jeju-island, the production amount of domestic cedar has increased gradually. However, their low qualities, expected to be caused by the low density and frequent knots, have restricted their practical utilization as the high value-added products. In this study, it is aimed to look for the new uses of domestic cedar and to examine the applicability for lamination lumbers of structural glued laminated timber (glulam). Above all, machine stress ratings for individual sawn lumbers confirmed that modulus of elasticity (MOE) of cedar lumber was lower than that of other common softwood species in Korea. On the other hand, cedar lumbers have enough stiffness to manufacture the structural glulam in accordance with Korean Industrial Standard (KS). The bonding strength and durability also met the KS limitation. Nevertheless, from the result of bending tests for cedar glulam, it was shown that the modulus of elasticity (MOE) did not meet the KS limitation. Therefore, it was concluded that additional researches were needed for reinforcing the stiffness of cedar glulam.