• Journal of the Korean Wood Science and Technology
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• v.46 no.6
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• pp.726-734
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• 2018

In this study, for using effectively domestic (temperate) small and medium diameter logs as a wooden floorboard, cross-laminated wood panels were manufactured using domestic larch and tulip woods as a base material for teak and merbau wood flooring, and static bending strength performances were measured to investigate the applicability as the base materials of wooden flooring in place of plywood. Static bending MOE was much influenced by the strength performances of the top layer lamina than that of the laminae for base materials. Bending MOR showed the higher values in tulip wood that was hardwoods than in larch wood that was softwoods regardless of the strength performances of the top layer laminae, and it was found that the values were much influenced by the strength performances of the base materials used in the core and bottom layers. However these values were 1.4-2.5 times higher values than the bending strength of the wooden floorboards specified in KS, it was found that it can be sufficiently applied to the base materials of wooden floorboards in place of plywood.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.45-52
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• 2008

The objectives of this study are to explain a supply plan of domestic softwood log by long-term prospect of MDF production to stably promote industry of MDF. For it, we developed the long supply function as Ordinary Least Squares Method. Between 2005 and 2050, it was estimated that quantity of domestic production of MDF increased from 1,653 thousand $m^3$ to 2,041 thousand $m^3$. In 2050, quantities of domestic softwood log used by raw materials to product MDF of 2,041 thousand $m^3$ were estimated to be used about 1,355 thousand $m^3$. Exampling Pinus rigida used presently by raw materials to product MDF, cutting area of it is estimated to be 10,828 ha per year. And larch is cutted about 9,160 ha per year. This study estimated annual softwood log cutting amount and total afforestation area at 2050 year by 3 scenarios which are 35%, 45% and 55% about use of domestic softwood log for MDF production. If we do a criterion of cutting area, we advantage to plant larch. But the species of trees are use and growth property. We think that the afforestation policy must be performed on the base of those to supply raw materials of MDF. Although government plans hardwood afforestation policy after cutting Pinus rigida, it needs to support and manage certainly afforestation area of softwoods to need to supply raw materials of MDF to stably promote industry of MDF.

• 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 the Korean Wood Science and Technology
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• v.43 no.1
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• pp.60-67
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• 2015

In order to evaluate the bond performance of domestic larch glulam and the glass fiber reinforced plastic (GFRP) rod, the specimen with the GFRP rod bonded-in domestic larch glulam for pull-out test was produced. The test was carried out using various specimens with different gluing depth, width of glue-line and type of adhesive. The cantilever type rahmen structure specimen with bonded-in GFRP rods was produced based on the result of pull-out test, and its moment resistance performance was compared and examined with the moment resistance performance of slotted-in steel plate specimen. As a result of the pull-out test, the most excellent bond performance was found when the insertion depth of GFRP rods was 5 times larger than the diameter of GFRP rods. When the glue-line thickness was 1 mm, the bond performance improved by 17%~29% in comparison to the bond performance in the case of the glue-line thickness of 2 mm. Also, the bonded strength of the specimen used with poly-urethane adhesive was 2.9~4.0 times greater than the bonded strength of specimen used with resorcinol adhesive. The cantilever type rahmen structure specimen with bonded-in GFRP rods showed the moment resistance performance 0.82 times lower in comparison to the slotted-in steel plate specimen used with the drift pin, but the initial stiffness was similar as 0.93 times.

• Journal of the Korea Furniture Society
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• v.26 no.3
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• pp.222-228
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• 2015

To evaluate the natural decay durability of valuable domestic softwoods which are used for preservative treatment in our country, we carried out decay test by European standard method. Of all test wood species, Japanese larch (Larix leptolepis) showed slightly high natural decay durability compared to other 4 wood species, Japanese red pine (Pinus densiflora), pitch pine (Pinus rigida), Japanese cedar (Cryptomeria japonica), and scots pine (Pinus sylvestris). However, all of evaluated domestic softwood species in this study caused high weight losses over about 30% in heartwood by test fungus, Poria placenta. We can hardly expect a good natural decay durability from these softwood species. According to the classification of the natural durability of European standard (EN 350-1), they are classified into "Not durable" or "Slightly durable". Therefore, if using these softwoods as exterior materials, we must do preservative treatment to ensure durability.

• Journal of the Korea Furniture Society
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• v.24 no.1
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• pp.60-69
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• 2013

Timber is an eco-friendly material that is suitable for low carbon and green growth, and recently, studies on utilization and manufacture of timber are increasing. Thus, we need a stable supply of wood working materials for the formative element and widespread function of timber. It is necessary to develop the use of timber because it enhances the added value of this material by making the most of it. In this way, skin-timber is an appropriate material for life articles because skin-timber has a variety of functions including the ability for storage use, the beauty of structure, the ability to maintain heat and insulation, and the capability to control humidity. In this study, I developed household items using skin-timbers that are made up of circular columns and square columns of pine, larch, and yellow popular. The circular and square columns have an inner hole that is approximately 90% of the external structure's width. I intended for the concept of these designs to display creativity considering functionality and productivity. These items are life articles and furniture for modern people. They are eco-friendly products that are varnished with traditional lacquer and natural oil. According to the result of this study, skin-timbers are made of domestic pine, larch, and yellow popular and are resource of furniture, household items, and woodcraft. I believe skin-timber is not only a useful material for processability and design applicability, but it also has the capability to be a multifunctional and high value-added material. Also, if the standards, such as cortex thickness, outside diameter, and length, of skin-timber are producted diversely, I believe skin-timber can be have more the possibility of industrial products' development.

• Journal of the Korean Wood Science and Technology
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• v.45 no.2
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• pp.202-212
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• 2017

This study was to establish the interrelation between chemical compositions and near infrared (NIR) spectra for the classification on distinguishability of domestic gymnosperms. Traditional wet chemistry methods and infrared spectral analyses were performed. In chemical compositions of five softwood species including larch (Larix kaempferi), red pine (Pinus densiflora), Korean pine (Pinus koraiensis), cypress (Chamaecyparis obtusa), and cedar (Cryptomeria japonica), their extractives and lignin contents provided the major information for distinction between the wood species. However, depending on the production region and purchasing time of woods, chemical compositions were different even though in same species. Especially, red pine harvested from Naju showed the highest extractive content about 16.3%, whereas that from Donghae showed about 5.0%. These results were expected due to different environmental conditions such as sunshine amount, nutrients and moisture contents, and these phenomena were also observed in other species. As a result of the principal component analysis (PCA) using NIR between five species (total 19 samples), the samples were divided into three groups in the score plot based on principal component (PC) 1 and principal component (PC) 2; group 1) red pine and Korean pine, group 2) larch, and group 3) cypress and cedar. Based on the chemical composition results, it was concluded that extractive content was highly relevant to wood classification by NIR analysis.

• Journal of the Korea Furniture Society
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• v.19 no.6
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• pp.460-465
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• 2008

When wood is exposed to natural weathering and UV radiation discoloration progresses. The color variation of heat-treated wood was investigated. Four domestic species were selected and heat-treated at $220^{\circ}C$ and naturally weathered for 42 days. Their colors were measured with a portable colorimeter. The color variations were different between species. The Korean red pine specimens were highly discolored by the natural weathering even though they were heat-treated. In contrast to Korean red pine, Korean pine is less discolored. The maximum color difference of larch was lower than Korean red pine. All specimens of birch exceeded the color difference criterion of 15 after 25 hours with the maximum of 28.

• Journal of the Korean Wood Science and Technology
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• v.24 no.3
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• pp.90-100
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• 1996

두께가 20mm 와 30mm 이고, 폭이 40mm 와 60mm인 600mm 길이의 낙엽송 제재목에 응력파 시험을 실시하였다. 모든 시험편은 생재 상태로 구입 후 함수율 27%, 22%, 17%과 12%조건으로 조습 처리하였다. 함수율 변화에 따른 응력파 속도와 영계수를 구하기 위한 응력파 시험을 4종류의 함수율 조건에서 실시하였다. 응력파 속도와 응력파 시험으로부터 구한 영계수는 시편의 함수율, 치수, 그리고 시험편의 옹이와 옹이 주변 목리의 상호작용에 의해 영향을 받았다. 모든 함수율 및 각 함수율 조건에서 응력파 속도는 응력파에 의해 구한 영계수와 양호한 상관관계를 나타냈다. 응력파 속도와 응력파 시험으로 구한 영계수는 함수율이 증가할 때 비선형적으로 감소하였으나, 함수율 25% 이상에서는 응력파에 의해 구한 영계수의 변화가 거의 없었다.

• Journal of the Korean Wood Science and Technology
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• v.40 no.1
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• pp.26-37
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• 2012

Recently, the demand and supply on the Hanok have been increased. However, Hanok should be requested larger section of structural members because of excessive roof weight. So, structural skin-timber was manufactured to get a lightweight structural member. The structural skin-timber has exterior shape with larger section but a great volume of wood be removed. The reduced strength of structural skin-timber can be supplemented by hybridizaion of structural member. Japanese larch and Domestic pine were used to manufacture the structural skin-timber. Structural skin-timbers of rectangular shape and cylinder shape were manufactured and tested to evaluate the bending properties. The intended strength property could not be obtained because member had been suffered severe damage by precision deficiency of manufacturing machine. However, if precision of manufacturing machine would be improved and additional hybridizaion of structural skin-timber would be done, lightweight structural member will be able to be manufactured. Structural skin-timber did not showed statistical significancy between two species, so it is possible to use pine mixed with larch. Only MOR of larch showed statistical significancy between rectangular shape and cylinder shape, so it is necessary to use of those as separate things. However, the rest of skin-timber can be judged mixed using because of non statistical significancy. The objective of this study was the development of lightweight larger structural member with relatively strength. If hybrid member of skin-timber could be developed with wood-ceramics, lightweight steel and more, it can be possible to be used as a building material of Hanok, interior material, post & beam construction material and more.