• Journal of the Korean Wood Science and Technology
• /
• 제49권6호
• /
• pp.541-549
• /
• 2021

This paper reports a method to evaluate the residual strength of insect-damaged radiata pine lumber, such as the screw withdrawal strength as a semi-destructive method and a compression parallel to the grain test to assess the density changes after exposure to outdoor conditions. The screw withdrawal strength test was used as a semi-destructive method to estimate the residual density of decayed lumber. A compression parallel to the grain test was applied to evaluate the residual density. Three variables, such as the screw withdrawal strength, compression parallel to the grain, and residual density, were analyzed statistically to evaluate their relationships. The relationship between the residual density and screw withdrawal strength showed a good correlation, in which the screw withdrawal strength decreased with decreasing density. The other relationship between the residual density and compression parallel to the grain was also positively correlated; the compression parallel to the grain strength decreased with decreasing density. Finally, the correlation between the three variables was statistically significant, and the mutual correlation coefficients showed a strong correlation between the three variables. Hence, these variables are closely correlated. The test results showed that the screw withdrawal strength could be used as a semi-destructive method for an in situ estimation of an existing wood structure. Moreover, the method might approximate the residual density and compression parallel to the grain if supplemented with additional data.

• Journal of the Korean Wood Science and Technology
• /
• 제23권2호
• /
• pp.77-82
• /
• 1995

With the aim to utilize pine wood(Pinus densiflora Sieb. et Zucc.) as an interior building materials, such as flooring material, monoethylene glycol(MEG) resin solution was impregnated into greenwood. Specimens of three different qualities, that is, normal wood, resinous wood and compression wood, were prepared. Distribution of resin element(phosphorus) in MEG resin solution-impregnated woods and preservative effectiveness against brown rot fungi(Tyromyces palustris and Serpula lacrymans) of these woods were investigated. The results were as follows: 1. The concentration of phosphorus into cell walls of resinous wood and compression wood was lower compared to that of normal wood. This shows that the quality of wood has an influence on the penetration of MEG resin solution into the wood. It was shown from a leaching test that MEG resin could be leached out easily from the cell walls. 2. The resinous wood and compression wood, even without MEG resin solution impregnation had high decay resistance. For normal wood, significant improvement of preservative effectiveness was observed after impregnation of MEG resin solution. It was shown that MEG resin was leached out from the woods after leaching test, resulting in the reduction of preservative effectiveness. From this result, suitability of MEG resin solution-impregnated woods as an interior materials was recognized.

• Journal of the Korean Wood Science and Technology
• /
• 제44권2호
• /
• pp.184-190
• /
• 2016

Recently, wood is attracting attention as green building interior decoration material. When wood is used as building interior decoration material, excellent dimensional stability and thermal performance is required. In this study, superheated steam treatment process and thermal compression process were applied to flat sawn Pinus koraiensis wood panel in order to improve dimensional stability and thermal performance. According to results of this study, superheated steam treatment process and thermal compression process improve thermal performance and dimensional stability of wood, especially in tangential direction. The spring back in radial direction reduces the effect of thermal compression on dimensional stability of wood in radial direction.

• Journal of the Korean Wood Science and Technology
• /
• 제42권6호
• /
• pp.666-674
• /
• 2014

국산 침엽수재의 용도확장을 위해 열압밀화를 실시하여 압축세트량에 따른 역학적 성능을 조사하였다. 열압밀화 공정에 의해 시험편의 밀도가 크게 향상되었다. 50% 압축 시 대조군 대비 잣나무재가 약 71%, 소나무재가 약 74%, 낙엽송재가 약 76%의 밀도가 증가되었으며, 압축세트량 증가와 함께 시험편의 재질이 균일해진다는 것을 내부밀도분포 분석을 통해 알 수 있었다. 열압밀화에 따른 역학적 성능의 변화는 대조군 대비 50% 압축 시 잣나무재의 경우, 종압축강도가 76%, 휨강도가 83%, 표면경도가 55% 증가하였다. 소나무재는 종압축강도가 69%, 휨강도가 130%, 표면경도가 76% 증가되었다. 낙엽송재의 경우 종압축강도가 77%, 휨강도가 120%, 표면경도가 44% 증가되었다. 국산 침엽수 열압밀화재의 강도성능은 일반적으로 낙엽송재가 가장 높고 잣나무재가 가장 낮았다. 그러나 열압밀화에 의한 강도성능의 증가율은 소나무재가 가장 높았다.

• Journal of the Korean Wood Science and Technology
• /
• 제34권5호
• /
• pp.19-28
• /
• 2006

There has been considerable research in recent times in light-timber med structures in fires. These structures have included horizontal (floor-like) panels in bending and walls under eccentric and approximately concentric vertical loading. It has been shown that compression properties are the most dominant mechanical properties in affecting structural response of these structures in fire. Compression properties have been obtained by various means as functions of one variable only, temperature. It has always been expected that compression properties would be significantly affected by moisture and stress, as well. However, these variables have been largely ignored to simplify the complex problem of predicting the response of light-timber framed structures in fire. Full-scale experiments on both the panels and walls have demonstrated the high level of significance of moisture and stress for a limited range of conditions. Described in this paper is an overview of these conditions and experiments undertaken to obtain compression properties as a functions of moisture, stress and temperature. The experiments limited temperatures to $20{\sim}100^{\circ}C$. At higher temperatures moisture vaporizes and moisture and stress are less significant. Described also is a creep model for wood at high temperatures.

• Journal of the Korean Wood Science and Technology
• /
• 제31권6호
• /
• pp.1-7
• /
• 2003

The phase transformation from cellulose I into cellulose II in woods by way of Na-cellulose I was examined by x-ray diffraction analysis.The formation of Na-cellulose I in woods increased with the increase of treating time in alkali solution. When compression wood was treated with 20% NaOH solution at room temperature for 1 day, the x-ray diagram showed only Na-cellulose I. On the other hand, the x-ray diagram of tension wood showed a mixture of cellulose I and Na-cellulose I. Cellulose I of tension wood could not be transformed completely into Na-cellulose I even after 10-day treatment, but was transformed into Na-cellulose I after 30-day treatment. Na-cellulose I of compression and tension woods was converted to the cellulose I pattern and the mixture of cellulose I and cellulose II, respectively, after washing with water and drying at 20℃. Cellulose I regenerated from Na-cellulose I in wood could not be converted to cellulose II by delignification. Thus, it revealed that the delignification of the alkali-treated wood did not affect their cellulose structures. From the results, therefore, it can be concluded that lignin in woods prevents the formation of the stable Na-cellulose I and the conversion from cellulose I to cellulose II. This means that the conversion of chain polarity of wood cellulose hardly occurs during mercerization because cellulose microfibrils are fixed by lignin which not to be intermingled.

• Journal of the Korean Wood Science and Technology
• /
• 제39권3호
• /
• pp.206-212
• /
• 2011

라디에타 소나무(Pinus radiata D.Don)를 이용하여 압체 온도와 시간에 따른 압밀화 목재의 경도와 치수안 정성을 조사하였다. 압체 온도가 상승함에 따라 표면경도도 함께 증가하였다. 열압체 시간 30분을 기준으로 압체 온도 $70^{\circ}C$에서는 경도 값이 5.0 N/$mm^2$, $220^{\circ}C$에서 15.6 N/$mm^2$으로 312% 향상되었으며, 60분에서는 313%, 90분에서는 224% 향상되는 것으로 나타났다. 치수회복실험 결과 열압체 온도가 상승함에 따라 치수고정효과는 상승한 반면 압체 시간의 증가에 의한 치수고정효과는 미약하였다. 접촉각 측정결과 압체 온도와 시간의 증가와 함께 접촉각도 증가했으며 압체 온도 $220^{\circ}C$에서는 $90^{\circ}$ 이상의 접촉각을 나타내어 표면이 소수성을 나타냄을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
• /
• 제43권1호
• /
• pp.68-75
• /
• 2015

국내산 잣나무재의 바닥재로의 이용을 위해 열압밀화를 실시하였다. 재질평가로서 표면경도와 치수안정성을 조사하였다. 압축률 50%로 열압밀화를 실시하여 비중 0.82~0.92의 고비중재를 얻을 수 있었다. 열압온도의 증가와 함께 표면경도는 증가하였으며, 온도 $160^{\circ}C$에서 30분간 열압밀화 한 시험편의 표면경도는 $23.6N/mm^2$로서 가장 높은 값을 나타내었다. 그러나 $180^{\circ}C$ 이상의 고온에서는 목재표면의 열분해에 의해 오히려 경도가 감소하였다. 열압온도의 증가는 치수회복률의 감소를 야기하였으며, 열압온도 $200^{\circ}C$에서는 14.9%로 가장 낮은 치수회복률을 나타내었다. 열압시간의 증가 또한 치수회복률 감소에 영향을 미치지만 열압온도에 의한 영향이 더욱 지배적이었다.

• Journal of the Korean Wood Science and Technology
• /
• 제42권5호
• /
• pp.563-570
• /
• 2014

Two transversely isotropic plasticity-based models for wood, derived from the standard compression properties and the embedment properties were investigated for suitability of application for bolted connections. It was found that the conventional connection models involving the compression properties were incapable of simulating the real behaviour of the connections because the compression properties provided too stiff foundation to represent embedding behaviour of wood under the bolt. However, wood foundation-based connection model that was newly developed using the bolt embedment properties showed good agreement with the actual behaviour of bolted connections.

• Journal of Plant Biology
• /
• 제33권4호
• /
• pp.285-292
• /
• 1990

In order to elucidate the formation of reaction tissues during the transition from primary to secondary growth, the developmental anatomy was conducted in the first internode of Ginkgo biloba seedling in horizontal position. The righting of the horizontal first internode took place at the middle portion and gradually proceeded to the base during the primary growth. Reaction tissues were formed corresponding to the righting movement in the horizontal first internode. During the transition from primary to secondary growth, compression wood was gradually developed on the lower side only. The anatomical features of compression wood also extended longitudinally to the lower side of the vertical portion where it coincided with the lower side of the horizontal first internode occurs acropetally from basal to apical portion. Eventually, some of the anatomical features of compression wood occurred at the primary growth. And the typical compression wood is gradually established during the secondary growth. On the other hand, the lower side tracheid and ray were longer and higher than those of the upper side in the horizontal first internode. However, difference in the width of ray was not observed between the lower and upper sides.