• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.644-654
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• 2019

참오동나무의 섬유방향기체투과성(gas permeability), 횡단방향 흡음율(sound absorption coefficient)과 음향투과손실(sound transmission loss)을 평가하고 열처리의 영향을 파악하고자 참오동나무 원반을 100, 160, $200^{\circ}C$로 열처리하고 기체투과성, 흡음율, 음향투과손실을 각각 측정하여 무처리 원반의 결과와 비교하였다. 그 결과, 두께 20 mm 참오동나무 원반의 섬유방향 기체투과성(specific permeability)은 무처리, 100, 160, $200^{\circ}C$ 열처리의 경우 각각 0.254, 0.279, 0.314, 0.452로 열처리에 의해 기체투과성이 약간 증가하였다. 두께 20 mm 무처리 참오동나무 원반의 50-6400 Hz 평균흡음율은 0.101이었으며 온도 100, 160, $200^{\circ}C$로 열처리한 목재의 50-6400 Hz 평균흡음율은 0.109, 0.096 그리고 0.106이었다. NRC (noise reduction coefficient) 는 각각 0.060, 0.067, 0.062 그리고 0.071 이었다. 두께 20 mm 무처리 참오동나무 원반의 50-6400 Hz 주파수범위에서 음향투과손실은 평균 36.93 dB이었다. 열처리에 의해 참오동나무 원반의 기체투과성과 흡음율은 열처리에 의해 그리고 열처리 온도 증가에 의해 약간 증가하였으나 증가정도는 미미하였다.

• Journal of the Korean Wood Science and Technology
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• 제44권6호
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• pp.890-896
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• 2016

Paulownia tomentosa is one of fast-growing wood species in Korea. In order to evaluate the solid bioenergy properties of Paulownia tree, this study examined the heating value, moisture content (MC), pH and proximate analysis of stem, branch, root, bark and leaf. The heating values of wood parts were slightly higher than those of bark and leaf, and that of branch was the highest among all the samples. The higher moisture content of bark and leaf referred to their lower heating value. Also, the pH of stem, branch and root was similar and lower than those of bark and leaf. The ash content of bark and leaf was much higher than that of wood parts, which is the one of the reasons for effect on the lower heating value and higher pH. While, the volatile matter content (VMC) of bark and leaf was lower than those of wood parts. The bark showed the highest fixed carbon content (FCC), while the FCC of stem was the lowest among all the samples. The obtained results are encouraging that the Paulownia tree could be totally utilized as alternative fuels for bioenergy production.

• Journal of the Korean Wood Science and Technology
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• 제10권3호
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• pp.3-3
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• 1982

• Journal of the Korean Wood Science and Technology
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• 제44권2호
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• pp.157-165
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• 2016

This study investigated several anatomical characteristics of Paulownia tomentosa roots. The root wood was separated into three parts from stem base (top, middle, and base) at different positions below ground. Qualitative anatomical data suggested that the growth rings in earlywood and latewood were structurally different. Furthermore, the root wood vessels were found having 2 to 3 radial multiples and they were appeared in the form of clusters. In addition, some sheath cells and septate axial parenchyma were observed. Regarding the quantitative anatomical characteristics, vessel and ray numbers per $mm^2$, as well as ray width and height differed significantly among the top, middle, and base rood wood parts. However, there were no significant differences in vessel diameters, cell wall thickness, and width and length of wood fibers among those parts. The crystallinity of the root top part was slightly higher than that of the middle and base parts. Furthermore, the vessel numbers, ray numbers, and ray width and height in the near pith (NP) area were higher compared to those in the near bark (NB) area. However, the fiber width and fiber length at NP were lower than those at NB. Overall, this study demonstrated some significant differences in the anatomical characteristics of the top, middle, and base parts of root wood from Paulownia tomentosa.

• 한국가구학회지
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• 제19권6호
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• pp.447-451
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• 2008

This study was carried out to know the difference of vapor transmission on the thickness of Paulownia wood(Paulownia tomentosa). The behavior of moisture transmission of wood thickness direction is generally estimated by vapor permeability and vapor transmission resistance. In general, Paulownia wood is known to use of inside material for furniture making, because of the excellent ability of vapor adsorption and/or desorption. Quarter sawing Paulownia wood material is prepared and the thickness is 6.0mm, 7.0mm, 8.0mm, 9.0mm, 10.0mm, respectively. The measurement of vapor transmission were conducted by the "cup method" in accordance with JIS(Japanese Industrial Standard) Z-0208. The experiment was made in the condition of 49.8mmHg vapor pressure difference and $40^{circ}C$ at constant temperature. From the experiment results, it was considered that Paulownia wood is very stable on moisture variation and any other material conditions. In this experiment we found that the vapor permeability and vapor permeance was reduced with the increase of wood thickness to vapor direction and vapor transmission resistance and specific vapor transmission resistance was increased with the increase of wood thickness to vapor direction. Besides moisture contents of adsorption and desorption side were about 5 percent and 14 percent, respectively. Mean value was 9.5 percent and about 10 percent in dry oven method. Moisture gradient was reduced with the increase of wood thickness for a small moisture difference of adsorption and desorption side.

• Journal of the Korean Wood Science and Technology
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• 제40권4호
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• pp.229-236
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• 2012

본 연구는 감마선 조사가 소나무(Pinus densiflrora), 느티나무(Zelkovas serrenata), 오동나무(Paulownia tomentosa)의 세포벽 열화, 셀룰로오스 결정화도, 휨 강도에 미치는 영향을 구명하기 위해 수행되었다. 각 목재 시편들을 100 kGy 선량의 감마선 조사 후 주사전자현미경(scanning electron microscope; SEM) 관찰 결과, 목재 세포벽 열화는 관찰되지 않았으며 휨 강도 역시 현저한 변화가 나타나지 않았다. 감마선 조사에 의한 셀룰로오스 결정화도 역시 유의한 변화가 관찰되지 않았다. 이러한 감마선에 대한 목재의 높은 안전성은 감마선 조사 기술을 재질손상 없이 목재를 가해 중인 균류와 충류 구제를 위해 적용할 수 있음을 의미한다.

• Journal of the Korean Wood Science and Technology
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• 제16권3호
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• pp.48-64
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• 1988

This study was carried out to investigate the free vibrational properties of traditional and replaceable species for sounding board, using piezoelectrical accelerometer and signal analyzer. In the study, the frequency equations of free-free beam carrying a concentrated mass in the transverse vibration and of free-mass beam in the longitudinal vibration were used. The results obtained were as follows. 1. Average values of dynamic modulus of rigidity of Korean commercial species measured were as follows. Paulownia tomatosa (Thunb.) Steudel: $5.590\times10^9\;dyne/cm^2$ Tilia amurensis Rupr.: $5.414\times10^9\;dyne/cm^2$ Macckia amurensis Rupr.: $10.044\times10^9\;dyne/cm^2$ Fraxinus mandshurica Rupr.: $8.876\times10^9\;dyne/cm^2$ Ulmus davidiana var.japonica Nakai: $8.677\times10^9\;dyne/cm^2$ Pinus rigida Miller: $6.33\times10^9\;dyne/cm^2$ Fraxinus rhynchophylla Hance: $4.666\times10^9\;dyne/cm^2$ 2. The ratio of dynamic transverse Young's modulus to dynamic modulus of rigidity, $E_T/G_{LT}$, was 24.922 for Fraxinus rhynchophylla Hance, which was the highest, 7.317 for Paulownia tomentosa (Thunb.) Steudel, which was the lowest among Korean commercial species measured. 3. The value of longitudinal dynamic Young's modulus was about 3.7% and 19.8%, respectively, higher than those of transverse dynamic and static Young's modulus. The value of transverse dynamic Young's modulus was about 15.5% higher than that of static Young's modulus. 4. Predicted value of MOR in terms of correlation coefficient by transverse dynamic Young's modulus was slightly higher than that of static Young's modulus, but no significance was found out. 5. Transverse dynamic Youne's modulus was $(2.002\pm0.288)\times10^{11}\;dyne/cm^2$ for Fraxinus mandshurlca Rupr., which was the highest, $(0.601\pm0.100)\times10^{11}\;dyne/cm^2$ for Paulownia tomentosa (Thunb.) Steudel, which was the lowest among Korean commercial species measured. The sound velocity of sitka spruce was 5,685 m/sec, which was the highest. 6. Internal friction of Paulownia tomentosa (Thunb.) Steudel was shown the lowest value among Korean commercial species, $(8.795\pm1.795)\times10^{-3}$, but was higher than that of sitka spruce, $(7.331\pm0.991)\times10^{-3}$. Internal friction was shown negative correlation with density and dynamic Young's modulus, respectively. 7. K value was affected largely by internal friction and was the highest, $2.225\times10^8$ for Paulownia tomentosa (Thunb.) Steudel and was the lowest, $0.550\times10^8$ for Fraxinus rhynchophylla Hance. K value of Paulownia tomentosa (Thunb.) Steudel was higher than that of sitka spruce and K values of melapi and cottonwood, which have been considered to be replaceable species with sitka spruce in the piano industry, were lower than those of Paulownia tomentosa (Thunb.) Steudel and mill amurensis Rupr.

• Journal of the Korean Wood Science and Technology
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• 제14권4호
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• pp.40-46
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• 1986

국내산(國內産) 16수종재의 철오염(鐵汚染), 알칼리오염(汚染) 산오염(酸汚染), 태양광(太陽光)에 의한 변색을 측정한 결과를 요약하면 다음과 같다. 1. 철오염(鐵汚染)이 심(甚)한 수종(樹種)은 일본잎갈나무, 신갈나무, 느티나무, 왕버섯나무등 이었고, 적은 수종(樹種)은 참오동나무, 리기다소나무등 이었다. 2. 국내산수종(國內産樹種)은 알칼리오염(汚染)이 적은 평이었고, 알칼리오염(汚染)이 낮은 수종은 젓나무, 음나무, 현사시, 고로쇠나무, 리기다소나무, 신갈나무, 자작나무, 왕벗나무, 느티나무, 이태리포플러, 잣나무, 참오동나무 등이었다. 3. 산오염(酸汚染)이 심(甚)한 수종(樹種)은 본(本) 실험(實驗)에서 사용재중(使用材中)에는 나타나지 않았고, 낮은 수종은 리기다소나무, 오동나무, 잣나무, 신갈나무, 음나무, 고로쇠나무 등 이었다. 4. 태양광(太陽光)에 의한 변색은 본(本) 실험(實驗)에서 사용(使用)한 공시재중(供試材中)에는 변색의 정도가 높은편으로서 변색이 심(甚)한 수종은 일본잎갈나무, 고로쇠나무, 참오도나무, 이태리포플러, 소나무, 아까시나무, 젓나무, 현사시, 느티나무, 왕벗나무, 리기다소나무 등이었으며, 태양광에 의한 변색이 낮은 수종(樹種)은 오리나무로서 국내산재 16수종이 태양광에 의한 변색의 정도가 높은 것이 특징이었다. 일반적(一般的)으로, 한국산(韓國産) 수종(樹種)은 태양광(太陽光)과 철오염(鐵汚染)에 의한 정도가 높은 편이었고, 알칼리오염(汚染)과 산오염(酸汚染)에 의한 변색은 낮은 편에 속하였다.

• Journal of the Korean Wood Science and Technology
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• 제25권2호
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• pp.61-66
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• 1997

Paulownia wood has been used as sound board for Korean traditional musical instruments such as Keomungo(Korean lute), Kayagum(twelve-stringed Korean harp) and Changgu(hour-glass shaped drum), etc. The acoustic properties of wood affected not only by dimensions but also by density and stiffness of wood. Due to inhomogeneity and hygroscopicity of wood. the acoustic properties of wood are inconsistent. To clarify the effect of moisture content and air dry density on acoustic properties, longitudinal vibration experiment was accomplished in 3 moisture content levels of 9.6, 11.1 and 12.5% and in 3 air dry density levels of 0.22, 0.25 and 0.28g/$cm^3$. The results were as follows: As the moisture content increased, the fundamental frequency. specific dynamic Young's modulus and sound velocity decreased, but the internal friction increased so that loss of energy increased. The values in damping of sound radiation were rapidly decreased at 12.5%. It meant that the damping of internal friction was larger than damping of sound radiation at high moisture content. As the air dry density increased, the fundamental frequency, specific dynamic Young's modulus and sound velocity increased, but the internal friction and damping of sound radiation decreased so that loss of energy decreased. And acoustic converting efficiency was hardly influenced by increasing air drying density.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.213-222
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• 2017

Heat treatment of wood is an attractive alternative environmentally-friendly treatment to add value of less valuable woods by improving color, dimensional stability, and natural durability. To improve the color properties of Korean white pine (Pinus koraiensis) and royal paulownia (Pauwlonia tomentosa), we treated the woods at $160^{\circ}C$, $180^{\circ}C$, $200^{\circ}C$, and $220^{\circ}C$ for 2 hours. Color change after heat treatment was evaluated using the CIE-Lab color system and survey was conducted to determine the consumer preferences towards color of heat-treated wood. Lightness ($L^*$) decreased with increasing temperature and the higher degree of change was obtained in royal paulownia. The red/green chromaticity ($a^*$) in both wood decreased after heat treatment at $160^{\circ}C$, and constantly increased after heat treatment at $180^{\circ}C$ to $220^{\circ}C$. Yellow/blue chromaticity ($b^*$) in Korean white pine tended to increase after heat treatment at $160^{\circ}C$, then decreased gradually afterwards. In royal paulownia, $b^*$ values linearly increased with increasing temperature. Overall color change (${\Delta}E^*$) increased with increasing temperature with higher degree obtained in royal paulownia. Samples with the clamps in both wood species showed lower degree of the change in $L^*$, $a^*$, b and ${\Delta}E^*$. The results of the consumer preferences test showed that the darker colors of heat-treated woods were more preferred by consumers compared to the lighter colors of untreated woods. Consequently, heat treatment could enhance the color properties of Korean white pine and royal paulownia woods for value added products.