• Journal of the Korean Wood Science and Technology
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• v.34 no.1
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• pp.79-85
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• 2006

Paulownia coreana Uyeki fruits were collected, extracted with acetone-$H_2O$ (7:3, v /v), fractionated with n-hexane, methylene chloride, and ethyl acetate, then freeze dried to give some dark brown powder. The ethyl acetate soluble mixture was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Spectrometric analysis such as NMR and MS including TLC were performed to establish the structures of the isolated compounds. From the ethyl acetate fraction, one phenolic acid (I) and five flavonoids (II~VI) and were isolated and elucidated. The antioxidative activities were tested on the isolated compounds, crude and fractionated extractives by DPPH radical scavenging method. The result showed that caffeic acid, kaempferol, luteolin, quercetin and the EtOAc soluble fraction exhibited higher activities than those of ${\alpha}$-tocopherol and BHT.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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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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• v.14 no.2
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• pp.13-20
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• 1986

The effect of heat treatment on the dynamic viscoelasticity of the woods of Picea sitchensis and Paulownia coreana which have been for musical instruments was investigated. The treatment was made in a temperature range of 60-180$^{\circ}C$ for periods of 3 hours to 24 hours. The results obtained are summarized as follows: Moisture absorption decreased with increasing temperature. Dynamic Young's modulus decreased with increasing temperature and hours. Dynamic viscoelasticity decreased with increasing moisture content, but internal friction increased with increasing amount of moisture content.

• Journal of Forest and Environmental Science
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• v.22 no.1
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• pp.13-17
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• 2006

Approximately each 5 kg dried Paulownia coreana leaves, seeds, outer barks, inner barks and wood were ground, extracted with acetone-$H_2O$ (7:3. v/v). concentrated under reduced pressure and successively fractionated using n-hexane. $CH_2Cl_2$, EtOAc and $H_2O$ on a separation funnel. Each fraction was then freeze dried and weighed. The extraction yield of each sample was investigated and the yield of inner barks was the highest, while the wood was the lowest. Antioxidative activities of crude extracts, precipitates and partitioned fractions were evaluated by DPPH radical scavenging method. The results indicated that all EtOAc soluble fractions, including some of $H_2O$ soluble fractions, showed significantly high antioxidative potential compared with ${\alpha}$-tocopherol and BHT used as controls.

• Journal of the Korean Wood Science and Technology
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• v.38 no.2
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• pp.101-107
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• 2010

Heat treatment was performed to improve sound absorption properties for four tree species; Tulip tree, Korean Paulownia, Red pine and Costata birch, at temperature of $175^{\circ}C$ and $200^{\circ}C$under vacuum condition. Sound absorption properties of two kinds of boards, which were in radial and tangential sections, were measured under a frequency range of 100 to 3200 Hz by the two microphone transfer function method. It was found that sound absorption properties were increased by heat treatment and the efficiency was higher at $200^{\circ}C$ than that at $175^{\circ}C$. Even Costata birch had a little effect on low temperature of $175^{\circ}C$, $200^{\circ}C$ heat treatment for sound absorption property, the efficiencies of sound absorption were 14, 19%, respectively. The efficiencies of sound absorption ranged 22 to 120% for heat-treated Tulip tree, Korean Paulownia.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.884-887
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• 2000

In the present industry, there is not only the cutting of iron metal, but also the cutting of alloy aluminum, brass and plastic to wood(Paulownia). A variety of material is used and these industry is made need of the cutting material but lots of experiments processing is not enough at the moment. At this point, our team processed the basic experiment about influencing of Feedrate and Backrake angle of bite concerned to manufacture in the turning of non-iron metal. Generally speaking, we recognized that there was occurrence of increase of Surface Roughness with increasing of cutting angle in the non-iron metal, but in the cutting of wood we knew, there was special change with change of cutting angle

• Journal of the Korean Wood Science and Technology
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• v.16 no.3
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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 Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.39-44
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• 2003

In the present industry, there are necessary to cut not only iron metals but also non-ferrous metals such as aluminum, brass, plastic and wood(Paulownia) therefore it had been made the studies of non-ferrous metals by many scientists. The purpose of this study is to conduct the basic experiment about influencing of the feedrate adjustment and the change of the side rake angle at turning of non-ferrous metals. As the results, the surface roughnesses and Cutting force adjustments were on the decrease with a side-rake angle and feedrate diminution in the case of the plastic, brass, aluminum, and paulownia.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.1-6
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• 2001

In the present industry, there are necessary to cut only iron metals but also non-ferrous metals such as aluminum, brass, plastic and wood(Paulownia), therefor it had been made the studies of non-ferrous metals by many scientists. we hope this kind of study will continue. The purpose of this study is to conduct the basic experiment about influencing of the feedrate adjustment and the change of the side rake angle at turning of non-feerous metals. As the results, the surface roughnesses were on the decrease with a side-rake angle and feedrate diminution in the case of the pastic, aluminum, and paulownia.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.929-934
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• 1997

In the present industry, there are necessary to cut not only iron metals but also non-ferrous metals such as aluminum, brass, plastic and wood(Paulownia).therefore it had been made the studies of non-ferrous metals by many scientists. we hope this kind of study will continue. The purpose of this study is to conduct the basic experiment about influencing of the feedrate adjustment and the change of the side rake angle at turning of non-ferrous metals. As the results, the surface roughnesses and Cutting force adjustments were on the decrease with a side-rake angle and feedrate diminution in the case of the plastic, brass, aluminum, and paulownia