• Journal of the Korean Wood Science and Technology
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• v.14 no.4
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• pp.40-46
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• 1986

Change of color of woods is a trouble frequently found in decorative wood products. In this paper, studies were carried out on discoloation sensitivities of wood specimens to iron (0.1%, $FeCl_3{\cdot}6H_2O$), alkali (pH12.0, NaOH), acid (pH 1.0 $C_2H_2O_4$) and exposing to sunlight (40 hrs.). Four soft-woods and eleven hard-woods grown in Korea were used in this test. The results obtained were as follows: 1. In iron stain, strong discolored wood species were Larix leptolepis, Quercus mongolica. Zelkova serrata and Prunus yedoensis, and light discolored were Paulownia lomentosa and Pinus rigida. 2. In alkali stain. light discolored wood species were Abies holophylla, Kalopanax pictum, Populus ${\times}$ albaglandulosa, Acer mono, Pinus rigida, Pinus densiflora, Quercus mongolica, Betula platyphylla var. japonica, Prunus yedoensis, Zelkova serrata, Populus euramericana, Pinus koraiensis and Paulownia tomentosa, but there was no wood species of strong discolored compared with the color difference values of other reports. 3. In acid stain, light discolored wood species were Pinus rigida, Paulownia tomentosa. Pinus koraiensis, Quercus mongolica, Kalopanax piclum and Acer mone, but there was no strong discolored species compared with the color difference values of other reports. 4. In exposing to sunlight, strong discolored species were Larix leptolepis, Acer mono, Paulownia tomentosa, Populus euramericana, Pinus densijlora, Robinia pseudoacacia, Abies holophylla, Populus ${\times}$ albaglandulosa, Zelkova serrata, Prunus yedoensis and Pinus rigida, and light discolored was Alnus japonica. In general, it was shown that Korean wood species were susceptible to change of color by exposing to sunlight and iron stain compared with by alkali stain and acid stain.

• Journal of Conservation Science
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• v.24
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• pp.75-83
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• 2008

In order to assess antifungal activity of a wooden storage box, which was made of Paulownia tomentosa and used for keeping ancient documents, antifungal activity of volatile organic compounds emitted from the box was investigated along with qualitative analysis on major substances of the compounds. After collecting floating microorganisms inside air tester, the fungal activity was assessed by counting the number of colonies growing on TSA media. Compared to the control which collected 85 colonies from outdoor, 72 colonies were observed showing reduction rate of 14.82%. Through GC/MS and TDS system analysis, limonene was detected from the volatile organic compounds as characteristic features. When the fungal activity was assessed through fumigation by adding natural biocide BI and BII containing eugenol and anethole as major substances, both biocides showed a strong fungal activity with respectively 92.6%(inside the box) and 99.9%(outdoor) of reduction rate. Although these results didn't clarify antifungal activity of the volatile organic compounds emitted from the Paulownia-wood storage box and their functional components, it was at least confirmed that there is application possibility of natural biocide to use for preservation of ancient documents with increased efficiency in controlling pests of wooden storage boxes.

• Journal of Korean Society of Forest Science
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• v.83 no.1
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• pp.1-5
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• 1994

Sixteen kinds of piercing-sucking mouth type insects were observed at witches'-broom diseased paulownia (Paulownia tomentosa) trees. Among ten insect species tested, a leafhopper, Empoasca sp., transmitted paulownia witches'-broom mycoplasma-like organism(PWB-MLO) to periwinkle(Catharanthus roseus) plant. Adults of this leafhopper were collected from PWB-diseased paulownia trees. The leafhpoppers were allowed to feed on the PWB-infected paulownia trees for three weeks to acquire PWB-MLO. These insects were then transferred to healthy seedlings of paulownia and periwinkle plants for inoculation-feeding. About 30-40days after the inoculation, "little-leaf" symptoms developed on periwinkle plants, but no symptoms developed on paulownia seedlings. MLO infection in the diseased periwinkle tissue was diagnosed by fluorescence microscopy. MLOs were observed in the sieve tubes by electron microscopy, proving the insect transmission of PWB-MLO.

• Journal of the Korean Wood Science and Technology
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• v.19 no.1
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• pp.71-80
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• 1991

This study was carried out to investigate replaceable species with the conventional sounding board sitka spruce. by comparing the dynamic properties such as density, dynamic Young's modulus and internal friction Dynamic Young's modulus. internal friction of longitudinal and radial direction measured in free mass-free boundary condition for facile vibration analysis and measured by forced vibration method. Dynamical properties of four species were measured on squared plate specimen that the four edges were hung vertically by threads and driven magnetically through an iron piece glued on the specimen, by the use of condenser microphone as vibration transducer, and analyzed by FFT analyzer. The results obtained were as follows: 1. Chaldni method using aluminum powder was proper to identify the vibration mode in the plate vibration and it was possible to verify the resornance mode. 2. It was considered that it was necessary to investigate the influence of adhesive part on the plate vibration when the sounding board was made by two or three small board adhesion. 3. It was considered that plate vibration method, which was a superior to the vibration test of beam, was suitable for selecting suounding board because dynamic Young's modulus and internal friction show different order according to longitudinal and radial direction. 4. Paulownia tomentosa Thunb.) Steudel has been considered to be replaceable species with sitka spruce because it has high dynamic Young's modulus compared with low density, low internal friction, and K value of Paulownia tomentosa (Thunb.) Steudel is greater than that of sitka spruce.

• 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.45 no.2
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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.

• YAKHAK HOEJI
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• v.37 no.3
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• pp.286-289
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• 1993

UV and high performance liquid chromatographic methods for the quantitative analysis of methyl 5-hydroxy-dinaphtho [1,2-2',3'] furan-7,12-dione-6-carboxylate(MHDDC) in urine and blood were developed. The correlation coefficients of the calibration curves of MHDDC in chloroform, methanol and dioxane solution were 0.999, 0.997 and 0.998, respectively. MHDDC was resolved within 15 min and had a detection limit of 2-5ng at S/N=3 by using a reversed-phase column with two solvents (MeOH, HAc).

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.511-526
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• 2018

Effects of heat treatment on the characteristics of Royal paulownia (Paulownia tometosa) wood were investigated. The results were compared with those of Suwon silver poplar (Populus tementiglandulosa) and Korean red pine (Pinus densiflora) woods. The wood samples of the three species were treated at $160^{\circ}C$, $180^{\circ}C$, $200^{\circ}C$ and $220^{\circ}C$ in an electric furnace for 2 hours. The changes of color, density, mass loss, and relative crystallinity were investigated before and after heat treatment. The lightness ($L^*$) decreased rapidly from $200^{\circ}C$ in all species. There were no change in red-green chromaticity($a^*$) and yellow-blue chromaticity($b^*$) of Royal paulownia and poplar woods with increasing temperature. Whereas, yellow-blue chromaticity($b^*$) of Korean red pine wood decreased sharply from $200^{\circ}C$. Royal paulownia wood showed appreciable color change(${\Delta}E^*$) after heat treatment above $180^{\circ}C$. Poplar and pine woods, however, presented significant color change from $160^{\circ}C$. Color change of the three wood species increased rapidly with increasing temperature. Mass loss of the three wood species by heat treatment was the highest in the Royal paulownia wood and the lowest in the pine wood. Mass loss and relative crystallinity increased and density decreased slightly with increasing temperature. Consequently, it is revealed that Royal paulownia wood showed considerable differences in the temperature of color change, weight loss and change of relative crystallinity compared to the other wood species.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.760-766
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• 2016

This study explored the effects of heating temperature and laminae thicknesses on the time required to heat the center of air-dried Paulownia tomentosa, Pinus sp., Abies sp., and Larix sp. laminae to $56^{\circ}C$, which is a minimum core temperature of wood packaging materials defined by ISPM 15 standard, and maintain for 30 minutes in dry heat treatment schedule. Heating times were different among wood species and were Pinus sp. ${\geq}$ Abies sp. > Paulownia tomentosa > Larix sp. in decreasing order. The differences in heating times of some species were significantly different statistically, but were not different enough in practical terms to warrant heating four species separately. Heating times decreased as heating temperature increased and followed approximately power-function relationship. Also, heating times increased linearly with increasing laminae thickness. These relationships make it possible to calculate intermediate heating times relative to experimentally observed heating times. The results of this study will serve as a guideline for heat sterilization of Chinese laminae species to meet heat treatment requirements for protection against invasive pests.

• Journal of Korean Society of Forest Science
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• v.80 no.2
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• pp.232-236
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• 1991

The efficacy of berberine sulphate, a fluorochrome having binding properties with both DNA and RNA, was investigated for the detection of mycoplasma-like organisms(MLOs) in jujube(Zizyphus jujuba), paulownia(Paulownia tomentosa), mulberry(Morus alba) trees and periwinkle (Catharanthus roseus) plant. When examined under fluorescence microscope, berberine sulphate-stained sections of diseased samples showed distinct MLO-specific fluorescent particles in the phloem area, while such fluorescence was absent in the healthy ones. This staining technique was proved to be a very accurate method for the diagnosis of MLO infections in woody and herbaceous plants. Furthermore, the cheap and easy procedure could be used to test a great number of samples on MLO infections with reliability and rapidity.