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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Wood Science and Technology
Journal Basic Information
Journal DOI :
The Korean Society of Wood Science Technology
Editor in Chief :
Volume & Issues
Volume 26, Issue 4 - Dec 1998
Volume 26, Issue 3 - Sep 1998
Volume 26, Issue 2 - Jun 1998
Volume 26, Issue 1 - Mar 1998
Selecting the target year
Measurement of Equilibrium Moisture Content of Wood at High Temperatures and Vapor Pressures
Lee, Weon-Hee ; Abe, Hisashi ; Kuroda, Naohiro ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 1~5
In this study, it was examined the method to estimate equilibrium moisture content(EMC) at high vapor pressures and high temperatures above
. The material used for the experiment was Sugi(Cryptomeria japonica). EMC was investigated at temperatures ranging from
and under saturated vapor pressures above 1 atm. The correlation between temperatures and vapor pressures have a good agreement with those observed by thermocouple and pressure gauge in the air state of autoclave, respectively. A sensitivity of quartz spring was 65mm/g. Moisture content(MC)s calculated from the quartz spring elongation by vapor sorption showed a good agreement with MCs by oven-dried method. Using this system, it was found that EMC at high vapor pressures and high temperatures above
were higher than EMC of wood in 1 atm pressure conditions. With this system, therefore, it was concluded that the EMCs of wood and wood-based materials at high temperatures were able to be evaluated.
Bending Properties and Recommened Design Criteria for Domestic Softwood with Notch
Oh, Sei-Chang ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 6~12
Test results of domestic softwood lumber were presented to examine the notch effect of beams and compare to present AIJ(Architecture Institute of Japan) formula in notched wood member especially positioned in bottom side (tension side) of a beam. Notched lumber was tested under following condition : each specimen supported simply, and subjected to third-point loading at points of 1/3 of the span length. Notch was located opposite side to loading direction and notch depth were 1/6, 1/4, 1/3 of beam depth. Deflection and load were measured by digital dial guage each in 25kgf increment. Bending test results were as follows; Mpro/Mmax range (proportional and maxium bending moment ratio in notched beam) was 0.5 - 0.65. It was considered that maxium bending moment was about 1.5 times to proportional bending moment in notched beam and showed same tendency in the test result of ordinary wood specimens. AU standard formula for the tension side notch, Mmat = 0.6
), the constant 0.6 was suitble for notch ratio(notch depth to beam depth) 1/6, but this ratio for 1/4, and 1/3 was not. So it is preferable to accept smaller value than 0.6 for notch ratio more than 1/3. These experiment results showed critical effect in tension side notched wood beam especially in greater than notch ratio 1.3 of wood beam. From the above results, it is recommened to revise design formula adoptable to domestic wood constructon member with tension side notched member.
Stress Relaxation of Wood and Theoretical Models under Tensile and Bending Strain
Jang, Sang-Sik ; Kang, Chun-Won ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 13~19
Stress relaxation tests have been performed under five different tensile strain levels and five different bending strain levels. Three different theoretical models have been developed based on four-element Burger's model, viscoelastic theory and viscous-viscoelastic theory. Experimental data were used to obtain parameters of the models and to verify accuracy of the models. Among the three theoretical models developed in this study, three-integral model (Model 3) based on viscous-viscoelastic theory showed the most exact estimations of stress relaxation under both tensile and bending strains and their correlation coefficients were greater than 0.99 for all the strain levels. Model 1 showed little initial stress relaxation. Model 2 showed excessive initial relaxation and, then, no relaxation after about 20 minute of strain application. Stress retention under strain decreased as strain increased, which means increased stress relaxation as strain increases. When the strain level was less than proportional limit, the effect of strain level on stress relaxation was not clearly shown. However, this effect was increased as strain level increased when strain level was greater than proportional limit.
Variation of Crystalline State in a Stem of Chamaecyparis obtusa E.
Kim, Nam-Hun ; Lee, Ki-Yeong ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 20~25
Radial variation of crystalline state in a stem of Chamaecyparis obtusa E. was examined by x-ray diffraction analyses. Relative crystallinity and degree of crystallite orientation showed significant differences between juvenile and adult wood. That is, Relative crystallinity increased with increasing the age from pith to about 20th annual ring, after which it reached a more or less constant value. On the other hand, degree of crystallite orientation decreased outward from pith to about 10 years and presented almost a constant value thereafter. Crystal width by Scherrer's equation did not show any significant differences between juvenile and adult wood. Therefore, it was considered that crystallinity index and degree of crystallite orientation by x-ray diffraction method could be used for evaluating wood quality.
Effects of Double Surfaces Finishing on Acoustical Properties of Soundboard for Traditional Musical Instruments
Jung, Hee-Suk ; Yoo, Tae-Kyung ; Kwon, Joo-Yong ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 26~33
Acoustical properties of chestnut and paulownia woods have been determined in four film thicknesses of oriental lacquering and cashew varnishing on double surfaces of soundboard to elucidate effects of finishing. Accelerometer was attached to the specimen at one third position from one end, and specimen was hit by the impact hammer at one third position from opposite end. Data were processed by vibration analyzer. The ratio of axial-to-transverse sound velocity of untreated specimens of chestnut and paulownia were 3.25 and 5.34, respectively. Natural frequency, specific Young's modulus, acoustical coefficient, sound velocity, damping of sound radiation(DSR) and acoustical converting efficiency(ACE) decreased by oriental lacquering and cashew varnishing for both species. Damping of internal friction of chestnut decreased by oriental lacquering and cashew varnishing, but that of paulownia increased. Natural frequency. specific Young's modulus, acoustical coefficient, sound velocity, and DSR decreased with increased film thickness of both finishing materials. However, damping of internal friction and ACE showed irregular tendency with increased film thickness. Acoustical properties of cashew varnished chestnut specimen were better than those of oriental lacquered specimen. Acoustical properties of oriental lacquered paulownia specimen were better than those of cashew varnished specimen.
Prediction of Microwave Drying Curves for Various Hardwoods and Softwoods
Kang, Ho-Yang ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 34~42
Three hardwood (ash, alder and black locust) and three softwood (Japanese red pine, radiata pine and Western hemlock) specimens were dried in microwave(MlW) oven and their drying rates were obtained. Their specific permeabilities were also measured by using a modified liquid permeability measuring device. The correlation between the M/W drying rates and permeabilities of six species were statistically analyzed. It was revealed that within a species there is a logarithmic relationship between the M/W drying rates and average moisture contents and that among species there is a linear relationship between the M/W maximum drying rates and the average specific permeabilities. A exception was Western hemlock, which was of low permeability and of high drying rate. A Me-time equation, which showed a good agreement with the actual data, was derived. Thus using this equation the moisture contents of wood and the drying end points of M/W drying could be predicted. Infrared images of the thermal distribution in wood were illustrated.
Development of Urethane Foams for Planting Media from Woodwastes
Cho, Nam-Seok ; Seo, Won-Sung ; Han, Gyu-Seong ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 43~49
The availability of large quantities of waste woods provides an impetus for investigating woody biomass potential uses. Polyurethane (PU) foams are prepared with reacting isocyanates and polyols, and are used. in various industry fields. Thus, lignocellulosic waste raw-materials are proposed as replacement for synthetic polyol to PU foam formulation. In this study PU foams were manufactured from liquefied woods, methanediisocyanate(MDI), catalyst, foaming stabilizer, and viscosity aids. The polyol content, isocyanate.hydroxyl group (NCO/OH) ratio, and water content were varied to evaluate their effects on the foaming and water absorption of the PU foams. Less than 400 Molecular weight. of polyethylene glycol(PEG) and 1 to 3 solvent to woody raw-material ratio were desirable for liquefying woody materials. Liquefying rate was increased with more than 3 % addition of inorganic and organic catalysts and raising reaction temperature more than
. Addition of starch enhanced liquefying of woody materials. Fourty percents of starch resulted in about 90% liquefying rates. Foaming rates were increased with increasing moisture contents of liquefied wood. Moisture contents of 0.6% resulted in 5 time-foaming rates, and seven percents of moisture contents more than 30 time-foaming rates. But, an increase in water content may result in a decrease in cross-links between wood polyol and isocyanate, because the NCO/OH ratio is constant. Increasing moisture contents have significantly decreased density of PU foams. The optimum water content should be about 2.5% or less in this adopted condition.
Development of Rice Hull Insulation Board using Urea Formaldehyde Resin
Lee, Hwa-Hyoung ; Kang, Chun-Won ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 50~55
This study was carried out to develop low density board made of rice hull which needs proper use. Urea formaldehyde adhesive(UF) was used. The raw materials were the mixtures of the rice hulls from IllFum, DongGin, ChuChong, etc. The physical and mechanical properties of rice hull insulation board were examined. The results are as follows : For the thickness of 15mm of the low density rice hull board bonded with UF resin, proper manufacturing conditions were
of hot pressing temperature with thickness bar for optimum density, 12 percent of resin solid contents of rice hull ovendry weight, and 20 minutes of hot pressing time. These conditions meet Korean standards(KS 3201-1982) in relation to free formaldehyde emission, bending strength, water absorption and heat resistance.
Oleuropein and Ligstroside from the bark of Fraxinus rhynchophylla
Lee, Sang-Keug ; Ham, Yeon-Ho ; Bae, Young-Soo ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 56~60
The bark of Fraxinus rhynchophylla, one of ash trees grown in domestic, was collected, extracted with acetone-
(7:3, v/v) and freeze dried to give 50g of ethylacetate soluble powder. A portion of the freeze dried powder was chromatographed on a Sephadex LH-20 and a TSK 40F column using a series of aqueous methanol and ethanol-hexane mixture as eluents. The extractives contained a large amount of coumarin derivatives in addition to a small amount of ester compounds such as ligstroside and oleuropein which have not been isolated from this tree species yet. Some spectrometric analyses such as NMR and FAB-MS including TLC were performed to identify the structures of the isolated ester compounds.
Extractives of Magnolia kobus DC. var. borealis Sarg. - Lignans from the each tissue -
Kim, Yun-Geun ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 61~70
Xylem, bark and flower buds of Magnolia kobus DC. var. borealis Sarg. were extracted with ethanol. And then the ethanol extracts were fractionated with diethyl ether. The lignans structure of the diethyl ether fractions were determined by spectroscopic methods. The results are summarized as follows : 1. Three compounds, aschantinn(X-I), yangambin(X-II), (-)syringaresinol(X-III), tetrahydrofurofuranoid lignans were isolated from the xylem. 2. Five compounds were isolated from the bark. These are all tetrahydrofurofuranoid lignans, aschantin(B-I), yangambin(B-II), medioresinol(B-III), (+)syringaresinol(B-IV), and tetrahydrofuranoid, kobusinol B(B-V). 3. Three tetrahydrofurofuranoid lignans, kobusin(F-I), aschantin(F-II), yangambin(F-III) were isolated from the flower buds. 4. Isolated lignans from the each tissue were two types of tetrahydrofurofuran type and tetrahydrofuran type. 5. The tetrahydrofurofuranoid lignans were five compounds such as kobusin, aschantin, yangambin, medioresinol, and syringaresinol, while the tetrahydrofuranoid lignans was kobusinol B. 6. Most of these lignans were substituted with the methylenedioxy or methoxyl groups.
Isolation of Diterpene from Larix leptolepis Gorden
Hwang, Byung-Ho ; Zhao, Julan ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 71~77
To elucidate chemical structure of the wood extractive, wood meal of Larix leptolepis Gorden was extracted with 95% ethanol for 72 hours. The extract was fractionated with organic solvents such as n-hexane, chloroform, diethylether, and ethyl acetate. From the hexane somble fraction of the extractives, a new diterpene compound was isolated and identified as 6-acetoxymanool or 13-hydroxy-8(17), 14-labddienyl-6-acetate by IR,
-NMR and Mass spectrometry.
Antifungal Activity of the Extracts of Zanthoxylum Schinifolium Sieb. et Zucc. against Dermatophytes
Min, Kyeong-Heui ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 78~85
The antifungal activity of methanol extracts against dermatophytes was the highest at root-bark methanol extract, and the highest inhibitory effect was revealed in petroleum ether fraction of root-bark methanol extract. Compound I and compound II with significant antifungal activity were isolated from the fractions by silica gel column chromatography. As a result of the instrumental analyses, compound I and compound II were already known alkaloids. Compound I was identified as 4-methoxyfuro[2,3-6]quinoline (dictamnine ;
) and compound II was identified as 4-methoxy-lmethyl-2(1H)-quinolinone (
). The MIC of compound I against T. mentagrophytes and T. rubrum was
and the MIC of compound II against the same fungi was
Study on Filtration Characteristics of Wood Pulp and Non-Wood Fiber
Cho, Jun-Hyung ; Han, James S. ; Lee, Beom-Goo ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 86~91
The drainage was used to determine the specific filtration resistance for wood and non-wood fibers. The drainage rate is also affected by factors that can be changed on consistency, pressure drop across the mat, basis weight, additives, and viscosity. Recent development of theoretical studies in flow through porous media and filtration operation emphasize the urgent need for more accurate data for porosity and specific filtration resistance. This study was investigated to determine specific filtration resistance of Hw, Sw-BKP and Kenaf fiber by filtration experimental. Freeness levels selected were 150,250,and
CSF. The average specific filtration resistance decreased as freeness increased and resistance of Sw-BKP was greater than that of Hw-BKP. The filtrate and porosity increased and specific filtration resistance decreased as particle size of fiber increased.
Evaluation of the Performance and Formaldehyde Emission Level of Particleboards Bonded with Urea-Formaldehyde Resins
Oh, Yong-Sung ;
Journal of the Korean Wood Science and Technology, volume 26, issue 4, 1998, Pages 92~97
Four urea-formaldehyde (UF) resins were synthesized as a particleboard (PB) binder with the four different initial formaldehyde/urea mole ratio and the final mole ratio of 1.15. The UF resins were characterized according to the standard method of resin adhesive analysis. PBs were manufactured using liquid UF resins at 5 minutes press time and 6% resin solids levels on an ovendry particle weight basis. A total of 20 PBs was fabricated for 5 panel replication per UF resin types. The panels were tested for physical strength properties per the procedure ASTM D 1037. The formaldehyde emission levels from the PBs bonded with the UF resins were tested according to 2-hour desiccator test method ASTM D 5582. There were no significant differences among UF resin types for internal bond strength of PBs. But there were significant differences among UF resin types for formaldehyde emission level of PBs. The results showed that the formaldehyde emission level was influenced by the UF resin types without reducing the adhesive performance.