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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
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Volume & Issues
Volume 41, Issue 6 - Nov 2013
Volume 41, Issue 5 - Sep 2013
Volume 41, Issue 4 - Jul 2013
Volume 41, Issue 3 - May 2013
Volume 41, Issue 2 - Mar 2013
Volume 41, Issue 1 - Jan 2013
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X-ray Computed Tomography on Larger Diameter Timber than Digital Detector
Kim, Chul-Ki ; Lee, Jun-Jae ; Oh, Jung-Kwon ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 385~391
DOI : 10.5658/WOOD.2013.41.5.385
X-ray computed tomography is a very powerful nondestructive technique in safety inspection of historic timber building. But, in field, various testing condition makes it difficult to carry out X-ray CT testing. Limited size in X-ray digital detector is one of the problems. In this study, a pitch pine disk with two holes was used to know how imperfection in X-ray projection affects CT image resolution. Using various number of projections, CT image was reconstructed by filtered back projection method, and then it was investigated how many projection is required to identify the holes in different location. Two artificial holes could be differently detected according to their location in cross section of specimen. One hole in center part of specimen was identified using more than 9 radiographs, but the other one which located in outer part of cross section could not be detected until more than 36 projections were used. Even though there is data missing in outer part of cross section due to limited size of detector, the center part of CT image could be reconstructed well and the resolution of outer part became higher with increase of the number of projections. For field application, the number of projections for CT image reconstruction needs to be decided with consideration of another nondestructive testing and the location of interest.
Effect of Test Zone Selection for Evaluating Bending Strength of Lumber
Pang, Sung-Jun ; Lee, Jun-Jae ; Oh, Jung-Kwon ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 392~398
DOI : 10.5658/WOOD.2013.41.5.392
This study investigated the effect of test zone selection for evaluating bending strength of visually graded lumber. This will contribute to the understanding of two different methods under different standards. In method I, the major defect was randomly placed in the test specimen. In method II, the major defect was randomly placed in the maximum moment zone (MMZ). The results showed that the method II is more accurate for reflecting the effect of defects governing the grade of lumber. Unless the maximum strength-reducing defect (MSRD) is placed in MMZ, the evaluated value would be higher than that of MSRD. For evaluating the modulus of rupture (MOR) of visually graded lumber in test set-up of Method I, the Eq. (5) needs to be considered.
Utilization of Light Microscopy and FFT for MFA Measurement from Unstained Sections of Red Pine (Pinus Densiflora)
Kwon, Ohkyung ; Lee, Mi-Rim ; Eom, Chang-Deuk ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 399~405
DOI : 10.5658/WOOD.2013.41.5.399
This study demonstrates the utilization of light microscopy and Fast Fourier Transform-Peak Finding (FPF) method for microfibril angle (MFA) measurement from unstained sections of red pine (Pinus densiflora). To obtain an image with optimal contrast and resolution for MFA measurement, effects of numerical aperture (NA) of condenser lens and color filters were investigated. About 60% of NA of the maximum condenser NA produced an image with optimal contrast, but a color filter with short wavelength range (DAPI) created images with improved resolution. Manual angle measurement and the FPF method were applied to the image with optimal contrast for MFA measurement. The experimental results from the FPF method were considered to be more repeatable and less subjective than those from the manual angle measurement.
Tree-Ring Dating of Coffin Woods Excavated from Shinnae-dong in Seoul, Korea
Lee, Kwang-Hee ; Son, Byung-Hwa ; Park, Won-Kyu ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 406~414
DOI : 10.5658/WOOD.2013.41.5.406
This study aims to date wooden coffins excavated from graves in Shinnae-dong, Seoul, South Korea, using dendrochronology. The species of woods used to make the coffins were identified as Pinus densiflora S. et Z., one of the major conifers in Korea. Of 12 graves, 10 were successfully dated using various red-pine chronologies of South Korea. Due to the absence of the last-formed tree ring before felling, the number of sapwood rings, used to obtain likely cutting dates, had to be estimated. The terminus post quem for two coffins without plaster frames were AD 1548 and AD 1571, respectively. Eight coffins with plaster frames yielded estimated dates from AD 1664 to AD 1799. The tree-ring dates indicated that the coffins with plaster frames in Shinnae-dong were constructed approximately 100 years later than those without plaster frames.
Predicting Moment Carrying Capacity of the "sagae" Connection Using the Finite Element Method
Jeong, Gi Young ; Park, Moon-Jae ; Park, Joo-Saeng ; Lee, Sang-Joon ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 415~424
DOI : 10.5658/WOOD.2013.41.5.415
The goal of this study is to analyze the effects of geometries of mortise and tenon on moment carrying capacity of the "sagae" connection. Effects of different tenon widths, mortise depths of connection from the top and bottom beams on stress distribution were investigated using the finite element method (FEM). Critical normal and shear stresses occurred at the reentrant corner from the mortise of the bottom beam. The maximum moment carrying capacity of the sagae connection from the FEM was validated from the results of experimental test. Maximizing moment carrying capacity of the sagae connection was found when the tenon width and mortise depth from the two beams were 40 mm and 60 mm, respectively.
Determining Shear Modulus of 3-ply Laminated Veneer Lumber by Uniaxial Tension Test
Oh, Sei-Chang ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 425~431
DOI : 10.5658/WOOD.2013.41.5.425
Estimation equations of shear modulus in the plane of laminated veneer lumber (LVL) were compared each other through uniaxial tension test results. The equations - basic elastic equation in the dimensional orthotropic case, Hankinson's formula and empirical equation proposed by Salikis and Falk, were applied to determine the elastic constants at various angles to the grain, which were needed for determination of shear modulus. Tensile elastic modulus of LVL predicted from these equations were compared with test data to evaluate the accuracy of the equation. Tensile elastic modulus rapidly decreased at orientations between 0 and 15 degrees and elastic modulus at grain angles of 15, 30, and 45 degrees overestimated in the presented equations. But the proposed equation by Salikis and Falk showed better prediction, especially at 30, and 45 degrees. This proposed formula would be more useful and practical for estimating of shear modulus of wood composites like LVL to minimize the effect of Poisson's ratio term.
Evaluation of Allowable Bending Stress of Dimension Lumber; Confidence Levels and Size-adjustment
Pang, Sung-Jun ; Lee, Jun-Jae ; Oh, Jung-Kwon ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 432~439
DOI : 10.5658/WOOD.2013.41.5.432
The aim of this study was to investigate the processes for evaluating the allowable bending stress. The confidence levels and the size-adjustment in standards were reviewed with experimental data. The results show that, (1) KS F 2152 was more strict than others overseas standards due to the higher confidence level. The 5% NTL of bending strengths by a method in KS F 2152 were lower than the overseas standards and more specimens were required for evaluating the structural properties according to KS F 2152. (2) Due to the absence of size-adjustment method in domestic standards, the specified size and the exponential parameters on the size-adjustment equation were reviewed by size factors. The specified size (width: 286 mm, length: 6096 mm), and the exponential parameters (w: 0.29, l: 0.14) will be suitable for developing the allowable bending stress in domestic standard. (3) The size adjusted allowable bending stresses of No. 2 grade Korean pine were lower than the allowable stresses tabulated in KBC even though less strict method (75% confidence level) to calculate 5% value was used. The allowable stresses tabulated in KBC are needed to be reviewed by continuous experimental data.
Change of Heating Value, pH and FT-IR Spectra of Charcoal at Different Carbonization Temperatures
Kwon, Sung-Min ; Jang, Jae-Hyuk ; Lee, Seung-Hwan ; Park, Sang-Bum ; Kim, Nam-Hun ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 440~446
DOI : 10.5658/WOOD.2013.41.5.440
To understand transition characteristics from wood to charcoal, Quercus variabilis wood was carbonized at 200, 250, 300, 340, 540 and
, respectively. Heating value, pH and surface property by FT-IR spectroscopy of the carbonized charcoal were investigated. Heating value and pH increased with increasing carbonization temperature from 4500 cal/g and 4.3 of the control wood to 8,000 cal/g and 9 of the charcoal carbonized at
, respectively. From FT-IR spectroscopy, the peaks from O-H, C-H and C-O stretching disappeared during carbonization at 540 and
. Aromatic skeletal vibration at near
was repidly increased until
. These results suggest that the chemical and physical characteristics of wood components in cell wall can be easily changed by increasing carbonization temperature and the carbonization seem to be incomplete at temperature below
Evaluation of the Efficiency of Solvent Systems to Remove Acetic Acid Derived from Pre-pulping Extraction
Park, Seong-Jik ; Moon, Joon-Kwan ; Um, Byung-Hwan ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 447~455
DOI : 10.5658/WOOD.2013.41.5.447
Hemicellulose extract obtained by pre-pulping extraction of woodchips, is very diluted acidic in nature. The major component responsible for this weak acidity is acetic acid, present in levels up to 5~10 g/L. Here, we report an exploratory study on the extract upgrading by reactive solvent extraction of acetic acid as well as ASPEN simulation. In this study, liquid-liquid equilibria for the ternary systems (water + acetic acid + ethyl acetate) were measured at the temperature of 298.15 K and 10 (pH = 2.02), 5 (pH = 2.17), and 1 (pH = 2.48) percent of acetic acid samples were used to carry out liquid-liquid extraction studies using ethyl acetate. In a one-stage batch experiment, 96.0% of acetic acid could be extracted for the solvent when the ratio of organic-to-aqueous phases is 4:1. For simulation results, they were used to estimate the interaction parameters between each of the three compounds of the systems studied for the NRTL and UNIQUAC models. The estimated interaction parameters were successfully used to predict the equilibrium compositions by the two models.
Effect of Alternating Vacuum and Release Process on Drying Characteristics of Log Cross Section during Radio Frequency Drying
Xie, Dan ; Lee, Nam-Ho ; Chang, Yoon-Seong ; Yeo, Hwanmyeong ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 456~465
DOI : 10.5658/WOOD.2013.41.5.456
Log cross sections of yellow poplar were dried in a radio frequency vacuum (RFV) dryer under alternating vacuum and release (AVR) process. The average moisture content (MC), temperature and vapor pressure at the volumetric center were monitored as functions of time. Three different log thicknesses (33, 60 and 75mm) were tested. The results show that the AVR process caused an increase in the drying rate when the moisture content was above fiber saturation point (FSP, about 30% MC) but that it had an inverse effect on the drying rate when the MC was below FSP. The effect of the AVR process on the drying rate decreased, and the severity of heart checks increased, with the increase in the thickness of the specimens.
Nondestructive Evaluation of Strength Performance for Heat-Treated Wood Using Impact Hammer & Transducer
Won, Kyung-Rok ; Chong, Song-Ho ; Hong, Nam-Euy ; Kang, Sang-Uk ; Byeon, Hee-Seop ;
Journal of the Korean Wood Science and Technology, volume 41, issue 5, 2013, Pages 466~473
DOI : 10.5658/WOOD.2013.41.5.466
Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for heat-treated wood under different conditions. The effect of heat treatment on the bending strength and NDE technique using the resonance frequency by impact hammer and force transducer mode for Korean paulownia, Pinus densiflora, Lidiodendron tulipifera and Betula costata were measured. The heat treatment temperature has been investigated at
, respectively. There were a close relationship of dynamic modulus of elasticity and static bending modulus of elasticity to MOR. In all conditions, It was found that there were a high correlation at 1% level between dynamic modulus of elasticity and MOR, and static modulus of elasticity and MOR. However, the result indicated that correlation coefficient is higher in dynamic modulus of elasticity to MOR than that in static modulus of elasticity to MOR. Therefore, the dynamic modulus of elasticity using resonance frequency by impact hammer mode is more useful as a nondestructive evaluation method for predicting the MOR of heat-treated wood under different temperature and species conditions.