WOOD RESEARCH Volume 68, Number 3, 2023
Chun-Won Kang, Kazuharu Hashitsume, Eun-Suk Jang, and Haradhan Kolya

Relationship between Wood Anatomical Features and Surface Roughness Characteristics

This study aimed to investigate the relationship between surface roughness and anatomical features of wood in 15 different species of boards. Surface roughness was measured parallel and perpendicular to the wood grain using a surface profilometer, and anatomical features such as pore size and distribution were analyzed using microscopic techniques. The results showed that surface roughness perpendicular to the grain direction was consistently higher than that parallel to the grain direction for all wood samples. This difference in roughness was correlated with pore size and density. It shows that the larger pores and lower density lead to higher roughness perpendicular to the grain. The study also found that traditional hand planning methods (push and pull) produced a smooth surface finish, with no statistical differences in roughness.

WOOD RESEARCH Volume 67, Number 5, 2022
Eun-Suk Jang and Chun-Won Kang

Short notes: Can the physical properties of wood samples be predicted from photographs displayed on a monitor?

This study focused on evaluating the physical properties of wood from photographs displayed on a monitor. Sample photos of 475 hardwoods and their physical information were collected from a wood database. R, G, and B values were extracted from the wood photos using color picker software. Statistical techniques such as Pearson’s correlation coefficient and multiple regression analysis were applied to investigate relationships between wood color and physical properties. From results of Pearson’s correlation coefficient, R, G, and B values were most affected by specific gravity. In a multiple regression analysis, tree size, specific gravity, and modulus of rupture (MOR) were significant in the positive (+) direction by color (R, G, and B). On the other hand, modulus of elasticity (MOE) was significant in the negative (-) direction at the 1% level by color. The specific gravity of wood had the most significant effect on R, G, and B values in multiple regression analysis. In conclusion, the color and specific gravity of wood were related closely. Additionally, it is possible to predict the physical properties of wood from the R, G, and B values of a wood sample photograph displayed on a monitor. These results could provide useful information for wood researchers as well as wood exporters and importers.

WOOD RESEARCH Volume 67, Number 4, 2022
Eun-Suk Jang and Chun-Won Kang

Investigation on the Malaysian Duabanga moluccana cross sections as sound absorbing functional materials

This study focused on Duabanga moluccana, which is a fast-growing tropical tree native to Southeast Asia. Duabanga moluccana cross sectional specimens were analyzed to gas permeability, pore size, and open-pore porosity and also measured its sound absorption coefficients with an impedance tube. Duabanga moluccana showed a larger pore size and greater open-pore porosity than other hardwood species, and its sound absorbing performance was superior to that of the gypsum board currently used as a commercial ceiling material. Although this was a laboratory-scale investigation, we demonstrate that Duabanga moluccana cross sections have potential as a natural sound absorbing functional building material.

WOOD RESEARCH Volume 67, Number 3, 2022
Eun-Suk Jang and Chun-Won Kang

Why the sound-absorbing performance of heartwood and sapwood differs in yellow poplar (Liriodendron tulipifera) cross-sections?

In this study, we investigated why the sound-absorbing performance is different with between heartwood and sapwood of yellow poplar, which are known for their sound-absorbing properties. We performed image observation as well as gas permeability, pore size, and porosity analysis, and measured the sound absorption coefficient of all samples using an impedance tube. We determined that the pores were significantly larger, and the gas permeability and through-pore porosity much higher, in the sapwood than the heartwood. The average sound absorption coefficient of the sapwood at 2000-6400 Hz (0.61 ± 0.04) was 2.7x that of the heartwood (0.23 ± 0.03). The average NRC of the sapwood (0.23 ± 0.01) was 1.9x that of the heartwood (0.12 ± 0.01). This study ultimately determined that the sapwood, as a consequence of its larger pore size and superior through-pore porosity, which thereby improved its gas permeability, outperformed the heartwood in terms of sound-absorption. We also determined that pore size and through-pore porosity were the primary parameters that determined the sound-absorbing performance of yellow poplar cross-sections.

WOOD RESEARCH Volume 67, Number 2, 2022
Eun-Suk Jang and Chun-Won Kang

The relationship between bulk density and thermal conductivity in various korean woods

The article deals with the effects of bulk density on thermal conductivity in specimens of 15 Korean woods (Zelkova serrata, Pinus densiflora, Cornus controversa, Betula schmidtii, Betula platyphylla var. japonica, Ginkgo biloba L., Cedrela sinensis A. Juss., Fraxinus mandshurica, Ulmus davidiana var. japonica, Prunus sargentii Rehder, Paulownia tomentosa (Thunb.) Steud., Larix kaempferi (Lamb.) Carrière, Robinia pseudoacacia, Kalopanax septemlobus and Tilia amurensis). The results of this study were compared with previous studies performed on wood specimens from China, India, and Turkey. Consistent with these previous studies, bulk density and thermal conductivity were positively correlated in Korean woods, and a simple regression model with a very high correlation of R2 (94%) was obtained. Interestingly, we observed some variation between our simple regression models and those generated by previous researchers who had examined non-Korean woods.