• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.2
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• pp.1-10
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• 2011

Six pine trees (Pinus densiflora S. et Z.) at the Euilimji Lake Park in Jecheon were collected to investigate tree ages, growth decline pattern and the years of death. Tree-ring measurement was carried out using the Lintab with a resolution of 0.01mm. Tree age were 80-176 years. Cross-dating between the tree-ring series of each tree and the local chronology from Worak Mountain resulted that four and two trees died in 1998 and 1999, respectively. Three dead trees had only formed earlywood in the outermost tree ring and the others had incomplete latewood. Therefore, it was proven that the former trees died between spring and early summer, whereas the later ones died during late summer and/or autumn. The simultaneous deaths of trees suggest the insect damage and/or drought may be the crucial reason of the death, but frequent reaction woods, which were formed by leaning stem, and scars formed by physical damage may also contribute to the death.

• Interaction and multiscale mechanics
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• v.5 no.3
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• pp.229-265
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• 2012

Hygroexpansion of wood is a known and undesired characteristic in civil engineering. When wood is exposed to changing environmental humidity, it adsorbs or desorbs moisture and warps. The resulting distortions or - at restrained conditions - cracks are a major concern in timber engineering. We herein present a multiscale model for prediction of the macroscopic hygroexpansion behavior of individual pieces of softwood from their microstructure, demonstrated for spruce. By applying poromicromechanics, we establish a link between the swelling pressure, driving the hygroexpansion of wood at the nanoscale, and the resulting macroscopic dimensional changes. The model comprises six homogenization steps, which are performed by means of continuum micromechanics, the unit cell method and laminate theory, all formulated in a poromechanical framework. Model predictions for elastic properties of wood as functions of the moisture content closely approach corresponding experimental data. As for the hygroexpansion behavior, the swelling pressure has to be back-calculated from macroscopic hygroexpansion data. The good reproduction of the anisotropy of wood hygroexpansion, based on only a single scalar calibration parameter, underlines the suitability of the model. The multiscale model constitutes a valuable tool for studying the effect of microstructural features on the macroscopic behavior and for assessing the hygroexpansion behavior at smaller length scales, which are inaccessible to experiments. The model predictions deliver input parameters for the analysis of timber at the structural scale, therewith enabling to optimize the use of timber and to prevent moisture-induced damage or failure.

• Journal of Korean Society of Forest Science
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• v.46 no.1
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• pp.44-52
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• 1980

The purpose of this study was carried out to examine the systematic trends in fibril angle which existed within the trunk of Pinus koraiensis Sieb. et Zucc. In 1937 I. W. Bailey reported that crystalline aggregates of iodine may be induced to form within the elongated interstices of the cellulose matrix of the secondary wall, and that these elongated crystals are oriented parallel to the long axis of the fibrils of cellulose. The authors tried a simple method (Yaichi kobayashi method) of demonstrating the fibrillar orientation in lignified walls in which Schulze's reagent was used. The results were summarized as follows. 1. Fibril angles were greater for earlywood (avg. $23.38^{\circ}$) than for latewood (avg. $17.85^{\circ}$). 2. The average fibril angles of consecutive rings decreased consistently and markedly from pith to bark. 3. Differences of the fibril angle between in springwood and in summerwood were greater in corewood than in middle or outerwood.

• Journal of Korea Foresty Energy
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• v.20 no.1
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• pp.62-72
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• 2001

To elucidate the behaviors of alkali swelllng of woods. the dimensional change in cross section of cell elements of four major Korean woods during alkali swelling were examined by an optical microscory, an imaging analysis method and an X-ray diffrartion During alkali swelling, tracheid diameter of Larix kaempferi wood showed greater swelling property than that of Pinus koraiensis wood, and the cell wall swelled highly over 10% sodium hydroxide solution treatment. The radial diameter of vessel elements in earlywood shrunk, but it swelled slightly in tangential direction. When treated with 5% NaOH, the wall thickness of wood fiber increased about three times over the original one. The thickness of cell wall in all elements and the diameter of wood fiber and tracheid showed almost isotropic shrinkage. The diameter of cell elements during the mercerization process decreased, but cell wall thickness Increased. Crystal transformation of cellulose in wood was not occurred by alkali treatments. but relative crystallinity and crystallite width of the woods increased slightly. Consequently, it was demonstrated that the swelling properties of woods were dependant on wood species, cell elements and alkali concentration.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.157-165
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• 2016

This study investigated several anatomical characteristics of Paulownia tomentosa roots. The root wood was separated into three parts from stem base (top, middle, and base) at different positions below ground. Qualitative anatomical data suggested that the growth rings in earlywood and latewood were structurally different. Furthermore, the root wood vessels were found having 2 to 3 radial multiples and they were appeared in the form of clusters. In addition, some sheath cells and septate axial parenchyma were observed. Regarding the quantitative anatomical characteristics, vessel and ray numbers per $mm^2$, as well as ray width and height differed significantly among the top, middle, and base rood wood parts. However, there were no significant differences in vessel diameters, cell wall thickness, and width and length of wood fibers among those parts. The crystallinity of the root top part was slightly higher than that of the middle and base parts. Furthermore, the vessel numbers, ray numbers, and ray width and height in the near pith (NP) area were higher compared to those in the near bark (NB) area. However, the fiber width and fiber length at NP were lower than those at NB. Overall, this study demonstrated some significant differences in the anatomical characteristics of the top, middle, and base parts of root wood from Paulownia tomentosa.

• Journal of the Korean Wood Science and Technology
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• v.44 no.3
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• pp.295-301
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• 2016

In this study, relationship between seed origin and growth rate of Alnus glutinosa from different seed collection (Yugoslovia, ltaly, United Kingdom, Bulgaria) was investigated with focused on anatomical properties as wood fiber length, vessel element length and diameter. Alnus glutinosa showed diffuse-porous wood with scalariform perforation in alternate pitting. Ray height was 9~11 in tangential section and ray number were 16~26 in cross section. There were no differences on latewood focused on wood fiber length, length and diameter of vessel element, but difference on earlywood. Other than Yugoslavian seed, there was better growth rate with shorter wood fiber and vessel element length on latewood. However, seed from Yugoslovain showed better growth rate with longer wood fiber and vessel element length than other 3 seed orgins.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.117-126
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• 1997

In fast grown softwood, there are very large changes in material properties going outward from the pith to bark such as anatomical, physical and mechanical characteristics. Some of variations in anatomical properties with annual ring were then examined from Pinus koraiensis, Larix leptolepis, and Chamaecyparis obtusa, which are major softwoods of plantation in Korea. The large variations of annual ring width during young age of tree tended to stabilize after 25year through the transitional period in 17~23year. The ring density was 1.5~2.4 in 1~10year period, and 3.5~6.3 in 30~35year period, in which juvenile and mature wood were certainly assumed to be formed, respectively. Variations of tracheid length showed functional relationships with annual rings as logarithm. Demarcation between juvenile wood and mature wood could be 16~19year, which was determined from increase rate of tracheid length of 0.2%. Cell wall thickness increased with increase of annual ring even though large variations were observed as well. Variations of cell wall thickness within species were pronounced in latewood than earlywood. The increase of cell wall thickness from juvenile wood to mature wood was predominant in Larix leptolepis as 2.0times, and least in Chamaecyparis obtusa as 1.1 times. Cell diameters showed trends of increase during young age of 1~15year, and consistent afterward. The variations of cell diameter between radial and tangential direction were greater in latewood, and most pronounced in Chamaecyparis obtusa.

• Journal of Korean Society of Forest Science
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• v.80 no.3
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• pp.296-302
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• 1991

Compression wood and opposite wood formed in a branch of Taxodium distichum Rich. is described and compared in qualitative and quantitative anatomical aspects. The qualitative features of compression wood appeared to differ from those of opposite wood in very gradual tracheid transition from earlywood to latewood, roundish tracheid shape on cross surface, tracheid tip distortion on radial surface, and existence of intercellular spaces and helical cavities. In quantitative features, compression wood tracheids showed shorter lengths than opposite wood. The ray density and the number of uniseriate rays were greater in compression wood than in opposite wood but the height of uniseriate rays in compression wood was smaller than in opposite wood.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.1-17
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• 2000

Crystals in the woods and barks of Populus maximowiczii and Populus nigra ${\times}$ maximowiczii were examined by light microscopy, scanning electron microscopy and soft X-ray. Populus examined had the wetwood and the heartwood of Populus showed higher moisture content than in adjacent sapwood. The crystals can be detected clearly by the soft X-ray due to their higher densities than the wood. Crystals in xylem wood of Populus were found mainly at heartwood. However, they were concentrated in specific areas such as in color-stained area or along the specific annual rings. Crystals showed the highest occurrence around the pith. Within a growth ring the amount of crystals in earlywood was more abundant than in latewood. Crystals were observed mainly at vessels and fibers although they occurred at all kinds of cells in heartwood. Crystals in the bark were scattered evenly both in inner bark and in outer bark. Populus nigra${\times}$maximowiczii showed higher frequency of leaf knots than Populus maximowiczii.

• Journal of the Korean Wood Science and Technology
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• v.15 no.2
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• pp.105-112
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• 1987

Some anatomical characterisitcs of Japanese red pine (Pinus densiflora S. et Z.) collected from pollution-exposed areas in Korea were investigated. These sites were reportedly the most severe air polluted areas in Korean peninsular. A decline in overall growth rate was apparent since the late 10-year period of growth. P. densiflora in Onsan and in Yeochon recorded in the radial growth reduction of approximately 70 and 60% respectively. The formation of earlywood in the period of air pollution was restricted, whereas the percentage of latewood increased. The maximum wood density was lower in xylem rings formed during a period of air-pollution than in rings found without pollution. Most of pine trees damaged by air pollution showed the classical type of length-on-age curve for tracheids. However, reduction in cell wall-thickness and diameter was revealed in the wood exposed to air pollutants. Nor anomalies in microstructures nor microorganisms in wood structures were found in the damaged trees.