• Journal of the Korean Wood Science and Technology
• /
• v.29 no.2
• /
• pp.69-75
• /
• 2001

This study was carried out to investigate the properties of woodceramics made from thinned logs of Cryptomeria japonica. In order to find the effect of steam injection time on the woodceramics fabricated with boards, boards were made with the non-steamed treatment and steamed treatment 1, 5, 10 min. at $250^{\circ}C$. The percentage of weight loss was proportional to the increased density of board The reducing rate of length and thickness, however, decreased with increasing density of board. The rate of weight loss, length and thickness reduction in non-steamed board were slightly higher than those of steamed board. When the resin impregnation rate increased, the bending strength and compressive strength of woodceramics had a tendency to increase. The bending strength and compressive strength of woodceramics in non-steamed board was higher than those of steamed board. But there was little difference between dimensional and strength properties of woodceramics and steam injection time of board.

• Conservation Science in Museum
• /
• v.10
• /
• pp.43-61
• /
• 2009

The Buyeo National Museum was requested conservation treatment for wooden objects excavated from three Baekje archeological sites: Neungsan-ri, Ssangbuk-ri, and Gungnamji Pond. Prior to conservation treatment, analysis was conducted to identify the species used. The results of the analysis revealed wood from diverse species of trees including Hard pine, Cryptomeria japonica D. Don, Zelkova serrata Makino, Quercus spp., Platycarya strobilaceae S. et Z., Castanea spp., Torreya nucifera S. et Z., Taxus cuspidata S. et Z., and Salix spp. A high percentage of the objects were made of Cryptomeria japonica D. Don., a species native to Japan, which indicates that exchange with Japan was active at that time. Among the wooden objects, we analyzed lacquer fragments from six pieces of lacquerware, and the characteristics of the lacquer fragments were peculiar to specific artifacts. Most of the fragments were thicker than 100 ㎛. Pure lacquer and mixed black pigment were used. Infrared spectroscopy of the lacquered wooden fragments revealed that they had a very similar absorption band as refined lacquer, confirming that they were painted with lacquer. For their conservation, we immersed the objects in a high molecular weight aqueous solution of PEG#3,350 (10% → 50%) to strengthen them before vacuum freeze-drying.

• Journal of Korean Society of Forest Science
• /
• v.113 no.1
• /
• pp.97-106
• /
• 2024

Evaluating carbon (C) and nitrogen (N) inputs from litterfall is important for soil nutrient management to enhance forest productivity and to understand the mechanisms of nutrient cycling in forest ecosystems. This study was conducted to compare C and N inputs from litterfall components of Cryptomeria japonica D. Don an d Chamaecyparis obtusa Endlicher planted in adjacent sites in the Jinju Research and Experimental Forests in Gyeongsangnam-do, South Korea. Litterfall into litter traps was collected at three-month intervals between December 2020 and December 2021, and the C and N concentrations of the litterfall components were measured. Litterfall amounts were not significantly different between the plantations, except for reproductive litterfall components. Litterfall accumulation peaked between December and March. The litterfall C concentration in the needle and seed litterfall was significantly higher for C. obtusa than for C. japonica. By contrast, the C concentrations in needle and flower litterfall differed seasonally. The mean N concentration of needle litterfall was significantly higher in C. japonica (0.96%) and C. obtusa collected between June and September (1.01%) than in the other seasons (C. japonica: 0.43%; C. obtusa: 0.53%). Carbon and N inputs in both plantations were highest in needle litterfall collected from December to March and lowest in needle litterfall collected from June to September. Annual C input by litterfall was similar between the plantations (C. japonica: 3,054 kg C ha^-1 yr^-1; C. obtusa: 3,129 kg C ha^-1 yr^-1), whereas total N input was higher for C. japonica (46.93 kg N ha^-1 yr^-1) than for C. obtusa (25.17 kg N ha^-1 yr^-1). The higher N input in the C. japonica plantation than in the C. obtusa plantation was associated with the input of reproductive components. These results could be applied to improve stand-scale models of C and N cycling by litterfall components in C. japonica an d C. obtusa plantations.

• Applied Biological Chemistry
• /
• v.44 no.4
• /
• pp.262-268
• /
• 2001

Two commercial wood vinegar liquors prepared from Cryptomeria japonica and Quercus sp., which are used as a mineral fertilizer in Korea, were extracted using dichloromethane as a solvent, respectively. The extracts were separated into acidic, phenolic, neutral and basic fraction by acid or alkali treatment, and the compositions of each fraction were analyzed by means of GC and GC-MS. A total of 103 compounds including 26 acids, 32 phenols and 45 neutral compounds were identified. The major components were acetic, propionic and n-butyric acid, representing of $41{\sim}58%$ of the acidic fraction, guaiacol, 4-methylguaiacol and phenol, repersenting of $53.2{\sim}63.9%$ of the phenolic fraction, and furfural, 3-methyl-2-cyclopenten-2-one, 2,3-dimethyl-2-cyclopenten-1-one and 5-methyl-2-furfural in the neutral fraction. In addition to these compounds, phenolic fraction in dichloromathane extract from wood vinegar liquor of C. japonica included large amounts of vanillin, acetovanillone and tentatively identified ethylvanillyl ether while that of Quercus sp. included some amounts of syringol and 4-methylsyringol.

• Journal of the Korean Wood Science and Technology
• /
• v.23 no.4
• /
• pp.1-9
• /
• 1995

This study was carried out to experiment the dimensional stabilization of woods of red pine (Pinus densiflora S. et Z.) and sugi(Cryptomeria japonica D. Don) by vacuum impregnation of polyehtylene glycols(PEG) with mo. wt. 200, 400, 600, 1000; polypropylene glycols (PPG) with mo. wt. 425,725 ; PEG-acryloylates, and PPG-acryloylates synthesized, and then by water soaking. The results obtained are as follows: 1. The density of sapwood and heartwood was different from each other in both species. 2. The PEG and PEG-macromers with lower molecular weight by impregnation has increased the density of wood specimens more higher, thereby caused their higher volume expansion, and those with higher molecular weight than 600 has tended to down their density increment. 3. Before and after water soaking, the density decrease of specimen impregnated was high in woods impregnated with simple PEG and PPG, while lower in specimens impregnated with PEG-macromers and PPG-macromers. 4. So PEG-macromer was expected to hold the original dimension of decayed wood for antiques, but it was necessary to develop another penetration method as well as aqueous solvent.

• Journal of Korean Society of Forest Science
• /
• v.113 no.1
• /
• pp.66-72
• /
• 2024

Determining the nutrient stoichiometry in plant organs is critical for understanding nutrient uptake and cycling in forest ecosystems. This study evaluated nutrient concentrations and stoichiometry in various plant organs (stem, bark, branches, and foliage) of species found in four warm-temperate forests in southern Korea. Cryptomeria japonica D. Don (CJ), Quercus serrata Thunb. (QS), evergreen broadleaved tree species (EB), and bamboo spp. (BB) were destructively sampled to measure nutrient (C, N, and P) concentrations in the plant organs. The mean C concentration in the stem was significantly higher in CJ than in QS, BB, or EB, whereas the C concentration in the foliage was the lowest in BB. The mean foliar N and P concentrations were higher in BB than in EB or CJ. The mean stem C:N and C:P ratios were highest in CJ but were lowest in the foliage of BB. Overall, stems of all species showed a strong positive correlation between C concentration and dry weight, but a negative correlation between N and dry weight. The N and P concentrations of foliage and bark were strongly correlated, whereas those of the stem and branches were poorly correlated. Positive correlations were detected between the C:N and C:P ratios in bark and foliage. These results indicate the existence of intraspecific differences in nutrient requirements in warm-temperate forest species and add to the understanding of nutrient uptake and storage patterns in the organs of species growing in warm-temperate forests.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2018.10a
• /
• pp.24-24
• /
• 2018

Degraded plantation forests are increasing because of unfavorable forestry conditions prevailing in Japan, including falling timber prices, increasing operational costs, and aging and declining forestry workforce. To remedy this situation, appropriate management strategy is required. This study introduces the challenges of Odai Town, Mie Prefecture that employed a new management strategy by evaluating site suitability for conifer forests and that proposes a new forest management regime of planting deciduous trees in unsuitable sites. The site suitability for conifer forests was evaluated from two aspects: the natural site conditions and the relationship among site conditions, growth, and damage by Anaglyptus subfasciatus Pic. in Cryptomeria japonica D. Don and Chamaecyparis obtusa Sieb. Et Zucc. forests. By analyzing the relationship among site conditions, growth, and insect damage based on field data obtained in plantation forests, growth evaluation and insect damage evaluation maps were developed. Based on the natural forest investigation, natural site condition maps for C. japonica and C. obtusa were established. Furthermore, by integrating these evaluation maps with the forest road maps showing the accessibility to the forest, the forest management regime for the whole plantation area of Odai Town was established. The forest management regime map indicates the sites suitable for forestry: suitable for long-rotation, short-rotation, and potential sites for short-rotation. The sites unsuitable for forestry were considered to be more suitable for broadleaved forests. Clear-cutting was conducted in a small area and different seral stage saplings (approximately 20 deciduous tree species) suitable to the site conditions were planted in an area of $80-120m^2$ protected by deer-fences. This might establish a forest composed of many species with a multilayer vertical forest structure in a short period. The planted saplings were distributed neither randomly nor uniformly to reflect the natural distribution of trees in the forest. A challenge to develop new products using the deciduous trees has started, such as wood chips for preparing smoked food, essential oil, and deodorizer. As these challenges have just begun, their effects on enhancing sustainable resource management are still being monitored. Even with the challenges, this regime can be of high value as a management strategy to remedy the situation of expansion of degraded forests in Japan.

• Journal of agriculture & life science
• /
• v.50 no.1
• /
• pp.105-115
• /
• 2016

This study was carried out to establish the optimum forest management plan for the Cryptomeria japonica plantations in southern inland and Jeju island in Korea. Sixty seven circular sample plots of 0.04ha were established and we surveyed vegetation structure and growth characteristics from three layers(upper, middle, and lower). As a result of cluster analysis obtained by importance values of each tree species, the community type of C. japonica stands were classified into C. japonica group(C1) and C. japonica-C obtusa group. C. obtusa community were also sbudivided into P. thunbergii-Q. serrata group(C2) and Q. serrata-C obtusa group(C3). In tree layers importance value(IV) of C. japonica were 97.2% in C1, 80.7% in C2, and 47.6% in C3 and in sub-tree layers IV were 8.9% in C1, 15.2% in C2, and 5.7% in C3. Especially in C3 there are bamboo species (Smilacina japonica var. lutecarpa and Pseudosasa japonica) it is necessary for us to control them. In shrub layers C. japonica were found in C1(9.2%) and C2(7.0%), but except for C3. In tree layer species diversity indices of each community ranged from the lowest 0.059 in C1 to the highest 0.548 in C3. Dominance ranged from 0.958 in C1 to 0.393 in C3 which may caused by interspecific competition. Current annual increment of diameter growth ranged from 7.01mm/yr to 8.04mm/yr. As a result of our study we recommend the application of proper thinning and pruning for C1 and C2.

• Journal of the Korean Wood Science and Technology
• /
• v.29 no.1
• /
• pp.22-30
• /
• 2001

Composites with various layer constructions involving the ratio of S/P were produced from wood strands(S) and particles(P) (Cryptomeria japonica D.Don) to measure various Young's moduli and anisotropy by ultrasonics. As a result, static Young's moduli of composites were almost same as dynamic Young's moduli obtained from natural frequency. However, these were smaller than those evaluated from ultrasonic wave propagation velocity. The differences between propagation velocity of the parallel(${\parallel}$) and perpendicular(${\bot}$) in-plane direction resulted in a tendency of anisotropy. The tendency of anisotropy was larger in three-layer constructions than in seven-layer constructions. The differences of strand surface layers showed larger values than those of particle surface layers. Also, composites with higher weight ratio of strand had a tendency to propagate rapidly in each direction. In contrast to these results, the propagation velocity in the thickness direction had a tendency to propagate rapidly in composites with particle surface layers and the lower weight ratio of strand.

• Journal of Korean Society of Forest Science
• /
• v.71 no.1
• /
• pp.14-21
• /
• 1985

This study was carried out in order to prevent the devaluation of wood itself and wood products causing by anisotropy, hygroscopicity, shrinkage and swelling - properties that wood itself only have, in order to improve utility of wood, by emphasizing the natural beautiful figures of wood, to develop the dimensional stabilization techniques of wood with PEG that it is a cheap, non-toxic and the impregnation treatment is not difficult, on the effects of PEG molecular weights (200, 400, 600, 1000, 1500, 2000, 4000, 6000) and species (Pinus densiflora S. et Z., Larix leptolepis Gordon., Cryptomeria japonica D. Don., Cornus controversa Hemsl., Quercus variabilis Blume., Prunus sargentii Rehder.). The results were as follows; 1) PEG loading showed the maximum value (137.22%, Pinus densiflora, in PEG 400), the others showed that relatively slow decrease. The lower specific gravity, the more polymer loading. 2) Bulking coefficient didn't particularly show the correlation with specific gravity, for the most part, indicated the maximum values in PEG 600, except that the bulking coefficient of Quercus variabilis distributed between the range of 12-18% in PEG 400-2000. In general, the bulking coefficient of hardwood was higher than that of softwood. 3) Although there was more or less an exception according to species, volumetric swelling reduction was the greatest in PEG 400. That is, its value of Cryptomeria japonica was the greatest value with 95.0%, the others indicated more than 80% except for Prunus sargentii, while volumetric swelling reduction was decreased less than 70% as the molecular weight increase more than 1000. 4) The relative effectiveness of hardwood with high specific gravity was outstandingly higher than softwood. In general, the relative effectiveness of low molecular weight PEG was superior to those of high molecular weight PEG except that Quercus variabilis showed more than 1.6 to the total molecular weight range, while it was no significant difference as the molecular weight increase more than 4000. 5) According to the analysis of the results mentioned above, the dimensional stabilization of hardwood was more effective than softwood. Although volumetric swelling reduction was the greatest at a molecular weight of 400. In the view of polymer loading, bulking coefficiency reduction of swelling and relative effectiveness, it is desirable to use the mixture of PEG of molecular weight in the range of 200-1500. To practical use, it is recommended to study about the effects on the mixed ratio on the bulking coefficient, reduction of swelling and relative effectiveness.