• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.742-746
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• 2001

This study was carried out to develop volume equations for Japanese Res Cedar(Cryptomeria japonica D. Don) trees which were widely planted from 1920s throughout the southern regions in south Korea. The 31 trees for stem analysis were selected in 6 different sites in the southern and 29 trees data were used for developing volume equation. The best equation in estimating Japanese Red Cedar trees's volume was suggested as $V=-0.002908+0.000125D^{1.907114}H^{0.645131}$. The simultaneous F-test for this equation revealed that the estimated individual tree volume was not significantly different (p=0.1936) from the observed tree volume for model evaluation. Therefore, this individual tree volume prediction equation could provide basic information for the construction of yield table and forest management.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.169-178
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• 2020

This study aimed to compare the organic carbon stocks of Cryptomeria japonica and Chamaecyparis obtusa stands established under a similar-site environmental condition in South Korea. C. japonica and C. obtusa stands adjacent to each other from 13 representative regions were chosen to evaluate the carbon stocks of tree biomass, forest floor, and mineral soils. Mean stand ages were 45 years for C. japonica and 43 years for C. obtusa, respectively. Tree density was significantly lower in C. japonica (989 tree ha^-1) than in C. obtusa (1,223 tree ha^-1) stands, whereas diameter at breast height and dominant tree height values were significantly higher in C. japonica (27.4 cm and 20.4 m, respectively), compared with C. obtusa (23.9 cm and 17.9 m, respectively) stands. The total carbon stocks of tree biomass were linearly related with stand basal area (C. japonica: r² = 0.82; C. obtusa: r²= 0.92; P< 0.05), whereas stand density and site index were not correlated with the carbon stocks of tree biomass (P > 0.05). The carbon stocks of aboveground tree biomass were significantly higher in C. obtusa (117.7 Mg C ha^-1), compared with C. japonica (95.5 Mg C ha^-1) stands, whereas carbon concentration and stocks of the forest floor and mineral soil layers were insignificantly different between the C. japonica and C. obtusa stands. The results indicated that trees in C. obtusa stands sequestrated more carbon dioxide, compared with C. japonica stands, whereas carbon stocks in the forest floor and mineral soil layers were unaffected by stand development processes of the different tree species.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.33-40
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• 2008

Normally, cedar heartwood has a red color. However, it frequently changes black color (blackening phenomenon). It is reported that blackening phenomenon of cedar has been caused by oxidation of phenolics and norlignan extractives under weak alkaline conditions. In this study, heat treatment and UV irradiation were carried out to reduce the difference of color value between blackened wood and bright sap wood. Effects of temperature, moisture content, treatment time and light on decrease of color difference between blackened heartwood and sapwood were evaluated in each treatment. A decrement of different color value between blackened heartwood and bright sapwood by hot-water treatment was bigger than others. An effect of the vacuum drying was similar to that of the kiln drying. UV irradiation decreases the color difference between dried blackened heartwood and bright sapwood. It is suggested that UV irradiation could be used as final treatment to reduce the color difference on wood during drying process. Determination of optimum conditions and development of hybrid process for control of discoloration will be needed in a further study.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.495-510
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• 2017

This study was to investigate the antioxidant activities of Cryptomeria japonica leaves extracts such as essential oil, methanol extract and hot water extract and to evaluate its potential as a natural antioxidant. Antioxidant activities of extracts were evaluated by DPPH radical scavenging activity, FRAP activity, zanthin oxidase inhibitory activity, and iron ion chelate activity, comparing with the positive controls. According to the results, methanol and hot water extracts showed higher antioxidant activities than essential oil. This fact suggested that terpenoids have lower antioxidant effect than phenolic compounds which were found in methanol and hot water extracts. Especially, acetone and water soluble fractions of methanol extract and ethanol fraction of hot water extract contained a lot of phenolic compounds and hydroxyl group, indicating that many hydroxyl groups and glycosidic bonds showed higher antioxidant effect than the other fractions. These results can suggest that the phenolic compounds which contained hydroxyl group or glycosidic bonds have a certain role for effective antioxidant activities.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.515-522
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• 2023

The aim of this study was to quantitatively evaluate a new stem volume table for estimating the growth, carbon storage, and greenhouse gas (GHG) absorption in Cryptomeria japonica and Chamaecyparis obtusa stands and to provide suggestions for improving the domestic GHG inventory. Carbon storage and GHG absorption were estimated using growing stock data obtained from invariable sub-sample plots between the 6^th and 7^th national forest inventories. We assessed changes in growing stock using the parameters employed by Kozak (1988) and Versions 1 and 2 of the stem volume table. Version 2 has new stem tables for 16 species, including Cryptomeria japonica, which were unavailable in Version 1. Version 2 also includes new data for trees with diameters at breast height equal to or greater than 30 cm. We found greater growing stock values using Version 2 than Version 1 for both stands, and the differences were statistically significant (p<0.001). Applying the new stem volume table increased GHG absorption by 22% for the Cryptomeria japonica stand and 13% for the Chamaecyparis obtusa stand. The growing stock estimation method used in this study should therefore be applied to re-estimate GHG absorptions in the forestry sector to produce accurate statistics for the IPCC guidelines.

• Landscaping Tree
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• s.98
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• pp.10-18
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• 2007

• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.184-191
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• 2009

In the southern part of the Korean Peninsula including Jeju-island, the production amount of domestic cedar has increased gradually. However, their low qualities, expected to be caused by the low density and frequent knots, have restricted their practical utilization as the high value-added products. In this study, it is aimed to look for the new uses of domestic cedar and to examine the applicability for lamination lumbers of structural glued laminated timber (glulam). Above all, machine stress ratings for individual sawn lumbers confirmed that modulus of elasticity (MOE) of cedar lumber was lower than that of other common softwood species in Korea. On the other hand, cedar lumbers have enough stiffness to manufacture the structural glulam in accordance with Korean Industrial Standard (KS). The bonding strength and durability also met the KS limitation. Nevertheless, from the result of bending tests for cedar glulam, it was shown that the modulus of elasticity (MOE) did not meet the KS limitation. Therefore, it was concluded that additional researches were needed for reinforcing the stiffness of cedar glulam.

• Fire Science and Engineering
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• v.30 no.5
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• pp.60-66
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• 2016

This study investigated the structure and combustion characteristics of four species, Timber Douglas-fir being used construction materials (finishes), Lauan, Cryptomeria japonica, Pinus densiflora trees in the area. In lookong into the ignition characteristics was a time range of ignition (TTI) appeared in the 21 s~32 s, especially Pinus densiflora TTI is ignited in a relatively rapid 601 s to 21 s than the other materials were destroyed in the 631 s. The maximum heat release rate and average heat release rate is Pinus densiflora > Lauan > Cryptomeria japonica > Douglas-fir showed a net. Barrel emissions are Lauan > Douglas-fir > Pinus densiflora > Cryptomeria japonica was in order. The total emissions was postponed Pinus densiflora $424.80m^2/m^2$, Lauan $185.93m^2/m^2$. Douglas-fir carbon emissions of 1460, showing 0.185 kg/kg CO maximum value from s $CO_2$ values show the maximum value to 15,986 kg/kg in 750 s stopped in the 3,090 s. Next, the study suggested methods to utilize as the basic data for evaluating the safety of the fire as a building material.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.567-578
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• 2022

Various social and environmental problems have recently emerged due to global climate change. In South Korea, coniferous forests in the highlands are decreasing due to climate change whereas the distribution of subtropical species is gradually increasing. This study aims to respond to changes in the distribution of forest species in South Korea due to climate change. This study predicts changes in future suitable areas for Pinus koraiensis, Cryptomeria japonica, and Chamaecyparis obtusa cultivated as timber species based on climate, topography, and environment. Appearance coordinates were collected only for natural forests in consideration of climate suitability in the National Forest Inventory. Future climate data used the SSP scenario by KMA. Species distribution models were ensembled to predict future suitable habitat areas for the base year(2000-2019), near future(2041-2060), and distant future(2081-2100). In the baseline period, the highly suitable habitat for Pinus koraiensis accounted for approximately 13.87% of the country. However, in the distant future(2081-2100), it decreased to approximately 0.11% under SSP5-8.5. For Cryptomeria japonica, the habitat for the base year was approximately 7.08%. It increased to approximately 18.21% under SSP5-8.5 in the distant future. In the case of Chamaecyparis obtusa, the habitat for the base year was approximately 19.32%. It increased to approximately 90.93% under SSP5-8.5 in the distant future. Pinus koraiensis, which had been planted nationwide, gradually moved north due to climate change with suitable habitats in South Korea decreased significantly. After the near future, Pinus koraiensis was not suitable for the afforestation as timber species in South Korea. Chamaecyparis obtusa can be replaced in most areas. In the case of Cryptomeria japonica, it was assessed that it could replace part of the south and central region.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.19 no.3 s.31
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• pp.68-74
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• 2006

목적 : 삼나무(Cryptomeria japonica)로부터 얻은 정유의 구성과 구강박테리아에 대한 항균작용을 연구하였다. 방법 : 정유의 화학적조성은 GC 와 GC-MS에 의하여 분석하였고, 정유와 그 주성분에 대한 구강박테리아 15균주의 항균효과를 시험하였다. 결과 : 정유의 95.82%에 해당하는 68복합체를 증명할 수 있었다. 정유의 주요성분은 ${\alpha}-pinene$ (6.07%), sabinene (8.86%), limonene (3.43%), ${\gamma}-cadinol$ (4.28%), ${\beta}-eudesmol$ (3.90%), and 10(15)-cadien-4-ol (7.16%)이었다. 삼나무의 주요성분은 거의 모든 박테리아에 대하여 MICs, 0.025 to 0.05 mg/ml; MBCs, 0.025 to 0.1 mg/ml에서 유의성있는 억제효과를 나타내었고, 주요성분 또한 다양한 성장억제를 나타내었다. 결론 : 삼나무의 정유는 다종의 화학복합체로 이루어져 있으며, 이는 다종의 구강박테리아에 대해 항균작용을 갖고 있다.