• Journal of the Korean Wood Science and Technology
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• v.47 no.3
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• pp.371-380
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• 2019

Termites are pests that cause serious economic and cultural damage by digesting wood cellulose. Termites are arthropods and have an epidermis surrounded by a chitin layer. To maintain a healthy epidermis, termites have chitinase (${\beta}$-1,4-poly-N-acetyl glucosamidinase, EC 3.2.1.14), an enzyme that hydrolyzes the ${\beta}$-1,4 bond of chitin. In this study, the amino acid sequence of the gene, which is presumed to be termite chitinolytic enzyme (NCBI accession no. KC477099), was obtained from a transcriptomic analysis of Reticulitermes speratus KMT001 in Bukhan Mountain, Korea. An NCBI protein BLAST search confirmed that the protein is a glycoside hydrolase family 18 (GH18). The highest homology value found was 47%, with a chitinase from Araneus ventricosus. Phylogenetic analysis indicated that the KC477099 protein has the same origins as those of arthropods but has a very low similarity with other arthropod chitinases, resulting in separation at an early stage of evolution. The KC477099 protein contains two conserved motifs, which encode the general enzymatic characteristics of the GH18 group. The amino acid sequences $Asp^{156}-Trp^{157}-Glu^{158}$, which play an important role in the enzymatic activity of the GH18 group, were also present. This study suggests that the termite KC477099 protein is a new type of chitinase, which is evolutionarily distant from other insect chitinases.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.415-422
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• 2018

Terpenoids have a wide range of biological functions and have extensive applications in the pharmaceutical, cosmetic, and flavoring industry. The white-rot fungus, Polyporus brumalis, is able to synthesize terpenoids via terpene synthase, which catalyzes an important step that forms a large variety of sesquiterpene products from farnesyl pyrophosphate (FPP). To improve the production of sesquiterpenes, the terpene synthase gene was isolated from Polyporus brumalis and was heterologously transformed into a Pichia pastoris strain. The open reading frame of the isolated gene (approximately 1.2 kb) was inserted into Pichia pastoris to obtain a recombinant enzyme. Five transformants were obtained and the expression of terpene synthase was analyzed at the transcript level by reverse transcription PCR (polymerase chain reaction) and at the protein level by SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Expression of the terpene synthase gene product was elevated in the transformants and as expected the molecular weight of the protein was approximately 45 kDa. These recombinant enzymes have potential practical applications and future studies should focus on their functional characterization.

• Journal of Forest and Environmental Science
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• v.36 no.1
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• pp.62-66
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• 2020

Ethanol fermentation of the enzymatic hydrolysates from the products pretreated using 1-ethyl-3-methyl-imidazolium acetate ([EMIM]Ac) and its co-solvents with dimethylformamide (DMF) was conducted using Saccharomyces cerevisiae (D452-2). The optical density change due to the yeast cell growth, the consumption amount of monosugars (glucose, xylose), the concentration of acetate, and ethanol production yield were investigated. The co-solvent system lowered inhibition of the growth of the cells. The highest concentration of glucose (7.8 g/L) and xylose (3.6 g/L) was obtained from the enzymatic hydrolysates of the pretreated product by pure [EMIM]Ac. The initial concentration of both monosugars in the enzymatic hydrolysates was decreased with increasing fermentation time. Ethanol of Approximately 3 g/L was produced from the enzymatic hydrolysates by pure [EMIM]Ac and co-solvent with less than 50% DMF.

• Forest Science and Technology
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• v.13 no.4
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• pp.158-163
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• 2017

We examined the activities of lignin-degrading enzymes of the mycelium of cauliflower mushroom (Sparassis latifolia). Three different strains of S. latifolia collected from several sites in Korea and one crossbred strain were cultured on potato dextrose broth (PDB) and Kirk's medium in order to study the activities of their ligninolytic enzymes. Mycelial growth reached maximum levels between 14 and 21 days after inoculation and pH increased by 0.12 units over 35 days. Laccase activity began increasing after 14 days on both types of media. Manganese peroxidase (MnP) activity followed a trend similar to that of laccase on Kirk's medium, but not on PDB. The activity of lignin peroxidase (LiP) differed from that of other enzymes; its activity decreased by half after 14 days on PDB but remained constant on Kirk's medium over 35 days. The total protein concentration increased considerably after 14 days and peaked at 21 days on PDB. A similar maximum was attained on Kirk's medium. In contrast, the residual glucose increased rapidly at 14 days on Kirk's medium, while increasing gradually up to 28 days on PDB. This study indicates that S. latifolia is more similar to white rot fungi than to other brown rot fungi.

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.762-769
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• 2010

The composition of minerals and amino acids in Allium victorialis var. platyphyllum tissues collected from different habitats in Ulleung Island and Mt. Hambeak of the Korean Peninsula is investigated. The mineral composition of A. victorialis stem was high compared to that of bulb in all population samples. The most abundant mineral found in all the samples was potassium (K). The mineral composition was variable in garlic population of Ulleung Island in a habitat dependent manner. The A. victorialis stems and bulbs showed significant differences in their amino acid compositions according to varying habitats of Ulleung Island and Mt. Hambeak. Among the amino acids the most abundant amino acid in A. victorialis bulb tissue was arginine, followed by leucine and valine. The amino acids leucine, valine, and phenylalanine were abundant in stem tissues. The total amino acids of the A. victorialis stem tissue from Teawha pass peak sample (837 mg/100 g dry wt) were higher than the mean of other population samples (355-824 mg/100 g dry wt). However, content of amino acids in the bulb was high in A. victorialis from Nari basin (1,919 mg/100 g dry wt).

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.172-183
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• 2016

Densification of the inner part of oil palm trunk (OPT) by the close system compression (CSC) method was performed in this study. The effects of the compression temperature and time on the anatomical, physical and mechanical properties of OPT were evaluated. The inner part of OPT with an initial average density of $0.3g/cm^3$ was used as samples. Oven-dried samples were immersed in water and vacuumed until fully saturated and then compressed by CSC at 120, 140, 160 or $180^{\circ}C$ for 10, 20, 30 or 40 min. The anatomical characteristics of transverse and radial sections before and after compression were compared by optical microscopy. The physical and mechanical properties, including the density, recovery of set (RS), modulus of elasticity (MOE), modulus of rupture (MOR), and compression parallel to grain were examined. It was observed that the anatomical characteristic of the inner part of OPT (i.e., vascular bundles, vessels, and parenchyma tissue) became flattened, fractured, and collapsed after compression by CSC. The RS decreased with increasing compression temperature and time. The lower RS indicated high dimensional stability. The physical and mechanical properties (i.e., density, MOR, MOE, and compressive strength) of the inner part of OPT increased with increasing compression temperature and time. Compression by the CSC method at $160^{\circ}C$ for 40 min was the optimum treatment.

• Journal of the Korean Wood Science and Technology
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• v.50 no.4
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• pp.272-282
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• 2022

The essential oil extracted from Citrus × natsudaidai (Yu. Tanaka) Hayata peels is known to have various biological properties. However, the chemical composition of essential oil is influenced by the ripening stages of fruits, which then affects related biological activities. This study investigates the antioxidant activities of essential oils extracted from Citrus × natsudaidai peels at different ripening stages (immature, mature, and overripe). The essential oils were extracted using the hydro-distillation method. As a result of gas chromatography-mass spectrometry (GC-MS) analysis, d-limonene was dominant and was increased as matured. However, 𝛄-terpinene was decreased. The antioxidant properties and their total phenolic content (TPC) were influenced by the ripening stages. The TPC was highest in the immature stage of essential oil (1,011.25 ± 57.15 mg GAE/100 g). 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was excellent in the immature stage (EC₅₀ = 15.91 ± 0.38 mg/mL). 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity was superior in overripe stage (EC₅₀ = 20.43 ± 0.37 mg/mL). The antioxidant activity measured using ferric reducing antioxidant power (FRAP) assay showed higher values for the essential oils in immaturity (1,342.37 ± 71.07 mg Fe²⁺/100 g). Comprehensively, the essential oil in the immature stage showed the best antioxidant activity. Finally, knowing the chemical composition and antioxidant activity at different ripening stages will provide data for selecting the right fruit.

• Journal of Korean Society of Forest Science
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• v.83 no.1
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• pp.38-49
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• 1994

To investigate the effects of national forest management on the regional community, the inter-relationship between the local communities and neighbouring forest owned by the state was surveyed in the three locations, namely pyungchang-gun, Bonghwa-gun, and Kwangyang-gun, which have a large area of national forest. The effect of national forest management on the local community was different depending upon the relationship between the local community and the national forest, the resource base and infrastructure and facilities installed within the national forest. The major contribution of the national forest to regional society is the provision of land resources, forest products, employment opportunities, and social functions of forest. The supply of land resource from the national forest has been increasing steadily due to the increase in demand for public facilities. About one quarter of household income in the forest villages surveyed came out of the sales of forest products, mainly non-timber products. Due to the low level of forest operations for timber production, there are very limited opportunities of employment provided by the national forest. And the use of forest roads by local residents was also to a limited extent. Therefore, it is suggested that the national frosts should be managed such that help to revive the economy of local communities which are disadvantaged in the national investment priority due to the low economic returns.

• Journal of Forest and Environmental Science
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• v.14 no.1
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• pp.157-164
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• 1998

• New & Renewable Energy
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• v.18 no.3
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• pp.1-9
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• 2022

This study analyzed the anticipated supply-and-demand of forest biomass energy (through wood pellets) until 2050, in South Korea. Comparing the utilization rates of forest resources of five countries (United Kingdom, Germany, Finland, Japan, and S. Korea), it was found that S. Korea does not nearly utilize its forest resources for energy purposes. The total demand for wood pellets in S. Korea (based on a power generation efficiency of 38%) was predicted to be 3,629 and 4,371 thousand tons in 2034 and 2050, respectively. The anticipated total wood pellet power generation ratio to target power consumption is 1.13% (5,745 GWh), 1.17% (6,336 GWh), and 1.25% (7,631 GWh) in 2020, 2030, and 2050, respectively. Low value-added forest residues left unattended in forests are called "Unused Forest Biomass" in S. Korea. From the analysis, the total annual potential amount of raw material, sustainably collectible amount, and available amount of wood pellet in 2050 were estimated to be 6,877, 4,814, and 3,370 thousand tons, respectively. The rate of contribution to Nationally Determined Contributions was up to 0.64%. Through this study, the authors found that forest biomass energy will contribute to a carbon neutral society in the near future at the national level.