• Journal of the Korean Wood Science and Technology
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• v.40 no.6
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• pp.389-396
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• 2012

In this study, we investigated the kinetics of acid-catalyzed hydrolysis of xylan over a 60 min at $120^{\circ}C$. Sulfuric, oxalic and maleic acids were used as acid catalyst for hydrolysis. The calculated degradation rate constants ($k_1$) showed a correlation with the acid concentration, meaning that the stronger the acid, the higher the xylan degradation rate. Among sulfuric, oxalic and maleic acid catalyzed hydrolysis, the xylan degradation rate to xylose was highest with sulfuric acid. At equivalent solution pH, acid catalyzed hydrolysis was proportional to $H^+$ concentration. The $k_1$ of dicarboxylic acid such as oxalic and maleic acid was higher than that of sulfuric acid at same pH values during hydrolysis.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.205-212
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• 2010

This study was carried out to investigate the characterization of aerogel made by holocellulose, the thermal properties of the aerogel, and its shapes and porous structures. The aerogel was made by holocellulose through the gelation in alkali hydroxide-urea solution and freeze drying processes. Holocellulose aerogel had porous structure such as net or sponge. The density of holocellulose aerogel was 0.04 g/$cm^3$, and the specific surface area 145.3 $m^2$/g. Although thermal degradation occurred in the range of $210{\sim}350^{\circ}C$, significant thermal degradation occurred at low temperature with low heating rate, Micropore volume was sharply increased with low heating rate. Holocellulose aerogel char obtained by carbonization with $900^{\circ}C$ and $0.5^{\circ}C$/min. heating rate had the highest surface area, 656.7 $m^2$/g. The deformed and irregular structures of holocellulose aerogel chars due to the thermal degradation were observed in SEM.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.5-12
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• 2006

Degradation performance of environmentally friendly plastics that can be disintegrated by combination of sunlight, microbes in soil, and heat produced in landfills was evaluated for use in industries. Two multi-degradable master batches (MCC-101 and MCC-102 were manufactured, separately mixed with polyethylene using film molding machine to produce 0.025 mm thick films, and exposed to sunlight, microbes, and heat. Low- and high-density polyethylene (LDPE and HDPE) films containing MCC-101 and MCC-102 became unfunctional by increasing severe cleavage at the surface and showed high reduction in elongation after 40 days of exposure to ultraviolet light. LDPE and HDPE films showed significant physical degradation after 100 and 120 days, respectively, of incubation at $68{\pm}2^{\circ}C$. SEM images of films cultured in mixed mold spore suspension at $30^{\circ}C$ and 85% humidity for 30 days revealed accelerated biodegradation on film surfaces by the action of microbes. LDPE films containing MCC-l01 showed absorption of carbonyls, photo-sensitive sites, at $1710\;cm${-1}$ when exposed to light for 40 days, whereas those not exposed to ultraviolet light showed no absorption at the same frequency. MCC-101-based LDPE films showed much lower $M_w$ distribution after exposure to UV than its counterpart, due to agents accelerating photo-degradation contained in MCC-101.

• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.71-80
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• 2003

The lignin degrading fungi were isolated from decayed woods and fruiting bodies gathered in forest area. Lignin degradation ability was investigated by Klason lignin of microbial treated pine wood. Among selected fungi, CJ-6 had 49.48% Klason lignin loss which was greater than 40.58% shown by Trametes versicolor that it is known as a typical lignin degrading fungus. Also, the biodegradation process and morphological features of degraded pine wood by selected fungi were observed with the scanning electron microscope. At the stage of 20 days incubation, mycelia invasion was observed without any failure of wood structure. At 60 days, wood decay was gone in some degree and one part of tracheid and ray wall was destroyed. At 100 days, tracheid wall was severely destroyed, and distinction between ray cell was difficult as cell wall was decayed much.

• Korean Journal of Environment and Ecology
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• v.28 no.2
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• pp.171-181
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• 2014

This study was performed to prevent deforestation and forest degradation and vitalize REDD+ program through suitable site analysis at the 16 districts of South Korea. For this, we worked out profit potential, opportunity cost, carbon credits through making it use of conception of the Forest Carbon Index. As a results, Gyeonggi-do, Incheon Metropolitan City, Seoul Metropolitan Government, Daegu Metropolitan City, Gwangwon-do included in the top 5 among the 16 districts of South Korea. In case of Gyeonggi-do as best suitable site, reduction of carbon emission was best high due to reduction area of deforestation. And profit potential was also high in accordance with practice of REDD+ program. Furthermore, we proposed four plans to activate REDD+ program in South Korea on the basis of the results.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.152-158
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• 2007

Micromorphological and chemical characteristics of living Castanea spp. and Tamarix spp. attacked by a brown-rot fungus were examined. Micromorphological features of brown-rotted hardwood species were similar to those observed in softwoods such as losses in birefringence under polarized microscopy, preferential degradation of $S_2$ layer and cracks in the $S_3$ layer. Thinning of the secondary cell wall in fibers was also observed, although it did not seem to be the main symptom. FT-IR analysis showed that bands assigned to cellulose and hemicelluloses decreased or disappeared, whereas the bands assigned to lignin increased. X-ray diffraction analysis exhibited the decrease of relative crystallinity, indicating that degradation of hardwood by a brown-rot fungus was in the advanced stages.

• Journal of Forest and Environmental Science
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• v.25 no.3
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• pp.177-185
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• 2009

Dryland species and ecosystems have developed unique strategies to cope with low and sporadic rainfall. They are highly resilient and recover quickly from prevailing disturbances such as fires, herbivore pressure and drought. Dryland people have engineered pastoral and farming systems, which are adapted to these conditions and have sustained the livelihoods of dryland people for centuries. In this article, we present the status of potentials and threats to dryland biodiversity and explore options for its conservation and sustainable use. Findings of the research can be summarized as follows: (i) The ecosystem goods and services are highly valued by the community but mechanism for wise use of the resources has disappeared, (ii) forests are under the ownership of the government but the local community is the realistic custodian of the forests through village leaderships and environmental committees; (iii) the immediate major threat to dryland biodiversity held in the forests appears to be the degradation of ecosystems and habitats caused by new and powerful forces of environmental degradation such as large scale irrigation of rice farms, poverty-induced overexploitation of natural resources, and disappearance and ignorance of traditional institutions for management of dryland biodiversity. These new forms of disturbances often overpower the legendary resilience of dryland ecosystems and constitute potentially serious threats to dryland biodiversity. Forests, wetlands and oases all of which are micro hot spots of dryland biodiversity, appear to be particularly vulnerable hence the need to set up some rules and regulations for sustainable utilization of these resources.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.100-108
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• 2007

$\beta$-Glucosidase from Laetiporus sulphureus among the enzymes related to lignocellulosic biomass degradation to sugars for using alternative bioethanol production was characterized. The highest activity of $\beta$-glucosidase was obtained on cellobiose at shaking culture. For the characterization and purification of $\beta$-glucosidase culture solution was concentrated and then purified by FPLC using ion exchange and size exclusion column. According to the results of SDS-PAGE, native PAGE and microfluidic system of purified enzyme, protein band was observed at about 132 kDa. Optimal pH and temperature of purified $\beta$-glucosi-dase were 5.0 and $60^{\circ}C$, respectively. In the kinetic properties of $\beta$-glucosidase on various substrates such as sophorose, gentiobiose and cellobiose, $K_m$ was 0.81, 1.07 and 1.70 mM, respectively.

• Journal of Microbiology
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• v.45 no.6
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• pp.485-491
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• 2007

The effects of biological pretreatment on the Japanese red pine Pinus densiflora, was evaluated after exposure to three white rot fungi Ceriporia lacerata, Stereum hirsutum, and Polyporus brumalis. Change in chemical composition, structural modification, and their susceptibility to enzymatic saccharification in the degraded wood were analyzed. Of the three white rot fungi tested, S. hirsutum selectively degraded the lignin of this sortwood rather than the holocellulose component. After eight weeks of pretreatment with S. hirsutum, total weight loss was 10.7%, while lignin loss was the highest at 14.52% among the tested samples. However, holocellulose loss was lower at 7.81 % compared to those of C. lacerata and P. brumalis. Extracelluar enzymes from S. hirsutum showed higher activity of ligninase and lower activity of cellulase than those from other white rot fungi. Thus, total weight loss and changes in chemical composition of the Japanese red pine was well correlated with the enzyme activities related with lignin- and cellulose degradation in these fungi. Based on the data obtained from analysis of physical characterization of degraded wood by X-ray Diffractometry (XRD) and pore size distribution, S. hirsutum was considered as an effective potential fungus for biological pretreatment. In particular, the increase of available pore size of over 120 nm in pretreated wood powder with S. hirsutum made enzymes accessible for further enzymatic saccharification. When Japanese red pine chips treated with S. hirsutum were enzymatically saccharified using commercial enzymes (Cellulclast 1.5 L and Novozyme 188), sugar yield was greatly increased (21.01 %) compared to non-pre treated control samples, indicating that white rot fungus S. hirsutum provides an effective process in increasing sugar yield from woody biomass.

• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.101-107
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• 2018

We identified the main impacts, drivers, and restoration projects for Atlantic Forest in Northwest of the Rio Grande do Sul State, Brazil. The objective was to analyze the quantity, distribution, and causes of the environmental crimes in 2000-2014. To verify differences between degraded and restored areas, we performed a t-test; ANOVA for the municipalities with more quantity of crimes, simple linear regression analysis for the relationship between sizes of degraded areas and quantity of seedlings planted, and Principal Component Analysis (PCA) for environmental damages categories and population of the municipalities. The main environmental damages found were deforestation outside permanent preservation area (20%) and those related to Permanent Preservation Area (37%). Environmental crimes in these areas fall into two categories: native and exotic vegetation removal (17%), and impediment to natural regeneration (20%). The average size of the degraded areas was $5,359{\pm}526m^2$, while for restored areas was $3,337{\pm}255m^2$. The sizes of the degraded fragments were similar among the five municipalities with the higher number of environmental crimes (ANOVA: p>0.05, F=1.24; df=241). The number of seedlings planted was positively related to the sizes of the degraded fragments (p<0.001, $R^2=0.53$). Segregation between the less and the most populous municipalities was found with the PCA analysis along PC1 (51.7%), while PC2 represented 19.2% of the total variation. The most populous municipalities showed the highest number of environmental crimes, and the majority of degraded areas were recovered by planting native seedlings. Atlantic Forest fragments need to be recognized and preserved as an ecosystem with a unique ecological function by the population and public administration.