• Polymer(Korea)
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• v.38 no.1
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• pp.31-37
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• 2014

To prepare biomass based nylon 6,5 copolymers, ${\varepsilon}$-caprolactam and 2-piperidone, the monomers of nylon 6,5 copolymers, were synthesized respectively from lysine and 5-aminovaleric acid which were produced from glucose by the fermentation process. The copolymers were then polymerized by the anionic ring opening polymerization of them at $40^{\circ}C$, using potassium tert-butoxide as a catalyst and acetyl-2-caprolactam and carbon dioxide as initiators. The prepared copolymers were characterized with various analytical methods: their viscosity molecular weight ($M_{\eta}$) was as high as 30000 g/mol and polymerization yield was over 50%, and it was found that they were semi-crystalline polymers having melting point at $165^{\circ}C$ which was much lower than its thermal degradation point, $250^{\circ}C$. These polymers were expected to have good thermal processability and application fields.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.88-94
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• 2021

The seaweed, Gracilaria verrucosa (red seaweed) was fermented to produce bioethanol. Optimal thermal acid hydrolysis conditions were determined as 200 mM H₂SO₄ and 10% (w/v) seaweed slurry at 130℃ for 60 min yielding 47.5% of pretreatment efficiency (E_p). After the thermal acid hydrolysis, enzymatic saccharification was carried out with 16 U/ml Viscozyme L, Cellic CTec2 or mixture of Viscozyme L and Cellic CTec2 to G. verrucosa hydrolysates. Enzymatic saccharifications with Viscozyme, Cellic CTec2 or mixture of those yielded 7.3 g/l glucose with efficiency of saccharification, E_s = 34.9%, 11.6 g/l glucose with E_s = 64.4% and the mixture of those 9.6 g/l glucose with E_s = 56.6%, respectively. Therefore, based on the E_s value, Cellic CTec2 was selected for the optimal enzyme for enzymatic saccharification of G. verrucosa hydrolysate. The ethanol productions with non-adapted S. cerevisiae CEN-PK2 (wild type) and S. cerevisiae CEN-PK2 with adaptive evolution to galactose produced 8.5 g/l ethanol with Y_EtOH = 0.19 and 21.5 g/l ethanol with Y_EtOH = 0.50 at 144 h, respectively. From these results, the ethanol production by S. cerevisiae with adaptive evolution showed high concentration of ethanol production using G. verrucosa as a substrate.

• Cross-Cultural Studies
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• v.49
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• pp.181-199
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• 2017

One of the most lasting and influential projects for radical reform of Korean universities is a discourse on networking national and public universities. The discourse, proposed with a level equalization of universities as its ideological basis has raised various discussions and suggestions in the past 20 years. It was proposed as a fundamental solution to the 'disastrous' hierarchical structure of universities and 'hellish' entrance exam competition. This paper aims at reexamining the efficacy of its ideological proposition and its practicability at the present time in reference to such foreign cases, which have worked as model cases for this discourse: the reformation of the University of Paris and the California master plan for higher education in the 1960s. The two different contexts, however, should be considered in applying the cases to Korean university reform. 1) The foreign cases of united universities were formed 'naturally' in the expanding phases of higher education while the Korean project pursued 'artificially' in the midst of reconstructing process. 2) The foreign cases had an overall influence on education in general as most of the universities in those countries were public or national, while the effect of Korean project will be very limited as most of the university students attend private universities. Besides those differences, the new situations surrounding universities such as globalized competitiveness and technological innovation is making the idea of standardization of universities obsolete. Korean university reform should not be centered on the integration of universities but on their characterization and enhance the specific strengths of each group of universities.

• Journal of Climate Change Research
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• v.4 no.1
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• pp.41-49
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• 2013

Recent findings have revealed that black carbon is one of the substantial materials affecting climate change along with greenhouse gases. Usually, black carbon is generated by incomplete combustion of biomass and deposited on snow and ice surface, resulting in increasing adsorption of radiant energy and accelerating ice melting. However, it is still questionable what the emission characteristics of black carbons from biomass combustion is. We investigated the emission characteristics of black carbon generated from a wood stove in this study. We found that the emission of black carbon was highly dependent upon combustion temperature and the amount of combustion air supplied. The emission factors were 1.01 g-BC/kg-Oak for fireplace wood burning under incomplete combustion, 0.37 g-BC/kg-Oak for fireplace wood burning under complete combustion and 0.29 g-BC/kg-Oak for small wood-stove burning.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.311-316
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• 2019

Japanese anise (Illicium anisatum L.) leaves and twigs were extracted with 50 % aqueous acetone three times. After filtration, the extracts were fractionated with n-hexane, chloroform, ethyl acetate and $H_2O$, and then freeze dried after condensation. Then antioxidation and antiviral activity were evaluated on each fractions. In the antioxidative activities, the results indicated high activity in the EtOAc soluble fraction of the leaves and the EtOAc and $H_2O$ soluble fractions of the twigs. It showed much higher antioxidative value compare to the controls, BHT and ${\alpha}$-tocopherol. In the antiviral activities, the all fractions were negative effects in HRV 1B and EV 71, but good in Influenza PR8. The activities of the crude extracts of the leaves and twigs showed more than 80% activity at the concentration of $10{\mu}g/mL$ and $50{\mu}g/mL$, respectively, and the activities of the EtOAc and $H_2O$ soluble fractions were close to 80%. Based on the above results, the extracts of Japanese anise may be applied for one of the natural biomass sources that can be used as an antioxidant and an antiviral substance.

• Journal of Life Science
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• v.29 no.1
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• pp.90-96
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• 2019

The objective of this study was to evaluate the potential of Diospyros malabarica stem extract, a natural materials, in oral health material. With this aim in mind, thin layer chromatography (TLC), TLC-bioautography, high-performance liquid chromatography (HPLC), electrospray ionization-mass spectrometry (ESI-MS), scanning electron microscopy (SEM), and real-time qPCR were performed. The antibacterial activity of D. malabarica stem extract against Streptococcus mutans KCTC3065 was confirmed in an n-hexane fraction with low polarity. The molecular weight of the antibacterial compound was estimated to be 188 by ESI-MS analysis. The inhibitory effects of the extract on biofilm formation and gene expression related to biofilm formation of S. mutans were determined by SEM and real-time PCR analysis. The extract inhibited the formation of S. mutans biofilms at D. malabarica stem extract concentrations of 1 mg/ml, as shown by SEM. The real-time PCR analysis showed that the expression of the gtfC gene, which is associated with biofilm formation, was significantly decreased in a dose-dependent manner. Based on the above results, it can be concluded that D. malabarica stem extracts, a natural materials, can be used in oral health products to suppress the formation of biofilms by inhibiting tooth adhesion of S. mutans, a causative agent of dental caries.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.4
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• pp.23-33
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• 2020

Marine algae(Macro algae) are easily bio-degradable, and by-products are available as feed and fertilizer. The biomass of marine algae has higher CO2 absorption capacity than the wood system, and is highly valuable in use due to its fast growth speed and wide cultivation area without special cost for raw material production. In 2018, Marine algae production was 1,722,486ton, such as Saccharina japonica, Undaria pinnatifida and Porphyra tenera, the large amounts of by-products have been generated in the food processing facilities for commercialization. In this study, Saccharina japonica, Undaria pinnatifida were collected in the south coast region and Porphyra tenera was collected in the west coast region. The theoretical methane potential and biochemical methane potential(BMP) were analyzed, and Modified Gompertz model and Parallel first order kinetics model were adopted for the interpretation of the cumulative methane production curves. The theoretical methane potential of Saccharina japonica, Undaria pinnatifida and Porphyra tenera were 0.393, 0.373 and 0.435 N㎥/kg-VS, respectively. BMP obtained by the Modified gompertz model 0.226, 0.227, and 0.241 N㎥/kg-VS for Saccharina japonica, Undaria pinnatifida and Porphyra tenera, respectively. And BMP obtained by the Parallel first order kinetics model were 0.220, 0.243, and 0.240 N㎥/kg-VS for Saccharina japonica, Undaria pinnatifida and Porphyra tenera, respectively.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.715-721
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• 2011

This study was conducted to estimate aboveground biomass and nitrogen storage potential of tree species-eight clones of a poplar and hybrids, one clone of Salix alba L., dawn redwood (Metasequoia glyptostroboides Hu and W.C. Cheng), yellow poplar (Liriodendron tulipifera L.), Okamoto maple (Acer okamotoanum Nakai), and pin oak (Quercus palustris $M{\ddot{u}}nchh.$)- after treating with liquid pig manure. Stems showed the highest percentage of aboveground biomass, and followed by branches and leaves. Nitrogen content in aboveground biomass components was the highest in leaves, and followed by branches and stems. Average aboveground biomass production was higher in the clones and species treated with manure than those of not treated, 30 ton/ha and 16 ton/ha, respectively. In the manure-treated site, clone 'Dorskamp' of Populus deltoides${\times}$Populus nigra showed the highest aboveground biomass (48.3 ton/ha). Average nitrogen storage potential was superior in the clones and species treated with manure than those of not treated, 159 kg/ha and 90 kg/ha, respectively. Clone 'Dorskamp' also showed the greatest nitrogen storage potential (286.5 kg/ha) among tested tree species. Therefore, 'Dorskamp' is the most suitable clone for treating liquid pig manure, but additional studies are needed to determine any damages or tolerance from the treatment.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.101-110
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• 2021

Interactions between microalgae and heterotrophic bacteria are common in natural environments. This study investigated the effect of heterotrophic bacteria on the activity of the photosynthetic eukaryotic alga Chlorella sp. MF1907 when cocultured. A total of 31 heterotrophic bacterial isolates belonging to different genera were cocultured with MF1907. Interactions of the alga with Agromyces, Rhodococcus, Sphingomonas, Hyphomicrobium, Rhizobium, and Pseudomonas were positive, while those with Burkholderia, Paraburkholderia, Micrococcus, Arthrobacter, Mycobacterium, Streptomyces, Pedobacter, Mucilaginibacter, Fictibacillus, Tumebacillus, Sphingopyxis, and Erythrobacter were negative (p < 0.05). A turnover experiment demonstrating a switch from heterotrophic to autotrophic activity of MF1907 was performed using 16 isolates exhibiting apparent effects (positive, negative, or neutral). Compared with the results of the coculture experiment, eight isolates exhibited the same outcomes, while the others did not. Consistently, Pseudomonas and Agromyces showed a remarkable positive effect on MF1907 activity, and Burkholderia, Streptomyces, and Erythrobacter had a marked negative effect. Our results suggest that it may be possible to use the isolates for controlling populations of microalgae in natural and engineered environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.401-408
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• 2021

Supplies of wood chips for fuel tend to increase owing to energy decentralization and new renewable energy policies. This study suggests a technical method that is necessary in order to supply heating energy to rural regions by using wood chips for fuel. Therefore, this study investigates the effects of natural drying methods for eight months by installing a drying facility with natural ventilation capable of loading 10 tons of wood chips, and which derive a natural drying method based on this to meet the quality standards of wood chips for fuel. The study results confirm that it is possible to produce wood chips for high-quality fuel with water content at 20% or less after around 90 days of drying, provided that a drying facility with natural ventilation is equipped with materials that can be procured easily in rural regions. It is also possible to block the proliferation and fermentation of molds that affect the quality of wood chips, provided that intake and exhaust systems adhering to standards are equipped.