• Journal of the Korean Ceramic Society
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• v.55 no.4
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• pp.392-399
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• 2018

$C_f/SiC$ composites were prepared via a process combining chemical vapor infiltration (CVI) and precursor infiltration pyrolysis (PIP), wherein silicon carbide matrices were infiltrated into 2.5D carbon preforms. The obtained composites exhibited porosities of 20 vol % and achieved strengths of 244 MPa in air at room temperature and 423 MPa at $1300^{\circ}C$ under an Ar atmosphere. Carbon fiber pull-out was rarely observed in the fractured surfaces, although intermediate layers of pyrolytic carbon of 150 nm thickness were deposited between the fiber and matrix. Fatigue fracture was observed after 1380 cycles under 45 MPa stress at $1000^{\circ}C$. The fractured samples were analyzed by transmission electron microscopy to observe the distributed phases.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.459-467
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• 1989

When the sufactants are dissolved in water, they associate to form micelles and solubilize oil inside the micelle to form swollen micelles. Although spherical aggregates like micelles and swollen micelles occupy the same regions in the phase diagram of water-oil-surfactant systems, they are treated in different viewpoint for the formation of such aggregates. Hence a unified thermodynamic formalism for the formation of such structure is presented in this study. In all cases, the to ideal solution theory is applied for dilute system and the energy of formation is expressed as the sum of hydrophobic interaction energy and surface energy due to surfactant film. From the model, critical micelle concentration (CMC), average aggregation number, and solubilization ratio are predicted and compared with the known experimental observation.

• Annual Conference on Human and Language Technology
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• 2008.10a
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• pp.42-47
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• 2008

1980년대 중반부터 지난 20여 년간 구축해 온 영어 워드넷(PWN)은 인간의 심상어휘집을 재현하려는 목적으로 개발되기 시작하였으나, 그 활용 가능성에 주목한 것은 자연언어처리와 지식공학 분야다. 컴퓨터 매개 의사소통(CMC), 인간-컴퓨터 상호작용(HCI)에서 인간 언어를 자연스럽게 사용하여 필요한 정보를 획득하기 위해서는 의미와 지식의 처리가 필수적인데, 그 해결의 실마리를 어휘라는 실체를 가진 언어단위에서 찾을 수 있기 때문이다. 이후 전 세계적으로 약 50개 언어의 어휘의미망이 PWN을 참조모델로 구축되어 다국어처리의 기반을 제공할 뿐 아니라, 시맨틱 웹 이후 더욱 주목 받고 다양한 방식으로 활용되고 있다. 본고는 PWN을 참조 모델로 2004년부터 2007년까지 구축한 한국어 어휘의미망 KorLex 1.5를 소개하는 데 있다. 현재 KorLex은 명사, 동사, 형용사, 부사 및 분류사로 구성되며, 약 13만 개의 신셋과 약 15만 개의 어의를 포함하고 있다.

• Macromolecular Research
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• v.13 no.5
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• pp.397-402
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• 2005

To explore the potential of shell crosslinked micelle (SCM) as a drug carrier, the drug release behavior of poly($\varepsilon$-caprolactone)-b-poly(acrylic acid) (PCL-b-PAA) SCMs was investigated. PCL-b-PAA was synthesized by ring opening polymerization of $\varepsilon$-caprolactone and atom transfer radical polymerization of tert-butyl acrylate, followed by selective hydrolysis of tert-butyl ester groups to acrylic acid groups. The resulting amphiphilic polymer was used to prepare SCMs by crosslinking of PAA corona via amidation chemistry. The drug release behavior of the SCMs was studied, using pyrene as a model drug, and was compared with that of non-crosslinked micelles, especially below the critical micelle concentration (CMC). When the shell layers were crosslinked, the drug release behavior of the SCMs was successfully modulated at a controlled rate compared with that of the non-crosslinked micelles, which showed a burst release of drug within a short time.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.38-46
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• 2005

This study was focused on the optimum culture condition in CMCase, FPase and xylanase activities of two fungal strains that secret extracellular enzymes for using enzymatic deinking agent to old newsprint. The results of this study were as follows. When Fusarium pallidoroseum was grown on the medium, containing of rice bran+xylan $2.0\%,\;peptone\;0.6\%,\;KH_2PO_4\;0.075\%\;and\;MnSO_4\;0.06\%\;with\;pH\;9.0,\;at\;29^{\circ}C$ for 6 days, the quantitative degree of extracellular enzyme production was the highest. Optimum culture condition for Aspergillus niger was pH 5.0, $27^{\circ}C$ incubating temperature and 7 days incubation period on liquid medium, containing of CMC+xylan $2.5\%,\;yeast\;extract\;0.4\%,\;K_3PO_4\;0.05\%\;and\;CaCl_2+FeSO_4\;0.08\%$. Aspergillus niger was fairly higher FPase and xylanase activities than Trichoderma reesei ATCC 28217.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.83-86
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• 1998

1. Introduction : Low molecular harmful organics such as 1-naphthol and phenol are widely used in industries, and pose serious environmental problems. Wastewater containing low molecular harmful organics may be ejected from various sources including metal-plating industries, circuit-board manufacturing process, photographic and photo-processing industries, refineries and metal-tailing leachate. The pollution of nation harbors, waterways and ground water resources with these organics has reached critical portions, and might also give hazardous influence on human health. Micellar enhanced ultrafiltration(MEUF) is a recently developed process to remove dissolved organics and/or heavy metals present in small or trace quantities from aqueous solution. In this system, the fatal defect is leakage of surfactants especially at low concentration below CMC(critical micelle concentration), which becomes a secondary pollution. Our group proposed to use biosurfactant and polymeric micelle to solve problems mentioned above. In this study we investigated a modified MEUF using PEO-PPO-PEO (polyethyleneoxide-polypropyleneoxide-polyethyleneoxide) block copolymers for the removal of organic solutes such as 1-naphthol and phenol from aqueous wastewater. We proposed PEO-PPO-PEO block copolymers as new surfactants for forming micelles in MEUF, and investigated the solubilization characteristics and efficiency for the removal of 1-naphthol and phenol. PEO-PPO-PEO block copolymers are, environmentally mild and safe as biosurfactants.

• Journal of Applied Biological Chemistry
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• v.42 no.3
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• pp.107-112
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• 1999

A carboxymethyl-cellulase (CMCase) was purified from the culture supernatant of Bacillus sp. KD1014 by ultrafiltration, ammonium sulfate precipitation, and a series of chromatography on QAE-Sephadex A-50, hydroxylapatite and Sephadex G-75. The purified CMCase was a single protein of 32 kDa, showed an optimum activity at $60^{\circ}C$ and pH 6.0, and had a half-life of 23 min at $70^{\circ}C$. The enzyme activity was not influenced by metal ions such as $Mg^{2+},\;Fe^{3+},\;K^+,\;Zn^{2+}$, and $Cu^{2+}$ at a concentration of 1.0 mM, partially inhibited by $Mn^{2+}$ and $Ag^+$, and significantly inhibited by pentachlorophenol (PCP). The purified enzyme showed a 3.9-times higher activity on lichenan than on CMC, but hardly cleaved xylan, starch, avicel, laminarin, filter paper and levan. The results of activity staining of the purified enzyme separated by native and denaturing gel electrophoresis suggested that the CMCase might exist in dimeric, oligomeric or aggregated form as well as in monomeric form. The enzymatic cleavage products from cellotetraose indicated that the CMCase possessed transglycosylation activity.

• Journal of Microbiology and Biotechnology
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• v.9 no.4
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• pp.518-521
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• 1999

Bacillus sp. 79-23 spores were irradiated with $^{60}Co$ gamma-rays at doses ranging from 0.5 to 5 kGy. Following gamma-irradiation, seven mutant strains were isolated by scoring the halo sizes formed around the colonies grown on LB agar plates containing 4% carboxymethylcellulose (CMC) and trypan blue. The mutant strains showed a 1.5 to 2-fold increase in carboxymethylcellulase (CMCase) activity over the parent strain. Wheat bran acted as an effective inducer for CMCase production in the parent and mutant strains. Mutant strains 68 and 70 were identified as exhibiting higher CMCase activities than those of other mutants in LB media both with and without 3% wheat bran. In addition, these strains seem to produce substantially lower amounts of capsular materials, whereas the parent strain produced large amounts of them in both liquid and solid LB media. In flask cultures, the CMCase production by mutants 68 and 70 reached maximum levels of 17.5 unit/ml and 15.7 unit/ml, respectively, in an LB medium containing 3% wheat bran.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.440-446
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• 2014

The carbohydrate-binding module (CBM) is an important domain of most cellulases that plays a key role in the hydrolysis of cellulose. The neutral endoglucanase (EG1) gene was reconstructed. A redesigned endoglucanase, named EG2, was constructed with a CBM containing a linker from Corticium rolfsii (GenBank Accession No. D49448). The redesigned EG genes were expressed in Escherichia coli, and their characteristics are discussed. Results showed that the degradation of cellulose by EG2 was about double that by EG1. The specific activities of EG1 and EG2 were tested under optimal conditions, and EG2 had higher activity ($169.1{\pm}2.74$ U/mg) toward CMC-Na than did EG1 ($84.0{\pm}1.98$) in the process of cellulose degradation. The optimal pH and temperature, pH stability, and heat stability of EG1 and EG2 were similar. Results indicated that the CBM plays an essential role in the hydrolysis of cellulose. We can improve EG's catalytic power by adding the CBM from Corticium rolfsii.

• Journal of the Korean Applied Science and Technology
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• v.6 no.1
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• pp.51-57
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• 1989

A series of four sodium ${\alpha}-sulfo$ fatty vinyl ester oligomers including sodium ${\alpha}-sulfo$ lauric acid vinyl ester oligomer, sodium ${\alpha}-sulfo$ myristic acid vinyl ester oligomer, sodium ${\alpha}-sulfo$ palmitic acid vinyl ester oligomer and sodium ${\alpha}-sulfo$ stearic acid vinyl ester oligomer were examined for surface activities such as surface tension, foaming power, foam stability, emulsifying power, dispersion effect, solubilization of orange OT. The critical micelle concentration(CMC) was also evaluated. Consequently, these sodium ${\alpha}-sulfo$ fatty acid vinyl ester oligomers were shown to have a good cohesive power and dispersion effect.