• Applied Biological Chemistry
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• v.35 no.5
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• pp.410-414
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• 1992

Endoinulase from Streptomyces sp. S56 was immobilized by adsorption on DEAE-cellulose in 0.01 M citrate-sodium phosphate buffer, pH 6.0 and the properties of immobilized and free enzymes were investigated. The immobilized enzyme preparation, having 40 inulase activity units per dried matrix, revealed the maximal activity at $pH\;4.5{\sim}5.5$ and $55{\sim}60^{\circ}C$ and were most stable at pH 6 and 45^{\circ}C$. The immobilization caused a drop in optimum pH and affinity toward inulin, a slight increase in optimum temperature, an important increase in thermal stability and maximum reaction velocity. The immobilized endoinulase hydrolyzed the tuber extract of jerusalem artichoke and inulin, mainly into fructose and inulobise, degrading 63 and 78% of the total sugar respectively, within 48 hrs in batch reactor.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.13-27
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• 2011

This paper presents an investigation of the structural stability of cable-stayed bridges, using geometric nonlinear finite-element analysis and considering various geometric nonlinearities, such as the sag effect of the cables, the beam-column effect of the girder and mast, and the large displacement effect. In this analytic research, a nonlinear frame element and a nonlinear equivalent truss element were used to model the girder, mast, and cable member. The live-load cases that were considered in this research were assumed based on the traffic loads. To perform reasonable analytic research, initial shape analyses in the dead-load case were performed before live-load analysis. In this study, the geometric nonlinear responses of the cable-stayed bridges with different cable arrangement types were compared. After that, parametric studies on the characteristics of the structural stability in critical live-load cases were performed considering various geometric parameters, such as the cable arrangement type, the stiffness ratios of the girder and mast, the area of the cables, and the number of cables. Through this parametric study, the effect of geometric shapes on the structural stability of cable-stayed bridges was investigated.

• Korean Journal of Microbiology
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• v.30 no.2
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• pp.71-77
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• 1992

A 50 KD metalloprotease of Serratia marcesrens ATCC 21074 was purified by ammoniumsulfate precipitation. DEAE-cellulose ion exchange chromatography, and sephadex ti-100gel filtration. Optimal pH and temperature of enzyme were pH 8.0 and 37"C, respectively.This enzyme was stable in the ranges of 10-37$^{\circ}$C and pH 5.0--11.0. Thermal denaturationwas investigated by differential scanning calorimetry. Onset temperature of denaturationand endothermic peak temperature were 376$^{\circ}$C and 43.2"C. re:,pectively. The denaturationenthalpy was -8.4mJimg. The purified metalloprotease was ri.sistant to autodigestion for24 hr at 30$^{\circ}$C. Metalloprotease in culture supernatant was also resistant to autodigestionin this conditions. Heat-denatured enzyme. however. was rapidly digested by the nativeenzyme. The metalloprotease was stable to proteolytic digestion by mammalian proteasessuch as trypsin. a-chymotrypsin, and elastase. But the enzyme was easily digested bybacterial protease. thermolysin.bacterial protease. thermolysin.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.4
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• pp.160-166
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• 2019

Cerium oxide ($CeO_2$, often called as Ceria) is one of the valuable rare earth oxide materials, which has been widely used for high temperature applications such as solid oxide fuel cells, automotive three-way catalysts and oxygen storage capacity. Considering those application, it is important to improve high redox and thermal stability with high surface morphology because the high surface area of $CeO_2$ could improve the catalytic reactivity at high temperature conditions. Herein we successfully fabricated hierarchical flower-like $CeO_2$ deposited via controlling pathway of precipitation reaction to supply carbonate ion lead to the flower-like morphology. The hexagonal lattice system of precipitated precursor shows better thermal stability then orthorhombic one during thermal cycling condition.

• Korea Trade Review
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• v.43 no.1
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• pp.177-197
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• 2018

This paper aims to analyze the effects of external uncertainty on the entry modes decision of multinational firms. On the basic assumption that the entry modes of the firms are dependent on ex-ante or ex-post perceived risk, we empirically analyzed the impacts of perceived risk factors on the investment patterns of firms. We found that the larger the population, the higher the level of GDP per capita, and the larger the trade volume as a ratio of GDP resulted in increased M&A FDI and greenfield FDI. The economic growth rate variables were found to be significantly positive effect on only greenfield entry mode. Regarding the main variables, lower levels of corruption and increased stability regarding political issues resulted in the host country receiving increased M&A investment. However, we found only a positive statistical significance of the political stability variable on the explaining greenfield FDI. Results show that M&A entry mode is affected by both corruption and political instability level. However, the greenfield FDI featuring sunk costs, seems more responsive to political instability.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.446-452
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• 2009

The behavior of a one-step fixed bed reactor which directly synthesizes dimethyl ether(DME) from Natural Gas was simulated. In the reactor, the prevention of the occurrence of hot spots which can cause deactivation of catalysts is pivotal, since methanol synthesis and dehydration reaction involved in the synthesis of DME are highly exothermic. Therefore, we simulated and compared performance of the reactor with counter-current cooling and pool boiling system that can be applied to a commercial plant. As a result, we found that counter-current cooling system is more effective in terms of CO conversion and DME productivity. However, pool boiling system can operate in a small temperature gradient that can decrease problems caused by hot spot. And, the system can operate in a safer range.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.309-310
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• 2003

활성탄소 (activated carbons, ACs)는 넓은 비표면적을 가지고 있어 흡착용량이 크며, 발달된 미세공을 가지고 있기 때문에 오염물질의 제거능력이 높을 뿐만 아니라 경제적, 환경 친화적인 측면에서도 유리하다. 특히 섬유화된 할성탄소섬유 (activated carbon fibers, ACFs)는 균일한 세공이 표면에 노출되어 있어 흡착속도가 빠르며, 안정성과 재생성이 좋고 섬유상이기 때문에 가공이 용이하며 직포, 부직포, 시트 등의 형태로 만들어져 용매회수, 공업제품의 정제, 오폐수의 처리시설, 소각시설의 유해 배기가스의 흡착등에 널리 사용되고 있다.[1,2] (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.308-309
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• 2003

악취란 황화수소, 메르캅탄류, 아민류, 기타 자극성이 있는 기체상 물질이 사람의 후각을 자극하여 불쾌감과 혐오감을 주는 냄새로서 사람에게 심리적.정신적 피해를 주는 감각오염이라 할 수 있다. 악취 유발물질을 비롯하여 대기중으로 배출된 오염물질의 거동은 오염물질의 물리ㆍ화학적인 특성뿐만 아니라, 기온, 풍향, 풍속, 혼합고, 대기안정도 등 다양한 국지 기상인자의 영향을 받게된다. 특히 악취유발물질은 다른 대기오염물질과는 달리 미량에서도 불쾌감을 주고 그 원인물질이 상당히 많을 뿐만 아니라 물질간의 반응기작이 매우 복잡하다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.419-420
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• 2001

최근 산업설비 및 기타 시설에서 배출되는 유해가스의 배출허용 기준이 계속 강화되고 있으며 그 중에서도 NOx는 SOx와 함께 대기오염의 주된 원인으로 작용하고 있다. 국내에서도 이들 유해가스를 제거하기 위한 플라즈마 적용기술이 활발히 연구되었으며, 일부 기술은 상용화 단계에 있다. NOx 제거에 있어서 펄스 코로나 방전에 의한 전자의 생성은 유입되는 가스 및 공기에 충돌하여 반응성이 큰 다량의 이온, 원자 및 radical(N, O, OH, $O_3$등)을 생성한다. (중략)

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.514-516
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• 2000

게임이나 가상 현실에서의 대화형 처리에서는 다관절체의 동작 생성을 실시간에 비교적 사실적으로 처리되어야 할 필요성이 커지고 있다. 본 논문에서는 복잡한 계산이나 선형 시스템의 풀이 과정이 불필요한, 다관절체의 동작을 비교적 사실적으로 간단하고, 빠르게 생성하는 방법을 제안한다. 이 방법은 다관절체의 동역학적 움직임과 기하학적 제약 조건들을 이용하여, 실제와 유사한 동작을 빠르게 생성할 수 있음을 보인다. 특히, 대화형 시스템에서는 사용자의 요구에 실시간으로 응답을 줄 수 있고, 환경을 설정하는 물리량들과 가상 공간의 환경 요인들을 다양하게 변화시키더라도 적응적으로 반응하는 안정적인 동작을 생성할 수 있다.