• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.168.2-168
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• 1998

No Abstract, See Full Text

• Membrane Journal
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• v.20 no.2
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• pp.87-96
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• 2010

We prepared spherical silica particles by controlling various conditions of emulsion-gel procedure using a lab-scale membrane emulsification system equipped with SPG (Shirasu porous glass) membrane having pore size of 2.6 ${\mu}m$. We determined the effects of process parameters of membrane emulsification (dispersed phase pressure, stabilizer and emulsifier concentration in continuous phase, $H_2O$/TEOS ratio, ratio of dispersed phase to continuous phase) on the mean size and size distribution of silica particles. The increase of the dispersed phase pressure and ratio of dispersed phase to continuous phase led to the increase in the mean size of silica particles. On the contrary, the increase in stabilizer and emulsifier concentration and $H_2O$/TEOS ratio caused the reduction of the mean size of particles. Through controlling these parameters, monodisperse spherical silica particles with about 3 ${\mu}m$ of the mean size were finally prepared.

• Journal of Life Science
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• v.20 no.11
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• pp.1656-1661
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• 2010

Alkaline protease for the hydrolysis of egg yolk protein was immobilized on five carriers - Duolite A568, Celite R640, Dowex-1, Dowex 50W and Silica gel R60. Duolite A568 showed a maximum immobilization yield of 24.7%. Optimum pH for the free and immobilized enzyme was pH 8 and 9, respectively. However, no change was observed in optimum temperature ($50^{\circ}C$). Thermal stability was observed in immobilized enzymes compared to free enzymes. The immobilized enzyme retained 86% activity after 10 cycle operations in a repeated batch process. The effect of flow rate on the stability of enzyme activity in continuous packed-bed reactor was investigated. Lowering flow rate increased the stability of the immobilized enzyme. After 96 hr of continuous operation in a packed-bed reactor, the immobilized enzyme retained 83 and 61% activity when casein and egg yolk were used as a raw materials, respectively.

• Particle and aerosol research
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• v.7 no.1
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• pp.9-19
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• 2011

The effects of different transient loading conditions on xylene removability and bacterial activity were evaluated in the polyurethane (PU) biofilter inoculated with Rhodococcus sp. EH831: BF1 (the control) was operated under continuous and constant loading ($200{\pm}50ppm$); BF2 under continuous and constant loading after a 2-week long-term shutdown; BF3 under discontinuous (8 h on/16 h off on weekdays and a 2 day-shutdown at weekends); and constant loading BF4 under discontinuous and high loading ($700{\pm}300ppm$); and BF5 under continuous and fluctuating loading (high loading for 8 h and low loading ($75{\pm}25ppm$) for 16 h on weekdays and low loading at weekends). Xylene removal efficiencies in the BF1, BF2, BF3, and BF5 were ranged 83-89%, indicating that 2-week long-term shutdown, intermittent or fluctuant loading condition did not significantly influence the biofilter performance. However, discontinuous and high load condition (BF4) caused to deteriorate xylene removability to 52%. Rhodococcus sp. EH831 could be maintained at $10^9{\sim}10^{10}CFU/g-dry$ PU under 5 kinds of loading conditions. The result of polymerase chain reaction-terminal-restriction fragment length polymorphism showed that there was no significant change in bacterial community structures by different loading conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.39-46
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• 2023

In this study, the dynamic behavior of friction bearings of PSC (Pre-Stressed Concrete) box train continuous bridge was numerically analyzed at 10 km/h intervals up to 600 km/h according to the increasing speed of the next-generation high-speed train. A frame model was generated targeting the 40-meter single-span and two-span continuous PSC box bridges in the Gyeongbu High-Speed Railway section. The interaction forces including the inertial mass vehicle model with 38 degrees of freedom and the irregularities of the bridge and track were considered. It was calculated the longitudinal displacement, cumulative sliding distance and displacement speed of the bridge bearings at each running speed so that compared with the dynamic behavior trend analysis of the bridge. In addition, long-term friction test standards were applied to evaluate the durability of friction plates.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.2
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• pp.83-88
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• 2001

The robust linear H(sub)$\infty$ FIR filter, which guarantees a prescribed H(sub)$\infty$ performance, is designed for continuous time-varying systems with unknown cone-bounded nonlinearity. The infinite horizon filtering for time-varying systems is systems is investigated in therms of two Riccati equations by the finite moving horizon.

• Journal of the Korean Institute of Intelligent Systems
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• v.3 no.3
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• pp.19-26
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• 1993

In this paper, we introduce the notion of H-fuzzy esmitopogenous spaces. In section 1, we give the preliminary definitions and some basic results. In section 2, we show that category HFS of H-fuzzy semitiopogenous spaces and continuous maps between them is topological and cotopological. Using ordinary operations, we characterize coreflective subcatgories and then show that each of Top, Prox, Qunif, and Unig is isomorphic with some coreflective subcategory of HFS. Moreover, we show that sa-HFS is closed under the formation of initial sources in a-HFS, whewe a is a symmetrical elementary operation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.491-492
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• 2006

The horizontal high energy rotor ball mill ($Simoloyer^{(R)}$) is used to break and activate dry solids. It is used for dry-milling and in the vertical mount for wet-milling in leaching processes. Technical electric arc furnace (EAF) dust with high contents of zinc oxide, zinc ferrite and magnetite is efficiently separated by ambient temperature leaching. The process shows promise for industrial application

• Journal of Wetlands Research
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• v.9 no.1
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• pp.123-131
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• 2007

Effect of nitrogen-load condition on hydrogen ($H_2$) production and bacterial community in a continuous anaerobic hydrogen fermentation were investigated. The slight $H_2$ production on extremely low nitrogen-load condition (C/N ratio: 180) at the start-up period. The highest $H_2$ production was obtained when the C/N ratio was 36, the $H_2$ production yield ($mol-H_2/mol-glucose$) reached to 1.7, and it was indicated that Clostridium pasteurianum mainly contributed to the $H_2$ production. The $H_2$ production was decreased on both the lower (C/N: 72) and higher (C/N: 18) nitrogen-load conditions. The excess nitrogen-load was not always suitable for the hydrogen production. The fluctuation of $H_2$ production seemed to be caused by a change in the bacterial community according to the nitrogen-load condition, while a recovery of $H_2$ productivity was possible by a control of nitrogen-load condition through the bacterial community change. When the nitrogen-load condition was not suitable for hydrogen production, the lactic acid concentration was increased and also lactic acid bacteria were definitely detected, which suggested that the competition between hydrogen fermentator and lactic acid producer was occurred. These results demonstrated that the nitrogen-load condition affect on the $H_2$ productivity through the change of bacterial community in anaerobic hydrogen fermentation.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.