• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.81-86
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• 2007

Hollow fiber membrane G-L contactors are widely used to remove $SO_2$ emitted from industrial facilities. In this work, the mathematical modeling and computer simulation for hollow membrane G-L contactors is carried out to analyze $SO_2$ absorption behavior in hollow fiber membranes. The model is solved with the finite element method using a commercial software. Investigated is the dependency of $SO_2$ removal efficiency and mass transfer characteristics on gas velocities, membrane mass transfer coefficients and physical properties of contactors. The membrane mass transfer coefficients are estimated by fitting the experimental data with the simulated $SO_2$ removal efficiencies. In addition, a design methodology of membrane contactors is suggested.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.689-694
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• 2006

The system performance of a bioactive foam reactor (BFR), that consists of a foam column using a surfactant and a biodegradation basin containing suspended bacteria, was investigated for the treatment of gaseous toluene or a mixture of four volatile organic compounds (VOCs, benzene, toluene, p-xylene, and styrene). Overall, the BFR achieved stable VOC removal efficiencies, indicating that it can be used as a potential alternative over conventional packed-bed biofilters. Furthermore, a dynamic loading test showed that relatively constant removal was maintained at the elevated loading due to a high mass transfer rate in the foam column. However, as the inlet concentration of VOCs increased, a portion of the VOCs mass-transferred to the liquid phase was stripped out from the biodegradation basin, resulting in a decrease in the overall removal efficiency. In the BFR, the removal efficiency of the individual VOC was mainly determined depending on the biodegradation rate (styrene > toluene > benzene > p-xylene), rather than the mass transfer rate. Consequently, increases in the microbial activity and the volume of the basin could improve the overall performance of the BFR system. Further investigation on microbial activity and community dynamics is required for the BFR when subjected to high loadings of VOC mixtures.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.603-610
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• 2009

This research was performed to improve removal efficiency of toluene and methyl ethyl ketone (MEK) using Candida tropicalis, one of the yeast species. An airlift loop bioreactor (ALB) was employed to enhance the capability of mass transfer for toluene and MEK from the gas phase to the liquid, microbial phase. Polymer gel media made from PAC, alginate and PEG was applied for the effective immobilization of the yeast strain on the polymer gel media. The experimental results indicated that the mass transfer coefficient of toluene without polymer gel media was 1.29 $min^{-1}$ at a gas retention time of 15 sec, whereas the KLa value for toluene was increased to 4.07 $min^{-1}$ by adding the media, confirming the enhanced mass transfer of volatile organic compounds between the gas and liquid phases. The removal efficiency of toluene and MEK by using yeast-immobilized polymer gel media in the ALB was greater than 80% at different pollutant loading rates (5, 10, 19 and 37 g/$m^3$/hr for toluene, 4.5, 8.9, 17.8 and 35.1 g/$m^3$/hr for MEK). In addition, an elimination capacity test conducted by changing inlet loading rates stepwise demonstrated that maximum elimination capacities for toluene and MEK were 70.4 and 56.4 g/$m^3$/hr, respectively.

• Membrane Journal
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• v.26 no.4
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• pp.239-252
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• 2016

Two-dimensional materials offer unique characteristics for membrane applications to water technology. With its atomic thickness, availability and stackability, graphene in particular is attracting attention in the research and industrial communities. Here, we present a brief overview of the recent research activities in this rising topic with bringing two membrane architecture into focus. Pristine graphene in single- and polycrystallinity poses a unique diffusion barrier property for most of chemical species at broad ambient conditions. If well designed and controlled, physical and chemical perforation can turn this barrier layer to a thinnest feasible membrane that permits ultimate permeation at given pore sizes. For subcontinuum pores, both molecular dynamics simulations and experiments predict potential salt rejection to envisage a seawater desalination application. Another novel membrane architecture is a stack of individual layers of 2D materials. When graphene-based platelets are chemically modified and stacked, the interplanar spacing forms a narrow transport pathway capable of separation of solvated ions from pure water. Bearing unbeknownst permeance and selectivity, both membrane architecture - ultrathin porous graphene and stacked platelets - offer a promising prospect for new extraordinary membranes for water technology applications.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.83-89
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• 2022

Since the pandemic of COVID-19, active investigation to develop immunity to infectious disease by delivering nucleic acids has been proceeded. Particularly, many studies have been conducted on non-viral vector as several vital side-effects which were found on nucleic acid delivery system using viral vectors. In this study, we have developed plasmid DNA (pDNA) loaded-hyaluronic acid derivative (HA) coated-polyethyleneimine (PEI) based polyplex for enhanced nucleic acid delivery efficiency. We have optimized the ratio of pDNA : PEI : HA by measuring size and protein transcription efficiency. The final product, polyplex-HA, was characterized through measuring size, zeta-potential and TEM image. Intracellular uptake and protein transcription efficiency were compared to commercially available transfection reagent, lipofectamine, through fluorescence image and flow cytometry. In conclusion, polyplex-HA presents a novel gene delivery system for efficient and stable protein transcription since it is available for delivering various genetic materials and has less immunoreactivity.

• Journal of Dairy Science and Biotechnology
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• v.35 no.3
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• pp.208-214
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• 2017

The aims of this study were to manufacture a hydrolyzed goat milk protein (HGMP)/chitosan ologisaccharide (CSO) nano-delivery system (NDS) and to investigate the effects of production variables, such as sodium tripolyphosphate (TPP), HGMP, and CSO concentration levels, on the formation and physicochemical properties of the NDS. An HGMP/CSO NDS was produced using the ionic gelation method at pH 5.5. Transmission electron microscopy and a particle size analyzer were used to determine the morphological and physicochemical properties of NDSs, respectively. The size of the HGMP/CSO NDS decreased from 225 to 138 nm as HGMP and CSO concentration levels decreased. The NDS had a positive surface charge, with a zeta-potential value of +23 mV. The encapsulation efficiency (EE) of docosahexaenoic acid was enhanced as the HGMP concentration level increased. Additionally, increasing the concentration level of CSO resulted in an increase in the EE of resveratrol. The HGMP/CSO NDS exhibited good physical stability during freeze-drying. Thus, our findings showed that the HGMP/CSO NDS was successfully manufactured and that HGMP and CSO concentration levels were key factors affecting the physicochemical properties of the NDS.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.640-646
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• 2011

Dissolved oxygen (DO) refers to the volume of oxygen that is contained in water, and is a major indicator of water quality. The objective of this paper was to investigate the effect of salinity on the dissolved oxygen characteristics in an ejector-aerator. An experimental aeration system composed of a motor-pump, an ejector, a motor-blower, a set of aeration and recirculation tank and a control panel. The dissolved oxygen concentrations decreased with the water salinity. The volumetric mass transfer coefficient increased with increasing the water salinity.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1436-1437
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• 2006

탄소 나노튜브는 기계적인 강도가 크고, 표면적이 넘으며 전기전도도가 우수할 뿐만 아니라 화학적으로도 안정하기 때문에 최근 여러분야에 적용하려는 연구가 활발히 진행되고 있는 나노물질이다. 특히 바이오센서에서 탄소 나노튜브는 작업 전극의 활성을 증대시키는 물질로써, 안정적인 효소 고정화에 기여하는 reservior로써 그리고 반응에서 생성된 전자를 전극에 효과적으로 전달하는 매개체로써 이용되고 있다. 본 연구에서는 다중벽 탄소 나노튜브(multi-walled carbon nanotube ; MWNT)를 화학처리하여 작용기를 유도한 후 효소와 반응시킨 용액으로 스크린 프린팅 방법으로 제작된 탄소전극의 표면을 개질하는 방법으로 바이오센서를 제작하였다. 이렇게 제작된 바이오센서를 탄소 나노튜브를 이용하지 않은 바이오 센서와 전기화학적으로 분석한 결과 감도가 약 3배정도 증가하는 결과를 얻을 수 있었다. 이것은 효소반응 시 발생된 전자가 나노튜브를 통해서 전극에 효과적으로 전달됨을 의미한다.

• Journal of Life Science
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• v.16 no.2 s.75
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• pp.315-322
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• 2006

FS11052, a novel microbial metabolite from Streptomyces spp. was identified as a small molecular substance and shown inhibition activities for the release of neurotransmitter from rat hippocampal neuron and PC12 cells. FS11052 is an inhibitor of tritiated norepinephrine ($[^3H]-NE$) release in high $K^+$ buffer solution containing ionomycin, indicating that FS11052 inhibits neurotransmitter release after the influx of $Ca^{2+}$ ions. When examined the effect of FS11052 on glucuronidase release from guinea pig neutrophils, FS11052 inhibited glucuronidase release: when treated with $5{\mu}g/ml$ of FS11052, which was not induced cellular cytotoxicity. The fact that the glucuronidase release in neutrophil and norepinephrine release in neuron was inhibited suggests the similarity in the locations and the mechanisms of FS11052 action targets. When treated with $5{\mu}g/ml$ of FS11052, $[^3H]-NE$ release and neurite extension for both rat hippocampal neurons and PC12 cells were prevented. These observations of FS11052 functioning as an inhibitor of neurotransmitter release suggest that FS11052 has an important role in synaptic transmission in neuron.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.77-81
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• 2012

In a cryogenic propellant tank the pressurant is contracted due to heat loss and the propellant itself evaporates. On a restartable propulsion system such phenomena are more intensive because the propellant contacts with the pressurant on the larger surface during the coast flight. Such heat and mass transfer phenomena should be considered for estimating the amount of pressurant. On the hypothesis that the heat and mass transfer quasi-equilibrium is achieved during the coast flight, the calculation process of the equilibrium pressure is presented. On the process the amount of loaded helium on the Falcon-1 second stage is calculated.