• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.179-185
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• 2005

Polycyclic aromatic hydrocarbons (PAHs) are a kind of toxic environmental pollutants and has been accumulated usually in marine sediments. Due to their potential hazardous to human, removal of PAHs from environments has been great concern. In the present study, the effect of microbial inoculation and the supplementation of mixed form cyclodextrin (M-CD) was assessed in the pre-sterilized or nonsterilized microcosms for optimizing operational conditions for ex situ bioremediation of sediments contaminated by PAHs. Activity of electron transport system (ETSA) was increased by the addition of M-CD regardless of inoculation of microorganisms in microcosms without sterilization. The degradation rate of PAHs in sterilized microcosms was app. 9-20% by the inoculation of single strain and 24-37% by the inoculation of microbial consortium supplemented with 1% M-CD, respectively. The degradation was not observed in microcosms without sterilization under the same conditions. The proportion of inoculated microorganisms also decreased in nonsterilized microcosms. Signals of inoculated bacteria were decreased to detection limit after 2 days in the microcosms without M-CD. In conclusion, microbial inoculation with appropriate carbon sources and removal of natural flora and grazers are required for the efficient ex situ bioremediation of sediments contaminated by PAHs in bioslurry reactor.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.188-189
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• 2014

코스트 저감과 연비 향상을 위한 부품 중 반복 하중과 내열성 부품의 적용이 증대하고 있다. 기존의 자동차 부품에서는 펄라이트가 석출되기 때문에 고탄소 철계 부품에 팩크로마이징 공정을 이용한 크롬탄화물을 형성하면서 탄화수소계 가스를 투입하므로서 기존의 불활성 분위기를 깨고 비평형상태로 분위기를 유지함으로 높은 경도의 $(Cr,Fe)_{23}C_6$와 $(Cr,Fe)_7C_3$ 복합 탄화물의 형성과 이에 의한 마찰계수 변화를 관찰하였다.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.1
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• pp.12-22
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• 2004

In order to evaluate the potential of partial hydrocarbon substitution to improve the safety of hydrogen use in general and the performance of internal combustion engines in particular, the outward propagation and development of surface cellular instability of spark-ignited spherical premixed flames of mixtures of hydrogen, hydrocarbon, and air were experimentally studied at NTP (normal temperature and pressure) condition in a constant-pressure combustion chamber. With propane being the substituent, the laminar burning velocities, the Markstein lengths, and the propensity of cell formation were experimentally determined, while the laminar burning velocities and the associated flame thicknesses were computed using a recent kinetic mechanism. Results show substantial reduction of laminar burning velocities with propane substitution, and support the potential of propane as a suppressant of both diffusional-thermal and hydrodynamic cellular instabilities in hydrogen-air flames.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.85-96
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• 2000

The purpose of this study was to Investigate the effect of environmental conditions on the degradation of total petroleum hydrocarbons(TPH) in soil. The soil used for this study was sandy loam. Target contaminant, diesel oil, was spiked at 10.000mgTPH/kg dry soil. Moisture content was controlled to 50%, 70%, and 90% of field capacity of the soil. Temperature was controlled to $5^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$, and $30^{\circ}C$. The active degradation of TPH was observed at the moisture contents of 50% and 70% of field capacity, and temperature of $10^{\circ}C$ to $30^{\circ}C$. Degradation rate of n-alkanes was about two times greater than that of TPH. Volatilization loss of TPH was about 2% of initial concentration. Biocide control and no aeration experiments indicated that removal of TPH was primarily occurred by biodegradation under aerobic condition.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.37-44
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• 1995

A coprecipitation method was used for preparing Ca and Pt doped $SnO_{2}$-based material. Crystallite size and specific surface area were investigated by TEM, XRD and BET analysis. $SnO_{2}(Ca)/Pt$ based thick film devices were prepared by a screen printing technique for hydrocarbon gas detecting. Then the electrical and sensing characteristics of devices were investigated. As Ca and Pt addition, the crystal growth of $SnO_{2}$ was suppressed during calcining and sintering, and the sensitivity of $SnO_{2}(Ca)/Pt$ thick film to gas was enhanced. Also any difference in the sensing properties has to be attributed to the Pt and Au electrode. For the 2000 ppm $CH_{4}$, the sensitivity of $SnO_{2}(Ca)/Pt$ thick film devices were about 83% at an operating temperature of $400^{\circ}C$.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.397-403
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• 2023

In this study, the effect of the addition of fluorinated surfactant FS-606 on the solubilization of n-hexane by hydrocarbon surfactant CDP-W was investigated. Oil drop contacting experiments revealed that solubilization rate is independent of initial oil drop size and proportional to the initial surfactant concentration, suggesting that solubilization of n-hexane oil by the surfactant mixture of FS-606 and CDP-W is controlled by an interface-controlled mechanism. In addition, the solubilization rate has been shown to increase with an increase in FS-606 composition, reach a maximum, and then decrease with a further increase in FS-606 composition. On the other hand, the interfacial tension between micellar solution and n-hexane oil has been found to decrease with an increase in FS-606 composition, reach a minimum, and then increase with a further increase in FS-606 composition.

• Membrane Journal
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• v.33 no.6
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• pp.325-343
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• 2023

Direct methanol fuel cells (DMFCs) have been attracting attention as energy conversion devices that can directly supply methanol liquid fuel without a fuel reforming process. The commercial polymer electrolyte membranes (PEMs) currently applied to DMFC are perfluorosulfonic acid ionomer-based PEMs, which exhibit high proton conductivity and physicochemical stability during the operation. However, problems such as high methanol permeability and environmental pollutants generated during decomposition require the development of PEMs for DMFCs using novel ionomers. Recently, studies have been reported to develop PEMs using hydrocarbon-based ionomers that exhibit low fuel permeability and high physicochemical stability. This review introduces the following studies on hydrocarbon-based PEMs for DMFC applications: 1) synthesis of grafting copolymers that exhibit distinct hydrophilic/hydrophobic phase-separated structure to improve both proton conductivity and methanol selectivity, 2) introduction of cross-linked structure during PEM fabrication to reduce the methanol permeability and improve dimensional stability, and 3) incorporation of organic/inorganic composites or reinforcing substrates to develop reinforced composite membranes showing improved PEM performances and durability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.2
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• pp.179-188
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• 2011

Experiments were conducted in a constant-pressure combustion chamber to investigate the effects of hydrocarbon addition on cellular instabilities of syngas-air flames. The measured laminar burning velocities were compared with the predicted results computed using reliable kinetic mechanisms with detailed transport and chemistry. The cellular instabilities that included hydrodynamic and diffusional-thermal instabilities of the hydrocarbon-added syngas-air flames were identified and evaluated. Further, experimentally measured critical Peclet numbers for fuel-lean flames were compared with the predicted results. Experimental results showed that the laminar burning velocities decreased significantly with an increase in the amount of hydrocarbon added in the reactant mixtures. With addition of propane and butane, the propensity for cell formation was significantly diminished whereas the cellular instabilities for methane-added syngas-air flames were not suppressed.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.565-574
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• 2019

Fischer-Tropsch synthesis process is a typical method for synthesizing hydrocarbons from syngas and is mainly known as iron (Fe) and cobalt (Co) catalysts. Currently, some technologies such as CTL (Coal to Liquid) and GTL (Gas to Liquid) are operated on a commercial scale depending on the products, but the research to produce light hydrocarbons and middle distillates directly has not been commercialized. Therefore, in this study, domestic studies for direct production of light hydrocarbons and middle distillates are summarized and the effect of catalyst preparation, promoter addition, zeolite combination on product selectivity is investigated.

• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.45-53
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• 1998

The purpose of this study was to evaluate effects of initial concentration and nutrients in treatment of petroleum hydrocarbon contaminated soils. The reactor used in this study was slurry-phase bioreactor of in-vessel type. Performance results on treatment of diesel fuel contaminated soils and micorbial growth were generated at the bench-scale level. The fate of TPH(Total Petroleum Hydrocarbon) and the microbial growth were evaluated in combination with biodegradation rate. Effect of initial loading levels of 50,000 and 100,000mg TPH/kg soil was studied. Performance results with two reactors were showed at the total TPH removal rate of 90.5% and 90.8%, respectively. However, the reactor with the initial concentration of 50,000mg TPH/kg soil showed higher biological TPH removal efficiency except for removal by volatilization than the other Although the different amount of nutrients was applied in two reactors, there was no remarkable difference in microbial growth rate. However, considerable factor in this results was that applied different initial concentration to two reactors. Although initial concentration was two times higher than it applied to the reactor without addition of nutrients, in total and biological TPH removal rate the reactor with addition of nutrients showed a higher than the other.