• Korean Journal of Microbiology
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• v.50 no.3
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• pp.254-260
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• 2014

Sulfur compound includes major electron acceptors for anaerobic respiration. In this study, cultivation-based study on sulfate- and sulfur-reducing bacteria of various wetlands of Korea was attempted. To isolate sulfate- and sulfur-reducing bacteria, anaerobic roll tube method was used to obtain typical black colonies of sulfate- and sulfur-reducing bacteria. Total 11 strains obtained were tentatively identified based on comparative 16S rDNA similarity and physiological property analysis. All sulfate-reducing bacteria (8 strains) belonged to genus Desulfovibrio with >99% 16S rDNA similarities. Three sulfur reducing bacteria were also isolated: two and one isolates were affiliated with Sulfurospirillum and Desulfitobacterium, respectively. These sulfate- and sulfur-reducing bacteria were able to utilize lactate and pyruvate and sulfite and thiosulfate as common electron donors and electron acceptors, respectively. This case study will provide fundamental information for obtaining useful indigenous sulfate- and sulfur-reducing bacteria from Korean wetlands employing various combinations of cultivation conditions.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.110-115
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• 2010

The plasticized polymer electrolytes based on polyvinylidene fluoride-co-hexafluoropropylene (P(VdF-co-HFP)), tetra (ethylene glycol) dimethyl ether (TEGDME), and lithium perchlorate ($LiClO_4$) are prepared for the lithium sulfur batteries by solution casting with a doctor-blade. The polymer electrolyte with EO : Li ratio of 16 : 1 shows the maximum ionic conductivity, $6.5\;{\times}\;10^{-4}\;S/cm$ at room temperature. To understand the effect of the salt concentration on the electrochemical performance, the polymer electrolytes are characterized using electrochemical impedance spectroscopy (EIS), infrared spectroscopy (IR), viscometer, and differential scanning calorimeter (DSC). The optimum concentration and mobility of the charge carriers could lead to enhance the utilization of sulfur active materials and the cyclability of the Li/S unit cell.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.225-230
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• 2013

A new heteropolyanion-based ionic ($[Hmim]_5PMo_{10}V_2O_{40}$) was synthesized by the reaction of molybdovanadophosphoric acid ($H_5PMo_{10}O_{40}$) with N-methylimidazole. [$[Hmim]_5PMo_{10}V_2O_{40}$ showed a high catalytic activity in the oxidative desulfurization of sulfur-containing compounds in 1-methylimidazolium tetrafluoroborate ($[Hmim]BF_4$) ionic liquid using 30% aqueous $H_2O_2$ as the oxidant. The catalytic system was of high activity, simplified workup and flexible recyclability. The catalytic oxidation reactivity of sulfur-containing compounds decreased in the order dibenzothiophene (DBT) > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT). The influences of various parameters including reaction time (t) and temperature (T), catalyst dosage, and oxidant to sulfur molar ratio n(O)/n(S) on the desulfurization of model oil were investigated in details. 99.1% of DBT conversion in the model oil was achieved at atmospheric pressure under the optimal conditions: n(O)/n(S) = 4:1, $60^{\circ}C$, 100 min and molar ratio of catalyst to sulfur of 0.062. The ionic liquid can be recycled six times without significant decrease in activity.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.162-163
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• 2005

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1697-1699
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• 1996

EPDM compound can be cured with either the sulfur and peroxide based systems. In this study, heat resistance and weatherability of EPDM compounds depending on curing systems were investigated. The test results showed that the peroxide-cured EPDM was more resistant to heat ageing and UV photo-degradation than the sulfur-cured EPDM and it is due to C-C bond is more stable than C-S, S-S bond.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.31-36
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• 2008

In hydrogen production for fuel cell by reforming ADG, sulfur compounds, odorant in ADG, are detrimental to reforming catalyst and fuel cell electrodes. We prepared alkali metal impregnated activated carbon to remove sulfur compounds in ADG by adsorption. The sulfur breakthrough adsorption capacity was changed depending on the oxygen concentration and relative humidity. Oxygen 0.2 vol% and RH 90% showed the highest sulfur breakthrough capacity. Adsorption characteristics of $H_2S$ on KI impregnated activated carbon were evaluated using dynamic adsorption method in a fixed bed. Based on the results, adsorption tower was designed and field-tested.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1275-1284
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• 2009

A directly heated $SO_3$ decomposer for the sulfur-iodine and hybrid-sulfur processes has been introduced and analyzed using the computational fluid dynamics (CFD) code CFX 11. The use of a directly heated decomposition reactor in conjunction with a very high temperature reactor (VHTR) allows for higher decomposition reactor operating temperatures. However, the high temperatures and strongly corrosive operating conditions associated with $SO_3$ decomposition present challenges for the structural materials of decomposition reactors. In order to resolve these problems, we have designed a directly heated $SO_3$ decomposer using RA330 alloy as a structural material and have performed a CFD analysis of the design based on the finite rate chemistry model. The CFD results show the maximum temperature of the structural material could be maintained sufficiently below 1073 K, which is considered the target temperature for RA 330. The CFD simulations also indicated good performance in terms of $SO_3$ decomposition for the design parameters of the present study.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.1
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• pp.1-8
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• 2023

The major concern in the deep geological disposal of spent nuclear fuels include sulfide-induced corrosion and stress corrosion cracking of copper canisters. Sulfur diffusion into copper canisters may induce copper embrittlement by causing Cu₂S particle formation along grain boundaries; these sulfide particles can act as crack initiation sites and eventually cause embrittlement. To prevent the formation of Cu₂S along grain boundaries and sulfur-induced copper embrittlement, copper alloys are designed in this study. Alloying elements that can act as chemical anchors to suppress sulfur diffusion and the formation of Cu₂S along grain boundaries are investigated based on the understanding of the microscopic mechanism of sulfur diffusion and Cu₂S precipitation along grain boundaries. Copper alloy ingots are experimentally manufactured to validate the alloying elements. Microstructural analysis using scanning electron microscopy with energy dispersive spectroscopy demonstrates that Cu₂S particles are not formed at grain boundaries but randomly distributed within grains in all the vacuum arc-melted Cu alloys (Cu-Si, Cu-Ag, and Cu-Zr). Further studies will be conducted to evaluate the mechanical and corrosion properties of the developed Cu alloys.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.55-62
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• 2021

This study aims to reduce the rancid odor generated during the fermentation process of kimchi by inserting zinc oxide (ZnO) into an inorganic porous material with a high surface area to decompose or adsorb the fermentation odor. ZnO activated by the presence of moisture exhibits decomposition of rancid odors. Mixed with Titanium dioxide (TiO₂), a photocatalyst. To manufacture the packaging liner used in this study, NaOH, ZnCl₂, and TiO₂ powder were placed in a tank with diatomite and water. The sludge obtained via a hydrothermal ultrasonication synthesis was sintered in an oven. After being pin-milled and melt-blended, the powders were mixed with linear low-density polyethylene (L-LDPE) to make a masterbatch (M/B), which was further used to manufacture liners. A gas detector (GasTiger 2000) was used to investigate the total amount of sulfur compounds during fermentation and determine the reduction rate of the odor-causing compounds. The packaging liner cross-section and surface were investigated using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) to observe the adsorption of sulfur compounds. A variety of sulfur compounds associated with the perceived unpleasant odor of kimchi were analyzed using gas chromatography-mass spectrometry (GC-MS). For the analyses, kimchi was homogenized at room temperature and divided into several sample dishes. The performance of the liner was evaluated by comparing the total area of the GC-MS signals of major off-flavor sulfur compounds during the five days of fermentation at 20℃. As a result, Nano-grade inorganic compound liners reduced the sulfur content by 67 % on average, compared to ordinary polyethylene (PE) foam liners. Afterwards SEM-EDS was used to analyze the sulfur content adsorbed by the liners. The findings of this study strongly suggest that decomposition and adsorption of the odor-generating compounds occur more effectively in the newly-developed inorganic nanocomposite liners.

• The Korea Journal of Herbology
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• v.27 no.6
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• pp.43-48
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• 2012

Objectives : This study was investigated to determine the contents of pesticide residues and sulfur dioxide residues in commercial herbal medicines in Korea. Methods : Chromatographic test was performed on 100 samples consisted with 10 kinds of medicinal plants including improted and domestic products. To establish 19 pesticide residues (DDE, DDD, DDT, Dieldrin, Methoxychlor, BHC isomers, Aldrin, Endosulfan isomers, Endrin, Captan, Procymidone, Chlorpyrifos and Imidacloprid) in commercial herbal medicines, chromatographic equipments were used with the gas chromatography-mass detector and gas chromatography-electron capture detector for qualitative analysis. The imidacloprid analysis was performed by high performance liquid chromatograpgy-ultraviolet detector at 270 nm UV wavelength. The contents of sulfur dioxides were analyzed by modified Monnier-Williams method. All methods were based on notification procedure of Korea Food & Drug Administration (KFDA). Results : The residual pesticides were not founded in improted and domestic samples. Among 100 samples, the residues of sulfur dioxide in 73 samples were not detected and 25 samples showed contents in the range of 0~21.90 mg/kg. The excess samples of MRLs were 2 samples (30 mg/kg to medicinal herbs), Asiasari Radix et Rhizoma (Imported product) and the average amount of sulfur dioxide in 2 unsuitable samples were 14.83 mg/kg. These samples were found to transgress KFDA regulatory guidance of residual sulfur dioxide. Conclusion : These results are able to use as basic data to improve the reliability and value of commercial medicinal herbs.