• Economic and Environmental Geology
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• v.24 no.2
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• pp.107-129
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• 1991

The Yonghwa gold-silver deposits are emplaced along $N15^{\circ}{\sim}25^{\circ}W$ trending fissures in middle Cretaceous porphyritic granite or Precambrian Sobaegsan gneiss complex. The results of paragenetic studies suggest that vein filling can be subdivided into four identifiable stages; state I: the main sulfide stage, characterized by base-metal sulfide minerals, iron oxides and minor electrum, stage II: electrum stage, stage III: electrum and silver-bearing sulfosalts stage, stage IV: post ore stage of carbonates and quartz. The ore mineralogy suggests that depositional temperature of the formation of the gold and silver minerals are estimated as 200 to $250^{\circ}C$ and 140 to $180^{\circ}C$, respectively. Sulfur fugacity of the formation of the gold and silver minerals are estimated as $10^{-14.0}$ to $10^{-12.2}$ atm and $10^{-18.5}$ to $10^{-17.2}$ atm, respectively. A consideration of the pressure regime during ore deposition bases on the fluid inclusion evidence of boiling suggests lithostatic pressure of less than 180 bars. This range of pressure indicate that vein system lay at depth of 700m below the surface at the time during mineralization. Salinities of ore-bearing fluids range from 0.4 to 6.9 wt.% equivalent NaCl. The sulfur and carbon isotopic data reveal that these elements were probably derived from a deep-seated source. The ${\delta}^{18}O$ of the hydrothermal fluid was determined from ${\delta}^{18}O$ values of quartz and calcite. Oxygen and hydrogen isotopic studies reveal that meteoric water dominate over ore-bearing fluid.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.398-402
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• 2012

The catalytic performance of some metal oxides in the vapor phase selective oxidation of $H_2S$ in the stream containing ammonia and water was investigated. Among the catalysts tested $Fe_2O_3/SiO_2$ was the most promising catalyst for practical application. It showed higher than 90% $H_2S$ conversion and very small amount of $SO_2$ emission over a temperature range of $240{\sim}280^{\circ}C$. The effects of reaction temperature, $O_2/H_2S$ ratio, amount of ammonia and water vapor on the catalytic activity of $Fe_2O_3/SiO_2$ were discussed to better understand the reaction mechanism. The $H_2S$ conversion showed a maximum at $260^{\circ}C$ and it decreased with increasing temperature over $280^{\circ}C$. With an increase of $O_2/H_2S$ ratio from 0.5 to 4, the conversion was slightly increased, but the selectivity to elemental sulfur was remarkably decreased. The increase of ammonia amount favored the conversion and the selectivity to elemental sulfur with a decrease in $SO_2$ production. The presence of water vapor decreased both the activity and the selectivity to sulfur, but increased the ATS selectivity.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.4
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• pp.15-22
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• 2020

The landfill gas produced in landfill is generally made up of methane(CH4) and carbon dioxide(CO2) of more than 90%, with the remainder made up of hydrogen sulfide(H2S). However, separate pre-treatment facilities are essential as hydrogen sulfide contained in landfill gas is combined with oxygen during the combustion process to generate sulfur oxides and acid rain combined with moisture in the atmosphere. Various desulfurization technologies have been used in Korea to desulfurize landfill gas. Although general desulfurization processes apply various physical and chemical methods, such as treatment of sediment generation according to the CaCO3 generation reaction and treatment through adsorbent, there is a problem of secondary wastes such as wastewater. As a way to solve this problem, a biological treatment process is used to generate and treat it with sludge-type sulfide (S°) using a biological treatment process.In this study, as a basic study of technology for utilizing the biological treatment by-products of hydrogen sulfide in landfill gas, an experiment was conducted to use the by-product as a mixture of concrete. According to the analysis of the mixture concrete strength of sulfur products, the mixture of sulfur by-products affects the strength of concrete and shows the highest strength value when mixing 10%.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.7
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• pp.1030-1035
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• 2008

Recently, the International Maritime Organization makes an effort for an effective solution against the emissions from shipping in the international maritime industry. The objective of the study was to quantify the exhaust emissions of marine heavy fuel oil in the combustion process of the spray flame. An experiment was performed to measure CO, $CO_2$, NOx, $SO_2$, ${N_2}O$, DS, SOF and the other components with the flame temperature. The sampling probe was directly set up in the flame fields at each position of 103, 324, 545, 766 and 987mm vertically apart from the fuel-injected nozzle in the burner furnace. From the results of the study, it was estimated that approximately 270ppm of oxides of nitrogen (NOx), $1000{\sim}1400ppm$ of sulfur dioxide ($SO_2$), 8ppm of nitrous oxide (${N_2}O$), $2.0{\sim}2.5g/m^3$ of particulate matter (PM) divided with dry soot (DS) and soluble organic fraction (SOF) and $60{\sim}80mg/m^3$ of sulfuric acid. With respect to further development of this work, the emission quantification could also be applied to assessing emission reduction from the international shipping.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.443-446
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• 2014

Recently the demand for natural gas as clean and safe energy due to concerns about global warming and interests in green ship is increasing. The dual fuel(DF) engine, one of environmentally friendly engines, is preferred for general merchant ships and power plants as well as LNG carriers. This is for the reasons of having higher efficiency and lower nitrogen and sulfur oxides emissions by operating on LNG fuel with a small amount of light fuel oil. In this study, the engine body vibration characteristics of 12V50DF in a generator set with engine-resilient-mounted, generator-rigid-mounted and flexible-coupling configuration are investigated through theoretical analysis and comprehensive vibration measurement. This analysis showed the dynamic behavior of engine excitation forces and seismic waves. And the suitable countermeasures for reducing vibration and safe operation are proposed.

• Economic and Environmental Geology
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• v.28 no.2
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• pp.93-108
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• 1995

The Bobae sericite deposit occurs in rhyodacite of the Cretaceous volcanogenic sedimentary rocks, Upper Yucheon Group, in the western part of Pusan. The alteration zones are divided into the phyllie and prophylitic zone based on the mineral assemblages. The phyllic zone is subdivided into three subzones; Andalusite-Pyrophyllite, Sericite and Albite subzones. Oxides vs. $Al_2O_3$ contents show variations corresponding to mineral assemblage in each alteration zone. On the basis of bulk chemical compositions, it was found that $SiO_2$ increases in the Andalusite-Pyrophyllite subzone and $K_2O$ in the Sericite subzone. The oxygen, hydrogen and sulfur isotope analysis indicates that the fluids were originally derived from the residual magmatic solution. It has been mixed with abundant meteoric water later. The ore-forming temperatures obtained from sericite (illite) geothermometer are about $250{\sim}350^{\circ}C$. Considering the phase stability relation, PoT conditions of the andalusite-pyrophyllite subzone were estimated to be less than 0.5 kb and almost $400^{\circ}C$, respectively. The K-Ar ages of sericites indicate that the clay deposit is genetically related to the Cretaceous-Paleogene Masan Hornblende-Biotite Granite.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.372-376
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• 2015

The experiment was performed using the cleaning precipitator To investigate the absorption efficiency of the $SO_X/NO_X$ of the aqueous ammonia solution. Concentration of the cleaning liquid is 0.1, 0.5, and 1.0% with increasing absorption efficiency has improved. However, the reaction shown only a difference in time. Absorption efficiency has improved in accordance with the gas residence time. When the direction of the same gas and the cleaning liquid is determined that there is the effect of increasing the residence time. The relative impact of $SO_X$ and $NO_X$ is this likely to react slower than $SO_X/NO_X$. The yield is determined to require adjustment of the cleaning dust collector according to the concentration of the next gas.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.1
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• pp.91-99
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• 1996

Ozone, sulfur dioxide, and nitrogen oxides were measured at Kosan, Cheju Island, Korea during the period of March 11 .sim. April 19, 1994. During the measurement period, the average SO$_{2}$ and NOx concentrations were about 0.97 ppb and 3.5 ppb, respectively. Average NO concentration was below the detection limit and thus the effect of NO during the period was negligible. The concentrations of SO$_{2}$ and Nox were lower than those at other urban area in Korea but higher than other remote areas in the world. Average $O_{3}$ concentration for the period was about 55 ppb, slightly higher than or comparable to those at remote marine areas in the world. Detailed analyses of trend of gaseous species concentrations show that the effects of local NO emission sources for NOx concentration were significant during the period, while those of local SO$_{2}$ emission sources were not high. Backward trajectory analysis results show that when SO$_{2}$ or $O_{3}$ concentration was higher than the average concentrations, the air parcels were transported from China.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.266-268
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• 2009

In this paper, authors deal with a power conditioning system (PCS) of high efficiency for a proton exchange membrane fuel cell (PEMFC) generation system. Fuel cells are a direct current (DC) power generators. They generate electricity through an electrochemical process that converts the energy stored in a fuel directly into electricity. Fuel cells have many benefits, which produce no particulate matter, nitrogen or sulfur oxides. And they have few moving parts and produce little or no noise. When fueled by hydrogen, they yield only heat and water as byproducts. Their wide application can reduce our dependence on fossil fuels and foreign sources of petroleum. This paper studies on a novel PCS circuit topology of high efficiency using in PEMFC generation system The controlling switches in the PCS is operated to soft switching. Some digital simulation results and experimental results for the proposed PCS is confirmed to the validity of the analytical results.

• Journal of the Korean institute of surface engineering
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• v.45 no.2
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• pp.61-69
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• 2012

Alloys of Fe-(5, 10, 15)Al and Fe-(10, 20, 30, 40)Cr were corroded at 700 and $800^{\circ}C$ for 70 hr in either atmospheric air or 1 atm of Ar+$1%SO_2$ gases. In these atmospheres, Fe-5Al and Fe-10Cr alloys displayed poor corrosion resistance. In atmospheric air, Fe-5Al alloys formed oxide nodules, while Fe-10Cr alloys formed thick scales and internal oxides. In Ar+$1%SO_2$ gases, Fe-5Al and Fe-10Cr alloys formed thick, nonadherent bi-layered scales, which grew primarily by the outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions. By contrast, in atmospheric air and Ar+$1%SO_2$ gases, Fe-(10, 15)Al and Fe-(20, 30, 40)Cr alloys displayed good corrosion resistance by forming $Al_2O_3$ and $Cr_2O_3$ layers on the surface, respectively.