• Journal of Korean Society for Atmospheric Environment
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• v.10 no.4
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• pp.260-280
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• 1994

The STEM II(Sulfur Transport Eulerian Model II) was adapted to simulate transport/ chemistry/deposition of air Pollutants in the Eastern China and Korea. A 32 hour model simulation starting from 9 A.M. of 1989 November 25 during which no preciptation was observed. The Prevailing wind direction is from west to east. The MM4(Meteorological Model Version 4) was used to generate meteorological data such as temperatures, horizontal wind velocities and directions, humidities, air densities. Eddy diffusivities, dry deposition velocities and vertical wind velocities were calculated from the meteorological data. The initial condition and the emission data base were constructed from the measurements and governmental reports respectively. The model predictions of NO, NO$_2$, SO$_2$, $O_3$ at Seoul, Inchon and Pusan agree reasonably well with measurements. The model's predictability for the primary air pollutants is improved considerably as the time passes. Thus, it is concluded that the model's predictability can be significantly enhanced by reducing the uncertainties of initial conditions.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.266-269
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• 2020

In this study, we investigated the effect of a sulfur passivation (S-passivation) process step on the electrical properties of surface-channel In_0.7Ga_0.3As quantum-well (QW) metal-oxide-semiconductor field-effect transistors (MOSFETs) with S/D regrowth contacts. We fabricated long-channel In_0.7Ga_0.3As QW MOSFETs with and without (NH₄)₂S treatment and then deposited 1/4 nm of Al₂O₃/HfO₂ through atomic layer deposition. The devices with S-passivation exhibited lower values of subthreshold swing (74 mV/decade) and drain-induced barrier lowering (19 mV/V) than the devices without S-passivation. A conductance method was applied, and a low value of interface trap density D_it (2.83×10¹² cm^-2eV^-1) was obtained for the devices with S-passivation. Based on these results, interface traps between InGaAs and high-κ are other defect sources that need to be considered in future studies to improve III-V microsensor sensing platforms.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.2
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• pp.129-143
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• 2024

Sulfur dioxide (SO₂), a novel endogenous gas signaling molecule, is involved in the regulation of cardiac function. Exerting a key role in progression of hyperthyroidism-induced cardiomyopathy (HTC), myocardial fibrosis is mainly caused by myocardial apoptosis, leading to poor treatment outcomes and prognoses. This study aimed to investigate the effect of SO₂ on the hyperthyroidism-induced myocardial fibrosis and the underlying regulatory mechanisms. Elisa, Masson staining, Western-Blot, transmission electron microscope, and immunofluorescence were employed to evaluate the myocardial interstitial collagen deposition, endoplasmic reticulum stress (ERS), apoptosis, changes in endogenous SO₂, and Hippo pathways from in vitro and in vivo experiments. The study results indicated that the hyperthyroidism-induced myocardial fibrosis was accompanied by decreased cardiac function, and down-regulated ERS, apoptosis, and endogenous SO₂-producing enzyme aspartate aminotransferase (AAT)1/2 in cardiac myocytes. In contrast, exogenous SO₂ donors improved cardiac function, reduced myocardial interstitial collagen deposition, up-regulated AAT1/2, antagonized ERS and apoptosis, and inhibited excessive activation of Hippo pathway in hyperthyroid rats. In conclusion, the results herein suggested that SO₂ inhibited the overactivation of the Hippo pathway, antagonized ERS and apoptosis, and alleviated myocardial fibrosis in hyperthyroid rats. Therefore, this study was expected to identify intervention targets and new strategies for prevention and treatment of HTC.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.187-192
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• 2023

The use of biomass is increasing as a response to the convention on climate change. In Korea, a method applied to replace fossil fuels is using wood chips in a cogeneration plant. To remove air pollutants generated by burning wood chips, a selective denitrification facility (Selective catalytic reduction, SCR) is installed downstream. However, problems such as ash deposition and descaling of the equipment surface have been reported. The cause is thought to be unreacted ammonia slip caused by ammonia ions injected into the reducing agent and metal corrosion caused by an acidic environment. Element analysis confirmed that ash contained alkali metals and sulfur that could cause catalyst poisoning, leading to an increase in the size of ash particle and deposition. Measurement of the size of ash deposited inside the facility confirmed that the size of ash deposited on the catalyst was approximately three times larger than the size of generally formed ash. Therefore, it was concluded that a reduction in pore area of the catalyst by ash deposition on the surface of the catalyst could lead to a problem of increasing differential pressure in a denitrification facility.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.46-51
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• 2023

We investigated the MoS₂ thin film layer by thermolytic deposition and applied it to the silicon solar cells. MoS₂ thin films were made by two methods of dipping and spin coating of (NH₄)₂MoS₄ precursor solution. We implemented two types of substrates of microtextured and nano-microtextured 6-in. Si pn junction wafers. The fabricated MoS₂ thin film layer was analyzed, and solar cells were fabricated by applying the standard silicon solar cell process. The MoS₂ thin film layer of sulfur-deficient form was deposited on the n-type emitter layer, and electrons, which are minority carriers, were well transported at the interface and exhibited photovoltaic solar cell characteristics. The cell efficiencies were achieved at 5% for microtextured wafers and 2.56% for nano-microtextured wafers.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.98-104
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• 1997

Soil pollution intensity at Mt. Namsan in Seoul city which was expected to show significant soil contamination due to long-term air pollution was evaluated by comparing soil chemical properties at Mt. Kyebangsan in Hongcheon area as a control, and the bacteria participating in nitrogen or sulfur mineralization were assayed simultaneously in order to evaluate the validity of N and/or S mineralization bacteria as an index of soil contamination. The soil of Mt. Namsan showed 10 times higher concentration of hydrogen ion compared to that of Mt. Kyebangsan, which indicated that the soil had relatively been acidified seriously. Especially, large amount of canons were thought to be leached out from the soil, while the amount of extractable Al was getting larger and larger, which result in serious problems in soil ecosystem of the mountain. I could infer from soil chemical properties of the four study sites that the major reason of soil acidification was SOx deposition. However, the sulfur-reducing bacteria were not significantly different between the two regions, which indicated that the microbial dynamics of the soil ecosystem was not controlled by simple factor, but by multiple factors. By the way, the dynamics of bacteria participating in denitrification process was different between the two regions, which was more active at Mt. Kyebangsan than at Mt. Namsan. Thus, the microbial assay for nitrogen mineralization is desirable to be examined as a tool for evaluating soil health or microbial activity in soil ecosystem.

• Economic and Environmental Geology
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• v.23 no.2
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• pp.183-199
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• 1990

Ore deposits of Dongwon mine are composed of numerous gold and silver veins emplaced in sedimentary rocks of Cambrian Choseon Supergroup and granitoids of Cretaceous age. Ore veins of the mine can be divided into gold and silver veins on the base of vein structure, mineral assemblage and vein trends. Mutual relationships between gold and silver veins are uncertain. Gold veins are simple veins which are composed of base-metal sulfides, and electrum with quartz and ankerite. On the other hand, silver veins are complex veins which reveal three distinct stages of mineral deposition based on vein structure; stage I, deposition of small amounts of oxides and pyrite with quartz; stage II, deposition of base-metal sulfides, small amounts of Ag-bearing minerals, calcite and quartz; stage III, deposition of base metal sulfides, electrum, Ag-sulfosalts, native silver, carbonates and quartz. Homogenization temperature and salinity of fluid inclusion from quartz of gold vein are as follows; $229^{\circ}$ to $283^{\circ}C$, 4.7 to 6.4 wt.% equivalent NaCI. The ore mineralogy suggests that temperature(T) and sulfur fugacity($fs_2$) of the formation of the gold vein and stage III of silver vein are estimated as T ; $294^{\circ}$ to $318^{\circ}C$, $fs_2\;10^{-9.4}$ to $10^{-10.1}$ atm. and T; $240^{\circ}$ to $279^{\circ}C$, $fs_2;10^{-11.1}$ to $10^{-17.3}$ atm. respectively. Pressure condition during gold vein formation estimated from data of ore mineralogy and fluid inclusion range 500 to 750 bar.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1436-1438
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• 1997

In this paper, CdS thin films, which were widely used window layer of the CdS/CdTe and the CdS/$CuInSe_2$ heterojunction solar cell, were grown by chemical bath deposition, and The properties were investigated in detail. Cadmium acetate and thiourea were used as cadmium and sulfur source, respectively. And Ammonium acetate was used as the buffer solution. Also Ammonia was used for controlling pH concentration. The reaction velocity was increased with increasing reaction temperature and decreasing pH concentration. The crystal structure of CdS films grown with various pH concentration had the hexagonal structure with (002) plane peak. In the range of pH $9{\sim}9.5$, the intensity of the peak was highest, and as increasing pH concentration, decreased the intensity of the peak except pH12.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.611-619
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• 2010

The paper deals with the proper design of GGH(gas-gas heater) panel elements of desulfurization equipments in a thermoelectric power plant. When fossil fuels such as coal, petroleum et cetera are burnt to ashes, sulfur oxide compounds are produced, and calcareous sludges are deposited at GGH panel elements. In this case, operation of a power plant equipments is interrupted, and a tremendous economic loss comes into existence. One of the purposes of the paper is to find flow velocity distributions and regions of depositions when calcareous sludges pile up on the GGH panel elements through the fluid analysis. In the fluid analysis, flow velocity and position distributions of particles between GGH panel elements are demonstrated according to time variation for ammonia and calcium hydroxide particles.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.505-517
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• 1997

Lead and zinc mineralization of the Kwangsin mine was formed in quartz and carbonate veins that filled fault-related fractures in the limestone-rich Samtaesan Formation of the Chosun Supergroup and the phyllite-rich Suchangni Formation of unknown age. A K-Ar date of alteration sericite indicates that the Pb-Zn mineralization took place during Late Cretaceous (83.5 Ma), genetically in relation to the cooling of the nearby Muamsa Granite (83~87 Ma). Mineral paragenesis can be divided into three stages (I, II, III): (I) the deposition of barren massive white quartz, (II) the main Pb-Zn mineralization with deposition of white crystalline quartz and/or carbonates (rhodochrosite and dolomite), and (III) the deposition of post-ore barren calcite. Mineralogic and fluid inclusion data indicate that lead-zinc minerals in middle stage II (IIb) were deposited at temperatures between $182^{\circ}$ and $276^{\circ}C$ from fluids with salinities of 2.7 to 5.4 wt. % equiv. NaCl and with log $fs_2$ values of -15.5 to -11.8 atm. The relationship between homogenization temperature and salinity data indicates that lead-zinc deposition was a result of fluid boiling and later meteoric water mixing. Ore mineralization occurred at depths of about 600 to 700 m. Sulfur isotope compositions of sulfide minerals (${\delta}^{34}S_{CDT}=9.0{\sim}14.5$ ‰) indicate a relatively high ${\delta}^{34}S_{{\Sigma}S}$ value of ore fluids (up to 14 ‰), likely indicating an igneous source of sulfur largely mixed with an isotopically heavier sulfur source (possibly sulfates in surrounding sedimentary rocks). There is a remarkable decrease of calculated ${\delta}^{18}O$ value of water in hydrothermal fluids with increasing paragenetic time: stage I, 14.6~10.1 ‰; stage IIa, 5.8~2.2 ‰; stage IIb, 0.8~2.0 ‰; stage IIc, -6.1~-6.8 ‰, This indicates a progressive increase of meteoric water influx in the hydrothermal system at Kwangsin. Measured and calculated hydrogen and oxygen isotope values indicate that the Kwangsin hydrothermal fluids was formed from a circulating (due to intrusion of the Muamsa Granite) meteoric waters which evolved through interaction mainly with the Samtaesan Formation (${\delta}^{18}O=20.1$ to 24.9 ‰) under low water/rock ratios.