• 한국대기환경학회지
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• 제10권4호
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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.

• 센서학회지
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• 제29권4호
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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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• 제28권2호
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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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• 제22권3호
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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.

• 반도체디스플레이기술학회지
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• 제22권3호
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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.

• 한국산림과학회지
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• 제86권1호
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• pp.98-104
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• 1997

대기오염의 장기화에 따라 토양오염이 심화된 것으로 추측되는 서울 남산의 토양을 대기오염이 심하지 않은 것으로 판단되는 계방산 토양의 화학적 특성과 비교하여 남산토양의 오염도를 평가하며, 질소 및 황의 무기화에 관여하는 미생물을 동시에 정량하여 질소 및 황의 무기화에 관여하는 미생물군을 토양오염도 평가기준으로 활용할 수 있는지 알아보았다. 남산의 토양은 계방산에 비하여 10배 이상 수소이온의 농도가 높아 토양 산성화가 상대적으로 심하였다. 특히, 남산토양은 양이온의 용탈이 심하고 치환성 알루미늄은 많아져 남산지역 토양 생태계에 큰 문제가 발생하였음을 나타냈다. 토양 산성화의 주요인은 황산화물의 집적으로 추정되지만 황산환원균의 활성은 지역간에 유의차를 발견할 수 없어서 미생물 동태가 단순한 인자만이 아닌 복합적인 요인에 의하여 조절됨을 짐작할 수 있었다. 반면, 탈질기작에 관여하는 세균의 동태는 남산의 소나무림에 비하여 계방산의 소나무림에서 활발한 것으로 평가되어 토양생태계의 전반적인 미생물 활성도나 건전도의 지표로 질소의 무기화에 관여하는 미생물의 정량기법을 검토해 볼만하다.

• 자원환경지질
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• 제23권2호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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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.

• 한국소음진동공학회논문집
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• 제20권7호
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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.

• 자원환경지질
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• 제30권6호
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• pp.505-517
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• 1997

광신 연-아연 광산은 단층 열극을 충진한 열극 충진 광상으로서 조선계의 삼태산층과 시대미상의 서창리층에 발달된 석영과 탄산엽맥으로 이루어져 있다. 광화작용은 3회에 걸쳐 진행되었으며, 각 광화시기의 특징은 다음과 같다. 광화 I기=barren한 석영의 침전기, 광화 II기=석영과 능망간석에 수반된 연-아연 광물의 주 침전기, 광화 III기=barren한 방해석의 침전기. 특히, 연-아연 광물은 주로 광화 IIb기에 침전하였다. 유체포유물 연구에 의하면, 광화 IIb기 광화유체의 온도와 염농도는 $182^{\circ}{\sim}276^{\circ}C$와 2.7~5.4 wt. % NaCl 상당 염농도였으며, 연-아연 광물의 침전은 주로 비등작용과 더불어 후기의 천수 혼입작용에 기인하였음을 지시한다. 광화작용은 약 600~700 m의 심도에서 이루어진 것으로 판단된다. 섬아연석과 유비철석의 성분 함량을 이용하여 추정한 광화 IIb기의 황분압($log\;fs_2$)은 -15.5~11.8 atm이다. 황화물의 황동위원소 조성 (${\delta}^{34}S_{CDT}=9.0{\sim}14.5$ ‰)에 근거한 열수유체의 전(全) 황동위원소값 (${\delta}^{34}S_{{\Sigma}S}$)은 약 14 ‰로서 매우 높은데, 이는 심부 화성기원의 황이 퇴적암류내의 황산염과 다소 혼합 된 결과로 사료된다. 산소-수소 동위원소 분석 연구에 의하면, 광화유체는 낮은 수-암비 환경 하에서 주로 주변 모암인 삼태산층 (${\delta}^{18}O=20.1{\sim}24.9$ ‰)과 상당히 반응한 심부 순환 천수로부터 형성되었다. 한편, 광화유체의 산소동위원소값 (${\delta}^{18}O_{H2O}$)은 광화작용의 진행과 더불어 체계적으로 감소 (광화 I기, 14.6~10.1 ‰; 광화 IIa기, 5.8~2.2 ‰; 광화 IIb기, 0.8~-2.0 ‰; 광화 IIc기, -6.1~-6.8 ‰)하였다. 이는 열수계 내로의 천수 혼입이 시간 경과와 더불어 점진적으로 증가하였음을 지시한다.