• 한국대기환경학회지
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• 제33권4호
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• pp.326-332
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• 2017

$SF_6$ (sulfur hexafluoride) gas has an extremely high global warming potential (GWP). Therefore, there has been an effort to reduce of $SF_6$ its emission into atmosphere. In this study, $SF_6$ was injected into the plasma reactor directly, decomposed particulate matter of $SF_6$ was analyzed. Destruction and removal efficiency (DRE) of $SF_6$ were tested with varying degrees of plasma power and initial concentrations of $SF_6$ (1,000 ppm). This study is conducted with plasma power which are 4.4 kW, 5.5 kW, 6.0 kW, 6.6 kW, 7.6 kW, 8.1 kW and 9.1 kW. It was confirmed through experiment that the decomposition efficiency of $SF_6$ is 100% at 7.6 kW of the plasma power. In addition, the particulate matter is formed as minute particles of which size is $1{\mu}m$ and the main component of particulate matter is identified as $AlF_3$.

• 한국환경보건학회지
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• 제36권4호
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• pp.306-312
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• 2010

This field study was performed to evaluate the efficiency of a plasma ion-operated air cleaner in temporal reduction of airborne pollutants emitted from a pig housing facility. In the case of gaseous pollutants, the plasma ion air cleaner was not effective in reducing levels of ammonia, hydrogen sulfide, nitrogen dioxide, or sulfur dioxide (p>0.05). In the case of particulate pollutants, however, the air cleaner was effective in reducing levels of particulate matter ($PM_{2.5}$ and $PM_1$) by 79(${\pm}6.1$) and 78(${\pm}3.0$)%, respectively. Unlike the case of these fine particle fractions, the reduction of total suspended particles (TSP) and $PM_{10}$ following treatment was almost negligible. In the case of biological pollutants, the mean reduction efficiencies for airborne bacteria and fungi were relatively low at 22(${\pm}6.6$) and 25(${\pm}8.7$)%, respectively. Taken together, these results indicate that in terms of air pollutants released from this pig housing facility, the plasma ion air cleaner was primarily effective in reducing levels of $PM_{2.5}$ and $PM_1$.

• 한국환경과학회지
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• 제12권2호
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• pp.217-225
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• 2003

Samples of size-fractionated PM10 (airborne particulate matter with aerodynamic diameter less than $10\mu\textrm{m}$) were collected at an urban site in Jeju city from May to September 2002. The mass concentration and chemical composition of the samples were measured. The data sets were then applied to the CMB receptor model to estimate the source contribution of PM10 in Jeju area. The average PM10 mass concentration was 28.80$\mu\textrm{g}/m^3$ ($24.6~33.49\mu\textrm{g}/m^3$), and the FP (fine particle with aerodynamic diameter less than $2.l\mu\textrm{m}$ fraction in PM10 was approximately 8% higher than the CP (coarse particle with aerodynamic diameter greater than $2.l\mu\textrm{m}$ and less than $10\mu\textrm{m}$ fraction in PM10. The CP composition was obviously different from the FP composition, that is, the most abundant water soluble species was nitrate ion in the FP, but sulfate ion in the CP. Also sulfur was the most dominant element in the FP, however, sodium was that in the CP. From CMB receptor model results, it was found that road dust was the largest contributor to the CP mass concentration (45% of the CP) and ammonium nitrate, domestic boiler, and marine aerosol were major sources to the CP mass. However, the secondary aerosol was the most significant contributor to the FP mass concentration (45% of the FP). In this study, it was suggested that the contributions of soil dust and gasoline vehicle became very low due to collinearity with road dust and diesel vehicle, respectively.

• 한국의류학회지
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• 제35권11호
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• pp.1297-1308
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• 2011

This research investigates the application of ZnO (zinc oxide) nanoparticles and $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via an electrospinning technique for the development of textile materials that can decompose harmful gases. To fabricate uniform ZnO nanocomposite fibers, two types of ZnO nanoparticles were applied. Colloidal $TiO_2$ nanoparticles were chosen to fabricate $TiO_2$ nano- composite fibers. ZnO/poly(vinyl alcohol) (PVA) and $TiO_2$/PVA nanocomposite fibers were electrospun under a variety of conditions that include various feed rates, electric voltages, and capillary diameters. The morphology of electrospun nanocomposite fibers was examined with a field-emission scanning electron micro- scope and a transmission electron microscope. Decomposition efficiency of gaseous materials (formaldehyde, ammonia, toluene, benzene, nitrogen dioxide, sulfur dioxide) by nanocomposite fiber webs with 3wt% nano-particles (ZnO or $TiO_2$) and 7$g/m^2$ web area density was assessed. This study shows that ZnO nanoparticles in colloid were more suitable for fabricating nanocomposite fibers in which nanoparticles are evenly dispersed than in powder. A heat treatment was applied to water-soluble PVA nanofiber webs in order to stabilize the electrospun nanocomposite fibrous structure against dissolution in water. ZnO/PVA and $TiO_2$/PVA nanofiber webs exhibited a range of degradation efficiency for different types of gases. For nitrogen dioxide, the degradation efficiency was 92.2% for ZnO nanocomposite fiber web and 87% for $TiO_2$ nanocomposite fiber web after 20 hours of UV light irradiation. The results indicate that ZnO/PVA and $TiO_2$/PVA nano- composite fiber webs have possible uses in functional textiles that can decompose harmful gases.

• Korean Chemical Engineering Research
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• 제57권6호
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• pp.853-860
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• 2019

나날이 엄격해지는 환경 규제를 만족시키기 위하여, 고체 입자를 유체처럼 이용하는 순산소 순환유동층 및 초초임계 순환유동층 발전 기술이 전세계에서 개발되고 있다. 순환유동층 발전 공정들에서 미세먼지, 산성비의 주범으로 알려진 황산화물을 저감하는 전통적인 방법은 황산화물과 반응하는 석회석을 보일러 내에 직접 주입하는 것이다. 그러나 보일러 내에 주입된 석회석은 다양한 조업 변수들(온도, 압력, 고체 순환속도, 층밀도, 체류시간 등)의 영향을 받아 탈황 성능이 지속적으로 변화하게 된다. 이에 본 연구에서는 기존에 발표된 탈황 반응 속도식과 순환유동층의 수력학적 특성식들을 결합하여 순환유동층 보일러에서 석회석과 순환유동층 운전 특성들만으로 탈황 효율을 예측하는 식을 개발하였다. 특히 다양한 국내 석회석들의 탈황 반응들로부터 얻어진 실험 결과들을 이용하여 탈황 효율 예측식을 개선하였다.

• Advances in materials Research
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• 제11권3호
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• pp.225-235
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• 2022

It includes the synthesis of pristine ZnO nanoparticles and a series of Ag-doped zinc oxide nanoparticles was carried out by reflux method by varying the amount of silver (1, 3, 5, 7 and 9% by mol.). The morphology of these nanoparticles was investigated by SEM, XRD and FT-IR techniques. These techniques show that synthesized particles are homogenous spherical nanoparticles having an average particle size of about 50-100 nm along with some agglomeration. The photocatalytic activity of the ZnO nanoparticles and Ag doped ZnO nanoparticles were investigated via photodegradation of methylene blue (MB) as a standard dye. The data from the photocatalytic activity of these nanoparticles show that 7% Ag-doped ZnO nanoparticles exhibit much enhanced photocatalytic activity as compared to pristine ZnO nanoparticles and other percentages of Ag-doped ZnO nanoparticles. Furthermore, 7% Ag-doped ZnO was made composites with sulfur-doped graphitic carbon nitride by physical mixing method and a series of nanocomposites were made (3.5, 7.5, 25, 50, 75% by weight). It was observed that the 25% composites exhibited better photocatalytic performance than pristine S-g-C 3 N 4 and pure 7% Ag-doped ZnO. Tauc's plot also supports the photodegradation results.

• Asian Journal of Atmospheric Environment
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• 제7권2호
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• pp.120-128
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• 2013

The concentration and composition of particulate matter (PM) in the atmosphere can directly reflect the environmental pollution. The atmospheric pollution in some Cameroonian cities is increasing with the industrial development and urbanization. Air pollution is inherently complex, containing PM of varied size and composition. This PM exists as a dynamic cloud interacting with sunlight and is modified by the meteorology. The reflectometer and the EDXRF spectrometry are applied to determine the concentration of some specific elements at four sites in the city of Yaound$\acute{e}$. The particular aim of the present work is to put in place data base on air pollution in urban area and elaborate regulations on the emissions issued to industrial and vehicle activities. This study provides an overview of the concentration of black carbon and some specific elements in the air, which have impacts on human health. The measurement was done by distinguishing the size of particle. So that, the particle with aerodynamic diameter between $2.5-10{\mu}m$ (so-called coarse particle) and aerodynamic diameter < $2.5{\mu}m$ (so-called fine particle) were considered to obtain more information about levels of the inhalable fraction of the location. The results obtained in four locations of the city of Yaound$\acute{e}$ show that the black carbon concentration is very considerable, the element sulfur is a major pollutant and the concentration of fine particle is very greater. The results obtained of fine and coarse filters range from $5-17{\mu}g/m^3$ and $10-18{\mu}g/m^3$ for the black carbon. S, Cu, Zn, Pb, Cd, As, Se and Hg are the specific findings of this work. The pollutants with a greater concentration are S, Pb, and Zn. These later seem to be non-uniformly, non-regular in some location and high compared to other countries. This work allows us to make a potential relation between pollutants and emission sources. In this framework, some suggestions have been proposed to reduce emissions for an improvement of the air quality in the environment and thus, the one of the city of Yaound$\acute{e}$.

• 해양환경안전학회지
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• 제26권6호
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• pp.706-714
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• 2020

전 세계 90 %의 인구가 WHO의 연평균 미세먼지 노출 기준(10 ㎍/㎥)을 초과한 공기를 흡입하고 있다. 전 세계적으로 육상뿐만 아니라 해양에서 발생하는 질소산화물에 대한 규제를 통해 2차 오염물질, 초미세먼지 저감에 대해 노력하고 있으며 국내에서는 선박에서 미세먼지 발생의 주요한 원인인 황 함유량 저감과 환경친화적 선박의 개발 및 보급 등을 통해 깨끗한 해양환경 조성을 위한 노력을 하고 있다. 디젤엔진 유해 배출가스 저감을 위한 기술 중 압력 손실이 적고 높은 집진 효율 및 NOx의 제거와 유지 관리의 장점이 많은 전기 집진기의 수요와 중요성이 증가하고 있다. 본 연구는 총톤수 999톤급 선박의 2,427 kW 선박용 디젤엔진의 미세먼지 저감을 목적으로 개발된 전기 집진기를 예지보전단계에서 고장모드영향분석을 통해 장비 품질을 높여 선박 내에서의 내구연한을 높이고자 위험 우선순위 도출하였다. 위험 우선순위는 고장모드 241(poor dust capture efficiency)이 RPN 180으로 가장 높았다. Collecting electrode에서 가장 많은 고위험 고장모드를 검출하여 집중관리 부품으로 관리해야 할 필요가 있었으며 원인으로 진동과 핀 풀림으로 인한 유격 불량이 가장 많이 검출되었다. 핀 풀림 역시 근본적으로는 선체 또는 장비에서 발생하는 진동이 원인이 되어 발생할 수 있는 사항이기 때문에 핀 풀림이 발생하는 개소에 보완이 필요하겠다.

• Korean Chemical Engineering Research
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• 제48권1호
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• pp.20-26
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• 2010

수용성 유기 및 무기성분은 대기 에어로졸 입자의 중요한 구성성분들이며 간접적으로 기후에 영향을 미치는 구름응결핵으로 작용한다. 유기 및 원소탄소(organic and elemental carbon, OC 및 EC) 및 수용성 유기탄소(water soluble OC, WSOC) 및 이온성분농도를 조사하기 위하여 광주지역에서 24시간 기준의 미세입자($PM_{2.5}$)를 측정하였다. 측정기간 중 $PM_{2.5}$ 수용성 분율의 주요성분인 WSOC, $NO_3^-$, $SO_4^{2-}$ 및 $NH_4^+$의 평균농도는 각각 2.11, 5.73, 3.51 및 $3.31{\mu}g/m^3$ 이었으며, $PM_{2.5}$ 농도의 12.0(2.9~23.9%), 21.0(12.9~37.6%), 11.6(2.5~25.9%), 및 11.7%(3.8~18.6%)를 차지하였다. 총 수용성 성분(유기+무기) 중 WSOC 화합물이 차지하는 분율은 평균 17.6%(5.4~35.9%)이었다. EC 추적자 기법을 이용해 평가한 2차 OC 및 WSOC 농도는 각각 평균적으로 0.78 및 $0.34{\mu}g/m^3$이었으며, 전체 OC 및 WSOC 중의 평균 17.9%(범위: 0~44.4%) 및 평균 11.2%(범위: 0~51.4%)를 차지하였다. 광주지역 겨울철에 측정한 $SO_4^{2-}$ 입자는 국지적인 기상산화반응보다는 장거리 이동 또는 수용액 변환과정에 의한 영향, 구름 내 변환과정 등이 황산염 입자 생성에 중요하게 작용했을 것으로 판단한다.

• Elastomers and Composites
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• 제49권1호
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• pp.1-12
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• 2014

전투기 연료필터의 막힘은 조종사 생명과 전투기의 손실에 큰 영향을 줄 수 있다. 따라서 결함 연구는 사고를 미연에 방지하는데 매우 중요하다. 전투기 연료필터는 제트 연료에 포함된 다양한 불순물을 여과하는 중요한 기능을 수행한다. 연료 필터는 시간당 1,330 파운드의 유속으로 공급되는 제트 연료에 함유된 10 ${\mu}m$ 크기 이하의 불순물을 여과한다. 필터는 운영시간 기준 500 시간마다 교체되어야 한다. 그러나 500 시간이 도달하기 훨씬 전에 연료 필터의 막힘 현상으로 경고등이 켜지고 있다. 이와 같은 유사한 결함이 최근에 반복적으로 발생하고 있다. 그러므로, 이 연구에서는 전투기의 연료 필터 막힘에 대한 원인을 FT-IR microcopy, FE-SEM/EDS, 총 황함량 분석기와 같은 다양한 분석기술을 이용하여 조사하였다. 결론적으로, 연료 필터를 막히게 한 물질은 내부 연료 탱크용 실란트에서 기인한 가류 촉진제로 확인되었다. 그리고 연료 탱크내에서 가류 촉진제 블루밍 현상에 의해 연료필터를 막히게 하는 물질의 형성에 대한 메커니즘을 제시하였다.