• 한국대기환경학회지
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• 제15권1호
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• pp.23-32
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• 1999

Deposition is one of the important removal mechanisms for the ambient aerosol, and it also leads to adverse environmental and economic impacts. The purpose of this study was to investigate chemical compositions and spatial distributions of fall-out aerosols. A total number of 340 samples were collected at 35 sampling sites in Suwon area from January to November, 1996. Twelve inorganic elements (Al, Ba, Cd, Cr, K, Pb, Sb, Zn, Cu, Fe, Ni, and V) and eight ionic components ($F^-$, Cl, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^+$, $Mg^{2+}$, and $Ca^{2+}$) were analyzed by AAS and IC, respectively. The monthly variation showed that the flux of fall-out particles was increased in the spring season(March, April, and May) and decreased from August to October. Arithmetic mean flux of fall-out particles was 176.8 kg/$ extrm{km}^2$/day during the study period. The fluxes of each chemical species were $SO_4^{2-}$ 12.414, $Ca^{2+}$ 7.369, $NO_3^-$ 5.812, $Cl^-$ 3.566, $NH_4^+$ 3.176, Fe 3.107 kg/$\textrm{km}^2$/day, and so on. By using a kriging analysis, spatial distribution pattern of those fluxes was intensively studied. Total fluxes estimated in Suwon city were 8424.72t/y of fall-out particles, 519.27t/y of $SO_4^{2-}$, 336.79t/y of $Ca^{2+}$,267.34 t/y of $NO_3^+$, 155.36t/y of $Cl^-$, 147.79t/y of Fe.

• 한국대기환경학회지
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• 제28권3호
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• pp.294-305
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• 2012

The objective of this study is to estimate the chemical compositions and to identify qualitative sources of fall-out particles in study area. Also, this study used a spatial analysis to estimate spatial distributions and average deposition flux. In this study, the chemical compositions of fall-out particle samples collected at Muncheon lake from May 2010 to January 2011 were analyzed by ICP and IC. The monthly trend of deposition fluxes for fall-out particles showed highest in June ($107.61kg/km^2/day$) and lowest in October ($22.22kg/km^2/day$). The average fluxes of Fe, Si, Al, Zn and Ba are 0.44, 0.24, 0.20, 0.17, $0.09kg/km^2/day$, respectively. Also, the average fluxes of $NO_3^-$, $SO_4^{2-}$, $NH_4^+$, $Ca^{2+}$, and $Na^+$ are 6.48, 5.01, 4.96, 1.75, $1.37kg/km^2/day$, respectively. A Factor analysis identified four sources such as 1) nonferrous metal, motor vehicle, and agriculture, 2) soil, 3) field burning, incineration, and 4) road dust and oil burning. The IDW (inverse distance weighting) spatial analysis method was used to estimate spatial distribution and average deposition flux for fall-out particles. A total average deposition fluxes estimated in Muncheon lake were 936.15 kg/month. The spatial distribution trend of deposition flux showed higher at site 1 and 2 than at site 3, 4 because local road is adjacent to the site 1 and 2.

• 한국대기환경학회지
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• 제14권6호
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• pp.631-642
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• 1998

Fall-out particles were collected by the modified British deposit gauges at 35 sampling sites in Suwon area from January to November, 1996. Twenty chemical species (Al. Ba, Cd, Cr, K, Pb, Sb, Zn, Cu, Fe, Ni, V, F-, Cl-, NO3-, 5042-, Na+, NH4+, Mg2+, and Ca2+) were analyzed by AAS and If. The purposes of this study were to estimate qualitatively various emission sources of the fell-out particle by applying multivariate statistical techniques such as factor analysis, multiple regression analysis, and discriminant analysis. During the study, outlier sites were determined by a z-score method. Cl-, Na+, Mg2+, and SO42- were highly correlated due to their common marine related source. Wind speed was the most influential factor for the deposition fluxes of the particle itself and all the chemical species as well. When applying the factor analysis, 8 source patterns were qualitatively obtained, such as marine source, soil source, oil burning source, Cr related source, tire source, Cd related source, agriculture source, and F- related source. As a result of the multiple regression analysis, we could suggest that some chemical compounds may possibly exist in the form of CaSO4, NaN03, NaCl, MgC12, (NH4)2SO4, NaF, and CaCl2 in the fall-out particles. Finally, spatial and seasonal classification study performed by a discriminant analysis showed th.at SO42-, Ca2+, Cl-, and Fe were dominant in the group of spatial pattern; however, SO42-, Cl-, Al, and V were in the group of seasonal pattern.

• 방사선산업학회지
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• 제9권2호
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• pp.91-102
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• 2015

The iridium disc, generally used in industrial radiography, is examined to find the fracture morphology and fine particles remaining on the shear blank surface. Randomly selected 1,200 discs were observed under a scanning electron microscope tilted more than $45^{\circ}$. Fracture surfaces are classified into three groups: (1) surface fall-out, (2) fracture on the edge and (3) multi-step brittle fracture, which shows the mutual relationship between the fracture morphology and remaining particles. Fracture particles were removed by cleaning the discs in a ultrasonic bath with acetone and collected at the bottom. Removed number of the particles were counted for each different group of fracture surfaces. Followings are conclusions: (1) About 80.5% of discs (966/1,200), have sound plastic shear surfaces with particles remained. (2) About 2% discs accompany surface fall-out's having large particles tens of ${\mu}m$, which is stable not to be pulled out even after the considerably long time of ultrasonic cleaning. (3) About 5% discs contain the fractures on the edge and the particles are removed thoroughly within 30 minutes. (4) 234 discs out of 1,200 discs have multi-step fracture surfaces whose particles never removed in a short period of time but come out very slowly. Such a disc having multiple-step fracture is attributed to the promate cause to the 'leaker'. It is noted here that the discs having mutiple-step fractures should be treated separately with special care, and it is need to study how to treat them.

• 한국대기환경학회지
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• 제11권3호
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• pp.291-298
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• 1995

An intensive field study was carried out during Aug. 1993 in Seoul to study the characteristics of summertime visibility and diurnal trend of ionic composition of ambient particles. A transmissometer, nephelometer with heated and unheated inlets, PM3 fine particle sampler, and cascade impactor were used to measure optical and particle properties of ambient air. During this study period, a weak smog episode has occurred. Light scattering by particles is the most dominant factor on total light extinction. The effect of light absorption by particles in Seoul is much higher than other major cities in U.S.A. throughout the summer and fall with relatively constant values. The effect of water on $b_{sp}$ was small during the period. The particle size distribution shows a typical bimodal one. Sulfate, ammonium, chloride, and nitrate are the major chemical species in fine fraction aerosols, about 30% of toral mass concentration. Concentraion of sulfate is higher during the daytime while those of nitrate and chloride are higher during the nighttime. Ammonium concentration is constant through the daytime.

• 한국환경보건학회지
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• 제34권2호
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• pp.131-136
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• 2008

The variation of the particle size distribution and density as well as the chemical composition of aerosols is important to evaluate the particles. This study measured and analyzed airborne particles using a scanning mobility particle sizer (SMPS) system and an aerodynamic particle sizer (APS) at the University of Seoul during every season. The highest particle number concentration of airborne particles less than $0.9\;{\mu}m$, occurred in winter, while the highest particle number concentration of airborne particles more than $0.9\;{\mu}m$, occurred in spring. Mass concentration appeared highest at spring. Also, when we compared $\beta$-ray's mass concentration with calculated mass concentration by using the SMPS-APS system during each season, density of the winter is $1.92\;g/cm^3$, spring density is $1.64\;g/cm^3$, fall density is $1.57\;g/cm^3$. We found out that PM10 density was differ every season. However, while the calculated density is whole density for PM10 the density of each diameter was different. In this study the density estimation equation of the QCM cascade impactor measured mass concentration of each diameter.

• 한국컴퓨터그래픽스학회논문지
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• 제25권3호
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• pp.31-41
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• 2019

포그 스크린은 미세한 물방울들로 구성된 스크린으로 관찰자는 포그 스크린을 투과한 영상을 관찰하게 된다. 일반 스크린과는 달리 관찰자는 무대 위에서 연기자가 포그 스크린에 표시된 이미지를 뚫고 들어가는 모습을 볼 수 있다. 본 논문에서는 상부에서 생성된 포그 입자 집단이 중력에 의하여 아래로 떨어질 때 평평한 수직 스크린을 이루도록 하는 하향식 포그 스크린 생성 장치 구현 방법을 기술한다. 본 기법은 수조안에 배치된 초음파 진동자에 의해 수조 표면에서 포그 입자가 발생되는 원리를 이용한다. 생성된 포그 집단이 하나의 평면을 유지할 수 있도록 포그가 나오는 통로 출구 양옆에 가이드 바람을 형성하는 기법과 포그 스크린 생성 장치의 설계와 제작 방법을 기술한다.

• 한국대기환경학회지
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• 제14권6호
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• pp.621-630
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• 1998

The concentrations of organic carbon (OC) and elemental carbon (EC) in fine aerosols were determined from the samples collected at the two background sites of Kosan in Cheju Island and Kangwha. Samplings were carried out during the spring and winter of 1996 and the fall and winter of 1997. PM25 particles were collected on the prefired quartz filters for 24 hours and analyzed by the selective thermal oxidation method. The concentrations of OC at the sites were higher than those commonly observed from clean areas around the world, but those of EC at both sites were lower than, or comparable to, other clean areas in the world. Both the OC and EC levels at Kangwha were higher than those at Kosan. According to backward trajectory analysis, most air pollutants collected at the two sites were from China. It was found that the OC and EC concentrations in air masses from southern China were higher than those from northern China.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.592-599
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• 2004

Talus topography is that weathered rock clasts were accumulated dropping in steep slope to action of gravity. Rock fall talus is formed by the accumulation of rock debris falling as individual particles from a cliff. If the collapse is produced in talus slope. it will be possible the loss of manpower and country. Despite correct access about talus is required, domestic research was scientific access about talus short because of short resolution of aerophoto and difficulties of research about huge talus. In this Study, Our research team analgize the wetness index using the geomorphogical data. Lineament through wetness index is simillar with distribution of the talus. And, the aim of the present study is to review and compare fabric data derived from rock fall talus about orientation, distribution and morphology. These deposits tend to have approximately equal amounts of clasts oriented parallel and perpendicular to the dip direction of the slope. And, platy- shaped clasts dominate the proximal and intermediate parts of the talus, wheres blocky-shaped clasts is more common in the distal part. we carry out Rock Fall Simulation. And, We install criteria of the rockfall protective barrier using talus and geomorphological characteristics.

• 환경위생공학
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• 제14권4호
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• pp.158-164
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• 1999

This study was carried out to investigate total suspended particulates (TSP) in Iksan area collected by nine stages Anderson air sampler and High volume air sampler from Jul. 1996 to Jul. 1998.The results are as follows1. The average of TSP concentration to be collected by Anderson air sampler and High volume air sampler in Iksan city are $59{\mu}g/m^3$, $67{\mu}g/m^3$. It was below the level of environmental standard. 2. The average of TSP concentration by measured method are HVAS > AS > Gov. 3. The average of TSP concentration on seasonal change are higher spring than winter. It were $65.5{\mu}g/m^3$ of Spring, $57{\mu}g/m^3$ of Summer, $52.5{\mu}g/m^3$ of Fall, $61{\mu}g/m^3$ of Winter. 4. Particle size 3istribution of atmospheric particulate was divided into two groups, coarse group was made by particles larger than $1.1-2.1{\mu}m$ in diameter and fine groups smaller than $1.1-2.1{\mu}m$ in diameter. about 50% of total suspended particle measured by Anderson air sampler during the sampling period was coarse particle.