• 한국입자에어로졸학회지
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• 제8권1호
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• pp.29-35
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• 2012

The Faraday cup electrode of different size has been developed and evaluated to investigate the diffusion effect of particles by Brownian motion in a particle beam mass spectrometer(PBMS). Particles which focused and accelerated by aerodynamic lens are charged to saturation in an electron beam, and then deflected electrostatically into a Faraday cup detector for measurement of the particle current. The concentration of particles is converted from currents detected by Faraday cup. Measurements of particle current as a function of deflection voltage are combined with measured relationships between particle velocity and diameter, charge and diameter, and mass and diameter, to determine the particle size distribution. The particle currents were measured using 5, 10, 20, 40 mm sized Faraday cup that can be move to one direction by motion shaft. The current difference for each sizes as a function of position was compared to figure out diffusion effect during transport. Polystyrene latex(PSL) 100, 200 nm sized standard particles were used for evaluation. The measurement using 5 mm sized Faraday cup has the highest resolution in a diffusion distance and the smaller particles had widely diffused.

• 한국환경보건학회지
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• 제32권6호
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• pp.543-555
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• 2006

During a twenty-day period in 2005, a nine-stage Andersen cascade impactor was used to determine the seasonal size distribution of atmospheric particles and its inorganic ion species sampled for 24hr in Iksan city, located southwest of the Korean peninsula. Samples were analyzed for major water-soluble ion species using Dionex-100 ion chromatograph. Average fine and coarse mass concentrations of atmospheric particles were, respectively, 31.4 and $82.6{\mu}g\;m^{-3}$ in spring and 35.8 and $73.4{\mu}g\;m^{-3}$ in fall-winter during the sampling period of 2005, while measurements of 69.8 and 9.9 were obtained in the sampling period of summer, The size distribution of particulate mass concentration during the non-Asian dust period was generally bimodal, whereas the size distribution of particulate mass concentration during the Asian dust period was unimodal due to the significant increase of coarse particles, which originated from long-range transport of soil dust particles from loess regions of the Asian continent. Among ionic species, $SO{_4}^{2-},\;NH{_4}^+,\;K^+$ were mainly distributed in fine particles due to their characteristics of emission sources and gas-to-particle conversion, while $Na^+,\;Mg^{2+}\;and\;Ca^{2+}$ were dominantly in coarse particles. However, $NO_3{^-}\;and\;Cl^-$ were distributed in both coarse particles and fine particles. Although $SO{_4}^{2-}$ was mainly distributed in fine particles, the size distributions of $SO{_4}^{2-}$ in coarse mode were significantly increased during the Asian dust events compared to those during the non-Asian dust period. $Ca^{2+}$ showed the most abundant species in the atmospheric particles during the Asian dust period. $NH{_4}^+$ was found to mainly exist as $(NH_4)_2SO_4$ in fine particles.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2077-2083
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• 2022

In the unlikely event of core disruptive accident in sodium cooled fast reactors, the reactor containment building would be bottled up with sodium and fission product aerosols. The behavior of these aerosols is crucial to estimate the in-containment source term as a part of nuclear reactor safety analysis. In this work, the evolution of sodium aerosol characteristics (mass concentration and size) is simulated using HAARM-S code. The code is based on the method of moments to solve the integro-differential equation. The code is updated to FORTRAN-77 and run in Microsoft FORTRAN PowerStation 4.0 (on Desktop). The sodium aerosol characteristics simulated by HAARM-S code are compared with the measured values at Aerosol Test Facility. The maximum deviation between measured and simulated mass concentrations is 30% at initial period (up to 60 min) and around 50% in the later period. In addition, the influence of humidity on aerosol size growth for two different aerosol mass concentrations is studied. The measured and simulated growth factors of aerosol size (ratio of saturated size to initial size) are found to be matched at reasonable extent. Since sodium is highly reactive with atmospheric constituents, the aerosol growth factor depends on the hygroscopic growth, chemical transformation and density variations besides coagulation. Further, there is a scope for the improvement of the code to estimate the aerosol dynamics in confined environment.

• 한국입자에어로졸학회지
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• 제8권4호
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• pp.151-160
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• 2012

Health effects caused by the ultrafine particles in ambient air are great concern to the public health, and the strict measuring and monitoring of the ambient aerosol are required. In this work, the characteristics of the aerosol size distribution in Pohang province are studied. Optical particle counters (Grimm APS 1108 and 1109) were used to measure the aerosol size distribution in the area. Locations near the national monitoring site located in the industrial and the residence area were selected for the measuring sites of this study, and the locations in border area between the industry and the residence were selected for the reference of the comparison. In the industry site, it is found that the concentration of aerosol particles near the size of 5 ${\mu}m$ appear characteristically and the fluctuations in concentration with respect to time are minimal. The mass concentration of the aerosol above 10 ${\mu}m$ in diameter in the industry area was found to fluctuate significantly. The mass portion of $PM_{10}$ and PM2.5 to TSP in the residence area were 83% and 51% respectively. In the industrial regional, it was found that the mass portion of PM10 and $PM_{2.5}$ to TSP were 76% and 35% respectively. In the boundary area the mass portion of $PM_{10}$ and $PM_{2.5}$ to TSP were 78% and 54% respectively.

• Journal of Biosystems Engineering
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• 제20권3호
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• pp.236-244
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• 1995

Droplet size is one of the important factors in the deposition and drift of agrichemical application. In this study, droplet size and its distribution of the three different sizes of ceramic hollow cone nozzles being used in the air carrier sprayer for apple production were investigated at the various nozzle pressures and the three air velocities. The Malvern particle size analyzer were used for the measurement of droplet size and its distribution. The important results emerged from th is study can be summarized as follows. 1. Discharged rate was increase with the increase of the nozzle diameter and pressure, amount of the difference was remarkable between the nozzle diameter of 1.0, 1.2 and 1.5 mm, but no difference were found between the diameter of 1.0 and 1.2 mm in the same nozzle pressure. 2. Mass median diameter were varied as 40~160 ${mu}m$ at the air velocity of 0 m/s, 70~140 ${mu}m$ of 15 m/s and 100~160 ${mu}m$ of 20 m/s 3. It appeared that the air velocity range of 15~20 m/s was desirable for both drift and deposition control in the given experimental conditions.

• Journal of Ecology and Environment
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• 제32권3호
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• pp.177-182
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• 2009

The optimal strategy for semelparous females may involve adjustments in the relative investment in two fitness components, the number of offspring and the post-hatching investment per capita. To determine the pattern of maternal resource allocation to offspring in the matriphagous spider, Amaurobius ferox (Amaurobiidae), I investigated the relationship between maternal body-mass and the number of offspring, and quantified the transfer of maternal body-mass to the offspring via different forms of maternal provisioning (trophic egg-laying and matriphagy). There was a positive relationship between female body-mass and the number of offspring. However, Amaurobius mothers did not produce more trophic eggs when they had larger broods. Rather, spiderlings in larger A. ferox broods consumed larger quantities of maternal body-mass via matriphagy. Mothers transferred $28.8{\pm}6.5%$ of their body-mass to the spiderlings via trophic egg-laying, and an estimated $39.0{\pm}12.5%$ of their body-mass was transferred to the spiderlings via matriphagy.

• 한국산학기술학회논문지
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• 제9권5호
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• pp.1349-1353
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• 2008

충청남도, 천안시 대기 에어로졸의 입경별 농도 및 이온성분 특성을 분석하고자, 2006년 3월부터 2007년 4월까지 천안시 상명대학교에서 Cascade Impactor를 장착한 High Volume Air Sampler를 이용하여 대기 시료를 채취 분석하였다. 입경별 에어로졸의 일평균농도는 TSP, PM10, PM2.5, PM1이 각각 61.7, 55.2, 43.7, $33.2{\mu}g/m^3$였으며, 직경이 $1{\sim}3{\mu}m$인 영역을 경계로 조대영역과 미세영역으로 나누어지는 전형적인 도심지 특성을 나타냈다. 이 중 미세영역입자인 PM2.5이 전체 에어로졸의 70.8%를 차지하였다. 이들 에어로졸 입자의 성분 분석 결과 양이온은 ${NH_{4}}^+$, $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$이, 음이온은 ${SO_{4}}^{2-}$, ${NO_{3}}^-$, $Cl^-$가 주요 성분이었으며, 이들 수용성 이온이 차지하는 비율은 조대입자에서 37.4%, 미세입자에서 46.2%였다.

• 한국대기환경학회지
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• 제34권5호
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• pp.677-686
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• 2018

An intensive measurement was conducted to study the mass and number concentrations of atmospheric aerosols in Anheung ($36.679^{\circ}N$, $126.186^{\circ}E$), the west coastal measurement site of Korea during December 2017~April 2018. To evaluate relationships between the aerosols and meteorological parameters, comparisons of Optical Particle Counter (OPC) measured data and Auto Weather System (AWS) data were performed. Measured PM mass concentrations are $PM_{10}=42.814{\pm}30.103{\mu}g/m^3$, $PM_{2.5}=29.674{\pm}25.063{\mu}g/m^3$, $PM_1=28.958{\pm}24.658{\mu}g/m^3$, respectively. The PM ratios showed that the $PM_{10}$ concentrations contained about 67.8% of $PM_{2.5}$, while most part of $PM_{2.5}$ was $PM_1$ (about 97.1%). Timely collocation with AWS data were performed, exploring relations with the PM concentrations. PM concentrations can be explained by wind direction and relative humidity conditions. The significant reductions of fine particles in mass and number concentrations may attribute to actions on particle growth and wet removal. In these results, we suppose that the aerosol concentrations and size distributions are affected by inflow direction and air mass sources from the origin.

• Journal of Chest Surgery
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• 제20권3호
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• pp.593-597
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• 1987

Mesothelioma is a primary tumor of the pleura. There are two forms of mesotheliomas; diffuse form and localized form. The majority of localized mesotheliomas are benign, but the tumor with pedicle recur at 20% after removal of it. Malignant localized fibrous mesothelioma is differential diagnosed pathologically and clinically with diffuse mesothelioma. Symptoms of localized mesothelioma are generally related to the size of the tumor. We presented one case of malignant localized fibrous mesothelioma. The patient was 32 years old female and chief complaints were dyspnea and dry cough. Sputum cytology and needle lung biopsy were not able to diagnose definitely the tumor. Explothoracotomy was carried out for definite tissue biopsy. At the time of operation, huge adult head size mass was in the right thoracic cavity. The surface of the mass was nodular, multilobular and had hard consistency. Pedicle was formed above first rib and its diameter was 4.5cm. There was no adhesion except to RUL. Frozen biopsy suggested mesothelioma. Extirpation of the mass, right upper lobectomy. and partial pleurectomy were carried out.

• 터널과지하공간
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• 제12권3호
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• pp.198-209
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• 2002

To assess deep geological environment for the research and development of hish-level radioactive waste disposal, six boreholes of 3" in diameter were installed in two granitic areas. An areal extent of the rock block scale in the study sites was estimated by the lineament analysis from satellite images and shaded relief maps. The characterization of fracture system developed in rock block scale was carried out based on the acoustic televiewer logging in deep boreholes. In the Yuseong site, the granite rock mass was divided into the upper and lower zones at around -160m based on the probabilistic distribution characteristics of the geometric parameters such as orientation, fracture frequency, spacing and aperture size. Since the groundwater flow is dependent on the fracture system in a fractured rock mass, the correlation of the fracture frequency and cumulative aperture size to the hydraulic conductivity was also discussed.