• 한국입자에어로졸학회지
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• 제19권4호
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• pp.145-154
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• 2023

Granular bed filters are widely used to remove particulate matter in flue gas and are filled with various shapes of packing material. The packing material plays an important role in determining the overall collection performance, such as pressure drop and collection efficiency. The pressure drop of a granular bed filter has been calculated using the Ergun equation, while the collection efficiency has been predicted using the log-penetration equation based on the single sphere theory. However, a prediction equation of collection efficiency for a granular bed filter filled with non-spherical packing materials has not been suggested yet. Therefore, in this study, three different shapes of packing materials (sphere, cylinder, and irregular) were prepared to propose a prediction equation. The pressure drop and collection efficiency in a granular bed filter filled with each shape of packing material were measured experimentally and compared with theoretically predicted values. We found that experimentally measured pressure drops matched well with values theoretically predicted using the Ergun equation considering the shape factor. However, experimental collection efficiencies were higher than theoretical ones predicted by the log-penetration equation using the single sphere theory. We modified the log-penetration equation by employing a shape factor and found a good relationship between experimental and theoretical collection efficiencies.

• 대한환경공학회지
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• 제27권12호
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• pp.1270-1276
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• 2005

대기 중 PAHs의 가스/입자 분배반응이 평형상태일 때 가스/입자분배계수($logK_p$)와 각 화합물의 증기압($logP_L^O$)과 선형식의 기울기가 -1이라는 것이 지금까지 알려진 사실이었다. 기러나 실제 대기에서 일어나는 가스/입자 분배와 차이를 보이는 현상에 대한 연구가 진행되면서 대기 입자의 불균일성 및 입자특성의 차이로 평형상태일 때 가스/입자 분배계수와 증기압과 기울기가 -1이 되지 않을 수도 있다는 주장이 제기되었다. 따라서 본 연구에서 이러한 가설을 토대로 대기 입자의 입경 크기에 따라 시료를 채취하여 평형상태일 때 입경의 크기에 따른 가스/입자 분배를 연구하였다. 대기 중 PAHs의 분배평형상태를 추정하기 위해 High-volume air sampler에서 채취된 입자와 가스를 이용하여 분배계수와 증기압을 구하고 이때 기울기가 -1에 가까운 시료를 평형상태에 있는 시료로 간주하였다. 그러나 평형상태에 해당하는 시료 중 같은 날 동시에 채취한 입경별 입자를 이용하여 각 입경 크기에 따라 분배계수와 증기압의 기울기를 계산한 결과에서는 평형상태일지라도 입경크기에 따라 동일한 기울기를 갖지 않고 입자가 커질수록 기울기가 완만해지는 현상을 나타내었다. 이러한 현상을 규명하기 위해 가스/입자 분배 반응의 두 가지 기작에 대하여 평형상태일 때 기울기가 -1이라는 결과를 도출하기 위해 가정했던 조건에 대하여 검토하였다. 그 결과 가스/입자 분배가 흡착이 주 반응이라 가정했을 때 입자의 크기에 따라 탈착엔탈피 변화량에 차이가 있었으며, 흡수인 경우에는 입자간의 활성계수의 차이를 간접적으로 확인할 수 있었다. 이는 평형상태일 경우에도 입자의 크기에 따라 가스/입자 분배평형에 이르는 정도가 다른 것으로 판단된다. 또한 가스/입자 분배반응 현상을 규명하기 위해서는 입자의 크기를 고려함으로써 그 현상을 좀 더 명확히 밝힐 수 있을 것으로 판단된다.

• 한국초등과학교육학회지:초등과학교육
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• 제37권2호
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• pp.147-160
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• 2018

The purpose of this study is to compare the elementary science curriculum and textbooks of Korea, the United States, Japan, and Singapore to know how the contents on particulate concept of matter is introduced and expressed. In Korea, particulate concept of matter was adopted as a term for 'molecules' in the 3rd through 6th curriculum, and the term for 'particles' was adopted in the 2009 revised curriculum. In the United States, NGSS adopted the term 'particle' in fifth grade. Japan presented the concept of 'particle' as a core concept of matter in the commentary, and the expressions 'particles' were being introduced in the textbooks. But it did not cover particulate nature of matter at the elementary school level in Singapore. An analysis of elementary textbooks in Korea, the United States and Japan except Singapore showed particulate expressions in 'dissolution', 'state change of water', 'gas pressure and volume', 'combustion and extinguishment' units. Korean textbook was only being introduced in 'dissolution' and 'gas pressure and volume', but in the textbooks of Japan and the United States, water was expressed as particles in 'state change of water' unit. Discussion and implication on the introduction of particulate concept to elementary science curriculum and textbooks were suggested based on the results.

• 한국환경과학회지
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• 제18권11호
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• pp.1299-1307
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• 2009

In order to measure in-situ suspended particle size, volume concentration of suspended particulate matter and current speed, mooring observation was performed at the Gwangyang Bay by using of an optical instrument, 'LISST-100' and an acoustic instrument, 'ADV'(St. S1). And the sediment flux was obtained based on the concentration of suspended particulate matter and current speeds measured at three lines of Gwangyang Bay during ebb and flood tide of August 2006. To investigate the spatial variation of suspended particulate matter, profiling observations were measured difference echo intensity and beam attenuation coefficient by using of ADCP and Transmissometer (Line A, B, C). The suspended sediment flux rate at the mouth of Gwangyang Bay was observed to be higher during asymmetrical than symmetrical of current speeds. The flux of suspended particulate matter concentration and current speeds were transported to southeastern direction of surface layer and northwestern direction of bottom layer at the western area at line A of Gwangyang Bay. Small suspended particles have been found to increase attenuation and transmission more efficiently than similar large particles using acoustic intensity (ADV/ADCP) or optical transmit coefficient (LISST-100/Transmissometer). The application and problems as using optical or acoustic instruments will be detected for use in time varying calibrations to account for non-negligible changes in complex environments in situ particle dynamics are poorly understood.

• 한국해양환경ㆍ에너지학회지
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• 제11권3호
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• pp.124-131
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• 2008

2003년 8월과 2004년 9월 제주도 남서부해역과 중국 연안해역을 대상으로 실시된 본 연구는 용존무기영양염류와 용존 및 입자유기탄소의 분포 특성을 조사하였다. 하계에 동중국해의 영양염의 분포 형태는 수괴 및 식물플랑크톤의 영향을 받은 것으로 밝혀졌다. 하계에 동중국해내 수괴들은 중국의 연안해역을 제외하고 상하수직혼합이 잘 일어나지 않아 표층수에는 영양염의 유입이 감소하고, 저층수에는 표층에서 유입되는 유기물이 분해되어 영양염의 축적이 일어나 높은 농도를 나타내고 있었다. Chlorophyll a의 농도가 높은 해역에서 영양염의 농도가 낮은 값을 보였으며, Chlorophyll a의 농도가 감소하는 수심이하에서 영양염의 농도가 증가함을 보여 높은 생물활동에 의한 무기영양염류 등이 조절되고 있는 것으로 생각된다. 연구해역내 용존유기탄소의 분포는 염분이나 수온에 대해 다소 산만한 분포를 보여 수괴에 따른 상관관계가 없는 것으로 조사되었고, 양자강 영향 정점에서 $100{\mu}M$이상의 높은 값을 보인 반면, 제주도 남서부 해역에서는 낮은 농도를 보였는데, 이것은 양자강 유출수가 동중국해 용존유기탄소의 공급원으로 작용하고 있는 것으로 사료된다. 연구해역 입자유기탄소의 분포특성은 양자강 유출수가 영향을 미치는 중국연안해역에서 평균 $9.23{\mu}M$로 가장 높은 농도를 보였으며, 대마난류수의 영향을 받는 제주도 남동부해역에서 $3.04{\mu}M$로 낮은 농도를 보였으며, 중앙부해역에서 $7.23{\mu}M$의 입자유기탄소량을 나타내, 양자강 유출수가 자생적 기원이외의 입자유기탄소 공급원으로 작용하고 있는 것으로 사료된다. 제주도 남서부해역에서의 입자유기탄소는 Chlorophyll a의 농도와 높은 상관성을 보여 자생적 기원으로 볼 수 있지만 그 해역에서의 염분도가 저염(30%o 이하)을 나타내고 있어 자생적 기원보다는 육상기원에 의한 영향으로 생각되어진다.

• 한국대기환경학회지
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• 제10권3호
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• pp.191-196
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• 1994

Concentration of particulate nitrate originated from sea salt in ambient air was determined from February to October 1993. Sampling was carried out using a two-stage Anderson air sampler at the top of a five-story building located at Kon-Kuk University in Seoul. Concentration of NaNO$_3$, which originated from sea salt was highest in spring time and lowest in summer the and the concentration range was between 0.10 and 0.66 $\mu\textrm{g}$/㎥. NaNO$_3$/TSP ratio was very low 0.05~0.39%) indicating that the portion of NaNO$_3$ in TSP was negligible.

• 한국정밀공학회지
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• 제20권4호
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• pp.183-188
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• 2003

Particulate contamination is known to be a significant cause of failures of removable storage media. In this work, the effect of particles on the surface damage of removable hard disk media was investigated. The particles of different materials and size were introduced to the Head Disk Interface (HDI) using a particle injection system. It was round that the particles of particulate size and property serious damaged the media. This study showed that cleaning pad is effective for reducing particle contamination, except fer the particles of specific size and property. As a means to remove the particles of specific sire. the concept of using a stepped taper at the leading edge of the slider is proposed.

• 한국의류산업학회지
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• 제4권1호
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• pp.86-91
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• 2002

To estimate dispersion stability of particles, suspending power and particle size were examined as functions of pHs, surfactants, electrolytes and ionic strengths using ${\alpha}-Fe_2O_3$ particle as the model of particulate soil. Suspending power and particle size were determined by UV-Vis spectrumeter and by light scattering using the polarization ratio method, respectively. The suspending power was relatively high with polyanion electrolytes and was low with neutral salts. The suspending power was biphasis, minimum pH 6~7, and the effect of surfactant on the suspending power was insignificant. Generally suspending power increased with decreasing the particle size governed aggregation of dispersed particles regardless of solution conditions. Hence the suspending power was inversely related to the particle size.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.946-949
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• 2002

Particulate contamination is known to be a significant cause of failures of removable storage media. In this work, The effect of particles on the surface damage of removable hard disk media was investigated. The particles of different materials and size were introduced to the head-disk interface using a particle injection system. It was found that the particles of particulate size and property serious damaged the media. This study showed that cleaning pad is effective for reducing particle contamination, except for the particles of specific size and property. As a means to removed the particles of specific size, the concept of using a stepped taper at the leading edge of the slider is proposed.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.1-13
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• 1997

The key point that guarantees the durability of the ceramic monolith filter is to lower peak temperature and temperature gradient inside filter during regeneration. The control of the exhaust gas flow rate into the filter, by the bypass technique of the exhaust gas, enables the gas temperature in filter to be constant for regeneration. A couple of methods, which are the ON/OFF and PID control of the bypass valve, were used for feedback control of the gas temperature. These techniques showed that the ceramic filter was regenerated perfectly under the peak temperature and peak temperature gradient limitations for durability.