• 한국분무공학회지
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• 제3권3호
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• pp.14-22
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• 1998

The growth by steam condensation of an hygroscopic aerosol is investigated using the condensation rate model which has been derived from the mass and heat transfer equations. The present model accounts for both the solute and Kelvin effects. When the hygroscopicity is considered, condensation can occur on hygroscopic seed particles even under subsaturated steam conditions. This study focuses on the effect of hygroscopicity on the evolution of the particle size distribution and decay of the total aerosol concentration. It is found that hygroscopicity causes the particle size distribution to rapidly move upward even in a very short time, resulting in substantially higher decay of the total aerosol concentration than the case without considering hygroscopicity.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.664-667
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• 2001

Segregation of binary particle systems in a horizontally gyrated bed has been experimentally studied to recover the heavy metals from municipal waste incineration (MWI) ash. Differences in density and size had less effect on segregation. Effective segregation took place under the centrifugal effect of 1 or less for any particle size ratio. Zn, Cu and Pb were concentrated in the upper side of bed by the horizontal vibration. However, there was less change in concentration for other metals such as Mg, Al and Fe etc. The separation system with the horizontal gyrating separator proved to be an effective method for the pretreatment of recovering Zn, Cu and Pb from incineration residues.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.99-106
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• 2010

A piezo-driven injector was applied with a purpose to evaluate the effect of induced voltage on spray characteristics. For this, injection rate, macroscopic imaging, ambient gas entrainment and particle sizing were carried out. It was shown that initial slope of injection rate was steeper as induced voltage increased, while slope of injection rate became mostly constant with fully opened needle. From macroscopoic imaging, longer spray tip penetration was produced with higher induced voltage. Moreover, wider spray angle was detected in the early stage of spray development, when higher induced voltage was applied. Ambient air entrainment rate was increased and particle size was reduced with higher induced voltage.

• 한국세라믹학회지
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• 제42권11호
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• pp.743-748
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• 2005

The effect of reaction parameters in the characteristic of $Pb(Zr_{0.52} Ti_{0.48})O_3$ powders by hydrothermal process was investigated in this study. In the preparation of PZT, the types of starting material and concentration of mineralizer on phase fraction and morphology was investigated respectively. Regardless the types of Pb precursor, PZT was able to synthesize ranging from 7 to 20 on KOH concentration and from 13.01 to 13.55 on pH of solution. The particle size of the PZT powders can be controlled by the mineralizer concentration and various types of precursor.

• 대한화학회지
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• 제7권2호
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• pp.144-152
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• 1963

브리스톨釉藥을 콘 5, 8, 11 番으로 燒成했을때 나타나는 狀態에 對한 組成變化와 粒度의 京鄕을 硏究하여, 밝은 半艶消 또는 艶消釉藥을 얻을 수 있었다. 卽 各 釉藥에 對한 熱成範圍, 曲强度 및 光澤, 平滑性, 乳白度, Eggshelling, 龜裂, Pinholing, Crawling 等에 對한 因子를 決定하므로서 얼마나, 珪酸, 알카리, 石灰를 變化시켜 實際 使用可能한 良好한 釉藥을 얻었다. 製造된 브리스톨釉藥은 最低 콘 5番부터 11번 또는 그 以上에서 긴 熟成範圍를 나타냈다. Crawling의 傾向에 있어서는 ZnO 量이 增加될때 特히 甚했으나, $Al_2O_4:\;SiO_2$의 比가 크고 ZnO 量이 많을때 乳白度가 顯著하였다. 釉藥의 粒子를 가늘게 하면 熱成이 잘되나 微粒이면 Crawling이 커진다. 釉藥두께를 增加해도 Crawling 傾向이 커진다.

• 한국식품저장유통학회지
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• 제24권7호
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• pp.965-974
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• 2017

본 연구에서는 영양학적 가치가 높은 쌀귀리의 식품산업 이용률을 높이고자 쌀귀리를 입도별로 제조하여 이들의 이화학적 특성 및 항산화 활성을 비교하였다. 쌀귀리의 조단백질, 조지방 및 조회분 함량이 각각 15.7%, 10.0% 및 1.8%이었으며, 입도가 작아질수록 이들의 함량은 감소하였다. 주요 유리아미노산은 비필수아미노산 중에서는 cystine(58.3 mg%), ${\beta}$-aminoisobutyric acid(53.8 mg%) 등, 필수아미노산 중에서는 phenylalanine(8.6 mg%)과 histidine (12.2 mg%)이었으며, 입도가 작아질수록 함량은 감소하였다. 총 전분, 아밀로스, 손상전분, 총 식이섬유, ${\beta}$-glucan 및 총 유리당 함량은 각각 56.4%, 21.4%, 11.7%, 11.0%, 4.7% 및 2,555.3 mg%이었으며, 입도가 작아질수록 총 전분, 아밀로스 및 손상전분의 함량은 감소한 반면에 총 식이섬유와 ${\beta}$-glucan의 함량은 증가하였다. 색도는 L 값이 75.3, a 값이 0.3 및 b 값이 13.1이었으며, 입도가 작아질수록 L 값은 증가하였으나 a와 b 값은 감소하였다. 호화특성은 최고점도가 263.8 RVU, 최저점도가 155.6 RVU 및 최종점도가 399.3 RVU이었으며, 입도가 작아질수록 최고점도와 최종점도는 증가하였다. TPC, TFC 및 항산화 활성(DPPH radical assay, ABTS radical cation assay 및 reducing power)은 각각 $237.8{\mu}g/g$, $90.9{\mu}g/g$, 57.3%, 53.4% 및 0.23이었으며, 입도가 작아질수록 항산화 성분 및 항산화 활성은 감소하였다. 한편 TPC와 TFC에 관한 각 항산화 활성의 결정계수(correlation determination coefficient, $R^2$) 값이 각각 0.87 이상과 0.81 이상으로 나타나 항산화 성분과 항산화 활성은 상관성을 보였다.

• 대한기계학회논문집B
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• 제25권3호
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• pp.315-321
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• 2001

Aerodynamic lenses are widely used in generating particle beams of high density and small diameter, but analytical or modeling studies are limited only in the free molecular regime. In this study, it is shown that generating particle beam is also possible in atmospheric pressure range, and the mechanism of generating particle beam using an orifice is analysed into three different parts : fluid dynamic contraction, diffusional defocusing, and inertial focusing. In laminar flow conditions, the diffusional defocusing effect can be neglected, and the effects of inertial focusing can be expressed in terms of the orifice size and Stokes number. Numerical experiments are done for two different orifices, d/D=1/5 and 1/10 and particle diameter d(sub)p=1-10 ㎛. The results for two different orifices can be made into a single curve when a modified Stokes number is used. The inertial focusing effect diminishes when the modified Stokes number becomes smaller than 10(sup)-2.

• Geomechanics and Engineering
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• 제21권4호
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• pp.315-326
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• 2020

The long-term behavior of rockfill material used in the construction of infrastructures such as dams is of great significance. Because of concerns about the application of weak rockfill material in dam construction, further experimental studies on the behavior of these materials are required. In this study, laboratory experiments were performed to investigate the one-dimensional deformation and particle breakage of the weak rockfill material under stress. A one-dimensional compression apparatus was designed and developed for testing of rockfill materials of different maximum particle sizes (MPSs). The compression tests were performed under dry, wet and saturated conditions on samples of rockfill material obtained from a dam construction site in Iran. The results of the experiments conducted at the specimen preparation stage and the 1D compression tests are presented. In weak rockfill, the effect of the addition of water on the behavior of the material was uncertain as there were both an increases and decreases observed in particle breakage. Increasing the MPS of the weak rockfill materials increased particle breakage, which was similar to the behavior of strong rockfill material. In all of the MPSs examined, the settlement of specimens under wet conditions was higher than that observed under dry conditions. Also, the greatest deformation occurred during the first hour of loading.

• Preventive Nutrition and Food Science
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• 제16권2호
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• pp.174-178
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• 2011

The cell permeability and cytotoxic effects of different-sized zinc oxide (ZnO) particles were investigated using a human colorectal adenocarcinoma cell line called Caco-2. Morphological observation by scanning electron microscopy revealed that three zinc oxides with different mean particle sizes (ZnO-1, 20 nm; ZnO-2, 90~200 nm; ZnO-3, $1\sim5\;{\mu}m$) tended to aggregate, particularly in the case of ZnO-1. When cytotoxicities of all three sizes of zinc oxide particles were measured at concentration ranges of $1\sim1000\;{\mu}g$/mL, significant decreases in cell viability were observed at concentrations of $50\;{\mu}g$/mL and higher. Among the three zinc oxides, ZnO-1 showed the lowest viability at $50\;{\mu}g$/mL in Caco-2 cells, followed by ZnO-2 and ZnO-3. The permeate concentration of ZnO-1 from the apical to the basolateral side in the Caco-2 model system after four hours was about three-fold higher than that of either ZnO-2 or ZnO-3. These results demonstrated that ZnO-1, with a 20 nm mean particle size, had poorer viability and better permeability in Caco-2 cells than ZnO-2 and ZnO-3.

• 대한기계학회논문집B
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• 제38권12호
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• pp.963-969
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• 2014

본 연구는 고회분탄의 최적화된 연소 조건을 알아보기 위해 회분 함량이 각기 다른 네 종류 석탄의 연소시 배출되는 NOx및 미연분 특성을 알아보았다. 실험은 DTF(Drop Tube Furnace)를 통해서 다양한 입자크기조건 및 공기다단방식을 도입하여 수행하였다. 결과로 회분의 함량이 증가할수록 미연분이 증가하며, 입자크기가 증대될수록 미연분에 대한 회분의 영향이 명확해짐을 확인하였다. 또한, 회분의 함량이 증가할수록 Char-NOx가 감소하며, 입자크기가 감소할수록 NOx의 배출이 감소하는 것을 확인하였다. 본 연구는 고회분탄의 NOx를 저감하는 방법으로 공기다단방식의 적용을 제안하며 전단 연소 영역의 공기과잉률 변화를 통한 최적화된 연소조건을 제시하였다.