• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.97-100
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• 2005

The purpose of this study is to research the basic property of mortar as the grading distribution of copper slag used as fine aggregate and the results are as follows. The compressive strength of mortar as the size of largest diameter of copper slag granule is the highest when the largest size is in 2.5-5mm, and flow of mortar is in proportion to the size. As the largest size of copper slag particle is under 2.5mm(Type 1) the compressive strength and flow is higher as the big granules is more included than small ones. As the largest size of copper slag granule is under 5mm(Type 2) the compressive strength and flow is similar to situation of Type 1, except compressive strength is higher as the percent of the size of granule in $2.5\~5mm$ is under 35$\%$. F.M.(Fine Modulus), compressive strength and flow is relative each other except the batch with 2.5$\∼$5mm granule size of copper slag.

• Composites Research
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• 제13권4호
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• pp.19-32
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• 2000

본 논문은 강화입자가 균일하게 분산된 금속 복합재료의 제조와 반용융 성형을 위한 재가열에 관한 연구결과이다. 강화재 크기의 종류에 따른 금속복합재료를 제조하기 위하여 전자기식 교반과 기계식 교반을 동시에 이용한 복합 교반법을 사용하였다. 복합 교반법에 의하여 제조된 금속복합재료의 분산 상태를 조사하였다. 복합재료를 제조하기 위한 전자기식 교반법과 기계식 교반법을 겸용으로 한 공정이 소개되었다. 금속복합재료의 반용융성형을 위해서, 금속복합재료의 빌렛과 코일표면사이의 길이, 코일의 지름과 빌렛사이의 길이로 구성된 함수로 최적의 코일을 설계하여 빌렛을 재가열하였다. 복합재료의 반용융 성형시에 필요한 재가열 공정 인자인 가열시간과 온도변화의 관계를 조사하였다. 재가열중 강화재의 분산상태가 온도변화에 미치는 영향에 대하여 검토하였다.

• 약학회지
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• 제29권4호
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• pp.176-182
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• 1985

As a part of the studies on adsorptive properties of Korean halloysite clays, Hadong white clays of premium grade were examined for geometric pore structured by mercury porosimetry and for specific surface areas by nitrogen adsorption according to the BET procedure. Three size fractions of the native clay sample were derived from passage BS #100, #200 and #325 meshes, respectively. Several parameters lhus observed in relation to the pore structures are shown below: 1. The size fraction of BS #100, #200 and #325 show internal pore volumes of 25.3, 30.2 and $35.0m^2g^{-1}$, respectively. 2. In the distribution curves of the cumulative pore volume against pore diameter, it has been shown that the larticle sizes, the steeper the distribution over the larger ranges of pore diameters. The converse is true the smaller particles. 3. Internal pore areas increase with decrease in pore sizes. It follows that the pores having diameters of $\leq$0.1$\mu\textrm{m}$ are responsible for more than 90% of the total pore area. 4. The behaviour of nitrogen adsorption can be best described by BET type IV isotherm. Further, the hysteresis loops of the adsorptiondesorption curves become narrower with decresing particle sizes. 5. The specific surface areas observed for the fractions of BS #100, BS #200 and BS #325 are 34.6, 35.4 and 43.2m $^2g^{-1}$, respectively. and the calcined clay of BS #325 has a specific surface area near $30.4m^2g^{-1}$.

• Journal of Magnetics
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• 제18권3호
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• pp.311-316
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• 2013

Digital image processing has increasingly been implemented in nanostructural analysis and would be an ideal tool to characterize the morphology and position of self-assembled magnetic nanoparticles for high density recording. In this work, magnetic nanoparticles were synthesized by the modified polyol process using $Fe(acac)_3$ and $Pt(acac)_2$ as starting materials. Transmission electron microscope (TEM) images of as-synthesized products were inspected using an image processing procedure. Grayscale images ($800{\times}800$ pixels, 72 dot per inch) were converted to binary images by using Otsu's thresholding. Each particle was then detected by using the closing algorithm with disk structuring elements of 2 pixels, the Canny edge detection, and edge linking algorithm. Their centroid, diameter and area were subsequently evaluated. The degree of polydispersity of magnetic nanoparticles can then be compared using the size distribution from this image processing procedure.

• 폴리머
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• 제31권4호
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• pp.322-328
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• 2007

촉매인 potassium(K)을 2회 분할 투입하는 음이온 개환중합반응으로 ${\varepsilon}-caprolactam$을 분산매인 liquid paraffin 내에서 분간 중합하여 $4{\sim}7\;{\mu}m$의 직경을 가지는 단분산된 구형의 polyamide 6 (Nylon 6) micro-particle를 제조하였다. 융착 방지제의 농도, 촉매의 양, 개시제의 양에 따라 생성된 입자 크기, 형태, 그리고 분포의 변화를 비교 분석하였다. 그 결과 개시제인 $PCl_3$의 양이 단량체의 $0.97{\sim}1.17\;wt%$일 때 약 90.6%의 수율을 얻었으며, 또한 촉매를 $1.3{\sim}1.4\;wt%$ 정도로 투입하였을 경우 가장 안정된 구형의 미세입자가 제조되고 높은 수율이 얻어짐을 알 수 있었다.

• 한국응용과학기술학회지
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• 제30권4호
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• pp.602-611
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• 2013

We have investigated the influence of system composition and preparation conditions on the particle size of vitamin E acetate (VE)-loaded nanoemulsions prepared by PIC(phase inversion composition) emulsification. This method relies on the formation of very fine oil droplets when water is added to oil/surfactant mixture. The oil-to-emulsion ratio content was kept constant (5 wt.%) while the surfactant-to-oil ratio (%SOR) was varied from 50 to 200 %. Oil phase composition (vitamin E to medium chain ester ratio, %VOR) had an effect on particle size, with the smallest droplets being formed below 60 % of VOR. Food-grade non-ionic surfactants (Tween 80 and Span 80) were used as an emulsifier. The effect of f on the droplet size distribution has been studied. In our system, the droplet volume fraction, given by the oil volume fraction plus the surfactant volume fraction, was varied from 0.1 to 0.3. The droplet diameter remains less than 350 nm when O/S is fixed at 1:1. The droplet size increases gradually as the increasing the volume fraction. Particle size could also be reduced by increasing the temperature when water was added to oil/surfactant mixture. By optimizing system composition and homogenization conditions we were able to form VE-loaded nanoemulsions with small mean droplet diameters (d < 50 nm). The PIC emulsification method therefore has great potential for forming nanoemulsion-based delivery systems for food, personal care, and pharmaceutical applications.

• 한국대기환경학회지
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• 제33권4호
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• pp.361-369
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• 2017

In this study, the characteristics of the dust emission according to the presence or absence of operation of the gas stove were analyzed by particle size analysis and density estimation while the mackerel was cooked while the fan was placed on the gas stove used in the home. The experiment was carried out using 20 mackerel of normal size at home. Commercially available canola oil was used as edible oil. In order to understand the characteristics such as particle size distribution of fine dust, light scattering measurement method which can be measured at intervals of several seconds was used. Particles generated by combustion of gas stove, particles formed by heating cooking oil, and particles generated by heating mackerel fish meat are judged to be nano size particles smaller than $1{\mu}m$. Therefore, it is necessary to use precise measurement method rather than the measurement method using the filter which is currently being measured in the measurement of the particles discharged from the fuel combustion or food cooking in the future. Analyzing the particle size and density of the dust emitted from the cooking stove is expected to contribute technically to the reduction of dust emissions from the cooking process of gas and fuel facilities at home and commercial facilities.

• 농업과학연구
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• 제48권4호
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• pp.843-853
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• 2021

The objectives of this paper were to simply estimate soil loss levels as caused by wind in reclaimed tidal flat land (RTFL) and the threshold wind velocity in the RTFL. For this experiment, RTFL located at Haenam Bay was selected and a total of 150 soil samples were collected at the Ap horizon from the five soil series. The particle distribution curves, including the limit of the non-erodible particle size (D > 0.84 mm) for each Ap horizon soil, show that the proportions of non-erodible particle sizes that exceeded 0.84 mm were 4.3% (Taehan, TH), 8.9% (Geangpo, GP), 0.5% (Bokchun, BC), 1.6% (Poseung, PS) and 1.4% (Junbook, JB), indicating that the amount of non-erodible soil particles increased with an increase in the sand content. The average monthly, daily and instantaneous wind velocities were higher than the threshold friction velocity (TFV) calculated according to the dynamic velocity (V_d) by Bagnold, while the average monthly wind velocity was lower than those of the TFV suggested by the revised wind erosion equation (RWEQ) and wind erosion prediction system (WEPS). The susceptible proportions of erodible soil particles from the Ap horizon soil samples from each soil series could be significantly influenced by the proportion of sand particles between 0.025 and 0.5 mm (or 0.84 mm) in diameter regardless of the threshold wind velocity. Thus, further investigations are needed to estimate more precisely soil erosion in RTFL, which shows various soil characteristics, as these estimations of soil loss in the five soil series were obtained only when considering wind velocities and soil textures.

• Journal of Forest and Environmental Science
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• 제37권3호
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• pp.193-205
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• 2021

The importance of forests and trees in climate change mitigation and soil nutrient cycling cannot be overemphasized. This study assessed the above-ground carbon stock of two exotic and two indigenous tree species - Gmelina arborea, Tectona grandis, Khaya grandifoliola and Nauclea diderrichii and their litter impact on soil nutrient content of an arboretum within the University of Port Harcourt, Nigeria. Data were collected from equal sample plots from the four species' compartments. Tree growth variables including total height, diameter at breast height, crown height, crown diameter and merchantable height were measured for the estimation of above-ground carbon stock. Soil samples were collected from a depth of 0-30 cm from each compartment and analyzed for particle size distribution, organic carbon, total nitrogen, available phosphorus, exchangeable bases, exchangeable acidity, cation exchange capacity, base saturation, pH, Manganese, Iron, Copper and Zinc. Analysis of Variance (ANOVA) was used to test for significant difference (p<0.05) in the carbon contents of the four species and the soil nutrient contents of the different species' compartments. Pearson correlation was used to assess the relationships between the carbon contents, growth parameters and soil parameters. The highest and lowest carbon stock per hectare was observed for G. arborea (151.52 t.ha^-1) and K. grandifoliola (45.45 t.ha^-1) respectively. Cation exchange capacity and base saturation were highest and lowest for soil under G. arborea and K. grandifoliola respectively. The pH was highest and lowest for soil under G. arborea and T. grandis respectively. Carbon stock correlated positively with dbh, crown diameter, merchantable height and Zn and negatively with base saturation. The study revealed that G. arborea and N. diderrichii can effectively be used for reforestation and afforestation programmes aimed at climate change mitigation across Nigeria. Therefore, policies to encourage and enhance their planting should be encouraged.

• Korean Chemical Engineering Research
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• 제43권5호
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• pp.609-615
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• 2005

$1{\mu}l$ 정도의 미량 titanium tetraisopropoxide(TTIP)를 주사기를 사용하여 1 cc 부피의 증발관에 주입하여 기화시킨 후 질소에 의해 직경 4 mm, 길이 35 cm의 관형 에어로졸반응기로 운반하여 열분해 시킴으로써 30-300 nm 크기의 $TiO_2$ 나노입자를 제조하였으며, 반응온도 및 TTIP 증기 농도가 생성된 $TiO_2$ 입자의 형상, 크기, 결정성 등에 미치는 영향을 조사하였다. 전구체 증기 농도 1 mol%에서 반응온도를 300, 500, $700^{\circ}C$로 변화시킨 결과 반응온도가 증가함에 따라 응집체를 구성하고 있는 1차 입자 크기가 감소하였고, $700^{\circ}C$에서는 입자 크기분포가 bimodal 형태를 나타내었다. 반응온도를 $700^{\circ}C$로 유지하고 전구체 증기 농도를 1, 3.5, 7 mol%로 변화시킨 결과 전구체 증기 농도 3.5 mol% 이상에서는 1 mol%에서 관찰되었던 bimodal 분포가 사라지고 응집체 내 1차 입자들의 개수가 상대적으로 많이 증가하였다. 반응온도 및 전구체 농도가 입자의 형상, 크기분포에 미치는 이와 같은 영향들을 이전의 연구결과들과 함께 비교 분석하였다.