• 한국식품과학회지
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• 제22권4호
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• pp.369-372
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• 1990

두유에는 기름의 양이나 입도를 분석하는데 장해를 주는 대두단백질, 미세한 대두입자들이 공존하고 있어서 기존의 microscopic image analysis, coulter counter, 또는 Photo-analysis 등의 사용이 많은 문제점을 노출했다. 본 실험에서 Stokes 법칙을 응용하여, 중력장과 원심력장하에서 homogeneous suspension과 cumulative method를 이용하여 입도분포를 분석했다. 선정된 두유에서 기하학적 평균지름은 중력장하에서는 $0.33{\mu}m$ 표준편차 $1.73{\mu}m$이고, 원심력 장에서는 평균지름은 $0.31{\mu}m$, 표준편차는 $1.81{\mu}m$으로, 매우 유사한 결과를 얻었다. 균질압이 유화안정성에 크게 영향을 주는 인자이기 때문에 균질압을 변화했을 때, 균질압이 높을수록 평균입도는 작은 쪽으로 이동하였으며, 입자의 분산 형태는 평균지름을 중심으로 밀도 있게 분포하는 쪽으로 변화하여, 균질압이 기름 입도분포에 영향을 미쳐 유화 안정과 깊은 관계가 있는 것을 확인하였다.

• 한국분말재료학회지
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• 제28권2호
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• pp.120-126
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• 2021

In this study, AlSi10Mg alloy powders are synthesized using gas atomization and sieving processes for powder bed fusion (PBF) additive manufacturing. The effect of nozzle diameter (ø = 4.0, 4.5, 5.0 and 8.0 mm) on the gas atomization and sieving size on the properties of the prepared powder are investigated. As the nozzle diameter decreases, the size of the manufactured powder decreases, and the uniformity of the particle size distribution improves. Therefore, the ø 4.0 mm nozzle diameter yields powder with superior properties. Spherically shaped powders can be prepared at a scale suitable for the PBF process with a particle size distribution of 10-45 ㎛. The Hausner ratio value of the powder is measured to be 1.24. In addition, the yield fraction of the powder prepared in this study is 26.6%, which is higher than the previously reported value of 10-15%. These results indicate that the nozzle diameter and the post-sieve process simultaneously influence the shape of the prepared powder as well as the satellite powder on its surface.

• 대한기계학회논문집
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• 제15권6호
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• pp.2147-2159
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• 1991

본 연구에서는 가장 다순한 내부혼합형 이류체분사노즐의 기류속도, 액체유량, 노즐직경 및 혼합길이, 기액접촉각을 변화시켜 평균입경(SMD), 분무각, 입도분포, 분 무분사량분포 등을 조사하여 노즐형상에 따른 분무특성의 변화를 자세히 밝혀, 분무특 성을 조절할 수 있는 이류체분사 노즐의 설계에 대한 기초적 자료를 제시하고자 한다.

• 한국분무공학회지
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• 제19권4호
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• pp.197-203
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• 2014

The liquid jet breakup has been studied in the areas such as aerosols, spray and combustion. The breakup depends on several physical parameters such as the jet velocity, the nozzle inner diameter, and the density ratio of the water to the jet. This paper deals with characteristics of the jet breakup according to the jet velocity and the nozzle diameter. In order to consider only hydrodynamic factors, all the experiments were conducted in non-boiling conditions. The jet behavior in the water pool was observed by high-speed camera and PIV technique. For the condition of the inner diameter of 6.95 mm and the jet velocity of 2.8 m/s, the debris size of 22 mm gave the largest mass fraction, 39%. For higher jet velocity of 3.1 m/s, the debris size of 14 mm gave the largest mass fraction, 36%. For the nozzle with inner diameter of 9.30 mm, the debris size distribution was different. For jet velocity of 2.8 m/s and 3.1 m/s, the debris size with the largest mass fraction was found to be 14 mm. It was identified that the debris size decreased as the diameter or the jet velocity increased.

• 한국자원식물학회지
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• 제12권4호
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• pp.297-302
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• 1999

화훼용 작약 품종육성의 기초자료로 활용하고자 작약 혼계집단내에서 화형의 특성 및 분포를 조사하였다. 개화기의 분포는 중간형이 56%로 가장 많았고, 빠른 것은 18%, 늦은 것은 26%였으며 개화지속기간은 8일 이하가9%, 9∼11일이 50%, 12∼14일이 37% 그리고 15일 이상은 4%였다. 꽃의 크기는 중간형 크기가 65%로 가장 많았으며 대형은 24%, 소형은 11%였고, 화색은 6가지로 분포하였으나 분홍이 56%로 가장 많았으며 붉은색과 횐색은 각각 8%, 2%였다. 화기는 암술에 있어서 많은 것이 26%였으나 전혀없는 것은 4%였으며, 수술은 많은 것이 77%로 대부분이었으나 전혀 없는 것도 19%나 되었다. 화형은 single형이 76%로서 대부분을 차지하였고 anemone, crown, bomb, japanese형 등이 분포하였다. 화경직경은 꽃크기 및 수술수, 수술수는 암술수와 고도의정의상관이 그리고 수술수와 꽃잎수, 수술수와 꽃잎수와는 부의상관이 있었다.

• 한국입자에어로졸학회지
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• 제16권1호
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• pp.9-17
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• 2020

The characteristics of particulate matter made from daily cooking at a Korean residential apartment house with three dwellers had been investigated for about 3 months. All data were recorded by an optical particle counter every minute at the kitchen. Types of cooking such as boiling, frying, and grilling that performed in the house were listed. Boiling only was used in 32% cases among total 234 meals. Frying and grilling were 14% and 11%, respectively. From an initial indoor particulate matter smaller than 10 ㎛ in diameter, the increases due to cooking are reported by size. In case of boiling, PM at 1-10 ㎛ size and under 1 ㎛ size little increased. Normally, particles from oil or combustion in a process of frying or grilling increased indoor PM. In a case of grilling, particle mass concentration in a region of 1-10 ㎛ in diameter increased as much as 295 ㎍/㎥. Mass concentration of particles smaller than 1 ㎛ increased as much as 33 ㎍/㎥.

• Elastomers and Composites
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• 제55권1호
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• pp.20-25
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• 2020

The effect of the isocyanate index (NCO index) on the particle size and particle size distribution of a waterborne polyurethane dispersion (WPUD) with polycarbonate-diol was determined. The WPUDs were prepared using a conventional acetone process with polycarbonate-polyol (M_n = 2028), 4,4'-methylenebis(cyclohexyl isocyanate) (H₁₂MDI), 2,2-bis(hydroxymethyl) propionic acid (DMPA), and dibutyltin dilaurate catalyst. At NCO index values below 1.5, the number average particle diameter of the WPUDs significantly increased with the NCO index, whereas the particle diameter slightly varied at higher NCO indexes. The dependency of the WPUD viscosity on the NCO index exhibited similar behavior to that of the particle size. The relative values of the full width at half maximum of the WPUD particle distribution curves at various NCO indexes were not influenced by the NCO index.

• Journal of information and communication convergence engineering
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• 제4권1호
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• pp.46-52
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• 2006

Precipitation measurement with ground-based radar needs an information of the raindrop size distribution (RSD) characteristics. A 10-month dataset was collected in tropical Atlantic coastal zone of northeastern Brazil where the weather radar was installed. The number of drop was mainly recorded in 300 - 500 drop $mm^{-3}$, of which the maximum was registered around 1.1 mm drop diameter.

• 한국분무공학회지
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• 제1권3호
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• pp.51-59
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• 1996

An experiment was carried out on the structure of twin spray from pressurize-swirl nozzles, in order to investigate the effect of different size of spray nozzles on the characteristics of the overlap of two single sprays, for example, mean diameter, number density, and spatial distribution of flow rate. Using image processing method, the distributions of size and velocity of droplets of a single spray and twin spray were measured and compared to investigate the overlapping effect of two identical sprays. Comparing experimental results from a twin-spray with those from two-single sprays shows that the flow rate distribution of the twin-spray was concentrated around the midst of the overlapping region of two sprays. In this region, Sauter mean diameter (SMD) did not change much in the twin spray from 6032 nozzles, but it was smaller by 10 micrometers in the twin-spray than two-single sprays from 60063 nozzles. In spite of large difference in Weber numbers of the colliding sprays between the 60063 and 6032 nozzles, the phenomena did not have a big change in the overlapping region of twin spray. This shows that in the collision between droplets from two single spray in the overlapping region to cause the disruption of droplets, the size distribution of spray droplets was also important as well as Weber number.

• 한국대기환경학회지
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• 제2권2호
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• pp.60-65
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• 1986

Atmospheric particulates were collected at a site near the front gate of the Yonsei University using nine stages Andersen air sampler and the distribution of seasonal particle size was investigated. Rubber, Pb and Zn contents of the collected particulates in each stage were determined. Particle size distribution of atmospheric particulate, which was made by concentration distribution curve method, was usually divided into two groups, course (particles larger than 1 - 2 $\mu m in diameter$) and fine (particles smaller than 1 - 2 \mu m in diameter$) groups, regardless of sampling period. More than 80 percent of the total rubber contents in atmospheric particulates were larger than $5 \mu m$ in diameter, meaning that most of rubber particles were originated from tire tread. After benzene extraction for 4 hrs, the extracts were analyzed by Curie-point pyrolysis gas chromatography for rubber content. Pb and Zn contents were determined by atomic absorption spectroscopy. The annual average concentration of rubber particles was $4.2 \mu g/m^3$, which corresponded to 2.2% of the annual average total suspended particulates. Average concentration of styrene brtadiene rubber was about five times that of natural rubber. Annual average concentrations of Pb and Zn were $1.2 \mu g/m^3 and 0.4 \mu g/m^3$ respectively, which corresponded to about 0.7% and 0.2% of the annual average total suspended particulates.