• Polymer(Korea)
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• v.35 no.3
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• pp.254-259
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• 2011

In electrospraying of polymer solutions, metal sample collectors are often ineffective in fully removing solvent from sprayed particles and recovering redispersable sprayed particles. Herein, a novel electro spraying system, where sprayed particles were dispersed into laminar flow of dispersant (coagulation liquid), was designed for the nano-encapsulation of protein drugs. Chitosan and polyacrylic acid were used as the encapsulation materials. Aggregation of particles could be prevented by using this new electrospraying system, and unimodal size distribution was observed at an applied voltage between 4~16 kV and a low flow rate. The effects of the applied voltage on mean particle size were not significant on the other hand.

• Food Science and Preservation
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• v.22 no.3
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• pp.392-398
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• 2015

The physicochemical properties of spray-dried rice flour with Lactobacillus plantarum CGKW3 were investigated. Amylose and damaged starch contents of spray-dried rice flour (S10, S20, S30, and S50) with L. plantarum CGKW3 were 14.18~17.75% and 24.65~34.08%, respectively. The particle size of spray-dried rice flour was $82.28{\sim}131.17{\mu}m$. The rice flour with L. plantarum CGKW3 showed a good powder flowability. The water absorption and water solubility of spray-dried rice flour were 1.96~2.13 and 9.91~21.95%, respectively. Thermal properties measured by differential scanning calorimeter revealed that the enthalpy (${\Delta}H$) for starch gelatinization were highest in the rice flour (S50) with L. plantarum CGKW3. When compared, the viable cell number of spray-dried rice flour were found to be in the following order: S10 (5.78 log CFU/g) < S20 (6.38 log CFU/g) < S30 (6.69 log CFU/g) < S50 (7.11 log CFU/g). The survaival rate of L. plantarum CGKW3 was 60.02-73.85%, which reflected the improvement in the quality of rice flour with an increase in treatment concentration. Based on our results, spray-dried rice flour with L. plantarum CGKW3 could be used in various types of rice foods.

• Journal of Korea Water Resources Association
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• v.50 no.3
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• pp.201-210
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• 2017

This study proposes a numerical model which is able to simulate turbidity currents intruding into a reservoir and resulting sediment depositions. The proposed model is applied to laboratory experiments by Toniolo and Schultz (2005), and propagation of turbidity currents, morphological change, and trap of suspended sediment are simulated. It is simulated that the turbidity current after plunging at the foreset of the model delta, propagates along the bottom. The thickness of the turbidity current increases significantly after being blocked by the dam, and this effect is propagated in the upstream direction. In addition, it is simulated that the foreset moves in the downstream direction due to both the bedload and suspended load and the thickness of the bottom set increases due to the suspended load. It is found that the height of the intake affects the thickness of the turbidity current and the location of the internal hydraulic jump. The impact of the height of the intake on the trap efficiency is not clear in the experimental results, however, overall trap efficiency is predicted quite successfully by the model. Also, sensitivity analysis is carried out, and the results indicates that the particle size affects the trap efficiency most.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.121-127
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• 2010

The in-furnace desulfurization technique is applied to the $O_2/CO_2$ combustion system for the carbon capture and storage (CCS) process because this combustion system does not need an additional chamber for the desulfurization. $CaCO_3$ sorbent particles, which have a wide range in size from a few nanometers to several tens of micrometers, are used for this process. In this study, an experimental system which can simulate the $O_2/CO_2$ combustion system was developed. $CaCO_3$ sorbent particles were exposed to the high temperature reactor at $1200^{\circ}C$ with various residence times (0.33-1.46 s) in air and $CO_2$ atmospheric conditions, respectively. The sorbent particles were then sampled at the inlet and outlet of the reactor and analyzed qualitatively/quantitatively using SMPS, XRD, TGA, and SEM. The results showed that the residence time and atmospheric condition in a high temperature reactor can affect the characteristics of the $CaCO_3$ sorbent particles used in the in-furnace desulfurization technique, such as the calcination rate and reaction mechanism.

• Journal of the Mineralogical Society of Korea
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• v.29 no.2
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• pp.79-87
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• 2016

Asian dust (Hwangsa) interacts with light, atmospheric gas, aerosol, and marine ecosystem, affecting Earth climate. Mineralogical properties are essential to understand the interaction between the dust and environments. In this study, we examined the mineralogical properties of Asian dust collected at Deokjeok Island, Incheon, Korea in February 22, 2015. X-ray diffraction (XRD) analyses showed that phyllosilicate minerals (62 wt%) dominate the Asian dust. Illite-smectite series clay minerals (55%) were common with minor chlorite (5%) and kaolinite (2%). Non-phyllosilicate minerals were quartz (18%), plagioclase (10%), K-feldspar (4%), calcite (4%), and gypsum (1%). Similar results were obtained by mineral quantification using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Transmission electron microscopy combined with EDS confirmed illite-smectite series clay minerals as the dominant phyllosilicate type. Morphological analyses using SEM showed clay agglomerates, clay-coated quartz, feldspars, and micas. Gypsum grains were common on the particle surface, while calcite nanofibers, previously reported as common on the surface, were rare, indicating the reaction of calcite and acidic atmospheric pollutants to form gypsum. The analytical result of 2015 Asian dust would contribute to the establishment of mineralogical base for the modeling of the interaction between Asian dust and environments.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.461-468
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• 2019

Demand for improving dust removal efficiency in coal power plants and the dust removal requirement to the level of capturing fine particulate matter and ultrafine particles have been increasing. While bag filter and electrostatic precipitator (ESP) are typically used for dust removal in the processes operating at atmospheric pressure, metal filters or ceramic filters are employed for dust which is produced at high temperature/pressure system as in coal gasification. For dust removal at the high temperature/pressure conditions, two metal filters of five compressed/sintered layers were manufactured and applied to analyze the dust removal characteristics. Manufactured metal filters exhibited more than 99% dust removal efficiency on coal gasification fine particulates in mass basis. To evaluate the fine particulate removal efficiency of less than $2.5{\mu}m$, JIS standard fine sample was used and confirmed the removal efficiencies of 97% and 70~82% on the fine particulates of $1{\sim}2.5{\mu}m$ size range. For the size range of less than $1{\mu}m$, dust removal efficiency of manufactured metal filters significantly degraded with smaller particle size. Improving methods are proposed to overcome the limitations in applying to fine dust of less than $1{\mu}m$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.3
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• pp.217-226
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• 2006

The structural and contamination characteristics of hot cells at KAERI were investigated. The SEM results showed that the size of the hot particulate on the inner surface of the hot cell ranged from 0.2 to $10{\mu}m$. It was found that an inlet flow rate of 15 m/sec was suitable for this developed cyclone with a 49 mm optimum vortex finder length. The results showed that the collection efficiency was about 85% for $3{\mu}m$ particles. The collection efficiency didn't show a sharp increase when the inlet flow rate was faster than 15m/sec. When the temperature of the inlet flow gas was increased, the collection efficiency of the cyclone was slightly decreased. The larger the vortex finder length was, the higher the pressure drop in the cyclone was. The cut size diameter decreased with an increment of the Reynolds number. It was established that the flow in the cyclone was a turbulent flow on the basis of the Reynolds number and this turbulent flow caused a pressure drop in the cyclone. $Stk^{1/2}_{50}$ decreased with increasing values of the Reynolds number and it gradually approached a constant value at a higher value of the Reynolds number Namely, $Stk^{1/2}_{50}$ approached approximately 0.045 between 6000 and 8000 of the Reynolds number.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.639-644
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• 2013

In this study, ethosomes loaded with Eucommia ulmoides extracts that have anti-inflammatory and anti-aging activities on the skin were prepared as cosmetic materials. The particle size, physical property, and entrapment efficiency of ethosomes to identify their stabilities during 4 weeks were measured. Ethosomes containing 0.01~0.05% E. ulmoides extracts did not show either precipitation or separation. The mean particle size of these ethosomes was 136.4 nm, and monodisperse. The particle size of ethosome containing 0.05% E. ulmoides extracts was 151.15 nm and the entrapment efficiency was 81.79%. Therefore, in vitro skin permeation experiment was performed with ethosome containing 0.05% E. ulmoides extracts that showed the high loading efficiency and stability during 4 weeks. The order of skin permeation of E. ulmoides extracts was ethosome (77.16%) > liposome (62.80%) > ethanolic solutoin (41.59%). These results suggest that ethosomes containing 0.05% E. ulmoides extracts are effective for the skin permeation and may be used as a cosmetic formulation containing plant extracts.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.37-45
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• 2015

Prediction of combustion instability within a solid-propellant rocket motor has been conducted with the classical acoustic analysis. The effect of particle size distribution on the instability has been analyzed by comparing the log-normal distribution to the fixed mono-sized particle followed by a survey of motor length scale effect between the baseline model and small scale model. Particle damping effect was more efficient for the small scale motor which has a relatively high unstable mode frequencies. It was also revealed that the prediction results by considering the particle size distribution show an overall attenuation of fluctuating pressure amplitude with respect to the mono-sized case.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.397-398
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• 2003

대기 중 분진을 제거하는 방식으로 여과 이론을 적용할 수 있는 경우는 섬유 여과기, 입자상 여과기, 액적에 의한 습식 세정기 그리고 기포를 이용한 분진 제거 방법 등을 들 수 있다. 이러한 여과 원리를 이용한 집진 설비를 설계하는데 있어, 액적 또는 기포 주위의 유동장을 정확히 파악하는 것은 매우 중요하다. 특히, 포집구의 크기가 작아지고 화학적으로 반응성을 갖는 고온의 함진가스가 유입되는 경우 및 저압에서 운영되는 경우에 누드센수(Knudsen number)의 영향을 무시할 수 없는데 이러한 영역을 저 누드센 영역(low Kundsen number regime)이라고 한다(Lee et al., 1978). (중략)