• Journal of the Korean Magnetics Society
• /
• v.16 no.1
• /
• pp.107-110
• /
• 2006

Magnetite nanoparticles encapsulated with biodegradable polymer [poly(D,L-lactide-co-glycoiide), PLGA] were prepared by an emulsification-diffusion method. To investigate the effect of type of organic solvents on the mean particle sizes of obtained composite particles, different organic solvents [ethyl acetate (EA), propylene carbonate (PC) and acetone (ACE)] were used with a stabilizer [didodecyl dimethyl ammonium bromide (DMAB)]. The particle size of nanoparticles was observed by the dynamic light scattering method. When EA and PC as partially water-soluble solvents were used, small composite nanoparticles below 80nm were obtained, while large composite nanoparticles above 330nm were prepared for ACE as a fully water-soluble solvent.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.5
• /
• pp.15-23
• /
• 2010

Dry sieving, wet sieving and photoscattering analyzer were tested as particle size analyzing methods for sediments from rivers and lakes of Han river, Nakdong river, Youngsan river, and Kumgang river area. Dry sieving showed a big error due to coagulating effect over drying process and this phenomena was severe for lake sediment. Wet sieving and PSA showed an accurate results though wet sieving needs more labor and complicate processes. Freeze-dry or freeze-dry after oxidation of organics with hydrogen peroxide showed improved results but gave lower portion of fine particles in comparing with wet sieving. Heavy metal contents and extractable metal contents were investigated for the sediments and high heavy metal content and extractable amount were obtained from fine particles as expected. Using of proper particle size analyzing method is important and the sediment management should be focused on the fine particles.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.6
• /
• pp.119-128
• /
• 2020

An ultrasonic multiple scattering simulation using cross-section of fine dust particles were proposed. These days, along with awareness of air pollution, social interest in fine dust is increasing. In the construction field, awareness of fine dust is increasing, and research on preparing various countermeasures is underway. The light scattering method fine dust meter currently in use is affected by environmental factors such as relative humidity, and reliability problems in terms of accuracy are continuously reported. However, the transmission of ultrasonic waves can directly reflect the physical change of the medium based on the mechanical wave. Using these advantages of ultrasonic waves, fine dust measurement simulation was performed using the scattering cross section and ultrasonic multiple scattering theory. The shape data of the fine dust particles were collected using a SEM (Scanning Electron Microscope), and a cross-section according to the fine dust particles was derived through numerical analysis. As a result of signal processing, the error for the number density corresponding to each cross-section is minimum 19, maximum 3455.

• Journal of Korea Entertainment Industry Association
• /
• v.13 no.6
• /
• pp.69-77
• /
• 2019

Among the many factors that threaten the improvement of public health and quality of life, the proportion of fine dust is not so small, and the kinds and causes of the dust are also diversified. However, the domestic measuring instrument is in the initial stage and the certification system is insignificant. Recognizing the threat of fine dust for a long time, the United States has established a protocol of measurement standards and measurement methods and applied the developed fine dust measuring device authentication system. Through this system, the United States is leading the world's fine dust industry, technology and market. The EPA, FRM and FEM of the fine dust-related protocol were analyzed to reduce the harmful effects of repeated fine dust every year. In addition, light scattering method and spectroscopy method which can measure in real time by measuring method were examined, and the types and characteristics of fine dust measuring instrument of international certification level were analyzed. Finally, development and service plan of the domestic fine dust measuring instrument are presented.

• Polymer(Korea)
• /
• v.33 no.5
• /
• pp.501-508
• /
• 2009

The thermal degradation experiment of sodium salt of poly (${\gamma}$-glutamic acid) (PGGNa) has been carried out in both its solid phase and solution phase at the range of $57{\sim}120^{\circ}C$ and their molecular weight decreasing effect was analyzed as a function of time by means of viscometry and light scattering. Based on the solid phase degradation results, it was supposed that the bond scission rate in a polymer chain kept constant and that the bond scission was occurred on a randomly located position in a polymer chain. For the degradation in solution phase, it was also found that all data at various temperatures were dropped on a single master curve when the reduced time $t/t^*$ was used in the plot of the reciprocal intrinsic viscosity (or molecular weight). This degradation curve in solution phase could be expressed as the sum of a single exponential and a linear equation and especially, the single exponential character appeared only at the beginning stage. The activation energy was measured as $107{\sim}115$ kJ/mol in this study and agreed with the literature values.

• Journal of Korean Society for Atmospheric Environment
• /
• v.26 no.5
• /
• pp.533-542
• /
• 2010

The $PM_{10}$ concentrations in the underground should be monitored for the health of commuters on the underground subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation are measuring several air pollutants regularly. As for the measurement of $PM_{10}$ concentrations, instruments based on $\beta$-ray absorption method and gravimetric methods are being used. But the instruments using gravimetric method give us 20-hour-average data and the $\beta$-ray instruments can measure the $PM_{10}$ concentration every one hour. In order to keep the $PM_{10}$ concentrations under a healthy condition, the air quality of the underground platform and tunnels should be monitored and controlled continuously. The $PM_{10}$ instruments using light scattering method can measure the $PM_{10}$ concentrations every less than one minute. However, the reliability of the instruments using light scattering method is still not proved. The purpose of this work is to study the reliability of the instruments using light scattering method to measure the $PM_{10}$ concentrations continuously in the underground platforms. One instrument using $\beta$-ray absorption method and two different instruments using light scattering method (LSM1, LSM2) were placed at the platform of the Jegi station of Seoul metro line Number 1 for 10 days. The correlation between the $\beta$-ray instrument and the LSM2 ($r^2$=0.732) was higher than that between the $\beta$-ray instrument and the LSM1 ($r^2$=0.393). Thus the LSM2 was chosen for further analysis. Three different regression analysis methods were tested: Linear regression analysis, Nonlinear regression analysis and Orthogonal regression analysis. When the instruments using light scattering method were used, the data measured these instruments have to be converted to actual $PM_{10}$ concentrations using some factors. With these analyses, the factors could be calculated successfully as linear and nonlinear forms with respect to the data. And the orthogonal regression analysis was performed better than the ordinary least squares method by 28.45% reduction of RMSE. These findings propose that the instruments using light scattering method light scattering method can be used to measure and control the $PM_{10}$ concentrations of the underground subway stations.

• Polymer(Korea)
• /
• v.27 no.3
• /
• pp.255-264
• /
• 2003

Various chain sizes 3-arm star polystyrenes (PS, $M_{w}$=2.80$\times$10$^{5}$ , 2.49$\times$10$^{6}$ g/mol) in t-decalin solution were measured at the temperature range of 20~7$0^{\circ}C$ by means of viscometry and laser light scattering. In order to show universality in the expansion factor of 3-arm star polymer, it was expected that (N/ $R_{G,Br,o}$$^{2}$)$^{3}$2/$\tau$/$\tau$$_{C}$ would be used as an universal parameter, where $R_{G,Br,o}$ was the unperturbed radius of gyration of star PS. However, much better universality had been observed when (N/ $R_{G,Br,o}$$^{2}$)$^{3}$2/$\tau$/$\tau$$_{C}$ parameter of the linear PS was used even for the 3-arm star PS. It could be explained if branching effect had been already taken into account in the part of $\tau$/$\tau$$_{C}$(=[(Τ-Θ$_{Tc}$ )/Θ$_{Tc}$ ]/[(Θ$_{Tc}$ -Τ$_{c}$)/ $T_{c}$]). Here N and Θ$_{Tc}$ stand for the number of monomer unit in a single polymer chain and a kind of theta temperature as the critical solution temperature $T_{c}$ of the infinite molecular weight, respectively.ely.y.ely.

• Korean Chemical Engineering Research
• /
• v.51 no.5
• /
• pp.622-627
• /
• 2013

Colloidal silica is used in various industrial products such as chemical mechanical polishing slurry for planarization of silicon and sapphire wafer, organic-inorganic hybrid coatings, binder of investment casting, etc. An accurate determination of particle size and dispersion stability of silica sol is demanded because it has a strong influence on surface of wafer, film of coatings or bulks having mechanical, chemical and optical properties. The study herein is discussed on the effect of measurement results of average particle size, sol viscosity and electrophoretic mobility of particle according to the volume fraction of eight types of silica sol with different size and surface properties of silica particles which are presented by the manufacturer. The measured particle size and the mobility of these sol were changed by volume fraction or particle size due to highly active surface of silica particle and change of concentration of counter ion by dilution of silica sol. While in case the measured sizes of small particles less than 60 nm are increased with increasing volume fraction, the measured sizes of larger particles than 60 nm are slightly decreased. The mobility of small particle such as 12 nm are decreased with increase of viscosity. However, the mobility of 100 nm particles under 0.048 volume fraction are increased with increasing volume fraction and then decreased over higher volume fraction.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.36 no.2
• /
• pp.105-113
• /
• 2010

This study introduces a flexible approach to enhance skin permeation by using ethosomes with deformable lipid membranes as well as controllable sizes. To demonstrate this, a set of ethosomes encapsulating an anti-hair loss ingredient, Triaminodil$^{TM}$, as a model drug, were fabricated with varying their size, which was achieved by solely applying the different level of mechanical energy, while maintaining their chemical composition. After characterization of the ethosomes with dynamic light scattering, transmission electron microscopy, and deformability measurements, it was found that their membrane deformability depended on the particle size. Moreover, studies on in vitro skin permeation and murine anagen induction allowed us to figure out that the membrane deformability of ethosomes essentially affects delivery efficiency of Triaminodil$^{TM}$ through the skin. It was noticeable in our study that there existed an optimum particle size that can not only maximize the delivery of the drug through the skin, but also increase its actual dermatological activity. These findings offer a useful basis for understanding how ethosomes should be designed to improve delivery efficiency of encapsulated drugs therein in the aspects of changing their length scales and membrane properties.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.26 no.1
• /
• pp.261-274
• /
• 2000

The o/w emulsions were prepared with saccharide surfactants which were sucrose monostearate(S160), sucrose distearate(S110), and POE(20) methyl glucose stearate(SSE20). And for emulsion the oils used were n-hydocarbon, squalane(SQ), liquid paraffin(LP), octylpalmitate(OP), octylstearate(OS), alkyl benzoate(AB), isostearyl benzoate(ISB). The structures of o/w emulsion droplet were investigated by laser light scattering and the fractal dimensions were calculated from light intensity curves. Increasing of concentration, chain length, and nonpolarity of oils, fractal dimensions of emulsion droplets were found greater. In general fiactal dimensions were varied from 1.7 to 2.8 and its structures were fractal But the fractal dimensions of octadecane( $C_{18}$), 50, and LP emulsified with S110 and S160 were varied from 3.0 to 3.2 and its structures were more dense. The overall fractal dimensions of S110 and S160 were varied from 2.1 to 2.6, that of SSE20 were varied from 1.5 to 2.1. So it was found that the structures of SSE20 system were less compact than that of S110 and S 160 system, because the hindrance effect of polyoxyehtylene group of SSE20 was stronger than that of sucrose of S160. The strucures of emulsion droplets changed according to the nature of emulsifiers and to compositions of oil substances which they contained, and the structures were found similar when the hydophilic moiety of emulsifiers was same.