In a nuclear facility, the base metal can be radiologically contaminated during the operation. They must be decontaminated to reduce the radiation exposure to workers before decommissioning of the nuclear facility. In order to decontaminate the nuclear facility, it is possible to apply a perfluorocarbon (PFC) based emulsion consisted of surfactant and decontamination reagent. The PFC has high resistance for the radiation decomposition, and PFC based emulsion can be easily stabilized using the ultrasonication method. During decontamination process, a dispersion stability of the emulsion affects to the decontamination performance because the decontamination reagents dispersed in the emulsion contact contaminated surface. In this study, the dispersion stability the PFC based emulsion was evaluated following the composition of the emulsion and dispersion condition such as temperature, ultrasonication time. It was confirmed that the concentration of surfactant is highly related to the dispersion stability from the result of Turbiscan analysis using the multiple light scattering method. It was also verified that the droplet size of the decontamination reagent in the stable emulsion was smaller than that in the unstable emulsion. This phenomena can be explained by the relationship between the interfacial tension and droplet size. Finally, the recovering test of the PFC from the spent PFC-based decontamination emulsion was conducted using distillation method. The distillation test was performed using vacuum distillation unit, and the distillation temperature was 80°C. From the distillation test, about 95 % of PFC was recovered by distillation. From this result, it is considered that PFC-based decontamination emulsion reduces the volume of the secondary waste.

To enhance mechanical properties through improvement of dispersion stability of carbon black (CB) in epoxy resins, fluorine functional groups were introduced on the CB surface by fluorination. The changes in the chemical properties and dispersion stabilities after fluorination were evaluated with different partial pressures of fluorine gas. The mechanical properties of the fluorinated CB/epoxy composites were evaluated by the test of tensile, impact strengths and creep behavior. The fluorinated CB/epoxy composites showed approximately 1.6 and 1.1 times enhancement in the tensile and impact strengths compared to that of neat epoxy, respectively. Moreover, when a constant load was applied at 323 K, the fluorinated CB/epoxy composites lasted longer and had smaller strain changes than those of the raw CB/epoxy composites. Thus, well-dispersed CB by fluorination in epoxy resins effectively transfers mechanical stress.

This study examines the role of the nano- and micro-particle ratio in dispersion stability and mechanical properties of composite resins for SLA(stereolithography) 3D printing technology. VTES(vinyltriethoxysilane)-coated ZrO2 ceramic particles with different nano- and micro-particle ratios are prepared by a hydrolysis and condensation reaction and then dispersed in commercial photopolymer (High-temp) based on interpenetrating networks(IPNs). The coating characteristics of VTES-coated ZrO2 particles are observed by FE-TEM and FT-IR. The rheological properties of VTEScoated ZrO2/High-temp composite solution with different particle ratios are investigated by rheometer, and the dispersion properties of the composite solution are confirmed by relaxation NMR and Turbiscan. The mechanical properties of 3Dprinted objects are measured by a tensile test and nanoindenter. To investigate the aggregation and dispersion properties of VTES-coated ZrO2 ceramic particles with different particle ratios, we observe the cross-sectional images of 3D printed objects using FE-SEM. The 3D printed objects of the composite solution with nano-particles of 80 % demonstrate improved mechanical characteristics.

The improvement of dispersion stability for the primary polishing slurry in a CMP process is achieved to prevent defects produced by agglomeration of the slurry. The dispersion properties are analyzed according to the physical characteristics of each silica sol sample. Further, the difference in the dispersion stability is confirmed as the surfactant content. The dispersibility results measured by Zeta potential suggest that the dispersion properties depend on the content and size of the abrasive in the primary polishing slurry. Moreover, the optimum ratio for high dispersion stability is confirmed as the addition content of the surfactant. Based on the aforementioned results, the long-term stability of each slurry is analyzed. Turbiscan analysis demonstrates that the agglomeration occurs depending on the increasing amount of surfactant. As a result, we demonstrate that the increased particle size and the decreased content of silica improve the dispersion stability and long-term stability.

Odor dispersion from road emissions were investigated using CFD (Computational Fluid Dynamics). The Shear Stress Transport k-ω model in FLUENT CFD code was used to simulate odor dispersion around the road. The two road configurations used in the study were at-grade and fill road. Experimental data from the wind tunnel obtained in a previous study was used to validate the numerical result of the road dispersion. Five validation metrics are used to obtain an overall and quantitative evaluation of the performance of Shear Stress Transport k-ω models: the fractional bias (FB), the geometric mean bias (MG), the normalized mean square error (NMSE), the geometric variance (VG), and the fraction of predictions within a factor of two of observations (FAC2). The results of the vertical concentration profile for neutral atmospheric show reasonable performance for all five metrics. Six atmospheric stability conditions were used to evaluate the stability effect of road emission dispersion. It was found that the stability category D case of at-grade decreased the non-dimensional surface odor concentration smaller 0.78~0.93 times than those of stability category A case, and that F case decreased 0.39~0.56 times smaller than those of stability category A case. It was also found that stability category D case of filled road decreased 0.84~0.92 times the non-dimensional surface odor concentration of category A case and stability category F case decreased 0.45~0.58 times compared with stability category A case.

The dielectric medium used in electrophoretic displays (EPDs) is required to be an environmentally friendly solvent with high density, low viscosity, and a large electric constant. Hydrofluoroether, a highly fluorinated solvent with eco-friendly characteristics, is regarded as a viable alternative medium for EPDs, owing to the similarity of its physical properties to those of the conventional EPD medium. Surface modification of particles is required, however, in order for it to disperse in the charged solvent. Also, positive/negative charges should be present on the particle surface to enable electrophoretic behavior. In this study, carbon black particles wrapped with positively charged nitrogen (N-CBs) were fabricated by a simple hydrothermal process using a poly(diallyldimethylammonium chloride) solution as a black coloring agent for the EPD. The dispersion behavior of N-CBs was investigated in various solvents.

The aim of this study was to improve dispersion stability of calcium carbonate (CaCO3) nanoparticles in aqueous medium using alkyl polyglucoside (APG). One hundred milligrams of CaCO3 nanoparticles was mixed with 30 mL of deionized water. Thereafter, APG was dissolved into the CaCO3 nanoparticle mixtures at approximate 0, 0.1, 0.3, 0.5, 0.7, and 0.9%, and subsequently, pH was adjusted to 7.0 and 10.0. Afterward, all CaCO3 nanoparticle mixtures were dispersed by ultrasonic processing treatment for 10 min. Dispersion stability and physicochemical properties of the CaCO3 nanoparticle mixtures were observed by measuring the change of absorbance and mean diameter for 96 h as well as the initial zeta-potential. As results, initial zeta-potentials of the CaCO3 nanoparticles in deionized water at pH 7.0 and 10.0 showed approximately +20 and 0, respectively. The positive surface charge at pH 7.0 had unfavorable impact on the adsorption of APG onto CaCO3 nanoparticles in the aqueous suspensions because APG is nonionic surfactant. Among all samples at pH 10, CaCO3 nanoparticles in 0.5% APG aqueous solution showed the smallest initial mean diameter and the slowest increase in mean diameter and decrease in absorbance. In conclusion, the pH 10.0 and 0.5% APG concentration was the most desirable condition in order to improve dispersion stability of CaCO3 nanoparticles in an aqueous medium.

NiO catalysts/Al2O3/FeCrAl alloy foam for hydrogen production was prepared using atomic layer deposition (ALD)and subsequent dip-coating methods. FeCrAl alloy foam and Al2O3 inter-layer were used as catalyst supports. To improve thedispersion and stability of NiO catalysts, an Al2O3 inter-layer was introduced and their thickness was systematically controlledto 0, 20, 50 and 80nm using an ALD technique. The structural, chemical bonding and morphological properties (includingdispersion) of the NiO catalysts/Al2O3/FeCrAl alloy foam were characterized by X-ray diffraction, X-ray photoelectronspectroscopy, field-emission scanning electron microscopy and scanning electron microscopy-energy dispersive spectroscopy. Inparticular, to evaluate the stability of the NiO catalysts grown on Al2O3/FeCrAl alloy foam, chronoamperometry tests wereperformed and then the ingredient amounts of electrolytes were analyzed via inductively coupled plasma spectrometer. We foundthat the introduction of Al2O3 inter-layer improved the dispersion and stability of the NiO catalysts on the supports. Thus, whenan Al2O3 inter-layer with a 80nm thickness was grown between the FeCrAl alloy foam and the NiO catalysts, it indicatedimproved dispersion and stability of the NiO catalysts compared to the other samples. The performance improvement can beexplained by optimum thickness of Al2O3 inter-layer resulting from the role of a passivation layer.

The blending schemes of Saengshik powder with water were established to retain the dispersion stability of the Saengshik beverage in order to develop a ready-to-drink type product. The effect of the blending on the rheological properties and the dispersion stability of Saengshik beverage were determined. The Saengshik beverages, blended with low shear force for a short time, showed dilatant fluid characteristics, while those with high shear force for a long time had pseudoplastic fluid ones. The consistency of Saengshik beverage increased with the blending speed and time. Saengshik beverage blended at low shear showed rheopexy while becoming time independent by a highshear blending action. A logarithmic model fitted well to the changes in backscattering light flux with the rest time of Saengshik beverage. Based on sedimentation kinetics, the migration speed of clear front, and the thickness of sedimented layer, Saengshik beverage with maximum dispersion stability was obtained by a high shear blending at 15,120 rpm for 25 s.

Atmospheric stability is an important parameter which effects pollutant dispersion in the atmospheric boundary layer.The objective of this paper was to verify the effect of stability conditions on odor dispersion downwind from anarea source using computational fluid dynamic (CFD) modeling. The FLUENT Realizable k-ε model was used tosimulate odor dispersion as released by an odor source. A total of 3 simulations demonstrated the effects of unstable,neutral, and stable atmospheric conditions. Unstable atmospheric stability conditions produced a shorter odor plumelength compared with neutral and stable conditions because of stronger convective effects. Like other studies,unstable atmospheric condition produced higher plume height compared with neutral and stable conditions.

생식 첨가량을 3.7-11.7%로 조절한 생식음료의 분산안정성을 터비스캔을 사용하여 광학적 방법으로 측정하였다. 생식음료는 제조 후 시간이 경과함에 따라 음료 하부에서는 침전이 생성되어 후방산란광플럭스(이후 후광플럭스로 약칭)가 강해진 반면, 중간부에서는 청징현상에 의해 약해졌으며, 최상층부에서는 거품이 생성되어 다시 강해졌다. 생식 첨가량이 증가할수록 침전이 서서히 진행되었으며 전체 침전층은 두텁게 형성되었다. 침전에 의한 후광플럭스의 퍼센트변화율의 시간에 따른 변화는 로그 모델이 적용되었으며 결정계수는 0.979-0.988로 높은 값을 보였다. 생식 첨가량은 생식음료의 상층부에 형성되는 청징층과 하층부의 침전층의 경계면, 즉 청징층 선단의 이동속도 뿐 만 아니라 분리된 층의 수에도 영향을 미쳤다. 생식 첨가량 3.7%의 경우는 2층으로, 5.7-9.7%의 경우는 3개 층으로, 11.7%는 4개 층으로 분리되었다. 생식음료 제조 후 17-29분 사이에 1차 청징층 발생이 시작되었고 22-53분간 지속되었으며, 생식첨가량이 낮을수록 청징층 두께는 증가하였다. 청징층 발생은 생식 첨가량 7.7%인 음료에서 가장 늦게 나타나 최대 분산안정성을 보였다.

The surface of magnetite () nanoparticles prepared by coprecipitation method was modified by carboxylic acid group of poly(3-thiophenacetic acid (3TA)) and meso-2,3-dimercaptosuccinic acid (DMSA). Then the lysozyme protein was immobilized on the carboxylic acid group of the modification of the magnetite nanoparticles. The magnetite nanoparticles are spherical and the particle size is approximately 10 nm. We measured quantitative dispersion state by dispersion stability analyzer for each nanoparticles with and without surface modification. The concentration of lysozyme on the modified magnetite nanoparticles was also investigated by a UV-Vis spectrometer and compared to that of magnetite nanoparticles without surface modification. The functionalized magnetite particles had higher enzymatic capacity and dispersion stability than non-functionalized magnetite nanoparticles

The sodium α-sulfo fatty acid vinyl ester oligomers, which are oligomer type surfactants were prepared by polymerization with fatty acid vinyl acetate. The α-sulfonation of fatty acid vinyl ester oligomers were carried by direct addition of sulfur trioxide. The dispersing performance of oligomer type anionic surfactants and sodium dodecyl sulfate(SDS) in the aqueous suspension of iron oxide and titanium dioxide particles was evaluated by particle size distribution and zeta-potential measurement. As results, the particles of iron oxide and titanium dioxide were flocculated by addition of small amount of oligomer type anionic surfactants and sodium dodecyl sulfate(SDS), then the flocks redispersed by more addition of oligomer type anionic surfactants and SDS. The flocculation, redispersion process was observed in lower concentration range of oligomer type anionic surfactants than SDS. Especially, the dispersing action of sodium α-sulfo palmitic acid vinyl ester oligomer was better than sodium α-sulfo lauric acid vinyl ester oligomer.

In this outline, the stability of solid/liquid dispersion was theoretically investigated the matter from all angles by using the modified DLVO theory. The stability was handled various considerations such as a production and characteristics of electrical double layer, total interaction(VT) that consisting of attractive force(VA) and repulsion(VR). coagulation, the stability ratio(W), critical flocculation concentration (cfc) and zeta potential(ξ) etc. It was possible for us to examine with the stability ratio(W), critical flocculation concentration (cfc) and zeta potential(ξ) that may estimation of stability of solid/liquid dispersion experimentally.

A Stability to the dispersion solvent, which is acetonitrile, dichloromethane, benzene, chloroform and acetonitrile-benzene(1:1,v/v) of N-docosyl pyridinium)-TCNQ(1:2)complex was investigated by U.V Spectrophotometer and was confirmed stabilized on acetonitrile, the dichloromethane and acetonitrile-benzene (1:1,v/v) for seven hours. Using CdCl2buffer solution as subphase for LB films deposition, it was achived successively to fabricate the Y-type LB films of (N-docosyl pyridinium)-TCNQ(1:2)complex. For the sake of verifying the deposition of LB films, U.V is measured by variation of nominal layer number.