• The Korea Journal of Herbology
• /
• v.28 no.5
• /
• pp.79-85
• /
• 2013

Objectives : This study was aimed at producing emulsion by using butanol fractions of Sanguisorbae radix(SRA-B) which have high antioxidative and anti-inflammatory actions, and then evaluating stabilities of the emulsion. Methods : We measured antioxidant efficacy of SRA-B by using DPPH assay. Also, we checked the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) by using the Western blot to evaluate the anti-inflammatory effects of SRA-B3. We prepared emulsion containing SRA-B3(E-SRA-B3) and analysed its particle size distribution under a microscope. Also, we performed the test for stability of the emulsion. Results : SRA-B3 showed the highest efficacy in electronic donating abilities' activity. The Western blot's results indicated that the protein expression's amount of iNOS and COX-2 in macrophage stimulated by LPS were reduced by SRA-B3 treatment. The average particle size of E-SRA-B3 was $5{\sim}6{\mu}m$ in diameter and was $6.7{\mu}m$ in a view of the particle distribution. For a period of a observation, E-SRA-B3 has not made particular changes with storage temperature. It was observed that E-SRA-B3 could preserve its stable condition without a particular difference of viscosity during 28 days. Conclusions : From the above results, it was confirmed that SRA-B3 has potentiality enough to be applied to industrialization and could be utilized as antioxidative natural materials and anti-inflammatory cosmetics.

• Korean Chemical Engineering Research
• /
• v.57 no.1
• /
• pp.105-110
• /
• 2019

Effect of height on the size and shape of carbon nanotube (CNT) aggregates in the freeboard region of a bubbling fluidized bed ($0.15m\;i.d.{\times}2.6m\;high$) has been determined. Feret diameter and Heywood diameter of the CNT aggregates in the freeboard region of fluidized bed increased with increasing gas velocity. The average aggregate diameters and CNT particle number in the aggregates decreased with increasing of height in the freeboard. Aspect ratio increased as the location was closer to the surface of the dense phase, but decreased at the highest location. Solidity did not show any significant changes with height. The results showed the aggregates formation process is affected by the height in the freeboard. A correlation was proposed to predict the Heywood diameter of the CNT aggregates.

• Journal of the Korean Ceramic Society
• /
• v.35 no.6
• /
• pp.594-602
• /
• 1998

Titanium hydroxide (TiO({{{{ {OH }_{2 } }})) fine particles were produced by the reverse micelle technique. For the formation of titanium hydroxide (TiO({{{{ {OH }_{2 } }})) particles with the technique reversed micellar solution was prepared by solubilizing water into organic solvent (isooctane) with a surfactant and titanium alkoxide (tetraisopropyl orthotitanate) diluted with isopropyl alcohol was added to the reversed micellar solution. The hdrolyzed species (TiO({{{{ {OH }_{2 } }})) was formed by the hydrolysis of titanium alkoxide and titanium dioxide is then formed by the condensation of the hydrolyzed species. There are several process variables such as surfactants concentration of surface cosurfactant hydrolysis temperature and pH. In this work the ef-fects of process variables on paticle shapes particle size distribution and paticle agglomeration were bi-nodal for an anionic surfactant(AOT) in the whole range of temperature pH and surfactant concentration of this experiment. The addition of ethanol as a cosurfactant resulted in narrow particle size distribution of the experiment. The additiono of ethanol as a cosurfactant resulted in narrow particle size distribution and 0.12${\mu}{\textrm}{m}$ of smaller average particle diameter. FT-IR spectrum of particles shows the absorption peak of Ti-OH bonding and Ti-O bonding. An exothermic peak around 41$0^{\circ}C$ in TGA-DTA curve shows that crys- tallized anatase phase appears and completely transits to anatase around 45$0^{\circ}C$.

• Journal of Korean Society for Atmospheric Environment
• /
• v.33 no.6
• /
• pp.616-625
• /
• 2017

Measurements using five real-time particle samplers were compared to measurements using three NRM (National Reference Method system) filter-based samplers(Gravimetric method) at Incheon, Korea, between May and August, 2014. The purpose of this study was to suggest the quality assurance/quality control (QA/QC) method of each instrument for use in a real-time continuous particle sampler to measure the mass of airborne particles with an aerodynamic diameter less than $2.5{\mu}m$ ($PM_{2.5}$). Five real-time particle samplers of BAM1020, FH62C_14, TEOM, PM-711 and SPM-613 were evaluated by comparing its measured 23 hr average $PM_{2.5}$ concentrations with those measured with NRM filter-based samplers simultaneously. The parameters(e.g. Inlet heating condition, Slope factor, Film response, Intercept, Background, Span value) of the real-time samplers were optimized respectively by conducting test performance evaluation during 7 days in field sampling. For example, inlet heating temperature of TEOM sampler controls $35{\sim}40^{\circ}C$ to minimize the fluctuation of the real-time measurement data and background value of BAM1020 is the key factor affecting the accuracy of $PM_{2.5}$ mass concentration. We classified the $PM_{2.5}$ concentration according to relative humidity (80%) to identify water absorbed in aerosols by measuring the ${\beta}$-ray samplers(BAM1020, FH62C_14) and TEOM. ${\beta}$-ray samplers were not strongly affected by relative humidity that the difference of the average $PM_{2.5}$ concentration was about 5%. On the other hand, The TEOM sampler overestimated $PM_{2.5}$ mass concentration about 15% at low relative humidity (<80%).

• Korean Journal of Ecology and Environment
• /
• v.37 no.4 s.109
• /
• pp.423-430
• /
• 2004

This study intended to understand movements of turbid water in selective with drawal reservoirs before and after summer monsoon. Mean rainfall during November-May was low, compared to that during June-October. The reservoir water was discharged through watergates when previous rainfall and inflow exceeded 50 mm and $80\;m^3s^{-1}$, respectively. Intake towers were generally used except for the period of the high runoff. Average turbidity in gown-reservoir showed a difference of 29.9 NTU between premonsoon and postmonsoon. Diameter of particles of turbid water ranged between 0.435 and $482.9\;{\mu}m$. Fine particles such as clay were much denser than the larger particle. In the whole stations, clay component was relatively higher with a proportion of that in the particle distribution. Particle composition of turbid water showed that clay consisted of 94.4-98.9% and silt made of 1.1-5.6%. Analysis on turbid water movements derived from particle distribution showed a linear increase from the deep layer toward the surface layer in lower area of a reservoir. This was closely related with the hydraulic behavior of the reservoir, and heavily affected by the discharges through selective withdrawal towers and watergates. Turbid water originated from stream sediments in the middle area then resuspended in the down-reservoir causing a movement between the surface and middle layers of the reservoir. Therefore, such phenomenon needs to be understood for reservoir water quality management.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.6
• /
• pp.528-535
• /
• 2004

Ultrasonic Vibrator is designed to achieve the maximum vibration amplitude at 30 kHz by in-cluding a horn (diameter, 40 mm), mechanical vibration amplifier at the top of the ultrasonic vibrator in the system and making the complete system resonate. In addition, it is experimentally visualized by particle imaging velocimetry (PIV) that the acoustic streaming velocity in the gap is at maximum when the gap between the ultrasonic vibrator and stationary plate agrees with the multiples of half-wavelength of the ultrasonic wave. This fact results from the resonance of the sound wave and the theoretical analysis of that is also accomplished and verified by experiment. It is observed that the magnitude of the acoustic streaming dependent upon the gap between the ultrasonic vibrator and stationary plate possibly changes due to the measurement of the average velocity fields of the acoustic streaming induced by the ultrasonic vibration at resonance and non-resonance. There exists extremely small average velocity at non-resonant gaps while the relatively large average velocity exists at resonant gaps compared with non-resonant gaps. It also reveals that there should be larger axial turbulent intensity at the hub region of the vibrator and at the edge of it in the resonant gap where the air streaming velocity is maximized and the flow phenomena is conspicuous than that at the other region. Because the variation of the acoustic streaming velocity at resonant gap is more distinctive than that at non-resonant gap, shear stress increases more in the resonant gap and is also maximized at the center region of the vibrator except the local position of center (r〓0). At the non-resonant gap there should be low values of vorticity distribution, but in contrast to the non-resonant gap, high and negative values of it exist at the center region of the vibrator with respect to the radial direction and in the vicinity of the middle region with respect to the axial direction. Acoustic streaming is noise-free due to the ultrasonic vibration and maintenance-free because of the absence of moving parts. Moreover, the proposed method by acoustic streaming can be utilized to the nano and micro-electro mechanical systems as a driving mechanism in addition to the augmentation of the streaming velocity.

• Polymer(Korea)
• /
• v.39 no.1
• /
• pp.78-87
• /
• 2015

With aiming to prepare microcapsules having a particle size of $30-50{\mu}m$, thermally expandable capsules with relatively uniform particle sizes consisting of a n-octane/poly(acrylonitrile-co-methyl methacrylate) core/shell structure were synthesized using SPG membrane emulsification and suspension polymerization. Four steric stabilizers and five crosslinking agents were employed. When poly(vinyl alcohol) as a stabilizer was used, the prepared capsules showed a smooth and regular morphology and the liquid hydrocarbon (n-octane) was well encapsulated in the core. When 1,4-butnaediol methacrylate (BDDMA) was used as a crosslinker, the uniform capsules with the average diameter of $36.8{\mu}m$ were synthesized. The capsules prepared with 0.05 mol% BDDMA showed the best encapsulation efficiency.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.96-96
• /
• 2016

Nanotechnology mostly employs nano-materials and nano-structures with distinctive properties based on their size, structure, and composition. It is quite difficult to produce nano-materials and nano-structures with identical sizes, structures, and compositions in large quantities, because of spatiotemporal fluctuation of production processes. In other words, fluctuation is the bottleneck in nanotechnology. We propose three strategies to suppress such fluctuations: employing 1) difference between linear and nonlinear phenomena, 2) difference in time constants, and 3) nucleation as a bottleneck phenomenon. We are also developing nano- and micro-scale guided assembly using plasmas as a plasma nanofabrication.1-5) We manipulate nano- and micro-objects using electrostatic, electromagnetic, ion drag, neutral drag, and optical forces. The accuracy of positioning the objects depends on fluctuation of position and energy of an object in plasmas. Here we evaluate such fluctuations and discuss the mechanism behind them. We conducted in-situ evaluation of local plasma potential fluctuation using tracking analysis of fine particles (=objects) in plasmas. Experiments were carried out with a radio frequency low-pressure plasma reactor, where we set two quartz windows at the top and bottom of the reactor. Ar plasmas were generated at 200 Pa by applying 13.56MHz, 450V peak-to-peak voltage. The injected fine particles were monodisperse methyl methacrylate-polymer spheres of $10{\mu}m$ in diameter. Fine particles were injected into the reactor and were suspended around the plasma/sheath boundary near the powered electrode. We observed binary collision of fine particles with a high-speed camera. The frame rate was 1000-10000 fps. Time evolution of their distance from the center of mass was measured by tracking analysis of the two particles. Kinetic energy during the collision was obtained from the result. Potential energy formed between the two particles was deduced by assuming the potential energy plus the kinetic energy is constant. The interaction potential is fluctuated during the collision. Maximum amplitude of the fluctuation is 25eV, and the average is 8eV. The fluctuation can be caused by neutral molecule collisions, ion collisions, and fluctuation of electrostatic force. Among theses possible causes, fluctuation of electrostatic force may be main one, because the fine particle has a large negative charge of -17000e and the corresponding electrostatic force is large compared to other forces.

• Journal of Powder Materials
• /
• v.15 no.1
• /
• pp.13-17
• /
• 2008

Visible-light responsive $TiO_2$:Zr, N powders were prepared by polymer complex solution method and the particle properties were characterized by using transmission electron microscope, BET method, X-ray diffractometer and UV-Vis spectrophotometer. The photocatalytic reactivity of the catalysts was also estimated by analyzing NO degradation. Polyhedral $TiO_2$ powder having about 20 um in the average particle diameter was successfully prepared, The XRD analysis revealed that the as-prepared powder consisted of anatase and rutile phases. The light absorption of the as-prepared $TiO_2$:Zr, N powder was shifted to the visible light. In addition, the as-prepared $TiO_2$:Zr, N nanoparticles showed the higher photocatalytic activity than the commercial $TiO_2$ under both UV and visible lights.

• Journal of Korean Society for Atmospheric Environment
• /
• v.8 no.1
• /
• pp.20-28
• /
• 1992

The x-ray fluorescence(XRF) is one of the most convenient and widely used techniques for analyzing trace elements in ambient particulate matters. The objects of the study were to estimate the optimum exposure time using the XRF, to investigate the distributions of heavy metal levels in particulate matters, and finally to study seasonal variation for the concentrations of total suspended particulate matters(TSP) and size fractionated particulate matters. The suspended particulate matters had been collected by a cascade impactor having 9 size fragnated stages for 3 years(Dec. 1988 to Nov. 1991) in Kyung Hee University-Suwon Campus. The particulate matters were then collected on each stage by membrane filters. The weight concentrations were determined by the XRF system. Thus, seasonal variations and relationship between concentration and particle size could be investigated. Resulting distribution was bimodal with the coarse and the fine particle groups minimum occurring around 2.1 to 3.3 $\mu$m as an aerodynamic diameter. To determine optimum exposure time of the XRF for various trace inorganic elements, membrane filters and the NIST standard filters were extensively studied. Using a statistical technique, optimum exposure time was estimated for each trace element and overall elements. The time was then determined as 20 seconds for the XRF system. The concentration of TSP was 123.9$\mum/m^3$ on an arithmatic average. The levels of each inorganic metal were Si 2420.0ng/$m^3$, Fe 977.1ng/$m^3$, and so on. The Pb. Zn, and Cu abounded in the fine mode group, while Ca, Fe, Si, Al, and K in the coarse group. Marked seasonal variation of TSP and metal concentrations was observed. The concentration of heavy metals in the fine mode was highest in winter : on the other hand, that in the coarse mode was highest in spring.