• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.6
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• pp.244-249
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• 2006

Electrostatic spray pyrolysis, a novel fabrication technique, has been used in this study to prepare calcium phosphate nano powders. Final annealing was done at $400^{\circ}C$ for 30min in air. The hydroxyapatite - forming ability of the annealed powder has been evaluated in Eagle's minimum essential medium solution (MEM). X-ray diffraction analysis, field emission - scanning electron microscope, energy dispersive X-ray spectroscope, and Fourier transform infrared spectroscope were used to characterized the annealed powders after immersion in MEM. The powder with an amorphous structure induced hydroxyapatite formation on their surfaces after immersion fer 15 days.

• Polymer(Korea)
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• v.37 no.4
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• pp.442-448
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• 2013

In this study, we developed and optimized hydrophilic polymer-based solid dispersion formulations (SDs) using a spray drying method for improving the aqueous solubility of eprosartan, one of poorly soluble drugs that has been broadly used for the treatment of high blood pressure. Hydroxylpropylcellulose (HPC) and poly(vinyl pyrrolidone) (PVP) were used as hydrophilic polymer matrices and poloxamer 407 (P407) added as a polymeric surfactant. Various kinds of solid dispersions with different drug/polymer compositions were prepared and their physico-chemical properties were compared. As the polymer content increased, the drug crystallinity in the SDs significantly decreased and the dissolution properties were enhanced. The PVP based SDs were observed to have relatively reduced crystallinity and an enhanced dissolution rate than HPC-based SDs, due to better miscibility between drug and polymer matrix. For PVP based SDs, the drug crystallinity almost disappeared and the dissolution properties significantly increased by more than 3~7 times.

• Smart Media Journal
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• v.8 no.4
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• pp.38-45
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• 2019

When there is a spray flow such as from a pesticide nozzle, winds affect the droplet flow of a rotary-wing drone accompanied by a strong wake, with a severe oscillation. Especially, during forwarding flights or when winds come from the side, compare to a simple hovering flight as the droplet is in the effect of aerodynamic drag force, the effect of spraying region becomes even larger. For this reason, the spraying of pesticides using drones may cause a greater risk of scattering or a difference in droplet dispersion between locations, resulting in a decrease in efficiency. Therefore, through proper numerical modeling and its applied simulation, an indication tool is required applicable for the various flight and atmospheric conditions. In this research, we completed both experiment and numerical analysis for the strong downwash from the rotor and flight velocity of the drone by comparing the probability density function of droplet distribution to build a spraying system that can improve the efficiency when spraying droplets in the pesticide spray drone.

• Food Engineering Progress
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• v.15 no.1
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• pp.28-33
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• 2011

UV-C and -B types of lamps, and $H_2O_2$ as a photocatalytic material were applied to optimize processing conditions for pesticides removal in Mandarine orange peel. Factors to affect the removal of pestrcides were arranged as a function of irradiation temperature, irradiation time, and $H_2O_2$ spray concentration. The optimum processing conditions for the chloropyrifos and the EPN removals in Mandarine orange peel were irradiation time of 60 min, irradiation temperature of $45^{\circ}C$ and $H_2O_2$ spray concentration of 1000 ppm. However, the optimum processing conditions for methidathion removal were 60 min of irradiation time, $40^{\circ}C$ of irradiation temperature and 1000 ppm of $H_2O_2$ spray concentration. The residual percentages of chloropyrifos, EPN and methidathion were 46, 49 and 28% after above irradiation processing, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.264-269
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• 2021

In this study, amorphous aluminum silicate powder was prepared using co-precipitation method, and the influence of spray-dried aluminum silicate granular powder was analyzed and optimized by controlling the amount of aluminum silicate powder and dispersant added to the slurry. As a result, granular powder was optimally produced under the conditions of powder content of aluminum silicate slurry of 27.5 wt% or less, dispersant addition amount of 0.8 wt% or more, pH 6~9. An average particle size of granular powder showed approximately 14 ㎛ at the powder contents of 20 and 22.5 wt% of the slurry, and approximately 19 ㎛ at the powder contents of 25 and 27.5 wt% of the slurry.

• Analytical Science and Technology
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• v.19 no.6
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• pp.519-528
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• 2006

An analytical method for the determination of thyroid hormones in urine samples has been studied by using solid-phase extraction and high-performance liquid chromatography/diode array detector/electro-spray mass spectrometry. Seven thyroid hormones were successfully separated by gradient elution on the reverse phase Hypersil ODS column (4.6 mm I.D., 100 mm length, particle size $5{\mu}m$) with ammonium formate buffer and acetonitrile, and UV spectra and mass fragment could be confirmed. The extraction recoveries of thyroid hormones in the urine samples (pH 3) were in the range of 89.0-113.1% with solid-phase extraction by C18, followed by elution with 4 ml of methanol/ammonium hydroxide (9 : 1). The calibration curves showed good linearity with the correlation coefficients ($r^2$) varying from 0.992 to 0.998 and the detection limits of all analytes were obtained in the range of 2-4 ng/ml (3.8-13.0 pmol/ml).

• Solar Energy
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• v.10 no.2
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• pp.69-76
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• 1990

Photoelectrochemical decomposition of water by the irradiation of light to the $TiO_2$ thin film soaked in water was observed. The $TiO_2$ thin film was coated on top of $SnO_2$ nesa glass by use of spray method and of dip-coating method. The spray technique of $SnO_2$ nesa film production and dip-coating technique of $TiO_2$ thin film preparation on top of the $SnO_2$ nesa film were discribed briefly. $TiO_2$ film appearance was observed by SEM and I-V characteristic curve were measured for the various thickness of $TiO_2$ film. The film Thickness $1.8{\mu}m$ showed the maximum photoelectric current. Xe-lamp was used as light source for the photoelectrochemical reaction of thin film $TiO_2$ in acidic water(pH=1)

• Corrosion Science and Technology
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• v.17 no.5
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• pp.211-217
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• 2018

Natural degradation of grounding-electrode in soil environment should be monitored for several decades to predict the lifetime of the grounding electrode for efficient application and management. However, long-term studies for such electrodes have many practical limitations. The conventional accelerated corrosion test is unsuitable for such studies because simulated soil corrosion process cannot represent the actual soil environment. A preliminary experiment of accelerated corrosion test was conducted using existing test standards. The accelerated corrosion test that reflects the actual soil environment has been developed to evaluate corrosion performances of grounding-electrodes in a short period. Several test conditions with different chamber temperatures and salt spray were used to imitate actual field conditions based on ASTM B162, ASTM B117, and ISO 14993 standards. Accelerated degradation specimens of copper-bonded electrodes were made by the facile method and their corrosion performances were investigated. Their corrosion rates were calculated to $0.042{\mu}m/day$, $0.316{\mu}m/day$, and $0.11{\mu}m/day$, respectively. These results indicate that accelerated deterioration of grounding materials can be determined in a short period by using cyclic test condition with salt spray temperature of $50^{\circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.37-40
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• 2005

High Performance Concrete(HPC) has been widely used in high-rise building. The HPC has several benefits including high strength, high fluidity and high durability. However. spatting is susceptible to occur in HPC and HPC also tends to be deteriorated in the side of fire resistance performance at fire. This paper focuses on the analysis of the temperature history and residual compressive strength with finishing material, in order to protect HPC from sudden-high-temperature, which is one of the main reason spatting occurs. Test results show that spalling occurs in all specimens. The most serious spalling took placed in HPC covering fire enduring spray-on material, whose covering thickness is 20mm but temperature history indicates that fire enduring spray effectively protected HPC from fire for more than 2hours. In addition, residual compressive strength ratio of HPC using fire enduring paint was more than $90\%$ of original strength, thus minimizing spatting and indicating significant fire resistance performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.877-880
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• 2011

A coaxial swirl/shear injector using GCH4/LOx as propellants was degisned and manufactured. Flow analysis by Fluent was performed to decide the number of orifice and the rear shapes of inlet orifice etc. Flow rate of the injector was measured according to differential pressure and uniformity of injector's spray pattern was confirmed by a patternator. The results showed that the difference of flow rate was around 10% and the spray angle of oxidizer was $66^{\circ}$.