• Textile Coloration and Finishing
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• v.20 no.6
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• pp.8-17
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• 2008

Poly (vinyl acetate) (PVAc) was used as a precursor of PVA/PVAc (skin/core) bicomponent. In order to investigate the possibility of PVA particles for electrical applications, PVA/PVAc particles were produced with an emulsifier, SDS (Sodium Dodecyl Sulfate) and an initiator, V-50 (2,2'-azobis(2-amidinopropane)digydrochloride). In this study, we investigated the electrical property of PVA/PVAc (skin/core) particles. The hydroxyl group of the PVA/PVAc (skin./core) was confirmed by the analysis of PVAc and PVA/PVAc (skin/core) using Fourier Transform Infrared Spectroscopy (FT-IR). The zeta-potential of the PVA/PVAc (skin/core) and PVAc has similarity; however, charge control agent (CCA) treated PVA/PVAc (skin/core) particles has lower zeta-potential than untreated PVA/PVAc particles. The zeta-potential (negative values) of the PVA/PVAc (skin/core) were enhanced in proportion to the increased concentration of CCA.

• Particle and aerosol research
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• v.14 no.3
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• pp.49-63
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• 2018

During the last decade, electrospray (ES) techniques have been used as potential methods for preparing of core-shell materials. Depending on the architecture of nozzle and design of devices, the ES techniques includes monoaxial, coaxial, multiple coaxial nozzle ES and microfluidic ES devices. ES operates based on a basic principle, in which a spray of monodisperse droplets is formed by dispensing an electrically conductive liquid through a capillary charged to a sufficiently high potential. In review of many recent research papers, we take a closer look at ES techniques and their applications for fabrication of core-shell materials. Several advantages of ES technique compared with other methods were emphasized and it may be regarded as a potential tool for fabrication of core-shell materials current and near future.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.229-235
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• 1970

Electrodeposition of lead peroxide on the graphite core was studied. The results are following; 1) At more noble potential than 1.6V vs. S.C.E. and lower temperature than $40^{\circ}C$, $PbO_2$ deposited current efficiency is increased but deposited layer falls off easily from graphite core. 2) Oxygen overvoltage of $PbO_2$ deposited layer on the graphite core is largely with increasing $PbO_2$ depositing anodic potential and with lowlying electrolytic temperature. 3) To obtain the $PbO_2$ deposited layer without falling off from the graphite core, it is necessary to change the electrolytic conditions, anodic potential and electrolytic temperature, in four stages successively.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.207-221
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• 2016

As greater numbers of fill dams and reservoirs become old, the risks of damage or embankment collapse increases. However, few studies have considered the deterioration and hazard classification of the internal core layers of fill dams. This study reports the results of geotechnical investigations of 13 earth-cored fill dams in Korea, based on no-water borehole drilling, Standard Penetration Test, and 2D and 3D electrical resistivity surveys along with in situ and laboratory testing. High-capacity no-water boring minimized core layer disturbance while providing continuous core sample recovery. The results allow the classification of potential hazards related to the existing core layers based on both visual inspection of the recovered samples and the results of engineering surveys and tests. Four types of potential hazard are classified: locally fluidized core with a high water content, rapid water inflow to a borehole, cores with granular materials, and relatively low stiffness of core. Among these, the locally fluidized core is the most critical hazard that requires remedial action because it is related to the potential internal flow path and internal erosion. The other three hazard types are of medium importance and require careful monitoring and regular inspection. Of note, there was no correlation between age and core deterioration. The results are expected to aid the safe management and potential upgrading of aging cored fill dams.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.50-54
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• 1999

We have measured the x-ray photoemission spectroscopy of cation deficient La0.970Mn0.970O3 as a function of temperature. Detailed results on the chemical shifts and changes in Mn 2p and Lp 3d core levels due to variation of temperature have been obtained. The Mn 2p 3/2 and 1/2 main peaks and La 3d core spectrum shift to lower binding energy levels with increasing temperature. This XPS behavior is correlated with the strength of localization of Mn3+. The Jahn-Teller effect due to Mn3+ besides the conventional random potential effects is likely to localize charge carriers in La-.970Mn0.970O3.

• Steel and Composite Structures
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• v.20 no.3
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• pp.513-543
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• 2016

Third order shear deformation theory is used to evaluate electro-elastic solution of a sandwich plate with considering functionally graded (FG) core and composite face sheets made of piezoelectric layers. The plate is resting on the Pasternak foundation and subjected to normal pressure. Short circuited condition is applied on the top and bottom of piezoelectric layers. The governing differential equations of the system can be derived using Hamilton's principle and Maxwell's equation. The Navier's type solution for a sandwich rectangular thick plate with all edges simply supported is used. The numerical results are presented in terms of varying the parameters of the problem such as two elastic foundation parameters, thickness ratio ($h_p/2h$), and power law index on the dimensionless deflection, critical buckling load, electric potential function, and the natural frequency of sandwich rectangular thick plate. The results show that the dimensionless natural frequency and critical buckling load diminish with an increase in the power law index, and vice versa for dimensionless deflection and electrical potential function, because of the sandwich thick plate with considering FG core becomes more flexible; while these results are reverse for thickness ratio.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.803-808
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• 2012

We have implemented two-component spin-orbit relativistic effective core potential (SOREP) methods in an all-electron relativistic program DIRAC. This extends the capacity of the two-component SOREP method to many ground and excited state calculations in a single program. As the test cases, geometries and energies of the small halogen molecules were studied. Several two-component methods are compared by using spin-orbit and scalar relativistic effective core potentials. For the $I_2$ molecule, excitation energies of low-lying excited states agree well with those from corresponding all-electron methods. Efficiencies in SOREP calculations enhanced by using symmetries are also discussed briefly.

• Journal of Magnetics
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• v.12 no.3
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• pp.113-117
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• 2007

Here we report a theoretical description of ferromagnetic vortex dynamics. Based on Thiele's formulation of the Landau-Lifshitz-Gilbert equation, the motion of the vortex core could be described by a function of the vortex core position. Under a parabolic potential generated in the circular magnetic patterns, the vortex core showed a circular rotation-namely the gyrotropic motion, which could be described by a 2-dimensional simple harmonic oscillator. The gyrotropic frequency and apparent damping constant were predicted and compared with the values obtained micromagnetic calculation.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.201-205
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• 2009

Triglyceride solid lipid with medium chain fatty acid, tricaprin (TC), was used as a core matrix of lipid nanoparticles (LN) to solubilize water-insoluble paclitaxel and enhance the stability of nanoparticles by immobilization of incorporated drug in the solid core during storage at low temperature. In the present study, TC-LN containing paclitaxel was prepared by hot melt homogenization method using TC as a core lipid and phospholipids as stabilizers. The particle size of TC-LN containing paclitaxel was less than 200 nm and its zeta potential was around -40 mV. Calorimetric analysis showed TC core could be solidified by freezing and thawing in the manufacturing process in which the hot dispersion should be prepared at elevated temperature and subsequently cooled to obtain solid lipid nanoparticles. The melting transition of TC core was observed at $27.5^{\circ}C$, which was lower than melting point of TC bulk. The particle size of TC-LN remained unchanged when kept at $4^{\circ}C$. Paclitaxel containing TC-LN showed comparable anticancer activity to the Cremophore ELbased paclitaxel formulation against human ovarian (OVCAR-3) and breast (MCF-7) cancer cell lines. Thus, lipid nanoparticles with medium chain solid lipid may have a potential as alternative delivery system for parenteral administration of paclitaxel.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.130-135
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• 2007

The mechanical characteristics of three types of core with two-dimensional isotropic patterns-triangular, hexagonal and starcell-were studied in applications to sandwich structures. The Young's modulus and shear modulus were calculated for the three core types in the direction normal to the faces. The compressive buckling strength and shear buckling strength were calculated by modeling each cell wall of the core as a plate under compressive or shear load. To verify this model, tests were conducted on scaled specimens to measures the compressive buckling strength of each core. The bending flexibilities of the three cores were also studied. Compliances for the three cores were measured using biaxial flexural tests. The three isotropic core patterns exhibited distinct characteristics. In the direction normal to the faces, all three cores had the same stiffness. However, the starcell core exhibited high flexibility compared to the other cores, indicating potential for application to curved sandwich structures.