• Computers and Concrete
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• v.14 no.3
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• pp.263-277
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• 2014

This study investigated four electric field configurations of two-dimensional accelerate lithium migration technique (ALMT), including line-to-line, plane-to-line, contour-to-line and plane-to-plane, and analyzed the ion migration behavior and efficiency. It was found that the free ion distribution diagram and voltage distribution diagram were similar, and ions migrated in the power line direction. The electrode modules were used for the mortar specimen with w/c ratio of 0.5. The effectively processed areas accounted for 14.1%, 39.0%, 49.4% and 51.4% of total area respectively on Day 28. Larger electrode area was more advantageous to ion migration. In addition, it was proved that the two-dimensional electric field could be divided into different equifield line active regions, and regarded as affected by one-dimensional electric field, and the ion migration results in various equifield line active regions were predicted by using the duration analysis method based on the theoretical model of ion migration obtained from one-dimensional test.

• Computers and Concrete
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• v.12 no.4
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• pp.431-442
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• 2013

This study attempted to find a proper method applicable to simulating practical equifield lines of two-dimensional Accelerate Lithium Migration Technique (ALMT), and evaluate the feasibility of using the theoretical ion migration model of one-dimensional ALMT to predict the ion migration behavior of two-dimensional ALMT. The result showed that the electrolyte or carbon plate can be used as matrix to draw equifield line graph similar to that by using mortar as matrix. Using electrolyte electrode module for simulation has advantages of simple production, easy measurement, rapidness, and economy. The electrolyte module can be used to simulate the equifield line distribution diagram in practical two-dimensional electrode configuration firstly. Then, several equifield line zones were marked, and several subzones under one-dimensional ALMT were separated from various equifield line zones. The theoretical free content distribution of alkali in concrete under two-dimensional electric field effect could be obtained from duration analysis.

• Bulletin of the Korean Chemical Society
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• v.7 no.4
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• pp.279-282
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• 1986

The MNDO calculations were performed in order to investigate the gas-phase reaction mechanism of 2-propene-1-al oxide, as a model compound of dypnone oxide(1,3-diphenyl-2-butene-1-one oxide) with the chloride ion. Optimized geometries and heats of formation for two probable concerted pathways, CHO and H migration, were determined and their activation energies were obtained. MO results show that although the formyl migration is thermodynamically more favorable than the hydride migration, the latter kinetically predominates over the formyl migration, which is contrary to the established migrating preferences. It is concluded that the hydride migratory propensity is catalyzed by the chloride ion by reducing the capability of the carbonyl ${\pi}$ bond to participate in the migration.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.153-163
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• 2012

Recently, as a electronic components are becoming more high-density, so that electronic circuits have smaller pitches between the leads and are more vulnerable to insulation failure. And the reliability of electric insulation has become an ever important issue as device contact pitches and print patterns shrink. Ion migration occurs in highly humid environment as voltage is applied to an installed print circuit. Under highly humid and voltage applied circumstances, electronic components respond to applied voltages by electrochemical ionization of metals, and a conducting filament forms between the anode and cathode across a nonmetallic medium. This leads to short-circuit failure of the electronic component. In thesis, we study acceleration test of ion migration in FR-4 PCB plated with Sn. Voltage applied test of FR-4 PCB circuits plated with Sn was tested in the temperature and humidity environments. As a result of this test, equation of acceleration model was derived.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1347-1350
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• 1998

The equivalent conductances for tetraethylammonium perchlorate (TEAP), tetrabutylammonium perchlorate (TBAP), tetrahexylammonium perchlorate (THAP), and tetradodecylammonium perchlorate (TDDAP) were measured in pyridine (Py) at 25 ℃. The measured data have been analyzed by Onsager conductance theory. From Kohirausch's law of independent migration of ion, the limiting ionic conductances of tetraalkylammonium ions were determined using the limiting ionic conductance of perchlorate cited from reference. Using those and viscosity of pyridine, the Stokes and hydrodynamic radii of tetraethylammonium, tetrabutylammonium, tetrahexylammonium, and tetradodechylammonium ions were calculated. And, the salvation numbers of corresponding ions were also calculated using the hydrodynamic and crystallographic radii and the volume of one pyridine molecule. From those results, the model of salvation for those ions was extracted by comparison with the model for ion salvation. And the electrostatic Gibbs free energy (ΔGel) fitted for our salvation model was calculated. Those of corresponding ions in pyridine at 25 ℃ also increased with increasing radii of tetraalkylammonium ions. This trend of ΔGel was explained by the different ion-solvent interaction between tetraalkylammonium ion and pyridine.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.629-636
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• 2003

The retardation of heavy metals in a mixture of fly ash and bentonite was studied as a potential barrier material for a landfill. Column tests were conducted using synthetic leachate having 100 mg/L and 50 mg/L of lead (Pb) and cadmium (Cd), respectively. Results indicated that the mixture had obvious retardation ability for heavy metals. To investigate the retardation factor caused by adsorption, batch adsorption tests were conducted at various concentrations. Test results were correlated with both Langmuir and Freundlich isotherms. The adsorption of the lead ion was applicable to the Langmuir isotherm and the adsorption of the cadmium ion was applicable to the Freundlich isotherm. In addition, based on experimental results, the migration characteristics of heavy metals through the bed of fly ash and bentonite mixture were investigated using the PHREEQC, a reactive transport model, under the real conditions of the landfill liner.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.48-53
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• 2024

We predicted the calendar aging and long-term lifetime of lithium-ion batteries using an electrochemical-based SEI growth model. Numerical simulation was carried out employing the four different long-term SEI growth models (i.e., solvent diffusion limited model, electron migration limited model, Li-interstitial diffusion limited model, reaction limited model), and we calculated the capacity fade and loss of lithium inventory during calendar aging. The result showed that the electron migration limited model and Li-interstitial diffusion limited model showed lower capacity fade, while the solvent diffusion limited model and reaction limited model reached 80% of capacity fade within 10 years. During calendar aging, the lower storage temperature showed less capacity fade due to the hindrance of SEI growth rate. During cycling, the higher C-rate showed a shorter life cycle; however, the differences were not significant.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.97-103
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• 2001

The effects of the electrohydrodynamic (EHD) flow and turbulent diffusion on the collection efficiency of a model ESP composed of the plates with a cavity were studied through numerical computation. The electric field and ion space charge density were calculated by the Poisson equation of the electrical potential and the current continuity equation. The EHD flow field was solved by the continuity and momentum equations of the gas phase including the electrical body force induced by the movement of ions under the electric field. The RNG $k-{\varepsilon}$ model was used to analyze the turbulent flow. The particle concentration distribution was calculated from the convective diffusion equation of the particle phase. As the ion space charge increased, the particulate collection efficiency increased because the electrical potential increased over the entire domain in the ESP. The collection efficiency decreased and then increased, i.e. had a minimum value, as the EHD circulating flow became stronger when the electrical migration velocity of the charged particle was low. However, the collection efficiency decreased with the stronger EHD flow when the electrical migration of the particle was higher relatively. The collection efficiency of the model ESP increased as the turbulent diffusivity of the particle increased when the electrical migration velocity of the particle was low. However, the collection efficiency decreased for increasing the turbulent diffusivity when the electrical migration of the particle was higher relatively.

• Journal of Radiation Protection and Research
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• v.17 no.2
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• pp.49-59
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• 1992

A new model was developed in order to investigate the effects of chelating agents on the migration of a radionuclide in the form of ion or chelate. The migration behavior of the chelated radionuclide was analyzed by formulating a convective-dispersion transport equation which included a degradation of chelating agent and chelated radionuclide. The mathematical model was analytically solved and checked with the existing retardation factor. The results show that the migration velocity of the chelated radionuclide was much faster than the ionic one due to the decreased retardation. Therefore, it was concluded that a new remedial action should be developed to reduce the generation and release of chelating agents from the nuclear power plant into the environment.

• Advances in concrete construction
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• v.1 no.3
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• pp.239-252
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• 2013

Mortar microstructure is considered as a three-phase composite material, which is cement paste, fine aggregate and interfacial transition zone. Interfacial transition zone is the weakest link between the cement paste and fine aggregate, so it has a significant role to determine the properties of cementitious composites. In this study, specimens (w/c = 0.35, 0.45, 0.55) with various volume fractions of fine aggregate ($V_f$ = 0, 0.1, 0.2, 0.3 and 0.4) were cast and tested. To predict the equivalent migration coefficient ($M_e$) and migration coefficient of interfacial transition zone ($M_{itz}$), double-inclusion method and Mori-Tanaka theory were used to estimate. There are two stages to estimate and calculate the thickness of interfacial transition zone (h) and migration coefficient of interfacial transition zone ($M_{itz}$). The first stage, the data of experimental chloride ion migration coefficient ($M_s$) was used to calculate the equivalent migration coefficient of fine aggregate with interfacial transition zone ($M_e$) by Mori-Tanaka theory. The second stage, the thickness of interfacial transition zone (h) and migration coefficient of interfacial transition zone ($M_{itz}$) was calculated by Hori and Nemat-Nasser's double inclusion model. Between the theoretical and experimental data a comparison was conducted to investigate the behavior of interfacial transition zone in mortar and the effect of interfacial transition zone on the chloride migration coefficient, the results indicated that the numerical simulations is derived to the $M_{itz}/M_m$ ratio is 2.11~8.28. Additionally, thickness of interfacial transition zone is predicted from $10{\mu}m$, 60 to $80{\mu}m$, 70 to $100{\mu}m$ and 90 to $130{\mu}m$ for SM30, M35, M45 and M55, respectively.