• Computers and Concrete
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• 제14권3호
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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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• 제12권4호
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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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• 제7권4호
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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.

• 한국신뢰성학회지:신뢰성응용연구
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• 제12권3호
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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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• 제19권12호
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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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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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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.

• 공업화학
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• 제35권1호
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• pp.48-53
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• 2024

전기화학 기반의 SEI 성장 모델을 이용하여 리튬이온 배터리의 캘린더 노화 및 장기 수명을 예측하였다. 네 가지 유형의 장기 SEI 성장 모델(용매 확산 제한 모델, 전자 이동 제한 모델, 리튬-간극 확산 제한 모델, 반응 제한 모델)을 적용하여 수치해석이 이루어졌고, 캘린더 에이징 동안의 용량 감소와 리튬 재고 손실을 계산하였다. 수치해석 결과, 전자 이동 제한 모델과 리튬-간극 확산 제한 모델이 낮은 용량 감소를 보였으며, 용매 확산 제한 모델과 반응 제한 모델은 10년이내에 80%의 용량 감소를 보였다. 캘린더 노화 중 저온 보관 시 SEI의 성장을 저하시켜 용량 감소가 적었다. 사이클링 중 C-rate가 증가할수록 SEI 두께 증가로 수명 하락이 크게 나타났으나 그 차이는 크지 않았다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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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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• 제17권2호
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• pp.49-59
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• 1992

이온 또는 착화된 상태의 방사성핵종의 이동에 대한 착화제의 영향을 조사하기 위하여 새로운 모델이 제시되었다. 착화된 방사성핵종의 이동거동은 착화제와 착화된 방사성핵종의 열화를 포함하는 대류-확산 이동방정식에 의해 해석되었다. 이 수학적 모델은 해석적인 방법 에 의해 구해졌으며 지연요소를 조사함으로써 분석되었다. 계산결과들은 감소된 지연요소에 의해 착화된 방사성핵종의 이동속도가 이온형태의 방사성핵종보다 매우 빠름을 보여주었다. 따라서 원자력발전소로부터의 착화제의 발생과 환경으로의 유출을 감소시킬 수 있는 새로운 구제책이 필요하다고 하겠다.

• Advances in concrete construction
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• 제1권3호
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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.