• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.269-272
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• 2006

Chloride ion diffusion is the most important thing of occuring deterioration in RC structure. So it is important to decide the precise chloride ion diffusion coefficient in order to predict the durability life in RC structure. The purpose of this study is to analyze the established data, which are restricted by chloride diffusion coefficient, and to calculate chloride ion diffusion coefficient using RCPT test. To examine the prediction of the concrete structure durability by an FEM analysis and the chloride diffusion coefficient as a variable. Each surface finishing materials were effective on the increment of chloride penetration resistance, but showed a little different effect depending on the type of surface finishing material.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.280-280
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• 2012

We examined ammonia diffusion on the surface of amorphous ice film through the measurement of decreasing residual quantity of $NH_3$ molecules compared to $H_2O$. The populations of $NH_3$ molecules on the surface of amorphous ice were monitored by using the techniques of temperature programmed reactive ion scattering (TPRIS) method. The ratio of intensity between ammonia and water was examined as a function of time at controlled temperature. When ammonia molecules were externally added onto an ice film at a temperature of 80 K, ammonia coverage with regard to ice was 0.12-0.16 ML. The intensity of ammonia molecules on the surface of ice decreased as time increased and the extent of decreased intensity of ammonia increased as controlled temperature increased. Moreover, energy barrier was estimated to be $51kJmol^{-1}$ on amorphous ice film. The results of the experiment indicate that ammonia molecules have a property of vertical diffusion into amorphous ice and the energy barrier of ammonia diffusion into bulk of ice is higher than that of hydrogen bonding.

• Journal of the Korean Vacuum Society
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• v.8 no.3A
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• pp.181-186
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• 1999

The diffusion of oxygen atoms on tungsten (110) surface is studied by comparison of experiment results and recent calculations. It has been suggested that the thermodynamic factor which is inversely proportional to be compressibility has strong temperature dependence which may cause non-Arrhenius behavior of diffusion coefficient. Recent experiments, however, indicate effectively no temperature dependence of this factor and support the view that non-Arrhenius behavior originates from the dynamic factor rather than the thermodynamic factor. Discrepancies in coverage dependence of physical quantities between theory and experiment are discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.372-375
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• 2006

SOFC is a high temperature fuelcell with many advantages, but it also have several demerits. One of the Issues is cathode poisoning of Cr coming from stainless steel interconnects. Diffusion process of Cr evaporated from the surface of interconnect steel was calculated by using CFD technique to understand factors for Cr deposition. It has been cleared that factors concerned in Cr deposition and how they affect Cr deposition. Major variables for Cr deposit ion are diffusion coefficient, air velocity and temperature If diffusion coefficient decreases, Cr concentration increases in the air but decreases on the cathode surface. Increasing in air velocity, Cr concentration decreases in the air and on the cathode surface. Increase in temperature leads to rising Cr concentration on the cathode surface because of diffusion coefficient increment.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.77-86
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• 2000

In order to observe the pattern forming of copper plate and chemical corrosion reaction, a study on the effect of the process parameters on the formation of micro-pattern by a photochemical etching of copper plate was carried out. The results are as follows : 1) Etching rate increases as the concentration of etchant increases under the regular condition of the temperature by the increasing of diffusion rate to surface. 2) Etching rate increases as the temperature of etchant increases by the fast acting of the material delivery of diffusion to surface under the regular condition of concentration. 3) It was found that etching speed increases as the material delivery of convection rising increased when the aeration speed of etchant increases. This result was from the fact acted by the material delivery of convection rising rather than material delivery of diffusion to the surface.

• Journal of the Korean institute of surface engineering
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• v.24 no.3
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• pp.144-150
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• 1991

The stainless steel 304 oxidized at $70^{\circ}C$ in 2.5M CrO3/5.0M H2SO4 solution and at $200^{\circ}C$ , $300^{\circ}C$, and $400^{\circ}C$ in the air are analyzed with X-ray Photoelectron Spectroscopy (XPS) to obtain depth composition profile of the surface region. It is confirmed that the surface region has a quite different composition from that of the bulk. This is due to a difference in the outward diffusion rates of the oxidized species in the surface region. The order of diffusion rates is Fe > Cr > Ni in the experimental temperature range. In spite of the inferior rate of diffusion, Cr is enriched in the surface when it is oxidized in the CrO3/H2SO4 solution. This is due to preferential dissolution of oxidized Fe.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.233-236
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• 2004

The purpose of this paper is to evaluate performance on reducing the chloride diffusion of surface treatment systems with elapsed time, treatment thickness, treatment frequency, and the types of surface treatment - coating, penetrator, and both all. Based on this paper, the guideline to applicate surface treatment systems will be established and comprehended how effective the resistance of chloride diffusion is. The selection of surface treatment materials and thickness to acquire service life of target will be possible. It is also expected to select optimum surface treatment system groups to resist chloride diffusion effectively and to estimate increased service life as the effect of durability enhancement.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.475-480
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• 2001

Diffusion of Cu into the low-k para-xylene based plasma polymer (pXPP) thin films deposited by plasma-enhanced chemical vapor deposition using the para-xylene precursor was comparatively measured using various methods. Cu layer was deposited on the surfaces of pXPPs treated by $N_2$ plasma generated in a magnetically enhanced inductively coupled plasma reactor. Diffusion characteristics of Cu into pXPPs were measured using Rutherford backscattering spectroscopy (RBS), secondary ion mass spectroscopy (SIMS), cross-sectional transmission electron microscopy (XTEM), and current-voltage (I-V) measurements for the vacuum-annealed Cu/pXPPs for 1 hour at $450^{\circ}C$ and were compared. The results showed a correlation between the I-V measurement and SIMS data are correlated and have a sensitivity enough to evaluate the dielectric properties but the RBS or XTEM measurements are not sufficient to conclude the electrical properties of low-k dielectrics with Cu in the film bulk. The additional results indicate that the pXPP layers are quite resistant to Cu diffusion at the annealing temperature of $450^{\circ}C$ compared to the other previously reported organic low-k materials.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.65-72
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• 2013

Adsorption of melamine was examined using columns packed with granular activated carbon (GAC). Raw GAC was sieved with 20, 40, 60 and 80 mesh to determine the influence of adsorbent particle size on reaction and diffusion. The mass ratio of the adsorption capacity of GAC for melamine ranged from 9.19 to 11.06%, and adsorption rates increased with decreasing particle size within this range. Rate constants between 3.295 ~ 4.799 $min^{-1}$ were obtained using a pseudofirst-order equation that was used to determine adsorption kinetics. A surface diffusion model was adapted to take into account the unsteady-state equation of a spherical adsorbent by converting the surface concentration from a constant to a variable governed by a dispersion equation. The calculated values were fit with the experimental results by using the diffusion coefficients as regression parameters. The modified equation exhibited a more precise agreement with respect to the sum of the absolute error (SAE).

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.83-91
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• 2015

With varying conditions of concrete surface, induced chloride contents are changed and this is a key parameter for steel corrosion and service life in RC (Reinforced Concrete) structures. Many surface enhancement techniques using impregnation have been developed, however the evaluation techniques for chloride behavior through doubly layered media and time-dependent diffusion are rarely proposed. This paper presents an analysis technique considering double-layer concrete and time-dependent diffusion behavior, and the results are compared with those from the previous test results through reverse analysis. The chloride profiles from the surface-impregnated concrete exposed to atmospheric, tidal, submerged zone for 2 years are adopted. Furthermore surface chloride contents and diffusion coefficients are obtained, and are compared with those from Life365. Through consideration of time effect, the relative error decreases from 0.28 to 0.20 in atmospheric, 0.29 to 0.11 in tidal, and 0.54 to 0.40 in submerged zone, respectively, which shows more reasonable results. Utilizing the diffusion coefficients from Life365, relative errors increases and it needs deeper penetration depth (e) and lower diffusion coefficient ratio ($D_1/D_2$) due to higher diffusion coefficient.