• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.31-38
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• 2000

Anti-corrosion behaviour of rebar embedded in cement mortar containing chloride ions was investigated by electrochemical chloride extraction(ECE). $43\%$ of the initial chloride ions of the cement mortar was fixed to Friedel salts and the soluble chloride ions were successfully extracted by ECE method. Concentration profiles of the chloride ions were estimated by Fick's 2nd law with time and depth, and it was close to the real value. The corrosion potential increased to anodic direction after ECE test, and the corrosion of rebar was reduced as a result of AC impedance spectroscopy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.625-629
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• 2015

In this study, we develop a prognostic method of assessing the stator windings of power generators against water absorption through statistical data analysis and degradation modeling. The 42 windings of the generator are divided into two groups: the absorption and normal groups. A degradation model of a winding is constructed using Fick's second law to predict the level of absorption. By analyzing data from the normal group, we can determine the distribution of the data of normal windings. The health index of a winding is estimated using the directional Mahalanobis distance (DMD) method. Finally, the probability distributions of the failure time of the windings are determined.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.114-122
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• 2016

Concrete is cost-benefit and high-durable construction material, however durability problem can be caused due to steel corrosion under chloride attack. Recently deicing salt has been widely spread in snowing season, which accelerates micro-cracks and scaling in surface concrete and the melted deicing salt causes corrosion in embedded steel. The previous governing equation of Fick's 2nd Law cannot evaluate the deteriorated surface concrete so that another technique is needed for the surface effect. This paper presents chloride penetration analysis technique for concrete subjected to deicing salt utilizing multi-layer diffusion model and time-dependent diffusion behavior. For the work, field investigation results of concrete pavement exposed deicing salt for 18 years are adopted. Through reverse analysis, deteriorated depth and increased diffusion coefficient in the depth are evaluated, which shows 12.5~15.0mm of deteriorated depth and increased diffusion coefficient by 2.0 times. The proposed technique can be effectively applied to concrete with two different diffusion coefficients considering enhanced or deteriorated surface conditions.

• Korean Journal of Food Science and Technology
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• v.18 no.1
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• pp.61-65
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• 1986

This study was performed to examine the drying characteristics of apples at various drying conditions. Air velocity has no effect on the drying rate except the constant rate period. In this experiment the diffusion coefficients of moisture in the apple tissue were in the range of $1.1470-2.2148{\times}10cm^2/sec$. As a result of balance of heat and mass transfer during the falling rate period. an empirical equation based on Fick's law was obtained as follows; $log{\Delta}t\;=\;log\;t_o\;-\;D{\frac{{\pi}^2{\theta}}{4d.}}$ This equation can be used to calculate the temperature of apples during the falling rate period, provided the diffusion coefficients of apple are known. The experimental values of the internal moisture distribution during apple dehydration were nearly in accord with the theoretical values.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.67-74
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• 2015

RC (Reinforced Concrete) structures are considered as cost-benefit and durable however performances of structural safety and durability are degraded due to steel corrosion. Service life in RC structure is differently evaluated due to different local environmental conditions even if it is exposed to the same chloride attack. In the paper, 25 concrete cores from field investigation are obtained from 4 RC columns with duration of 3.5~4.5 years exposed to sea water. Through total chloride content measurement, surface chloride contents and apparent diffusion coefficients are evaluated. Service life of the target structure is estimated through deterministic method based on Fick's $2^{nd}$ Law and probabilistic method based on durability failure probability, respectively. Probability method is evaluated to be more conservative and relatively decreased service life is evaluated in tidal zone and splash zone over 40.0 m. Chloride penetration behavior with coring location from sea level and the present limitations of durability design method are investigated in the paper.

• The Korean Journal of Food And Nutrition
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• v.10 no.4
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• pp.462-467
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• 1997

The DIS process(dewatering and impregnation soaking process) are using for dewatering of food materials at room temperature. And the DIS process are resulted in diffusion process as well as dewatering phenomena. During the DIS process, plasmolysis or cytorrhysis was happened by according to solute size. A tissue state of food material was very important variables for movement of water or solute, and running conditions are important for dewatering and impregnation. And models for DIS process were fundamentally given by Fick's law at unsteady state or mass balance. For example, Bicompartmental Model was given for quantification of water loss and solid gain.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.1-11
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• 2003

A mathematical model was proposed to analyze the oxygen diffusion reaching the cornea through the tear layers and contact lens based on Fick's law and the principle of continuity of the diffusion flux through the each layers. The model predicts how the parameters such as the thickness of tear layer on the cornea, both the Dk and thickness of contact lenses etc., affect the oxygen tension at cornea and oxygen flux entering the cornea. It is found that either too flat or too tightly fitted contact lenses can cause the oxygen deficiency inside the periphery of the cornea because of the reduction of oxygen flux resulted from too thickened tear layer.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.332-339
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• 2017

In the case of aged structures, the information of the structure is often lost after the completion of construction, and there is a great difficulty in predicting the durability life of the structure due to the lack of information on concrete formulations. In this study, the durability of concrete specimens was evaluated by various field and indoor test methods based on the core specimens collected from the field, and the durability life of the concrete structures was predicted by using the FEM analysis technique.As a result, the neutralization rate coefficient was $5.38E-6(cm^2/day)$ and the rate of progress was low. And the possibility of complex deterioration due to carbonation and salting was found to be very low.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1333-1337
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• 2002

A significant fraction of nutrients, such as nitrogen and phosphorus released from sediment are utilized by primary production in the shallow water of coast and lake. The purpose of this study is to introduce the mechanism of nutrients release from sediment and to introduce the methods of the measurement of nutrient released from sediment. One approach is to calculate nutrients released from sediment by a concentration gradient between sediment pore waters and overlying water based on the Fick's law. The other approaches of measurement are the undisturbed sediment core experiments and measurement of nutrient released from sediment by the in situ chamber equipment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.40-46
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• 1984

The extraction ratio of oil using solvent from the muscle of sardine, Sardinops melanosticta, was studied. The results were critically evaluated in the light of the theory of oil diffusion in a porous solid model. In addition the effect of temperature and moisture on the extraction rate was examined. Sardine muscle was prepared in a manner to meet the conditions required by the diffusion theory from Fick's law. The results of the model were well coincidenced to the theory derived from Fick's law. Diffusion constants at the direction to muscle fiber($D_1$) and at direction perpendicular to fiber($D_2=D_3$) when extracted at $45^{\circ}C$ were $8.16{\times}10^{-8}cm^2/sec\;and\;4.12{\times}10^{-8}cm^2/sec$, respectivly. The extraction rate was linearly propotional to absolute temperature(T) by eleventh power under the constant condition of moisture contents and muscle size. A comparison of the experiments with the highest($74.22\%$) and the lowest ($32.48\%$) moisture indicated that difference of $1\%$ in moisture contents caused to change the slope(K) of the extraction curve $0.53{\times}10^{-6}sec^{-1}$ approximately.