• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 추계 총회 및 학술발표회
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• pp.59-62
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• 1998

1. 서론 : 막내부에서 물질전달을 설명하는 이론으로 현재 solution-diffusion model과 pore-flow model 두 가지가 있다. 이 중에서 흡착, 확산, 탈착의 3과정을 거치는 solution-diffusion model이 주로 사용되고 있다. 본 연구에서는 solution-diffusion model 에서 상호확산계수를 구하기 위해서 Vrentas-Duda식을 이용하여 자기확산계수를 구하고 Bearman식으로부터 상호확산계수를 구하는 과정을 UNIFAC-FV와 modified UNIFAC-FV을 이용하여 계산하였으며 Flory-Huggins식을 이용한 기존방법과 비교하였다.(생략)

• Computers and Concrete
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• 제7권5호
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• pp.421-435
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• 2010

This paper utilizes the modified Davis model and the mode coupling theory, as parts of the electrolyte solution theory, to investigate the diffusivity of the ion in concrete. Firstly, a computational model of the ion diffusion coefficient, which is associated with ion species, pore solution concentration, concrete mix parameters including water-cement ratio and cement volume fraction, and microstructure parameters such as the porosity and tortuosity, is proposed in the saturated concrete. Secondly, the experiments, on which the chloride diffusion coefficient is measured by the rapid chloride penetration test, have been carried out to investigate the validity of the proposed model. The results indicate that the chloride diffusion coefficient obtained by the proposed model is in agreement with the experimental result. Finally, numerical simulation has been completed to investigate the effects of the porosity, tortuosity, water-cement ratio, cement volume fraction and ion concentration in the pore solution on the ion diffusion coefficients. The results show that the ion diffusion coefficient in concrete increases with the porosity, water-cement ratio and cement volume fraction, while we see a decrease with the increasing of tortuosity. Meanwhile, the ion concentration produces more obvious effects on the diffusivity itself, but has almost no effects on the other ions.

• Korean Journal of Mathematics
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• 제20권1호
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• pp.47-60
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• 2012

We deal some analytic calculations for European option pricing by using the theory of elementary solution of generalized diffusion equation mainly.

• 한국환경과학회지
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• 제7권4호
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• pp.541-548
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• 1998

Aqueous phase adsorption of phenols by granular activated carbon was studied in a batch adsorption vessel. Adsorption Isotherms of phenol(Ph), p-chlorophenol(PCP) and p-nitrophenol (PNP) from aqueous solution on granular activated carbon have been obtained. The experimental data were analyzed by the surface and pore diffusion models. Both models could be applied to predict the adsorption phenomena. However, the pore diffusion model was slightly better than the surface diffusion model In representing the experimental data for the initial concentration changes. Therefore, the pore diffusion model was used to predict the change of operating variables such as the agitation speed and Particle size of adsorbent which have influence on the film resistance and intraparticle diffusion.

• Coupled systems mechanics
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• 제10권1호
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• pp.21-38
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• 2021

This work is an attempt to design a dynamic model for a non local bio-thermoelastic medium with diffusion. The system of governing equations are formulated in terms of displacement vector field, chemical potential and the tissue temperature in the context of non local dual phase lag (NL DPL) theories of heat conduction and mass diffusion. Based on this considered model, we study the fundamental solution and propagation of plane harmonic waves in tissues. In order to analyze the behavior of the NL DPL model, we construct basic theorem in the terms of elementary function which determine the existence of three longitudinal and one transverse wave. The effects of various parameters on the characteristics of waves i.e., phase velocity and attenuation coefficients are elaborated by plotting various figures of physical quantities in the later part of the paper.

• 반도체디스플레이기술학회지
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• 제3권3호
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• pp.19-21
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• 2004

This paper presents a 3-dimensional diffusion simulation with adaptive solution strategy. The developed diffusion simulator VLSIDIF-3 was designed to re-refine areas. Refine scheme was calculated by the difference of doping concentration between any of two nodes. Each element is greater than tolerance and redo diffusion process until error is tolerable. Numerical experiment in low doping diffusion problem showed that this adaptive solution strategy is very efficient in both memory and time, and expected this scheme would be more powerful in complex diffusion model.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2004년도 춘계학술대회 발표 논문집
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• pp.55-58
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• 2004

This paper presents a 3-dimensional diffusion simulation with adaptive solution strategy. The developed diffusion simulator VLSIDIF-3 was designed to re-refine areas where difference of doping concentration between any of two nodes of each element is greater than tolerance and redo diffusion process until error is tolerable. Numerical experiment in low doping diffusion problem showed that this adaptive solution strategy is very efficient in both memory and time, and expected this scheme would be more powerful in complex diffusion model.

• 대한기계학회논문집B
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• 제34권2호
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• pp.99-103
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• 2010

다공성 매질상에서 유체와 용질의 이동은 Mobile zone과 Immobile zone으로 분리해서 분석하는 Mobile-Immobile Zone Model을 이용하여 쉽게 현상을 구현할 수 있었으나 본 연구에서는 2차원 4각형태의 pore 상에서 확산주도영역(Immobile zone)으로 들어가고 나오는 용질의 확산에 관한 새로운 Analytic solution을 유도하여 기존 MIM Zone model과 비교 분석하였다. 새롭게 유도된 Analytic solution은 기존의 MIM model 과 비교했을때 충분히 오랜시간이 경과한 후에는 해의 일치를 보이지만 MIM model의 경우 초기 농도값이 주입된 실제 농도보다 약 20 % 낮게 나타난다. Mass-transfer 계수, $\alpha$는 일반적으로 시간의 흐름에 따라 감소하게 되는데 일정 시간이 경과하게 되면 안정화 되고 일정함을 유지하며 그 시간은 무차원으로 약 ${\tau}_0=0.15$이다. 또한 $\alpha$는 분자확산과 비례하며 Immobile 영역의 깊이와 반비례하는 반면 작은 시간이 경과한 후에는 시간에 종속되어진다.

• 한국경영과학회지
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• 제37권2호
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• pp.113-125
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• 2012

The logistic model and the Bass model have diverse names and formulae in diffusion theory. This diversity makes users or readers confused while it also contributes to the flexibility of modeling. The method of handling the integration constant, which is generated in process of deriving the closed form solution of the differential equation for a diffusion model, results in two different 'actual' models. We rename the actual four models and propose the usage of the models with respect to the purpose of model applications. The application purpose would be the explanation of historical diffusion pattern or the forecasting of future demand. Empirical validation with 86 historical diffusion data shows that misuse of the models can draw improper conclusions for the explanation of historical diffusion pattern.

• 멤브레인
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• 제14권1호
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• pp.75-84
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• 2004

폴리아미드계 역삼투 분리막의 투과성능을 비교하기 위하여 NaCl과 NaOCl을 함유하는 혼합용액을 공급수로 사용하여 연속운전과 단속운전 하에서 실험하여 보았다. 이 결과를 가지고 막 이동 모델의 선택적 적용이 가능함을 제시하고자 하였으며 투과 성능 분석 결과, 용액 확산 모델과 선흡착-모세관이동 모델이 운전 모드에 따라 상대적으로 유용함을 볼수 있었다. 연속 운전에서는 선흡착-모세관이동 모델을, 단속 운전에서는 용액 확산 모델을 따름을 알 수 있었다 NaOCl에 의한 표면 변화를 SEM 사진을 통하여 확인 할 수 있었다. 연속운전 후의 막은 염소 투과 결과 표면에서 부분적인 ridge and valley 구조가 나타났으며 단속 운전 후의 막은 표면 전반에서 변성이 일어난 것을 볼 수 있었다.