• Computers and Concrete
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• 제17권1호
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• pp.53-66
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• 2016

Currently, most of the investigations on chloride diffusion were based on the experiments and simulations concerning single cation type chlorides. Chloride diffusion associated with dual or multi cation types was rarely studied. In this paper, several groups of diffusion experiments are conducted using chloride solutions containing single, dual and multi cation types. A multi-ionic model is also proposed to simulate the chloride diffusion behavior in the experimental tests. The MATLAB software is used to numerically solve the nonlinear PDEs in the multi-ionic model. The experimental and simulated results show that the chloride diffusion behavior associated with different cation types is significantly different. When the single cation type chlorides are adopted, it is found that the bound rates of chloride ions combined with divalent cations are greater than those combined with monovalent cations. When the dual/multi cation type chlorides are adopted, the chloride bound rates increase with the $Ca^{2+}/Mg^{2+}$ percentage in the source solutions. This evidence indicates that the divalent cations would markedly enhance the chloride binding capacity and reduce the chloride diffusivity. Moreover, on the basis of the analysis, it is also found that the complicated cation types in source solutions are beneficial to reducing the chloride diffusivity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.30-33
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• 2004

Shallow p+-n junctions were formed by low-energy ion implantation and dual-step annealing processes The dopant implantation was performed into the crystalline substrates using $BF_2$ ions. The annealing was performed with a rapid thermal processor and a furnace. FA+RTA annealing sequence exhibited better junction characteristics than RTA+FA thermal cycle from the viewpoint of junction depth. A new simulator is designed to model boron diffusion in silicon, which is especially useful for analyzing the annealing process subsequent to ion implantation. The model which is used in this simulator takes into account nonequilibrium diffusion, reactions of point defects, and defect-dopant pairs considering their charge states, and the dopant inactivation by introducing a boron clustering reaction. Using a resonable parameter values, the simulator covers not only the equilibrium diffusion conditions but also the nonequilibrium post-implantation diffusion. Using initial conditions and boundary conditions, coupled diffusion equation is solved successfully. The simulator reproduced experimental data successfully.

• 경영과학
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• 제19권2호
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• pp.125-137
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• 2002

The telecommunications market is expanding rapidly and becoming more substitutive. In this environment, demand forecasting is very difficult, yet important for both practitioners and researchers. in this paper, we adopt the modeling approach proposed dy Jun and Park ［6］. The basic premise is that demand patterns result from choice behavior, where customers choose a product to maximize their utility. We apply a choice-based substitutive diffusion model to the Korean mobile telecommunication service market where digital service has completely replaced analog service. In comparison with Bass-type multigeneration models. our model provides superior fitting and forecasting performance. The choice-based model is useful in that it enables the description of such complicated environments and provides the flexibility to include marketing mix variables such as price and advertising in the regression analysis.

• Journal of applied mathematics & informatics
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• 제31권5_6호
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• pp.695-709
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• 2013

Calcium is well known role for signal transduction in a neuron cell. Various processes and parameters modulate the intracellular calcium signaling process. A number of experimental and theoretical attempts are reported in the literature for study of calcium signaling in neuron cells. But still the role of various processes, components and parameters involved in calcium signaling is still not well understood. In this paper an attempt has been made to develop two dimensional finite element model to study calcium diffusion in neuron cells. The JRyR, JSERCA and JLeak, the exogenous buffers like EGTA and BAPTA, and diffusion coefficients have been incorporated in the model. Appropriate boundary conditions have been framed. Triangular ring elements have been employed to discretized the region. The effect of these parameters on calcium diffusion has been studied with the help of numerical results.

• 인터넷정보학회논문지
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• 제7권1호
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• pp.39-47
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• 2006

MD4를 기반으로 하는 MDx계열 해쉬 함수는 입력 워드의 치환, 순환 시프트 변수의 연쇄, 비선형 함수 등을 이용하여 구성된다. 그러나, 그 구성 방법에 대한 이론적, 실험적 배경은 알려져 있지 않고, 평가를 위한 일반적인 모델도 알려져 있지 않다. 본 논문에서는 해쉬 함수의 설계와 평가를 위하여 해쉬 함수를 일반화하기 위한 근사 모델을 제안하고, MD5에 근사모델을 적용하여 입력 차분의 확산을 고찰하였다. 그 결과, MD5의 약점이 완전 확산을 제공하지 않는데 있다는 것을 확인하였다. 제안된 근사 모델에서 완전 확산을 제공하기 위하여 해쉬 함수 내에 여러 가지 연쇄 패턴을 이용하는 다중 연쇄 패턴을 제안하고, 여분의 계산과 메모리 없이 완전 확산을 제공함을 MD5를 이용한 실험을 통하여 보이고, 그 차분 특성이 갖는 확률이 MD5보다 작음을 증명하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권5호
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• pp.360-364
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• 2009

블로그 월드에서의 정보의 파급에 대한 기존의 연구들은 블로그들 간에 명시적 관계를 설정하고, 정보가 파급되는 요인으로서 이 관계를 통해서 발생하는 입소문 효과만을 고려하였다. 그러나 본 연구자들의 선행 연구 결과에 따르면 블로그 월드에서 실제 발생하는 정보의 파급 현상들의 약 85%는 비명시적 관계를 통해서 발생한 것이다. 따라서 본 논문에서는 명시적 관계, 비명시적 관계를 통한 정보의 파급을 함께 고려하여 이들 관계를 통한 정보의 파급 현상을 효과적으로 분석할 수 있는 새로운 정보 파급 모델을 제안한다. 또한, 실제 블로그 연결망에서 제안하는 기법과 기존의 기법을 이용하여 정보의 파급 분석의 수행 성능을 비교함으로써 제안하는 기법의 우수성을 검증한다.

• 방송공학회논문지
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• 제10권3호
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• pp.383-391
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• 2005

본 논문은 블록DCT(Discrete Cosine Transform) 기반의 영상 압축 과정에서 발생하는 블록효과(block artifact)를 제거하기 위해 ALM(Alvarez, Lions, and Morel) 확산 모델에 기반을 둔 새로운 이방성 확산(anisotropic diffusion)을 제안한다. 등방성 확산은 평탄 영역에 나타나는 블록 경계를 제거하는 역할을 하는 반면, 이방성 확산은 윤곽선 영역이나 텍스쳐 영역을 보존하는 역할을 하기 때문에, 제안된 확산 모델은 블록 효과를 제거하면서 윤곽선(edge)을 보존하기 위해 등방성 확산(isotropic diffusion)과 이방성 확산의 비율을 제어하는 확산비율 조절 매개 변수(RCP : rate control parameter)가 제안 되었다. 또한, 텍스쳐 영역의 과도한 평탄화를 막기 위해 속도 매개 변수(SAP : speed control parameter)를 고안하였으며, 이는 텍스쳐 영역의 확산 속도를 감소시기는 역할을 한다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.144-147
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• 2003

It is important to understand the process of technology diffusion among end users for effectively implementing adoption and coping with frequent changes in the environment. Previous studies indicate that information and communication technology (ICT) adoption is affected by innovation influence such as usefulness, ease of use and self-efficacy. Most of these studies, however, bypassed imitation influence such as subjective norms, word-of-mouth, and advertising, specifically, interactive innovation having critical mass in technology acceptance research. Thus, this study investigates imitation influence in individual adoption of mobile communication technology, more specifically, mobile phones, using Mahaian's diffusion model in individual ICT adoption.

• 한국안전학회지
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• 제19권3호
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• pp.89-94
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• 2004

Most reinforcements in concrete are constructed by steel. Corrosion of reinforcement is the main cause of damage and early failure of reinforced concrete structures. The corrosion is mainly professed by the chloride ingress. In general, chloride in concrete can be discriminated by two components, total chloride and fire chloride. This paper provides a testing method on the coefficient of chloride diffusion in concrete and the relationship between total chloride and free chloride in concrete for the composition of predicting model on diffusion rate of chloride. In order to complete this predicting model, this study will use chloride penetration characteristic, diffusion coefficient and experiment of color change on silver nitrate solution. This predicting model is going to help that grasp special quality on salt content inclusion of concrete structure that is exposed in chloride environment. Accurate predicting model can be effectively used not only in selecting of repair time but also in preventing from various deteriorations.

• 응용통계연구
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• 제31권6호
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• pp.801-810
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• 2018

확산은 금융이나 물리적 현상의 모형화에 이용되는 확률과정이다. 반복적으로 관측된 확산과정에 대하여 통계적인 모형을 구축할 때, 확률효과를 고려할 필요가 있다. 이 연구에서는 Ornstein-Uhlenbeck 확산모형과 geometric Brownian motion 확산모형에 대하여 확률효과를 도입한다. 모형모수에 대한 최도우도추정법을 적용하기 위하여, 확률효과에 대한 적절한 분포를 가정하여 닫힌 형태로 우도함수를 얻는 방법을 탐색하였다. 1991년부터 2017년까지 27년간 일일 단위로 기록된 다우존스 산업지수에 대하여 확률효과 모형을 적용하였다.