• Title/Summary/Keyword: Diffusion Theory

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Challenges of Diffusion of Innovation Theory on Agricultural Extension and Its Implications (농촌지도사업에서 혁신전파이론의 이론적 함의)

  • Park, Duk-Byeong;Lee, Min-Soo
    • Journal of Agricultural Extension & Community Development
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    • v.13 no.1
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    • pp.1-14
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    • 2006
  • The diffusion of innovation theory provided the basis for a model of agricultural development that the extension service continues to use today. This study aims to examine the history, influence, and impacts of innovation diffusion theory on the extension service. It reviews some of the major developments in the literature related to the theory, examines its criticisms, and discusses the implications for extension. As such, innovators are younger, more cosmopolitan, have higher incomes than later adopters, and have the largest operations of all adopter categories. There are two critiques on diffusion of innovation theory in which are the method and inequity recurring from diffusion.

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A new approach for calculation of the neutron noise of power reactor based on Telegrapher's theory: Theoretical and comparison study between Telegrapher's and diffusion noise

  • Bahrami, Mona;Vosoughi, Naser
    • Nuclear Engineering and Technology
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    • v.52 no.4
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    • pp.681-688
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    • 2020
  • The telegrapher's theory was used to develop a new formulation for the neutron noise equation. Telegrapher's equation is supposed to demonstrate a more realistic approximation for neutron transport phenomena, especially in comparison to the diffusion theory. The physics behind such equation implies that the signal propagation speed is finite, instead of the infinite as in the case of ordinary diffusion. This paper presents the theory and results of the development of a new method for calculation of the neutron noise using the telegrapher's equation as its basis. In order to investigate the differences and strengths of the new method against the diffusion based neutron noise, a comparison was done between the behaviors of two methods. The neutron noise based on SN transport considered as a precision measuring point. The Green's function technique was used to calculate the neutron noise based on telegrapher's and diffusion methods as well as the transport. The amplitude and phase of Green's function associated with the properties of the medium and frequency of the noise source were obtained and their behavior was compared to the results of the transport. It was observed, the differences in some cases might be considerable. The effective speed of propagation for the noise perturbations were evaluated accordingly, resulting in considerable deviations in some cases.

The Effect of Social Networks on the Diffusion of Innovation (사회네트워크가 혁신확산에 미치는 영향)

  • 이규현;오장균
    • Journal of Korea Technology Innovation Society
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    • v.3 no.2
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    • pp.33-47
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    • 2000
  • We focus on the investigations of the effect of social networks on the diffusion of innovations, in order to successfully bring innovations into markets. We begin with consideration of social system from Rogers(1995)' perspective, which includes the fifty-year sequential tradition of diffusion studies, and expand the conceptualization into a framework for thinking about the effect of social networks on the diffusion of innovations. We draw upon basic ideas from the research traditions of social network theory in sociology, and social identity theory in social psychology. Finally, we offer propositions for the future empirical researches. A better understanding of social networks can complement research on the diffusion of innovations and help in the development of a universal model of consumer response to innovations.

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Comparison of the Bass Model and the Logistic Model from the Point of the Diffusion Theory (확산이론 관점에서 로지스틱 모형과 Bass 모형의 비교)

  • Hong, Jung-Sik;Koo, Hoon-Young
    • Journal of the Korean Operations Research and Management Science Society
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    • v.37 no.2
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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.

An Empirical Study on the EDI Diffusion and Performance (EDI 시스템의 확산과 성과에 관한 실증적 연구)

  • Lee, Jae-Won;Lee, Young-Hwan
    • Asia pacific journal of information systems
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    • v.10 no.4
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    • pp.1-20
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    • 2000
  • Electronic Data Interchange(EDI) has the potential to improve business operations by expediting the exchange of business documents. It will also provide substantive operational and strategic benefits to the trading firms. However, the successful implementation of EDI systems requires the mutual trust and cooperation between the trading firms. The extent of EDI diffusion and performance depends on inter-organizational, intra-organizational, as well as innovation factors. Researches based on the sociopolitical process framework in the use of IT, organizational theory, resource dependence theory, and innovation diffusion theory have identified 3 inter-organizational variables(transaction climate, dependence, external IS expert support) and 4 intra-organizational variables(strategic IS planning, infrastructure, top management support, education/training,), and 3 innovation variables(compatibility, relative advantage, cost) that affect EDI diffusion. In this study, a multi-dimensional measure on EDI diffusion has been developed to capture the external and internal integration. Then, the influence of these 10 variables on the extent to which the EDI adopting firms pursue diffusion has been examined. Whether more diffusion leads to superior performance has also been studied. International trade managers from 107 firms in the trade industry participated in a field survey. The results based on a structural equation model(SEM), developed using AMOS, provide quite a strong support for the hypothesized relations. Both education/training and IT infrastructure influenced external and internal diffusion of EDI systems. Internal diffusion of EDI enables the adopting firms to improve operational and strategic performance, whereas external diffusion contributes only to operational performance.

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Diffusion Coefficients of Polyimide/N-Methyl-2-Pyrrolidone Systems below Glass Transition Temperature (유리전이온도이하에서의 Polyimide/N-Methyl-2-Pyrrolidone계의 확산계수)

  • 박광승;김덕준
    • Polymer(Korea)
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    • v.24 no.2
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    • pp.194-200
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    • 2000
  • The diffusion coefficients in polyimide/N-methyl-2-pyrrolidone (NMP) systems were proposed using tile Vrentas-Duda's hole free volume theory. Several free volume parameters included in the diffusion coefficients were obtained from the fundamental physical properties of polyimide and NMP and group contribution theory, and the pre-exponential diffusion coefficient, D$_{0}$ was also determined from the dynamic swelling behavior of polyimide in NMP solution. The experimental swelling behavior of polyimide films in NMP was well described by the theoretical one using the proposed diffusion coefficient.t.

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Prediction of PolymerSolvent Diffusion Coefficients Using Free-Volume Theory (자유부피이론을 이용한 고분자/용매 확산계수의 예측)

  • 홍성욱
    • Proceedings of the Membrane Society of Korea Conference
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    • 1997.10a
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    • pp.27-30
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    • 1997
  • 1. Introduction : Molecular diffusion of small molecules in polymers plays an important role in many areas where polymers are acting as barriers, and in separation processes, such as selective diffusion. Different applications of polymers have different requirements on their transport properties. Therefore, reliable predictions of diffusion coefficients for small molecules in polymeric materials could be a useful tool to design appropriate materials. For many years, the theories based on free-volume concepts have been widely used to correlate and predict diffusion behavior in polymer/solvent systems. In the theory derived by Vrentas and Duda, the empty space between molecules that is available for molecular transport, referred to as hole free-volume, is being redistributed. Molecular transport will occur only when a free-volume of sufficient size appears adjacent to a molecule and the molecule has enough energy to jump into this void. The diffusive jump is considered complete when the void left behind is closed before the molecule returns to its original position. In this paper, the Vrentas-Duda free-volume theory is presented and the methods to estimate free-volume parameters for predicting polymer/ solvent diffusion coefficients are described in detail.

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Diffusion Theory of Spin Injection (스핀 주입에 대한 퍼짐 이론)

  • Lee, B.C.
    • Journal of the Korean Magnetics Society
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    • v.16 no.2
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    • pp.121-129
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    • 2006
  • The diffusion theory for spin injection from magnetic layer into nonmagnetic layer was reviewed. Basic equations were derived and applied to a ferromagnet/semiconductor/ferromagnet system. The spin polarization and magnetoresistance were calculated. The reason for difficulty in detecting spin injection with magnetoresistance was explained, and a possible solution was discussed.

Oxygen diffusion on W(110) : Comparison of experiment and theory (W(110)면에서의 산소의 확산 : 실험과 이론의 비교)

  • 남창우;홍진표;김채옥
    • 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.

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Modeling of ion diffusion coefficient in saturated concrete

  • Zuo, Xiao-Bao;Sun, Wei;Yu, Cheng;Wan, Xu-Rong
    • Computers and Concrete
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    • v.7 no.5
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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.