• Title/Summary/Keyword: diffusion theory

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ISRI - Information Systems Research Constructs and Indicators: A Web Tool for Information Systems Researchers

  • Varajao, Joao;Trigo, Antonio;Silva, Tiago
    • Journal of Information Science Theory and Practice
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    • v.9 no.1
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    • pp.54-67
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    • 2021
  • This paper presents the ISRI (Information Systems Research Indicators) Web tool, publicly and freely available at isri.sciencesphere.org. Targeting Information Systems (IS) researchers, it compiles and organizes IS adoption and use theories/models, constructs, and indicators (measuring variables) available in the scientific literature. Aiming to support the IS theory development process, the purpose of ISRI is to gather and systematize information on research indicators to help researchers and practitioners' work. The tool currently covers eleven theories/models: DeLone and McLean's IS Success Model (D&M ISS); Diffusion of Innovations Theory (DOI); Motivational Model (MM); Social Cognitive Theory (SCT); Task-Technology Fit (TTF); Technology Acceptance Model (TAM); Technology-Organization-Environment Framework (TOE); Theory of Planned Behavior (TPB); Decomposed Theory of Planned Behavior (DTPB); Theory of Reasoned Action (TRA); and Unified Theory of Acceptance and Use of Technology (UTAUT). It also includes currently over 400 constructs, nearly 2,500 indicators, and about 60 application contexts related to the models. For the creation of the tool's database, nearly 580 references were used.

Nonequilibrium Distribution Function Theory of Many-Particle Effects in the Reversible Reactions of the Type A+B ↔ C+B

  • Lee, Jin-Uk;Uhm, Je-Sik;Lee, Woo-Jin;Lee, Sang-Youb;Sung, Jae-Young
    • Bulletin of the Korean Chemical Society
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    • v.26 no.12
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    • pp.1986-1990
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    • 2005
  • We study the relaxation kinetics of reversible reactions of the type A + B $^\leftarrow_\rightarrow$ C + B by applying the manyparticle kernel theory, which we have developed to investigate many particle effects on general diffusioninfluenced reactions. It is shown that for the target model, where A and C molecules are immobile and their interconversion is induced by the encounter with the B molecules that are present in much excess, the manyparticle kernel theory gives a result that coincides with the known exact result.

EVELOPMENT OF AXISYMMETRIC MULTI-SPECIES GH EQUATION FOR HYPERSONIC RAREFIED FLOW ANALYSES (극초음속 희박유동 해석을 위한 축대칭 다화학종 GH 방정식의 개발)

  • Ahn, J.W.;Kim, C.
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.84-91
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    • 2008
  • Generalized hydrodynamic (GH) theory for multi-species gas and the computational models are developed for the numerical simulation of hypersonic rarefied gas flow on the basis of Eu's GH theory. The rotational non-equilibrium effect of diatomic molecules is taken into account by introducing excess normal stress associated with the bulk viscosity. The numerical model for the diatomic GH theory is developed and tested. Moreover, with the experience of developing the dia-tomic GH computational model, the GH theory is extended to a multi-species gas including 5 species; O$_2$, N$_2$, NO, O, N. The multi-species GH model includes diffusion relation due to the molecular collision and thermal phenomena. Two kinds of GH models are developed for an axisymmetric flow solver. By compar-ing the computed results of diatomic and multi-species GH theories with those of the Navier-Stokes equations and the DSMC results, the accuracy and physical consistency of the GH computational models are examined.

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EVELOPMENT OF AXISYMMETRIC MULTI-SPECIES GH EQUATION FOR HYPERSONIC RAREFIED FLOW ANALYSES (극초음속 희박유동 해석을 위한 축대칭 다화학종 GH 방정식의 개발)

  • Ahn, J.W.;Kim, C.
    • 한국전산유체공학회:학술대회논문집
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    • 2008.10a
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    • pp.84-91
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    • 2008
  • Generalized hydrodynamic (GH) theory for multi-species gas and the computational models are developed for the numerical simulation of hypersonic rarefied gas flow on the basis of Eu's GH theory. The rotational non-equilibrium effect of diatomic molecules is taken into account by introducing excess normal stress associated with the bulk viscosity. The numerical model for the diatomic GH theory is developed and tested. Moreover, with the experience of developing the dia-tomic GH computational model, the GH theory is extended to a multi-species gas including 5 species; $O_2,\;N_2$, NO, O, N. The multi-species GH model includes diffusion relation due to the molecular collision and thermal phenomena. Two kinds of GH models are developed for an axisymmetric flow solver. By compar-ing the computed results of diatomic and multi-species GH theories with those of the Navier-Stokes equations and the DSMC results, the accuracy and physical consistency of the GH computational models are examined.

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The Effect of Cognitive Absorption on the Individual Intention of Technology Acceptance: An Empirical Study on the MP3 Player (인지적 몰입이 개인의 기술 수용에 미치는 영향: MP3 플레이어에 대한 실증 연구)

  • Kim, Bo-Youn;Lee, Sang-Gun;Kang, Min-Cheol
    • Asia pacific journal of information systems
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    • v.16 no.1
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    • pp.45-69
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    • 2006
  • Technology Acceptance Model (TAM) has been widely used to predict user's behavior to accept the technology. Prior researches have been mainly focused on innovation constructs such as perceived usefulness and perceived ease of use. However, very little research has been conducted to understand individual mental beliefs in technology acceptance and imitation influence. This study integrates Technology Acceptance Model (TAM), Flow Theory (FT) and Diffusion of Innovation Theory (DIT). This paper indicates that imitation context, cognitive absorption (CA) based Flow theory and innovation context are the three important factors influencing user acceptance of information technologies. The proposed model has been tested among 232 users of MP3 players. Results showed that innovation context and cognitive absorption have positive influences on intention to use technology. Not all factors of the imitation context have direct effect on intention to use. However, we found that imitation context has positive influence on intention to use technology through cognitive absorption.

A Literature Study on PyoBon·GeunGyul Theory (표본(標本)·근결(根結) 이론과 임상응용에 관한 고찰(考察))

  • Jang, Jun-Hyouk;Kim, Kyung-Ho
    • Journal of Acupuncture Research
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    • v.17 no.1
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    • pp.175-187
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    • 2000
  • PyoBon GeunGyul - one of the twelve regular meridians theory - play a important role on the principle of point selection and point prescription in acumoxibustion. PyoBon explain the connection of the concentration and diffusion of channel qi, GeunGyul explain the relation of both poles of channels flow. So, Geun and Bon means the starting point of channel qi, and Pyo and Gyul means the terminal point of channel qi. But the flow of channel qi on PyoBon GeunGyul different from today's circulation courses of twelve regular channels based on Kyungmaek(經脈) chapter of Youngchu. Thus this study investigate the contents of PyoBon GeunGyul and consider its connection with channel flow. The results are as follows : 1. PyoBon GeunGyul theory explain that the relation of the limbs and trunk at meridian and emphasize that the connection of meridian and the importance of the limb acupoints. 2. PyoBon GeunGyul theory can be understandable in the view of the primordial qi and explain that the primordial qi of twelve regular channels acts from the limbs to the trunk. 3. PyoBon GeunGyul theory is based on the system of primordial qi channel which circulates from fingers and toes facing toward heart or the head, different from today's circulation courses of twelve regular meridians. 4. PyoBon GeunGyul theory act as a basis of principle of a part or distant point selection which applicated widely in acumoxibustion.

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A model for columnar-dendritic solidification of binary alloys accounting for dendrite tip undercooling (선단과냉을 고려한 이원합금의 주상 수지상응고 모델)

  • Yu, Ho-Seon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.5
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    • pp.698-707
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    • 1998
  • A simplified model for predicting microsegregation during columnar-dendritic solidification of binary alloys is developed, in which back diffusion, dendrite arm coarsening and dendrite tip undercooling are simultaneously incorporated. The inclusion of tip undercooling is accomplished by modifying the initial conditions of the existing solute diffusion model, in such forms that tip undercooling depresses the beginning of solidification below the liquidus temperature, and that the secondary arm spacing evolves in accordance with the minimum undercooling theory. Sample calculations for the well-known benchmark system show that the present predictions not only consist with the extablished limiting cases, but also agree favorably with the available experimental data within a reasonable tolerance. In particular, a typical decreasing trend in the eutectic fraction at high cooling rates is successfully resolved. Comparison of the individual and combined effects of characteristic parameters in reference with the limiting cases reveals the interactions among parameters. Every parameter plays the role of reducing the eutectic fraction, and the degree of influence depends primarily on the cooling rate. Coarsening enhances the effect of tip undercooling, while suppressing that of back diffusion. A vigorous back diffusion seems to restrain the apperance of the undercooling effect. Overall, each contribution of the three parameters to microsegregation is estimated to be of the same order, which suffices to justify the present study.

Measurement and Analysis of Diffusivity for SBS/cyclic Solvent Systems Using CCIGC Technique (CCIGC 기법을 사용한 SBS/cyclic solvent 시스템에서의 확산계수 측정 및 해석)

  • Kim, Jiui;Hong, Seong Uk
    • Applied Chemistry for Engineering
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    • v.25 no.2
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    • pp.147-151
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    • 2014
  • In many polymer processing operations, the diffusion of small molecules in polymeric materials plays an important role. The fundamental physical property required to design and optimize processing operations is the mutual diffusion coefficient. To investigate the transport properties of polymer/solvent systems at infinite dilution, capillary column inverse gas chromatography (CCIGC) is often employed. In this study, diffusion and partition coefficients of cyclic solvents in styrene/butadiene/styrene (SBS) block copolymer were measured over a wide temperature range using the CCIGC technique.

A Study on the Soot Particle Measurement in Co-Flow Diffusion Flame Using a Laser Diagnostics and a Thermocouple (레이저 및 열전대를 이용한 동축류 확산화염에서의 매연입자 측정에 관한 연구)

  • Han, Yong-Taek;Lee, Ki-Hyng;Lee, Won-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.7
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    • pp.863-870
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    • 2004
  • The temperature and soot particle measurement technique in a laminar diffusion flame has been studied to investigate the characteristics of soot particle with temperature using a co-flow burner. The temperature distribution in the flame were measured by rapid insertion of a R-type thermocouple and the soot particles by LEM/LIS techniques. In these measurement, soot volume fraction, number density and soot diameters were analyzed experimentally. As a results, the spacial distributions of particle volume fraction, soot diameter, and number density are mapped throughout the flame using the Rayleigh theory for the scattering of light by particles. A laser extinction method was used to measure the soot volume fraction and laser induced scattering method was used to measure the soot particle diameter and number density. Also, we measured temperature without the effect of soot particles attached to the thermocouple junction, which is close to the nozzle. In this result, we found that upstream zone has a unstable flowing in co-flow diffusion flame and the y-axis temperature of flame has a uniform temperature distribution in the most soot volume fraction zone.

A Study on the Soot Particle Measurement in Co-flow Diffusion Flame Using a Laser Diagnostics and a Thermocouple (레이저 및 열전대를 이용한 동축류 확산화염에서의 매연입자 측정에 관한 연구)

  • Han, Yong-Taek;Lee, Ki-Hyung;Lee, Won-Nam
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1267-1273
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    • 2004
  • The temperature and soot particle measurement technique in a laminar diffusion flame have been studied to investigate the characteristics of soot particle with temperature using a co-flow burner. The temperature distributions in the flame were measured by rapid insertion of a R-type thermocouple and the soot particles were detected were detected by LEM/LIS techniques. In these measurement, soot volume fraction, number density and soot diameters were analyzed experimentally. As a results, the spacial distributions of particle volume fraction, soot diameter, and number density are mapped throughout the flame using the Rayleigh theory for the scattering of light by absorbing particles. A laser extinction method was used to measure the soot volume fraction and Laser induced scattering method was used to measure the soot particle diameter and number density. Also, we measured temperature without the effect of soot particles attached to the thermocouple junction, which is close to the nozzle. In this result, we found that upstream zone has a unstable flowing in co-flow diffusion flame and the y-axis temperature of flame has a uniform temperature distribution in the most soot volume fraction zone.

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