• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.736-742
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• 2003

This paper presents the propagation path loss in a tunnel which is a kinds of underground environments. To predict propagation path loss more accurately, we choose a straight tunnel with rectangular cross-section. The simulated receiver powers that are using a hybrid waveguide model and a Ray-Tracing method, are compared with the measured ones as a function of distance between TX and RX antennas in tunnel. The attenuation value of regression analysis for measured power in the tunnel is 0.0238dB/m which is similar to the one of the EH1.2 mode, 0.0246dB/m in hybrid waveguide model. By comparing simulation with measurement in tunnels, it has been shown that the measured values are approximate to the simulated results of ray-tracing model. In the analysis of wide-band channel characteristics of the tunnel, the more the distance between TX and RX antennas in tunnel increases, RMS delay spread increases and coherence bandwidth decreases.

• The Journal of the Korea Contents Association
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• v.14 no.1
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• pp.165-178
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• 2014

Recently, the social network game (SNG) industry is expanding at a fast pace by the increase in the charged item sales. The objective of the present study is to explore factors influencing user intention to purchase charged items. Based on the literature review, flow has been introduced as an influential factor of the intention to purchase and individual influence, social relationship, and social influence as factors of flow. Enjoyment and self-competence are assumed to be measurement constructs for individual influence, social interaction and self-presentation for social relationship, social norm and perceived critical mass for social influence. Empirical analysis show that enjoyment and self-presentation has significant influence on users' flow while self-competence and social interaction has not. Also social norms and perceived critical mass directly influence intention to purchase items. Theoretical and practical implications are discussed by this results.

• The Journal of Bigdata
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• v.2 no.2
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• pp.47-56
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• 2017

The UTAUT was presented as a comprehensive of eight existing theories to improve the limit of Technology Acceptance Model (TAM), and it has been also utilizing in various fields related to acceptance and diffusion of new technology. In this study, we analyzed factors utilized in UTAUT through meta-analysis, and confirms the consistency of the model. We presented the principal factors and the additional factors. Moreover, we presented differences and suggestions through comparative analysis with previous researches. The meta-analysis showed that satisfaction, hedonic motivation, attitude, perceived enjoyment showed a important factors as additional factors. Based on this result, we presented an extended UTAUT model. In the case of Korea studies, it was found that increasing the degree of behavior intention is the most important factor leading to use behavior. The results of this research will be able to support researchers who research the acceptance and diffusion of new technologies, and companies trying to launch new products.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.1
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• pp.90-99
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• 1999

In this work, we consider the effect of the presheath on the ion angular distribution. The recent shows the ion-neutral collision in the presheath and the calculated energy flux with the ion angular distribution at the presheath edge in plasma reactor. We also propose a new approximation analytical model for the ion angular distribution and the energy flux distribution with ion temperature. The ion passing the presheath region, Shows a ion scattering effect without ion-neutral collisions. This because the kinetic energy by the ambipolar diffusion field is changed by the gas collision,. Using the proposed approximation analytical model, we show the simulated results of a deposit profile on variable trench shape.

• Information Systems Review
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• v.6 no.1
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• pp.19-36
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• 2004

The importance of Internet banking has been emphasized due to the spread of Internet and the potential advantages of Internet banking. In case of Korea, Internet banking users have been risen dramatically since 1999 after its introduction. The purpose of this study is to draw the antecedent variables that affect the adoption of Internet banking and show their effects empirically. In this paper, influencing factors are proposed to distinguishing Internet banking users from non-users. And nine hypotheses are empirically tested using logistic regression. The results show that most of hypotheses are supported except for complexity and IT innovativeness. And compatibility was found to have a strong positive effect on the adoption of Internet banking. Implications of these findings are discussed for researchers and practitioners.

• Polymer(Korea)
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• v.24 no.1
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• pp.105-112
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• 2000

Using a commercial epoxy/carbon fiber composite prepreg (DMS 2224) as a model system, the cure kinetics of vitrifying thermoset system were analyzed by isothermal and dynamic-heating experiments. Focusing on the processing condition of high performance composite systems, a phenomenological kinetic model was developed by using differential scanning calorimetry (DSC) and reaction kinetics theories. The model system exhibited a limited degree of cure as a function of isothermal temperature seemingly due to the diffusion-controlled reaction rates. The diffusion-controlled cure reaction was incorporated in the development of the kinetic model, and the model parameters were determined from isothermal experiments. The first order reaction was confirmed from the characteristic shape of isothermal cure thermograms, and the activation energy wes 78.43 kJ/mol. Finally, the proposed model was used to predict a complex autoclave thermal condition, which was composed of several isothermal and dynamic-heating stages.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.1
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• pp.73-79
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• 1983

Activated carbon has been widely used in water and wastewater treatment for removal of trace organics. The objective of this study was to define adsorption characteristics of trihalomethane(THM) on granular activated carbon(GAC) surfaces by laboratory experiments. Synthetic samples were prepared by adding chloroform into distilled and deionized water. The experiments conducted were a batch run and isotherm studies with five different temperature-pH levels. Adsorption of THM on GAC at an equilibrium condition was well described by the Freundlich isotherm equation. Lower temperature favored the adsorption, but the effect of pH was negligible. Utilizing the results of a batch run and the isotherm results, three parameters, mass transfer coefficient, pore diffusion coefficient, and surface diffusion coefficient, were evaluated by comparing with simulation results of an adsorption model. The results also showed that the pore diffusion was much greater than the surface diffusion.

• Archives of design research
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• v.13 no.1
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• pp.157-166
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• 2000

Since the cognitive science developed as a brandl of academic researdl, studies on human brains have flourished. Emotional features have been centered on the field of design, and the development of the design process has been diversified that makes use of the factors. The purpose of this study is to reflect the current trend and to convert the results into a method for designing. The researdl is based on the mind map techniques which spread like a trendy fashion, and tries to supply a theoretical explanation of how to overcome the fixed idea. Recognizing the importance of learned information in approaching a problem, I regarded the roles of left and right brain as analogue and digital images interpreting them by freely crossing language(digital images) and visual thought (analogue images), using mapping tedlniques. I pursued the research goal of the techniques focusing on the idea of using mapping. As a result of this. I established a logic system [figure 8] in that a proposition which starts as a problem introduction goes on until a problem solution, which is visualized with concept presentation, using a brainstorming technique. According to the suggested concept. I concluded that idea proliferation as a design demand can be solved by applying mapping techniques like one shown in figure 12.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.4
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• pp.165-173
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• 1998

Analytical solutions to predict the movement rate of submerged mound are derived using the convection coefficient and the joint distribution function of wave heights and periods. Assuming that the sediment is moved onshore due to the velocity asymmetry of Stokes' second order nonlinear wave theory, the micro-scale bedload transport equation is applied to the sediment conservation. The nonlinear convection-diffusion equation can then be obtained which governs the migration of submerged mound. The movement rate decreases exponentially with increasing the water depth, but the movement rate tends to increase as the spectral width parameter, $ u$ increases. In comparison of the analytical solution with the measured data, it is found that the analytical solution overestimates the movement rate. However, the agreement between the analytical solution and the measured data is encouraging since this over-estimation may be due to the inaccuracy of input data and the limitation of sediment transport model. In particular, the movement rates with respect to the water depth predicted by the analytical solution are in very good agreement with the estimated result using the discritization technique with the hindcast wave data.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.119-133
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• 2015

The paper reports on exploratory research into the factors influencing adoption of low impact development (LID) regulations by local government. The research uses ten case studies ranging from low to high level adoption of LID in Virginia. Based on the theory of diffusion of innovations, perceived characteristics of LID, characteristics of the adopting local government, motivations of the adopter, and the surrounding organizational context of the adopter are chosen for the key factors influencing on LID adoption. By reviewing the local governments regulations related to stormwater management, meeting minutes, reports and documents, and in-depth interviews, the evaluation of the key factors and the local LID adoption was conducted. As a result, adopters with a high level of LID adoption at the time of the study were heavily influenced by champions of LID within local government and communities. In contrast, moderate level adopters and low-level adopters emphasized the importance of external forces like state regulatory mandates and the need for clear models to implement.