• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.2
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• pp.15-26
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• 2006

In reality, we can observe anomalous diffusion patterns of cycle-recycle or rejuvenation. Abrupt changes in the market environment such as sudden currency devaluation or change in government policy or those in marketing strategies such as drastic repositioning can lead to such atypical diffusion patterns. The authors present extended Bass models that incorporate effects of such abrupt changes of external factors into the hazard rate and the market potential. Using a set of compact-car data affected by a drastic change in the government policy, they illustrate the strengths of the proposed models.

• Korean Journal of Remote Sensing
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• v.19 no.6
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• pp.479-490
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• 2003

This study proposed a modified anisotropic diffusion restoration for image classification. The anisotropic diffusion restoration uses a probabilistic model based on Markov random field, which represents geographical connectedness existing in many remotely sensed images, and restores them through an iterative diffusion processing. In every iteration, the bonding-strength coefficient associated with the spatial connectedness is adaptively estimated as a function of brightness gradient. The gradient function involves a constant called "temperature", which determines the amount of discontinuity and is continuously decreased in the iterations. In this study, the proposed method has been extensively evaluated using simulated images that were generated from various patterns. These patterns represent the types of natural and artificial land-use. The simulated images were restored by the modified anisotropic diffusion technique, and then classified by a multistage hierarchical clustering classification. The classification results were compared to them of the non-restored simulation images. The restoration with an appropriate temperature considerably reduces error in classification, especially for noisy images. This study made experiments on the satellite images remotely sensed on the Korean peninsula. The experimental results show that the proposed approach is also very effective on image classification in remote sensing.

• Journal of the Korean Mathematical Society
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• v.57 no.1
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• pp.249-281
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• 2020

A reaction-diffusion model with spatiotemporal delay modeling the dynamical behavior of a single species is investigated. The parameter regions for the local stability, global stability and instability of the unique positive constant steady state solution are derived. The conditions of the occurrence of Turing (diffusion-driven) instability are obtained. The existence of time-periodic solutions, the existence and nonexistence of nonconstant positive steady state solutions are proved by bifurcation method and energy method. Numerical simulations are presented to verify and illustrate the theoretical results.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.1
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• pp.21-29
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• 2009

This paper treats the conditions for the existence and stability properties of stationary solutions of a predator-prey interaction with self and cross-diffusion. We show that at a certain critical value a diffusion driven instability occurs, i.e. the stationary solution stays stable with respect to the kinetic system (the system without diffusion) but becomes unstable with respect to the system with diffusion and that Turing instability takes place. We note that the cross-diffusion increase or decrease a Turing space (the space which the emergence of spatial patterns is holding) compared to the Turing space with self-diffusion, i.e. the cross-diffusion response is an important factor that should not be ignored when pattern emerges.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.204-214
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• 1996

The purpose of this study is to find a variation in traveling patterns of soil and soil diffusion due to construction of the sea dike in Saemangum coastal sea region. Water circulations are calculated diagnostically from the observed water temperature, salinity and wind data, and tidal residual current. Three-dimensional movements of injected particles due to currents, turbulence and sinking velocity are tracked by the Euler-Lagrangian method. Calculated a variation in traveling patterns of soil and soil diffusion due to construction of the sea dike deposited mostly from estuarine area of the Geum River to Gokunsan coastal sea region. This results are believed to be the combined effect of coastal circulation.

• Journal of Families and Better Life
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• v.27 no.3
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• pp.201-212
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• 2009

The purpose of research is to investigate patterns and diffusion of consumer participation on Internet UCC based on digital contents services. A sample survey of internet users was conducted, responses were collected from 629 respondents and consumer streaming data were analyzed. Some of the practical implications of the results are follows. Research can find out that patterns of user participation in UCC. The major genres of UCC are like daily lives of individuals, humors, parodies of star entertainers and types of contents like still pictures or images, texts are relatively highly generated comparing with multimedia UCC. Although participants have been being increased in UCC recently, the consumers as prosumers who are classified in contents generating group are ten percents at the most. In generating community-based UCC such as posting answers of questions and activities in Blog, prosumers who are in contents making group(recreational group) show more positive attitudes than simple participants(consuming only). The results of multiple regression analysis indicated that fun & entertainment, arousal, self-expression, user friendly web interface variable commonly posited a significant effect in multimedia UCC Services between two groups. Information sharing and perceived usefulness posited a significant effect in recreational group.

• Asia pacific journal of information systems
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• v.29 no.2
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• pp.217-247
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• 2019

This paper draws on the interdependence theory to examine the role of power and mutual dependence on the relationship between internal/external diffusion and performance improvement within a supply chain. The results from a survey of 375 respondents show that two patterns of IOS diffusion - internal diffusion and external diffusion - have different impacts on a firm's performance improvement according to differences in power and mutual dependence between two parties in the supply chain.

• Journal of the Economic Geographical Society of Korea
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• v.18 no.2
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• pp.224-241
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• 2015

This study investigates the time-space characteristics of the consumptions of cultural-contents commodities and their spatial diffusion progresses via digital media. For the purpose, we examine the spatial diffusion patterns of PSY's Music Video "Gangnam Style" since it has been launched on the YouTube. By visualizing the spacio-temporal progresses of YouTube, Tweet, and Google searching data during four months after launching, we examine the time-space characteristics of diffusion patterns of the music video via each media. We found that the adapting time and the diffusion progress were not in accordance at each country. The results revel that cultural distance such as characterized by language, cultural linkage, exclusivism or courtesy for the 'Hanrue' affects quite strongly on the spatial diffusion of music video rather than physical distance.

• Journal of Internet Computing and Services
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• v.7 no.2
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• pp.93-102
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• 2006

Traditionally, diffusion of telecommunications services has been considerably affected by presence of critical mass and network externalities, and thus shown the so-called late take-off phenomenon. However, as telecommunications network evolves from circuit switching to packet switching, enabling diverse new services such as Internet access, Internet banking and web hosting, it seems this traditional diffusion patterns are changing. By comparing diffusion of the packet-based services with those of circuit-based services and durable goods, we have found the late take-off phenomenon is not involved in diffusion of newly introduced the packet-based services. Moreover, we concluded diffusion of the packet-based services is much faster than that of durable goods, thus showing early take-off phenomenon. Based on this empirical result, we suggest Telcos and ISPs should pay as much attention to the growth state as the introduction stage in order for their packet-based services to be successful in the markets.

• Journal of computational fluids engineering
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• v.19 no.1
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• pp.15-20
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• 2014

Accurate simulation of free-surface wave flows around a ship is very important for better hull-form design. In this paper, a computational fluid dynamics (CFD) code, termed SNUFOAM, which is based on the open source libraries, OpenFOAM, was developed to predict the wave patterns around a ship. Additional anti-diffusion source term for minimizing a numerical diffusion, which was caused by convection differencing scheme, was considered in the volume-fraction transport equation. The influence of the anti-diffusion source term was tested by applying it to free-surface wave flow around the Wigley model ship. In results, the band width of the volume fraction contours between 0.1 to 0.9 at the hull surface was narrowed by considering the anti-diffusion term.