• 한국경영과학회지
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• 제31권2호
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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.

• 대한원격탐사학회지
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• 제19권6호
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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.

• 대한수학회지
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• 제57권1호
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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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• 제13권1호
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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.

• 한국해안해양공학회지
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• 제8권2호
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• pp.204-214
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• 1996

본 연구의 목적은 새만금해역에서 방조제 축조에 따른 토사의 이동형태변화와 토사 확산을 알아보는 데 있다. 유동은 조석잔차류와 관측된 바람, 수온, 염분자료를 이용하여 계산되었다. 유동에 의한 토입자의 3차원적 거동은 Euler-Lagrange 방법으로 추적하였다. 방조제 축조에 따른 토사확산 및 이동 형태는 금강 하구 남쪽에서 고군산군도 북쪽에 대부분의 토사를 퇴적시켰다. 이것은 잔차류의 영향으로 판단된다.

• 가정과삶의질연구
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• 제27권3호
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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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• 제29권2호
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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.

• 한국경제지리학회지
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• 제18권2호
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• pp.224-241
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• 2015

본 연구의 목적은 문화콘텐츠 상품의 소비 및 확산에 나타나는 시공간적 특징을 밝히는 것이다. 이를 위하여 본 연구에서는 최근 전 세계적 인기를 누리며 확산되고 있는 싸이의 "강남스타일" 뮤직비디오의 확산과정을 분석한다. 특히 싸이의 "강남스타일"이 유튜브에 탑재된 이후 4~6개월간의 지역별 유튜브 조회 수와 트윗 자료 및 구글 검색 수를 바탕으로 이들이 확산되어 나가는 과정의 시공간적 특성을 파악 한다. 분석 결과 뮤직비디오와 같은 문화콘텐츠 상품의 경우 물리적인 공간 거리와 무관할 수 있는 온라인 매체를 통한 확산의 경우도 지역에 따라 전파되는 시점과 전개 과정이 상이함을 확인하였다. 특히 언어, 문화적 연관성 및 한류에 대한 호의성 및 배타성 등으로 정의될 수 있는 문화적 거리가 이러한 문화 상품의 확산에 영향을 미치는 것으로 판단된다.

• 인터넷정보학회논문지
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• 제7권2호
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• pp.93-102
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• 2006

상호작용적 성격을 갖는 통신서비스의 수요확산패턴은 네트워크 효과에 기인한 임계 가입자 규모에 상당한 의존을 보이고 있으며, 이로 인한 통신서비스의 지연 확산 시기 현상이 발생하고 있다. 그러나 통신망이 회선교환망에서 패킷교환망으로 빠르게 진화하고 또한 다양한 패킷기반 서비스들이 개발, 제공됨에 따라 이러한 통신서비스의 확산 패턴 상의 특성은 변화하고 있다. 내구재를 대상으로 수요 확산 패턴을 분석한 기존 연구들과 국내 6개 회선기반서비스 그리고 역시 6개 패킷기반서비스의 확산 패턴을 비교 분석한 결과, 기존 회선기반서비스들에서 보인 지연 확산 시기 현상은 존재하지 않았으며. 뿐만 아니라 다른 내구재들의 초기 확산보다 더 빠른 확산 속도를 보임으로서 오히려 빠른 확산 시기 현상이 발생하고 있음을 발견하였다. 이러한 결과를 바탕으로 향후 신규 통신서비스 확산 전략은 기존의 통신서비스 보급 및 확산을 위한 초기 단계에서의 촉진전략에서 성장 단계의 확산 유지 및 확대 전략이 보다 유용한 전략임을 제시하였다.

• 한국전산유체공학회지
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• 제19권1호
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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.