• Kyungpook Mathematical Journal
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• 제49권2호
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• pp.299-312
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• 2009

In the present paper we investigate the existence of almost periodic processes of ecological systems which are presented with nonautonomous N-dimensional impulsive Lotka Volterra competitive systems with dispersions and fixed moments of impulsive perturbations. By using the techniques of piecewise continuous Lyapunov's functions new sufficient conditions for the global exponential stability of the unique almost periodic solutions of these systems are given.

• 한국정보시스템학회지:정보시스템연구
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• 제25권4호
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• pp.63-85
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• 2016

Purpose While the popularity of C2C auction platforms such as eBay is gradually decreased, this domain is still undermined to explain online bidding behaviors. Online bidders sometimes engage in impulsive bidding due to some of the online auction characteristics. Therefore, this study develops and tests a model of the impulsive bidding exhibited by online bidders in C2C auction platforms. Based on S-O-R framework, our model posits that both perceived time-pressure and competition intensity affect cognitive absorption which ultimately influences the impulsive bidding. Design/methodology/approach This study collected survey data from 214 C2C auction participants, who have prior experience on impulsive bidding and tested both measurement model and structural model by using CB-SEM (covariate-based structural equation modelling) technique. In this study, by using AMOS 20.0, we tested the measurement model for its overall fit, item reliability, and validity and further conducted the structural model to test our proposed hypotheses. Findings Based on our results, we found that perceived tim-pressure and competition intensity were positively related to cognitive absorption. We also found that the cognitive absorption was positively associated with impulsive bidding behavior. In this study, by developing our research model in S-O-R framework, we provide an alternative theoretical mechanism to describe online impulsive bidding behavior.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제14권4호
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• pp.225-247
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• 2010

In this paper, we establish a two-competitive-prey and one-predator Holling type II system by introducing a proportional periodic impulsive harvesting for all species and a constant periodic releasing, or immigrating, for the predator at different fixed time. We show the boundedness of the system and find conditions for the local and global stabilities of two-prey-free periodic solutions by using Floquet theory for the impulsive differential equation, small amplitude perturbation skills and comparison techniques. Also, we prove that the system is permanent under some conditions and give sufficient conditions under which one of the two preys is extinct and the remaining two species are permanent. In addition, we take account of the system with seasonality as a periodic forcing term in the intrinsic growth rate of prey population and then find conditions for the stability of the two-prey-free periodic solutions and for the permanence of this system. We discuss the complex dynamical aspects of these systems via bifurcation diagrams.

• 한국항행학회논문지
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• 제24권6호
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• pp.587-592
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• 2020

사물 인터넷 패러다임에 의해 가능해진 거대한 정보 교환은 즉시 사용 가능한 인프라로 전선을 이용할 가능성이 높아지고 있다. 사전에 설치된 배선 네트워크 인프라를 사용하는 이점은 전력선 통신을 광대역 통신을 위한 경쟁력있는 기술로 만들었다. 따라서 기존의 전력선 통신 채널을 고속 데이터 전송 및 인터넷 서비스를 위한 효과적인 수단으로 사용하는 것에 대한 관심이 높아지고 있다. 전력선 통신 시스템에 영향을 미치는 주요 잡음의 유형 중 하나는 임펄스 잡음이며 본 논문은 임펄스 잡음이 OFDM-QPSK 시스템의 성능에 미치는 영향을 해석하였다. 임펄스 잡음의 성능 분석을 위하여 3가지 환경에서 측정된 데이터를 사용하였다. 분석을 통해 OFDM-QPSK 시스템이 대부분의 임펄스 잡음 사례에서 QPSK 시스템보다 우수한 것으로 나타났다. 또한 RS 부호화된 OFDM-QPSK 시스템은 3 가지 경우의 임펄스 잡음 환경에서 우수한 BER 성능을 달성할 수 있었다.