• International Commerce and Information Review
• /
• v.16 no.4
• /
• pp.263-280
• /
• 2014

The dynamics of global alliance networks can be analyzed in numerous ways. We have chosen to approach it in terms of alliance stability. Although increasing academic attention has been devoted to the alliance dynamics field, the majority of prior research has neither contributed to a coherent knowledge foundation(an academic gap) nor provided adequate answers to managerial questions(a managerial relevance gap). We respond to their call for research by developing an integrated process model that integrates various studies on alliance stability. The primary tasks were (1) to characterize and conceptualize the stability concept to fill the academic gap, and (2) to identify critical endogenous factors underlying alliance stability over the different developmental stages to fill the managerial gap. Knowledge acquired in this paper is also expected to offer alliance managers and practitioners some valuable implications as they strive for stable and successful collaborative relationships. As one of the basic arguments, stability has been viewed as a necessary condition for the achievement of collaborative objectives. When firms form, implement, adjust and evaluate their alliances, they should have the goal of stability in mind. At the same time, management should be in a position to determine the specific actions needed for stability at any given moment in the alliance's lifetime.

• Journal of applied mathematics & informatics
• /
• v.26 no.1_2
• /
• pp.275-282
• /
• 2008

Our aim in this paper is to investigate the global attractivity of the recursive sequence $x_{n+1}$ = $\frac{\alpha-{\beta}x_{n-1}}{\gamma+g(x_n)}$ under specified conditions. We show that the positive (or zero for $\alpha$ = 0) equilibrium point of the equation is a global attractor with a basin that depends on certain conditions posed on the coefficients and the function g(x).

• Journal of applied mathematics & informatics
• /
• v.32 no.5_6
• /
• pp.843-848
• /
• 2014

In this paper, we investigate the boundedness character, the periodic character and the global behavior of positive solutions of the difference equation $$x_{n+1}=p_n+\frac{x_n}{x_{n-1}},\;n=0,1,{\cdots}$$ where $\{p_n\}$ is a two periodic sequence of nonnegative real numbers and the initial conditions $x_{-1}$, $x_0$ are arbitrary positive real numbers.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.8 no.1
• /
• pp.93-102
• /
• 2004

A model of three trophic level food chain with ratio dependence is considered. The existencem uniqueness and stability of its solutions are investigated.

• Journal of the Korean Mathematical Society
• /
• v.37 no.4
• /
• pp.593-611
• /
• 2000

For linear time-varying control systems with constrained control described by both differential and discrete-time equations in Banach spaces was give necessary and sufficient conditions for exact global null-controllability. We then show that for such systems, complete stabilizability implies exact null-controllability.

• Journal of the Korean earth science society
• /
• v.32 no.5
• /
• pp.461-473
• /
• 2011

In this paper, trends of the widely used stability indices (SIs) and environmental parameters (EPs) were examined by using the 30-year routine rawinsonde data observed in three upper air observatories (Osan, Gwangju and Pohang) over South Korea. To take into account of the contribution of water vapor to a parcel density, we applied the virtual temperature correction in calculating the SIs and EPs. The trends of SIs and EPs indicated significant increases of temperature and moisture contents, especially at the low-to-mid troposphere during the last 10 years. The warming trend in the lower troposphere shows about 3 times greater than that of the global average (+0.10- $+0.20^{\circ}C$/10 years), whereas the cooling trend of lower stratosphere demonstrates a similar trend with the global average (-0.33- $-0.60^{\circ}C$/10 years). The vertical stability is clearly reduced due to the unsymmetrical change of atmospheric elements. The unstabilizing trend with the increased moisture contents gradually changed the atmospheric environment in South Korea into the conditions favorable for the occurrence of severe weather or intensifications of such events. These trends are consistent with the recent observations, which showed clear increase in the intensity and frequency of heavy rainfalls.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.22 no.1
• /
• pp.29-62
• /
• 2018

We investigate a class of HIV infection models with two kinds of target cells: $CD4^+$ T cells and macrophages. We incorporate three distributed time delays into the models. Moreover, we consider the effect of humoral immunity on the dynamical behavior of the HIV. The viruses are produced from four types of infected cells: short-lived infected $CD4^+$T cells, long-lived chronically infected $CD4^+$T cells, short-lived infected macrophages and long-lived chronically infected macrophages. The drug efficacy is assumed to be different for the two types of target cells. The HIV-target incidence rate is given by bilinear and saturation functional response while, for the third model, both HIV-target incidence rate and neutralization rate of viruses are given by nonlinear general functions. We show that the solutions of the proposed models are nonnegative and ultimately bounded. We derive two threshold parameters which fully determine the positivity and stability of the three steady states of the models. Using Lyapunov functionals, we established the global stability of the steady states of the models. The theoretical results are confirmed by numerical simulations.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.9
• /
• pp.670-677
• /
• 1987

The robustness and stability properties for a model reference adaptive control system with plant uncertainty are considered in this paper, using input-output stability theory. An error model for a typical adaptive control structure is extended to unmodelled dynamics in the plant model and then, the strictly positive real condition for global stability is examined. In general, since this condition can be easily violated due to unmodelled dynamics, a modified compensator which can be guaranteed Hev e SPR is introduced in the plant model and the effectiveness for the given structure is also given.

• 제어로봇시스템학회:학술대회논문집
• /
• /
• pp.1987-1992
• /
• 2004

A Variable Structure Model Reference Adaptive Controller (VS-MRAC) using state Variables is proposed for single input multi output systems. . The structure of the switching functions is designed based on stability requirements, and global exponential stability is proved. Transient behavior is analyzed using sliding mode control and shows perfect model following at a finite time. The effect of input disturbances on stability and transients is investigated and shows preference to the conventional MRAC schemes with integral adaptation law. Sliding surfaces are independent of system parameters and therefore VS-MRAC is insensitive to system parameter variations. Simulation is presented to clear the theoretical results.

• Bulletin of the Korean Mathematical Society
• /
• v.55 no.1
• /
• pp.319-330
• /
• 2018

This paper is concerned with the global asymptotic stability of strong solutions for a class of semilinear evolution equations with nonlocal initial conditions on infinite interval. The discussion is based on analytic semigroups theory and the gradually regularization method. The results obtained in this paper improve and extend some related conclusions on this topic.