• Journal of computational fluids engineering
• /
• v.13 no.3
• /
• pp.51-61
• /
• 2008

The SMAC (Simplified Marker And Cell) algorithm is extended for an application to thermal non-equilibrium two-phase flows in light water nuclear reactors (LWRs). A two-fluid three-field model is adopted and a multi-dimensional unstructured grid is used for complicated geometries. The phase change and the time derivative terms appearing in the continuity equations are implemented implicitly in a pressure correction equation. The energy equations are decoupled from the momentum equations for faster convergence. The verification of the present numerical method was carried out against a set of test problems which includes the single and the two-phase flows. The results are also compared to those of the semi-implicit ICE method, where the energy equations are coupled with the momentum equation for pressure correction.

• Journal of the Korea Society of Computer and Information
• /
• v.23 no.3
• /
• pp.25-31
• /
• 2018

In this paper, we consider the game theoretic approach to investigate the transmit power optimization problem where D2D users share the uplink of the cellular system. Especially, we formulate the transmit power optimization problem as a non cooperative power control game. In the user wide sense, each user may try to select its transmit power level so as to maximize its utility in a selfish way. In the system wide, the transmit power levels of all users eventually converge to the unique point, called Nash Equilibrium. We first formulate the transmit power optimization problem as a non cooperative power control game. Next, we examine the existence of Nash Equilibrium. Finally, we present the numerical example that shows the convergence to the unique transmit power level.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.7
• /
• pp.2281-2301
• /
• 2014

In wireless ad hoc networks the nodes focus on achieving the maximum SINR for efficient data transmission. In order to achieve maximum SINR the nodes culminate in exhausting the battery power for successful transmissions. This in turn affects the successful transmission of the other nodes as the maximum transmission power opted by each node serves as a source of interference for the other nodes in the network. This paper models the choice of power for each node as a non cooperative game where the throughput of the network with respect to the consumption of power is formulated as a utility function. We propose an adaptive pricing scheme that encourages the nodes to use minimum transmission power to achieve target SINR at the Nash equilibrium and improve their net utility in multiuser scenario.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.54 no.4
• /
• pp.259-266
• /
• 2005

This paper presents a therapy that uses a constant drug dosage for leading HIV-infected patient to LTNP (Long-Term Non-Progressor). Based on analysis of CTLp (Cytotoxic T Lymphocyte precursor) concentration at equilibrium point and its bifurcation, we found the therapy with a drug whose efficacy is less than a certain level brings higher CTLp concentration at the equilibrium point. We observed a treatment with constant drug dosage whose efficacy is less than full treatment may lead HIV-infected patient to LTNP. It turns out that the treatment whose efficacy is less than full treatment is better in the point of performance on controllability.

• Bulletin of the Korean Mathematical Society
• /
• v.50 no.1
• /
• pp.25-36
• /
• 2013

By using some existence theorems of maximal elements for a family of set-valued mappings involving a better admissible set-valued mapping under noncompact setting of FC-spaces, we present some non-empty intersection theorems for a family $\{G_i\}_{i{\in}I}$ in product FC-spaces. Then, as applications, some new existence theorems of equilibrium for a system of generalized vector equilibrium problems are proved in product FC-spaces. Our results improve and generalize some recent results.

• Structural Engineering and Mechanics
• /
• v.5 no.5
• /
• pp.577-586
• /
• 1997

In nonlinear finite element stability analysis of structures, the foremost necessary procedure is the computation to precisely locate a singular equilibrium point, at which the instability occurs. The present study describes global and local procedures for the computation of stability points including bifurcation points and limit points. The starting point, at which the procedure will be initiated, may be close to or arbitrarily far away from the target point. It may also be an equilibrium point or non-equilibrium point. Apart from the usual equilibrium path, bypass and homotopy path are proposed as the global path to the stability point. A local iterative method is necessary, when it is inspected that the computed path point is sufficiently close to the stability point.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.1
• /
• pp.62-67
• /
• 2003

An important aspect of the study of power system markets involves the assessment of strategic behavior of participants for maximizing their profits. In models of imperfect competition of a deregulated electricity system, the key task is to find the Nash equilibrium. In this paper, the bimatrix approach for finding Nash equilibria in electricity markets is investigated. This approach determines pure and mixed equilibria using the complementarity pivot algorithim. The mixed equilibrium in the matrix approach has the equal number of non-zero property. This property makes it difficult to reproduce a smooth continuous distribution for the mixed equilibrium. This paper proposes an algorithm for adjusting the quantization value of discretization to reconstruct a continuous distribution from a discrete one.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.1
• /
• pp.16-22
• /
• 2017

In order to reduce costs of electricity energy at periods of peak demand, there has been an exponential interest in Demand Response (DR). This paper discusses the effect on the participants' behavior in response to DR. Under the assumption of perfect competition, the equilibrium point of the electricity market with DR is derived by modeling a DR curve, which is suitable for microeconomic analysis. Cournot model is used to analyze the electricity market of imperfect competition that includes strategic behavior of the generation companies. Strategic behavior with DR makes it harder to compute equilibrium point due to the non-differential function of payoff distribution. This paper presents a solution method for achieving the equilibrium point using the best response function of the strategic players. The effect of DR on the electricity market is illustrated using a test system.

• KIEE International Transactions on Power Engineering
• /
• v.5A no.1
• /
• pp.85-92
• /
• 2005

In this paper, Nash equilibriums of generation markets are investigated using a game theory application for simplified competitive electricity markets. We analyze the characteristics of equilibrium states in N-company spot markets modeled by uniform pricing auctions and propose a new method for obtaining Nash equilibriums of the auction. We assume that spot markets are operated as uniform pricing auctions and that each generation company submits its bids into the auction in the form of a seal-bid. Depending on the bids of generation companies, market demands are allocated to each company accordingly. The uniform pricing auction in this analysis can be formulated as a non-cooperative and static game in which generation companies correspond to players of the game. The coefficient of the bidding function of company-n is the strategy of player-n (company-n) and the payoff of player-n is defined as its profit from the uniform price auction. The solution of this game can be obtained using the concept of the non-cooperative equilibrium originating from the Nash idea. Based on the so called residual demand curve, we can derive the best response function of each generation company in the uniform pricing auction with N companies, analytically. Finally, we present an efficient means to obtain all the possible equilibrium set pairs and to examine their feasibilities as Nash equilibriums. A simple numerical example with three generation companies is demonstrated to illustrate the basic idea of the proposed methodology. From this, we can see the applicability of the proposed method to the real-world problem, even though further future analysis is required.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.2
• /
• pp.321-324
• /
• 2004