• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.387-401
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• 2006

This paper deals with the problem of a ratio-dependent prey- predator model with combined harvesting. The existence of steady states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been considered. The problem of optimal harvest policy is then solved by using Pontryagin's maximal principle.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.467-471
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• 1998

A mathematical model is developed to predict the fatigue notch factor of butt welds subject to number of parameters such as weld geometry, residual stresses under dynamic combined loading conditions (tensile and bending). Linear elastic fracture mechanics, finite element analysis, dimensional analysis and superposition approaches are used for the modelling. The predicted results are in good agreement with the available experimental data. As a result, scatters of the fatigue data can be significantly reduced by plotting S-N curve as ($S{\cdot}K_f$) vs. N.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.857-860
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• 2006

In the present study, the method and procedure for analysis of impact damage behavior for concrete under penetration and perforation of projectile is investigated. Conservation law, equation of motion, initial and boundary conditions, and FEM formulation are introduced and derived respectively. Specially, the constitutive equation which rate-dependent damage combined with rate-dependent plasticity within the appropriate framework of theory of thermodynamics is examined. This paper aimed at the review with respect to impact damage models for concrete to develop that model. This paper is a basis research for the development of impact damage model for concrete.

• Communications of the Korean Mathematical Society
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• v.20 no.3
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• pp.589-602
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• 2005

We present the numerical algorithm for the model for high-strain rate deformation in hyperelastic-viscoplastic materials based on a fully conservative Eulerian formulation by Plohr and Sharp. We use a hyperelastic equation of state and the modified Steinberg and Lund's rate dependent plasticity model for plasticity. A two-dimensional approximate Riemann solver is constructed in an unsplit manner to resolve the complex wave structure and combined with the second order TVD flux. Numerical results are also presented.

• Journal of Korean Institute of Industrial Engineers
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• v.11 no.2
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• pp.47-56
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• 1985

This paper considers a two-product three-facility production planning model, where facility 1 produces product 1 to satisfy its own market requirements and supplies input to facility 2, and facility 2 requires another input from facility 3 (outside supplier). The objective is to determine the optimal production amount in each period in order to satisfy the dynamic demands on time, which minimizes the total cost of production and storage. The set-up cost is incurred jointly from the multi-facility operations.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1991.07a
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• pp.6-10
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• 1991

The bottom friction model of combined wave-current flow developed by Bijker, Yoo and O'Conner (hereafter it is called BYO model) is fully based on the Prandtl's mixing length theory. Although the Prandtl's theory is dependant on some rationalism, it is widely recognized that the theory is generally acceptable for the description of any turbulent flow.(omitted)

• Journal of Information Processing Systems
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• v.14 no.2
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• pp.487-498
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• 2018

The purpose of the high-speed railway construction is to better satisfy passenger travel demands. Accordingly, the design of the train working plan must also take a full account of the interests of passengers. Aiming at problems, such as the complex transport organization and different speed trains coexisting, combined with the existing research on the train working plan optimization model, the multiobjective bi-level programming model of the high-speed railway passenger train working plan was established. This model considers the interests of passengers as the center and also takes into account the interests of railway transport enterprises. Specifically, passenger travel cost and travel time minimizations are both considered as the objectives of upper-level programming, whereas railway enterprise profit maximization is regarded as the objective of the lower-level programming. The model solution algorithm based on genetic algorithm was proposed. Through an example analysis, the feasibility and rationality of the model and algorithm were proved.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.1-6
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• 2017

Total capacity of pumped hydro storage(PHS) in Korean power system reaches 4,700MW, though the share of it is about 4.56% of total capacity The Unit Commitment program, E-terracommit which is used for the operational purpose by KPX, includes the PHS model. But the model has a defect that it does not include the information of water level of upper reservoir. Therefore two types of improved the PHS models are represented in this paper. The first model is a optimized model by connecting the upper reservoir water level to the non-spinning reserve. The other model is to have priority allocate both the PHS and combined cycle generator for non-spinning reserve. The proposed two models and the E-terracommit model is compared and resulting to have improvement in estimating non-spinning reserve when using the proposed models.

• Steel and Composite Structures
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• v.47 no.5
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• pp.587-599
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• 2023

The establishment of a hysteretic model which can accurately predict the hysteretic characteristics of the stud connection is of utmost importance for the seismic assessment of composite structures. In this paper, the Bouc-Wen-Baber-Noori(BWBN) model was adopted to describe the typical hysteretic characteristics of stud connections. Meanwhile, the Newton-Raphson iterative procedure and the Backward Euler method were used to determine the restoring force, and the Genetic Algorithm was employed to identify the parameters of the BWBN model based on the experimental data consisting of eight specimens. The accuracy of the identified parameters was demonstrated by comparison with the experimental data. Finally, prediction equations for the BWBN model parameters were developed in terms of the physical parameters of stud connections, which provides an approach to get the hysteretic response of stud connections conveniently.

• Structural Monitoring and Maintenance
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• v.10 no.2
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• pp.175-190
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• 2023

This article aims to quantitatively predict the snowmelt in extreme cold regions, considering a combination of grayscale and neural models. The traditional non-equidistant GM(1,1) prediction model is optimized by adjusting the time-distance weight matrix, optimizing the background value of the differential equation and optimizing the initial value of the model, and using the BP neural network for the first. The adjusted ice forecast model has an accuracy of 0.984 and posterior variance and the average forecast error value is 1.46%. Compared with the GM(1,1) and BP network models, the accuracy of the prediction results has been significantly improved, and the quantitative prediction of the ice sheet is more accurate. The monitoring and maintenance of the structure by quantitative prediction model by gray models was clearly demonstrated in the model.