• Journal of Korean Society of Industrial and Systems Engineering
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• 제19권40호
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• pp.329-339
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• 1996

This study presents the eigen ethnic function and mathematical processing method of human information. Human information can be definded as the overlap area taking the superposition property composed of intuition and sensory in stimulus/response (S/R) model, In S/R model, the intuition and sensory eigen ethnic function acts on the forming of perception. Perception process by the superposition property of intuition and sensory analogy to the basic neural network model. This analogy model extends to the analysis method. As an analysis method, optimal ratio number induced to the golden section ratio. Golden section ratio drived out by diverse source and implicated to the sensory and intuitive context such as beauty, harmony, optimality etc. This numerical orders can be applied to analysing the Perception process and extended to pursue the Potential human behavior, On the basic of proposed applying method, an illustrative mathematical examples are presented.

• Proceedings of the KIPE Conference
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.356-357
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• 2018

Fuel-cell powered Railway Vehicle Propulsion Systems (RVPSs) are highly desirable due to environment friendly characteristics, and high efficiency of fuel cell (FC). Among various types, the faster start-up and optimality to frequent starts and stops of Polymer electrolyte membrane fuel cell (PEMFC) makes it well suited for propulsion systems. A comprehensive model of PEMFC with reflection of multi-physics behavior required to identify and validate its performance in real RVPSs. Thus this paper will model and simulate the PEMFC unit cell model: a detailed reflection of governing laws and account of dynamic conditions.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제32권4호
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• pp.63-71
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• 2009

The traditional portfolio optimization problem is to find an investment plan for securities with reasonable trade-off between the rate of return and the risk. The seminal work in this field is the mean-variance model by Markowitz, which is a quadratic programming problem. Since it is now computationally practical to solve the model, a number of alternative models to overcome this complexity have been proposed. In this paper, among the alternatives, we focus on the Mean Absolute Deviation (MAD) model. More specifically, we developed an algorithm to obtain an optimal portfolio from the MAD model. We showed mathematically that the algorithm can solve the problem to optimality. We tested it using the real data from the Korean Stock Market. The results coincide with our expectation that the method can solve a variety of problems in a reasonable computational time.

• Environmental and Resource Economics Review
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• 제12권3호
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• pp.397-425
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• 2003

This paper develops a simple theoretical model that is consistent with the empirical evidence of an inverted U-shpated relationship between pollution and per capita income, which is so-called environmental Kuznets curve in this literature. Also, by incorporating the issue of environmental externality into an endogenous growth model, I investigate the circumstances under which growth can be sustained with the optimal control of pollution, and hence the sustainable development can be achieved. In order to study the problem of implementing the social optimum in a market economy, I examine the optimality of three different kinds of environmental policy instruments; pollution tax, pollution-permit trading system (pollution voucher), and direct regulation. This paper shows that the optimum can be implemented with a pollution tax or with a voucher system. Also, it is shown that the socially optimal rate of pollution tax should increase proportionally to the growth rate of consumption.

• Steel and Composite Structures
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• 제27권1호
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• pp.27-33
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• 2018

In this study, a mixed-interpolated tensorial component 4 nodes method (MITC4) is treated as a numerical analysis model for topology optimization using multiple materials assigned within Reissner-Mindlin plates. Multi-material optimal topology and shape are produced as alternative plate retrofit designs to provide reasonable material assignments based on stress distributions. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. Mathematical formulation of multi-material topology optimization problem solving minimum compliance is an alternating active-phase algorithm with the Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples illustrate the reliability and accuracy of the present design method for multi-material topology optimization with Reissner-Mindlin plates using MITC4 elements and steel materials.

• Journal of applied mathematics & informatics
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• 제26권3_4호
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• pp.519-530
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• 2008

This paper studies the multi-domain coupled system of one dimensional Arctic temperature field and establishes identification model about the thermodynamic parameters of sea ice (heat storage capacity, density and conductivity) by the so-called output least-square estimate according to the temperature data acquired by a monitor buoy installed in the Arctic ocean. By the optimal control theory, the existence and dependability of weak solution and the identifiability of identification model have been given. Moreover, necessary optimality condition is proposed. Furthermore, the optimal algorithm for the identification model is constructed. By using the optimal thermodynamic parameters of Arctic sea ice, the numerical simulation is implemented, and the numerical results of temperature distribution of Arctic sea ice are demonstrated.

• Industrial Engineering and Management Systems
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• 제16권1호
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• pp.52-63
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• 2017

The inventory level of concurrent spare parts (CSP) has a significant impact on the availability of a weapon system. A failure rate function might be of particular importance in deciding the CSP inventory level. We developed a CSP optimization model which provides a compromise between purchase costs and shortage costs on the basis of the Weibull and the exponential failure rate functions, assuming that a failure occurs according to the (non-) homogeneous Poisson process. Computational experiments using the data obtained from the Korean Navy identified that, throughout the initial provisioning period, the optimization model using the exponential failure rate tended to overestimate the optimal CSP level, leading to higher purchase costs than the one using the Weibull failure rate. A Pareto optimality was conducted to find an optimal combination of these two failure rate functions as input parameters to the model, and this provides a practical solution for logistics managers.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.80-89
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• 2014

A stochastic optimal power flow (S-OPF) model considering uncertainties of load and wind power is developed based on chance constrained programming (CCP). The difficulties in solving the model are the nonlinearity and probabilistic constraints. In this paper, a limit relaxation approach and an iterative learning control (ILC) method are implemented to solve the S-OPF model indirectly. The limit relaxation approach narrows the solution space by introducing regulatory factors, according to the relationship between the constraint equations and the optimization variables. The regulatory factors are designed by ILC method to ensure the optimality of final solution under a predefined confidence level. The optimization algorithm for S-OPF is completed based on the combination of limit relaxation and ILC and tested on the IEEE 14-bus system.

• Journal of the Korean Regional Science Association
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• 제13권2호
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• pp.75-92
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• 1997

This paper is concerned with an estimation of optimal investment of road sector in 1996-2005. The main method is a Computable General Equilibrium (CGE) Model for Korea in which the optimal solution is derived in a recursively dynamic path. The model is composed of three main modules: the supply, the demand and the price. In this paper, the investment demand for the road is optimized with subject to national economic growth and price inflation. If the annual inflation level and the economic growth rate during 1996-2005 are set to 4.5%-5.0% and 6.0%-6.5% respectively, the optimal demand for the road investment is estimated as 155.1-180.1 trillion Won or 3.33%-3.89% of the GDP for ten years. It implies that the additional increase of the road investment by 0.61%-1.15% of the GDP is required for sustainable economic development, since the share of the road investment in the GDP of the latest 5 years has stayed around 2.27%. However, it is necessary to reduce construction investments on housing as well as to promote private financing of the road in order to maximize an efficiency of resource allocation.

• International Journal of Reliability and Applications
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• 제18권1호
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• pp.9-20
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• 2017

In this paper, we consider a renewable repair-replacement warranty strategy with age-dependent minimal repair service and propose an optimal maintenance model during post-warranty period. Such model implements the repair time limit under warranty and follows with a certain form of system maintenance strategy when the warranty expires. The expected cost rate is investigated per unit time during the life period of the system as for the standard for optimality. Based on the cost design defined for each failure of the system, the expected cost rate is derived during the life period of the system, considering that a renewable minimal repair-replacement warranty strategy with the repair time limit is provided to the customer under warranty. When the warranty is finished, the maintenance of the system is the customer's responsibility. The life period of the system is defined and the expected cost rate is developed from the viewpoint of the customer's perspective. We obtain the optimal maintenance strategy during the maintenance period by minimizing such a cost rate after a warranty expires. Numerical examples using field data are shown to exemplify the application of the methodologies proposed in this paper.