• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.8-14
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• 2016

Medical bed head consoles (BHC) are generally used to increase the efficiency of medical equipment and speed the medical treatment response time. The BHC design has been consistently improved including a movable shelf unit that is embedded to mount stably medical instruments on the lower part of the main console. The cost of a BHC can be reduced through design optimization to limit the overall weight. However, as the size of a head console might decrease due to design optimization, the BHC deflection could be increased. In this study, multi-objective optimal design was adopted to consider this BHC design problem. In order to reduce the cost of optimization planning, an approximate model was applied for the design optimization. In the context of approximate optimization, we used the response surface method and non-dominant sorting genetic algorithm developed from various fields. Multi-objective optimal solutions were also compared with a single objective optimal design.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.828-834
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• 1989

On-Line optimization of process units has heretofore been restricted to the individual equipment level using linear approximate models. The advent of the low cost, high speed micro-computer coupled with the speed and robustness of an equation based exact simulator is making real-time optimization of entire process units a reality. The resultant implications for a decision system applied to day-to-day operations, point to a significant change in the way process plants will be managed in the future.

• Journal of the Korea Society of Computer and Information
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• v.19 no.9
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• pp.161-168
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• 2014

The optimal solution of minimum cost for aircraft landing problem(ALP) is very difficult problem because the approached aircraft are random time interval. Therefore this problem has been applied by various meta heuristic methods. This paper suggests O(nlog n) polynomial time heuristic algorithm to obtain the optimal solution for ALP. This algorithm sorts the target time of aircraft into ascending order. Then we apply the optimization of change the landing sequence take account of separation time and the cost of landing. For the Airland1 through Airland8 of benchmark data of ALP, we choose 25 data until the number of runway m that the total landing cost is 0. We can be obtain the optimal solution for all of the 25 data. Especially we can be improve the known optimal solution for m = 1of Airland8.

• International Journal of Control, Automation, and Systems
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• v.3 no.4
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• pp.524-532
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• 2005

This paper concerns delay-dependent guaranteed cost control (GCC) problem for a class of linear state-delayed systems with norm-bounded time-varying parametric uncertainties. By incorporating the free weighing matrix approach developed recently, new delay-dependent conditions for the existence of the guaranteed cost controller are presented in terms of matrix inequalities for both nominal state-delayed systems and uncertain state-delayed systems. An algorithm involving convex optimization is proposed to design a controller achieving a suboptimal guaranteed cost such that the system can be stabilized for all admissible uncertainties. Through numerical examples, it is shown that the proposed method can yield less guaranteed cost than the existing delay-dependent methods.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.3
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• pp.194-202
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• 2009

In this paper, we address an optimization problem and a case study for minimizing the cost of inspections incurred throughout an inspection system, which includes a K-stage inspection system, a source inspection shop, and a re-inspection shop. In order to formulate the inspection cost function, we make a time-based flow analysis between nodes (or shops), and derive the limiting sizes of flows between nodes and limiting defective rates by solving a set of nonlinear balance equations. It turns out that the number of items reworked throughout the inspection system is invariant irrespective of the defective rate of items moved through the K-stage inspection system. Hence we define the inspection cost as the total number of items inspected, and we provide an enumeration method for determining an optimal value of K which minimizes the number of items inspected.

• Proceedings of the Korean Statistical Society Conference
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• 2005.11a
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• pp.73-78
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• 2005

This paper considers a preventive maintenance policy following the expiration of renewing warranty, Most preventive maintenance models assume that each PM costs a fixed predetermined amount regardless of the effectiveness of each PM. However, it seems more reasonable to assume that the PM cost depends on the degree of effectiveness of the PM activity. In this paper we consider a periodic preventive maintenance policy following the expiration of renewing warranty when the PM cost is an increasing function of the PM effect. The optimal number and period for the periodic PM policy with effect dependent cost that minimize the expected cost rate per unit time over an infinite time span are obtained.

• IE interfaces
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• v.16 no.1
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• pp.27-33
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• 2003

The maintenance cost in K Steelworks has been continuously increased in proportion to the production cost. However, there seems to be a possibility of reducing cost through the optimization of maintenance actions. The failure types of the equipment in steelworks ate various with different failure cost. Thus the failure rate and cost of each type of failures should be considered simultaneously when the optimum maintenance period is to be determined. It is considered that the equipment undergoes periodic replacement and a specified number of incomplete preventive maintenance actions are performed during a replacement period. Assuming that the time to failure follows a Weibull distribution, the parameters of the failure rate are estimated using the maximum likelihood estimation. The optimal replacement period is determined to minimize the average cost per unit time. As the result of analysis it is suggested that the existing maintenance period for a hot-rolling equipment can be extended significantly.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.95-112
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• 1999

In this research, it is proposed that optimization method is introduced and applied to the design of pipeline system in multi-regional water supply project, which has been constructed to settle the regional unbalance problems of available water resources. For the purpose, interface programs are developed to integrate linear programming model and KYPIPE model which is used for optimization and hydraulic analysis, respectively. The developed program is applied to the pipeline system design of multi-regional water supply project. The optimal diameters from the application of linear programming technique are compared with those from conventional method that is time-consuming and tedious trail and error process. Since the conventional design largely depends upon the experience of designers and the results of general hydraulic analysis, it can not be reasonable and consistent. The application of linear programming technique can make it possible to design pipeline system optimally by using same design factors of general hydraulic models. The model can select commercial discrete pipe diameter as optimal size by using pipe length as decision variables. The developed model is applied to Pohang multi-regional water supply system design with two different objective functions, which are initial construction cost and annual cost including electric cost. As results, it is calculated that the initial construction cost of 1,449,740 thousand won is saved and annual cost of 128,951 thousand won is saved for a year within study year. Also, the optimal site of pump station is selected on 5th pipe, which is located between the diverging junction to Kangdong(2) province and the diverging junction to Cheonbuk province. It is explained that pump cost is less than pipe cost in this application case study due to little pump station scale. In the case of water supply with large pump capacity, it is reasonal that the increase of pipe size is more efficient instead the increase of pump station capacity to save annual cost.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.81-86
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• 2014

The analysis of the cost optimization and the total demand weight of 9% Ni-steel plates for installing shell stiffeners in the side wall of the large capacity LNG storage tank are carried out in order to reduce the costs of the plates for stiffeners. This study can be possible for developing the calculation program which evaluates the bill-of-material for stiffeners to reduce the manual calculation time of tank designer, and to enable the estimation of weight and cost for various plate width. The results show that the demand weight and cost are reduced as the plate width is wider. Nevertheless, both the weight and the cost with plate width for stiffeners should be compared and evaluated to obtain the optimum cost time to time because of various cost incremental factors of plates such as transportation and handling cost, etc.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.11a
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• pp.309-314
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• 2006

The linear Consecutive-k-out-of-n:F system consists of n component ordered linearly and fail if and only if at least k consecutive components fail. We assume that the components are independent and identical exponentially distributed. This paper develops a model to calculate the expected cost per unit time of a linear consecutive-k-out-of-n:F system. The optimization problem we consider regards the choice of the system structure parameter k to minimized the expected cost per unit time.