• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.493-504
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• 2011

The present paper presents a genetic algorithm (GA) to maximize social welfare and perform congestion management by optimally placing and sizing one Thyristor-Controlled Series Capacitor (TCSC) device in a double-sided auction market. Simulation results, with line flow constraints before and after the compensation, are compared through the Sequential Quadratic Programming SQP method, and are used to analyze the effect of TCSC on the congestion levels of modified IEEE 14-bus and 30-bus test systems. Quadratic, smooth and nonsmooth (with sine components due to valve point loading effect) generator cost curves, and quadratic smooth consumer benefit functions are considered. The main aims of the present study are the inclusion of customer benefit in the social welfare maximization and congestion management objective function, the consideration of nonsmooth generator characteristics, and the optimal locating and sizing of the TCSC using real code-based GA to guarantee fast convergence to the best solution.

• Industrial Engineering and Management Systems
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• 제11권3호
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• pp.288-298
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• 2012

Lot sizing and shipment scheduling are two interrelated decisions made by a manufacturing plant and a third-party logistics distribution center. This paper analyzes a dynamic inbound ordering problem and shipment problem with a freight container cost, in which the order size of multiple products and single container type are simultaneously considered. In the problem, each ordered product placed in a period is immediately shipped by some freight containers in the period, and the total freight cost is proportional to the number of containers employed. It is assumed that the load size of each product is equal and backlogging is not allowed. The objective of this study is to simultaneously determine the lot-sizes and the shipment schedule that minimize the total costs, which consist of production cost, inventory holding cost, and freight cost. Because the problem is NP-hard, we propose three meta-heuristic algorithms: a simulated annealing algorithm, a genetic algorithm, and a new population-based evolutionary meta-heuristic called self-evolution algorithm. The performance of the meta-heuristic algorithms is compared with a local search heuristic proposed by the previous paper in terms of the average deviation from the optimal solution in small size problems and the average deviation from the best one among the replications of the meta-heuristic algorithms in large size problems.

• 한국정밀공학회지
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• 제14권3호
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• pp.89-97
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• 1997

A genetic algorithm (GA) is a stochastic direct search strategy that mimics the process of genetic evolution. The GA applied herein works on a population of structural designs at any one time, and uses a structured information exchange based on the principles of natural selection and wurvival of the fittest to recombine the most desirable features of the designs over a sequence of generations until the process converges to a "maximum fitness" design. Principles of genetics are adapted into a search procedure for structural optimization. The methods consist of three genetics operations mainly named selection, cross- over and mutation. In this study, a method of finding the optimum topology of truss/beam structure is pro- posed by using the GA. In order to use GA in the optimum topology problem, chromosomes to FEM elements are assigned, and a penalty function is used to include constraints into fitness function. The results show that the GA has the potential to be an effective tool for the optimal design of structures accounting for sizing, geometrical and topological variables.variables.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.1-12
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• 2009

In recent years, integration of new distributed generation (DG) technology in distribution networks has become one of the major management concerns for professional engineers. This paper presents a dynamic methodology of optimal allocation and sizing of DG units for a given practical distribution network, so that the cost of active power can be minimized. The approach proposed is based on a combined Genetic/Fuzzy Rules. The genetic algorithm generates and optimizes combinations of distributed power generation for integration into the network in order to minimize power losses, and in second step simple fuzzy rules designs based upon practical expertise rules to control the reactive power of a multi dynamic shunt FACTS Compensator (SVC, STATCOM) in order to improve the system loadability. This proposed approach is implemented with the Matlab program and is applied to small case studies, IEEE 25-Bus and IEEE 30-Bus. The results obtained confirm the effectiveness in sizing and integration of an assigned number of DG units.

• 한국의류학회지
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• 제31권3호
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• pp.364-375
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• 2007

The propose of this study is to develop the optimal sizing system of ready-to-wear far elementary school boys using a newly invented statistical technique. The body measurements was classified by the method that equalizes the distribution of the subjects using the probability density function, to theoretically systemize a method to determine a size range of ready-to-wear for elementary school boys between 7 to 12 yeiws old. The results were as follows: 1. Height group includes 9 types of heights: 115, 120, 125, 130, 135, 140, 145, 150 and 155. 2. In the case of short children's groups, the variance in bust girth and waist girth is narrow. The people cluster together around the average. The size deviation of ready-to-wear is small. 3. In the case of tall children's groups, the variance in bust girth and waist girth is wide. The people spread widely around the average. The size deviation of ready-to-wear is large. 4. The optimal size system is suggested considering the weight of growth exponent of children according to their respective ages. Clothing companies can selectively choose sizes that meet the target of their brands. 5. It suggests the body sizes chart, which based on their means by the middle size children for each height group, so that clothing companies make use of it.

• 대한산업공학회지
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• 제17권1호
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• pp.29-35
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• 1991

This paper deals with a production-inventory model for two-stage batch production system. We propose a lot-sizing scheme which combines the integer multiple lot requirements (IMLR) policy and the integer split lot requirements (ISLR) policy. An iterative search procedure for optimal decision variables is presented and numerical examples are solved to illustrate the validity of the model. The results show that the proposed scheme outperforms the existing policies.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2007년도 추계학술대회 및 정기총회
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• pp.7-11
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• 2007

This paper considers a shipment planning of products from manufacturers to a third-party warehouse for demands with production time windows where a demand must be replenished in its time window. The underling lot-sizing model also assumes cargo delivery cost in each inbound replenishment to the warehouse. For this model, an optimal O($nT^4$) is presented where n is the number of demands and T is the length of the planning horizon.

• 한국생산제조학회지
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• 제8권1호
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• pp.60-66
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• 1999

This study is to develop design sensitivity analysis method based on continuum theory for the actual buckling load of vehicle passenger compartment with respect to sizing design variables. For nonlinear structural analysis, both geometric and material nonlinear effects are considered. The total Lagrangian formulation for incremental equilibrium analysis and one-point linear eigenvalue problem for buckling analysis are utilized. Numerical methods are presented to evaluate design sensitivity expressions, using structural analysis results from FEM code. Optical design of vehicle passenger compartment with buckling constraint solved using Gradient projection method.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.28-35
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• 1997

A new approach concurrent transistor sizing and buffer insertion for low power optimization is proposed in this paper. The method considers the tradeoff between upsizing transistors and inserting buffers and chooses the solution with the lowest possible power and area cost. It operates by analyzing the feasible region of the cost-delay curves of the unbuffered and buffered circuits. As such the feasible region of circuits optimized by our method is extended to encompass the envelop of cost-delay curves which represent the union of the feasible regions of all buffered ad unbuffered versions of the circuit. The method is efficient and tunable in that optimality can be traded for compute time and as a result it can in theory near optimal results.

• 산업경영시스템학회지
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• 제44권2호
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• pp.24-35
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• 2021

Due to increasing awareness on the treatment of end-of-use/life products, disassembly has been a fast-growing research area of interest for many researchers over recent decades. This paper introduces a novel lot-sizing problem that has not been studied in the literature, which is the service-parts lot-sizing with disassembly option. The disassembly option implies that the demands of service parts can be fulfilled by newly manufactured parts, but also by disassembled parts. The disassembled parts are the ones recovered after the disassembly of end-of-use/life products. The objective of the considered problem is to maximize the total profit, i.e., the revenue of selling the service parts minus the total cost of the fixed setup, production, disassembly, inventory holding, and disposal over a planning horizon. This paper proves that the single-period version of the considered problem is NP-hard and suggests a heuristic by combining a simulated annealing algorithm and a linear-programming relaxation. Computational experiment results show that the heuristic generates near-optimal solutions within reasonable computation time, which implies that the heuristic is a viable optimization tool for the service parts inventory management. In addition, sensitivity analyses indicate that deciding an appropriate price of disassembled parts and an appropriate collection amount of EOLs are very important for sustainable service parts systems.