• Journal of Electrical Engineering and Technology
• /
• v.3 no.2
• /
• pp.218-223
• /
• 2008

A new Pareto-optimal design algorithm, requiring least computational work, is proposed for a single phase AC solenoid actuator with multi-design-objectives: maximizing holding force and minimizing eddy current loss simultaneously. In the algorithm, the design space is successively reduced by a suitable factor, as iteration repeats, with the center of pseudo-optimal point. At each iteration, the objective functions are approximated to a simple second-order response surface with the CCD sampling points generated within the reduced design space, and Pareto-optimal solutions are obtained by applying($1+{\lambda}$) evolution strategy with the fitness values of Pareto strength.

• Journal of Korean Institute of Industrial Engineers
• /
• v.22 no.4
• /
• pp.533-549
• /
• 1996

This paper is concerned with a sequencing problem in mixed model assembly lines, which is important to efficient utilization of the lines. In the problem, we deal with the two objectives of minimizing the risk of stoppage and leveling part usage, and consider sequence-dependent setup time. In this paper, we present a genetic algorithm(GA) suitable for the multi-objective optimization problem. The aim of multi-objective optimization problems is to find all possible non-dominated solutions. The proposed algorithm is compared with existing multi-objective GAs such as vector evaluated GA, Pareto GA, and niched Pareto GA. The results show that our algorithm outperforms the compared algorithms in finding good solutions and diverse non-dominated solutions.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.52.1-52
• /
• 2001

System establishment using a network may be a decisive factor both for creating a flexible production system and increasing reliability and serve as a basis for setting up of a management system that will make the designing, maintenance, and repair easier. It is therefore imperative to develop a protocol which is simple to use for communications and connections among different devices. The objectives of this study is to establish communications protocol stack that will enable to conduct an effective monitoring of production facilities and to secure flexibility of reduction control system, and to improve the working ratio of the production facilities by centralization of communications system through effective collecting and storing of the diversified data of multi-type and multi-device production facilities.

• International journal of steel structures
• /
• v.18 no.5
• /
• pp.1598-1606
• /
• 2018

An integrated optimal structural design method for a diagrid structure and control device was developed. A multi-objective genetic algorithm was used and a 60-story diagrid building structure was developed as an example structure. Artificial wind and earthquake loads were generated to assess the wind-induced and seismic responses. A smart tuned mass damper (TMD) was used as a structural control system and an MR (magnetorheological) damper was employed to develop a smart TMD (STMD). The multi-objective genetic algorithm used five objectives including a reduction of the dynamic responses, additional stiffness and damping, mass of STMD, capacity of the MR damper for the integrated optimization of a diagrid structure and a STMD. From the proposed method, integrated optimal designs for the diagrid structure and STMD were obtained. The numerical simulation also showed that the STMD provided good control performance for reducing the wind-induced and seismic responses of a tall diagrid building structure.

• Smart Structures and Systems
• /
• v.22 no.1
• /
• pp.81-94
• /
• 2018

Automatic Generation Control (AGC) has functionally controlled the interchange power flow in order to suppress the dynamic oscillations of frequency and tie-line power deviations as a perturbation occurs in the interconnected multi-area power system. Furthermore, Flexible AC Transmission Systems (FACTS) can effectively assist AGC to more enhance the dynamic stability of power system. So, Static Synchronous Series Compensator (SSSC), one of the well-known FACTS devices, is here applied to accurately control and regulate the load frequency of multi-area multi-source interconnected power system. The research and efforts made in this regard have caused to introduce the Fractional Order Proportional Integral Derivative (FOPID) based SSSC, to alleviate both the most significant issues in multi-area interconnected power systems i.e., frequency and tie-line power deviations. Due to multi-objective nature of aforementioned problem, suppression of the frequency and tie-line power deviations is formularized in the form of a multi-object problem. Considering the high performance of Multi Objective Bees Algorithm (MOBA) in solution of the non-linear objectives, it has been utilized to appropriately unravel the optimization problem. To verify and validate the dynamic performance of self-defined FOPID-SSSC, it has been thoroughly evaluated in three different multi-area interconnected power systems. Meanwhile, the dynamic performance of FOPID-SSSC has been accurately compared with a conventional controller based SSSC while the power systems are affected by different Step Load Perturbations (SLPs). Eventually, the simulation results of all three power systems have transparently demonstrated the dynamic performance of FOPID-SSSC to significantly suppress the frequency and tie-line power deviations as compared to conventional controller based SSSC.

• Journal of Korea Water Resources Association
• /
• v.38 no.9 s.158
• /
• pp.737-746
• /
• 2005

Optimization is a process that searches an optimal solution to obtain maximum or minimum value of an objective function. Many researchers have focused on effective search algorithms for the optimum but few researches were interested in establishing the objective function. This study compares two approaches for the objective function: one allows a tradeoff among the objectives and the other does not allow a tradeoff by assigning weights for the absolute priority between the objectives. An optimization model using sampling stochastic dynamic programming was applied to these two objective functions and the resulting optimal policies were compared. As a result, the objective function with no tradeoff provides a decision making process that matches practical reservoir operations than that with a tradeoff allowed. Therefore, it is more reasonable to establish the objective function with no a tradeoff among the objectives for multi-purpose dam operation plan in Korea.

• Journal of Korea Water Resources Association
• /
• v.30 no.2
• /
• pp.107-118
• /
• 1997

The Upper Fenhe Reservoir System studied by KOWACO to supply water to Taiyuan City, capital of Shanxi Province in China, is a very complicated one. Many reservoirs will be connected serially and it will be operated as a multi-purpose and multi-criteria system because several objectives and appraisal functions are taken into account regarding system operation. For reservoirs in the system, the critical system operation objectives are to minimize water shortage and reservoir sediment. Furthermore the reservoir system will be jointed with a large-scale pumping system, namely Yellow River Diversion Project. The water development cost in the Yellow River Diversion Project is much higher than that of reservoir system, and around the year 2020 the diversion volume will be twice of the surface water available in the Upper Fenhe Basin. In this study, an optimization technique for connecting the system of reservoirs and pumping station was developed to solve a conjunctive low River Diversion Project. The developed scheme includes a suggestion on the combining methodology of real reservoir system and pumping system using imaginary reservoir concept for the Yellow River Diversion Project, and practical examples to the minimization problem of the Yellow River diversion satisfying other reservoir operation objectives.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1998.10a
• /
• pp.211-217
• /
• 1998

Many practical control problems for the complex, uncertain or large-scale plants, need to simultaneously achieve a number of objectives, which may conflict or compete with each other. If the conventional optimization methods are applied to solve these control problems, the solution process may be time-consuming and the resulting solution would ofter lose its original meaning of optimality. Nevertheless, the human operators usually performs satisfactory results based on their qualitative and heuristic knowledge. In this paper, we investigate the control strategies of the human operators, and propose a fuzzy model-based multi-objective satisfactory controller. We also apply it to the automatic train operation(ATO) system for the magnetically levitated vehicles(MAGLEV). One of the human operator's strategies is to predict the control result in order to find the meaningful solution. In this paper, Takagi-Sugeno fuzzy model is used to simulated the prediction procedure. Another str tegy is to evaluate the multiple objectives with respect to their own standards. To realize this strategy, we propose the concept of a satisfactory solution and a satisfactory control scheme. The MAGLEV train is a typical example of the uncertain, complex and large-scale plants. Moreover, the ATO system has to satisfy multiple objectives, such as seed pattern tracking, stop gap accuracy, safety and riding comfort. In this paper, the speed pattern tracking controller and the automatic stop controller of the ATO system is designed based on the proposed control scheme. The effectiveness of the ATO system based on the proposed scheme is shown by the experiments with a rotary test bed and a real MAGLEV train.

• Korean Journal of Acupuncture
• /
• v.28 no.1
• /
• pp.1-13
• /
• 2011

Objectives : The object of this study is to evaluate and develop the system that reflects acupoints electrical properties by the multi-frequency using the SPAC (Single Power Alternative Current) stimulation method based on BIA (Bioelectrical impedance method). Methods : The 12 channel meridian impedance measurement system (MIMS) was designed, which sets multi-frequency with 10 steps (1~10kHz). To check acupoints electrical properties, impedance of acupoints were measured from 11 acupoints selected from the LU and ST meridians. Results : Regarding distribution of measurement values by multi-frequencies, we found the lowest response at 1kHz was in common. But frequency bands which represent the highest response at each acupoint were various. Measurement values of each acupoint by multi-frequencies were expressed similar distribution (P<0.05). Also we could check same frequency band which showed the highest response at left/right equal acupoints (P<0.05). Conclusions : Through change of acupoints electrical properties by multi-frequency stimulation, we checked oriental medical diagnostic possibilities by using this system. We would progress variable clinical trials with this system for oriental medical diagnosis.

• Earthquakes and Structures
• /
• v.23 no.1
• /
• pp.35-57
• /
• 2022

This article presents a computationally efficient framework for multi-objective seismic design optimization of steel moment-resisting frame (MRF) structures based on the nonlinear dynamic analysis procedure. This framework employs the uniform damage distribution philosophy to minimize the weight (initial cost) of the structure at different levels of damage. The preliminary framework was recently proposed by the authors based on the single excitation and the nonlinear static (pushover) analysis procedure, in which the effects of record-to-record variability as well as higher-order vibration modes were neglected. The present study investigates the reliability of the previous framework by extending the proposed algorithm using the nonlinear dynamic design procedure (optimization under multiple ground motions). Three benchmark structures, including 4-, 8-, and 12-story steel MRFs, representing the behavior of low-, mid-, and high-rise buildings, are utilized to evaluate the proposed framework. The total weight of the structure and the maximum inter-story drift ratio (IDRmax) resulting from the average response of the structure to a set of seven ground motion records are considered as two conflicting objectives for the optimization problem and are simultaneously minimized. The results of this study indicate that the optimization under several ground motions leads to almost similar outcomes in terms of optimization objectives to those are obtained from optimization under pushover analysis. However, investigation of optimal designs under a suite of 22 earthquake records reveals that the damage distribution in buildings designed by the nonlinear dynamic-based procedure is closer to the uniform distribution (desired target during the optimization process) compared to those designed according to the pushover procedure.