• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.595-597
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• 2002

This paper presents an optimum design, which is able to determine optimal geometric and electric parameters of Switched Reluctance Motor so as to fit respective operating conditions specified in various industrial fields. Those works describe an approach to maximize the average torque while keeping the torque ripple within 10${\sim}$100(%) of respective limited values. This optimum design is obtained by uniting an optimization algorithm of PQRSM to a time stepping finite element method.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1143-1145
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• 2002

IPMSM (Interior Permanent Magnet Synchronous Motor) is widely used in many applications such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives. In order to maximize the efficiency in such applications, this paper is proposed the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM. The proposed control algorithm is applied to IPMSM drive system, the operating characteristics controlled by efficiency optimization control are examined in detail by simulation.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.6
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• pp.385-393
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• 2017

As the use of mobile devices such as smartphones increases, there is growing interest on the benefits of virtualization in embedded systems. Full virtualization has the advantage of running the guest virtual machine without modifying the guest operating system. However, full virtualization suffers slow execution speed due to the cost of context switching between the virtual machines and the virtual machine monitor. In this paper, we propose a translated block and context switching optimization to improve the guest execution speed in the embedded system. As a result, the improved dynamic binary translator is up to 5.95 times faster than the native execution. Performance degradation is less than that of the other virtualization system.

• Journal of Information Technology Services
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• v.18 no.5
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• pp.155-164
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• 2019

With the emergence of new ICT technologies, information security threats are becoming more advanced, intelligent, and diverse. Even though the awareness of the importance of information security increases, the information security budget is not enough because of the lack of effectiveness measurement of the information security investment. Therefore, it is necessary to optimize the information security investment in each business environment to minimize the cost of operating the information security countermeasures and mitigate the damages occurred from the information security breaches. In this paper, using genetic algorithms we propose an investment optimization model for information security countermeasures with the limited budget. The optimal information security countermeasures were derived based on the actual information security investment status of SMEs. The optimal solution supports the decision on the appropriate investment level for each information security countermeasures.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.5
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• pp.26-35
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• 2003

Propellers operating in a given nonuniform ship wake generate unsteady loads leading to undesirable stern vibration problems. The skew is known to be the most proper and effective geometric parameter to control or reduce the fluctuating forces on the shaft. This paper assumes the skew profile as either a quadratic or a cubic function of the radius and determines the coefficients of the polynomial function by applying the simplex method. The method uses the converted unconstrained algorithm to solve the constrained minimization problem of 6-component shaft excitation forces. The propeller excitation was computed either by applying the two-dimensional gust theory for quick estimation or by the fully three-dimensional unsteady lifting surface theory in time domain for an accurate solution. A sample result demonstrates that the shaft forces can be further reduced through optimization from the original design.

• Journal of Korean Society for Quality Management
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• v.40 no.1
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• pp.88-91
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• 2012

Joint optimization of preventive age replacement and inventory policy is considered in this paper. There are three decision variables in the problem: (i) preventive replacement age of the operating unit, (ii) order quantity per order and (iii) reorder point for spare replenishment. Preventive replacement age and order quantity are jointly determined so as to minimize the expected cost rate, and then the reorder point for meeting a desired service level is found. A numerical example is included to explain the joint optimization model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.11
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• pp.1051-1058
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• 2011

The military communication equipment is required the high reliability for operating adequate functions under severe conditions. This reliability is the essential element for the quality of the product, for the uncontrolled factors, such as the clearance, damage of the material, the reduction of stiffness, which are the designer is unable to handle. In this paper, the uncertainty for the dimension was supposed to the probability model for the military communication equipment, and the average of the objective function was minimized for reducing design uncertainty. The reliability-based design optimization which was implemented the limit state function was formulated into the mathematical model, so the reliable optimized structure was implemented than the base-line design.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1873-1881
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• 2014

This paper deals with the design of multi-machine power system stabilizers (PSSs) and Static var compensator (SVC) using Modified shuffled frog leaping algorithm (MSFLA). The effectiveness of the proposed scheme for optimal setting of the PSSs and SVC controllers has been attended. The PSSs and SVC controllers designing is converted to an optimization problem in which the speed deviations between generators are involved. In order to compare the capability of PSS and SVC, they are designed independently once, and in a coordinated mode once again. The proposed method is applied on a multi-machine power system under different operating conditions and disturbances to confirm the effectiveness of it. The results of tuned PSS controller based on MSFLA (MSFLAPSS) and tuned SVC controller based on MSFLA (MSFLA SVC) are compared with the Strength pareto evolutionary algorithm (SPEA) and Particle swarm optimization (PSO) based optimized PSS and SVC through some performance to reveal its strong performance.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.2
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• pp.90-98
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• 2013

The k-out-of-n system with mixed redundancy is defined as k-out-of-n system which both includes warm-standby and cold-standby components. In case that operating components in the system fail and the system needs quick transition of standby components to operation state, the k-out-of-n system with mixed redundancy is useful for decreasing system failure rate and operational cost. Reliability-Redundancy Optimization Problem (RROP) involves selection of components with multiple choices and redundancy levels for maximizing system reliability with constraints such as cost, weight, etc. A solution methodology by using harmony search algorithm for RROP of the k-out-of-n system with mixed redundancy to maximize system reliability was suggested in this study.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.58-63
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• 2012

The Test Signal Method is adopted to analyze the impact of thyristor controlled series capacitor (TCSC) on sub-synchronous oscillation. The results show that the simulation system takes the risk of Sub-synchronous Oscillation (SSO) while the TCSC is operating in the capacitive region. A supplementary excitation damping controller (SEDC) is used to mitigate SSO caused by the TCSC. A new optimization method which is aimed for optimal phase compensation is proposed. This method is realized by using the particle swarm optimization (PSO) algorithm. The simulation results show that the SEDC designed by this method has superior suitability, and that the secure operation scope of the TCSC is greatly increased.