• Smart Structures and Systems
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• v.21 no.3
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• pp.263-278
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• 2018

Thermal Exchange Optimization (TEO) is a newly developed algorithm which mimics the thermal exchange between a solid object and its surrounding fluid. In this paper, an improved version of the TEO is developed to fix the shortcomings of the standard version. To demonstrate the viability of the new algorithm, the CEC 2016's single objective problems are considered along with the discrete size optimization of benchmark skeletal structures. Problem specific constraints are handled using a fly-back mechanism. The results show the validity of the improved TEO method compared to its standard version and a number of well-known algorithms.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1234-1239
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• 2003

In the product design process computer-aided engineering and optimization tools are widely utilized in order to reduce the total development time and cost. Since several simulation tools are involved in the process, information losses, omissions, or errors are common and the importance of seamless information exchange among the tools has been increased. In this study ISO STEP standards are adopted to represent the neutral format for CAE/CAO information exchange. The schema of AP209 is used to define the information of finite element analysis and the new schema is proposed to describe the information of structural optimization based on the STEP methodology. The schema is implemented by EXPRESS, information modeling language, and ST-Developer is employed to generate C++ classes and STEP Rose Library by using the schema denoted. To substantiate the proposed approach, the information access interfaces of the finite element modeling software (FEMAP), structural optimization software (GENESIS) and in-house topology optimization program are developed. Examples of the size optimization of a three-bar truss and topology optimization of a MBB beam are shown to validate the information exchange of finite element analysis and structural optimization using STEP standards.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1301-1318
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• 2017

In order to utilize the licensed channel of cognitive radio (CR) when the primary user (PU) is detected busy, a benefit-exchange access mode based on cooperative communication is proposed to allow secondary user (SU) to access the busy channel through giving assistance to PU's communication in exchange for some transmission bandwidth. A holistic joint optimization problem is formulated to maximize the total throughput of CR system through jointly optimizing the parameters of cooperative spectrum sensing (CSS), including the local sensing time, the pre-configured sensing decision threshold, the forward power of cooperative communication, and the bandwidth and transmission power allocated to SUs in benefit-exchange access mode and traditional access mode, respectively. To solve this complex problem, a combination of bi-level optimization, interior-point optimization and exhaustive optimization is proposed. Simulation results show that, compared with the tradition throughput maximizing model (TTMM), the proposed holistic joint optimization model (HJOM) can make use of the channel effectively even if PU is busy, and the total throughput of CR obtains a considerable improvement by HJOM.

• Korean Journal of Computational Design and Engineering
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• v.12 no.1
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• pp.8-14
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• 2007

In the product design process computer-aided engineering and optimization tolls are widely utilized in order to reduce the total development time and cost. Since several simulation tools are involved in the process, information losses, omissions, or errors are common and the importance of seamless information exchange among the tools has been increased. In this work, ISO STEP standards are adopted to represent the neutral format for structural analysis and optimization. The schema of AP209 defined the information of finite element analysis is used and the new schema is proposed to describe the information of structural optimization based on the STEP methodology. The schema is implemented by EXPRESS, information modeling language, and ST-Developer is employed to generate C++ classes and STEP Rose Library by using the schema denoted. To substantiate the proposed approach, the information access interfaces of the finite element modeling software (FEMAP), structural optimization software(GENESIS) and in-house topology optimization program are developed. Examples are shown to validate the information exchange of finite element analysis and structural optimization using STEP standards.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.174-181
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• 2004

Recently, many studies have been undergoing to reduce working time in field of machine tool. There are two ways of reducing working time to reduce actual working time by heighten spindle speed and to reduce stand-by time by shortening tool exchange time. Auto tool changer belongs to latter case. Fixed address type auto tool changer can store more number of tools in small space than magazine transfer Ope and can shorten tool exchange time. This study focuses on the topology optimization to reduce the weight of the fixed address type ATC. The optimization program using a real number coding genetic algorithm is developed and is applied to the 10-bar truss optimization problem to verify the developed program. And, it is shown that the developed program gives better results than other methods. Finally, The developed program applied to optimize the fixed address type ATC.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.179-186
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• 2005

This paper describes a genetic algorithm and compares three crossover operators for Rural Postman Problem with Time Windows (RPPTW). The RPPTW which is a multiobjective optimization problem, is an extension of Rural Postman Problem(RPP) in which some service places (located at edge) require service time windows that consist of earliest time and latest time. Hence, RPM is a m띤tieect optimization Problem that has minimal routing cost being serviced within the given time at each service Place. To solve the RPPTW which is a multiobjective optimization problem, we obtain a Pareto-optimal set that the superiority of each objective can not be compared. This Paper performs experiments using three crossovers for 12 randomly generated test problems and compares the results. The crossovers using in this Paper are Partially Matched Exchange(PMX) Order Exchange(OX), and Modified Order Exchange(MOX) which is proposed in this paper. For each test problem, the results show the efficacy of MOX method for RPPTW.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.67-72
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• 2004

Many port states such as New Zealand, the USA, Australia and Canada have strict regulations to prevent ships which arrive in their port from discharging polluted ballast water which contain harmful aquatic organism and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, they perceived that the ballast exchange in deep sea is the most effective method, together with submitting the ballast management plan which contains the effective exchange method, ballast system and safety consideration. In this study, we pursued both nautical engineering analysis and optimization of algorithm in order to generate the sequence of stability and rapidity. Heuristic Algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm, for automatic exchange of ballast water, by redefining core elements of the $A^\ast$ algorithm, such as node, operator and evaluation function. Final version of the optimized algorithm has been applied to existing bulk carrier and the performance of the algorithm has been verified successfully.

• Journal of Ocean Engineering and Technology
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• v.18 no.4 s.59
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• pp.65-70
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• 2004

Many port states, such as New Zealand, U.S.A., Australia, and Canada, have strict regulations to prevent arriving ships from discharging polluted ballast water that contains harmful aquatic organisms and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, ballast exchange in deep sea is perceived as the most effective method of emptying ballast water. The ballast management plan contains the effective exchange method, ballast system, and safety considerations. In this study, we pursued both nautical engineering analysis and optimization of the algorithm, in order to generate the sequence of stability and rapidity. A heuristic algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm for the automatic exchange of ballast water, by redefining core elements of the A$\ast$ algorithm, such as node, operator, and evaluation function. The final version of the optimized algorithm has been applied to existing bulk carrier, and the performance of the algorithm has been successfully verified.

• IE interfaces
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• v.24 no.4
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• pp.379-386
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• 2011

The importance of renewable energy technology is discussed and next generation power transmission networks, which is called the smart grid, are constructed in developed countries. However for construction and operation of the smart grid, it is required not only to develop the electrical power generation technologies and transmission equipments but also to study systematic analysis and optimization for design and operation of the smart grid. In this paper we study electrical power trade in the smart grid using operations research models and simulation methods. We also consider future electrical power exchange markets in Korea and build four scenarios and the related optimization and simulation models, which reflect electrical power transaction pricing strategies of stake-holders. We can also simulate electrical power exchange market and analyze the results of electrical power trading, which can give us some insights for future electrical power exchange market.

• KIEE International Transactions on Power Engineering
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• v.5A no.3
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• pp.303-308
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• 2005

The restructure of the electrical power industry is accompanied by the extension of the electrical power exchange. One of the key pieces of information used to determine how much power can be transferred through the network is known as available transfer capability (ATC). The traditional ATC deterministic approach is based on the severest case and it involves a complex procedure. Therefore, a novel approach for A TC calculation is proposed using cost optimization in this paper. The Jeju Island interconnected HVDC system has inland KEPCO (Korean Electric Power Corporation) systems, and its demand is increasing at the rate of about $\10[%]$ annually. To supply this increasing demand, the capability of the HVDC system must be enlarged. This paper proposes the optimal transfer capability of the HVDC system between Haenam in the inland and Jeju in Cheju Island through cost optimization. The cost optimization is based on generating cost in Jeju Island, transfer cost through Jeju-Haenam HVDC system and outage cost with one depth (N-1 contingency).