• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3665-3674
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• 2021

One of the important parts of the in-core fuel management is loading pattern optimization (LPO). The loading pattern optimization as a reasonable design of the in-core fuel management can improve both economic and safe aspects of the nuclear reactor. This work proposes the hybrid of fuzzy logic controller with harmony search algorithm (HS) for loading pattern optimization in a pressurized water reactor. The music improvisation process to find a pleasing harmony is inspiring the harmony search algorithm. In this work, the adjustment of the harmony search algorithm parameters such as the bandwidth and the pitch adjustment rate are increasing performance of the proposed algorithm which is done through a fuzzy logic controller. Hence, membership functions and fuzzy rules are designed to improve the performance of the HS algorithm and achieve optimal results. The objective of the method is finding an optimum core arrangement according to safety and economic aspects such as reduction of power peaking factor (PPF) and increase of effective multiplication factor (Keff). The proposed approach effectiveness has been tried in two cases, Michalewicz's bivariate function problem and NEACRP LWR core. The results show that by using fuzzy harmony search algorithm the value of the fitness function is improved by 15.35%. Finally, with regard to the new solutions proposed in this research it could be used as a trustworthy method for other optimization issues of engineering field.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.3
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• pp.409-428
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• 1995

Job shop scheduling with m different machines and n different jobs is a NP-hard problem of combinatorial optimization. The purpose of the paper is to develop the heuristic method using tabu search for job shop scheduling to minimize makespan or mean flowtime. To apply tabu search to job shop scheduling problem, in this paper we propose the several move methods that employ insert moves in order to generate the neighbor solutions, and present the efficient rescheduling procedure that yields active schedule for a changed operation sequence by a move of operations. We also discuss the tabu search techniques of diversifying the search of solution space as well as the simple tabu search. By experiments, we find the appropriate tabu list size and tabu attributes, and analyze the proposed tabu search techniques with respect to the quality of solutions and the efforts of computation. The experimental results show that the proposed tabu search techniques using long-term memory function have the ability to search a good solution, and are more efficient in the mean flowtime minimization problem than in the makespan minimization.

• Journal of computational fluids engineering
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• v.17 no.4
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• pp.32-40
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• 2012

Efficient Global Optimization (EGO) method is a global optimization technique which can select the next sample point automatically by infill sampling criteria (ISC) and search for the global minimum with less samples than what the conventional global optimization method needs. ISC function consists of the predictor and mean square error (MSE) provided from the kriging model which is a stochastic metamodel. Also the constrained EGO method can minimize the objective function dealing with the constraints under EGO concept. In this study the constrained EGO method applied to the RAE2822 airfoil shape design formulated with the constraint. But the noisy CFD data caused the kriging model to fail to depict the true function. The distorted kriging model would make the EGO deviate from the correct search. This distortion of kriging model can be handled with the interpolation(p=free) kriging model. With the interpolation(p=free) kriging model, however, the search of EGO solution was stalled in the narrow feasible region without the chance to update the objective and constraint functions. Then the accuracy of EGO solution was not good enough. So the three-step search method was proposed to obtain the accurate global minimum as well as prevent from the distortion of kriging model for the noisy constrained CFD problem.

• Journal of the Korean Society for information Management
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• v.29 no.1
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• pp.175-190
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• 2012

This study aims to investigate the current status of mobile search functions of Korean search portals, namely Google Korea, Naver, Nate, Daum, and Yahoo Korea. This study focuses on unique mobile search functionalities, such as voice search, music search, code search, and visual/ object search. In particular, this study analyzed characteristics of these search functions and evaluated their performances based on the accuracy and the speed of recognition. The results of this study show that both Naver and Daum support various mobile searching functions, whereas Google only supports voice search. Nate and Yahoo do not offer any unique function. The results of this study can be applied to the portal's effective development of mobile search functionalities.

• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.39-42
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• 2000

Motion estimation plays an important role for video coding. In this paper, we derive optimal search patterns for fast block matching motion estimation. By analyzing the block matching algorithm as a function of block shape and size, we can find an optimal search pattern for initial motion estimation. The proposed idea, which has been verified experimentally by computer simulations, can provide an analytical basis for the current MPEG-2 proposals. In order to choose a more compact search pattern for BMA, we exploit the statistical relationship between the motion and the frame difference of each block.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.443-449
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• 2017

Swarm of low-cost UAVs for search mission has benefit in the sense of rapid search compared to use of single high-end UAV. As the number of UAVs forming swarm increases, not only the time for the mission planning increases, but also the system to operate UAVs has excessive burden. This paper addresses a decentralized area search algorithm adequate for multiple UAVs which takes advantages of flexibility, robustness, and simplicity. To down the cost, it is assumed that each UAV has limited ability: close-communication, basic calculation, and limited memory. In close-communication, heath conditions and search information are shared. And collision avoidance and consensus of next search direction are then done. To increase weight on un-searched area and to provide overlapped search, the score function is introduced. Performance and operational characteristics of the proposed search algorithm and mission planning logic are verified via numerical simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.71-79
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• 2006

Address lookup is an essential function in the Internet routers, and it determines overall router performance. In this paper, we have thoroughly investigated the binary-search-based address lookup algorithms and proposed a new algorithm based on binary search on prefix lengths. Most of the existing binary search schemes perform binary search on prefix values, and hence the lookup speed is proportional to the length of prefixes or the log function of the number of prefixes. The previous algorithm based on binary search on prefix lengths has superior lookup performance than others. However, the algorithm requires very complicated pre-computation of markers and best matching prefixes in internal nodes since naive binary search is not possible in their scheme. This complicated pre-computation makes the composition of the routing table and incremental update very difficult. By using leaf-pushing, the proposed algorithm in this paper removes the complicated pre-computation of the Previous work in performing the binary search on prefix lengths. The performance evaluation results show that the proposed scheme has very good performance in lookup speed compared with previous works.

• The Korean Journal of Archival Studies
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• no.37
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• pp.273-305
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• 2013

In order to actively use of records and information in current digital record management systems, we have to check whether a system is designed to fully support the user of records and whether the good use of the system is being. This study analyzed the status of the use of the search function of Records Management System(RMS) for public agencies, and evaluated them. In order to investigate the status of the use of the search function, it surveyed records managers of public agencies using the RMS. The result showed that records managers unsatisfied with the usability and the search performance of the RMS. To evaluate the search function, it identified the functional requirement of the system and develops a checklist that can be used for evaluation. Two assessments were conducted. Firstly, as pre-evaluation, it assessed the degree of implementation of the current RMS according to the checklist as an inspection chart using document examination method. Secondly, it assessed the degree of implementation using a survey of records managers of public agencies that use the RMS. Assessment results show the improvement of the basic features that are essential to the system is required. In particular, the search function is required to improve user-friendliness for the user. For the advance of RMS, this study discusses the necessity for improvement of the search functions, the build of continuous maintenance and management system, and the user education.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.3
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• pp.103-112
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• 1998

In this study, database schema which is capable of maintaining various design-knowledge and applicable to the structural designs has been presented. Futhermore, by utilizing the database system, RECODSS (REinforced COncrete Design Support System) was developed as well. Knowledge-base that were formulated from the document is constructed by applying the concrete standard specifications of Korea from 1989. The basic drawing was prepared by $AutoCAD^TM$. As an inference in the preliminary design, the certainty function and the interpolation function were presented. The certainty function is made by assuming linear relations between each data while referencing $MYCIN^TM$ (expert systems). Nevertheless, the interpolation function was made by utilizing the linear Lagrange interpolation. For the search of the design-knowledge, fast search algorithm and full-text search algorithm were used, however, the design engine was programmed with C language. RECODSS was applied for designing a slab and a beam member. And the results were compared with the existing results. In conclusion, RECODSS was able to efficiently manage various design knowledge and to introduce stable design results.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.3
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• pp.284-289
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• 2005

A structural design system is developed for the optimum design of double hull tankers based on the multi-objective function method. As a multi-objective function method, Pareto optimal based random search method is adopted to find the minimum structural weight and fabrication cost. The fabrication cost model is developed by considering the welding technique, welding poses and assembly stages to manage the fabrication man-hour and process. In this study, a new structural design is investigated due to the rapidly increased material cost. Several optimum structural designs on the basis of high material cost are carried out based on the Pareto optimal set obtained by the random search method. The design results are compared with existing ship, which is designed under low material cost.