• Title/Summary/Keyword: Heuristic Function

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Gray Wolf Optimizer for the Optimal Coordination of Directional Overcurrent Relay

  • Kim, Chang-Hwan;Khurshaid, Tahir;Wadood, Abdul;Farkoush, Saeid Gholami;Rhee, Sang-Bong
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1043-1051
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    • 2018
  • The coordination of directional overcurrent relay (DOCR) is employed in this work, considering gray wolf optimizer (GWO), a recently designed optimizer that employs the hunting and leadership attitude of gray wolves for searching a global optimum. In power system protection coordination problem, the objective function to be optimized is the sum of operating time of all the main relays. The coordination of directional overcurrent relays is formulated as a linear programming problem. The proposed optimization technique aims to minimize the time dial settings (TDS) of the relays. The calculation of the Time Dial Setting (TDS) setting of the relays is the core of the coordination study. In this article two case studies of IEEE 6-bus system and IEEE 30-bus system are utilized to see the efficiency of this algorithm and the results had been compared with the other algorithms available in the reference and it was observed that the proposed scheme is quite competent for dealing with such problems. From analyzing the obtained results, it has been found that the GWO approach provides the most globally optimum solution at a faster convergence speed. GWO has achieved a lot of relaxation due to its easy implementation, modesty and robustness. MATLAB computer programming has been applied to see the effectiveness of this algorithm.

Fuzzy-MOEH : Resource Constraints Project Scheduling Algorithm with Fuzzy Concept (Fuzzy-MOEH : 퍼지 개념을 이용한 자원제약 프로젝트 스케줄링 알고리즘)

  • Koh, Jang-Kwon;Shin, Ye-Ho;Ryu, Keun-Ho;Kim, Hong-Gi
    • Journal of KIISE:Computing Practices and Letters
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    • v.7 no.4
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    • pp.359-371
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    • 2001
  • Project scheduling under resource constraint conditions have contained to many uncertain factors and it is perfonned by human experts. The expert identifies the activities of the project, decides the precedent relationships between these activities, and then construct the schedule using expected activity's duration. At this time, most of the scheduling methods concentrate on one of scheduling factor between activity duration and cost. And the activity duration, which is the most important factor in scheduling, is decided by heuristic of expert. Therefore it may cause uncertainty of activity duration decision and the use of this activity duration may increase the uncertainty of constructed schedule. This paper proposes Fuzzy-MOEH scheduling algorithm, which is the aggregation of the fuzzy number for deciding activity duration and applies the cost function for solving the problems of previous scheduling methods. This paper also analyze the utility and property of Fuzzy-MEOH algorithm through the comparison between Fuzzy-MEOH algorithm and existing MEOH algorithm.

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A Study on the Optimization Model for the Project Portfolio Manpower Assignment Using Genetic Algorithm (유전자 알고리즘을 이용한 프로젝트 포트폴리오 투입인력 최적화 모델에 관한 연구)

  • Kim, Dong-Wook;Lee, Won-Young
    • Journal of Information Technology Services
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    • v.17 no.4
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    • pp.101-117
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    • 2018
  • Companies are responding appropriately to the rapidly changing business environment and striving to lead those changes. As part of that, we are meeting our strategic goals through IT projects, which increase the number of simultaneous projects and the importance of project portfolio management for successful project execution. It also strives for efficient deployment of human resources that have the greatest impact on project portfolio management. In the early stages of project portfolio management, it is very important to establish a reasonable manpower plan and allocate performance personnel. This problem is a problem that can not be solved by linear programming because it is calculated through the standard deviation of the input ratio of professional manpower considering the uniformity of load allocated to the input development manpower and the importance of each project. In this study, genetic algorithm, one of the heuristic methods, was applied to solve this problem. As the objective function, we used the proper input ratio of projects, the input rate of specialist manpower for important projects, and the equal load of workload by manpower. Constraints were not able to input duplicate manpower, Was used as a condition. We also developed a program for efficient application of genetic algorithms and confirmed the execution results. In addition, the parameters of the genetic algorithm were variously changed and repeated test results were selected through the independent sample t test to select optimal parameters, and the improvement effect of about 31.2% was confirmed.

The flexible routing with flex for the fast delivery

  • Park, TaeJoon;Chung, Yerim
    • Journal of the Korea Society of Computer and Information
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    • v.26 no.9
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    • pp.143-153
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    • 2021
  • In this paper, we propose "flexible routing with flex" to provide fast delivery by using the flexible routing for the delivery vehicle and crowd-shipper named flex. To this end, we have introduced an algorithm that can build the delivery plan for delivery vehicles and flexes. The introduced algorithm uses the 2-opt algorithm to construct routes with low complexity and acceptable quality, and the revised saving algorithm to assign customer orders to the flex. The algorithm allows the vehicle and the flex to function complement each other without separating the delivery vehicle from the flex. The experiments consider the 3 different instances named Random, Mixed, Cluster, and show that "the flexible routing with flex" has a better result than "vehicle only". The sensitivity analysis of the flex cost and time penalty shows "the flexible routing with flex" can provide better service not only to the customers who are serviced by flex but also to the customers who are serviced by the delivery vehicle.

Scheduling of Printing Process in which Ink Color Changes Exist (잉크 색상 변화가 존재하는 인쇄 공정의 스케줄링)

  • Moon, Jae Kyeong;Uhm, Hyun Seop;Tae, Hyun Chul
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.44 no.4
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    • pp.32-42
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    • 2021
  • The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

Short-term Scheduling Optimization for Subassembly Line in Ship Production Using Simulated Annealing (시뮬레이티드 어닐링을 활용한 조선 소조립 라인 소일정계획 최적화)

  • Hwang, In-Hyuck;Noh, Jac-Kyou;Lee, Kwang-Kook;Shin, Jon-Gye
    • Journal of the Korea Society for Simulation
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    • v.19 no.1
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    • pp.73-82
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    • 2010
  • Productivity improvement is considered as one of hot potato topics in international shipyards by the increasing amount of orders. In order to improve productivity of lines, shipbuilders have been researching and developing new work method, process automation, advanced planning and scheduling and so on. An optimization approach was accomplished on short-term scheduling of subassembly lines in this research. The problem of subassembly line scheduling turned out to be a non-deterministic polynomial time problem with regard to SKID pattern’s sequence and worker assignment to each station. The problem was applied by simulated annealing algorithm, one of meta-heuristic methods. The algorithm was aimed to avoid local minimum value by changing results with probability function. The optimization result was compared with discrete-event simulation's to propose what pros and cons were. This paper will help planners work on scheduling and decision-making to complete their task by evaluation.

A Study on Design Guideline of Cyber Chatting System based on Usability Evaluation (사이버 채팅 시스템의 사용성 평가를 통한 사용자 인터페이스 설계 지침에 관한 연구)

  • 전대인;박정순
    • Archives of design research
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    • v.14 no.1
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    • pp.35-46
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    • 2001
  • Recently varieties of user groups are formed as the number of people using cyber chatting gets increased and there are many changes in the range and field of its use. But because most of the cyber chatting systems are being operated to enlarge the additional sonics use, the using environments are stereotyped. And as its function is being various as well, it can not provide with a user-centered environment. So this thesis compares and analyzes the problems derived from the usability evaluation for solving the problems in using cyber chatting systems, and presents the guidelines of emotion-intended user interface design for improving the usability as the result of the analysis. First, this study investigates cyber chatting systems as a means of web communication tools through the existing literatures. Secondly, this study finds out the problems in using them through satisfaction evaluation, heuristic evaluation, performance evaluation, and observation evaluation and presents a way of solving the provisional problems in using them as the analysis of the result of usability evaluation. And this was proceeded for the purpose of applying and activating the better usability evaluation of cyber chatting systems later. Through the usability evaluation, it is found out that the structuralization of chatting function, the screen visibility by the size and arrangement of the compositional elements of a screen, and the improvement and development of the proper metaphor use of images and functions by the communication environment are necessary.

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Development of Intelligent ATP System Using Genetic Algorithm (유전 알고리듬을 적용한 지능형 ATP 시스템 개발)

  • Kim, Tai-Young
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.131-145
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    • 2010
  • The framework for making a coordinated decision for large-scale facilities has become an important issue in supply chain(SC) management research. The competitive business environment requires companies to continuously search for the ways to achieve high efficiency and lower operational costs. In the areas of production/distribution planning, many researchers and practitioners have developedand evaluated the deterministic models to coordinate important and interrelated logistic decisions such as capacity management, inventory allocation, and vehicle routing. They initially have investigated the various process of SC separately and later become more interested in such problems encompassing the whole SC system. The accurate quotation of ATP(Available-To-Promise) plays a very important role in enhancing customer satisfaction and fill rate maximization. The complexity for intelligent manufacturing system, which includes all the linkages among procurement, production, and distribution, makes the accurate quotation of ATP be a quite difficult job. In addition to, many researchers assumed ATP model with integer time. However, in industry practices, integer times are very rare and the model developed using integer times is therefore approximating the real system. Various alternative models for an ATP system with time lags have been developed and evaluated. In most cases, these models have assumed that the time lags are integer multiples of a unit time grid. However, integer time lags are very rare in practices, and therefore models developed using integer time lags only approximate real systems. The differences occurring by this approximation frequently result in significant accuracy degradations. To introduce the ATP model with time lags, we first introduce the dynamic production function. Hackman and Leachman's dynamic production function in initiated research directly related to the topic of this paper. They propose a modeling framework for a system with non-integer time lags and show how to apply the framework to a variety of systems including continues time series, manufacturing resource planning and critical path method. Their formulation requires no additional variables or constraints and is capable of representing real world systems more accurately. Previously, to cope with non-integer time lags, they usually model a concerned system either by rounding lags to the nearest integers or by subdividing the time grid to make the lags become integer multiples of the grid. But each approach has a critical weakness: the first approach underestimates, potentially leading to infeasibilities or overestimates lead times, potentially resulting in excessive work-inprocesses. The second approach drastically inflates the problem size. We consider an optimized ATP system with non-integer time lag in supply chain management. We focus on a worldwide headquarter, distribution centers, and manufacturing facilities are globally networked. We develop a mixed integer programming(MIP) model for ATP process, which has the definition of required data flow. The illustrative ATP module shows the proposed system is largely affected inSCM. The system we are concerned is composed of a multiple production facility with multiple products, multiple distribution centers and multiple customers. For the system, we consider an ATP scheduling and capacity allocationproblem. In this study, we proposed the model for the ATP system in SCM using the dynamic production function considering the non-integer time lags. The model is developed under the framework suitable for the non-integer lags and, therefore, is more accurate than the models we usually encounter. We developed intelligent ATP System for this model using genetic algorithm. We focus on a capacitated production planning and capacity allocation problem, develop a mixed integer programming model, and propose an efficient heuristic procedure using an evolutionary system to solve it efficiently. This method makes it possible for the population to reach the approximate solution easily. Moreover, we designed and utilized a representation scheme that allows the proposed models to represent real variables. The proposed regeneration procedures, which evaluate each infeasible chromosome, makes the solutions converge to the optimum quickly.

Optimized Mix Proportioning of Steel and Hybrid Reinforced Concrete Using Harmony Search Algorithm (화음탐색법을 이용한 강섬유 및 하이브리드 섬유보강 콘크리트의 최적배합 설계)

  • Lee, Chi-Hoon;Lee, Joo-Ha;Yoon, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.18 no.2 s.92
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    • pp.151-159
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    • 2006
  • The guide line of the SFRC mix design was not established, and the convenience of the practical application on the spot is not so good. In this paper, hence, the program which is optimized to result the mix proportion by the flexural strength and toughness, was developed to apply to SFRC on the practical spot. This program could minimize the number of trial mixes and get an economical and appropriate mixture. In addition, the theoretical background on which the program is based, will be the basis of the embodied method to mixing SFRC. Additionally, new algorithm, in this paper, was used to develop the mix proportioning program of SFRC. The new algorithm is the Harmony Search which is the heuristic method mimicking the improvisation of music players, Musical performances seek a best state determined by aesthetic estimation, as the optimization algorithms seek a best state determined by objected function value. And, it was developed the program about single fiber reinforced concrete, beside to the hybrid fiber reinforced concrete that two kinds of steel fibers, which have the different geometry, was reinforced. This will be able to keep the world trend to study, hence, offers the basis of the next research about hybrid fiber reinforced concrete.

A Multiobjective Genetic Algorithm for Static Scheduling of Real-time Tasks (다목적 유전 알고리즘을 이용한 실시간 태스크의 정적 스케줄링 기법)

  • 오재원;김희천;우치수
    • Journal of KIISE:Software and Applications
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    • v.31 no.3
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    • pp.293-307
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    • 2004
  • We consider the problem of scheduling tasks of a precedence constrained task graph, where each task has its execution time and deadline, onto a set of identical processors in a way that simultaneously minimizes the number of processors required and the total tardiness of tasks. Most existing approaches tend to focus on the minimization of the total tardiness of tasks. In another methods, solutions to this problem are usually computed by combining the two objectives into a simple criterion to be optimized. In this paper, the minimization is carried out using a multiobjective genetic algorithm (GA) that independently considers both criteria by using a vector-valued cost function. We present various GA components that are well suited to the problem of task scheduling, such as a non-trivial encoding strategy. a domination-based selection operator, and a heuristic crossover operator We also provide three local improvement heuristics that facilitate the fast convergence of GA's. The experimental results showed that when compared to five methods used previously, such as list-scheduling algorithms and a specific genetic algorithm, the Performance of our algorithm was comparable or better for 178 out of 180 randomly generated task graphs.