• Title/Summary/Keyword: Multi-strategy

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Evaluating the Application of Portable Safety Equipment in Nuclear Power Plants using Multi-unit PSA (다수기 PSA 기반 원자력 발전소 이동형 안전 설비 활용성 평가)

  • Jae Young Yoon;Ho-Gon Lim;Jong Woo Park
    • Journal of the Korean Society of Safety
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    • v.38 no.3
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    • pp.110-120
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    • 2023
  • Following the Fukushima accident, portable equipment employed as accident mitigating systems have been installed and operated to reduce core damage and large early release frequencies. In addition, the establishment of an accident management strategy has gained importance. This study investigated the current status of portable equipment including the international portable equipment FLEX (diverse and flexible coping strategies), and domestic portable equipment multi-barrier accident coping strategy (MACST). Research on optimal utilization of MACST remains insufficient. As a preliminary study for establishing an optimal strategy, sensitivity studies were conducted to facilitate the priority of use on portable equipment, number of portable equipment, and dependency of operator actions based on a multi-unit probabilistic safety assessment model. The results revealed the conditions that reduced the multi-unit and site conditional core damage probabilities, indicating the optimal strategy of MACST. The results of this study can be used as a reference for establishing an optimal strategy that utilizes domestic safety equipment in the future.

An Offloading Strategy for Multi-User Energy Consumption Optimization in Multi-MEC Scene

  • Li, Zhi;Zhu, Qi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.10
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    • pp.4025-4041
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    • 2020
  • Mobile edge computing (MEC) is capable of providing services to smart devices nearby through radio access networks and thus improving service experience of users. In this paper, an offloading strategy for the joint optimization of computing and communication resources in multi-user and multi-MEC overlapping scene was proposed. In addition, under the condition that wireless transmission resources and MEC computing resources were limited and task completion delay was within the maximum tolerance time, the optimization problem of minimizing energy consumption of all users was created, which was then further divided into two subproblems, i.e. offloading strategy and resource allocation. These two subproblems were then solved by the game theory and Lagrangian function to obtain the optimal task offloading strategy and resource allocation plan, and the Nash equilibrium of user offloading strategy games and convex optimization of resource allocation were proved. The simulation results showed that the proposed algorithm could effectively reduce the energy consumption of users.

A Multi-Agent Simulation for the Electricity Spot Market

  • Oh, Hyungna
    • Proceedings of the Korea Inteligent Information System Society Conference
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    • 2003.05a
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    • pp.255-263
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    • 2003
  • A multi-agent system designed to represent newly deregulated electricity markets in the USA is aimed at testing the capability of the multi-agent model to replicate the observed price behavior in the wholesale market and developing a smart business intelligence which quickly searches the optimum offer strategy responding to the change in market environments. Simulation results show that the optimum offer strategy is to withhold expensive generating units and submit relatively low offers when demand is low, regardless of firm size; the optimum offer strategy during a period of high demand is either to withhold capacity or speculate for a large firm, while it is to be a price taker a small firm: all in all, the offer pattern observed in the market is close to the optimum strategy. From the firm's perspective, the demand-side participation as well as the intense competition dramatically reduces the chance of high excess profit.

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Development of Pareto strategy multi-objective function method for the optimum design of ship structures

  • Na, Seung-Soo;Karr, Dale G.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.6
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    • pp.602-614
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    • 2016
  • It is necessary to develop an efficient optimization technique to perform optimum designs which have given design spaces, discrete design values and several design goals. As optimization techniques, direct search method and stochastic search method are widely used in designing of ship structures. The merit of the direct search method is to search the optimum points rapidly by considering the search direction, step size and convergence limit. And the merit of the stochastic search method is to obtain the global optimum points well by spreading points randomly entire the design spaces. In this paper, Pareto Strategy (PS) multi-objective function method is developed by considering the search direction based on Pareto optimal points, the step size, the convergence limit and the random number generation. The success points between just before and current Pareto optimal points are considered. PS method can also apply to the single objective function problems, and can consider the discrete design variables such as plate thickness, longitudinal space, web height and web space. The optimum design results are compared with existing Random Search (RS) multi-objective function method and Evolutionary Strategy (ES) multi-objective function method by performing the optimum designs of double bottom structure and double hull tanker which have discrete design values. Its superiority and effectiveness are shown by comparing the optimum results with those of RS method and ES method.

A Multi-Class Task Scheduling Strategy for Heterogeneous Distributed Computing Systems

  • El-Zoghdy, S.F.;Ghoneim, Ahmed
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.1
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    • pp.117-135
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    • 2016
  • Performance enhancement is one of the most important issues in high performance distributed computing systems. In such computing systems, online users submit their jobs anytime and anywhere to a set of dynamic resources. Jobs arrival and processes execution times are stochastic. The performance of a distributed computing system can be improved by using an effective load balancing strategy to redistribute the user tasks among computing resources for efficient utilization. This paper presents a multi-class load balancing strategy that balances different classes of user tasks on multiple heterogeneous computing nodes to minimize the per-class mean response time. For a wide range of system parameters, the performance of the proposed multi-class load balancing strategy is compared with that of the random distribution load balancing, and uniform distribution load balancing strategies using simulation. The results show that, the proposed strategy outperforms the other two studied strategies in terms of average task response time, and average computing nodes utilization.

Multi-dimensional Limiting Strategy for Robust, Accurate and Efficient Computations of Compressible Flows on Unstructured Meshes

  • Park, Jin-Seok;Yoon, Sung-Hwan;Kim, Chon-Gam
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.378-385
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    • 2008
  • The present paper deals with the accurate and robust limiting procedure for the multi-dimensional flow analysis on unstructured meshes. The multi-dimensional limiting process (MLP) which was successfully proposed on structured grid system is extended to unstructured meshes. Based on MUSCL-type framework on unstructured meshes, the new slope limiter is devised to satisfy the MLP condition, which is quite effective to regulate the unwanted oscillations, especially on multiple dimensions. Considering the neighborhood based on the vertex of the cell, as well as the edge, this limiting strategy captures the multi-dimensional flow features very accurately with the proper stencils. From the various numerical results, these desirable characteristics of the proposed limiting strategy are clearly shown.

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Multi-dimensional Limiting Strategy for Robust, Accurate and Efficient Computations of Compressible Flows on Unstructured Meshes

  • Park, Jin-Seok;Yoon, Sung-Hwan;Kim, Chong-Am
    • 한국전산유체공학회:학술대회논문집
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    • 2008.10a
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    • pp.378-385
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    • 2008
  • The present paper deals with the accurate and robust limiting procedure for the multi-dimensional flow analysis on unstructured meshes. The multi-dimensional limiting process (MLP) which was successfully proposed on structured grid system is extended to unstructured meshes. Based on MUSCL-type framework on unstructured meshes, the new slope limiter is devised to satisfy the MLP condition, which is quite effective to regulate the unwanted oscillations, especially on multiple dimensions. Considering the neighborhood based on the vertex of the cell, as well as the edge, this limiting strategy captures the multi-dimensional flow features very accurately with the proper stencils. From the various numerical results, these desirable characteristics of the proposed limiting strategy are clearly shown.

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Multi Objective Vehicle and Drone Routing Problem with Time Window

  • Park, Tae Joon;Chung, Yerim
    • Journal of the Korea Society of Computer and Information
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    • v.24 no.1
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    • pp.167-178
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    • 2019
  • In this paper, we study the multi-objectives vehicle and drone routing problem with time windows, MOVDRPTW for short, which is defined in an urban delivery network. We consider the dual modal delivery system consisting of drones and vehicles. Drones are used as a complement to the vehicle and operate in a point to point manner between the depot and the customer. Customers make various requests. They prefer to receive delivery services within the predetermined time range and some customers require fast delivery. The purpose of this paper is to investigate the effectiveness of the delivery strategy of using drones and vehicles together with a multi-objective measures. As experiment datasets, we use the instances generated based on actual courier delivery data. We propose a hybrid multi-objective evolutionary algorithm for solving MOVDRPTW. Our results confirm that the vehicle-drone mixed strategy has 30% cost advantage over vehicle only strategy.

The Profit Analysis of Straddle Sell by Entry-Time and Delta at System Trading (시스템 트레이딩에서 진입시점과 델타에 따른 스트래들 매도의 성능 분석)

  • Ko, Young Hoon;Kim, Yoon Sang
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.6 no.1
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    • pp.151-157
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    • 2010
  • This paper proposes the Pyramid strategy which is based on the straddle sell. The Pyamid strategy has multi-entry features with starting date and delta parameters. And It is hedged against a loss by mutual trades and dynamic ripples. This paper analyzes the profit and MDD(maximum draw down) of the Pyramid strategy on system trading. The portfolio tool is used for the experiment which is one of the Multicharts' package. The Multicharts is a good trading system of recent years. For the experiment, three call options and three put options are used at october in 2009. Two parameters are used which are the starting date from first October to twentieth October in 2009 and delta from eight percent to fifty percent. As a result, the profit of composite option is about 3 million won. If the strategy starts before the beginning of option month, investors feel uncomfortable because of a large MDD. If a delta belows 20%, it shows high profit and the ratio of profit and MDD builds up a low value. However a low delta makes frequent trades and results in a loss unless increasing entry levels which mean more amount of investment. This work provides a safer trade system than native option trades. It is important how much levels of multi-entry are acceptable. And an amount of investment with appropriate levels of multi-entry is a subject of a future study.

A Study on the Algorithm for Adaptive Odd/Even Multi-shell Median Filter (가변 문턱조건을 이용한 odd/even median filter 알고리즘)

  • 조상복;이일권
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.495-498
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    • 1999
  • In this paper, we propose the adaptive Odd/Even Multi-shell Median Filter(adaptive O/E MMF) to improve the defect that Modified Multi-shell Median Filter(MMMF) can not recover missing lines of vertical and cross direction. This filter uses odd/even multi-shells and new proposed threshold strategy The performance of the proposed filter is evaluated over image 'airfield 'by using MATLAB. As the proposed threshold strategy eliminate the number of redundant replacement, it suppresses impulse noise and recovers missing lines.

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