• Title/Summary/Keyword: PERT

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Fundamental Research on the Development of a Risk Based Decision Support System for Maritime Accident Response: Focused on Oil Tanker Grounding (위험도기반 해양사고 초기대응 지원 시스템 개발 기초연구: 유조선 좌초사고를 중심으로)

  • Na, Seong;Lee, Seung-Hyun;Choi, Hyuek-Jin
    • Journal of Navigation and Port Research
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    • v.40 no.6
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    • pp.391-400
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    • 2016
  • A number of maritime accidents, and accident response activities, including the command and control procedures that were implemented at accident scenes, are analyzed to derive useful information about responding to maritime accidents, and to understand how the chain of events developed after the initial accident. In this research, a new concept of a 'risk based accident response support system' is proposed. In order to identify the event chains and associated hazards related to the accident response activities, this study proposes a 'Brainstorming technique for scenario identification', based on the concept of the HAZID technique. A modified version of Event Tree Analysis was used for quantitative risk analysis of maritime accident response activities. PERT/CPM was used to analyze accident response activities and for calculating overall (expected) response activity completion time. Also, the risk based accident response support system proposed in this paper is explained using a simple case study of risk analysis for oil tanker grounding accident response.

Risk assessment for norovirus foodborne illness by raw oyster (Ostreidae) consumption and economic burden in Korea

  • Yoo, Yoonjeong;Oh, Hyemin;Lee, Yewon;Sung, Miseon;Hwang, Jeongeun;Zhao, Ziwei;Park, Sunho;Choi, Changsun;Yoon, Yohan
    • Fisheries and Aquatic Sciences
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    • v.25 no.5
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    • pp.287-297
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    • 2022
  • The objective of this study was to evaluate the probability of norovirus foodborne illness by raw oyster consumption. One hundred fifty-six oyster samples were collected to examine the norovirus prevalence. The oyster samples were inoculated with murine norovirus and stored at 4℃-25℃. A plaque assay determined norovirus titers. The norovirus titers were fitted with the Baranyi model to calculate shoulder period (h) and death rate (Log PFU/g/h). These kinetic parameters were fitted to a polynomial model as a function of temperature. Distribution temperature and time were surveyed, and consumption data were surveyed. A dose-response model was also searched through literature. The simulation model was prepared with these data in @RISK to estimate the probability of norovirus foodborne. One sample of 156 samples was norovirus positive. Thus, the initial contamination level was estimated by the Beta distribution (2, 156), and the level was -5.3 Log PFU/g. The developed predictive models showed that the norovirus titers decreased in oysters under the storage conditions simulated with the Uniform distribution (0.325, 1.643) for time and the Pert distribution (10, 18, 25) for temperature. Consumption ratio of raw oyster was 0.98%, and average consumption amount was 1.82 g, calculated by the Pert distribution [Pert {1.8200, 1.8200, 335.30, Truncate (0, 236.8)}]. 1F1 hypergeometric dose-response model [1 - (1 + 2.55 × 10-3 × dose)-0.086] was appropriate to evaluate dose-response. The simulation showed that the probability of norovirus foodborne illness by raw oyster consumption was 5.90 × 10-10 per person per day. The annual socioeconomic cost of consuming raw oysters contaminated with norovirus was not very high.

A Study on the Development TOC(Theory of Constraints) based Manufacturing system (TOC(Theory of Constraints)를 기반으로 한 최적생산시스템 연구)

  • 류인화;윤희성;김창은
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2000.04a
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    • pp.538-541
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    • 2000
  • Goldratt박사에 의해 제창된 TOC(Theory of Constraints)는 제약조건을 찾아 개선시켜 없애고 시스템 심과를 높일 수 있는 방안을 찾는 제약이론이다. 생산공정을 포함한 모든 분야에서 제약이란 없을 수가 없다. 따라서 기존의 MRP나 PERT/CPM과 같은 무한 자원 스케줄링으로는 예상하지 못한 문제가 도출될 수 밖에 없는 한계를 제약공정의 자원능력이 유한하다는 가정에서 출발하는 제약이론으로 자원활용의 최적화를 도모할 수 있다. 본 논문에서는 TOC와 많은 유사점을 가지고 있는 생산시스템인 JIT와 비교하여 아직 국내에는 활발한 연구가 이루어지고 있지 않은 TOC를 기반으로 최적 생산시스템을 연구하고자 한다.

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Development of Scheduling Software for Flexible Manufacturing System (FMS운용을 위한 일정계획용 소프트웨어)

  • 윤덕균;황의철
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.14 no.24
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    • pp.53-69
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    • 1991
  • This paper is concerned with software developments for scheduling and sequencing of FMS. The scheduling algorithms are developed for 3 types of FMS:single machine type FMS, flowshop type FMS. assembly line type FMS. For the single machine type FMS. full enumeration algorithm is used. For the flowshop type FMS heuristic algorithms are developed. For the assembly type FMS the exsisting PERT/CPM algorithm is applied. Numerical examples are presented for illustration of each algorithm. Each soft ware program list are attached as appendices.

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A method of Calculating Optimal Duration and Cost Using Monte Carlo Simulation and Linear Programming (몬테카를로 시뮬레이션과 선형계획법을 이용한 최적의 일정 및 비용 산정방법)

  • Kim Yong-Deuk;Lee Young-Dae
    • Proceedings of the Korean Institute Of Construction Engineering and Management
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    • 2004.11a
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    • pp.210-215
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    • 2004
  • In can occur to many problems on progressing step without close scope definition, interrelation definition between activities, resource plan, and schedule plan on planning step. But it have not closely defined performance system on planning step because of many constraints of domestic construction industry. Therefore this paper intends to discuss a method of calculating optimal cost and duration using Linear Programming that solves maximing or minimizing problems among decision making methodology and Monte Carlo Simulation that decreases to probability errors. With outcoms applying Linear programming and Monte Carlo Simulation for calculating optimal cost and duration, follow as : With outcomes applying Monte Carlo Simulation, it could calculate reliable estimator about project duration through removing various constraints. With outcomes applying Linear programming, it could calculate optimal value about project cost through defining various variables and constraints on many activities.

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Web-based Three-step Project Management Model and Its Software Development

  • Hwang Heung-Suk;Cho Gyu-Sung
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2006.05a
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    • pp.373-378
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    • 2006
  • Recently the technical advances and complexities have generated much of the difficulties in managing the project resources, for both scheduling and costing to accomplish the project in the most efficient manner. The project manager is frequently required to render judgments concerning the schedule and resource adjustments. This research develops an analytical model for a schedule-cost and risk analysis based on visual PERT/CPM. We used a three-step approach: 1) in the first step, a deterministic PERT/CPM model for the critical path and estimating the project time schedule and related resource planning and we developed a heuristic model for crash and stretch out analysis based upon a time-cost trade-off associated with the crash and stretch out of the project. 2) In second step, we developed web-based risk evaluation model for project analysis. Major technologies used for this step are AHP (analytic hierarchy process, fuzzy-AHP, multi-attribute analysis, stochastic network simulation, and web based decision support system. Also we have developed computer programs and have shown the results of sample runs for an R&D project risk analysis. 3) We developed an optimization model for project resource allocation. We used AHP weighted values and optimization methods. Computer implementation for this model is provided based on GUI-Type objective-oriented programming for the users and provided displays of all the inputs and outputs in the form of GUI-Type. The results of this research will provide the project managers with efficient management tools.

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Project Schedule Risk Assessment Based on Bayesian Nets (베이지안넷 기반의 프로젝트 일정리스크 평가)

  • Sung, Hongsuk;Park, Chulsoon
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.39 no.1
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    • pp.9-16
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    • 2016
  • The project schedule risk in the engineering and facility construction industry is increasingly considered as important management factor because the risks in terms of schedule or deadline may significantly affect the project cost. Especially, the project-based operating companies attempt to find the best estimate of the project completion time for use at their proposals, and therefore, usually have much interest in accurate estimation of the duration of the projects. In general, the management of projects schedule risk is achieved by modeling project schedule with PERT/CPM techniques, and then performing risk assessment with simulation such as Monte-Carlo simulation method. However, since these approaches require the accumulated executional data, which are not usually available in project-based operating company, and, further, they cannot reflect various schedule constraints, which usually are met during the project execution, the project managers have difficulty in preparing for the project risks in advance of their occurrence in the project execution. As these constraints may affect time and cost which role as the crucial evaluation factors to the quality of the project result, they must be identified and described in advance of their occurrence in the project management. This paper proposes a Bayesian Net based methodology for estimating project schedule risk by identifying and enforcing the project risks and its response plan which may occur in storage tank engineering and construction project environment. First, we translated the schedule network with the project risks and its response plan into Bayesian Net. Second, we analyzed the integrated Bayesian Net and suggested an estimate of project schedule risk with simulation approach. Finally, we applied our approach to a storage tank construction project to validate its feasibility.

The design of outlet in inter-cross slope with tunnel which it applied forming artificial ground (인공지반을 적용한 사교하는 사면에서의 터널 갱구부 설계)

  • Park, Chal-Sook;Kwan, Han;Lee, Kyu-Tak;Kim, Bong-Jae;Yun, Yong-Jin;Kim, Kwang-Hee
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1532-1548
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    • 2008
  • The tunnel type spillways is under construction to increasing water reservoir capacity in Dae-am dam. The tunnel outlet was planned to be made after installing slope stabilization system on natural slope there. Generally, the tunnel outlet is made perpendicularly to the slope, but in this case, it had to be made obliquely to the slope for not interrupting flow of river. Because of excavation in condition of natural slope caused to deflecting earth pressure, the outlet couldn't be made. So, artificial ground made with concrete that it was constructed in the outside of tunnel for producing the arching effect which enables to make a outlet. We were planned tunnel excavation was carried out after artificial ground made. Artificial ground made by poor mix concrete of which it was planned that the thickness was at least 3.0m height from outside of tunnel lining and 30cm of height per pouring. Spreading and compaction was planned utilized weight of 15 ton roller machine. In order to access of working truck, slope of artificial ground was designed 1:1.0 and applied 2% slope in upper pert of it for easily drainage of water. In addition to, upper pert of artificial ground was covered with soil, because of impaction of rock fall from upper slope was made minimum. The tunnel excavation of the artificial ground was designed application with special blasting method that it was Super Wedge and control blasting utilized with pre-percussion hole.

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Application of Perturbation-based Sensitivity Analysis to Nuclear Characteristics (섭동론적 감도해석 이론의 원자로 핵특성에의 응용)

  • Byung Soo Lee;Mann Cho;Jeong Soo Han;Chung Hum Kim
    • Nuclear Engineering and Technology
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    • v.18 no.2
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    • pp.78-84
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    • 1986
  • An equation of material number density sensitivity coefficient is derived using first-order perturbation theory. The beginning of cycle of Super-Phenix I is taken as the reference system for this study. Effective multiplication factor of the reference system is defined as system response function and fuel enrichment and fuel effective density are chosen for the variation of reference input data since they are described by material number density which is a component of Boltzmann operator. The nuclear computational code system (KAERI-26 group cross section library/1DX/2DB/PERT-V) is employed for this calculation. Sensitivity coefficient of fuel enrichment on effective multiplication factor is 4.576 and sensitivity coefficient of effective fuel density on effective multiplication factor is 0.0756. This work shows that sensitivity methodology is lesser timeconsuming and gives more informations on important design parameters in comparison with the direct iterative calulation through large computer codes.

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