• Title/Summary/Keyword: Sequence Maintenance

Search Result 113, Processing Time 0.051 seconds

Development of Maintenance Sequence System by Using Modified FMEA and CBR (FMEA 개념과 사례베이스추론 기법을 이용한 보전작업순서결정시스템의 개발)

  • 김광만
    • Journal of the Korea Safety Management & Science
    • /
    • v.3 no.4
    • /
    • pp.103-112
    • /
    • 2001
  • In Factory, as the number of machine is increased the more maintenance efforts are necessary. Multi maintenance issues may occur at a certain time and the determination of maintenance sequence is needed. In this study, we first compare the priority of machines and the impact value using modified FMEA(Failure Mode Effect and Analysis) method. Also, CBR(Case-based Reasoning) approach is applied to retrieve similar fault cases of current machine problem. The proposed methodology will be useful to implement decision support system of maintenance sequence for CMMS/EAM (Computerized Maintenance Management System/Enterprise Asset Management).

  • PDF

The Reasonable Concrete-Placing Methods and Sequences of Composite Steel Bridge (강합성형 교량의 합리적인 타설방법과 순서에 관한 연구)

  • Jo, Byung-Wan;Seo, Sug-Gu
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.3 no.2
    • /
    • pp.205-212
    • /
    • 1999
  • Recently, unexpected cracks in the concrete deck slab of composite steel bridges have been widely reported at an early age of concrete placing due to the concrete placing sequence and methods. Accordingly, the analytical research was carried out to verify the negative moment at an internal supports due to the several concrete pouring sequence and to determine the reasonable concrete placing method on the deck slab of composite steel bridge. The results show that the conventional concrete-placing method, which pours concrete first on the positive moment regions and then negative regions, leads to the minimum moment at an internal supports. However, the conventional method produces two impractical construction joints on every spans and makes field engineer to pour concrete continuously. In conclusion, this concrete-placing method was verified to be reasonable only when the construction joint was placed at the $\frac{5}{8}l{\sim}\frac{6}{8}l$ location of the middle span.

  • PDF

Improvement of Memory Efficiency for Alternative Sequence in Process Control System Described by SFC (SFC로 설계된 공정제어에서 선택시퀀스의 메모리효율향상)

  • You, Jeong-Bong
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.24 no.5
    • /
    • pp.55-61
    • /
    • 2010
  • When we design the control system used Programmable Logic Controller(PLC) by Sequential Function Chart(SFC), if we use a SFC, it is easy to know the sequential flow of control, to maintenance the controller and to describe a program. We program a SFC by a unique sequence, an alternative sequence and a parallel sequence. If we program a SFC by a alternative sequence, the memory size of a alternative sequence must be larger than the memory size of a unique sequence. Therefore this thesis show an efficient method to reduce a memory size and we confirmed its feasibility through actual example.

Optimum maintenance scenario generation for existing steel-girder bridges based on lifetime performance and cost

  • Park, Kyung Hoon;Lee, Sang Yoon;Yoon, Jung Hyun;Cho, Hyo Nam;Kong, Jung Sik
    • Smart Structures and Systems
    • /
    • v.4 no.5
    • /
    • pp.641-653
    • /
    • 2008
  • This paper proposes a practical and realistic method to establish an optimal lifetime maintenance strategy for deteriorating bridges by considering the life-cycle performance as well as the life-cycle cost. The proposed method offers a set of optimal tradeoff maintenance scenarios among other conflicting objectives, such as minimizing cost and maximizing performance. A genetic algorithm is used to generate a set of maintenance scenarios that is a multi-objective combinatorial optimization problem related to the lifetime performance and the life-cycle cost as separate objective functions. A computer program, which generates optimal maintenance scenarios, was developed based on the proposed method using the life-cycle costs and the performance of bridges. The subordinate relation between bridge members has been considered to decide optimal maintenance sequence and a corresponding algorithm has been implemented into the program. The developed program has been used to present a procedure for finding an optimal maintenance scenario for steel-girder bridges on the Korean National Road. Through this bridge maintenance scenario analysis, it is expected that the developed method and program can be effectively used to allow bridge managers an optimal maintenance strategy satisfying various constraints and requirements.

Integrating Machine Reliability and Preventive Maintenance Planning in Manufacturing Cell Design

  • Das, Kanchan;Lashkari, R.S.;Sengupta, S.
    • Industrial Engineering and Management Systems
    • /
    • v.7 no.2
    • /
    • pp.113-125
    • /
    • 2008
  • This paper presents a model for designing cellular manufacturing systems (CMS) by integrating system cost, machine reliability, and preventive maintenance (PM) planning. In a CMS, a part is processed using alternative process routes, each consisting of a sequence of visits to machines. Thus, a level of 'system reliability' is associated with the machines along the process route assigned to a part type. Assuming machine reliabilities to follow the Weibull distribution, the model assigns the machines to cells, and selects, for each part type, a process route which maximizes the overall system reliability and minimizes the total costs of manufacturing operations, machine underutilization, and inter-cell material handling. The model also incorporates a reliability based PM plan and an algorithm to implement the plan. The algorithm determines effective PM intervals for the CMS machines based on a group maintenance policy and thus minimizes the maintenance costs subject to acceptable machine reliability thresholds. The model is a large mixed integer linear program, and is solved using LINGO. The results point out that integrating PM in the CMS design improves the overall system reliability markedly, and reduces the total costs significantly.

A pragmatic algorithm for the Minimum Railway Stock Maintenance Routing Problem (최소차량운용문제에 대한 실용적 해법)

  • Hong Seong-Pil;Kim Gyeong-Min;Lee Gyeong-Sik;Park Beom-Hwan;Hong Sun-Heum
    • Proceedings of the Korean Operations and Management Science Society Conference
    • /
    • 2006.05a
    • /
    • pp.25-32
    • /
    • 2006
  • Given a schedule of train to be routed by a Railway Stock, Railway Stock Routing Problem determine a sequence of train while satisfying turnaround time and maintenance restrictions. The objective is to minimize the Railway Stock during a week and each day simultaneously. And we prove that Railway Stock Routing Problem with maintenance restrictions is NP-hard. In this paper, we present two stage approaches that solve the Railway Stock Routing Problem in a reasonable time. In first stage we relax maintenance restrictions and formulate as a Min-cost-flow problem. Then, in the second stage, we attempt to satisfy maintenance restrictions using ours heuristic algorithm. We show the computational result of applying to an actual train schedule data.

  • PDF

Development of Integrated Method and Tool for Railway Risk Assessment (철도 위험도 통합 평가 방법 및 도구 개발)

  • Han, Sang-Hoon;Ahn, Kwang-Il;Wang, Jong-Bae;Lee, Ho-Joong
    • Proceedings of the KSR Conference
    • /
    • 2006.11b
    • /
    • pp.1132-1139
    • /
    • 2006
  • Railway risk is evaluated by a method of linking event trees and fault trees as the general PSA(Probabilistic Safety Assessment) model for the risk assessment of complex systems. Accident scenarios causing undesirable events are modeled by event trees comprised of several accident sequences. Each branch located in the accident progression of the event tree is modeled by an fault tree or can be represented by some value too simply. We usually evaluate the frequency of the whole sequence by adding them after calculating the frequency of each sequence at a time. However, since there are quite a number of event trees and fault trees in the railway risk assessment model, the number of sequence to evaluate increases and preparation for the risk assessment costs much time all the more. Also, it may induce errors when analysts perform the work of quantification. Therefore, the systematic maintenance and control of event trees and fault trees will be essential for the railway risk assessment. In this paper we introduce an integrated assessment method using one-top model and develop a risk assessment tool for the maintenance and control of the railway risk model.

  • PDF

An Efficient Method of Remote Control for Select Sequence in Process Control (공정제어에서 선택시퀀스를 위한 효율적인 리모트 콘트롤 제어방법)

  • Kong, Heon-Tag;Kim, Chi-Su;You, Jeong-Bong
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.11 no.1
    • /
    • pp.107-112
    • /
    • 2010
  • When we design the control system used Programmable Logic controller(PLC), if we program a Sequential Function Chart(SFC), It is easy to understand the sequential flow of control, to maintenance the controller and to describe a program. SFC language is programmed by a single sequence, a select sequence and a parallel sequence. In a select sequence, when the select step is error, the whole process is stopped. If the error step has no connection the whole process, the loss is down when we debugging the program without stopping the whole process. Therefore, this thesis shows the efficient method of remote control for select sequence and we confirmed its feasibility through actual example.

Development of extended safe petri net model for discrete system control and scanning algorithm for real time control (비연속 시스템 제어를 위한 확장된 safe petri net 모델과 실시간제어를 위한 scanning algorithm의 개발)

  • 황창선;서정일;이재만
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1988.10a
    • /
    • pp.338-342
    • /
    • 1988
  • Recently, in sequence control systems, high flexibility and maintenance of control software are required. This is because product life cycles become shorter and control specification must be changed frequently. The authors extend the concept of Safe Petri Net to develop the design and analysis tool for sequence control systems taking the safeness and notation of input/output functions into consideration. Extended Safe Petri Net (S-Net) is proposed as such a new graph model and real time scanning algorithm based on S-Net is developed.

  • PDF

A Method of Select Sequence Control by Remote Control in Process Control designed by SFC (SFC로 설계된 공정제어에서 Remote Control에 의한 선택 시퀀스 제어 방법)

  • You, Jeong-Bong
    • Proceedings of the KIEE Conference
    • /
    • 2007.04a
    • /
    • pp.134-136
    • /
    • 2007
  • Sequential Function Chart(SFC) is very easy to grasp the sequential flow of control logic and has the compatability for a maintenance, In process control, when an error is occurred, to execute other routine by force, we control the process by remote control. In this paper, we proposed the method of select sequence control by remote control in process control designed by Sequential Function Chart(SFC).

  • PDF