• 품질경영학회지
• /
• 제47권1호
• /
• pp.87-96
• /
• 2019

Purpose: The purpose of this paper is to determine an optimal production time for economic production quantity model with preventive maintenance and random defective rate as the function of a machinery deteriorates. Methods: If a machinery shifts from "in-control" state to "out-of-control" state, a proportion of defective items being produced increases. It is assumed that time to state shift is a random variable and follows an arbitrary distribution. The elapsed time until process shift decreases stochastically as a production cycle repeats and quasi-renewal process is used to implement for production facilities to deteriorate. Results: When the exponential parameter for exponential distribution increases, the optimal production time increases. When Weibull distribution is considered, the optimal production time is closely affected by the shape parameter of Weibull distribution. Conclusion: A mathematical model is suggested to find optimal production time and optimal number of production cycles and numerical examples are implemented to validate the patterns for changes of optimal times under different parameters assumptions. The real application is implemented using the proposed approach.

• 품질경영학회지
• /
• 제52권2호
• /
• pp.357-376
• /
• 2024

Purpose: The purpose of this study is to design an objective and comparable diagnostic system for diagnosing the technology level of military maintenance depots and verify its actual applicability. Methods: Literature Review, Capability Maturity Model Integration, Analytic Hierarchy Process. Results: Military maintenance depot maintenance quality level diagnosis items, Maintenance quality level by maintenance technology area, Guidelines for diagnosing maintenance quality level, Quality level comparison results by area and implications for improvement. Conclusion: In order to systematically evaluate the maintenance quality of military maintenance depots, this study was conducted with the goal of designing an overall maintenance quality diagnosis system, including diagnosis areas, diagnosis items, and a diagnosis score award system, by improving the existing evaluation method. In addition, the newly developed maintenance quality diagnosis system was applied to actual evaluation activities and the results were returned to members, confirming the usefulness of the developed maintenance quality diagnosis system in the field.

• 품질경영학회지
• /
• 제39권2호
• /
• pp.170-178
• /
• 2011

In general, a software fault detection phenonenon is described by a software reliability model based on a nonhomogeneous Poisson process(NHPP). In this paper, we propose a software reliability growth model considering the differences of the software environments in both the testing phase and the operational phase. Also, we consider the problem of determining the optimal release time and the optimal warranty period that minimize the total expected software cost which takes account of periodic software maintenance(e.g. patch, update, etc). Finally, we analyze the sensitivity of the optimal release time and warranty period based on the fault data observed in the actual testing process.

• Smart Structures and Systems
• /
• 제26권4호
• /
• pp.533-544
• /
• 2020

Effective bridge maintenance reduces bridge operation costs and extends its service life. The possibility of storing bridge life-cycle data in a 3D parametric model of the bridge through Bridge Information Modeling (BrIM) provides new opportunities to enhance current practices of bridge maintenance management. This study develops a Decision Support System (DSS), namely BrDSS, which employs BrIM and an efficient optimization model for bridge maintenance planning. The BrIM model in BrDSS extracts basic data of elements required for the optimization process and visualizes the inspection data and the optimization results to the user to help in decision makings. In the optimization module of the DSS, the specifically formulated Genetic Algorithm (GA) eliminates the chances of producing infeasible solutions for faster convergence. The practicality of the presented DSS was explored by utilizing the DSS in the maintenance planning of a bridge under operation in the southwest of Iran.

• 한국IT서비스학회지
• /
• 제20권1호
• /
• pp.81-92
• /
• 2021

As the degree of economic development of society increases, the maintenance issues on the existing social overhead capital becomes essential. Accordingly, the adaptation of the concept of Level of service in highway maintenance is indispensable. It is also crucial to manage and perform the service level such as road assets to provide universal services to users. In this regards, the purpose of this study is to improve the maintenance service rating model and to focus on the assessment items and weights among the improvements. Particularly, in determining weights, an Analytic Hierarchy Process (AHP) is performed based on the survey response results. After then, this study conducts unsupervised neural network models such as Self-Organizing Map (SOM) and Davies-Bouldin (DB) Index to divide proper sub-groups and determine priorities. This paper identifies similar cases by grouping the results of the responses based on the similarity of the survey responses. This can effectively support decision making in general situations where many evaluation factors need to be considered at once, resulting in reasonable policy decisions. It is the process of using advanced technology to find optimized management methods for maintenance.

• 한국정보과학회논문지:소프트웨어및응용
• /
• 제36권9호
• /
• pp.718-731
• /
• 2009

소프트웨어 유지보수는 기존의 하자 유지보수 개념에서 운영관리 및 서비스의 향상을 위해 지속적인 개선이 요구되고 있다. 본 연구에서는 K사에서 수행중인 4개의 유지보수 프로젝트를 기반으로 소프트웨어 유지보수 성숙도 모델과 평가지표를 제안한다. 이를 위해 SMMM, ITSMM, ITIL을 기반하여 13개의 프로세스 영역과 64개의 평가지표를 도출하고, 도출된 64개의 평가지표를 5점 척도로 설문 평가하여 그 결과를 기반으로 성숙도 모델의 수준을 분류하여 K사의 성숙도 모델을 구축한다. 그리고 K사의 성숙도 모델을 검증 및 개선하기 위하여 K사의 설문평가 점수를 분석하여 평가지표의 개선방안을 제안하고, K사의 성숙도 모델이 소프트웨어 유지보수의 개선 방안을 어떻게 나타내는지를 확인하기 위하여 제안한 소프트웨어 유지보수 성숙도 모델을 K사의 4개의 프로젝트를 대상으로 하여 성숙도 평가를 수행하고, 그 결과를 기반으로 개선방안을 제시하였다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.27-37
• /
• 2011

Currently, in the course of introducing rolling stocks, RAMS standard and management by system engineering method apply to rolling stock system. Technical elements and results applied in system introduction phase are just used in acquisition stage, and these are not applied to the standard in railway site. Therefore, it is difficult to apply to standardized technology and quality assurance measure. Due to the establishment of the EU, railway operation system is internationalized and the international railway standards are being discussed in various ways. In addition, standardization is expanded from manufacture to operation and maintenance. It is to provide consistent standard in quality, cost calculation of maintenance technology, maintenance technology and quality assurance in case of international railway safety incidents. Therefore, this study is to find technology, quality and cost management model to be used for choosing railway-operation guidance by considering how technologies & quality have changed in system life cycle, compared with estimated standards, based on the technologies & quality-related result in the process of getting new rolling stocks and management guidance for operation & maintenance process.

• 산업공학
• /
• 제25권1호
• /
• pp.127-133
• /
• 2012

This paper considers the preventive maintenance scheduling problem of the cluster tool which is one of the most important manufacturing equipments in the next-generation semiconductor production environment. We define a random process that expresses the successive amount of chemicals accumulating inside the tool. Based on the renewal theory, we find the expected value and probability distribution of the time that the amount of accumulated chemicals exceeds a predetermined level. For a given probability that the accumulated chemicals exceeds the predetermined level we present a method to obtain the number of chamber operations to perform the preventive maintenance of that chamber. In addition, a method to get the preventive maintenance schedule for the whole cluster tool is presented. A numerical example is provided to illustrate our method.

• 한국건설관리학회논문집
• /
• 제22권1호
• /
• pp.116-124
• /
• 2021

건설공사의 설계 및 시공단계에 BIM 모델의 활용성이 증대되면서 유지관리단계의 BIM 활용성 증대도 예상되고 있다. 유지관리단계에는 이미 작업이 완료된 설계 및 시공단계에 생성된 BIM 객체들을 사용하게 되므로, 활용하는 BIM 객체가 설계단계에 제작된 인증 모델인지 신뢰도 검증이 필요하다. 특히 철도시설물과 같이 토목, 건축, 전기, 신호, 궤도 등 다양한 공정과 기관으로 구성된 BIM 활용 프로젝트에서는 BIM 모델의 신뢰도가 더욱 중요도를 갖게 된다. 본 연구에서는 유지관리단계에서 사용하는 BIM 모델의 신뢰도를 확보하기 위한 방안으로 블록체인기술을 사용하는 방법을 제안하고 있으며, 이를 위해 BIM에 블록체인기술을 적용하기 위한 블록의 구조와 상세 프로세스를 구성하였다. 또한 이러한 과정을 실제 시설물의 BIM 모델에 적용하여 블록을 생성함으로써 블록체인 기술이 BIM 모델의 신뢰도 확보를 위한 도구로 사용될 수 있음을 확인하였다.

• 응용통계연구
• /
• 제23권3호
• /
• pp.573-584
• /
• 2010

This paper considers the differences in the software execution environments in the testing phase and the operational phase to determine the optimal release time and warranty period of software systems. We formulate equations for the total expected software cost until the end of the software life cycle based on the NHPP. In addition, we derive the optimal release time that minimizes the total expected software cost for an imperfect debugging software reliability model. Finally, we analyze the sensitivity of the optimal testing and maintenance design related to variation of the cost model parameters based on the fault data observed in the actual testing process, and discuss the quantitative properties of the proposed model.