• Journal of Korean Society for Quality Management
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• v.47 no.1
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• pp.87-96
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• 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.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1412-1422
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• 2016

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.886-891
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• 2004

The process of determining whether, when, where and how to intervene, of deciding on optimum allocation of resources and minimizing the cost is a very complex problem: different track sections tend to behave differently under the effects of loading; decision-making processes for maintenance work are closely interrelated technically and economically; decision-making for maintenance plans is based on a large quantity of technical and economic information, extensive knowledge and above all experience. For that reason, It is considered very important to develope objective and computer-aided decision-making support system for track maintenance plan. On this paper, we made a survey of the state-of-art of decision-making support systems for track maintenance which were developed and used abroad and reviewed requirements of system and present the plan of develope decision-making support system for track maintenance appropriate to local condition.

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.16 no.2
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• pp.13-21
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• 2012

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.288-290
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• 2007

This paper presents a visualization application using 3D-graphics for effective maintenance of power equipment. The maintenance algorithm implemented in the application is based on Condition-Based Maintenance (CBM) and Reliability -Centered Maintenance (RCM). The main frame of the developed application was made up based on Windows Application Programming Interface (API) and Microsoft Fundamental Classes (MFC). In order to develop the interactive 3D application, the WorldToolKit (WTK) library based on Open GL was used. Also Text-to-Speech (TTS) technology was used to enhance the efficiency of operators. The developed application can help the power system operators to intuitively recognize the present state and maintenance information of the equipment.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.246-248
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• 2006

This paper presents a visualization application using 3D-graphics for effective maintenance of power equipments. The maintenance algorithm implemented in the application is based on Condition-Based Maintenance (CBM) and Reliability-Centered Maintenance (RCM). The main frame of the developed application was made up based on visual C++ (MFC). In order to develop the interactive 3D application, the WorldToolKit library based on Open GL was used. The developed application can help the power system operators to intuitively recognize the present state and maintenance information of the equipments.

• Journal of Applied Reliability
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• v.12 no.1
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• pp.1-12
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• 2012

The quality of a part has directly effect on part reliability. In the basis of MIL-HDBK-217F model, it is the determined rule that part's quality level should follow its nominal one written in its specification. If quality information is unknown, quality level of the part should be determined as 'Lower'. However, the prediction model is said to be short in reflecting parts applying 'state-of-the-art' technology and result in over-estimated failure rate by some reliability-related authorities or research institutes. In this study, the reliability prediction results by the model of MIL-HDBK-217F and Telcordia SR-332 are compared and analyzed to verify whether the statement is reasonable or not.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.149-157
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• 2003

The purpose of this paper is to quantitatively investigate aging state of epoxy coating on containment structure at nuclear power plant. In order to evaluate an physical bonding of the epoxy coating, adhesion test was performed on a degraded epoxy coating on concrete specimens fabricated by accelerated aging experiment. In addition, impedance data by ultrasonic test were measured to compare with adhesion data. From almost 50 % of the specimens, aging phenomena of epoxy coating such as pin hole, blistering was discovered. To improve reliability on quality degradation of epoxy, co-relation between two kinds of different data was analyzed. By tracing co-related these data, it was possible to figure out physical state of as-built epoxy coating. The possibility to develop new methodology of time - dependent aging state on epoxy coating was found and discussed.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.507-508
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• 2013

International Roughness Index (IRI) has been widely used by state DOTs to quantify pavement smoothness. When pavement condition falls below certain IRI thresholds, corresponding pavement maintenance treatments should be considered for application. Selection of appropriate IRI thresholds is essential to tactical allocation of limited resources to improve the conditions of states' roadway systems. This selection process is often challenging, however, because IRI thresholds are largely determined by Perceived Ride Quality (PRQ), and PRQ differs in each state. In this paper, a framework is proposed to address this problem. Passenger raters will be randomly selected from predetermined geographic locations, and their PRQ ratings collected. Taking this perceived ride data, along with other data collected, a statistical analysis will be conducted to establish the relationship between measured IRI values and PRQ. Appropriate IRI thresholds will then be determined. Once this framework is implemented, state DOTs could make informative maintenance decisions, which are expected to greatly enhance the public perception of pavement conditions in today's challenging economy.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.4
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• pp.35-55
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• 2001

Recently, as tunnel structures are getting older and decrepit, many tunnel inspections are carried out for evaluating the tunnel state and safety. But, because there is no exact standard for tunnel state and safety, depending on subjective decision, the new standard to assess the tunnel state is required. The existing standard including mainly the assessment of the state of tunnel lining is not considered the characteristics of tunnel as underground structures. Also, the item of assessment and process of grading and classifying the state of tunnel is not objective and systemetic. In this study, new standard for assessment of tunnel state is presented for improving the problems in evaluating the tunnel state and safety. In the new standard, the new items of assessment including geotechnical condition were selected and graded, the process in classifying the tunnel state is quantitative for objective assessment for tunnel state. This new standard and method is practically used in effective safety inspection and diagnosis and tunnel maintenance.