• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2209-2214
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• 2010

The purpose of Reliability Centered Maintenance(Hereafter, RCM) is to enhance the effectiveness and efficiency of preventive maintenance by applying the improvement plan after analysis of existing preventive maintenance. To accomplish this, it is required to collect the failure data for equipments during operation, and to carry out the quantitative criticality analysis for each equipment. This paper shows that the case study of RCM criticality analysis based on the accumulative failure data and following improvement activity for KORAIL AIRPORT RAILROAD's E&M system.

• Journal of Korean Clinical Nursing Research
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• v.27 no.1
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• pp.85-97
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• 2021

Purpose: The purpose of this study was to develop a video education program (VEP) for the caregivers and to verify its effectiveness on the maintenance of a peripheral intravenous catheter (PIVC) among hospitalized children. Methods: The VEP was developed through a literature review, educational need assessment of caregivers, and interviews with pediatric nurses, and validation of an expert group. The effectiveness of the VEP was tested on 102 caregivers and their children in a children's hospital at D city. A nonequivalent control group pretest-posttest design was used in which different types of intervention were given to caregivers in intervention group (n=51) and control group (n=51). All caregivers received brief verbal information about the PIVC maintenance. The intervention group was additionally provided with VEP using a smartphone. Data were analyzed using SPSS/Win 21.0 program. Results: The caregivers' knowledge score on PIVC maintenance in the intervention group was significantly higher than that of the control group. The numbers of flushing in case of blockage of PIVC and gauze dressing change of the intervention group was significantly lower than those of the control group. Conclusion: These results suggest that the VEP developed in this study can be useful for the maintenance of PIVC among hospitalized children.

• Smart Structures and Systems
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• v.30 no.6
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• pp.571-582
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• 2022

Optimal life-cycle management is a challenging issue for deteriorating regional bridges. Due to the complexity of regional bridge structural conditions and a large number of inspection and maintenance actions, decision-makers generally choose traditional passive management strategies. They are less efficiency and cost-effectiveness. This paper suggests a deep reinforcement learning framework employing double-deep Q-networks (DDQNs) to improve the life-cycle management of deteriorating regional bridges to tackle these problems. It could produce optimal maintenance plans considering restrictions to maximize maintenance cost-effectiveness to the greatest extent possible. DDQNs method could handle the problem of the overestimation of Q-values in the Nature DQNs. This study also identifies regional bridge deterioration characteristics and the consequence of scheduled maintenance from years of inspection data. To validate the proposed method, a case study containing hundreds of bridges is used to develop optimal life-cycle management strategies. The optimization solutions recommend fewer replacement actions and prefer preventative repair actions when bridges are damaged or are expected to be damaged. By employing the optimal life-cycle regional maintenance strategies, the conditions of bridges can be controlled to a good level. Compared to the nature DQNs, DDQNs offer an optimized scheme containing fewer low-condition bridges and a more costeffective life-cycle management plan.

• Journal of Oral Medicine and Pain
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• v.25 no.1
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• pp.1-7
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• 2000

The purpose of this study is to investigate effects of several zinc solutions including Artemisia asiatica-containing zinc solution on concentration of oral volatile sulfur compounds(VSCs). We determined the VSCs concentration of breath of human subjects before and after use of zinc solutions(O.25% $ZnF_2$ Artemisia asiatica-containing 0.25% $ZnCl_2$ and Artemisia asiatica-containing 0.25% $ZnCl_2$ solutions) The results were as follows : 1. 0.25% $ZnCl_2$ solution was more effective than 0.25% $ZnF_2$ solution in reducing the concentration of oral VSCs and the maintenance duration of effectiveness. 2. Artemisia asiatica-containing 0.25% $ZnCl_2$ solution was more effective than Artemisia asiatica-containing 0.25% $ZnF_2$ solution in reducing the concentration of oral VSCs and the maintenance duration of effectiveness. 3. Artemisia asiatica-containing 0.25% $ZnF_2$ solution and 0.25% $ZnF_2$ solution showed no significant difference in reducing the concentration of oral VSCs and the maintenance duration of effectiveness but, Artemisia asiatica-containing 0.25% $ZnF_2$ solution was slightly more effective. 4. Artemisia asiatica-containing 0.25% $ZnCl_2$ solution and 0.25% $ZnCl_2$ solution showed no significant difference in reducing the concentration of oral VSCs and the maintenance duration of effectiveness but, Artemisia asiatica-containing 0.25% $ZnF_2$ solution was slightly more effective.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.256-263
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• 2017

Purpose: This article provides the efficiency test results of conducting depot maintenance. Method: ANOVA (analysis of variance) and ANCOVA (analysis of covariance) tests are conducted using data obtained from Defense Logistics Integrated Information System (DELIIS). Results: The result shows that although the effect of the depot maintenance is significant, some parts do not follow the overall effect of the depot maintenance. In order to solve the problem we provide some suggestions to be improved. Conclusion: For improving the combat readiness condition of K-1 main battle tank, the maintenance policies and regulation must be revised for the parts of the weakness. In addition, the collection way of the operation and maintenance data must be redesigned.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.151-161
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• 2013

This paper proposes a strategic model of linkage between productivity metrics and financial accounting metrics to properly evaluate the financial effect of TPM activities and the business performance. This linkage strategy provides a connection tool for clear communication between factory-level and headquarters that the metrics proposed by this paper ultimately improves a quality of support from the management by receiving the factors required for productivity activities in the practical field. This factor includes such as equipment, raw materials and labors. Here, we propose that chain reaction models using break down structure of productivity metrics and financial metrics enhance the knowledge sharing of KPI (Key Performance Indicator) which generally tend to create oversimplified communication between management in headquarters and employees in the practical fields. The productivity metrics include OEE(Overall Equipment Effectiveness) of TPM (Total Productive Maintenance), OLE (Overall Labor Effectiveness) of PAC(Performance and Analysis and Control) activities, and OYE (Overall Yield Effectiveness) of TMM(Total Material Management) activities. The financial accounting metrics include ROE(Return on Equity), ROA(Return on Asset), and AVR(Added-Value Rate). The suggested chain reaction model selects the financial metrics as initial stage and branch down until final stage of productivity metrics. When demand exceeds supply, an ideal speed rate, the lean OEE strategy can be initially applied to reduce the gap between the demand and supply, then apply variable costing to estimate correct amount of operating profit. In addition, the paper presents a new type of model for linkage between financial accounting metrics including CAPEX(Capital Expenditure), OPEX(Operating Expenditure), EVA(Economic Added Value), DCL(Degree of Combined Leverage), and TPM productivity activities including AM(Autonomous Maintenance), PM(Preventive Maintenance), MP(Maintenance Prevention) and QM(Quality Maintenance). In order to support the evidence of proposed linkage strategy, a case analysis on 52 projects from national TPM contest from 2011 to 2012 is analyzed. The case presents the classification of CAPEX and OPEX activities from TPM, and proposes the correct implementation of financial effect for TPM projects.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.191-198
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• 2014

Korea Hydro & Nuclear Power Co. (KHNP) has developed and implemented the maintenance effectiveness monitoring (MR) programs for the operating nuclear power plants. MR programs are developed by reflecting design characteristics of the operating nuclear power plants to monitor the plant performance for improving the safety and reliability. Recently, KHNP has developed the MR program for APR1400 safety related systems to establish the advanced maintenance system and will verify the suitability of the MR program through evaluating initial performance. Consequently, it is expected that the safety of the new plant will be improved by developing and implementing the MR program.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2058-2060
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• 2002

The demand for safety and reliability of Nuclear Power Plants (NPPs) has been constantly increasing and economical operation is also an important issue. Developing and adopting predictive maintenance technology for the major systems or equipment is considered as one way to achieve these goals. This paper suggests the predictive maintenance methodology that can be applied to NPPs and describes a sample application of the Rod Control System (RCS) to verify the effectiveness of the methodology. It is expected that the same methodology can be adopted for other systems of NPPs and general industry fields when its effectiveness is verified.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.65-67
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• 2011

It is necessary to the development of the best maintenance system for applying the long-term maintenance plan using the cost breakdown structure in the educational facilities. This study developed the cost breakdown structure for the best maintenance system using the delphi method. For the convenience of maintenance, the maintenance cost breakdown structures are separated into building exterior wall, building inside wall, electric installation, heating installation and outdoor facilities. And these results atomized in each parts. And this study constructed the cost breakdown structure to maintenance's practicality and effectiveness through the expert analysis.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1655-1660
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• 2009

At the Rolling-stock, most important thing is thorough maintenance for safety as a mass transit. Recently, many studies of cost down method and acquisition of high reliability have being progressed with considering of safety. Maintenance cost is closely relative to the preventive maintenance. But generally the preventive maintenance is decided in compliance with an experience. So the study of cost down method at the preventive maintenance is difficult. In this study, many results of effectiveness and optimization for the preventive maintenance are checked. Then., it is possible that efficiency preventive maintenance method will be able to suggest.