• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.12
• /
• pp.1717-1722
• /
• 2018

Parts and units of 8200 series electric locomotive are aging, but and source technology is not secured. As a results, maintenance costs are increasing steadily due to using expensive substitute parts. Therefore, various studies have been conducted to reduce maintenance costs. In this paper, the life cycle cost(LCC) of the developed and conventional products were compared and analyzed about main conversion system in 8200 Series electric locomotive. As a result of analysis, the material cost was the highest in the conventional product among the various item costs. On the other hand, it is confirmed that preventive cost was the highest among the costs about the developed product.

• Quality Improvement in Health Care
• /
• v.23 no.1
• /
• pp.25-38
• /
• 2017

Root cause analysis (RCA) is systematic process for identifying contributing factors and root causes. It detects system-level vulnerabilities and prevents them from occurring in the future. In many countries, RCA guidelines have been developed and used for these purposes, and various practical tools are suggested according to stages of RCA implementation. In Korea, adverse events occur in 7.2-8.3 percent of inpatients according to studies conducted in hospitals. However, frontline staffs are suffering from lack of knowledge about RCA implementation. This study introduces RCA guidelines that may be used in hospitals to improve the quality of medical care and patient safety.

• 대한예방의학회:학술대회논문집
• /
• 2005.10a
• /
• pp.365-365
• /
• 2005

• Journal of Korean Society for Quality Management
• /
• v.41 no.4
• /
• pp.693-708
• /
• 2013

Purpose: This study is to develop an evaluation model for analysis of CMMS Implementation status and provide CMMS advancement methods to maximize implementation effect through the evaluation model. Methods: After extracting common modules from CMMS packages and establishing evaluation standard for each module, then the evaluation standard is applied to 33 Korean companies for evaluating their own current implementation status. Results: Preventive maintenance and analysis information modules were considered the most vulnerable in Korean companies which have introduced CMMS packages. And the reason why preventive maintenance is vulnerable is that there is poor build-up of their own preventive maintenance standards. Conclusion: Korean companies which will introduce CMMS need to make preventive maintenance standards, and data of the materials and the equipment to improve the effectiveness in advance.

• 대한예방의학회:학술대회논문집
• /
• 2002.10a
• /
• pp.530-531
• /
• 2002

• International Journal of Reliability and Applications
• /
• v.1 no.1
• /
• pp.15-26
• /
• 2000

This paper considers an aperiodic preventive maintenance (PM) model for repairable systems, in which the time intervals between two consecutive preventive maintenances are unequal. To propose such an aperiodic PM model, we assume that each PM reduces the current hazard rate by a certain amount which depends on the number of PMs performed previously. If the system fails between PMs, the minimal repair is performed and the hazard rate remains unchanged after the repair. We give the exact expressions for the hazard rate function for the aperiodic PM model. Based on the proposed aperiodic PM model, we suggest the maximum likelihood method to estimate the parameters characterizing the model and apply the method to the case of Weibull distribution. Numerical examples for estimating the parameters are presented for the purpose of illustration.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.2
• /
• pp.248-253
• /
• 2007

Traditional time based preventive maintenance is used to constant maintenance interval for equipment life. In order to consider economic aspect for time based preventive maintenance, preventive maintenance is scheduled by RCM(Reliability-Centered Maintenance) evaluation. So, Markov state model is utilized considering stochastic state in RCM. In this paper, a Markov state model which can be used for scheduling and optimization of maintenance is presented. The deterioration process of system condition is modeled by a Markov model. In case study, simulation results about RCM are used to the real historical data of combustion turbine generating units in Korean power systems.

• Journal of Applied Reliability
• /
• v.1 no.1
• /
• pp.47-54
• /
• 2001

This paper considers the parameter estimation problem of the failure intensity function and maintenance effect in a repairable system. We propose estimation procedures for repairable systems on which preventive maintenance is performed. The failure process is modeled by a proportional age reduction model [Brown, Mahoney and Sivazlian(1983)] which is useful to model the imperfect effect of preventive maintenance. When failure and maintenance (preventive) times are given, the maximum likelihood method is used to estimate the maintenance effect and the parameters of intensity function, simultaneously We obtain the maximum likelihood estimators using a genetic algorithm. A numerical example is also presented.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.21 no.46
• /
• pp.229-240
• /
• 1998

In these days, we are facing the needs of the times that the product have to be converted from quantity to quality. Most companys now pay more attention to maximize efficiency of facilities with introducing high priced equipments, those equipments are too automated and electronic that partial failure or short time stop leads to the stop of producing process in the whole factory. Consequently, effective maintenance management of production equipment becomes a only solution against problems. This thesis develops a preventive maintenance software that grasp a failure sign through daily inspection with management item, Machine-Capability index and estimate a trend, determine the time of preventive maintenance. The software is useful to the plant operator in analyzing information easily and controlling preventive maintenance operations efficiently.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.10 no.16
• /
• pp.75-80
• /
• 1987

This paper is deals with the preventive replacement for the equipment which fails only when the total amount of damage reaches a prespecified failure level. Most of replacement model use time as their decision variable, but it is not appropriate for the cases in which failures dependent on their cumulative damage levels. In this paper, a new type preventive replacement model is introduced in which an equipment is replaced before failure when the cumulative damage reaches a certain level or replaced on failure, whichever occures first. The optimal replacement damage levels which minimize total expected cost are obtained by the Dynamic programming Method when the number of use of the equipment is finite. A numerical example is also presented. The optimal preventive replacement policy when the equipment will be used for a finite time span is also discussed.