• International Journal of Railway
• /
• v.1 no.3
• /
• pp.94-98
• /
• 2008

Static inverters are essential devices onboard of rolling stock. State-of-the-art static inverters have an impact on both rail infrastructure and vehicle maintenance due to their new topology with new features. The paper describes two important aspects as examples of new features available in state-of-the-art static inverters: active input current control and the effects on the rail infrastructure as well as the detection of the state of charge and the state of health of batteries to simplify vehicle maintenance.

• Advances in aircraft and spacecraft science
• /
• v.2 no.4
• /
• pp.391-401
• /
• 2015

Crashworthiness design and certification have been and will continue to be the main concern in aviation safety. The effects of roll angles on fuselage section crashworthiness for typical civil transport category aircrafts were investigated. A fuselage section with waved-plates under cargo floor is suggested, and the finite element model of fuselage section is developed to simulate drop test subjected to 7 m/s impact velocity under conditions of 0-deg, 5-deg, 10-deg and 15-deg roll angles, respectively. A comparative analysis of failure modes, acceleration responses, and energy absorption of fuselage section under various conditions are given. The results show that the change of roll angles will significantly affect fuselage deformation, seat peak overloads, and energy absorption. The crashworthiness capability of aircraft can be effectively improved by choosing appropriate landing way.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.711-712
• /
• 2011

• Journal of Korean Institute of Industrial Engineers
• /
• v.36 no.2
• /
• pp.108-116
• /
• 2010

The maintenance of a deteriorating system is often imperfect. Previous studies have shown that the imperfect preventive maintenance (PM) can reduce the wear out and aging effects of deteriorating systems to a certain level between the conditions of as good as new and as bad as old. In this paper, we employ the concept of the improvement factor in investigating two optimal PM policies; failure limit policy and periodic PM policy. We redefine the improvement factor model as a function of the cost of PM, using this concept, we derive the conditions of optimal PM policies and formulate expressions to compute the expected cost rate. Based on this information, the determination of the maintenance policies which minimize the cost rate is examined. Numerical examples for the Weibull distribution case are also given.

• Proceedings of the KSR Conference
• /
• 2003.10b
• /
• pp.454-459
• /
• 2003

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 reviewed ECOTRACK system and present the plan of develope decision-making support system for track maintenance appropriate to local condition.

• Journal of the Korea Safety Management & Science
• /
• v.19 no.3
• /
• pp.49-58
• /
• 2017

This paper suggests a specific model that could efficiently improve the interaction and the interface between MES(Manufacturing Execution System) server and POP(Point of Production) terminal through electronic document server and electronic pen, bluetooth receiver and form paper in disassembly and process inspection works. The proposed model shows that the new method by electronic document automation system can more efficiently perform to reduce processing time for maintenance work, compared with the current approach by handwritten processing system. It is noted in case of the method by electronic document automation system that the effects of proposed model are as follows; (a) While the processing time per equipment for maintenance by the current method was 300 minutes, the processing time by the new method was 50 minutes. (b) While the processing error ratio by the current method was 20%, the error ratio by the new method was 1%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.1
• /
• pp.58-65
• /
• 2008

Reliability-Centered Maintenance plan for maintenance schedule of generating unit is being assessed in this paper. Maintenance schedule is a key index that can be used to determine stability and cost. In this paper, stochastic FMECA is described for the life assessment by using probability distribution, and combustion-turbine generations in Korean power systems have been assessed for maintenance schedule. Such an assessment can be a useful guide for maintenance plans in restructured power industry.

• Structural Monitoring and Maintenance
• /
• v.10 no.1
• /
• pp.25-42
• /
• 2023

Despite the significance of ports as critical economic infrastructure, the berth facilities usually deteriorate due to heavy loading, unloading, aging, environmental weather conditions, marine growths, and lack of efficient maintenance management. Marine berths require proactive maintenance management to limit deterioration and defects as no berth facility is maintenance-free. Thus, delay in carrying out maintenance work for the marine berths can be devastating to the operational process involving ship entry, loading, and unloading operations. The aim of this research is to coordinate both operations work, and maintenance works that take place inside the berth of a local industrial port in Saudi Arabia, by developing a novel framework that integrates both works without affecting the efficiency and functionality of the berth. The study focused on defining the operational process of the port and identifying the elements with direct and indirect effects. In addition to determining the priority for the entry of ships inside the berth, it also identified the factors involved in designing a framework that included maintenance work as a component of the monthly berth occupancy schedule. By applying a mathematical model, a framework was established, which includes all the important elements of the process. As a result of the mathematical method formulation process, a database was designed that organizes and coordinates the operations of all berths within the port. This creates time to carry out the required maintenance work monthly as well as ease of coordination with the contractors responsible for the implementation of those works.

• Journal of Advanced Navigation Technology
• /
• v.28 no.4
• /
• pp.524-531
• /
• 2024

In a global environment, airlines are striving to secure competitiveness and generate profits through customer satisfaction. The first thing to do in order to provide services to customers is the safety of the aircraft, and the basis for realizing safety is the continuous maintenance of maintenance quality. The degree of development of aviation technology is progressing unimaginably fast, but the overall environment of aviation mechanics working at the front line to maintain maintenance quality remains largely unchanged. This study aims to identify the level of education and training provided to aircraft maintenance engineers and safety culture, and to examine the effect of self-esteem on maintenance quality. Previous studies have been conducted on maintenance engineers' education and training, organizational performance, and job stress, but there has been a lack of studies on maintenance quality. Therefore, this study aims to identify the relationship between variables affecting maintenance quality and to suggest implications for improving maintenance quality through empirical analysis.

• The Journal of Korean Physical Therapy
• /
• v.21 no.4
• /
• pp.89-96
• /
• 2009

Purpose: This study examined the effects of manual lymph drainage (MLD) on edema and the quality of life (QOL) of lymphedema patients in the maintenance phase. Method: Forty five lymphedema patients, who had completed intensive decongestive therapy, were enrolled in this study. All subjects were assigned randomly to two groups: Experimental (MLD) group (n=23) and control (self-MLD) group (n=22). MLD by a specialist was applied with a comfortable pressure for 40~60 minutes in the experimental group and self-MLD was carried out by the control group 5 times a week for 2 weeks. The % edema and a SF-36 questionnaire were used to measure the decrease in edema and the QOL. A paired t-test was used to compare the period, and an independent T-test was used to compare experiment and control groups. Result: The % edema was significantly lower in the experimental group after MLD (p<0.05). The physical, vitality, and mental health scores of the experimental group was significantly higher than those of the control group (p<0.05). Conclusion: TMLD by a specialist in the maintenance phase is effective in reducing the % edema and enhancing the QOL of lymphedema patients. Further studies will be needed to determine if there are differences in the effects of many types of treatment methods in the lymphedema treatment.