• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1331-1338
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• 2010

Recently, the need for improving the economical efficiency of pumped-storage power plants has increased because of the decrease in the availability of electricity caused by an increase in the consumption of electricity at night. Therefore, a preventative maintenance cycle, especially an overhaul cycle, is required. Unconditional extension cannot be implemented because it may cause unanticipated failures due to insufficient maintenance. Therefore, in this study, a methodology for optimizing the preventative maintenance cycle by taking into account both reliability and economical efficiency is presented; this methodology has been developed by reviewing previous studies on reliability and considering the characteristics of pumped-storage power plants. Finally, an extended overhaul cycle is derived by applying this methodology to a domestic pumped-storage power plant.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.150-155
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• 2000

우리나라의 공업현대화는 1960년대 초의 경제개발계획으로부터 시작되었으며, 그 당시 우리의 현실은 인천제철과 충주비료공장을 제외하고는 장치 산업이라는 대형산업시설이 거의 없었다. 그 후 경제개발의 박차를 가하면서 울산공업단지와 항만$\cdot$배후 시설등의 건설에 힘입어 1970년 초부터 현대적 공업국으로 진입하게 되었다. (중략)

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.2 no.4
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• pp.271-273
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• 1973

에너지 사용의 최적화는 건축설비계통의 각 관점을 다른 모든 사항들과 비교고찰하는 (설치비에 대응하는 장기운전 및 정비의 요구사을 고려하는) HVAC계통설계로부터 얻어 진다. 저자는 최상목표인 쾌적과 경제성을 고려해서 전반적으로 각 분야를 집약한 계통설계의 프로그램을 제시하고 있다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.43-50
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• 2010

In this paper, the TWTA (Traveling Wave Tube Amplifier) maintenance system for the low altitude surveillance Radar was developed using the embedded Linux system, and its superiority was demonstrated through the performance test. Nowadays, the necessity of maintenance system and reliability testing on military equipments has been increasing steadily. In addition, nonlinear characteristics of the maintenance system for the low altitude surveillance Radar are more likely to have serious problems as well as to slow down durability. Therefore, after analyzing characteristics of RF input-output signal and TWTA, we designed interface circuits between the TWTA equipment and the embedded Linux system. The Linux kernel on the system was optimized to improve the efficiency and reliability. And our new TWTA maintenance system was evaluated in the real field. As a result, the proposed system was contented with desired specifications, and demonstrated military's fighting capabilities. Therefore, our novel system will advance military maintenance technology and will help to develop similar equipments.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.446-452
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• 2016

The aircraft has to be considered for safety very importantly because of peculiarity of flight in the air, so it should be retained through proper inspection and maintenance not only in production phase but also in operating phase. Recently, it is using the latest technology as engineering approach not depending on human factor to determine on maintenance needs, and domestic production rotary aircraft also has the health & usage monitoring system to measure and to monitor major components. However, continued vibration exceedance phenomenon occurred in production and operation phase because of inappropriate thresholds, and it confirmed as false alarm which is not necessary to repair. In this paper, it is described that operational concept of HUMS, and especially it contains a study result for efficiency of aircraft operation and ultimately the improvement of flight safety by optimizing HUMS thresholds to determine efficiently necessity of maintenance under limited conditions and by establishing inspection/maintenance procedures when the re-designated thresholds exceedance occurred.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.9-15
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• 2010

When designing the size of a heavy maintenance shop for rolling stock, it is required to arrange buildings and facilities in the minimum site so as to improve the maintenance efficiency. However, the fluctuation rate (hereinafter "allowance rate") on which factors such as service and maintenance fluctuation should be applied when estimating the size of the maintenance shop has been used without verification. The objective of the study is to calculate a reasonable allowance rate and to review its appropriateness through the analysis of the facilities layout and process simulation to absorb the above elements into the staying time in the heavy maintenance shop. Since the working time, in this study, is assumed to be average working time, 10~20% was given to the standard deviation of working time in consideration of difference between workers, and possible allowance rate was drawn by analysis of the simulation results. In the future, it is required to optimize the size of the shop by applying appropriate allowance rate through scientific review of such factors as O&M plan, R/S reserve rate, capability of the shop, outsourcing rate, standard work amount, and so on.

• Journal of the Korean Society for Computer Game
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• v.31 no.4
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• pp.111-119
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• 2018

National agencies and corporations are making a lot of efforts to educate mechanics from high school to university and enterprise training center to train as skilled mechanic. but the theoretical training using textbooks and the training using equipment not used in the field did not provide proper maintenance training. And education using special equipment or assuming dangerous situation was very dangerous, so we were carrying out education with video or photo. In recent, there have been a number of cases in which effective training simulations have been researched and developed in order to experience situations and solve problems safely through simulation from simple maintenance to special maintenance by combining VR and AR. This paper describes the comparative study of the existing APIs such as Danuri VR, DisTi Engine and Remote AR for general purpose AR/VR contents. We also proposed a AR/VR API based on Unity 3D Engine for AR/VR maintenance contents. The API can be used for maintenance contents developers efficiently.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.7-13
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• 2011

Turbine journal bearings are designed to support the weight of the rotors on a hydrodynamic oil film and to provide dynamic stability to the rotor system. The life time of journal bearings is infinite theoretically because the journal bearings are separated from the shaft journal by oil film. But poor design, assembly, operation and maintenance can cause problems to the journal bearings. The FMEA(Failure Mode and Effects Analysis) results of the journal bearings show that frequent maintenance of the journal bearings can cause failures and reduction of the bearing life. Therefore, the maintenance periods and history of the journal bearings with the bearing FMEA results are reviewed in order to establish the optimized maintenance period of the journal bearing for the nuclear power plants. Consequently it is necessary to maintain a best condition of lubrication system, reject time-based maintenance and perform the condition-based maintenance of journal bearings in order to maintain optimum condition of the journal bearing.

• Journal of the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.306-312
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• 2007

This paper presents the optimal design method of the train repair facility based on the simulation analysis. The train is divided into the power car, motorized car and passenger car for the simulation process analysis and train repair facility is composed of each subsystems such as a blast, dry and wash workshop. In simulation analysis, we consider the critical (dependent) factors and design (independent) factors for the optimal design. Therefore, a simulation optimization uses Evolution Strategy (ES) in order to find the optimal design factors. Experimental results indicate that simulation design factors are sufficient to satisfy the conditions of dependent variables. The proposed analysis method demonstrates that simulation design factors determined by the simulation optimization are appropriate for real design factors in a real situation and the accuracy and confidence for the simulation results are increased.

• Journal of the Korea Society for Simulation
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• v.21 no.3
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• pp.79-88
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• 2012

Recently, the study in efficient operation, maintenance, and equipment-design have been growing rapidly in military industry to meet the required missions. Through out these studies, the importance of Concurrent Spare Parts(CSP) are emphasized. The CSP, which is critical to the operation and maintenance to enhance the availability, is offered together when a equipment is delivered. Despite its significance, th responsibility for determining the range and depth of CSP are done from administrative decision rather than engineering analysis. The purpose of the paper is to optimize the number of CSP per item using simulation and multiple regression. First, the result, as the change of operational availability, was gained from changing the number of change in simulation model. Second, mathematical regression was computed from the input and output data, and the number of CSP was optimized by multiple regression and linear programming; the constraint condition is the cost for optimization. The advantage of this study is to respond with the transition of constraint condition quickly. The cost per item is consistently altered in the development state of equipment. The speed of analysis, that simulation method is continuously performed whenever constraint condition is repeatedly altered, would be down. Therefore, this study is suitable for real development environment. In the future, the study based on the above concept improves the accuracy of optimization by the technical progress of multiple regression.