• Title, Summary, Keyword: low-maintenance

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Analysis to be used for the Life Cycle Costs calculation of rolling stocks for EMU (EMU 철도차량의 LCC(Life Cycle Cost)분석)

  • Park, Su-Myung
    • Proceedings of the KSR Conference
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    • pp.177-183
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    • 2009
  • This paper deals with the topical problems of the Life Cycle Costs in connection with the rolling stocks. the LCC philosophy has already entered the third decade. this philosophy contributed towards the new relationship's comprehension between railway vehicle producers' and railway vehicle users' sphere. this leads together to the technical-economical solution convenient for the both sides. In the point of manufacturer, It is said that low operational costs could be reached using a well-designed and structured maintenance program. this is due to the proper technical analysis of critical components that leads to low costs of maintenance and a superior reliability without increasing the capital investment. but, This paper presents both topical experiences with the LCC models for the railways vehicles and also procedures during Life Cycle Costs calculations. In conclusion I want to introduce how to calculate LCC & what kinds of softwares are used based on VVVF EMU vehicle

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GROUND TRACK ACQUISITION AND MAINTENANCE MANEUVER MODELING FOR LOW-EARTH ORBIT SATELLITE

  • Lee, Byoung-Sun;Eun, Jong-Woo;Webb, Charles-E.
    • Journal of Astronomy and Space Sciences
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    • v.14 no.2
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    • pp.355-366
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    • 1997
  • This paper presents a comprehensive analytical approach for determining key maneuver parameters associated with the acquisition and maintenance of the ground track for a low-earth orbit. A livearized model relating changes in the drift rate of the ground track directly to changes in the orbital semi-major axis is also developed. The effect of terrestrial atmospheric drag on the semi-major axis is also explored, being quantified through an analytical expression for the decay rate as a function of density. The non-singular Lagrange planetary equations, further simplified for nearly circular orbits, provide the desired relationships between the corrective in-plane impulsive velocity increments and the corresponding effects on the orbit elements. The resulting solution strategy offers excellent insight into the dynamics affecting the timing, magnitude, and frequency of these maneuvers. Simulations are executed for the ground track acquisition and maintenance maneuver as a pre-flight planning and analysis.

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On determining a non-periodic preventive maintenance schedule using the failure rate threshold for a repairable system

  • Lee, Juhyun;Park, Jihyun;Ahn, Suneung
    • Smart Structures and Systems
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    • v.22 no.2
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    • pp.151-159
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    • 2018
  • Maintenance activities are regarded as a key part of the repairable deteriorating system because they maintain the equipment in good condition. In practice, many maintenance policies are used in engineering fields to reduce unexpected failures and slow down the deterioration of the system. However, in traditional maintenance policies, maintenance activities have often been assumed to be performed at the same time interval, which may result in higher operational costs and more system failures. Thus, this study presents two non-periodic preventive maintenance (PM) policies for repairable deteriorating systems, employing the failure rate of the system as a conditional variable. In the proposed PM models, the failure rate of the system was restored via the failure rate reduction factors after imperfect PM activities. Operational costs were also considered, which increased along with the operating time of the system and the frequency of PM activities to reflect the deterioration process of the system. A numerical example was provided to illustrate the proposed PM policy. The results showed that PM activities performed at a low failure rate threshold slowed down the degradation of the system and thus extended the system lifetime. Moreover, when the operational cost was considered in the proposed maintenance scheme, the system replacement was more cost-effective than frequent PM activities in the severely degraded system.

Structural Performance of Retrofitted Reinforced Concrete Walls (보강된 철근콘크리트 벽체의 구조적 성능)

  • Shin, Yeong-Soo;Hong, Gi-Suop
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.2 no.3
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    • pp.212-222
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    • 1998
  • In several structural problems, the low concrete strength of compression members has the severest influence on the structural safety. However, the repairing and strengthening techniques for compression members are not established and evaluated. This study aimed to develop and evaluate the rehabilitation techniques to obtain proper structural strength of wall with low concrete strength. The specimens with low strength of concrete were retrofitted with commonly using section increase method and epoxy bonded glass fiber techniques. The tests were executed to failure under concentric and eccentric loads. In this paper, the structural behavior and failure modes were investigated to evaluate the strengthening effects of walls subjected to compression and out-of-plane bending.

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Evaluation on Vibration Characteristics of an Apartment Building Structure (아파트 구조물의 진동특성 평가에 관한 연구)

  • Choi, Chang-Sik;Lee, Li-Hyung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.2 no.3
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    • pp.161-167
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    • 1998
  • A problem of frequency in the field of low-frequencies such as high-rise apartment building or construction vibration are often found. In this study, damage reason of a 25 stories apartment building was searched on the basis of actual damage. To find the damage reason, structural design procedure were reviewed and low-frequency vibration test was conducted. The results indicate that the main damage reason is not by the low-frequency vibration but the asymmetrical plan of that building.

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Control system modeling of stock management for civil infrastructure

  • Abe, Masato
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.609-625
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    • 2015
  • Management of infrastructure stock is essential in sustainability of society, and its analysis and optimization are studied in the light of control system modeling in this paper. At the first part of the paper, cost of stock management is analyzed based on macroscopic statistics on infrastructure stock and economical growth. Stock management burden relative to economy is observed to become larger at low economic growth periods in developed economies. Then, control system modeling of stock management is introduced and by augmenting maintenance actions as control input, dynamic behavior of stock is simulated and compared with existing time history statistics. Assuming steady state conditions, applicability of the model to cross sectional data is also demonstrated. The proposed model is enhanced so that both preventive and corrective maintenance can be included as system inputs, i.e., feedforward and feedback control inputs. Optimal management strategy to achieve specified deteriorated stock level with minimal cost, expressed in terms of preventive and corrective maintenance actions, is derived based on estimated parameter values for corrosion of steel bridges. Relative cost effectiveness of preventive maintenance is shown when target deteriorated stock level is lower.

Performance Evaluation of SSD-Index Maintenance Schemes in IR Applications

  • Jin, Du-Seok;Jung, Hoe-Kyung
    • Journal of information and communication convergence engineering
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    • v.8 no.4
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    • pp.377-382
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    • 2010
  • With the advent of flash memory based new storage device (SSD), there is considerable interest within the computer industry in using flash memory based storage devices for many different types of application. The dynamic index structure of large text collections has been a primary issue in the Information Retrieval Applications among them. Previous studies have proven the three approaches to be effective: In- Place, merge-based index structure and a combination of both. The above-mentioned strategies have been researched with the traditional storage device (HDD) which has a constraint on how keep the contiguity of dynamic data. However, in case of the new storage device, we don' have any constraint contiguity problems due to its low access latency time. But, although the new storage device has superiority such as low access latency and improved I/O throughput speeds, it is still not well suited for traditional dynamic index structures because of the poor random write throughput in practical systems. Therefore, using the experimental performance evaluation of various index maintenance schemes on the new storage device, we propose an efficient index structure for new storage device that improves significantly the index maintenance speed without degradation of query performance.

Perceived Benefits and Barriers According to the Stage of Mammography Adoption in Adult Women (성인 여성의 유방조영술 검진 참여 단계에 따른 이익요인과 장애요인 분석)

  • Hur, Hea Kung;Song, Hee-Young
    • Korean Journal of Adult Nursing
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    • v.17 no.3
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    • pp.474-483
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    • 2005
  • Purpose: This descriptive study was undertaken to explore the distribution of stages of mammography adoption and identify benefits and barriers perceived by women according to the stage of mammography adoption. Methods: A total of 227 women aged between 30 - 60 was selected by the convenient sampling in W city. The instrument developed by the researcher based on the scales of Champion(1993), Champion & Skinner(2003), and Rakowski et al (1992) was used. Results: The distribution of stages of mammography adoption was as following; precontemplation 30.7%, contemplation 23.8%, relapse 20.2%, action 14.4%, and maintenance 10.8%. Women in maintenance and actors showed high scores in benefits and low scores in barriers. Those in relapse reported high scores in both benefits and barriers, while precontemplators and contemplators showed high score in barriers and low scores in benefits. Conclusion: Despite the rate of mammography participation has increased, the proportion of maintenance stage is still low and that of relapse is high. For those in relapse, strategies to eliminate barriers hindering regular and continuous mammography are necessary. For precontemplators and contemplators, detail information including purpose, procedure and benefits of mammography should be given primarily.

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Bluetooth Low-Energy Current Sensor Compensated Using Piecewise Linear Model

  • Shin, Jung-Won
    • Journal of Sensor Science and Technology
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    • v.29 no.5
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    • pp.283-292
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    • 2020
  • Current sensors that use a Hall element and Hall IC to measure the magnetic fields generated in steel silicon core gaps do not distinguish between direct and alternating currents. Thus, they are primarily used to measure direct current (DC) in industrial equipment. Although such sensors can measure the DC when installed in expensive equipment, ascertaining problems becomes difficult if the equipment is set up in an unexposed space. The control box is only opened during scheduled maintenance or when anomalies occur. Therefore, in this paper, a method is proposed for facilitating the safety management and maintenance of equipment when necessary, instead of waiting for anomalies or scheduled maintenance. A Bluetooth 4.0 low-energy current-sensor system based on near-field communication is used, which compensates for the nonlinearity of the current-sensor output signal using a piecewise linear model. The sensor is controlled using its generic attribute profile. Sensor nodes and cell phones used to check the signals obtained from the sensor at 50-A input currents showed an accuracy of ±1%, exhibiting linearity in all communications within the range of 0 to 50 A, with a stable output voltage for each communication segment.

The Development of Maintenance Process in Long-Life Housing (장수명 공동주택 유지관리를 위한 프로세스 구축에 대한 연구)

  • Ji, Jang-Hun;Kim, Soo-Am;Yoon, Sang-Cho
    • Journal of the Korean housing association
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    • v.21 no.3
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    • pp.115-124
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    • 2010
  • The environment which has been destroyed for the national growth since 1960's would seem to offer infinite resources to human, but now, the existence of human being is threatened by the development thoughtless for the environment. The World Powers have concentrated on green growth with eco-friendly resource since the end of 20th century. Korea suggested that the vision was the low carbon for green growth in 2008. It is necessary to supply Long-Life Housing in the green technology in terms of the sustainable housing development based on various life style, life cycle of the residences, the restrain remodeling and redevelopment in construction. This study is aim to establish the development of maintenance process to make continuous inhabitation of Long-Life Housing that has the separated SI for maintenance, durability, variability and remodeling. The maintenance for Long-Life Housing is very important to have more than 50~70 years the long term of life cycle in comparison with Housing. Also, the roles of manager and user are important parts in Long-Life Housing. The present maintenance for Housing is shift and repair works by the routine maintenance and demage. However, The maintenance for Long-Life Housing should consider movement and flexibility. In addition, Long-Life Housing requires the proper process of maintenance because it is different from Housing in housing concept, design and constructions stage. Therefore this study shows the efficient maintenance process for Long-Life Housing.