• Title, Summary, Keyword: low-maintenance

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A study on Propulsion Fuel consumption rate for orbit maintenance of LEO

  • 정도희;공창덕
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.10-10
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    • 2000
  • For low Earth orbit, the atmosphere causes orbit altitude to decrease, If this decrease is not corrected by the satellite propulsive unit, the orbit decoys continuously unit reaches the dense atmosphere and satellite life ends. If active orbit maintenance is mode by satellite propulsive unit then fuel consumption is necessary, which must be considered in the satellite design. Especially interesting is the method for evaluating the fuel consumption role for maintenance of elliptical orbit developed in this paper.(omitted)

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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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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.

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.

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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A Study on Value Orientation of Health of Rural Health Center Milieu (농촌지역 보건소 환경에 있어서의 건강가치관에 관한 일 조사연구)

  • 김순자
    • Journal of Korean Academy of Nursing
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    • v.5 no.1
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    • pp.17-30
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    • 1975
  • The concept and definition of nursing and her role have been changing in accordance with the socio-cultural factors of the initial society. At present, nursing is conceptualized as a health care profession assisting man to restore, maintain and promote health by providing knowledge, wilt strength and resources through various processes of interaction. Man′s behavior, of individual and group activities for health inclusive, is driven by the initial man′s value orientation. The purpose of this study is to investigate the value orientation regarding health of rural health center milieu in order to give data for; 1. the planning for the delivery of community nursing service, 2. the health education plan at all level of nursing care activities, and 3. the planning of curriculum for nursing education. A hundred opinion leaders among the labor population residing in rural areas (P-group), hundred and six professional nurses at rural health centers (N-group) were indirectly interviewed through questionaries. And ninety five of N-group were interviewed likewise of their perceptions of P-group (NP-group) from July 15, to October 15, 1974. The result is as follows: 1. Maintenance of health is revealed to be the most valued component for man′s happiness in all the three groups. (P-group: 7.30 S. D.=1.31), (N-group :7.84 S. D. =49), and (NP-group : 5.93 S. D. =2.28) 2. The average value score of the maintenance of health revealed significant difference by P〈.001 level between each of the three groups. (Between N-group and P-group : T= -4.07 P and NP ; T=-6.93, N and NP: T=-9.35) 3. Basic health maintenance activities necessary for maintenance and promotion of personal health were moderately valued by all the three groups, P-group ; 3.74 (S. D. =.43) , N-group: 3.52 (S. D. =.34), NP-group: 3.07 (S. D. :.55) Among the 8 categories of basic health maintenance activities, "food intake" was highly valued by P-group (mean value score; 4.00 S. D=.51) , "exercise and rest" and "personal cleanliness" was highly valued by both P-group (4.02, 4.08) and N-group (4.08, 4.22). 4. The mean value score of basic health maintenance activities revealed significant difference by P〈.001 level between each of the three groups (between P-group and N-group: T=-4, 07, N-and NP: T=-6.93, P and NP T=-9.35) 5. Among the 30 questionaries, dynamic activities for health maintenance were more valued in comparison to passive activities in an tile three groups. 6. In N-group, correlation between the value of basic health maintenance activities and the personal health status personal revealed moderate significance. Correlation between the value of basic health maintenance activities and the age revealed low significance. 7. In group, correlation between the value of basic health maintenance activities and; perception of personal health status revealed non significance, between the age and sex revealed low sign affiance, and between the educational status revealed moderate significance. Recommendations are as follows ; 1. The efforts towards alteration of value orientation concerning health in general in community nursing practice de focussed be that of family Planning. 2. In order to prepare professional nurses competent in understanding individual and group, social science and behavioral science be strength ended in planning nursing curriculum. 3. Milieu of nursing experience during nursing education be Planned to begin at simple nursing problem and move towards complex, f. e. home care towards health crisis situation in order to achieve dynamic role mastery.

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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.

Derivation of Sustainability Factors of LID Facility and Strategy of Citizen Participation for Management (LID 시설의 지속가능성 관리인자 도출 및 시민참여 관리방안)

  • Kim, Youngman;Kim, Lee-hyung
    • Journal of Wetlands Research
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    • v.21 no.1
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    • pp.57-65
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    • 2019
  • LID(Low Impact Development) facility classified as a social infrastructure can maintain landscape sustainability and functional sustainability through continuous maintenance and management. Since LID is a natural-based solution, the sustainability can be secured through the management of weeds, wastes and vegetation. The LID facility is distributed in the city and is an infrastructure that can be managed through citizen participation because of simple maintenance. Therefore, this study was conducted to investigate the maintenance factors affecting the sustainability of the LID facilities and to suggest measures for maintenance by investigating the participation of the peoples. The factors for landscape sustainability were derived to waste and weed management. Also the factors for functional sustainability were assessed to identification and management of dead bodies and selection of applicable soil and plant species. The citizens showed high agreement of more than 80% in the questionnaires on expanding and managing LID facilities, enacting LID ordinances, and participating in the national movement. The intention to participate in LID management linked to jobs was about 64%, indicating that LID could become a job for the vulnerable. Maintenance of the LID can easily be carried out by non-specialists, which can lead to citizen participation with low cost for each facility. The maintenance cost for citizen participation can be allocated from the social infrastructure management cost reduced by LID application of the local government and the social welfare budget of the central government.