• The Korean Journal of Ecology
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• 제25권1호
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• pp.19-24
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• 2002

The traditional Japanese agricultural landscape, In which a set of varied land-use patches functions as a sustainable ecosystem landscape unit, not only provides the local people tilth a stable food supply, but also offers a variety of habitats to many species of wildlife. Therefore, remaining natural habitats including those in the traditional agricultural landscape should be maintained whenever possible. In addition, restoration work should be implemented in areas where the natural habitat has been destroyed or severely degraded by human activities. This basic approach to the natural environment is a combination of maintenance and restoration. Types of maintenance and restoration can be classified into three categories according to the countermeasures employed: preservation, conservation and protection types of maintenance, and improvement, reconstruction and creation types of restoration. Four steps are proposed for ecological restoration and maintenance of a target area: exploration, diagnosis, prescription and care. In this process, a model for approaching the goal is important. One of the most important models should center on the traditional agricultural landscape involving a sustainable farming ecosystem. It is necessary to protect traditional landscapes and ecosystems from the degrading impact of urbanization and industrialization, as well as to enhance efforts at restoration.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1158-1164
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• 2007

Recently, the demand on the practical application of life-cycle cost effectiveness for design and rehabilitation of civil infrastructure is rapidly growing unprecedentedly in civil engineering practice. Accordingly, it is expected that the life-cycle cost in the 21st century will become a new paradigm for all engineering decision problems in practice. However, in spite of impressive progress in the researches on the LCC, so far, most researches in Koreahave only focused on roadway bridges, which are not applicable to railway bridges. Thus, this paper presents the formulation models and methods for uncertainty-based LCCA for railroad bridges consideringboth objective statistical data available in the agency database of railroad bridges management and subjective data obtained form interviews with experts of the railway agency, which are used to anew uncertainty-based expected maintenance/repair costs including lifetime indirect costs. For reliable assessment of the life-cycle maintenance/repair costs, statistical analysis considering maintenance history data and survey data including the subjective judgments of railway experts on maintenance/management of railroad bridges, are performed to categorize critical maintenance items and associated expected costs and uncertainty-based deterioration models are developed. Finally, the formulation for simulation-based LCC analysis of railway bridges with uncertainty-based deterioration models are applied to the design-decision problem, which is to select an optimal bridge type having minimum Life-Cycle cost among various railway bridges types such as steel plate girder bridge, and prestressed concrete girder bridge in the basic design phase.

• 한국전자거래학회:학술대회논문집
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• 한국전자거래학회 2003년도 종합학술대회 논문집
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• pp.72-77
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• 2003

시설물의 손상현황을 파악하기 위한 현장점검업무는 의사결정과 유지보수공사를 위한 원천 정보를 생성하는 과정으로서 시설물 유지관리 Life Cycle에서 매우 중요한 부분을 차지하고 있다. 하지만, 수작업 및 중복입력 둥의 과다한 업무와 손상상태의 결정, 점검이력의 활용미비, 유지관리업무의 전문성 부족 등으로 효율성과 신뢰성을 갖춘 점검업무가 수행되지 못하고 있는 실정이다. 본 연구에서는 국도 상의 주요구조물인 교량, 터널, 지하차도 등을 대상으로 과다한 현장점검업무를 효율적으로 처리하고 점검결과에 신뢰성을 제공할 수 있는 현장점검시스템을 개발하였다. 현장점검업무의 분석과정에서 나타나는 문제점들을 파악하여 개선방안을 기능설계에서 반영하여 시스템화하였다. 본 시스템은 국도유지건설사무소에서 활용할 애정이며, 손상상태의 추적, 보수 물량 산출 등 유지관리 업무의 효율적인 관리가 가능해질 것으로 기대된다.

• 교육시설 논문지
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• 제25권1호
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• pp.3-12
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• 2018

Educational facilities are more uncertain about maintenance costs due to their comprehensive and long life-cycle compared to commercial buildings. In addition, maintenance of the existing post management system can not maintain the original function of education facilities continuously and economically. In order to overcome this problem, it is necessary to analyze the repair and replacement cost for the uncertainty factor in maintenance. This study propose a model to determine repair and maintenance cost and cycle of educational facility based on probabilistic estimation concept. For the analysis, Monte Carlo simulation, a probabilistic analysis method, was applied based on the repair and maintenance history data of the educational facilities in Florida. The results of this study can be used as a guideline for quantitative facility management and facility management research.

• Structural Monitoring and Maintenance
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• 제5권4호
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• pp.489-506
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• 2018

This paper reported test of full-scale cables attached with four types of dampers: viscous damper, passive Magneto-Rheological (MR) damper, friction damper and High Damping Rubber (HDR) damper. The logarithmic decrements of the cable with attached dampers were calculated from free vibration time history. The efficiency ratios of the mean damping ratios of the tested four dampers to theoretical maximum damping ratio were derived, which was very important for practical damper design and parameter optimization. Non-ideal factors affecting damper performance were discussed based on the test results. The effects of concentrated mass and negative stiffness were discussed in detail and compared theoretically. Approximate formulations were derived and verified using numerical solutions. The critical values for non-dimensional concentrated mass coefficient and negative stiffness were identified. Efficiency ratios were approximately 0.6, 0.6, and 0.3 for the viscous damper, passive MR damper and HDR damper, respectively. The efficiency ratio for the friction damper was between 0-1.0. The effects of concentrated mass and negative stiffness on cable damping were positive as both could increase damping ratio; the concentrated mass was more effective than negative stiffness for higher vibration modes.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권2호
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• pp.114-121
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• 2018

Purpose: This study proposes a process for evaluating the preventive maintenance policy for a system with degradation characteristics and for calculating the appropriate preventive maintenance cycle using time- and condition-based maintenance. Methods: First, the collected data is divided into the maintenance history lifetime and degradation lifetime, and analysis datasets are extracted through preprocessing. Particle filter algorithm is used to estimate the degradation lifetime from analysis datasets and prior information is obtained using LSE. The suitability and cost of the existing preventive maintenance policy are each evaluated based on the degradation lifetime and by using a minimum repair block replacement model of time-based maintenance. Results: The process is applied to the degradation of the reverse osmosis (RO) membrane in a seawater reverse osmosis (SWRO) plant to evaluate the existing preventive maintenance policy. Conclusion: This method can be used for facilities or systems that undergo degradation, which can be evaluated in terms of cost and time. The method is expected to be used in decision-making for devising the optimal preventive maintenance policy.

• 한국재난정보학회 논문집
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• 제16권2호
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• pp.276-290
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• 2020

연구목적: 국내 항만시설의 건설역사는 100년 이상 되었으며 최근 까지 현대적 시설이 지속적으로 건설되어 확장되고 있다. 그러나, 해양환경의 변화 및 물동량의 증가 등으로 초기 건설당시의 요구 성능조건을 유지하기는 쉽지 않다. 특히, 사용년수가 오래된 항만구조물의 경우, 선박의 대형화와 사용빈도 증가, 자연재해의 규모 증가등으로 안전성능과 기능관리가 매우 중요해져 가고 있다. 연구방법: 이에 본 연구는 항만시설의 구조형식별 상태변화를 조사하고 이를 기반으로 성능개선 및 수명연장활동에 기여하는 보수보강활동과 그 이력을 분석하였다. 연구결과: 항만시설 유지관리전략수립에 활용 가능한 성능개선비용(CAPEX)과 수선유지활동(OPEX)을 구별하고 이를 통한 유지관리전략수립에 활용 가능한 비용모델을 제시하였다. 결론: 이러한연구는 향후 시설물 중장기 투자의사결정에 큰 기여를 할 것으로 기대된다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.719-726
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• 2005

The optimal design was performed for the bridge superstructure composed of steel box girders and concrete deck considering life cycle cost. The service life of the superstructure was estimated, after load carry capacity curves for steel girder and concrete deck were derived on the basis of condition grade curves and maintenance histories. The object function was determined as life cycle cost, including initial cost, total maintenance cost, disposal cost and user cost, for a period of the estimated service life. The optimal design of the superstructure was performed for the various service lifes. The annual costs were used to compare calculated results and to get the most economical design. Also this paper presents reasonable idea for the use of user cost with uncertainty.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.259-264
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• 2003

Failure code system must include data of maintenance history, classification of failure, affective range and situation when failure occur. But the present failure code system have used a simple code system for classification to include only merchandise and tools. Advantageously, expansional standard code system that will be developed, it make that users can take steps of standardized overhaul and inspection as proposal maintain contents when failure occur or something wrong in vehicle of urban transit. Standardized failure codes must be developed and used that manufacturing companies and urban transit operating companies in order to give effect to maintenance works.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1014-1023
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• 2008

The K-AGT test line is managed similarly to revenue operation and operated automatically 120km per day, total 90,000km from August 2004 to December 2007. To enhance reliability of developed system, maintenance information system based on RCM is applied. The maintenance program applied in test line is based on RCM which prevent a fault before it happens and a fault made in test line is analysed by reliability growth test. Vehicle system, power supply system, signalling system, track and infrastructure are built in test line and it is reviewed enhancing system performance and changing designs to commercialize through reliability growth analysis method.