• Smart Structures and Systems
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• 제30권6호
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• pp.571-582
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• 2022

Optimal life-cycle management is a challenging issue for deteriorating regional bridges. Due to the complexity of regional bridge structural conditions and a large number of inspection and maintenance actions, decision-makers generally choose traditional passive management strategies. They are less efficiency and cost-effectiveness. This paper suggests a deep reinforcement learning framework employing double-deep Q-networks (DDQNs) to improve the life-cycle management of deteriorating regional bridges to tackle these problems. It could produce optimal maintenance plans considering restrictions to maximize maintenance cost-effectiveness to the greatest extent possible. DDQNs method could handle the problem of the overestimation of Q-values in the Nature DQNs. This study also identifies regional bridge deterioration characteristics and the consequence of scheduled maintenance from years of inspection data. To validate the proposed method, a case study containing hundreds of bridges is used to develop optimal life-cycle management strategies. The optimization solutions recommend fewer replacement actions and prefer preventative repair actions when bridges are damaged or are expected to be damaged. By employing the optimal life-cycle regional maintenance strategies, the conditions of bridges can be controlled to a good level. Compared to the nature DQNs, DDQNs offer an optimized scheme containing fewer low-condition bridges and a more costeffective life-cycle management plan.

• 한국환경복원기술학회지
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• 제22권5호
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• pp.69-79
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• 2019

The purpose of this study is to suggest a guideline that can be used as a standard for consultation and review by environmental impact assessment consultation and review practitioner to enhance the practical effectiveness of creating alternative habitats. The consultation stage of environmental impact assessment was significantly divided into 1) preparation of draft environmental impact assessment reports and gathering of consensus thereon, 2) preparation of environmental impact assessment reports and consultation thereon, 3) follow-up survey of environmental impacts(under construction) and 4) follow-up survey of environmental impacts(in operation). And it was suggested that the procedures of creating alternative habitat by each consultation stage were linked in order of 1) planning, 2) designing, 3) construction, and 4) post-monitoring and maintenance. The basic principles were also proposed for each stage of consultation on environmental impact assessment and procedure for the creation of alternate habitats. Then, issues and methods to be reviewed by the consulting agency and review agency of environmental impact assessment were presented in detail. The guideline of this study provides important information not only to environmental impact assessment consultation and review practitioner, but also to developers and environmental impact assessment agents who plan, construct, and manage alternative habitats.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.66-73
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• 2011

With rapid industrialization, electric power consumption has been increasing every year in Korea and in other countries. The provision of additional power stations to produce more electricity is one possible response to this steady increase in consumption. Another alternative is to improve the efficiency of existing stations through timely and effective maintenance works. Since the construction of a new power plant involves a large amount of capital as well as difficulties in the selection of sites, the improvement of existing power stations' efficiencies is often a preferred solution. Therefore, this paper focuses on maintenance project management to address this issue. Among several types of maintenance works, this paper concentrates on planned outage maintenance (POM). This focus arises from the critical impact of POM on other maintenance work, as well as the entire process of electricity production. Unlike other maintenance work, POM is done on the basis of mid and long-term plans. In addition, only POM works are conducted during the outage of all power plants. To evaluate the efficiency of POM works, budget data relating to 164 POM projects between 2001 and 2008 was collected from 7 sites in South Korea. Data envelopment analysis (DEA) was selected as a methodology for evaluation. From this analysis, comparative study was used to determine the categories of projects that had performed well, and those with the most optimized budget structures. Moreover, through discussion with industry, this research develops a feasible proposed method by which to enhance the efficiency of POM projects.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.624-631
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• 2022

Highway Rest Areas are envisioned to provide an accessible space for rest and parking for travelers, especially those driving a long distance. In addition, modern highway Rest Areas provide many amenities to highway users, including wifi service, picnic tables, litter barrels, running water, public telephones, and sometimes even free coffee. Various studies were conducted in the domain of Rest Area facility design and their operating costs in different states; however, limited studies were conducted on the maintenance costs of these facilities. Therefore, this study's main objective is to compute the annual maintenance cost of Rest Areas in the state of Nevada. This study also analyzes the main cost categories of the maintenance works. The raw cost data of Nevada Rest Area maintenance from 1990 to 2012 were collected from the Nevada Department of Transportation (NDOT). Results show that the maintenance cost fluctuated over the study period; the maintenance cost decreased from 1991 to 2004 and then increased until 2012. The primary cost categories of maintenance work are labor, equipment, and material costs. Among these, labor cost was the largest category with 56 percent of the total maintenance cost, followed by equipment cost and material cost. The findings of this study may help NDOT and other transportation agencies plan their budget for future Rest Area maintenance activities.

• 상하수도학회지
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• 제20권6호
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• pp.919-926
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• 2006

In this study, environmental impact assessments of wastewater treatment plant (WWTP), sewerage system, and tailrace were performed using LCA methodology. The life cycle stages were divided into 3 categories; construction stage, maintenance stage and demolition & disposal stage. As a tool of impact assessment, Ecoindicator99 containing fate analysis, exposure & effect analysis and damage analysis, was used. As tile results of WWTP LCA, more than 80% of environmental impact was produced from maintenance stage. On the other hand, most of environmental impact was produced from construction stage in the case of tailrace and sewerage system construction.

• 산업공학
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• 제17권spc호
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• pp.122-130
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• 2004

Since the cost of software maintenance occupies about 50~75% in a general successful organization, the software maintenance plays an important role in software life cycle. In particular, if the managed system needs to be operated in a long term or the system is very large and complex, then the maintenance is especially more important. Software maintenance is defined as software modification activities after customer delivery, such as improvement of performance or functionality, error correction, adaptation to environmental changes, etc. In this paper, software cost estimation models are proposed, that is based on productivity of manpower in maintenance projects. In order to do this, the activities of maintenance are classified into function change, non-function change, user support and application operation. The proposed models are constructed and verified based on the real size and cost information of projects in the real world. The approach in this paper is to discriminate the heterogeneous activities in maintenance projects, and then to calculate the respective cost of each discriminated activity. By using the proposed models, the total cost of maintenance project is summed from the costs of four activities. In addition the number of conflicts between owner and order receiver about the amount of cost will be reduced and the reasonable cost estimation system will be established.

• 농촌계획
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• 제12권1호
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• pp.11-21
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• 2006

The purpose of this study is to verify the result of the previous studies and to clarify the types and activation factors of maintenance activities of the naturally favorable water space through the participation of residents in rural areas, through a further survey of the area proposed as a program in the existing study review and previous study related to the participation of residents. The survey was conducted through the survey of 1,242 households and 1,335 persons intended for Japanese rural areas. The study result is summarized as follows. The types of the maintenance activities in the areas intended for the survey have been classified into 'rural type' and 'combination type' through the analysis results by the references like the comparison analysis, job percentage and main utilization purpose of facilities for each type of maintenance and operation activities. In case of the 'rural type' area, residents were doing maintenance activities centered on the group activities rather than personal maintenance activities. Also, the activities of maintenance & operation group members were more active than non-members, and the water-friendly utilization to the facilities was not directly affecting the maintenance activities of residents. In case of the 'combinational type' area, there was no common characteristic according to each area, and the participation percentage in the maintenance activities was low compared with the 'rural type' area. According to the analysis result based on the participation degree of personal maintenance activities, the repair of facilities as a naturally favorable water space, implementation of projects reflecting the opinions of residents, educational programs conducted in order to motivate the participation of residents, etc. have been analyzed as the factors affecting the activation of maintenance activities of residents. Through the above results, for continuous maintenance activities to be made with residents as a main body in the future, it is necessary to support maintenance groups on an administrative level and procure experts for the production and operation of programs that can increase the participation percentage of residents.

• International Journal of Railway
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• 제2권3호
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• pp.107-112
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• 2009

Research projects of SNCF aim at reducing the costs of infrastructure possessions and improving the operational equipment availability and safety. This permanent search for a better regularity led the SNCF to analyse the maintenance approach of signalling equipment in detail. Until now, it was commonly acknowledged that signalling equipment, which consists of many electronic devices, is not subject to aging. In this study, a Weibull lifetime model, able to describe an aging phenomenon, is used and it can be shown that the deterioration is statistically significant. The validity of the model is tested. We also analyse the influence of environmental covariates. We simulate different scenarios in order to investigate the impact of several maintenance strategies as well as on future maintenance costs, on the amount of components to replace based on the mean age of the network. It can be shown that in most cases a systematic replacement strategy offers the best solution.

• 대한토목학회논문집
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• 제37권5호
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• pp.879-890
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• 2017

기존 미국의 포장 설계법(AASHTO)과 대표적인 도로포장 유지보수 의사결정시스템인 HDM-4는 국내 실정 또는 환경에 적합하지 않아 현실적인 도로설계, 시공 및 유지관리 차원에서 국내에 적합하지 않다. 포장 수명 연장에 따른 환경비용에서도 차이가 발생할 것으로 판단되는 바, 본 연구의 주요 목표는 대한민국의 환경조건과 차종별 특성을 반영한 한국형 도로포장 설계법(KPRP) 설계 소프트웨어의 도로 공용성 해석 모델을 기반으로 활용하여 운영 및 유지보수단계에서 대표적인 세 가지 유지보수전략별 LCCC 계산을 통해 최적 대안을 선정하는 것이다. 본 연구 결과 40년 동안의 누적 탄소배출량은 대안 2의 절삭 및 덧씌우기가 누적 탄소배출량과 LCCC의 현재가치비용이 제일 적은 것으로 분석되었다. 본 연구를 통해 다양한 도로관리 유지보수 공사별 $CO_2$배출 원단위 구축이 가능하며 향후 탄소요금의 증가에 따른 도로시설별 다양한 유지관리 전략 마련에 대한 기초연구를 수행하였다는 점에 의의가 있다.

• KIEAE Journal
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• 제10권3호
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• pp.63-74
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• 2010

The general housing causes various environmental problems on the squandering of the resources and the production of the construction wastes, as it was removed and rebuilt because of the short-life in 20-30 years after constructing. The short-life of the general housing makes the rebuilt-term short and takes a negative attitude in maintenance. In the other hand, the long-life housing is constantly dwelling house that considers the carbon reduction among the world issues, Support and Infill. The long-life housing promotes the durability of Support and maximize the variability of Infill through separation of Support & Infill. It's useful dwelling house in maintenance as well as various life-cycle and life style. As the maintenance guideline of dwelling house is used for long-life housing, there is not distinction considering who controls maintenance and there is not conception considering alteration, variability and convenience. Consequently, it is required to develop the proper maintenance guideline applied maintenance process for long-life housing. Therefore this study shows efficient maintenance guideline for manager in long-life housing.