• Smart Structures and Systems
• /
• v.4 no.5
• /
• pp.641-653
• /
• 2008

This paper proposes a practical and realistic method to establish an optimal lifetime maintenance strategy for deteriorating bridges by considering the life-cycle performance as well as the life-cycle cost. The proposed method offers a set of optimal tradeoff maintenance scenarios among other conflicting objectives, such as minimizing cost and maximizing performance. A genetic algorithm is used to generate a set of maintenance scenarios that is a multi-objective combinatorial optimization problem related to the lifetime performance and the life-cycle cost as separate objective functions. A computer program, which generates optimal maintenance scenarios, was developed based on the proposed method using the life-cycle costs and the performance of bridges. The subordinate relation between bridge members has been considered to decide optimal maintenance sequence and a corresponding algorithm has been implemented into the program. The developed program has been used to present a procedure for finding an optimal maintenance scenario for steel-girder bridges on the Korean National Road. Through this bridge maintenance scenario analysis, it is expected that the developed method and program can be effectively used to allow bridge managers an optimal maintenance strategy satisfying various constraints and requirements.

• Journal of KIBIM
• /
• v.10 no.3
• /
• pp.1-11
• /
• 2020

The introduction of BIM technology is expanding not only in the field of design and construction, but also in the maintenance and use stage. In particular, researchers are looking to build a smart facility management system that integrates advanced IT technology and BIM. This study proposes the parts to be used and added to the BIM information, focusing on information generated and exchanged in the application case that is an issue during the current facility maintenance work by introducing the smart facility management technology and its use cases. The effectiveness of this proposal is compared with the scenario in which BIM-based facility safety management is applied and the current business scenario. In conclusion, the requirements for smart facility management are analyzed, and linkable parts between facility management tasks and BIM data that should be reflected in the facility management system are presented. In the maintenance phase, through the use case scenario, the facility management phase is subdivided according to the characteristics and contents of the work. In addition, information about the facilities required for each task is specified. Furthermore, it is examined whether BIM data and IT information can be linked with existing facility management systems. It is a process and guideline that can be provided to practitioners who want to introduce BIM and smart technology to facility management. It can define the required data items and levels according to the required information step by step based on the maintenance case.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.6
• /
• pp.677-686
• /
• 2006

In this paper, a more practical and realistic method is proposed to establish the lifetime optimum maintenance strategies of the deteriorating bridges considering the life-cycle performance as well as life-cycle cost. The genetic algorithm is applied to generate the set of maintenance scenarios that is the multi-objective combinatorial optimization problem related to lifetime performance and cost as separate objective functions, and the technique to select optimum tradeoff maintenance scenario is presented. Optimum maintenance scenarios could be generated not only at the individual member level but also at the system level of the bridge. Through the analytical results of applying the proposed methodology to the existing bridge, it is expected that the methodology will be effectively used to determine the optimum maintenance strategy for introducing a real preventive maintenance system and overcoming the limits of existing maintenance methods.

• IE interfaces
• /
• v.15 no.3
• /
• pp.286-296
• /
• 2002

Products which are sold with warranty, preventive maintenance actions by manufacturers and/or buyers have an impact on the total costs for both parties. In this paper, we develop the models to study the expected warranty cost for products with free repairable warranty with three types of discrete preventive maintenance. We deal with by utilizing the concept that preventive maintenance reduces the virtual age of the system. We assume that the maintenance planning horizon can be segmented into k discrete and equally sized periods. In such a scenario, numerical examples are presented.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.12
• /
• pp.181-188
• /
• 2019

The maintenance of school building is pivotal issue. However, it is difficult to obtain basic analysis data for LCC(Lifecycle Cost) analysis and maintenance planning of school building. Therefore, this study proposed System Dynamics(SD) techniques to make maintenance decisions for school building. The interaction between the major parameters related to the aging of a building, maintenance activities, and cost were expressed in Causal Loop Diagram. Based on this, the formula for the relationship between causal maps was defined and converted to Stock and Flow Diagram. Through the completed SD model the 50-year plan of 214 educational building were tested by considered in account budget, maintainability, and budget allocation opinions. As a result, the integrated SD model demonstrated that it can support strategic decision making by identifying the status class and LCC behavior of school buildings by scenario. According to the scenario analysis, the rehabilitation action of preventive maintenance that primarily repairs the buildings in condition grade C showed the best performance improvement effect relative to the cost. Therefore, if the proposed SD model is expanded to consider the effects of other educational policies, the crucial performance improvement budget can be estimated in the long-term perspective.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.11 no.4
• /
• pp.109-120
• /
• 2007

In this study, a bridge maintenance system is developed to generate performance-based optimum maintenance strategy by considering the life-cycle cost. A multi-objective combinatorial optimization problem is formulated to generate a tradeoff maintenance scenarios which satisfies the balance among the conflicting objectives such as the performance and cost during the bridge lifetime and a genetic algorithm is applied to the system. By using the developed program, this study proposes a process of optimum maintenance scenario applying to the steel girder bridge of national road. The developed system improves the current methods of establishing the bridge maintenance strategy and can be utilized as an efficient tool to provide the optimum bridge maintenance scenario corresponding to the various constraints and requirements of bridge agency.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.4
• /
• pp.505-516
• /
• 2018

In order to establish an efficient bridge maintenance strategy, the future performance of a bridge must be estimated by considering the current performance, which allows more rational way of decision-making in the prediction model with higher accuracy. However, personnel-based existing maintenance may result in enormous maintenance costs since it is difficult for a bridge administrator to estimate the bridge performance exactly at a targeting management level, thereby disrupting a rational decision making for bridge maintenance. Therefore, in this work, we developed a representative performance prediction model for each bridge element considering uncertainty using domestic bridge inspection data, and proposed a bayesian updating method that can apply the developed model to actual maintenance bridge with higher accuracy. Also, the feasibility analysis based on calculation of maintenance cost for monitoring maintenance scenario case is performed to propose advantages of the Bayesian-updating-driven preventive maintenance in terms of the cost efficiency in contrast to the conventional periodic maintenance.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2007.11a
• /
• pp.167-174
• /
• 2007

This study proposes a practical and realistic method to establish an optimal lifetime maintenance strategy for deteriorating bridges by considering the life-cycle performance as well as the life-cycle cost. The proposed method offers a set of optimal tradeoff maintenance scenarios among other conflicting objectives, such as minimizing cost and maximizing performance. A genetic algorithm is used to generate a set of maintenance scenarios that is a multi-objective combinatorial optimization problem related to the and the life-cycle cost and performance as separate objective functions. A computer program, which generates optimal maintenance scenarios, was developed based on the proposed method. The subordinate relation between bridge members has been considered to decide optimal maintenance sequence. The developed program has been used to present a procedure for finding an optimal maintenance scenario for steel-girder bridges on the Korean National Road. Through this bridge maintenance scenario analysis, it is expected that the developed method and program can be effectively used to allow bridge managers an optimal maintenance strategy satisfying various constraints and requirements.

• Journal of Astronomy and Space Sciences
• /
• v.37 no.1
• /
• pp.51-60
• /
• 2020

This study designs and analyzes satellite formation flying concepts for the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE) mission, that will observe the near-Earth space environment using four nanosats. To meet the requirements to achieve the scientific objectives of the SNIPE mission, three formation flying concepts are analyzed: a cross-shape formation, a square-shape formation, and a cross-track formation. Of the three formation flying scenarios, the cross-track formation scenario is selected as the final scenario for the SNIPE mission. The result of this study suggests a relative orbit control scenario for formation maintenance and reconfiguration, and the initial relative orbits of the four nanosats meeting the formation requirements and thrust limitations of the SNIPE mission. The formation flying scenario is validated by calculating the accumulated total thrust required for the four nanosats. If the cross-track formation scenario presented in this study is applied to the SNIPE mission, it is expected that the mission will be successfully accomplished.

• Journal of the Korean Institute of Gas
• /
• v.8 no.3 s.24
• /
• pp.37-42
• /
• 2004

This study established a catastrophic scenario and a likely scenario by qualitative and quantitative risk assessments to consider climate condition with season, and assessed efficiency of safety management cost with scenarios by cost-benefit analysis. As results, the catastrophic scenario was the maintenance error for unsteady state operation, and the likely scenario was the gas release accident at node $\sharp$4 of HAZOP Also, benefit/cost ratios for total safety management cost and effective items of safety management could be assessed at each scenario.