KR20090072223A - Methodology of network level optimum management system for infrastructures based on life cycle performance and cost - Google Patents

Abstract

An optimum management system building method of a network level based on life cycle performance and cost of infrastructures is provided to build the optimum maintenance management strategy of an individual structure level according to a given budget, thereby realizing a maintenance management system in advance. A maintenance management structure and a budget are built based on a project level of an infrastructure. Future budget establishment/repair and reinforcement/reconstruction priority are selected based on a network level about the entire infrastructure. The optimum management method satisfying a limited condition in a project level and a network level is built while repetitively performing the two steps. A budget by year becomes equal by repetitively performing the optimum process of the network level and the project level.

Description

METHODOLOGY OF NETWORK LEVEL OPTIMUM MANAGEMENT SYSTEM FOR INFRASTRUCTURES BASED ON LIFE CYCLE PERFORMANCE AND COST}

The present invention is to establish the optimal maintenance strategy of the individual structures and to establish the optimal maintenance budget at the entire structure level through the exchange of information on the individual structure level and information of the entire structure level for the social infrastructure such as bridges and tunnels The present invention relates to a method for establishing an optimal management system at the network level based on the life cycle performance and cost of social infrastructure.

In the period of high growth since the 1970s, the construction of social infrastructure itself was the subject matter. During this period, the management method through the replacement of damaged parts without special maintenance strategy for social infrastructure was the main solution for the maintenance of infrastructure.

In the mid-1990s, the collapse of multi-use structures, including bridges, increased the interest and awareness of the maintenance of infrastructure.

Since then, a lot of efforts and developments have been made for the safe and rational maintenance of infrastructures for more than a decade. Recently, the maintenance of infrastructures has been based on pre-established strategies that go beyond the measures taken when problems arise. Efforts are being made to maintain social infrastructure.

These efforts are made in terms of structural and detailed aspects, and evaluations of deterioration and repair reinforcement effects according to materials and mechanical properties are made at the individual project level composed of the element level and the combination of members. ought.

In addition, from an economic and macro perspective, efforts are being made to establish effective methods and future budgets for the management of the entire network level.

At present, the life cycle performance of the detailed members (or elements) that make up the social infrastructure structure and the cost estimation accordingly establish concrete maintenance strategies and costs according to the optimization of multiple combinations, Assuming a change of state of the structure, it has been proceeded in two directions to manage the economic point of view.

However, as can be seen from the recent collapse of major social infrastructure such as the bridge in Mississippi, USA, it is inseparably related to the accurate evaluation of structure performance and the budgeting and distribution for reasonable maintenance measures.

Therefore, it overcomes the limitations of existing social infrastructure management systems and is microscopically independent of the assessment of life cycle performance and life cycle costs of individual members and systems (eg bridges, tunnels, ports, etc.). It is necessary to develop a practical way to establish and allocate an economic budget considering preventive maintenance in the concept of asset management of the entire social infrastructure.

In detail, in the case of bridges among social infrastructures, a method of establishing an optimal maintenance strategy has been developed by improving the maintenance system in consideration of the life cycle performance and the cost conditions at the individual bridge level. .

At this time, the conventional method for establishing a maintenance strategy determines variables such as maintenance cost, timing of applying maintenance measures, and degree of performance improvement according to the applied measures for maintenance considering the performance change and life cycle cost of the bridge over time. The maintenance strategy for the individual bridges will be established taking into account the cost of maintenance measures, the time of application, and the resulting change in performance.

In general, however, bridge managers must simultaneously manage multiple bridges within their jurisdiction, which requires an optimal management strategy that takes into account both the bridge performance associated with the bridge's safety and the costs associated with the required or given budget. do.

This optimal management strategy minimizes the maintenance costs incurred while securing sufficient safety performance for the entire bridge to be managed and prevents the establishment of the required budget and the rapid increase or decrease of the budget through future management budget prediction. It should be a way to equalize the budget through preventive maintenance.

In Korea, bridges have been rapidly built around the 1990s, and the demand for maintenance is expected to increase from about 20 years, and the demand for reconstruction will increase from about 45-50 years.

Therefore, through continuous performance evaluation and cost estimation of bridges, we will identify future maintenance demands and renovation demands, and by using preventive maintenance measures, decentralize the rapid increase in budgets and fail to secure bridge performance due to lack of budgets. The occurrence of problems such as sudden traffic control or collapse should be minimized.

So far, the optimization applied to the existing domestic bridge management does not take into account the change in performance and cost according to the specific construction method of each reinforcement by dividing maintenance measures into simply reinforcement or replacement.

In addition, no prediction of future performance and cost for the entire bridge structure at the network level is made.

Accordingly, the present invention provides sufficient safety at the entire network level through estimation of reinforcement and replacement time and repair reinforcement method and cost according to the maximum performance and minimum cost for the individual project level at the same time. It is possible to establish future budgets while maintaining a constant level, and then to establish optimal maintenance strategies at the individual structure level according to the given budget, bringing the effect of introducing a preventive glass management system and optimizing future maintenance budgets to a certain level. It aims to provide a network-level optimal management system based on the life cycle performance and cost of social infrastructure.

According to an embodiment of the present invention, a method for establishing an optimal management system at a network level based on life cycle performance and cost of a social infrastructure includes: (a) establishing a maintenance strategy and a budget at a project level of an individual member and a social infrastructure; (b) selecting priorities for future budgeting, reinforcement and reconstruction at the network level for the entire infrastructure; And (c) repeating steps (a) and (b) to establish an optimal management method that satisfies the limited conditions at the project level and the network level.

In the method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention, the step (b) is performed by using the future performance evaluation and the estimated future budget of the entire social infrastructure. The introduction of a preventive maintenance strategy ensures that annual budgets are equalized by repeatedly performing network- and project-level optimizations so that budgets are not biased in a particular year, but require similar maintenance budgets throughout the entire maintenance period. It further includes budgeting steps for each future year.

In the method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention, the step (b) is performed at the project level when performing the budgeting step for each future year. When the cumulative maintenance costs over time are determined, the sum of the costs of the individual infrastructures establishes the budget for the maintenance of the entire management infrastructure, and the maintenance budget for the entire infrastructure at the network level at a specific point in time. In this case, the budgeting step according to the cumulative budget for each year is further included, by adjusting the original maintenance budget for each individual infrastructure in a similar ratio to newly establish the maintenance strategy for each individual infrastructure. .

In the method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention, step (b) is performed when the annual maintenance budget optimized at the network level is determined. It further includes a budget allocation step for each future year, in which individual bridges are optimized to a performance level close to the target performance level according to the performance level, thereby allocating an appropriate maintenance budget to maintain that performance level.

In the method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention, the step (b) is based on the entire social infrastructure at the network level within a predetermined budget when the budget is limited. At the project level, each individual infrastructure-based structure selects an optimal maintenance strategy that satisfies the limited conditions in consideration of the limited cost for the specified maintenance period, and presents the performance of the structure to the level of safety-free. Determine the optimal maintenance strategy for a set of solutions that extract only solutions that satisfy the limited budget from the solutions obtained without constraints, and maintain the optimal balance of performance and cost for the specified maintenance period while satisfying the budget constraint. More steps to find the best solution to choose It should.

According to an embodiment of the present invention, the method for establishing an optimal management system at a network level based on the life cycle performance and cost of a social infrastructure includes maintaining and managing future social infrastructure at the network level when a target performance level is determined in the step (b). In the budgeting process, the index of performance in the solution set of the individual infrastructures at the project level is selected so that the least cost scenario can be selected while satisfying the target performance in order to manage the infrastructures above a specific target performance. Selecting a solution that is more than a target performance and has a minimum cost, and finds an optimal solution by calculating a total required maintenance budget while maintaining a similar level of performance for the entire infrastructure at the network level.

In the method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention, the step (c) is an optimum established by considering the performance and cost at the individual social infrastructure structure level. Based on the results of the maintenance strategy and budget, the method further includes establishing and budgeting a specific yearly maintenance strategy analyzed for the entire infrastructure.

In the method for establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention, step (c) is performed by the individual society according to the increase and decrease of the annual budget inputted at the network level. In order to maintain the performance of the base structure above a certain level, it is necessary to adjust the maintenance method and the timing of action through the establishment of an optimal maintenance strategy and budget at the level of the individual infrastructure. It further includes establishing a preventive maintenance system to apply proactive maintenance measures before they occur.

In the present invention, in the maintenance of social infrastructure such as bridges and tunnels, the future budget is established at the network level using the maintenance strategy and the cost at the individual structure level, and the budget for the social infrastructure to be managed at the network level is established. In the case of constraints, at the network level based on the establishment of a new maintenance strategy for the individual infrastructure at the project level and the results at the newly established project level, while ensuring a certain level of safety for the entire infrastructure within a limited budget. Optimal management of the entire infrastructure to be managed can be enabled, enabling the realization of a preventive maintenance system.

In addition, the present invention is a desired point of time while satisfying the budget constraints while ensuring the safety of the entire infrastructure to establish or manage the long-term maintenance budget for the entire infrastructure at the network level of management entities and managers of the infrastructure infrastructure Can be used reasonably for budget execution.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a method for establishing an optimal management system at a network level based on life cycle performance and cost of a social infrastructure according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a method for establishing an optimal maintenance strategy and a budget at a project level. It is a figure which shows.

1 and 2, a method for establishing an optimal management system at a network level based on life cycle performance and cost of a social infrastructure according to an exemplary embodiment of the present invention is a maintenance strategy at a project level of an individual member and a social infrastructure. Optimal management method that satisfies the limited conditions at the project and network level through the steps of budgeting and budgeting, future budgeting and reinforcement at the network level for the entire social infrastructure, selecting priorities for reconstruction, and repeating the above two steps It consists of establishing a step.

Here, the maintenance strategy and budgeting step at the project level of individual members and bridges is a life cycle performance evaluation step 100, a life cycle cost evaluation step 200 and an optimal maintenance scenario generation step as shown in FIG. It consists of 300.

At this time, the life cycle evaluation step 100 is a statistical analysis of the maintenance history (101) of the bridge for the bridges of the similar type to the bridge given the basic bridge information (99) Through analyzing the deterioration factor for each member (102) and select the reinforcement alternative for each deterioration factor (103).

At this time, an initial reliability evaluation 105 is performed according to the basic reliability analysis model 104 for each deterioration factor of each member, and the deterioration degree for each deterioration factor of each member is calculated according to the initial reliability evaluation 105.

Then, the initial state evaluation model 106 is determined according to the analysis of the maintenance history 101.

In addition, the reinforcement reinforcement effect analysis 107 is performed according to the reinforcement reinforcement alternative selection 103 value and the initial reliability evaluation model 105 value for each deterioration factor, and the performance evaluation for each member according to the initial state evaluation model 106 value ( 109) is made.

In this case, the performance evaluation 109 for each member may be updated according to the result of the status evaluation 108 such as the current inspection and diagnosis.

The result of the performance evaluation 109 for each member produces a performance curve 110 for each member such as a confidence index curve and a state index curve, and is applied to the estimation of the failure cost 204 according to the failure probability.

The life cycle cost evaluation step 200 estimates user costs through basic bridge information 99, such as traffic characteristics of the bridge, and a regression model 200 developed for estimating road user costs. An analysis for estimating maintenance cost information 203 for each member is performed from 101.

Also, from the selected deterioration reinforcement alternative 103 and maintenance cost information 203, the reinforcement cost analysis 205 according to general maintenance activities is performed, and from the annual damage cost 204 according to the probability of failure. Reinforcement cost analysis 205 is performed.

Accordingly, the application reinforcement alternative selection 206 is made according to the reinforcement cost analysis 205 and the reinforcement effect analysis 107.

The optimal maintenance scenario generation step 300 is generated by the optimization algorithm 304 using the results of the life cycle evaluation step 100 and the life cycle cost evaluation step 200 described above.

Based on the member-specific performance curve 110 and the selected application reinforcement alternative 206, a tradeoff between cost and performance is generated by the optimization algorithm 304.

In addition, the performance curve 110 for each member is integrated into the system performance curve 303 by the system reliability or weighting factor 302, and the dependency relationship according to the maintenance measures for each member is taken into consideration so that the optimal maintenance scenario (at the bridge system level) 305 is generated via the optimization algorithm 304.

After this step of establishing maintenance strategies and budgets for individual parts and bridges at the project level, the maintenance strategies and budgeting information for the individual parts and bridges at the project level can be used for the entire bridge. To set the priorities for future budgeting, remuneration, and reconstruction at the network level.

At this time, the step of setting the prior budget, rehabilitation, and reconstruction priorities at the network level for the entire bridge is analyzed by analyzing the information transmitted through the maintenance strategy and budgeting steps at the project level of the individual member and bridge After detecting the total bridge information, we estimate the future performance and estimate the future budget of the entire infrastructure using the detected information.

At this time, in the performance evaluation and future budget estimation stage, the composition and budget of the specific annual maintenance strategy analyzed for the entire bridge based on the result of the optimal maintenance strategy and budget established considering the performance and cost at the individual bridge level To enable the establishment of

After that, the introduction of a preventive maintenance strategy, using the future performance assessment of the entire infrastructure and the estimated future budget, ensures that a similar maintenance budget is spent over the entire maintenance period, without biasing the budget for a particular year. It performs the budgeting step of the future year to equalize the yearly budget by repeatedly performing the level and project level optimization process.

At this time, if the cumulative maintenance cost according to the time of the individual social infrastructure (eg bridge) is determined at the project level when performing the budgeting step for the future year, the maintenance budget of the entire management bridge through the sum of the costs of the individual bridges If the maintenance budget for the entire bridge is determined at the network level at a specific point in time, then the maintenance budget for each individual bridge can be adjusted at a similar level by adjusting the original maintenance budget for each individual bridge. Perform budgeting steps based on the cumulative annual budget.

That is, as shown in FIG. 4, if the cumulative maintenance cost of the individual bridges is determined at the project level, the maintenance budget of the entire management bridge can be established through the sum of the costs of the individual bridges. When the maintenance budget for the entire bridge is established, a new strategy for maintenance of each individual bridge is established at the project level by adjusting the original maintenance budget for each individual bridge in a similar proportion.

After establishing a budget for each future year, the allocation cost of the individual infrastructure is calculated and then compared with the budget.

At this time, if the optimized annual maintenance budget is determined at the network level, the individual bridges are optimized to the performance level close to the target performance level according to the performance level of the individual bridges, and the appropriate maintenance budget is allocated to maintain the performance level at that time. Perform budget allocation steps for each future year.

As shown in FIG. 3A and FIG. 3B, the budgeting and distribution step for each future year maintains a certain level of performance of the infrastructure based on the entire maintenance period such as the construction of a bridge, generation of maintenance demand, and opening demand. To make sure that the budget is uniform.

In this case, it is achieved by Equation 1 to combine the member level performance (state index, confidence index) and the cost of the members constituting each bridge at the project level with the system level performance and cost.

는 각 시간 t에서 교량의 시스템상태지수, 시스템 최소신뢰지수, 시스템 비용합; N은 고려된 부재의 수; λ는 상태지수에 대한 부재별 가중치.here

Is the sum of the system health index, system minimum confidence index, and system cost of the bridge at each time t; N is the number of members considered; λ is the weight for each member for the state index.

In addition, performance and cost at the network level are made as a function of project level results and can be conceptually represented as Equation 2.

는 각각 시간 t에서 교량의 네트워크 수준에서의 상태지수, 신뢰지수, 비용합;

은 프로젝트 수준에서 관리 대상 교량시스템 각각의 상태지수, 신뢰지수, 비용합; n은 관리되고 있는 교량 수; f는 프로젝트 수준의 교량 결과를 바탕으로 네트워크 수준의 결과 도출을 위해 정의되는 함수(function).here

Is the state index, confidence index, and cost sum at the network level of the bridge at time t, respectively;

Is the sum of the state index, confidence index, and cost of each bridge system to be managed at the project level; n is the number of bridges being managed; f is a function defined to derive network level results based on project level bridge results.

If there are budget constraints in the future budgeting and distribution stages as shown in FIG. 5, the performance of the entire bridge at the network level within the budget set as shown in FIG. Each individual bridge selects the optimal maintenance strategy that satisfies the limited conditions in consideration of the limited costs during the specified maintenance period, and extracts only the solution that satisfies the limited budget from the solution obtained without budget constraints. Determine the optimal maintenance strategy to find the optimal solution to select a maintenance strategy that best balances performance and cost over a given maintenance window while meeting budget constraints.

Here, FIG. 5 is a diagram illustrating a budget establishment method according to an annual cumulative budget.

In general, as the number of bridges increases and ages, the budget is not always sufficient.

In such a case, the performance of the entire bridge at the network level within the budget should be presented at a safe level.

If the network-level bridge maintenance budget established for the next 10 years is limited as shown in Figure 5, at the project level, each individual bridge will have a limited cost during the maintenance period, which will determine the optimal maintenance strategy that satisfies the limited conditions. The selection is made with consideration.

In this case, the optimal maintenance strategy for the set of solutions that extract only the solutions that meet the limited budget from the solutions obtained without budget constraints is optimally balanced for performance and cost during the specified maintenance period while satisfying the budget constraints. You can choose a maintenance strategy.

For example, if the maintenance budget for 10 years is limited to 300 million won, a balanced year among the selected alternatives may be selected by selecting an alternative having a cost of 300 million won or less for 10 years among the total years as shown in FIG. You can find it.

When the target performance level is determined, as shown in FIG. 6, in the process of establishing a future bridge maintenance budget at the network level, the minimum cost is generated while satisfying the target performance in order to manage the bridge above a specific target performance. In order to select a scenario, select a solution at the project level with a state index above the target performance and a minimum cost in the set of individual bridges to maintain a comparable level of performance for the entire bridge at the network level while maintaining the overall required budget. To find the optimal solution.

6 is a diagram illustrating a method of finding an optimal solution having a minimum cost when a target performance level is determined.

In developing future bridge maintenance budgets at the network level, you may want to manage bridges above specific target performance.

In this case, you should be able to select the scenario that meets the target performance and incurs the least cost.

For example, if the bridge management entity wants to manage the performance index of the bridge at 80 or higher, the solution level of the individual bridge at the project level is 80 or more in the solution set of individual bridges at the project level. It is possible to select the total required maintenance budget while maintaining the legacy level of performance for the entire bridge at the level.

As such, the priorities for reinforcement and reconstruction of the entire social infrastructure are calculated using budget allocation information for each future year.

Afterwards, in order to maintain the performance of individual social infrastructures above a certain level according to the increase and decrease of annual budgets determined and input at the network level using the calculated reinforcement and reconstruction priorities of the entire social infrastructure structures. By establishing optimal maintenance strategies and budgets at the structure level, adjustments are made to the timing of maintenance methods and actions to establish a maintenance strategy to apply proactive maintenance measures before structural performance problems arise in the infrastructure. Carry out the establishment of a preventive maintenance system.

As described above, the method for establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to the embodiment of the present invention is performed at the individual structure level in maintaining the social infrastructure such as bridges and tunnels. Use a maintenance strategy and costs to establish a future budget at the network level and, if there is a budget constraint on the managed infrastructure at the network level, ensure that the project has a certain level of safety for the entire infrastructure within the limited budget. Based on the establishment of a new maintenance strategy for individual social infrastructure structures at the level and the results at the newly established project level, optimal management of the entire social infrastructure structure to be managed at the network level is possible, enabling the practical preventive maintenance system to be realized. Can It is.

In addition, the method for establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure according to an embodiment of the present invention provides long-term maintenance of the entire social infrastructure at the network level of the management entities and managers of the social infrastructure. The security of the entire social infrastructure that establishes or manages the budget can be secured while satisfying the budget constraints and making reasonable use of the budget at the desired time.

1 is a diagram illustrating a method of establishing an optimal management system at a network level based on life cycle performance and cost of a social infrastructure according to an exemplary embodiment of the present invention.

2 is a diagram illustrating an optimal maintenance strategy and budgeting method at the project level.

3A and 3B illustrate an equal distribution concept of future budgets through preventive maintenance.

4 is a diagram illustrating a budget establishment method according to a yearly cumulative budget.

5 is a diagram illustrating a method of finding an optimal solution that satisfies a constraint when there is a budget constraint.

6 is a diagram illustrating a method of finding an optimal solution having a minimum cost when a target performance level is determined.

Claims (8)

(a) a maintenance strategy and budgeting phase at the project level of individual absences and infrastructure; (b) selecting priorities for future budgeting, reinforcement and reconstruction at the network level for the entire infrastructure; And (c) repeating steps (a) and (b) to establish an optimal management method that satisfies the limited conditions at the project level and the network level. And how to establish an optimal management system at the network level based on cost. The method of claim 1, Step (b) is Using the future performance evaluation of the entire infrastructure and the estimated future budget, the introduction of a preventive maintenance strategy will ensure that a similar maintenance budget is required throughout the entire maintenance period without any bias in the budget. And a step of establishing a budget for each year based on the life cycle performance and cost of the social infrastructure, characterized in that it further comprises a step of optimizing the annual budget by repeatedly performing a project level optimization process. . The method of claim 2, Step (b) is When carrying out the budgeting step for each future year, when the cumulative maintenance cost of each social infrastructure is determined at the project level, the maintenance budget of the entire management social infrastructure is established through the sum of the costs of the individual social infrastructure. If the maintenance budget for the entire social infrastructure is determined at the network level at a specific point in time, the maintenance strategy of each individual social infrastructure at the project level is adjusted by adjusting the original maintenance budget for each individual infrastructure at a similar rate. The method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure, characterized in that it further comprises a budgeting step according to the yearly cumulative budget to establish a new. The method of claim 3, wherein Step (b) is If the optimized annual maintenance budget is determined at the network level, the individual bridges are optimized to the performance level close to the target performance level according to the performance level of the individual bridges, thereby allocating a maintenance budget suitable for maintaining the performance level at that time. A method of establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure, further comprising a budget allocation step for each future year. The method of claim 4, wherein Step (b) is If there is a constraint of the budget, each individual infrastructure is required to maintain an optimal maintenance strategy that satisfies the limited conditions. It selects in consideration of the limited cost during the specified maintenance period, and determines the optimal maintenance strategy for the solution set that extracts only the solution that satisfies the limited budget from the solution obtained in the absence of the budget constraint to satisfy the budget constraint. And a network level optimal management system based on the life cycle performance and cost of the infrastructure, characterized in that it further comprises the step of finding an optimal solution for selecting a maintenance strategy that is optimally balanced between performance and cost for a given maintenance period. How to establish. The method of claim 5, wherein If the target performance level is determined in the step (b), the minimum cost is satisfied while the target performance is satisfied in order to manage the infrastructure in the future at the network level in order to manage the infrastructure above a specific target performance. To select the scenarios that occur, select a solution at the project level where the performance index is above the target performance and the cost is minimal in the solution set of the individual social infrastructure structures, and then similar to the overall social infrastructure structures at the network level. A method of establishing an optimal management system at a network level based on the life cycle performance and cost of a social infrastructure, comprising: calculating an overall required maintenance budget while maintaining a level of performance. The method of claim 1, Step (c) is Based on the results of the optimal maintenance strategy and budget established in consideration of performance and cost at the level of the individual infrastructure, the step of establishing and budgeting a specific yearly maintenance strategy analyzed for the entire infrastructure is further established. A method for establishing an optimal management system at the network level based on the life cycle performance and cost of the social infrastructure. The method of claim 7, wherein Step (c) is In order to maintain the performance of individual social infrastructures above a certain level according to the increase and decrease of the annual budget determined and input at the network level, a maintenance management method and an optimal management strategy and budget establishment at the individual social infrastructure structures level and Life cycle of the social infrastructure, further comprising the step of establishing a preventive maintenance system that performs an adjustment of the timing of the action to apply proactive maintenance before the structural performance problem occurs in the social infrastructure. How to establish an optimal management system at the network level based on performance and cost.

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