• Journal of Korean Society of Water and Wastewater
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• v.26 no.5
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• pp.619-627
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• 2012

In order to determine reduction of greenhouse gas emissions (GHGs) when the submerged membrane bioreactor with granular sulfur (MBR-GS) is used in wastewater treatment plant (WTP), the amount of GHGs was compared and analyzed in the advanced treatment process of P wastewater treatment plant (WTP). The amount of GHGs was estimated by classifying as construction and operation phase in WTP. The amount of GHGs in construction phase was evaluated from multiplying raw materials by using carbon emission factors. Also the amount of GHGs in operating phase was calculated by using total electricity consumption and carbon emission factor. The construction of anoxic tank and secondary settling tank is unnecessary, because the MBR-GS conducts simultaneously the nitrification and denitrification in aeration tank and filtration by hollow fiber membrane. The amount of $CO_2$, $CH_4$, and $N_2O$ emitted by constructing the MBR-GS was 6.44E+06 kg, 8.16E+03 kg and 1.38E+01 kg, respectively. The result shows that the GHGs was reduced about 47 % as compared with the construction in the MLE process. In operating the MBR-GS, the electricity is not required in the biological reactor and secondary setting tank. Thus, the amount of $CO_2$, $CH_4$, and $N_2O$ emitted by operating in the MBR-GS was 7.39E+05 kg/yr, 5.80E+02 kg/yr and 2.44E+00 kg/yr, respectively. The result shows that the GHGs were reduced about 37 % as compared with the operation in the MLE process. Also, $LCCO_2$(Life Cycle $CO_2$) was compared and analyzed between MLE process and MBR-GS. The amount of $LCCO_2 $emitted from the MLE process and MBR-GS was 3.56E+04 ton $CO_2$ and 2.12E+04 ton $CO_2$, respectively. The result shows that the GHGs in MBR-GS were reduced to about 40 % as compared in the MLE process during life cycle. As a result, sulfur-utilizing autotrophic denitrification process (SADP) is expected to be utilized as the cost-effective advanced treatment process, owing to not only high nitrogen removal efficiency but also the GHGs reduction in construction and operation stage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.131-144
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• 2018

The urban center of a large city has a high concentration ratio of population, commerce, and traffic. Therefore, the expected effect is high from the introduction of the urban utility tunnel and it also has sufficient economic feasibility considering life cycle cost. Moreover, the construction cost can be greatly reduced if it is included in a large underground development such as a subway or a complex transfer center construction. However, it is not reflected in actual underground development plan. When planning a urban utility tunnel in Korea, it is expected to have difficulties such as the cost of relocation of the existing Life-Line, conflicts among the individual facility institutions, procurement of construction resources and sharing. Furthermore, it is possible to promote the project only if a consensus is drawn up by a collective council composed of all facilities and project developers. Therefore, an optimal alternative should be proposed using economic analysis and feasibility assessment system. In this study, the analytic hierarchy process (AHP) is performed considering the characteristics of urban areas and the importance of each indicator is quantified. As a result, we can support reasonable design capacity optimization using the feasibility assessment system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.153-161
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• 2020

Building information modeling (BIM) is a smart construction technique that is recognized as essential for current construction facility projects. The Public Procurement Service (a construction project-ordering agency) announced a plan to introduce BIM and has required changing the operation of projects by using BIM design information. LCC analysis is essential for items, quantity, and cost information of the construction, and it is expected that efficient work will be achieved by using BIM design information. In this study, a BIM-LCC analysis system was established for selecting optimal design alternatives by actively using open KBIMS libraries. The BIM-LCC analysis system consists of a single alternative and an optimal alternative LCC analysis, but it has a limitation in that only the architecture and machine libraries have been applied. However, by applying BIM, practical use and work efficiency can be expected. In order to use the method as an LCC analysis support tool with BIM design information in the future, it will be necessary to collect user opinions and improve the UI.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.974-982
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• 2009

To improve the effectiveness and economics the bridge design methodology considering the bridge/rail longitudinal analysis and bridge/vehicle dynamic effect suggested in this study. The reliability-based Life-Cycle Costs(LCC) effective optimum design is applied to a 2-main steel girder bridge, 5$\times$(1@50m) for comparison with conventional design, initial cost optimization and equivalent LCC optimization. As a result of the optimum design based on reliability, it may be stated that the design of High-Speed railway bridges considering the bridge/rail longitudinal analysis and bridge/vehicle dynamic effect are more efficient than typical existing bridges and LCC optimization without respect to bridge/rail longitudinal analysis and bridge/vehicle dynamic effect. The result of optimization design considering the interaction, design methodology suggested in this study, is higher than result of initial cost optimization design in initial cost, but that has the advantage than result of initial cost optimization design in expected LCC.

• Korean Journal of Construction Engineering and Management
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• v.17 no.2
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• pp.31-38
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• 2016

In a construction project, the portion for maintenance costs for a building is considerable compared to the initial construction cost. As such, Life Cycle Cost (LCC) analysis is being increasingly utilized to assess the design value of engineering work in Korea. Additionally, the Public Procurement Service in Korea announced that it will be mandatory for all domestic construction projects to adopt BIM. Furthermore, the paradigm for architectural design has shifted from 2D to 3D, and to BIM, which includes a data management system. Within this background, however, there is currently no adequate BIM-based LCC analysis software and the requirements of cost estimation for repair and replacement cost for a building is not completely adequate in BIM tools such as Revit and Archicad. Therefore, this study suggests a process of cost estimation for repair and replacement (R&R) cost based on IFC data. First, we analyzed existing R&R criteria and defined BIM-based requirements when calculating R&R costs. These requirements were extracted from relevant IFC data. Subsequently, this was saved to a database and a BIM-based database was built for R&R cost estimation. Finally, this database was connected with external databases such as R&R Criteria DB and Cost Information DB to calculate R&R costs. This process is expected to improve upon the traditional process of cost estimation of R&R cost by applying a BIM model. The proposed process can contribute to a further standardizing of BIM-based LCC analysis thru application to initial construction costs, energy costs, and other maintenance costs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.533-542
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• 2016

The periodic maintenance of bridges is necessary once they have been constructed and its cost depends on various factors, such as their condition, environmental conditions and so on. To make a decision support system, it is essential to establish a basic reconstruction cost model. In this study, a regression model is suggested for calculating the reconstruction cost for typical cases and influential factors, depending on the type of bridge and its components, by analyzing the basic bridge specifications based on the data of the Bridge Management System (BMS). The details for each case were estimated in consideration of the cost calculation variables. The details for each case were estimated in consideration of the cost calculation variables. The cost model for the new construction of the superstructure, substructure and foundation and the temporary bridge construction and demolition costs were drawn from the regression analysis of the estimation results of typical cases according to the cost calculation variables. The reconstruction costs for different types of bridge were obtained using the cost model and compared with those in the literature. The cost model developed herein is expected to be utilized effectively in maintenance decision making.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.2
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• pp.63-72
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• 2016

An expected-discounted cost model based on RRP(Renewal Reward Process), referred to as a stochastic decision model, has been developed to estimate the optimal period of in-depth inspection which is one of critical issues in the life-cycle maintenance management of harbor structures such as rubble-mound breakwaters. A mathematical model, which is a function of the probability distribution of the service-life, has been formulated by simultaneously adopting PIM(Periodic Inspection and Maintenance) and CBIM(Condition-Based Inspection and Maintenance) policies so as to resolve limitations of other models, also all the costs in the model associated with monitoring and repair have been discounted with time. From both an analytical solution derived in this paper under the condition in which a failure rate function is a constant and the sensitivity analyses for the variety of different distribution functions and conditions, it has been confirmed that the present solution is more versatile than the existing solution suggested in a very simplified setting. Additionally, even in that case which the probability distribution of the service-life is estimated through the stochastic process, the present model is of course also well suited to interpret the nonlinearity of deterioration process. In particular, a MCS(Monte-Carlo Simulation)-based sample path method has been used to evaluate the parameters of a damage intensity function in stochastic process. Finally, the present stochastic decision model can satisfactorily be applied to armor units of rubble mound breakwaters. The optimal periods of in-depth inspection of rubble-mound breakwaters can be determined by minimizing the expected total cost rate with respect to the behavioral feature of damage process, the level of serviceability limit, and the consequence of that structure.

• Economic Analysis
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• v.24 no.3
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• pp.1-36
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• 2018

When it comes to explaining the relationship between inventory investment and business fluctuations, the production smoothing theory and the stock-out avoidance theory take contradictory stances. Decision-making related to inventory investments of corporations is thought to be influenced by both motives, but the relative sizes or directions of their respective influences can differ depending upon the phase of the business cycle. Against this backdrop, this paper differs from existing studies in that it theoretically tests the relative significances of the production smoothing and stock-out avoidance motives in the inventory investment dynamics, while placing its analytical focus on determining the existence and patterns of the asymmetric dynamics of inventory investment over the business cycle phases. To this end this paper sets up a non-linear model that is expanded from the existing linear inventory investment model, and checks whether its predictive power is better than that of the existing model. The results of analysis confirm the nature of the asymmetric dynamics of inventory investment over the business cycle phases. A stock-out avoidance motive appears but there is no significant production smoothing motive in boom times. In downturns, in contrast, the stock-out avoidance motive is insignificant, but a quality of asymmetric dynamics in which changes in inventory cause the deepening of recessions, due to the non-convexity of production costs proposed by Ramey (1991), is detected. This paper confirms that a model considering the asymmetric dynamics of inventory investment can have better predictive power than one that does not consider it, through within-sample and out-of-sample predictions and various predictive power tests. These research results are expected to be useful for economic forecasting, through their enhancement of the understandings of the inventory investment dynamics and of the nature of its business cycle destabilization.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.293-298
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• 2006

The reinforced concrete(RC) structures strengthened with fiber reinforced plastic(FRP) has been accepted by the construction engineering community for rehabilitation. FRP composites can present many advantages like a corrosion resistance, strength-weight ratio, relatively short application time, and cost effectiveness. The beams under design load, however, are cracked and result in degrading the strength. It is difficult to recognize cracks and deflections on the surface of the concrete members retrofitted with FRP through the life cycle. For these reasons, if they result in the effects, which were below the expected strength, we must monitor the state of concrete structures all the time in order to take an appropriate measure. Fiber Bragg Grating(FBG) sensor excel as monitoring of investigating the stress state of the retrofitted beams with FRP. The main objective of this study is to measure strain by experiment and analyze the behavior of RC beams retrofitted with FRP using FBG sensor. The kinds of FRP which were used in research are carbon, glass and improved hybrid FRP(IFRP) that has capacity than any other FRP. Other variables are the length of FRP, the number of sheet.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.16-24
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• 2005

The goal of the present paper is to show the optimum design and operation conditions on 6 kW solar water heating system by using computer simulation with verified modelling. As the object functions, we took not only the amount of acquired and auxiliary heat but LCC, which has a relative importance and decisive role in economy. As expected, the maximum heat is acquired at the slope of collector with the equal degree to the latitude, facing the south. The capacity increase of the circulation pump and the storage tank lead to the increase of acquired heat and the decrease of auxiliary heat, but do not necessarily give economical advantages owing to additional electrical power consumption. In the present system, the minimum LCC can be obtained at the storage tank volume of 450 L and the mass flow rate of 0.344 kg/s.