• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.973-984
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• 2007

This study developed and calculated alternative evaluation index (AEI) from the effectiveness analyses of alternatives for rehabilitation of distorted hydrologic cycle. The feasible alternatives for the poor-conditioned region in the Anyangcheon watershed were proposed and quantitatively analyzed using continuous water quantity/quality simulation model, Hydrological Simulation Program-Fortran (HSPF). The effectiveness analyses include 355th flow and 275th flow of flow duration curve and number of increased days to satisfy the target monthly flow for water quantity and BOD average concentration, total daily loads and number of increased days to satisfy the target concentration and total daily loads. The feasible alternatives are restoration of covered stream, prevention of streamflow loss through sewers, redevelopment of existing reservoir, reuse of treated wastewater, use of groundwater collected by subway stations and construction of small wastewater treatment plant. Therefore, alternative priority ranking was derived from AEIs. It will be effective to make an integrated watershed management for sustainable development.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1106-1113
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• 2022

Cost segregation helps reduce tax liabilities by reclassifying real property to personal property and accelerates tax depreciation of a property. A typical cost segregation study requires much time and high costs. This study proposed a BIM integrated cost segregation process that can be applied to any commercial building project. The proposed BIM-based cost segregation process was verified in a new commercial construction project. It approved that this approach can: (1) increase the cash flow for the owner and provide assistance to tax-paying enterprises; (2) enable the contractor to use it as an added value in the bidding process; (3) realize data sharing in a common platform to improve the cost segregation study efficiency and reduce costs and errors; (4) contribute to the asset management in the life cycle of buildings while filling in the blank of cost segregation process. Future studies will focus on the automation of cost segregation and asset management in building construction's life cycle.

• Journal of Korean Society on Water Environment
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• v.36 no.4
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• pp.284-299
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• 2020

Dam reservoirs play a particularly crucial role in processing the allochthonous and the autochthonous dissolved (DOC) and the particulate (POC) organic carbon and in the budget of global carbon cycle. However, the complex physical and biogeochemical processes make it difficult to capture the temporal and spatial dynamics of the DOC and the POC in reservoirs. The purpose of this study was to simulate the dynamics of the DOC and the POC in Daecheong Reservoir using the 3-D hydrodynamics and water quality model (AEM3D), and to quantify the mass balance through the source and sink fluxes analysis. The AEM3D model was calibrated using field data collected in 2017 and showed reasonable performance in the water temperature and the water quality simulations. The results showed that the allochthonous and autochthonous proportions of the annual total organic carbon (TOC) loads in the reservoir were 55.5% and 44.5%, respectively. In season, the allochthonous loading was the highest (72.7%) in summer, while in autumn, the autochthonous loading was the majority (77.1%) because of the basal metabolism of the phytoplankton. The amount of the DOC discharged to downstream of the dam was similar to the allochthonous load into the reservoir. However, the POC was removed by approximately 96.6% in the reservoir mainly by the sedimentation. The POC sedimentation flux was 36.21 g-C/㎡/yr. In terms of space, the contribution rate of the autochthonous organic carbon loading was high in order of the riverine zone, the transitional zone, and the lacustrine zone. The results of the study provide important information on the TOC management in the watersheds with extensive stagnant water, such as dam reservoirs and weir pools.

• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.57-66
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• 2018

Water disasters such as flash floods and inundation caused by localized heavy rainfall in urban areas have a large impact on climate change but are also closely related to the increase in impervious areas as pointed out in domestic and international studies. It is difficult to secure natural green areas in urban areas that have already been developed. So, urban regeneration can be expected using water management optimized with technologies to secure infiltration and storage capacity such as Low-Impact Development technology. In this study, the water cycle improvement ability was confirmed by applying the LID technology within the district unit plan of the environmentally friendly village, and the economic feasibility of LID application was analyzed by estimating the costs and benefits of installing the facilities. The site was planned to conserve sufficient green and plans for securing the watershed infiltration and storage capacity were formulated with the application of additional LID technology, such as infiltration trenches, rain barrels and permeable pavements. The LID design method applicable to the site was established, and the water balance of the watershed was analyzed through simulations of the SWMM model. The water circulation improvement effect was confirmed through the water balance analysis, and the cost-benefits were determined according to the estimation method, and the economic analysis was conducted. This study confirms that the investment of LID technology is economically feasible for the hydrological improvement effect of the housing complex.

• Journal of Korean Society of Water and Wastewater
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• v.38 no.1
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• pp.29-38
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• 2024

Wastewater management is increasingly emphasizing economic and environmental sustainability. Traditional methods in sewage treatment plants have significant implications for the environment and the economy due to power and chemical consumption, and sludge generation. To address these challenges, a study was conducted to develop the Intermittent Cycle Extended Aeration System (ICEAS). This approach was implemented as the primary technique in a full-scale wastewater treatment facility, utilizing key operational factors within the standard Sequencing Batch Reactor (SBR) process. The optimal operational approach, identified in this study, was put into practice at the research facility from January 2020 to December 2022. By implementing management strategies within the biological reactor, it was shown that maintaining and reducing chemical quantities, sludge generation, power consumption, and related costs could yield economic benefits. Moreover, adapting operations to influent characteristics and seasonal conditions allowed for efficient blower operation, reducing unnecessary electricity consumption and ensuring proper dissolved oxygen levels. Despite annual increases in influent flow rate and concentration, this study demonstrated the ability to maintain and reduce sludge production, electricity consumption, and chemical usage. Additionally, systematic responses to emergencies and abnormal situations significantly contributed to economic, technical, and environmental benefits.

• Journal of Climate Change Research
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• v.9 no.4
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• pp.319-324
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• 2018

Due to climate change, water shortages and water-related disasters will be serious. Since the damage and frequency of drought are increasing, the importance of water resource management technology is increasing. In this study, we analyzed the amount of greenhouse gas and the environmental impact caused by the production and operation system technologies of movable weir among various water resource management technologies. The research subjects were air inflatable rubber dams widely used in rivers and upright type rubber dams, which are an improvement on the existing rubber type. Each type of dam was studied at sizes of $1,500H{\times}10,000L\;mm$ and $3,000H{\times}20,000L\;mm$, and the two types and two sizes were compared and analyzed. Using life cycle assessment, we examined the environmental impacts using the amount of electricity required for operation and the discretionary amount required for production. In the '$1,500H{\times}10,000L$' dams, the global warming indexes were $9.35E+04kg\;CO_2-eq$. for upright type and $7.36E+04kg\;CO_2-eq$. for inflatable type. At size of '$3,000H{\times}20,000L$' the global warming indexes were $9.09E+05kg\;CO_2-eq$. for upright type and $1.07E+06kg\;CO_2-eq$. for inflatable type. Analysis of the life cycle environmental impact showed that the environmental impact of the air inflatable rubber dam was reduced by 39.8% at '$1,500H{\times}10,000L$' compared to the larger size. At the larger '$3,000H{\times}20,000L$' size, the upright dam showed a 10.1% smaller impact than the air inflatable rubber dam. Selection of water resource management system should consider climate change, not only management purpose and cost. Additional studies and improvements on rubber dam systems should be made.

• Nuclear Engineering and Technology
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• v.39 no.4
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• pp.257-272
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• 2007

Supercritical water-cooled reactors (SCWRs) are recognized as a Generation IV reactor concept. The Super LWR is a pressure-vessel type thermal spectrum SCWR with downward-flow water rods and is currently under study at the University of Tokyo. This paper reviews Super LWR safety. The fundamental requirement for the Super LWR, which has a once-through coolant cycle, is the core coolant flow rate rather than the coolant inventory. Key safety characteristics of the Super LWR inhere in the design features and have been identified through a series of safety analyses. Although loss-of-flow is the most important abnormality, fuel rod heat-up is mitigated by the "heat sink" and "water source" effects of the water rods. Response of the reactor power against pressurization events is mild due to a small change in the average coolant density and flow stagnation of the once-through coolant cycle. These mild responses against transients and also reactivity feedbacks provide good inherent safety against anticipated-transient-without-scram (ATWS) events without alternative actions. Initiation of an automatic depressurization system provides effective heat removal from the fuel rods. An "in-vessel accumulator" effect of the reactor vessel top dome enhances the fuel rod cooling. This effect enlarges the safety margin for large LOCA.

• Land and Housing Review
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• v.6 no.4
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• pp.165-175
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• 2015

This study is focusing on the needs to introduce policy decision making based on identification of the definition for 'business life cycle' and 'public enterprises' for proper public enterprises management. For this purpose, the study is planning to define categorical variables for enterprise life cycle and provide basic data for public enterprises management policy. This study explored 'Korea Expressway Corporation', 'K-water', 'Korea Railroad', 'Korea Land and Housing Corporations', because of they are the public institutions recently underwent 'management normalization policy' due to rapidly increasing debt. First, there follows the analysis on priority and standard of categorical variables for quasi-market oriented SOC public enterprise life cycle by using AHP and frequency study on expert survey. Next, this study investigated and analyzed the enterprises management plan for expected 'declining period' through forecasting 'declining period' by conducting 2nd expert survey.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.83-94
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• 2016

Energy use has been recognized worldwide as a main cause of global warming and it is at the center of climate change. In this study, problems and measures of zero-energy building construction are investigated and analyzed. Based on the results, evaluation criteria of the zero-energy building are suggested. Performance related factors(Q) representing the environmental grade were divided into three categories as outdoor, indoor environment and maintenance. Energy related factors(LR) representing the energy load were divided into an energy, materials & resources, water cycle management, land use and transportation. Detailed fifty three items are listed for the evaluation under the consideration of energy, water cycle management sections gave weight. Upon receiving the first in the environment friendly certification system, Seoul Central Post Office and Seoul Metropolitan Water Supply Center evaluated. The reason why this score difference is due to lack of use of new generation energy building construction is required expensive costs so need expansion of governmental support. This effort is successful zero energy building construction and copes with global warming and climate change.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.833-843
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• 1998

It is noted that the red tides and the oxygen-deficient water mass are extensively developed in Masan Bay during summer. The nutrients mass balance was calculated in Masan Bay, using the three-dimensional numerical hydrodynamic model and the material cycle model. The material cycle model was calibrated with the data obtained on the field of the study area in June 1993. The nutrients mass balance calculated by the combination of the residual currents and material cycle model results showed nutrients of surface and middle levels to be transported from the inner part to the outer part of Masan Bay, and nutrients of bottom level to be transported from outer part to inner part of Masan Bay. The uptake rate of DIN in the box A1(surface level of inner part) was found to be 337. 5mg/$m^3$ㆍday, the largest value in all 9 boxes and that of DIP was found to be 18.6mg/$m^3$ㆍday in box A1, and the regeneration rate of DIN was found to be 78.2mg/$m^3$ㆍday in the box A3(bottom level of inner part), and that of DIP was found to be 18.6mg/$m^3$ㆍday in box A1. The regenerations of DIN and DIP in the water column of the entire Bay were found to be 7.66ton/day and 760kg/day, respectively. And the releases of DIN and DIP from the sediments of the entire Bay were found to be 2.86ton/day and 634kg/day, respectively. The regeneration rate was 2.5 times as high as the release rate in DIN, and 1.2 times in DIP. The results of mass balance calculation showed not only the nutrients released from the sediments but the nutrients regenerated in water column to be important in the control and management of water quality in Masan Bay.