• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.4
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• pp.218-237
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• 2018

The purpose of this study is to propose a mid - range low - orbit water disaster monitoring satellite development plan to revolutionize water disaster management infrastructure through securing an independent and leading observation infrastructure and to secure safety against disaster prepared for climate change. Water and water disaster satellites should be able to detect changes in the surface of the ground and observe hydrological factors during daytime, nighttime, and bad weather. In addition, independent technology development should be possible. To do this, we selected C-band image radar payload considering domestic technology and water resources management, and suggested detailed development plan. In this way, it is reflected in the national next-generation mid-satellite 2-phase project plan to secure the basis for building a disaster monitoring system related to wide-area water.

• Journal of Korea Water Resources Association
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• v.55 no.3
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• pp.217-227
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• 2022

Since China adopted Public-Private Partnerships (PPPs) in the water sector in the early 1990s, PPPs have played a key role in improving infrastructure development in China. As the Chinese water market became one of the most enormous and potential existing in the world, once a water player settles down in the market, the company tends to be the world-leading water player on the basis of the number of people served from water infrastructure. Unlike the early PPP period overwhelmed by several water transnational corporations, local water players began to dominate the domestic market and have recently expanded their influence overseas. The Chinese government has continuously intervened to promote private sector participation of local water players in the PPP development process in legal and institutional aspects. Thus this article examined the development of water PPPs in China and analyzed the successful elements of local water players' growth related to the government policy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.43-45
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• 2011

As technologies evolve, building large concrete structures ever built, but due to lack of maintenance after completion of concrete corrosion, leaks, and preparedness from the problem that is an urgent need. In particular, water-resistant variety of concrete structures. How the concept applies to the most important public drinking water purification and drinking water that is draining the production and storage, and distribution as the structure cause damage to the structure when the contaminated water is supplied to each home that can harm the health of citizens is the cause. Therefore, the correct choice of materials, and thorough a lot of investment in construction and maintenance should have. In this study, unlike conventional water-proof materials, methods, and in other reactions easily than conventional poly-urea resins have good physical performance and chemical resistance, high performance polyurea resin performance review of the physical infrastructure of the country for the longevity of would like to make long-term durability.

• Journal of Environmental Impact Assessment
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• v.18 no.6
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• pp.367-376
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• 2009

This paper proposes an application methodology of AHP(Analytic Hierarchy Process) based decision making theory for improvement priority by assessment of various risk factors affecting on deterioration of water supply systems, as major social infrastructure. AHP method is organized with three level of hierarchy which is introduced for multi-criteria decision making in this study. In the first level, assessment outputs are calculated by AHP for each affecting factor. In the second level, criteria are estimated by using assessment results with respect to structural and environmental factors. Consequently, ranking decision is performed in the third level. In order to present the effectiveness, a proposed method is compared with FCP(Fuzzy Composite Programming) for decision making. Since the results of the proposed method show better performance with consistent results, it can be applied as an efficient information for the determination for improvement priority of the study infrastructure.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.130-133
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• 2016

The increase in impervious surfaces due to urban development has caused a groundwater drawdown through the reduction of underground infiltration, flood disaster due to increased rainfall runoff and environmental pollution in higher pollutant concentrations of first flush rainwater. As an alternative to these problems, the needs of low impact development (LID) techniques is increasing in urban areas. In this study, the restoration efficiency of water cycle was assessed at a residential site development applied with the LID rainwater management system. The results of monitoring the water cycling showed that the efficiency of water cycle of LID rainwater management system was improved 41% more than that of conventional methods.

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.247-254
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• 2015

Changes in land-use type can affect soil and water properties in stream ecosystems. This study examined the effects of different land-use types on biogeochemical properties and microbial activities of a stream. We collected water and sediment samples in a stream at three different sites surrounded by varying land-use types; a forest, a radish field and a rice paddy. Nitrogen contents, such as nitrate, nitrite and total nitrogen in the stream water body, showed significant differences among the sampling sites. The highest nitrogen values were recorded at the site surrounded by cropland, as fertilizer runoff impacted the stream. Soil organic matter content in the sediment showed significant differences among sites, with the highest content exhibited at the forest mouth site. These differences might be due to the organic matter in surrounding terrestrial ecosystems. Microbial activities determined by extracellular enzyme activities showed similar values throughout all sites in the water body; however, the activities in the sediments exhibited the highest values near the forest site and mirrored the soil organic matter content values. From these results, we conclude that different land-use types are important factors affecting water and sediment properties in stream ecosystems.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.4
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• pp.67-74
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• 2016

Load Duration Curve (LDC) can be used as a method for load management of point and non-point pollution source because the LDC easily assesses the water quality corresponding to hydrological changes in a watershed. Recently, the application of LDC to total pollution load management is a growing interest in Korea. In this regard, A desktop-based LDC assessment system was developed in this study to provide convenience to users in water quality evaluation. The developed system can simply produce the LDC by using streamflow and water quality data involved in its database. Also, The system can quantitatively inform the success or failure of the achievement for a target water quality at monthly scale. Furthermore, seasonal water quality and point/non-point pollution load in a watershed can be estimated by this system. We expect that the developed system will contribute to establish local and national policies regarding water management and total pollution load management because of its advantages such as the pollution tracking investigation and the analysis of water quality and pollution loading amount in an ungauged watershed.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.487-490
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• 2003

Geumgang 2nd agricultural comprehensive development project is to develope the infrastructure in 43,000ha agricultural area. For this is the very large project, it is necessary to consider the plan of water use comprehensively. Therefore, watershed water balance model for this project has been developed and a variety of analysis has been carried out. And Geumgang Project Water Management System has been developed for the manager of irrigation facilities.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.910-918
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• 2010

In recent years, riparian buffer system has been known as one of the effective best management practices. However, establishment of riparian buffer system in aspect of plant species and its position in the riparian buffer zone has not been investigated due to lack of efficient evaluation method for the analysis of water quality improvement with established riparian buffer system. To solve this problem, the SWAT-REMM prototype was developed by the researchers in Canada. But, SWAT-REMM model can not consider the $NO_3-N$ load into riparian buffer system through subsurface flow. Thus to solved this problem, Fortran code of SWAT-REMM model was modified. This modified SWAT-REMM system was applied to the Bonggok watershed. Three riparian buffer scenarios, 15 m, 10 m, 5 m width for tree and grass, were made to evaluate the effects of riparian buffer system on water quality improvement. Reduction efficiency of T-N by riparian buffer system of 15 m wide was the greatest (6 ~ 37%, depending on subwatershed characteristics) among 3 scenarios. It indicates that the reduction efficiency of T-N load has increasing-tendency, as buffer width increasing. The results obtained from the analysis showed that wide buffer zones are found to be more effective in reducing non-point pollutant than narrow buffer zones in the riparian buffer zone system. Hence, the SWAT-REMM model could be efficiently used for evaluation and design the most effective riparian buffer systems to reduce pollutant loads to the watershed although many limitations still exist in SWAT-REMM model.