• Journal of Korea Water Resources Association
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• v.46 no.10
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• pp.989-995
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• 2013

This study attempts to estimate the benefits of environmentally-enhancing water ensuing from Sangkwan multi-purpose reservoir. To this end, we apply a survey technique, the contingent valuation (CV) method to elicit the public willingness to pay (WTP). Two CV surveys of randomly selected households were administrated to on-site and off-site areas. As it happens, a number of respondents reported zero WTPs for the environmentally- enhancing water. To deal with the zero WTPs, this study employs a spike model. The results show that average household's WTP for the environmentally-enhancing water ensuing from Sangkwan multi-purpose reservoir is estimated to be 1,393.7 won for on-site area and 2,237.7 won for off-site area per year. The benefits of environmentally-enhancing water ensuing from Sangkwan multi-purpose reservoir amount to about 38.3 billion won per year. Our findings are expected to contribute to determining an appropriate level of investment and making management policies with regard to the benefits of environmentally-enhancing water.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.37-49
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• 2002

The application of conventional method for optimizing firm water supply and hydro-electric power generation has some limitation during abnormal or extreme drought periods. Hashimoto et al. (1982) suggested there risk evaluation criteria such as reliability, resilience, and vulnerability. These three criteria have been incorporated into a mixed-integer programming model for evaluating the possible performance of water- supply reservoir (Moy et al., 1986; Srinivasan et al., 1999). However, till now, these kind of researches have been conducted only for water-supply reservoir. Therefore there have been no other study for multi-purpose dam including hydro-electric power generation. This study presents an improved formulation of the previous model for evaluating a multi-purpose reservoir system operation considering water supply and hydro-electric power generation. The modified model was applied to the Daechung multi-purpose reservoir system in the Keum river basin to demonstrate the efficiency of the improved formulation.

• Journal of Korea Water Resources Association
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• v.42 no.3
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• pp.259-270
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• 2009

The applicability of the developed distributed rainfall runoff model using a multi-directional flow allocation algorithm and a real-time updating algorithm was evaluated. The rainfall runoff processes were simulated for the events of the Andong dam basin and the Namgang dam basin using raingauge network data and weather radar rainfall data, respectively. Model parameters of the basins were estimated using previous storm event then those parameters were applied to a current storm event. The physical propriety of the multi-directional flow allocation algorithm for flow routing was validated by presenting the result of flow grouping for the Andong dam basin. Results demonstrated that the developed model has efficiency of simulation time with maintaining accuracy by applying the multi-directional flow allocation algorithm and it can obtain more accurate results by applying the real-time updating algorithm. In this study, we demonstrated the applicability of a distributed rainfall runoff model for the advanced basin-wide flood management.

• Korean Journal of Remote Sensing
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• v.21 no.2
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• pp.145-162
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• 2005

To improve the accuracy of land-cover discrimination in SAB data classification, this paper presents a methodology that includes feature extraction and fusion steps with multi-temporal SAR data. Three features including average backscattering coefficient, temporal variability and coherence are extracted from multi-temporal SAR data by considering the temporal behaviors of backscattering characteristics of SAR sensors. Dempster-Shafer theory of evidence(D-S theory) and fuzzy logic are applied to effectively integrate those features. Especially, a feature-driven heuristic approach to mass function assignment in D-S theory is applied and various fuzzy combination operators are tested in fuzzy logic fusion. As experimental results on a multi-temporal Radarsat-1 data set, the features considered in this paper could provide complementary information and thus effectively discriminated water, paddy and urban areas. However, it was difficult to discriminate forest and dry fields. From an information fusion methodological point of view, the D-S theory and fuzzy combination operators except the fuzzy Max and Algebraic Sum operators showed similar land-cover accuracy statistics.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.59-70
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• 2022

Water distribution systems (WDSs) are a representative infrastructure injecting chlorine to disinfect the pathogenic microorganisms and supplying water from sources to consumers. Also, WDSs prescribe to maintain the usual standard (0.1-4.0 mg/L) of residual chlorine. However, the user's usage pattern, water age, network shape, and type affect the hydraulic features (i.e. nodal pressure, pipe velocity) and water quality features (i.e., the residual chlorine concentration). Therefore, this study developed an optimization approach for optimizing WDSs considering water quality-hydraulic factors using Multi-objective Harmony Search (MOHS). The design cost and the system resilience were applied as the design objective functions, and the nodal pressure and the concentration of residual chlorine are used as constraints. The derived optimal designs through this approach were analyzed according to network characteristics such as the network shapes and type. These optimal designs can meet the safety of economic and water quality aspects to increase user acceptance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.267-275
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• 2023

The cement industry has been contributing to solve the wastes problem by using various combustible wastes as alternative fuel to replace natural coal. To use more alternative fuels such as waste plastics, in the cement manufacturing process, it is necessary to stably burn alternative fuels and reduce air emissions such as NOx. This study is a case study on the multi-stage combustion calciner process, which is a technology that decreases the amount of NOx while increasing the use of alternative fuels. This study is a case study on the multi-stage combustion process, a technology that reduces the amount of harmful air emissions such as NOx while increasing the use of alternative fuels. Along results of comparing before and after applying the technology to actual cement manufacturing facilities, the amount of coal consumption decreased by 38 %, waste plastics consumption increased by 122 %, and NOx emissions decreased by 17 %. Results show that increasing the use of alternative fuels and reducing NOx emissions by multi-stage combustion is effective.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1188-1191
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• 1998

Detailed estimation of subsurface resistivity distribution and accurate estimation of actual fault current coming into the grounding system are indispensible to optimun grounding system design. Especially, it is essential for efficient grounding design to estimate subsurface resistivity distribution quantitatively and logically. Accurate estimation of subsurface resistivity distribution has an absolute influence on calculating touch voltage, step voltage and ground potential rise (GPR) which are related with grounding design standard for human safety. In this study, thirty-three electrical sounding surveys were made in Yongdam Power Station to obtain detailed subsurface resistivity distribution and the sounding data were interpreted quantitatively using multi-layered model. The results of the quantitative resistivity models were adopted practically to calculate grounding resistance values. Analytical asymptotic equations and CDEGS program were used in grounding resistance calculation and the results were compared and reviewed in the study.

• International Journal of Knowledge Content Development & Technology
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• v.12 no.1
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• pp.49-65
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• 2022

This study examined e-resources usage among polytechnic students in Southwest Nigeria. A descriptive research design was adopted for this study and the population consisted of polytechnic students from The Polytechnic, Ibadan and Federal Polytechnic, Ede. There were 9671 students from both polytechnics. A multi-stage sampling technique was employed with a sample fraction of 5% was drawn from the total number of students in each faculty amounting to 381. A structured questionnaire was the major instrument used for data collection and the questionnaire was pre-tested using Cronbach-alpha to determine the reliability co-efficient. Data obtained was analyzed using SPSS. The study found that the students from both polytechnics are aware of the e-resources and that the e-resources were mainly used for research, class assignment and to update knowledge. The problem such as epileptic power supply, poor internet connection and so on was identified. The study concluded that polytechnic students could benefit immensely from the enormous usage of e-resources particularly for teaching, learning and research. Based on the findings, recommendations were made.

• IE interfaces
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• v.16 no.4
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• pp.485-495
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• 2003

This paper reports on the application of the integration of mathematical programming model and database in a decision support system (DSS) for the planning of the multi-reservoir operating system. The DSS is based on a multi-objective, mixed-integer goal programming (MIGP) model, which can generate efficient solutions via the weighted-sums method (WSM). The major concern of this study is seamless, efficient integration between the mathematical model and the database, because there are significant differences in structure and content between the data for a mathematical model and the data for a conventional database application. In order to load the external optimization results on the database, we developed a systematic way of naming variable/constraint so that a rapid identification of variables/constraints is possible. An efficient database structure for planning of the multi-reservoir operating system is presented by taking advantage of the naming convention of the variable/constraint.

• Journal of KIISE:Software and Applications
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• v.31 no.8
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• pp.969-979
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• 2004

Recently, large-scale enterprise information systems are commonly based on the multi-tiered middleware or frameworks to support such requirements as functional reuse, heterogeneous system resources, and multiple platforms. However, these multi-tiered or distributed multi-platform architecture incurs the interoperability issue of the components and metadata among the middleware. This paper introduces the Simple Object Application Framework (SOAF) which supports heterogeneous resources and platform-independent component-based development, with the abstract programming style of the object-oriented frameworks and the XML-SOAP based component persistence mechanism.