• Fisheries and Aquatic Sciences
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• v.12 no.2
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• pp.118-129
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• 2009

To develop a sustainable management model for oyster farming in Pukman Bay, Korea, we estimated the carrying capacity for oyster farming using food availability data. Optimal culture densities were calculated to be 124-133 individuals per unit flux area ($m^2$) and 310-330 individuals per string. The present annual production is approximately 1,038 tons/year, which is 87% of the estimated maximum yield of 1,193 tons/year. Therefore, considering annual fluctuations and a critical buffer to reduce ecological impacts, the current level is within optimal conditions. During periods of increased water temperature, energy demand was largely met by high primary production. The food supply significantly decreased as the harvest season approached, and 10 out of 21 oyster farms had a deficient food supply for at least 1 month. Therefore, these farms (39% of the farms within the bay) exceeded optimal densities.

• Journal of Korean Society of Rural Planning
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• v.22 no.1
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• pp.13-23
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• 2016

There is a need to analyze unconfined groundwater behavior since the demand of groundwater use has been increasing. While unconfined groundwater temperature is tend to be affected by air temperature, it is hard to find an empirical study in South Korea. In this research, we try to determine the relationship between daily average air temperature and daily average groundwater temperature by time-sequential analysis of groundwater monitoring wells in Galshin basin in Yesan-Gun, Chungcheongnam-Do. In addition, models to estimate groundwater temperature from air temperature were developed. In this research 101-day moving average method with measured air temperature is used to estimate groundwater temperature. To verify the developed model, estimated values of average groundwater temperature with 101 moving average are compared to the measured data from September 10 2007 to September 9 2008. And, Nash-Stucliff Efficiency and Coefficient of Determination were 0.970 and 0.976, therefore it was concluded that the model allowing groundwater temperature estimation from air temperature is with reasonable applicability.

• Analytical Science and Technology
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• v.8 no.2
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• pp.167-170
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• 1995

A simple and rapid permanganate value test procedure for the estimation of COD, based on the photometric measurement of the remained permanganate after the color bleaching by oxygen demand organics during digestion, has been described. Optimized conditions were 1% NaOH, 0.6mM $KMnO_4$, with a closed reflux in the boiling water bath for 90 sec using sample size of 5mL.

• Analytical Science and Technology
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• v.8 no.3
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• pp.335-340
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• 1995

Automatic biochemical oxygen demand(BOD) measurement system has heen developed using a microbial membrane electrode, prepared from Bacillus subtilis and polyvinyl alcohol(PVA). The automatic BOD measurement system showed a linear response curve up to BOD 60 ppm using a glucose/glutamic acid standard solution, and all the BOD measurement processes are carried out automatically to calculate BOD whithin 10 min after each sample injection. The response times of the microbial electrode was 5 minutes with a 5 min recovery time between measurements and the relative error of the BOD estimation was within 10%.

• Land and Housing Review
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• v.1 no.1
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• pp.27-34
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• 2010

The energy consumption of residential sectors is given a sizable portion in total energy consumption. So, improvement of building performance can be as a part of principal energy strategy. For this reason, an evaluation tool for estimation of energy consumption was developed and supportive policies were considered in this study. In particular, energy saving technology were examined to practice the green home project, among them 7 items were selected as a factor for estimating energy consumption. In addition, to the simulation study on energy consumption, heating load, hot water demand and electric consumption was also studied with actual measured value. Further more, several supportive policies were discussed to encourage green home project in Korea.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.367-374
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• 2013

Underground infrastructure systems provide essential public services and goods through buried structures including water and sewer, gas and petroleum, power and communication pipelines. The majority of existing underground infrastructure systems was installed in green field areas prior to development of complex urban built environments. Currently, there is a global trend to escalate major demand for underground infrastructure system renewal and new installation while minimizing disruption and maintaining functions of existing superstructures. Therefore, Engineers and utility owners are rigorously seeking technologies that minimize environmental, social, and economic impact during the renewal and installation process. Trenchless technologies have proven to be socially less disruptive, more environmentally friendly, energy conservative and economically viable alternative methods. All of those benefits are adequate to enhance overall sustainability. This paper describes effective sustainable solutions using trenchless technologies. Sustainability is assessed by a comparison between conventional open cut and trenchless technology methods. Sustainability analysis is based on a broad perspective combining the three main aspects of sustainability: economic; environmental; and social. Economic includes construction cost, benefit, and social cost analysis. Environmental includes emission estimation and environmental quality impact study. Social includes various social impacts on an urban area. This paper summarizes sustainable trenchless technology solutions and presents a sustainable construction method selection process in a proposed framework to be used in urban underground infrastructure capital improvement projects.

• Environmental and Resource Economics Review
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• v.33 no.2
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• pp.159-178
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• 2024

This study aims to assess the direct and indirect impacts of local fiscal expenditures on water quality. Panel data spanning from 2010 to 2018 for 173 cities and districts in Korea are assembled, and a two-stage dynamic panel model is utilized for our estimation. The empirical findings reveal several key insights. Firstly, local fiscal expenditures on water quality are effective in ameliorating both Biological Oxygen Demand (BOD) and Total Phosphorus (T-P). Notably, the direct impact on T-P surpasses that on BOD in the short and long run. Secondly, expenditures dedicated to water quality improvement demonstrate a positive effect on local economic growth, and an inverted U-shaped relationship is observed between BOD and local economic growth. Due to the positive linkage, the indirect effect on BOD suggests, on average, a deterioration in water quality during local economic growth. Thirdly, concerning BOD, the direct effect of government expenditure on water quality improvement outweighs the indirect effect, but in the case of T-P, the indirect effect is not significant, and the total effect is solely determined by the direct impact. Despite local fiscal expenditures potentially exacerbating water quality through regional economic growth, the study finds that the direct enhancement of water quality remains a more substantial factor in the short and long run.

• Journal of Korea Water Resources Association
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• v.32 no.3
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• pp.281-289
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• 1999

Small-scale hydropower projects at existing agricultural reservoirs can contribute to produce electric energy by maximizing the use of releases from the reservoirs. The irrigation water duration, the reservoir hydropower simulation, and the nonlinear programming model are employed to estimate potential hydroelectric energy at an existing reservoir. The nonlinear programming model consists of finding a maximum hydroelectric energy subject to irrigation water demand constraints. The sample reservoir given a set of inflow and irrigation water is considered. The optimal solutions by the optimization model yield the most hydroelectric energy for the analysis period in the three methods. Consequently, the nonlinear programming model uses the most water for hydropower generation with respect to the total inflow of the sample reservoir. It is also found that additional storage by increasing the normal water level of the sample reservoir does not significantly increase the annual hydroelectric energy for the given reservoir. It is expected that the optimization model and the proposed procedure for estimating potential hydroelectric energy can be applied to evaluate feasibility analysis for small scale hydropower additions at existing agricultural dams.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.176-185
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• 1998

For the sustainable production of cultured arkshell Scapharca broughtonii and pre-estimation of the harvest of it, we investigated the relationship between the habitat environmental factors and the physiological conditions of the arkshell in the two experiment sites near the Chinhae Bay, Korea. For the analysis of habitat environmental factors such as temperature, salinity, dissolved oxygen, DIP (dissolved inorganic phosphate), DIN (dissolved inorganic nitrogen), suspended solids and chlorophyll a of bottom water and T-S (total sulfide) and COD (chemical oxygen demand) of surface sediment were measured, To determine physiolosical condition of cultured arkshell, shell length, fatness, glycogen, hemoglobin content and gametogenesis were examined. Water temperature were higher in Woongchon than in Songdo in 1992, and were Higher in Songdo in 1993. Salinity were higher in Songdo than in Woongchon except from January to May in 1992. COD, suspended solids and chlorophyll a content were higher in Songdo than in Woongchon, while the contents of sediment sulfide, DO, DIP and DIN were higher in Woongchon. Based on the environmental assessment, significant factors affecting the growth and physiological condition of arkshell were quantity of food and total sulfide content in the bottom sediment.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.73-80
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• 2010

The optimal design of water distribution system have started with the least cost design of single objective function using fixed hydraulic variables, eg. fixed water demand and pipe roughness. However, more adequate design is accomplished with considering uncertainties laid on water distribution system such as uncertain future water demands, resulting in successful estimation of real network's behaviors. So, many researchers have suggested a variety of approaches to consider uncertainties in water distribution system using uncertainties quantification methods and the optimal design of multi-objective function is also studied. This paper suggests the new approach of a multi-objective optimization seeking the minimum cost and maximum robustness of the network based on two uncertain variables, nodal demands and pipe roughness uncertainties. Total design procedure consists of two folds: least cost design and final optimal design under uncertainties. The uncertainties of demands and roughness are considered with Latin Hypercube sampling technique with beta probability density functions and multi-objective genetic algorithms (MOGA) is used for the optimization process. The suggested approach is tested in a case study of real network named the New York Tunnels and the applicability of new approach is checked. As the computation time passes, we can check that initial populations, one solution of solutions of multi-objective genetic algorithm, spread to lower right section on the solution space and yield Pareto Optimum solutions building Pareto Front.