• Journal of Korea Water Resources Association
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• v.43 no.9
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• pp.769-780
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• 2010

Topological and hydraulic assessments to examine whether required demand and pressure are satisfied and using these assessed results as a criteria have been general methodology for reliability assessment of water distribution systems. However, many of existing studies that used nodal pressure calculated by hydraulic assessment for reliability assessment have two major issues to be solved. The one is that demand-driven analysis was used for hydraulic assessment and the other is that serviceability was not considered for reliability assessment. In addition, all of the studies used pressure-demand analysis which is suitable to hydraulic analysis for water distribution systems under abnormal operating condition considered only available nodal demand for reliability assessment. This means that advantages which can be obtained by pressure-driven analysis are not used properly and efficiently. In this study, new methodology for reliability assessment of water distribution systems using HSPDA model and distance measure method is suggested. This methodology considers both nodal pressure and nodal available demand for reliability assessment. Suggested methodology is applied to two water distribution systems to show its applicability and application results are compared with existing study.

• Culinary science and hospitality research
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• v.24 no.3
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• pp.104-112
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• 2018

The purpose of this study was to examine the quality characteristics of white pan bread according to the different types of water (tap water (still water), purified water, still water, light water, classical water, and bold water). Pan breads were statistically analyzed using texture profile analysis, fermentation, texture, suitability, image analysis, color, moisture content, and statistical analysis. This result will contribute to the commercialization of pan bread using various kinds of water. Ultimately, we analyzed the quality characteristics of various kinds of water, depending on the carbonic acid content on the dough and the pan bread, and to derive the optimum kinds and ratios of the water to be applied to the pan bread. As a result of the study, the best findings were obtained with water containing carbonic acid content more than the classical water according to overall characteristics, durability (Width of Tail and Integral), foot efficiency, softness, volume and preference check. Therefore, when white pan bread is produced by using water containing a carbonic acid content (5~7.5 mg/L) or more of the classical water, it affects the quality characteristics and a good obtains positive response to from consumers. In this study, the quality characteristics of pan bread based different kinds of water which were not available in the past, and the quality characteristics of pan bread, which can be used as the basic data for future research, were well analyzed.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.170-170
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• 2023

Providing safe and readily available water is vital to maintain public health. One of the most prevalent methods to prevent the spread of waterborne diseases is applying chlorine injection to the treated water before distribution. During the water transmission and distribution, the chlorine will experience a reduction, which can imply potential risks for human health if it falls below the minimum threshold. The ability to determine the appropriate initial intensity of chlorine at the source would be significant to prevent such problems. This study proposes two methods that integrate hydraulic and water quality modeling to determine the suitable intensity of chlorine to be injected into the source water to maintain the minimum chlorine concentration (e.g., 0.2 mg/l) at each demand node. The water quality modeling employs the first-order decay to estimate the rate of chlorine reduction in the water. The first method utilizes a backtracking algorithm to trace the path of water from the demand node to the source during each time step, which helps to accurately determine the travel time through each pipe and node and facilitate the computation of time-dependent chlorine decay in the water delivery process. However, as a backtracking algorithm is computationally intensive, this study also explores an alternative approach using a water age. This approach estimates the elapsed time of water delivery from the source to the demand node and calculate the time-dependent reduction of chlorine in the water. Finally, this study compares the outcomes of two approaches and determines the suitable and effective method for calculating the chlorine intensity at the source to maintain the minimum chlorine level at demand nodes.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.155-164
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• 2008

As popultations expand and economies develop, increasing competition for limited available water resources is occurring among many water users. This has brought greater attention to water allocation with legal and institutional constraints. This paper develops a optimal water allocation methodology to basinwide water resources allocation, which ensures that scare water resources are allocated among competing water users. The methodology need to be based on optimization technique to allocate water resources due to an extended scaled of river basin. The recommended model is developed to accomplish economic efficiency, equity and sustainability objectives. The appropriate case study is tested with various existing water right system allocation model and the recommended model. The result shows the applicability of model to the complex hydrologic system with legal and institutional constraints.

• Water for future
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• v.14 no.3
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• pp.55-66
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• 1981

The theory and practice of water quality scoring and indexing are introduced. The monthly water analysis data are available for six stations long the down-stream Han River whthin the areal boundary of the Special City of Seoul. The data cover the period between 1975 and 1979 inclusive and contain the analytical findings on 37 water constituents including DO, BOD, temperature, total solids and etc. Sic parameters are selected form the 37 items, that, to the judgement of the writer, best reflect the water quality of the Han River. They are; dissolved oxggen saturation, pH, fecal coliform, total solids, BOD and nitrate+ammonia. For each of the six parameters, a subscore function is developed and graphically presented to facilitate the transform of a measurment of the arameter to a subscore on a common score(e.G. 0-100) The score of a sample is calculated as a fuction of the six subscores, using four different approaches; (1) the unweighted arithmetic water quality score, (2) the weighted arithmetic water quality score, (3)the unweighted multiplicative score and (4) the reduced (total) score. Independent of these calculated scores, the experts' score which is calculated by averaging the ratings of water quality experts is obtained and compared with each of the four calculated scores by means of the least square method. The experts' score compares most favorably with the "reduced" score with the correlation coefficient of 0.956 : therefore this method of water quality scoring is adopted to calculate the Han River water quality scores and indices. Water quality index data for Guiri, ukdo, Pokwangdong, Noryangjin, Yongdungpo and Kayang Stations, 1975-1979 are as follow: The overall water quality index data of the Han River between Guiri and Kayang Stations are found; 47.3 in 1976, 48.0 in 1977, 48.5 in 1978 and 54.7 in 1979, indicating the general trend towards water quality improvent in this part of the river, in terms of the increased water quality index by average 1.85 points per year during this period. Finally the optimum sampling frequencies distributed among the six stations, using an equation which takes into account the coefficients of variation of the water quality scores and indices arec calculated.alculated.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.289-290
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• 2002

Stainless steel ball bearings are used in the control element drive mechanism and driving mechanisms such as step motor and gear boxes for the integral nuclear reactor, SMART. The bearings operate in pressurized pure water (primary coolant) at high temperature and should be lubricated with only this water because it is impossible to supply greases or any additional lubricant since the whole nuclear rector system should be perfectly sealed and the coolant cannot contain ingredients for bearing lubrication. Temperature of water changes from room temperature to about 120 degree Celsius and pressure rises up to 15MPa in the nuclear reactor. It can be anticipated that the frictional characteristics of the ball bearings changes according to the operating conditions, however little data are available in the literature. It is found that friction coefficient of 440C stainless steel itself does not change sharply according to temperature variation from the former research, and the friction coefficient is about 0.45 at low speed range. In this research frictional characteristics of the assembled ball bearings are investigated. A special tribometer is used to simulate the axial loading and the bearing operating conditions, temperature and pressure in the driving mechanism in the nuclear reactor. Highly purified water is used as lubricant ‘ and the water is heated up to 120 degree Celsius and pressurized to 15MPa. Friction force is monitored by the torque transducer.

• Environmental Engineering Research
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• v.18 no.3
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• pp.177-189
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• 2013

Studies were carried out on the speciation of heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr) during rotary drum composting of water hyacinth (Eichhornia crassipes) for a period of 20 days. Five different proportions of cattle manure, water hyacinth and sawdust were prepared for composting. This study concluded that, rotary drum was very efficient for the degradation of organic matter as well as for the reduction of mobility and bioavailability of heavy metals during water hyacinth composting. The results from the sequential extraction procedure of heavy metals shows that rotary drum composting changed the distribution of five fractions of Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr. The highest reduction in the bioavailability factors of Pb and Cd was observed during the process. The total concentration of Cu, Cr, and Cd was very low compared to the other metals (Zn, Mn, Fe, Ni, and Pb); however, the percentage of exchangeable and carbonate fractions of these metals was similar to other metals. These results confirmed that the bioavailability of metals does not depend on the total concentration of metals. From this study, it can be concluded that the addition of an appropriate proportion of cattle manure significantly reduced the mobile and easily available fractions (exchangeable and carbonate fractions) during water hyacinth composting in rotary drum.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.3
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• pp.15-25
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• 2005

Ninety tow percent of over 1,800 gate controlled dams in Korea are classified as small dams. The primary purpose of these small dams is to supply irrigation water. Therefore, while large dams can store as much as 80 percent of precipitation and thus are efficient to control flood, small dams are often lack of flood control function resulting in increased susceptibility drought and flood events. The purpose of this study is to develope a storage management model for irrigation dams occupying the largest portion of small dams. The proposed Storage Management Model (STMM) can be applied to the Seongju dam for efficient management. Besides, the operation standard is capable of analyzing additional available water, considering water demand and supply conditions of watershed realistically. And the model can improve the flood control capacity and water utilization efficiency by the flexible operation of storage space. Consequently, if the small dams are managed by the proposed Storage management model, it is possible to maximize water resources securance and minimize drought and flood damages.

• Advances in environmental research
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• v.2 no.1
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• pp.35-49
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• 2013

Research work on removal of fluoride from water, referred to as water defluoridation, has resulted into the development of a number of technologies over the years but they suffer from either cost or efficiency drawbacks. In this work, enhancement effects of phosphate and silicate on defluoridation of water by low-cost Plaster of Paris (calcined gypsum) were studied. To our knowledge, the influence of silicate on defluoridation was not reported. It was claimed, that the presence of some ions in the treated water samples, was decreasing the fluoride removal since these ions compete the fluoride ions on occupying the available adsorption sites, however, phosphate and silicate ions, from its sodium slats, have enhanced the fluoride % removal, hence, precipitation of calcium-fluoro compounds of these ions can be suggested. Percentage removal of $F^-$ by neat Plaster is 48%, the electrical conductance (EC) curve shows the typical curve of Plaster setting which begins at 20 min and finished at 30 min. The addition of phosphate and silicate ions enhances the removal of fluoride to high extent > 90%. Thermodynamics parameters showed spontaneous fluoride removal by neat Plaster and Plaster-silicate system. The percentage removal with time showed second-order reaction kinetics.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.311-325
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• 2017

Habitat suitability index (HSI) of 17 benthic macroinvertebrate taxa, which were lotic insects of generic category except Potamanthidae in mayfly, was developed for three physical habitat factors (current velocity, water depth and substrate) based on an ecological monitoring in a Korean stream (Gapyeong). Weibull model was used as a probability density function to analyze the distribution of individual abundance related with physical factors, which showed it was so available. Number of species and total individual abundance increased along with the increase of current velocity and the mean diameter of substrate, and decreased along with the increase of water depth. Most taxa showed a clear preference for a fast current velocity, shallow water depth and coarse substrate except Ephemera, Potamanthidae (mayfly), and Plectrocnemia (caddisfly) which were rheophobic, potamophilic and lithophobious. Based on the canonical correspondence analysis, the relative importance of each factor was determined as follows: current velocity > substrate > water depth.