• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.419-424
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• 2007

According to increase of consumer's desire for clean tap water, advanced treatment processes include with membrane, ozone, and granular activated carbon(GAC) were introduced. In order to evaluate the effect of advanced treatment processes for residual chlorine decay and trihalomethane(THM) formation in water distribution system, dissolved organic matter(DOC) removal of each advanced treatment process was investigated. The residual chlorine decay and THM formation using bottle tests were also evaluated. $UV_{254}$ removal in all advanced treatment was better than DOC removal. Especially, DOC by ozone treated was removed as 4% in contrast with sand filtered water, but $UV_{254}$ was removed about 17%. This result might be due to convert from hydrophobic DOC to hydrophilic DOC by ozonation. Ozone/GAC process was most effective process for DOC removal. The residual chlorine decay constants in treated water by sand filtration, ozonation, GAC adsorption, and ozone/GAC processes were 0.0230, 0.0307, 0.0117 and 0.0098 $hr^{-1}$, respectively. The sand filtered water was produced 81.8 ${\mu}g/L$ of THM after 190 hours of reaction time, as the treated water by ozone, GAC, and Ozone/GAC was less produced 6.0, 26.2, 30.3% in contrast with sand filtered water, respectively. Consequently, the durability of residual chlorine and reduction of THM formation were improved by advanced treatment processes.

• Environmental Engineering Research
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• v.23 no.1
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• pp.99-106
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• 2018

Lack of information on the Biochemical Oxygen Demand (BOD) decay rates of river water under the tropical environment has triggered this study with an aim to fill the gap. Raw sewage, treated sewage, river water and tap water were mixed in different proportions to represent river water receiving varying amounts and types of wastewater and fed in a laboratory flume in batch mode. Water samples were recirculated in the flume for 30 h and BOD and Carbonaceous BOD (CBOD) concentrations were measured at least six times. Decay rates were obtained by fitting the measured data in the first order kinetic equation. After conducting 12 experiments, the range of BOD and CBOD decay rates were found to be 0.191 to 0.92 per day and 0.107 to 0.875 per day, respectively. Median decay rates were 0.344 and 0.258 per day for BOD and CBOD, respectively, which are slightly higher than the reported values in literatures. A relationship between CBOD decay rate and BOD decay rate is proposed as $k_{CBOD}=0.8642_{k_{BOD}}-0.0349$ where, $k_{CBOD}$ is CBOD decay rate and $k_{BOD}$ is BOD decay rate. The equation can be useful to extrapolate either of the decay rates when any of the rates is unknown.

• Journal of Korea Water Resources Association
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• v.43 no.1
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• pp.95-104
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• 2010

The tap water supply in Korea mainly depends on the surface water. However, the advanced water purification process becomes a necessity due to the deterioration of surface water quality and the risk of accidental spill. High cost of water treatment and public concerns make the decision makers turn to riverbank filtration as an alternative to the surface water. Riverbank filtration has been employed for water supply in many developed countries for more than 150 years. In Korea, riverbank filtration has drawn attention since 1990s as a supply source having potential to stably meet the ever-increasing water demand. Some cities located in the Nakdong River Basin are currently supplying water through riverbank filtration. This work studies the site suitability analysis for riverbank filtration using game theory. Theory of games, which is a branch of applied mathematics used in social sciences (most notably economics), biology, engineering and computer science, was applied to candidate locations for the selection of riverbank filtration site. We proposed a policy game model as a new method adopting a probabilistic approach. The model developed turned out to be an effective tool for site selection.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.175-183
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• 1998

Yulmoo Mul-kimchi was prepared by fermentation of the mixture of 1 part of leafy radish and 2.75 parts of water. It is thought that during the kimchi fermentation both the biosynthesis and destruction of ascorbic acid occurred at the same time. So the ascorbic acid content in Kimchi broth was strongly influenced by the environment of the processing period. In the present studies, an attempt had been made to elucidate the effect of water quality on the content of ascorbic acid and the population change of microorganism during Mul-kimchi fermentation. Five kinds of water such as tap water, an underground water, one commercially available processed water, distilled water and triply distilled water were examined. Nevertheless there were no differences in the population of microorganism and the pattern of acid formation among the five different kind of waters, a large variation of ascorbic acid content was observed. The ascorbic acid content of Kimchi prepared with triply distilled water showed the highest of 7.2 mg% in contrast to 3.37 mg% in tap water kimchi, and 5.72 mg% in the kimchi using underground water which has relatively high concentration of Ca. These results suggested that pure water free of metal ions might prevent the destruction of ascorbic acid during the fermentation. The considerable amount of ascorbic acid in the Kimchi with underground water might be due to Ca ion in the water.

• Journal of Fisheries and Marine Sciences Education
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• v.15 no.1
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• pp.115-122
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• 2003

Generally, material for radiator of automobile is composed of Al-alloy, but part of radiator material is still composed of Cu. Specially, Al-alloy replaces Cu and Cu-alloy as cooling and heating system material for light weight. Therefore, galvanic electronic cell is formed between Al-alloy and Cu for automobile radiator material, and Al-alloy corrosion is accelerated. So, in this study, galvanic corrosion test of Al-alloy coupling with Cu was carried out in distilled water, tap water, polluted environment and non-freezing solution. And thus corrosion potential and galvanic currrent density of Al-alloy coupling with Cu is investigated.

• Computers and Concrete
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• v.21 no.4
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• pp.367-376
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• 2018

This study reports the results of nondestructive monitoring of macro void developments in mortars manufactured with both ordinary Portland cement and sulfate resistant cement. Two types of curing were utilized; tap water curing and another curing environment that contains 5% $Na_2(SO_4)$ solution. Being the primary objective of this study, macro void developments of the mortar specimens were monitored by X-ray Medical Computerized Tomography. Compressive strength tests and water absorption tests were conducted on specimens that were kept in both curing environments for a duration of 560 days. Data analyses yielded consistent results among the three tests used in this experimental study. Macro void ratios of mortars decreased at the beginning of experiments for a certain period; afterwards, macro void ratios increased. The objective of this study was accomplished as anticipated since X-CT image analysis was able to nondestructively monitor macro void development process in cement mortars.

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.192-196
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• 2003

Objective of this study was to investigate the influences of harvest index and percolation water quality as irrigated the discharge waters from an industrial and a municipal wastewater treatment plants and seawater (1:5 seawater: tap water) as alternative water resources during tillering stage for drought stress. There were four different treatments such as the discharge water from an industrial (textile dyeing manufacture plant) wastewater treatment plant (DIWT), discharge water from the municipal wastewater treatment plant (DMWT), seawater (1:5) and groundwater as a control. For the initial chemical compositions of alternative waters, it appeared that higher concentrations of COD, $Mn^{2+}$, and $Ni^+$ in DIWT were observed than reused criteria of other country for irrigation, and concentrations of $EC_i$, Cl, and $SO_4$ in seawater were higher than that for irrigation. Harvest index was not significantly different between DIWT and DMWT with different irrigation periods in two soil types, but that of seawater (1:5) is decreased with irrigation periods in clay loam soil and not different between 10 days and 20 days of irrigation periods in sandy loam soil. For percolation water qualities, values of sodium adsorption ratio (SAR) are increased with prolonging the irrigation periods of seawater (1:5) and DIWT, but those of DMWT were almost constant through the cultivation periods regardless of the irrigation period in both soil types. EG of percolation waters is eventually increased with prolonging days after irrigation regardless of irrigation periods in both soil types. Therefore, it might be concluded that there was potentially safe to irrigate the discharge water from municipal wastewater treatment plant relative to harvest index, SAR and $EC_i$ values of the ground water through the rice cultivation period at tillering stage for drought period.

• Korean Journal of Poultry Science
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• v.47 no.3
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• pp.121-126
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• 2020

This study was conducted to investigate the effect of drinking ion water on the performance, egg quality, and serum biochemical properties of laying hens in a high-temperature environment. A total of 180 laying hens with equal egg production rates were randomly divided into three treatments with five replicates. Treatments were applied from 24 to 27 weeks of age and included the supply of ion water (IW), tap water (TW), and cold water (CW). The results showed that the egg production rate, egg weight, and feed intake of hens were significantly (P<0.01) improved in the IW group compared with those in the TW group but did not differ from those in the CW group. Egg quality parameters such as albumen height, Haugh unit, and eggshell thickness were found to be higher in the IW than in the TW group (P<0.05); however, no significant differences were observed in comparison with the CW group. Serum Ca and P concentrations tended to increase (P<0.10) in the IW group, and serum high-density lipoprotein cholesterol and albumin levels were greater (P<0.05) in response to IW than those to TW. This study provides evidence that the supply of IW can relieve the high-temperature stress during the summer. In particular, because the improved effects of the IW were confirmed to be similar to those of CW, it shows potential as a method to manage the drinking water of hens in the summer season along with the supply of CW.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.2
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• pp.173-181
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• 2007

Recently, galvanizing method is predominantly being used not only a economical point of view but also due to it s stability and long life. For example, guard rail of high way, all kinds of structures for ship etc. were protected with galvanizing and demand of galvanized structural materials was being increased with more and more. However, galvanized structures were inevitably being deteriorated with time eventually because they were corroded with solution of galvanizing film and exfoliation of it s film in the present severe corrosive environment. Therefore, it is necessary to improve the corrosion resistance of the galvanizing film through various methods such as variation of chemical composition of galvanizing bath, chromate treatment and coating treatment. In this study, three test specimens such as pure galvanizing, galvarium, and chromate treatment were submerged at tap water with inhibitor addition. And the effect of their corrosion resistance improvement was comparatively investigated with electrochemical method. Corrosion current density of the galvanized steel was the largest among three specimens, however, the galvarium steel showed the lowest corrosion current density. Futhermore, these three kinds of test specimens indicated considerably excellent corrosion resistance by dipped at tap water with inhibitor addition. Especially, the galvanized steel showed the best effect of corrosion resistance improvement than other test specimens.

• Industry Promotion Research
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• v.1 no.1
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• pp.129-135
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• 2016

This study verified the water saving effect in case of raising water rate depends on water rate awareness. The study results showed that the perceived appropriacy of government aid(p<.001), home water rate(p<.01), water rate pricing system, water rate, water rate diffrences depend on use and area(p<.05) significantly affected the degree of agreement of raising water rate. Also, education, residence, member of household, occipation, monthly household income, monthly water rate significantly affected the degree of agreement of raising water rate, consumer behavior for saving water. This study provided implication for water rate pricing policy by analyzing the water saving effect in case of raising water rate depends on water rate awareness and revealing the determinants of the degree of agreement of raising water rate.