• Korean Journal of Ecology and Environment
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• v.42 no.4
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• pp.452-464
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• 2009

The objectives of this study were to evaluate spatial and temporal variability of water quality in 10 reservoirs and identify the key nutrients (N, P) influencing chlorophyll-a (CHL) along with analysis of empirical models and zonal patterns of total phosphorus (TP) and CHL. We analyzed total nitrogen (TN), TP, CHL, water clarity (Secchi depth, SD), and evaluated potential limiting nutrient using ambient N:P ratios and previous criteria of ambient nutrients. Water clarity and CHL varied largely depending on the seasonal monsoon and type of reservoir, but trophic state was diagnosed as eutrophy, base on mean CHL in most reservoirs. The peak of TP did not match the contents of CHL due to rapid flushing during the high run-off period. In the reservoir of DR, regression coefficient in the $P_r$ was 0.510 but was 0.159 in the $M_o$, while the TP-CHL relation in the YR increased during the monsoon compared to the premonsoon. The regression coefficient in the $P_r$ was not statistically significant but the value of $M_o$ was 0.250. TP showed similar longitudinal zonal gradients among the reservoirs of DR, YR and JR. Empirical models of TP-CHL, based on overall data, showed that CHL was determined by phosphorus($R^2=0.244$, p=0.0019). Regression analysis of CHL-SD showed a stronger linear fit ($R^2=0.638$, p<0.001) than the TP-CHL model.

• Journal of the Korean Society of Food Culture
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• v.11 no.5
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• pp.683-687
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• 1996

Jujube paste was prepared by autoclaving the fresh jujube at 1.2 atm and $120^{\circ}C$ for 30 min and removing the skin and cores. In order to increase the juice yield, the paste was treated with pectinase, cellulase and their combinations. The soluble fractions of enzymatically treated jujube paste were characterized in terms of yield, pH, titratable acidity, color, Bx, transmittance and sugar compositions. The original paste exhibited the water soluble fraction of 57.3%. Of various quality factors, the clarity was the most significantly distinguished between pectinase and cellulase treatments. The cellulase treatment produced the cloudy juice with the yield of 83.60%. On the other hand, the clear juice was produced by the pectinase and combined treatments due to degradation of pectins, whose yields were 79.47% and 85.39%, respectively. The results clearly demonstrated that the pectinase treatments improved the solubilization efficiency and clarity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.18 no.1
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• pp.132-149
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• 1992

This study relates to a microemulsion gel which is applied in various cosmetic preparations because of good appearance, superior stability and a thin, uniform, non-greasy fi Am on the skin. Main object of this study is to elucidate the influence of polyol(clarifying agent and/or coupling agent in microemulsion) on microemulsion and to establish the optimum conditions for microemulsion gel formation in the view of superior consistency, stability, clarity and pick-up from a container. The constituents of the system are composed of water, polar ester oi1, nonionic surfactant and polyol. Using the three-component phase diagram and the tetrahedral-phase diagram, we have investigated the changes of transparence regions, consistency and resonance effect by an impact in microemulsion gel varying in polyol ratio. The results of this study showed that the variation in the content of water and couple ins agent has major influence on the microemulsion gel and the optimum formation region of microemulsion gel is the widest when the ratio of glycerine(coupling agent) to water is 63-75% It is believed that optimum use of polyol seems to be helpful to obtain the microemulsion gel containing maximum amount of oil phase with minimum amount of surfactant which is recently one of the major problems of cosmetic chemists.

• Journal of Environmental Health Sciences
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• v.19 no.2
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• pp.1-9
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• 1993

In public water supply systems, Alum and/or PAC being used as a coagulant. It is well known that their use increased frequently the concentration of residual aluminum in filtered water upon operating conditions. This study was conducted to find the optimum conditions that both the concentration of residual aluminum and turbidity are minimized by changing such factors as pH, temperature, alum dosage, mixing rate, alkalinity and hardness. The results can be summarized as follows: The pH values for the minimum concentration of residual aluminum and turbidity as a given experimental condition were found at pH 6 and pH 7 respectively, the apparent clarity was best at pH 8. The floc settling rate was the greatest at pH 6.5, but the turbidity was high at the same condition. The more alum dosage, the higher the concentration of residual aluminum. However the alum dosage less than 15 mg/l tend to decrease in turbidity. Restabilization and enmeshment occurred near 15 mg/l and 20 mg/l of alum dose respectively. With the increase of mixing rate (rapid and slow), the concentration of residual aluminum and turbidity are increased and the same trend was found in increment of mixing time. At low water temperature, the concentration of residual aluminum was decreased, but turbidity was increased. It was confirmed that alkalinity had an effect on the coagulation efficiency, but hardness did not.

• Journal of Aquaculture
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• v.21 no.3
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• pp.181-183
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• 2008

It has been a very hard problem to reduce solids especially suspended solids (SS) in recirculating aquaculture systems. Present description is based on the performance of trapping SS by the biofilter of Intensive Bio-production Korean (IBK) system which is originally developed for nitrification. We found out that this filter has an excellent capability to remove SS in addition to nitrification. Filter element used here is corrugated plastic roofing plates readily available in the market, and cheaper than specially developed and patented products. It is easy to maintain the system, and requires low power consumption to operate for the treatment of a large amount of water. With 2 pumps of 5 hp each, about 500 $m^3$ of water is treated per hour. Flow speed in the filter was 2.6 mm/sec on average. This low flow speed and very large amount of water treated are the reasons for very effective trapping of fine SS. Upon single pass through this filter, 74.5% of total SS and 40% of non-settleable SS were removed. Wherever this filter is employed in recirculating fish farms water keeps high clarity, this having also been empirically ascertained.

• Journal of Korean Society on Water Environment
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• v.38 no.4
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• pp.177-189
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• 2022

Nature-based Solutions (NbS) are defined as practical and technical approaches to restoring functioning ecosystems and biodiversity as a means to address socio-environmental challenges and provide human-nature co-benefits. This study reviews NbS-related literature to identify its key characteristics, techniques, and challenges for its application in climate-adaptive water management. The review finds that NbS has been commonly used as an umbrella term incorporating a wide range of existing ecosystem-based approaches such as low-impact development (LID), best management practices (BMP), forest landscape restoration (FLR), and blue-green infrastructure (BGI), rather than being a uniquely-situated practice. Its technical form and operation can vary significantly depending on the spatial scale (small versus large), objective (mitigation, adaptation, naturalization), and problem (water supply, quality, flooding). Commonly cited techniques include green spaces, permeable surfaces, wetlands, infiltration ponds, and riparian buffers in urban sites, while afforestation, floodplain restoration, and reed beds appear common in non- and less-urban settings. There is a greater lack of operational clarity for large-scale NbS than for small-scale NbS in urban areas. NbS can be a powerful tool that enables an integrated and coordinated action embracing not only water management, but also microclimate moderation, ecosystem conservation, and emissions reduction. This study points out the importance of developing decision-making guidelines that can inform practitioners of the selection, operation, and evaluation of NbS for specific sites. The absence of this framework is one of the obstacles to mainstreaming NbS for water management. More case studies are needed for empirical assessment of NbS.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.1-6
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• 2016

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating ($1000^{\circ}C$ for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and carbonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. $CO_2$ implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.275-279
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• 1977

During the experimental rearing period of common carp in a small simple recirculating aquarium combined with frequent exchanges of water and cleanings, some observations were made on the conditions of fish growing which was directly and instantly affected by the cleaning frequency of strainer, changing rate of water, division and frequency of feed supply, prohibition of excess feeding and the amount of dissolved oxygen. The fish don't seem to be stressed by the manipulation for the change of rearing water, cleaning of detritus in the strainer and filter. It appeared that the most hazzardous matters to fish growth were : 1) supplying feed when fish do not show active response to feed supplied, and 2) giving ample amount of feed at one time. When especially the amount of the feed is within the range fish instantly can swallow, the water clarity is maintained even after feeding operation, but if any excess amount is given the fish intake into mouth much more feed than able to instantly swallow and try to swallow it resulting in much dissolving and suspension of feed materials in water, making the water quite cloudy. Consequently all the water as well as filter bed becomes significantly polluted.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.19 no.2
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• pp.75-80
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• 2013

The physicochemical properties of the hydroxypropylated mung bean, sweet potato and water chestnut starches were studied. The blue value and amylose content of mung bean starch were higher than those of sweet potato and water chestnut. Pasting temperature of hydroxypropylated starches were lower than those of native starch and decreased with increasing contents of propylene oxide. Peak viscosity increased with the increase of degree of hydroxypropylation. With increasing contents of propylene oxide, the clarity and swelling power of all starches were increased and those of mung bean were higher. Mung bean starch produced better hard capsules than sweet potato and water chestnut starch. Hydroxypropylated (>6% propylene oxide) water chestnut starch-based capsules completely dissolved, but hydroxypropylated (>12% propylene oxide) mung bean and sweet potato starch-based capsules were dissolved within 10 min. These results showed that hydroxypropylated starch-based capsules have potentials for pharmaceutical applications as a substitute for gelatin hard capsules.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.827-830
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• 1997

Sensory evaluation method was used to develop a type jujube tea the organoleptic properties were evaluated with regard to the optimum sugar content, clarity, drinking temperature and fruit pulp content of the jujube tea. Clarified jujube tea extracted from 25% by weight of dry jujube fruits and 75% water was preferred to those from 15%, 20% and 30% jujube fruites although those from 20% and 30% were not significantly different at 5%level. In spite of the average acceptability score of cloudy jujube tea with 5% of added fruit pulp was not significantly different from that of clarified one, the more fruit pulp in the tea products the worse its acceptability. Cold jujube tea was preferred to warm and hot ones, but these were not significantly different.