• Journal of the Korean Society of Food Culture
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• v.7 no.4
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• pp.329-338
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• 1992

This study was attempted aimed to prepare of Andong sikhe by pure culture inoculation and to improve storage stability by the addition of stabilizers to the product. Lactobacillus delbreuckii was selected for pure culture inoculation in the fermentation. The effect of stabilizers on the sedimentation, sensory evaluation and viscosity of Sikhe were investigated during the fermentation of traditional Andong Sikhe stored at $4^{\circ}C$ Morphological characteristics of Sikhe were determined by scanning electromicrograpy. Among the stabilizers added to the traditional Andong sikhe Na-alginate was found to be best stabilizers. When the product was evaluated by the sensory panel, the addition of stabilizers up to 0.1% level actually increased the acceptability of the product, while the concentration of more than 0.2% stabilizers affected the acceptability of the negatively. Sikhe added Na-carboxymethyl cellulose and Na-alginate showed highest viscosity on the 2nd day of fermentation, while homogenized Andong sikhe with Carrageenan showed the highest peak in viscosity on the first day of fermentation. Lactic acid bacterial count reached to $3.2{\times}10^8/ml$ after 20 days of storage. The surface and cross section of rice was observed by scanning electron microscope. As the fermentation proceeded holes on the surface increased, and nearly empty cell wall remained at the later stage of fermentation. Use of pure cultured inoculum of L. delbreuckii supported the rapid build up of the lactic acid bacteria and consequently the whole process of the fermentation was shortened. The acceptability and product quality were improved by use of L. delbreuckii inoculum.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.377-388
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• 2022

Laboratory-scale experiments were performed to identify the As removal mechanism of the residual slag generated after the mineral carbonation process. The residual slags were manufactured from the steelmaking slag (blast oxygen furnace slag: BOF) through direct and indirect carbonation process. RDBOF (residual BOF after the direct carbonation) and RIBOF (residual BOF after the indirect carbonation) showed different physicochemical-structural characteristics compared with raw BOF such as chemical-mineralogical properties, the pH level of leachate and forming micropores on the surface of the slag. In batch experiment, 0.1 g of residual slag was added to 10 mL of As-solution (initial concentration: 203.6 mg/L) titrated at various pH levels. The RDBOF showed 99.3% of As removal efficiency at initial pH 1, while it sharply decreased with the increase of initial pH. As the initial pH of solution decreased, the dissolution of carbonate minerals covering the surface was accelerated, increasing the exposed area of Fe-oxide and promoting the adsorption of As-oxyanions on the RDBOF surface. Whereas, the As removal efficiency of RIBOF increased with the increase of initial pH levels, and it reached up to 70% at initial pH 10. Considering the PZC (point of zero charge) of the RIBOF (pH 4.5), it was hardly expected that the electrical adsorption of As-oxyanion on surface of the RIBOF at initial pH of 4-10. Nevertheless it was observed that As-oxyanion was linked to the Fe-oxide on the RIBOF surface by the cation bridge effect of divalent cations such as Ca²⁺, Mn²⁺, and Fe²⁺. The surface of RIBOF became stronger negatively charged, the cation bridge effect was more strictly enforced, and more As can be fixed on the RIBOF surface. However, the Ca-products start to precipitate on the surface at pH 10-11 or higher and they even prevent the surface adsorption of As-oxyanion by Fe-oxide. The TCLP test was performed to evaluate the stability of As fixed on the surface of the residual slag after the batch experiment. Results supported that RDBOF and RIBOF firmly fixed As over the wide pH levels, by considering their As desorption rate of less than 2%. From the results of this study, it was proved that both residual slags can be used as an eco-friendly and low-cost As remover with high As removal efficiency and high stability and they also overcome the pH increase in solution, which is the disadvantage of existing steelmaking slag as an As remover.

• Journal of Environmental Impact Assessment
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• v.32 no.3
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• pp.166-175
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• 2023

This study aims to identify the cause of the red-water occurrence (the phenomenon of water being red) that occurs at some points and sections of rivers in Yongin City. As a result of conducting a preliminary investigation, total three sites were selected as the investigation point as it was found that the red-water occurrence continued. As a result of the investigation, it is judged that the cause of the red-water in Yongin-city river is due to the soil color and iron content of the region. JPS, SBS, and JJS sites all showed that the color of soil is mainly consist of reddish brown and red-yellow. The average Fe concentration was 13.75 mg/L, 10.85 mg/L, and 1.31 mg/L, for each sites, and considering that the Fe concentration in general river water was less than 0.5 mg/L, it was confirmed that the concentration was quite high. At the JPS and JJS points, the red-water occurrence occurred mainly in stagnant places, which is believed to be strengthened by the reaction of organic and microorganisms. In the case of SBS, the wateris red, but as a result of observing the actual color, it is judged that the iron component deposited in the pipe causes an optical illusion with a deep red color. In addition, it is believed that the iron concentration can be reduced to the general river water concentration range by removing the particulate iron component through a decrease of more than 95% as a result of filtering with glass fiber filter with particulate iron. As a result of this study, it is necessary to manage the river to maintain the flow, and it is believed that the occurrence of red-water at the survey point can be alleviated through uptake action through planting and agglomeration precipitation and agglomeration filtration methods for particulate iron treatment.