• Polymer(Korea)
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• v.30 no.4
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• pp.286-292
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• 2006

Super water-absorbent resins were prepared by inverse suspension copolymerization of sodium acrylate, acrylamide and 2-hydroxyethyl acrylate using N, N'-methylene-bis-acrylamide as cross-linker. For the suspension copolymerization, monohexadecyl phosphate was employed as the dispersing agent, cyclohexane as the dispersing medium and potassium persulfate as the initiator. The dependence of water-absorption capacity on the amount of crosslinking agent, oil/water ratio, degree of neutralization and the composition of the copolymer were systematically investigated. Furthermore, the swelling kinetics of the super water-absorbent copolymer was carried out. The absorption of the resins is more than 1800 g/g for deionized water and 100 g/g for 0.9% NaCl solution, respectively. The copolymers showed an increased salt resistance and enhanced water retention of soil.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.84-90
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• 2015

Seventeen ampicillin-sensitive coagulase-negative staphylococci (CNS) isolates identified in jeotgal were subjected to assessments for antibiotic susceptibility and safety hazards. Fifteen of the 17 CNS strains exhibited phenotypic resistances to at least one antibiotic, and their prevailing resistance was to penicillin G. The dfrA gene for trimethoprim and tetK for tetracycline were amplified by PCR from the two strains, respectively. α-Hemolytic activity was not detected from the 17 strains, while five strains presented δ-hemolytic activity. Among the five strains, two strains exhibited β-hemolytic activity. Biofilm was formed from twelve strains. All of the tested phenotypic characteristics were expressed in a strain-specific manner.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.97-100
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• 2005

Recently sewage facilities mainly consisted of concrete structures are being deteriorated seriously by biodeterioration originated from sulfur-oxidizing bacteria. In this study, to prevent biochemical corrosion of the sewer concrete, antibiotics which prevent the growth of sulfur-oxidizing bacteria were developed and antimicrobial performance of it was investigated. After that, to consider applicability of antibiotics to concrete, durability such as resistance to carbonation, salt damage and chemical attack of concrete covered with inorganic and complex antibiotics were investigated. As a result of this study, it was proved that the antimicrobial performance of antibiotics was available. Also resistance to carbonation, salt damage and chemical attack of concrete covered with inorganic antibiotics was little improved but, in case of complex antibiotics, was remarkably improved. Moisture content of concrete, as a application condition of antibiotics in whole case, have little effect on performance but covering times of antibiotics have effect on performance only in case of complex antibiotics.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.472-481
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• 2009

Cementation phenomenon has a huge influence on geotechnical stiffness and strength under low confining pressure. The goal of this study is to evaluate the characteristics of stiffness according to the depth. The piezo disk elements are installed at each layer of the cell for the detection of the compressional waves. The change of compressional wave velocity is classified by three stages. The compressional wave velocities are shown different according to the depth. The compressional wave velocity is especially influenced by cementation, effective stress, and coordinate number. Furthermore, the electrical conductivity and cone tip resistance are measured according to the depth. The electrical conductivity and the cone tip resistance show the similar trend with the compressional wave velocity. This study shows that the cementation by salt is affected by the depth on the granular materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.577-580
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• 2006

This paper presents the experimental results of frost durability characteristics including freezing-thawing and de-icing salt scaling of the concrete used for gutter of the road. Mixtures were proportioned with the three level of water-binder ratio (W/B), 0.58, 0.53, and 0.48, and two binder compositions corresponding to Type I cement without any supplementary cementitious materials (OPC) and Type I cement with 30% blast-furnace slag replacement (Slag30). Also, two different solutions of calcium chloride and water that contains 0 and 8g of anhydrous calcium chloride in each 100 mL of solution, respectively, were used to evaluate their effect on the frost durability resistance. Test results showed that the Slag30 mixture exhibited higher durability factor and lower mass loss values than those made with OPC. Among the mixture tested in this work, the mixtures (OPC and Slag30) made with a relatively higher W/B of 0.58 exhibited large amount of the de-icing salt scaling regardless of calcium chloride concentration. Finally, the use of slag can be used effectively in terms of economy and frost durability of the concrete designated for gutter.

• Textile Coloration and Finishing
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• v.31 no.3
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• pp.177-186
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• 2019

In this study, we investigated for synthetic hydrotalcite in chloroprene rubber foam. Experiments were carried out to find the optimum content ratio by controlling the contents of MgO and Hydrotalcite. Swelling test in toluene immersion was made to measure the crosslinking density of CR foams, and the cure properties were investigated with flat die rheometer and Mooney viscosity. The difference of hardness, tensile strength and elongation at break were observed after immersing in 7% NaCl or 21% NaCl solutions for a day and four days. In addition, the volume change and water content remaining in CR foam were measured after immersing NaCl solution. As content of MgO increased, the value of the cure torque tended to increase, but it was almost constant above 2phr of MgO. However, the Mooney viscosity decreased with increasing MgO content. The crosslinking density, determined by the swelling ratio, showed that the CR compound without MgO showed a higher degree of swelling. When the content of hydrotalcite/MgO was 3:2, it was the lowest volume change of CR form. Also, As the content of hydrotalcite decreased, the difference of mechanical properties before and after immersion NaCl solution increased.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.661-664
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• 2008

The structure which is located in special surroundings like ocean-environment is physically and chemically eroded by seawater or salt damage, and then concrete-structure becomes deteriorated by iron corrosion and swelling pressure which leads to remarkably decline durability due to cracks and exploitation. As a measure against salt damage, it is actively being examined to use the blended cement that controls salt damage and fix chloride in the process of hydration. In this study, therefore, to examine the property of marine concrete added admixture, marine concrete is manufactured by adding high-strength admixture(omega2000) by 0, 5, 10, and 15% to low heat-blended cement. Then it shows that the compressive strength of manufactured marine cement tends to increase and chloride penetration resistance improves.

• Korean Journal of Food Science and Technology
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• v.2 no.2
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• pp.26-29
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• 1970

Four strains of Sporobolomyces genera were isolated from soy sauce mashes at the fermentating and aging periods and identified. Their salt-resistance and color formation were examined in order to improve the color density and nutrition of red pepper paste preparations. The results obtained were as follows; a) The strain L1, L2, L3 and L4 isolated were identified as Sporobolomyces gracilis, Sporobolomyces roseus, Sporobolomyes gracilis and Sporobolomyces roseus respectively. b) The yeasts isolated were grown on the media containing $0{\sim}10$ percent of sodium chloride but their growth were almost restrained on the media containing $15{\sim}18$ per cent of sodium chloride. And the strain L2 and L3 were more salt-resistant as compared with L1 and L4. c) The strain L3 were the best among the 4 strains of yeasts comparison with their salt-resistance, color and flavour formation.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.373-378
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• 2003

As a part of assessment of the structural material for the molten salt handling system, corrosion behavior of austenitic alloys, Fe-base and Ni-base in the molten salt of $LiCl-Li_2O_2$ was investigated in the range of temperature; 650~$725^{\circ}C$, time; 24- 168h, $Li_2O$; 3wt%, mixed gas; Ar-10%$O_2$. In the molten salt of $LiCl-Li_2O_2$, Ni-base alloys showed higher corrosion resistance than Fe-base alloys. Fe-base alloy with low Fe and high Ni contents exhibited better corrosion resistance. The scales of $Cr_2O_3$, $FeCr_2O_4$ on Fe-base alloys were showed, and $Cr_2O_3$, $NiFe_2O_4$ on Ni-base alloys were also showed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.143-151
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• 2007

This study presents the experimental results of frost durability including resistance to freezing-thawing and surface scaling of concrete. Mixing design was proportioned with the various water-binder ratio between 0.37 and 0.47 and three different binder compositions corresponding to Type I cement without any supplementary cementitious materials(OPC), Type II cement with 50% blast-furnace slag replacement(BFS50), and ternary cement with Type III cement, 15% fly ash, and 35% slag replacement (BFS35%+FA15%). Test results showed that the mixing design with BFS50% and BFS35%+FA15% exhibited higher durability factor than that made with OPC only. Finally, the use of blend cement containing slag can be used effectively in terms of frost durability of the concrete exposed to severe condition under coastal environment like as flying salt, sea water spray, etc.