• Journal of Soil and Groundwater Environment
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• v.7 no.2
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• pp.63-71
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• 2002

The authors selected the modified soil method, and then performed the geotechnical and environmental laboratory test, and evaluated whether the modified soil liner could be accepted as a barrier layer in landfill. Unlike the results of the natural soil(CL), those of the hydraulic conductivity test of stabilized soil met the standard value. According to these results, the optimal mixing ratio of a mixture(cement : bentonite : stabilizing agent) was 90 : 60 : 1 with mass ratio(kg) for 1㎥ with soil, and it was possible to use poor quality bentonite. B\circled2 because of a little difference from results with high quality bentonite. B\circled1. The Cation Exchange Capacity(CEC) of the modified soil was increased about 1.5 times compared with the natural soil; however. the change of CEC with a sort of additives was not detected. In order to observe the change of the chemical components and crystal structures, the natural and the modified soils with the sorts of additives were measured by the XRF(X-Ray Flourescence Spectrometer) and SEM, but there was no significant change. The artificial leachate with the heavy meals ($Pb^{2+}$ , $Cu^{2+}$, $Cd^{2+}$ Zn$^{2+}$ 100mg/L) was passed through the natural soil and modified soils in columns. In the natural soil, Cd$^{2+}$ and $Zn^{2+}$ were identified, simultaneously the pH of outflow was lower, and then came to the breakthrough point. The removal efficiency of the natural soil was showed in order of following : $Pb^{2+}$ ≒$Cu^{2+}$ > $Zn^{2+}$ > $Cd^{2+}$ On the other hand, modified soils were not showed the breakthrough condition like the result of the natural soil. The modified soil with the lower quality bentonite, B\circled2(column3) was more stable with respect to chemical attack than that with the higher bentonite, B\circled1(column2) because the change range of outflow pH in columns was less than that of outflow pH in column2. In addition, the case of adding the stabilizing agent(column4) was markedly showed the phenomena.ena.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.107-116
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• 2017

When drilling operation is being performed, many physical and chemical changes are occurred near wellbore. To handle various changes of well condition and keep drilling process safe, additives of bulk, such as bentonite for increasing density of drilling mud, barite for increasing viscosity of drilling mud, polymer for chemical control, or surfactant, are added into drilling mud through a mud shear mixer. Because the achievement of the required material property through mud mixing system is essential to stabilize drilling system, it is of importance to analyze multi-phase flow during mud mixing process, which is directly related to increase mixing performance of the system and guarantee the safety of the whole drilling system. In this study, a series of liquid-solid flow simulation based on a computational fluid dynamics (CFD) are performed with comparing to solid concentration in experiment by Gilles et al. [2004] to understand the characteristics of liquid-solid mixing in a mud shear mixer. And then, the simulation-based design of shear mixer are carried out to improve mixing performance in a mud handling system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.888-894
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• 2015

Inorganic composite particles have excellent physical and chemical characteristics and have been applied in various industries. Recently, many studies have examined the optical properties, such as light scattering, refraction, transmission characteristics, by coating organic-inorganic materials on a substrate, such as mica. Mica is widely applied as a pigment, plastics, painted products, and ceramics because of its high chemical stability, durability and non-toxicity. Magnesium oxide has a range of properties, such as high light transmittance, corrosion resistance and non-toxicity, and it is used as an optical material and polymer additives. To use the optical properties of mica and magnesium oxide, mica was coated with magnesium hydroxide by a dissolution and recrystallization process. In this study, the optimal conditions for the haze value of the particles were found by adjusting the amount of precursors and pH. Magnesium hydroxide layers were formed on the surfaces of mica and converted to MgO after calcination at $400^{\circ}C$ for 4 h. The results showed that the value of MgO-coated mica haze can be controlled easily by the amount of the magnesium hydroxide and pH. The optical properties of the inorganic composite powder were analyzed using a hazemeter and the highest haze value was 85.92 % at pH 9. The physicochemical properties of the synthesized composite was analyzed by SEM, XRD, EDS, and PSA.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1143-1152
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• 2019

In order to study the solubilization of aniline by cationic surfactants (DTAB, TTAB and CTAB), the solubilization constant (K_s) and thermodynamic functions were measured and calculated by using the UV-Vis method. The solubilization constants of aniline with the change of temperature were measured, and the effects of addition of ionic salts and organics on the solubilization constants were investigated. These effects of additives and temperature changes were compared and analyzed for each type of surfactant, and the solubilization of aniline was analyzed microscopically by comparing and evaluating the thermodynamic functions obtained from the solubilization constants. As a result, the Gibbs free energy and enthalpy changes were both negative and the entropy changes were positive within the measured range for the solubilization of aniline by cationic surfactants. The solubilization constant value decreased with increasing temperature and increased with increasing carbon chain length of the surfactant. As the concentration of ionic salts increased, the Gibbs free energy change increased at first and then decreased. In n-butanol solution, the Gibbs free energy change tended to increase continuously with increasing the concentration of n-butanol.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.3
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• pp.110-116
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• 2016

Biogas yields point of view, the possibility of reusing excess sludge treated by thermal pretreatment for the purpose of improving the efficiency of the anaerobic digestion process has been investigated in recent year. Thermal pretreatment technology was considered as a pretreatment technique to improve excess sludge properties because of the solubilization of particulate organics. As a view point of sludge reduction and recycle, however, many researchers focused on the ability of particulate hydrolysis and COD solubilization under a high temperature, and few reports have addressed on the physical/chemical characteristics changing. This research was performed to evaluate the effects of a various temperature and chemical additives on carbon formation and fractionation in treated slurry from thermal pretreatment. Based on the results, it was revealed that oxidants injection and temperature changing have significantly caused the change of carbon fractions in slurry from thermal pretreament. Especially, it was considered that the efficiencies of particle hydrolysis increased with the increase of the reaction temperature. Low molecular weight(Mw < 350 g/mol) organic carbon formation increased with the increase of oxidants injection. It was expected that results of this research will provide an overview of the characteristics of thermal pretreatement for excess sludge reduction and recycle.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.425-429
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• 1997

Polyisobutenylsuccinic anhydride(PIBSA), an intermediate for the lubricating oil additive, was prepared by the reaction of polyisobutylene(PIB) with maleic anhydride (MA). The functionality, which indicates the extent of reaction of PIB-a and MA, was determined in the various reaction conditions : fuctionality was 0.98 under the reaction conditions of no solvent for 12 hours at $190^{\circ}C$, 0.21 in benzyl alcohol solvent for 12 hours at $190^{\circ}C$, and 0.03~0.20 with various Lewis acids such as $AlCl_3$, $SnCl_4$, $Et_2AlCl$, and $TiCl_4$. The fuctionality also depended on the structure of PIBs. As ${\alpha}$-olefin content (exo-form) in PIB increased, the fuctionality had a higher value. The structure of PIBSA prepared from PIB and MA was determined with FT IR and $^1H$ NMR spectroscopy. Two strong anhydride IR bands at 1782 and $1855cm^{-1}$ were obserbed and two IR bands at 1639 and $897cm^{-1}$ for unsaturated groups of PIB disappeared. The presence of the anhydride was difficult to find by $^1H$ NMR spectroscopy because the anhydride protons gave relatively small peaks over a 2.0~3.0 range. Polyisobutenylsccinimide (PIBSI), a lublicating oil additive, was prepared by the reaction of PIBSA with diaminoethane.

• KSBB Journal
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• v.22 no.5
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• pp.271-277
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• 2007

Natural pigments have many applications like colouring agent, pigments, food additives, and antiseptics. At present, instead of synthetic pigments that have contributed to the development of industry, many kinds of natural pigments have been developed. The constituents of gardenia fruits, Gardenia jasminoides ELLIS, are traditionally known as herb medicine and natural dyes/pigments due to the customer is needs. The fruits produce yellow carotenoid pigments and iridoid compounds. The two main components in the yellow pigments are called crocin and crocetin. The extraction mode of yellow pigment from Gardenia is depended upon the extraction time, temperature, and volume of solvent. Red pigments or blue pigments formed from geniposide and amino acids have been reported a lot. Geniposide, the principal iridoid glucoside contained in gardenia fruit, was hydrolyzed to genipinic acid or genipin as a precursor for the pigment by enzymatic or chemical reaction. These red or blue pigments prepared with materials hydrolyzed of geniposide and amino acid and had properties governed by the electrostatic character of the amino acid. The pigments showed good stability to heat and pH but were gradually bleached by light while the other natural pigments are unstable in light, heat, acid, and base solution. The safety of the pigments was considered to be of little virulences in comparison to synthetic pigments.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.358-362
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• 2017

In this study, the optimization of extraction parameters (solvent, temperature, time, solvent concentration) for the maximization of polyphenol extraction was performed to produce value-added food and cosmetic additives using a byproduct of coffee extraction process (coffee residue). All of the extraction parameters evaluated in this experiment had significant effects on polyphenol extraction and the results showed the effect of NaOH concentration on the polyphenol production was most significant among tested parameters. Especially, hot water extraction using acid or base was effective rather than hot-water extraction and the addition of 0.1 mol of NaOH increased 1.5 times extraction concentration compared with hot-water extraction using distilled water. It was found that hot-water extraction with NaOH was more effective than hot-water extraction, and 36.5 mg GAE/g DM was obtained under optimum condition of $100^{\circ}C$, 2 mol of NaOH and 30 min. This result was 2.9 times higher than that of 12.5 mg GAE/g DM obtained from the hot-water extraction before optimization. Thus, coffee residue could be used for food and cosmetic industry as a high-value additive such as antioxidant.

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.449-470
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• 2018

A review of research trends on wood surface protection for exterior use obtained the following conclusions: It has been reported that inorganic compounds such as chrome and copper used as wood preservatives can protect wood from weathering. It has been shown that precoating with hydrophobic substances such as wax and oil, UV absorbers, and HALS (Hindered Amine Light Stabilizers) enhances weathering resistance on the surface of ACQ-treated wood. Opaque coatings of paint/stains and semitransparent stains on the surface of preservative treated wood can increase the synergistic effects on prevention of weathering deterioration. Also the need for repainting periodically for the protection of the preservative treated wood surface has also been suggested. ZnO or $TiO_2$ of fine particles, metal ions such as Co, Cr, Fe, Mn, Ni and Ti, and UV absorbers such as tris-resorcinol triazine derivatives, triazine and benzotriazole were introduced as additives for preventing UV in the transparent coating on wood. Several reports showed that chemical modification such as methylation, acetylation, or alkylations have made some increases the effects of preventing weathering with the increasing weight gain of chemical formulas. In heat-treated wood, there were various contradictory reports on the resistance of weathering, and there were some other reports emphasizing the necessity of painting with UV resistance, which leads to the necessity of more advanced studies.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.4
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• pp.401-413
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• 2013

Slurry shield tunnelling ensures stability by pressurizing the tunnel face with the slurry contained in the chamber. It resists water and earth pressure in order to prevent the failure in the tunnel face during tunnel excavation. If the ground is relatively coarse, slurry can not clog the tunnel face and excessive slurry infiltration will occur. In this case chemical compounds or additives should be added to the slurry in order to improve the clogging phenomena at the tunnel face. In this study, the effect of the carbon dioxide gas as an additive to the slurry instead of chemical compounds on the capability of enhancing the clogging in the tunnel face is investigated. Bubbles arising from the carbonate-added slurry are trapped in the soil voids enhancing the clogging capability. This effect is studied in this paper by performing laboratory model tests simulating in-situ conditions, and by adopting the fine particle clogging theory. Tunnel face stability analysis was also performed and it was found that the effective size ($D_{10}$) of soils which can guarantee tunnel stability utilizing the carbonate-added slurry increased from 1.0 mm up to 2.6 mm. Moreover, Stability analysis showed that the tunnel face is stable if the ${\lambda}$(deposition coefficient) value is greater than $0.007sec^{-1}$.