• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.99-105
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• 2000

Greases composed of base oil and thickener are widely used in the purpose of lubrication and anti-corrosion of machinery. However, greases are sometimes oxidized and decomposed by heat of friction, and produced organic acid. And the greases leaked out ordinary spot make the concrete structures weaken. In this study, the chemical effects of the greases with the concrete structures were investigated through oxidation reaction under pressure and oxygen, and evaluated by the analysis of TAN, Ca content, FT-IR and XRD of grease and cement powder after the oxidation reaction. As the results, TAN value decreased with the increase of the content of cement because of neutralization of organic acid produced by the oxidation of grease with calcium contained in the cement. The content of calcium linearly increased with the increase of cement due to calcium salt by neutralization of acid. Also, according to XRD results of the cement powder oxidized at 99 $^{\circ}C$, the diffraction peak due to calcium hydroxide decreased in comparison with that at room temperature because of the reaction of calcium and organic acid.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.1
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• pp.138-146
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• 2006

The characteristics of backwash and concentrate discharges depend upon the quality of the water being treated and the net recovery of the membrane system. This paper is to indicate a design methods on the capacities of residuals treatment facilities in membrane processes for drinking water. We operated a demonstration membrane plant with a recovery rate of 90% for designing G-water treatment plant. We investigated on design parameter (optimum coagulant dosage and surface loading rate etc.) to design efficiently the residuals treatment facilities. The settling test was conducted with 1m columns dosing PACl to kaolin and membrane residuals under the experimental condition that discharge permit was under a 60mg/L. When the quantity of membrane residuals was $1,575m^3/day$, the estimated results for 1st thickener demonstrated the surface loading rate of 14.4m/day, detention time of 5.83hr, available depth of 3.5m.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.1005-1010
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• 2001

Recently, polymer-modified mortar has been studied for proposed use on industrial floors as top layers with thin thicknesses, typically 5~ 15mm. The purpose of this study is to evaluate basic properties of self leveling materials using polymer modifier as kinds of SBR, PAE, SUBA. Superplasticizer and thickener have been included in the mixes to reduce bleeding and drying shrinkage as well as in order to facilitate the workability required. The self leveling materials using four types of polymer dispersion are prepared with polymer-cement ratios which respectively range from 50%, 75%, and were tested for basic characteristics such as adhesion in tension, crack resistance test, rebound test after the preparative tests for unit weight, air content, consistency ratio etc. The results show almost as equal quality as existing commercial industrial flooring when mortar is modified by polymer dispersion. Adhesion in tension of polymer modified mortars using each SBR and PAE emulsion was over 10 kgf/$cm^{2}$. Crack or flaw derived from shrinkage is strongly dependent on the type of polymer dispersion because of each different total solid of polymer. It is judged that polymer modified mortar with self-leveling can be very well suited for Floor-finished.

• KCI Concrete Journal
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• v.13 no.2
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• pp.58-66
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• 2001

Recently, polymer-modified mortar has been studied for proposed use on industrial floors as top coat with thin thickness, typically 5~15mm. The purpose of this study is to evaluate basic properties of self-leveling materials using polymer dispersions as kinds of SBR, PAE, St/BA with thin coat (under 3mm). Superplasticizer and thickener have been included in the mixes to reduce bleeding and drying shrinkage as well as to facilitate the workability required. The self-leveling materials using four types of polymer dispersion are prepared with polymer-cement ratio which respectively range from 50% and 75%, and tested for basic characteristics such as unit weight, air content, flow, consistency change and adhesion in tension. From the test results, the self-leveling materials using PAE emulsion at curing age of 28days are almost equal to those of conventional floor using urethane and epoxy resin. The adhesion in tension of self-leveling mortars using SBR latex and PAE emulsion at curing age of 3days is over 17 kgf/cm$^2$(1.67MPa). Consistency change is strongly dependent on the type of polymer dispersion. It is concluded that the self-leveling materials using polymer dispersions can be used in the same manner as conventional floor using thermosetting resin in practical applications, in the selection of polymer dispersions.

• Tribology and Lubricants
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• v.22 no.5
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• pp.269-275
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• 2006

Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve bearing lubrication. Three urea/ether oil greases with different composition were synthesized to compare the performance of these greases. The typical grease physical properties were investigated, and life test of these greases was conducted by FE-9 grease life tester. The grease with higher content of the thickener showed higher performance. After these preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT value. And optimized conditions for grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT value respectively. The optimized grease using OIT value showed longer grease life than that using dropping point. Two greases were synthesized following the optimum synthesis conditions by means of OIT value. Then grease life and other properties of these greases were investigated. These two greasaes showed longer grease life than typical urea/ether oil grease.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.109-114
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• 2012

In this study, both sedimentation and thickening experiments were conducted for residuals produced from an advanced water treatment plant for more accurate and practical design of residual treatment train. In order to design a backwashed residual sedimentation basin (SRSB) in the filter backwash water recycle system, two kinds of backwash waters, one from sand filter (SFBW) and the other from GAC adsorption bed (GACBW), were separately collected and their surface loading rate measured. In addition, in order to design a gravity thickener, batch thickening tests were conducted for concentrated residuals taken from sedimentation basin and their limiting solid flux ($SF_{L}$) measured. From the experimental results and consideration of the seasonal characteristics of the residual, surface loading rate of $70m^{3}/m^{2}{\cdot}d$ was proposed as a design parameter for SRSB and solid loading rate of 20 kg $TS/m^{2}{\cdot}d$ was proposed as a design parameter for gravity thickeners. Finally, the material mass-balance was made for the design of each unit process in the residual treatment train.

• Solar Energy
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• v.17 no.2
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• pp.67-74
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• 1997

Spherical shape of phase change material(PCM) has been prepared by using sodium acetate trihydrate as a latent heat storage medium. Gelatin was used as an effective thickener to prevent undesirable phase separation. Sodium pyrophosphate decahydrate was used as nucleator to decrease the degree of supercooling in the thickened phase change material. Spherical PCM particles of 3-3.5 mm in diameter continuously manufactured with molten PCM with those conditions. The particle size of PCM was not affected by the effluent velocity of molten PCM in range of 1.3-1.8 ml/min. DSC, SEM and XRD were also used to characterize the properties of PCM particles.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.44-52
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• 1994

The purpose of this experimental research was focused to improve the quality of the effluent and the yielded sludge when the papermill wastewater was treated by the indirect aerated submerged biofilter as a second treatment method of papermill wastewater. Changing the various experimental factors(Nutrient additions or not, HRT, F/M ratio, recirculation ratio, etc) with indirect aerated biofilter, the results obtained are as follows. 1. Because of the microbes concentration could be sustained to $9,000mg/l$ in submerged biofilter and then the volumetric organic loads could be increased to $2.7kg-BOD/m^3/day$(that of activated sludge is $0.8kg-BOD/m^3/day$), the reactor volume can be reduced to one third of the activated sludge treatment. 2. Because of the yield coefficient(Y) and the endogenous decay coefficient(kd) were revealed 0.4 and 0.07/d, the yielded sludge volume was reduced by for compared with that of the activated sludgg process. 3. The concentration of the sloughed sludge in the reactor was 2.62~4.01%, so the thickener could be omitted in the papermill wastewater sludge treatment process. 4. When the operating was conducted at HRT of 4hrs, the treatment efficiencies of BOD and COD were obtained 80% and 70%, Therefore operating time can be reduced to one half of the activated sludge treatment.

• Journal of Environmental Science International
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• v.13 no.6
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• pp.571-579
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• 2004

There is a need to improve the efficiency of the existing sanitary treatment facilities, because the effluent standard becomes more stricter and septic sludge increased. Thus, operating processes of sanitary treatment system in M city changed with installation of additional facilities. Process modifications were as follows: Dilution water was added to the next process after primary aeration tank. Some secondary sedimentation sludge was recycled to primary aerator so that most of the organics were stabilized in primary aeration tank under automatic control of dissolved oxygen. The line of effluent from dewatering process flowing to the activated sludge tank was changed to the primary aerator. The primary sedimentation sludge line was linked to a thickener. Polymer was added to the activated sludge tank. The effluent of primary aerator and aerobic digester was recycled from the 5th to the 1st sector. As consequencies of above process modifications, the improvement of removal efficiency was achieved as BOD 54%, COD 42%, SS 61%, T-N 39%, and T-P 12%, respectively.

• Korean journal of food and cookery science
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• v.31 no.2
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• pp.200-206
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• 2015

The use of gums in processed foods manufactured in Korea was investigated in this study. The information about gums added to each food was collected from the ingredient claimed on the food packaging. A total of 272 food items were found to use gums as a thickener, stabilizer, and/or emulsifier. Among them, carrageenan was the most frequently found in 110 items (40%), followed by xanthan gum in 87 items (32%), guar gum in 67 items (25%), arabic gum in 50 items (18%), and gellan gum in 28 items (10%). Application of more than two different gums to food items was also observed, presumably based on the synergistic interaction between gums for a specific physical property. Of nine food categories classified by the Korea Food Code, gums were used most frequently in beverages, noodles, and meat products. Foods for children which include confectioneries, beverages, and chocolates were found to frequently use arabic gum, carrageenan, xanthan gum, guar gum, or gellan gum. These results indicate that gums have been widely using in a variety of Korean processed foods in order to improve their physical properties. Considering potential health concern of some gums such as carrageenan, further study to estimate daily intake of gum is needed.