• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.388-393
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• 1999

Polyurethane foams are polymeric material with repeating groups of urethane and urea. When these are heated with ethylene glycol and K acetate catalyst at $200^{\circ}C$, the transesterification of them leads to soluble products. The mechanisms of the reaction were investigated from the molecular weight and the component distributions of the products by GPC and IR analysis. The degradation of the urethane groups was faster than that of urea groups in transesterification reaction. K acetate catalyst accelerated the rate of the transesterification because it had a high ionization tendency. Each reaction, using K or Sr acetate as a catalyst, progressed in the same reaction path but yielded different compositions in products because of the difference of the reaction rate.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.5
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• pp.448-455
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• 2018

Glass wool is an eco-friendly materials that is manufactured through a continuous process by processing waste glass. This materials is low cost compared with another materials and has excellent thermal conductivity. For this reason, glass wool is installed as insulation system for LNG carriers and as insulation of building wall as well as various industries. The mechanism of insulation of glass wool is the conduction of the wool itself and convection by space between fibers. Therefore, in order to develop the enhanced thermal conductivity of glass wool is necessary to reduce its own conduction or to insert additional material after manufacturing as well as prevent convection. In this respect, many researchers have been actively studying to decrease thermal conductivity of polyurethane foam using by inserted glass wool or change the chemical component of glass wool. However, many research are aiming reduction of glass wool itself. This study focus on post-processing and inserted different materials; silica-aerogel, kevlar fiber 1mm, 6mm and glass bubble. Experimental results show that the thermal conductivity almost decreases with the addiction of glass bubble and silica aerogel.

• Journal of Wetlands Research
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• v.8 no.2
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• pp.45-51
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• 2006

Biological enhanced treatment and send filtration are established being operated to remove nutrients and MBAS(Methylene Blue Activate Substance) in the most of Waste Water Treatment Plant(WWTP) in Korea. However, untreated synthetic detergents and nutrients which directly run into the water system present an unpleasant view because of the foam, taste and odor generating filamentous periphytic algae and interrupting self-purification in the stream. Therefore, this research was enforced to know the MBAS removal efficiency of the sand filtration about G WWTP which reuses effluent as urban stream management water. As a result, the maximum removal efficiency using sand filtration was 63% after 24 hours and particularly 30% after 2 or 4 hours which turned out to be not that effective. In conclusion, It is recognized that other methods of MBAS removal and a research will be needed which reuse effluent as urban stream management water from now on. Because the MBAS removal with sand filtration is insufficient with economical efficiency from the fact that it needs long hours for a sand filtration treatment and the removal efficiency was almost below the expectation.

• Resources Recycling
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• v.7 no.3
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• pp.3-10
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was treated by adsorbing colloidal flotation using Fe(III) or Al(IlI) as flocclant and a sodium lamyl sulfate as a collector. Parameters such as pH, surfactant concentration, Fe(III) or Al(III) concentration, gas flow rate, etc., W앙e considered. The flotation with Fe(III) showed 99.8% removal efficiency of cohalt on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, and flotation time 30 min. When the waste solution, was treated with 35% $H_2O_2$ prior to adsorbing colloidal flotation, the optimal pH for removing cobalt shifted m to weak alkaline range and flotation could be applied in wider range of pH as compared to non-use of $H_2O_2$. Additional use of 20 ppm Al(III) after precipitation of 50 ppm Co(II) with 50 ppm Fe(III) made the optimal pH range for preferable flotation w wider. Foreign ions such as, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $Ca^{2+}$ were adopted and their effects were observed. Of which sulfate ion was f found to be detrimental to removal of cob퍼t ion by flotation. Coprecipitation of Co ion with Fe(III) and Al(III) resulted in b better removal efficiency of cobalt IOn 피 the presence of sulfate ion.

• Korean Journal of Hazardous Materials
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• v.2 no.1
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• pp.18-26
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• 2014

We analyzed the demand of competent authorities requiring adequate technical information for initial investigation of chemical accidents. Reflecting technical reports on chemical accident response by environmental agencies in the U.S. and Canada, we presented information on environmental diffusion and toxic effects available for the first chemical accident response. Hydrogen fluoride may have the risk potential to corrode metals and cause serious burns and eye damages. In case of inhalation or intake, it could have severe health effects. The substance itself is inflammable, but once heated, it decomposes producing corrosive and toxic fume. In case of contact with water, it can produce toxic, corrosive, flammable or explosive gases and its solution, a strong acid, may react fiercely with a base. In case of hydrogen fluoride leak, the preventive measures are to decrease steam generation in exposed sites, prevent the transfer of vapor cloud and promptly respond using inflammable substances including calcium carbonate, sodium bicarbonate, ground limestone, dried soil, dry sand, vermiculite, fly ash and powder cement. The method for fire fighting is to suppress fire with manless hose stanchions or monitor nozzles by wearing the whole body protective clothing equipped with over-pressure self-contained breathing apparatus from distance. In case of transport accident accompanied with fire, evacuation distance is 1,600m radius. In cae of fire, fire suppression needs to be performed using dry chemicals, CO₂, water spray, water fog, and alcohol-resistance foam, etc. The major symptoms by exposure route are dyspnoea, bronchitis, chemical pneumonia and pulmonary edema for respiration, skin laceration, dermatitis, burn, frostbite and erythema for eyes, and nausea, diarrhea, stomachache, and tissue destruction for digestive organs. In atmosphere, its persistency is low, and its bioaccumulation in aquatic organism is also low.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.203-212
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• 2005

Cellulose insulation is primarily manufactured from recycled newsprint and treated with fire retardants for the fire resistance. Thanks to the fire retardants, it is not combustible and flammable. In addition to that, Its thermal resistance is much better than that of fiberglass or rock wool. It is made from waste paper and easily decayed when it is demolished, and it has small embodied energy. So it is very environment-friendly building material. For broader use of cellulose insulation in buildings in Korea, it is necessary to test its physical performance to compare the results with the requirements on the Korean Building Code. To this end, apparent thermal conductivity (ka) measurements of Korean-made loose-fill cellulose insulations were recently completed using equipment that was built and operated in accordance with ASTM C 518 and the fire resistance was tested in accordance with ASTM C 1485. Korean loose-fill cellulose has thermal conductivity about 5% greater than the corresponding U.S. product at the same density. This is likely due to differences in the recycled material being used. Both spray-applied and loose-fill cellulose insulation lose about 1.5% of their thermal resistivity for $5.5^{\circ}C$ increase in temperature. The fire resistance of cellulose insulation is increased in linear proportion to the increase of the rate of fire retardant. Thanks to the high fire resistance, cellulose insulation can be used as a substitution of Styrofoam or Urethane foam which is combustible. The thermal conductivity of cellulose insulation was $0.037-0.043W/m{\cdot}K$ at the mean specimen temperature from $4-43^{\circ}C$. It corresponds to the thermal resistance of "Na Grade" according to the Korean Building Code. The effect of chemical content on thermal conductivity was negligible for all but the chemical-free specimen which had the highest value for the thermal conductivity over the temperature range tested. The thermal resistance of cellulose insulation is better than that of fiberglass or rock wool, and its fire resistance is higher than that of Styrofoam or Urethane foam. Therefore it can be substituted for those above considering its physical performance. Cellulose insulation is no more expensive than Styrofoam or rock wool, so it is recommended to use it more widely in Korea.

• Korean Journal of Food Science and Technology
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• v.38 no.4
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• pp.488-494
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• 2006

This study was carried out in order to investigate the feasibility of utilizing concentrated sunmul (soybean curd whey), which is a waste by-product of soybean curd processing, as a functional food ingredient. Sunmul Powder was concentrated by ultrafiltration and spray dried with or without dextrin. Oil adsorption capacity of UF retentate powder was similar to that of ISP (Isolated Soy Protein) and higher than that of sunmul powder, whereas water holding capacity of UF retentate powder was lower than that of ISP. Protein solubility of all types of UF retentate powder was significantly higher than that of ISP at pH 2.0-10.0 with the lowest protein solubility seen at pH 4.0 and solubility increasing as the conditions became more acidic or alkaline. Emulsifying activity indexes of UF retentate powder at pH 2.0-10.0 were not influenced by pH. Emulsion stability of 4% sunmul solution was lowest at pH 4.0, but that of UF retentate powder was higher at acidic pH values and decreased with increasing pH. Foaming capacities of sunmul and UF retentate powder were high at pH 4.0-6.0, but the foam of UF retentate powder disappeared within 20 minutes in all conditions of pH.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.81-85
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• 2020

Shaving dust is a collagen fiber that is the leather waste occurred for thickness adjustment during the natural leather manufacturing process, and causes problems such as an environmental contamination because of a chromium (Cr) contained when it comes to reclaiming process. Various studies applying the shaving dust are currently being conducted in many countries across the world with an initiative by the EU. Of those applications, the bonded leather is being highlighted as a substitute for natural leather. Since the bonded leather, however, uses latex as a binder, accordingly it entails a high weight and a poor ventilation, which are deemed as disadvantages due to its dense internal tissues compared to other synthetic leathers. To address such disadvantages, this study employed the thermally expandable micro sphere to improve its air permeability and light weight by alleviating the internal structure. This is a study on the manufacturing of light bonded leather using the shaving dusts. In the study, the shaving dusts were forced to foam under 100~120℃ considering the heat resistance of collagen fiber after applying the thermally expandable micro sphere, and then the tendency was analyzed. In the analysis results, the most excellent foaming rate was exhibited when the shaving dusts were treated under 120℃ for 8 minutes and the variation of internal structure according to a foaming was observed through SEM analysis for the cross-section of the bonded leather.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.920-926
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• 1997

The catalytic glycolysis process is the method of chemical recycling where the polyol and carbamate compounds recovered by transesterification reaction are reused to produce new polyurethane foams. In this work, ethylene glycol, diethylene glycol, and 1,4-butanediol were used to decompose polyurethane foams and various metallic acetates were provided as catalysts. The catalytic glycolsis of polyurethane foams was taken place in the reaction temperature of $180{\sim}200^{\circ}C$. The reaction rates of catalytic glycolysis reaction were indicated by the viscosity of the reaction products at different reaction times. IR and GPC analysis showed the types and the molecular weight distributions of the products. The catalytic glycolysis was profitable for using ethyleneglycol at high temperature. The activities of the catalysts are suitable for K, Na, Tl acetate, and the products are composed of comparatively high-contained amine compounds and carbamate compounds. In the case of Sr acetate and Quinoline, the reaction rate was somewhat low. However, the content of polyol was high and the content of the side-products was low. The foams which were prepared by blending up to 20wt% of recovered polyol with virgin polyols showed better physical properties in tensile strength, hardness, tear strength, and compressive strength compared to those of polyurethane foams from virgin polyol.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.820-825
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• 2007

Earthworm casting was the natural fertilizer that contained high concentrations of nutrients such as nitrogen, phosphate and potassium and of over $10^8$ CFU/ml of microorganisms. Greater than 80% of feed was excreted through the fermentation by the intestinal enzyme, after worm had eaten feeds such as fallen leaves and rotten roots under the ground. Also, the soil structure of casting was known to be very efficient in the aspects of the porosity, the water permeability, and deodorizing activities. In this research, the biofilter packed with a biomedia made of casting and waste polyurethane foam, a binder, which helped to improve the durability and perpetuity of casting, was investigated to degrade malodorous hydrogen sulfide gas. The biomedia had no need of extra supply of nutrients and of microbial inoculations. On the beginning of the operations, it showed 100% removal of hydrogen sulfide gas without lag phase. At SV of 50 $h^{-1}$, hydrogen sulfide gas from the outlet of the biofilter was not detected, when inlet concentration increased to 450 ppmv. After that, removal efficiency decreased as increasing inlet hydrogen sulfide concentration. Hydrogen sulfide removal was maintained at almost 93% until inlet concentration was increased up to 950 ppmv, at which the elimination capacity of $H_2S$ was 61.2 g $S{\cdot}m^{-3}{\cdot}h^{-1}$. Maximum elimination capacity guaranteing 90% removal was 61.2, 65.9, 84.7, 89.4 g $S{\cdot}m^{-3}{\cdot}h^{-1}$ at SV ranging from 50 $h^{-1}$ to 300 $h^{-1}$, but was 59.3 g $S{\cdot}m^{-3}{\cdot}h^{-1}$ at SV of 400 $h^{-1}$. The results calculated from Michaelis-Menten equation revealed that $V_m$ increased from 66.04, 88.96, 117.35, 224.15, to 227.54 g $S{\cdot}m^{-3}{\cdot}h^{-1}$ with increasing space velocity in the range of 50 $h^{-1}$ to 400 $h^{-1}$. However, saturation constant$(K_s)$ decreased from 79.97 ppmv to 64.95 and 65.37 ppmv, and then increased to 127.72 and 157.43 ppmv.