• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.5-8
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• 2005

Sound absorbing performance is affected by porosity and continuity of void, therefore it is important to maintain stabilization of foam and to analyze properties of void pore in hardened state. The purpose of this study is to analyze the sound absorption properties and void characteristic of foamed concrete according to dilution ratio of foaming agent. The results of this experiment were as follows. It is determined that an increase in total and continuous void ratio is achieved by increasing of dilution ratio, and a shorter absorbing time was exhibited at a higher continuous void ratio. When the average void size of foamed concrete was below 1.5mm, the tendency of sound absorption coefficient compared with general sound absorber was appeared similarly.

• Journal of the Korea Institute of Building Construction
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• v.9 no.4
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• pp.63-73
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• 2009

Recently, the use of lightweight panels in building structures has been increasing. Of the various lightweight panel types, styrofoam sandwich panels are inexpensive and are excellent in terms of their insulation capacity and their constructability. However, sandwich panels that include organic material are quite vulnerable to fire, and thus can numerous casualties in the event of a fire due to the lack of time to vacate and their emission of poisonous gas. On the other hand, lightweight foamed concrete is excellent, both in terms of its insulation ability and its fire resistance, due to its Inner pores. The properties of lightweight concrete is influenced by foaming agent type. Accordingly, this study investigates the insulation properties by foaming agent type, to evaluate the possibility of using light-weight foamed concrete instead of styrene foam. Our research found thatnon-heating zone temperature of lightweight foamed concrete using AP (Aluminum Powder) and FP (animal protein foaming agent) are lower than that of light-weight foamed concrete using AES (alkyl ether lactic acid ester). Lightweight foamed concrete using AES and FP satisfied fire performance requirements of two hours at a foam ratio 50, 100. Lightweight foamed concrete using AP satisfied fire performance requirements of two hours at AP ratio 0.1, 0.15. The insulation properties were better in closed pore foamed concrete by made AP, FP than with open pore foamed concrete made using AES.

• Fire Science and Engineering
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• v.28 no.4
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• pp.1-7
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• 2014

Several complex devices and equipments are installed in the car's engine room, including various kind of oils or other flammable materials. So re-ignition is very likely to take place in it. In addition, it is restrictive for the driver or the occupant to open the bonnet and to spray the fire extinguisher in the engine room due to the high possibility of explosion. Therefore, a fire extinguishing system, which can detect a fire and inject the fire extinguishing agent to extinguish it, and fire extinguishing agents including HFC-227ea, which can stand the high temperature within the engine room and hold the viscosity sufficient to keep it in the kind of foam, were developed and tested. And the suffocation effect and the cooling effect come from the fire extinguishing principle of the foam fire extinguishing agent and the inhibiter catalyst effect come from the one of HFC-227ea was led simultaneously, and fire extinguishing agents without the secondary damage caused by residuals after the fire extinguishment like a case of the powder fire extinguishing agent, were developed. And experiments using a vehicle collision after the discharge is complete, foreign material can be removed without extinguishing the advantage that experimental results obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2945-2950
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• 2015

While perfluoroalkane (PFA), a liquid state nucleating agent for a rigid polyurethane foam (RPUF) to enhance the thermal insulation property, has the excellent nucleating characteristics, it is very expensive as well as environmentally harmful due to the fluoride compound. Many researches, therefore, have been performed to develop the alternative nucleating agents to replace PFA. In the present work, a multi-wall carbon nanotube (MWCNT) was used as a sloid state nucleating agent, and thereby the effects on the property changes of the RPUF were carried out. Average cell size decreased from 165.6 for base RPUF to $162.9{\mu}m$ and cell uniformity was also enhanced, showing the standard cell-size deviation of 45.6 and 35.2, respectively. While k-factor of base PUF was $0.01763kcal/m.hr.^{\circ}C$, that of the sample with 0.01 phr MWCNT showed 1.02% reduced value of $0.01745kcal/m.hr.^{\circ}C$. Though the compressive yield stress is nearly the same as $0.030{\times}105Pa$ for the both samples, initial modulus of the sample with 0.01 phr MWCNT was higher than that of base sample. it was considered as the results that small amount of MWCNT could play a sufficient role as the effective nucleating agent for RPUF, showing that an echo-friendly RPUF with reduced-cost could be fabricated, which has an enhanced thermal and mechanical properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1775-1781
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• 2008

The effects of the type of curing agent on the swelling of the natural rubber(NR) sponge applicable to the self-sealing layer of a helicopter fuel tank were investigated. The curing systems employed were peroxide and mixed ones of sulfur and peroxide. The NR compounds were prepared in a kneader and a roll-mill. The compounds were partially cured in a press at high pressure and subsequently cured fully with expansion in another press at atmospheric pressure. The apparent density of the NR sponge was measured and the cell structure was observed with scanning electron microscopy. The swelling experiments were performed at room temperature using toluene, iso-octane, and an aircraft fuel as a solvent. More rapid volume swelling of the NR sponge cured by peroxide was achieved than cured by sulfur and peroxide with similar amount of curing agent added in rubber compounds. The apparent density and cell structure of the sponge were extremely sensitive to the amount of peroxide, which influences again the swelling behavior of the NR sponge. It is important to control properly two reactions of decomposition of foaming agent and crosslinking of NR in the mold to obtain rapid swelling of the NR sponge on contact of the fuel.

• Food Science and Biotechnology
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• v.18 no.4
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• pp.900-903
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• 2009

An oat gum was extracted from whole seeds of a drought harvested oat (Avena sativa). Oat gum presented a ${\beta}-glucan$ content of 65%(w/w) and an intrinsic viscosity of 141 mL/g. Gelling capability of oat gum at different concentrations was investigated. Gel hardness increased from 0.08 to 0.25 N as the oat gum concentration changed from 5 to 10%(w/v). Whippability, foam stability, emulsion stability, and reduced viscosity of oat gum at different pH were also investigated. Oat gum whippability was maximum at pH 7 (146%), while the higher foam and emulsion stability values were found at pH 9 (88 and 96%, respectively). The gum reduced viscosity increased from 715 to 958 mL/g as the pH changed from 7 to 9. Oat gum shows great potential as a gel forming, thickening, and stabilizing agent.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.358-364
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• 1993

Low foaming scouring agents(SLFS) were prepared by blending of 2-ethylhexylaminoethyl sulfate, Na-dioctyl sulfosuccinate, Newpol PP-2000, MJU-100, ethylene glycol and organic solvent. As the results of several tests, SLFS-2 showed good scouring effect, penetrating ability, emulsifiability and anti-alkaline property, and showed not much water pollution. The foaming power of SLFS-2 measured by Ross & Mites method was 8mm foam height immediately after foaming. And the foaming power of SLFS-2 measured by Ross & Clark method were less than 300mm foam height at $30^{\circ}C$, and 15mm at $80^{\circ}C$. As a result, SLFS-2 was proved as a good low foaming scouring agent.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.2
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• pp.42-52
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• 2015

In this study, cellulose nanofibrils (CNF) were modified through carboxymethylation or TEMPO-mediated oxidation and their effects on ionicity and characteristics of sheet, film, and foam were investigated. Carboxymethylation was carried out on pulp fibers as a pre-treatment before preparation of CNF. The gel-like and translucent CNF hydrogel was obtained by grinding of carboxymethylated cellulose fibers. Carboxymethylated CNF film and freeze dried sheet showed higher transparency than that of untreated CNF. The CNF sheet with high strength and the CNF foam without large ice crystals were obtained by using the carboxymethylated CNF. TEMPO-mediated oxidation was carried out as a post-treatment of CNF. The zeta potential and charge demand of TEMPO-oxidized CNF were increased with an increase in oxidation time and addition amount of NaClO. The density of sheet made of TEMPO oxidized CNF was increased with the amount of oxidizing agent. The TEMPO oxidized cellulose nanofiber (TOCN) which was obtained from supernatant after centrifugation could be converted to transparent film.

• Polymer(Korea)
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• v.25 no.4
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• pp.528-535
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• 2001

Polyurethane specimens were mainly composed of polyol, MDI, silicone surfactant, and water. The effects of ethylene glycol on the cell size, forming magnification, cream time, gel time, take free time, final free rising height, and reactive temperature were investigated. The cyclopentane was used for PU foam as a physical blowing agent. The components were hand-mixed at about 5000 rpm within 4 seconds at room temperature. The mixtures with various ethylene glycol contents were foamed in the wood mold. When the index of isocyanate was fixed, as the amount of ethylene glycol increased, cell size and thermal conductivity were decreased by about 5.1% and 14%, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.34-35
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• 2019

In recent years, the construction industry has also applied the dry method that can be assembled in the field by industrialization and factory production, which is free from climatic effects and can reduce the cost due to mass production and simplify the work in the field. Among the building materials used in this dry method, ALC products are made by mixing calcium oxide, gypsum, cement, and water in silica and putting them in an autoclave to create voids in the interior through steam curing at high temperature and pressure. But it requires curing cycle conditions of warming, isothermal, and temperature curing. It depends on the performance of the product depending on the curing conditions, the economical efficiency due to high oil prices, the emission of greenhouse gases by the use of fossil fuels. Experiments were conducted to select an appropriate animal protein foam for lightweight foamed concrete block which was cured by applying a prefilling method to replace existing ALC products. As a result of investigating the characteristics of lightweight foamed concrete by type of animal protein foam, it is considered that FP3 is most suitable for manufacturing lightweight foamed concrete block.