• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.61-62
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• 2008

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.756-759
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• 2003

It is increasing the interest on the comfortable dwelling environment and the efforts to solve the problem of the floor impact noise in apartment houses have been realized, as a result numerous products have been made. The purpose of this study is to investigate the sound insulation performances according to foaming rate of floor impact noise insulators and flooring coverings in Mock-up Test Room. The test results of impact insulation performance for each floor impact noise insulators is that double structure of insulator is excel than one in low-middle frequency band and as foaming rate go up, the sound insulation performance is improved.

• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.43-49
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• 1998

The availability of large quantities of waste woods provides an impetus for investigating woody biomass potential uses. Polyurethane (PU) foams are prepared with reacting isocyanates and polyols, and are used. in various industry fields. Thus, lignocellulosic waste raw-materials are proposed as replacement for synthetic polyol to PU foam formulation. In this study PU foams were manufactured from liquefied woods, methanediisocyanate(MDI), catalyst, foaming stabilizer, and viscosity aids. The polyol content, isocyanate.hydroxyl group (NCO/OH) ratio, and water content were varied to evaluate their effects on the foaming and water absorption of the PU foams. Less than 400 Molecular weight. of polyethylene glycol(PEG) and 1 to 3 solvent to woody raw-material ratio were desirable for liquefying woody materials. Liquefying rate was increased with more than 3 % addition of inorganic and organic catalysts and raising reaction temperature more than $150^{\circ}C$. Addition of starch enhanced liquefying of woody materials. Fourty percents of starch resulted in about 90% liquefying rates. Foaming rates were increased with increasing moisture contents of liquefied wood. Moisture contents of 0.6% resulted in 5 time-foaming rates, and seven percents of moisture contents more than 30 time-foaming rates. But, an increase in water content may result in a decrease in cross-links between wood polyol and isocyanate, because the NCO/OH ratio is constant. Increasing moisture contents have significantly decreased density of PU foams. The optimum water content should be about 2.5% or less in this adopted condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.351-352
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• 2007

• Elastomers and Composites
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• v.36 no.1
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• pp.52-60
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• 2001

Physical properties of foams depend on the density of foams, Physical properties of base polymers, open ceil contents, and cell structures including the size, size distribution, shape of ceil and the thickness of membrane and strut. The density of foam is affected by raw materials, concentration oi crosslinking agent and blowing agent and process parameters such as processing technique and condition. Ethylene vinyl acetate copolymer(EVA) foam is a crosslinked cellular material. The foaming characteristics and physical properties of EVA foam are affected by decomposition rate of blowing agent. In this study, the decomposition rate of blowing agent and crosslinking rate, foaming characteristics and physical properties of foams were evaluated. The slow decomposition rate of blowing agent results in low density foam, good shock absorption property and uniform cell size distribution compared to the high decomposition rate of blowing agent.

• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.55-62
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• 2010

The performance evaluation of a sodium lauryl sulfate to qualify as a foaming agent is presented in this paper. When new surfactants are used a systematic study of production parameters on the foam characteristics needs to be undertaken unlike proprietary foaming agents and foam generator for which manufacturer has predefined the parameters. The relative influence of the foam parameters and optimization of factors were carried out through a systematic experiment design. The foam production parameters namely foam generation pressure and dilution ratio of foaming agents are observed to have significant effect on all foam characteristics with the exception of foam output rate on which only foam generation pressure has influence. The foam with good initial foam density need not necessarily be stable foam. The optimum levels of foam production parameters are determined for the surfactant Sodium lauryl sulfate which can be used to produce stable foam for foam concrete production.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.695-698
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• 2002

Induction heating process is one of the most efficient heating process in terms of temperature control accuracy and heating time saving. In the past study, fabrication process of cellular 6061 alloys by powder metallurgical route and induction heating process was studied. To supplement the framing conditions that studied in past study, effect of induction heating capacity and holding time at foaming temperature were investigated. Under the achieved framing conditions, teamed 6061 alloys were fabricated for variation of foaming temperature, and porosities(%)-foaming temperature curves were obtained by try-error experimental method. Uniaxial compression tests were performed to investigate the relationship between porosities(%) and stress-strain curves of framed 6061 alloy. Also, energy absorption capacity and efficiency were calculated from stress-strain curves to investigated. Moreover, dependence of plateau stress on strain rate was investigated in case of cellular 6061 alloy with low porosities(%)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1414-1417
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• 2003

In chemical forming process, mixed materials of LDPE, EVA and forming agent are used. However mechanical properties has been dropping remarkably through this forming process. In this study, Above materials(LDPE, EVA) were used in microcellular foaming injection process. And various effective factors in this process were selected by Axiomatic approach and systematically estimated by DOE(Design of Experiments). As a results, injection type and rate of mixing resins have more influence on forming rate than other factors.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.310-323
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• 1983

To study the effect of foaming agent on the production and property of light weight concrete, the tests of compressive, tensile, bending strengths and absorption rates of mortar were done under the different mixing ratio with J, A and D foaming agents. The results obtained were summarized as follows : 1. The strengths were decreased in richer mixing ratio and more addition of foaming agent. The decrease of strengths was the greatest at the level of 0.75% of foaming agent. The decreasing rate of strengths was in order of J, A and D foaming agent. 2. At the mixing ratio of 1:1, ${\sigma}_{28}$ and 0.75% of foaming agent, the compressive strength was decreased up to 34.9% by D, 47.8% by A and 86.8% by J foaming agent, respectively, the tensile strength was decreased up to 14.8% by D, 20.2% by A and 77.9% by J foaming agent, respectively, bending strength was decreased up to 19.9% by D, 35.0% by A and 79.1% by J foaming agent, respectively. The decrease of compressive strength was more severe than that of tensile and bending strengths. 3. The absorption rates were increased in poorer mixing ratio and more addition of foaming agent. The absorption rate was significantly higher at the early stage of immersed water. The absorption rate was in order of J, A and D foaming agent. 4. The decrease of strengths was inevitable in cement-mortar with foaming agent, but the cement mortar with foaming agent has such the properties of the light-weight, lnsulation, Keeping-warmth, sound proof and fire-proof that if could be utilized to the constructions which need low strengths.

• Elastomers and Composites
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• v.41 no.3
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• pp.147-156
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• 2006

To investigate the influence of the foaming temperature and carbon black content on the cure behaviors and foaming characteristics of the foams. natural rubber (NR) was foamed at five temperature zones (145, 150, 155, 160 and $165^{\circ}C$) and different feeding ratios of the carbon black. A decreasing trend of the scorch time, $t_{s2}$ and cure time, $t_{90}$ was observed upon increasing foaming temperature and carbon black content. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be $165^{\circ}C$ where density of the loomed NRs is lower than those at other four temperature regions. The rule rate index of the NRs foamed at $145^{\circ}C$ is smaller than those at 150, 155, 160 and $165^{\circ}C$. The results of the expansion ratio and micrographs of the foamed NRs were founded to support the density characteristics. The thickness of each of the struts formed inside the rubber matrix decreases with increasing the foaming temperature, while it increases with increasing the carbon black content.