• Geotechnical Engineering
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• v.12 no.3
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• pp.99-108
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• 1996

The physical and chemical properties of polyurethane-yieding twofomponent liquid injection mixture and those of the resulting polyurethane solid foam for chemical grouting are investigated. The chemical experiments on the factors influencing the properties of polyurethane show that the behaviors of polyurethane-yielding liquid material and those of the produced polyurethane solid foam are greatly affected by the ground conditions such as temperature, water content and density of soil. The ground reinforcing and water -blocking effects of polyurethane grouting are examined through field case history of tunnel ericavati on of the subway under construction.

• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.217-231
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• 2022

Reinforced polyurethane foam (R-PUF), a material for liquefied natural gas cargo containment systems, is expected to have different mechanical properties depending on its stacking position of foaming as the glass fiber reinforcement of R-PUF sinks inside R-PUF under the influence of gravity. In addition, since R-PUF is not a homogeneous material, it is also expected that the coordinate direction within this material has a great correlation with the mechanical properties. So, this study was conducted to confirm this correlation with the one between the mechanical properties and the stacking position. In particular, in this study, R-PUF of 3 different densities (130, 170, and 210 kg/m³) was used, and tensile, compression, and shear tests of this material were performed under 5 temperatures. As a result of the tests, it was confirmed that the strength and modulus of elasticity of the material increased as the temperature decreased. Specifically, the strength and modulus of elasticity in the Z direction, which was the lamination direction, tended to be lower than those in the other directions. Finally, the strength and elastic modulus of different specimens of the material found at the bottom of their lamination compared to the specimens with these properties found at positions other than their lamination bottom were evaluated. Further analysis confirmed that as the temperature decreased, hardening of R-PUF occurred, indicating that the strength and modulus of elasticity increased. On the other hand, as the density of R-PUF increased, a sharp increase in strength and elastic modulus of R-PUF was observed.

• Fashion & Textile Research Journal
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• v.25 no.4
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• pp.497-507
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• 2023

This study measured the effect 3D printing products comprised of different materials and shapes on heat transfer in clothing to derive fundamental data on thermal comfort among clothing comfort. The variables were three types of material (EVA foam, TPU-10%, TPU-10%+EVA), two types of shape (without holes, with holes), and two types of covers(without cover, with cover). All samples (12 types) prepared by combining these variables were placed on the hot plate set at 36℃, and the surface temperature was measured at three points for 10 minutes. The surface temperature change was dependent on the material, shape, and cover of the sample. The sample printed with TPU exhibited higher temperature transfer compared to the EVA foam sample after 10 mins. In addition, the temperature transfer was better when there were holes, and rate decreased when the sample was covered with fabric. We confirmed that material selection of the pad and thermal conductivity of the cover are extremely important in solving thermal stress to the human body caused by functional clothing with protectors. Additionally, as the protector, it is recommended to design the outer shell with a passage, such as a hole, to allow the rapid transfer of heat to the external environment.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.205-211
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• 2014

The purpose of this document is to provide basic data helpful in selecting seating device material by examining the affects of polyurethane foam material on seating pressure. In order to achieve this study objective, four seats, 6cm in height, were produced in hardness of: 13, 28, 25, and $45kg/cm^2$. To measure the sitting pressure distribution (depending on the characteristics of the produced seats), 10 healthy subjects participated in the experiment. XSENSOR was used a measuring device, and each seat was mounted on a wheelchair simulation. By analyzing the obtained data with Average Pressure(AP), Peak Pressure(PP,), and Contact Area(CA), the sitting pressure was measured for five minutes on each seat. This experiment showed the following results: There were significant differences between the AP, PP, and CA in the seat material (p<0.5). While the hardness of $18kg/cm^2$ showed low pressure, the hardness of $45kg/cm^2$ showed high pressure. This study also showed that seat material made of polyurethane should be considered when selecting seats. If polyurethane foam is used in seat recommendations, it will be recommended to use $18kg/cm^2$ for the proper hardness of the seat material.

• 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.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.618-623
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• 2008

To enhancement heat transfer performance, the metallic foam as heat exchanger was studied rapidly. This was attributed to its high surface area to volume ratio as well as intensive flow mixing by tortuous flow passages. So the experimental study about the heat transfer characteristic of metallic foam is presented in this paper. The material in this experiment was used as FeCrAl which has density of 10 ppi, 20 ppi and 30 ppi respectively. And the results show the heat transfer is rise with permeability Reynolds number increase and the pressure drop metallic foam was increased with the ppi increase.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.281-286
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• 2007

A chemical and biological permeable barrier with economic feasibility is suggested to treat landfill leachate in this study. The proposed composite layers consist of bentonite, and polyurethane (PU) foam that is mixed with powdered activated carbon (PAC) and inoculated with microorganisms from local wastewater treatment plant. Each layer is mixed with local sand, and yellow brown soil. Batch tests were conducted to investigate the sorptions of nitrate on the PU foam and PAC, and nitrification/denitrification rate of each layer material. Nitrification occurred in 30 minutes with initial ammonia concentration of 100 mg/L, and the concentration of nitrate attached in the PU foam increased after 270 minutes. Results of denitrification batch tests showed 76.6%, 87.3% and 88% of nitrate removal efficiency at 10%, 20% and 30% of the volume ratio of PU foam, respectively. The pH increased from 7 to 9.42, and alkalinity increased from 980 mg/L to 1720 mg/L during the denitrification batch tests. In the column experiments using the proposed composite layers with 20% of the volume ratio of the PU foam, about 96% of BOD, 63% of COD, 58.1~79.5% of total nitrogen were removed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.304-310
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• 2018

The aim of the research is to provide possibility of quality controlling by rheological properties for lightweight foamed concrete. The lightweight foamed concrete achieves its low density by containing air bubbles (foam) produced during the mixing process. Therefore, containing foamed volume during setting period is critical for the securing the performance as an insulating material. In this research, regarding foam collapse during the setting period, rheolgocial properties of fresh state lightweight foamed concrete were assessed to get its relationship with volume stability, or foam stability. For the experiment regarding foaming factors including mixing time, mix design of contents for materials, rheological properties of fresh state lightweight foamed concrete were tested with its density and settling depth. Based on the settling depth with various factors, relationship with rheological properties was analyzed, and especially, close relationship of plastic viscosity and settling depth was found. Therefore, from the results of this research, it is considered to contribute on suggesting a new approach of quality controlling for lightweight foamed concrete using rheological test method.

• Journal of Adhesion and Interface
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• v.22 no.1
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• pp.22-28
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• 2021

Products using diatomaceous earth, which are used in various fields, are optimized for moisture absorption, but have problems such as high hardness, powder flying, and rough surface feel. To improve this, an olefin-based foam having low hardness and high elasticity was prepared by adding an excessive amount of inorganic material using EVA (Ethylene vinyl acetate) having low hardness and excellent elasticity. Diatomaceous earth was added to impart moisture absorption characteristics of the foam, and the moisture absorption/drying characteristics showed a moisture absorption rate of about 10 to 15% and a moisture drying rate of 10 to 70% depending on the content of the diatomaceous earth. Through this study, it was possible to manufacture a water-absorbing olefin-based foam with diatomaceous earth added, and it was confirmed that the diatomaceous earth added to the foam had a great influence on water absorption and dissipation due to its microstructure and characteristics.

• Advances in concrete construction
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• v.16 no.6
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• pp.291-302
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• 2023

As the first part of the body that strikes the ground during running, sports shoes are especially important for improving performance and reducing injuries. The use of new nanotechnology materials in the shoe's sole that can affect the movement angle of the foot and the ground reaction forces during running has not been reported yet. It is important to consider the material of the sole of the shoe since it determines the long-term performance of sports shoes, including their comfort while walking, running, and jumping. Running performance can be improved by polymer foam that provides good support with low energy dissipation (low energy dissipation). Running shoes have a midsole made of ethylene propylene copolymer (EPP) foam. The mechanical properties of EPP foam are, however, low. To improve the mechanical performance of EPP, conventional mineral fillers are commonly used, but these fillers sacrifice energy return. In this study, to improve the magnificence of physical education training with nanotechnology, carbon nanotubes (CNTs) derived from recycled plastics were prepared by catalytic chemical vapor deposition and used as nucleating and reinforcing agents. As a result of the results, the physical, mechanical, and dynamic response properties of EPP foam combined with CNT and zinc oxide nanoparticles were significantly improved. When CNT was added to the nanocomposites with a weight percentage of less than 0.5 wt%, the wear resistance, physical properties, dynamic stiffness, compressive strength, and rebound properties of EPP foams were significantly improved.