• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1318-1323
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• 2013

Thermal insulation material was prepared by cross-linking chemical reaction of silica aerogel and epoxy resin, which has a high porous and vacant properties. The structural, mechanical, and thermal properties were analyzed in order to verify its application for industrial and electrical applications. The thermal conductivities were changed from 115 mW/mK to 75 mW/mK by reducing the contents of nano-porous silica areogel powders. The compressive loading is also decreased by increasing the contents of silica aerogels by 20 wt% in aerogel/epoxy composites. It is concluded that the formulated composite materials can be applied to building materials, electronics parts, and heavy industries.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.55-62
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• 2017

The grate bar, a component used in steel mills, is used in harsh environments where external disturbances such as high temperature, abrasion, corrosion, and impacts are present. Therefore, in this study, spray-coating was performed on the most severely affected surface to extend the lifetime of the grate bar. The thermal and mechanical properties of the sprayed coated bars were investigated based on the performances under abrasion, thermal shock, tension, and sand blasting, and the microstructures by microscope. By analyzing the thermal and mechanical properties of the uncoated original grate bar and coated grate bar and comparing them with one another, the physical performance improvement of the coated grate bar can be verified.

• Applied Microscopy
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• v.50
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• pp.12.1-12.11
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• 2020

Hot stage microscopy (HSM) is a thermal analysis technique that combines the best properties of thermal analysis and microscopy. HSM is rapidly gaining interest in pharmaceuticals as well as in other fields as a regular characterization technique. In pharmaceuticals HSM is used to support differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) observations and to detect small changes in the sample that may be missed by DSC and TGA during a thermal experiment. Study of various physical and chemical properties such sample morphology, crystalline nature, polymorphism, desolvation, miscibility, melting, solid state transitions and incompatibility between various pharmaceutical compounds can be carried out using HSM. HSM is also widely used to screen cocrystals, excipients and polymers for solid dispersions. With the advancements in research methodologies, it is now possible to use HSM in conjunction with other characterization techniques such as Fourier transform infrared spectroscopy (FTIR), DSC, Raman spectroscopy, scanning electron microscopy (SEM) which may have additional benefits over traditional characterization techniques for rapid and comprehensive solid state characterization.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.611-617
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• 1999

• Clean Technology
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• v.12 no.1
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• pp.11-18
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• 2006

In this study, aqueous polyurethane dispersion(PUD) was synthesized using polyhexamethylene carbonate glycol (PHMCG) as soft segment, isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA) as hard segment. Also, polyurethane/clay nanocomposites were prepared by adding pristine montmorillonite (PM) and organically modified clays, C15A and C30B into PUD. The degree of clay dispersion in the nanocomposites was investigated using XRD and the physical and thermal properties were examined through UTM and TGA. These results showed that nanocomposites with C15A gave higher physical and thermal properties than those with C30B or PM. As a result, the properties of nanocomposites were observed to vary depending on the types of clay modifiers and clay contents.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.5
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• pp.715-723
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• 2013

This develops a new and advanced S/S knitwear material made of linen/bamboo blended yarn. Linen/bamboo knitted fabrics were compared with linen/polyester knitted fabrics in terms of appearance as well as physical and comfort properties. Rib knitted fabrics were remarkably thicker than plain knitted fabrics. Knitted fabrics based on polyester yarns were heavier than those based on bamboo yarn. The porosity decreased in the following order: linen 100% > bamboo 100% > polyester 100%. The drape properties of bamboo 100% and linen/bamboo knitted fabrics were excellent. The pilling resistances of linen 100% and linen/bamboo knitted fabrics were excellent. The highest and lowest air permeability was observed in the case of linen/bamboo knitted fabrics and polyester 100% knitted fabrics, respectively. The instant cool-feeling was enhanced as the bamboo yarns were blended. The thermal conductivity of linen 100% knitted fabrics was the highest and the thermal conductivity of linen/bamboo knitted fabrics was higher than linen/polyester knitted fabrics. Bamboo 100% knitted fabrics showed a higher moisture regain than polyester 100% knitted fabrics. The results confirmed the superior appearance and comfort of a novel S/S knit wear material made of linen/bamboo knitted fabric.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.559-567
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• 1989

Bioglasses have been known to be as one of the promising biomateials, which can be used for replacing defective hard and soft tissue. There have been many reports on biological results for this type of glass, but no systematic work has carried out on the structures and properties of the bioglass itself. In the present study, the effect of P2O5 in bioglasses on their structures and properties was examined. Infrared and Raman spectroscopy for the glass structural analysis, differential thermal and X-ray diffraction analysis for the crystallization of the bioglass were performed, and several physical properties were measured. When the glasses were heat-treated, Na2O.2CaO.3SiO2 was the major crystalline phase and $\beta$-NaCaPO4 crystal was found for the glass with high P2O5 content. The added P2O5 in the glasses enhanced the polymerization of silicate glass structure and it changed the chain-like glass structure to a sheet-like structure, and some P2O5 may stay as phosphate monomer. With addition of P2O5 in the glass the density of the glasses decreased, but not much changes in their thermal expansion coefficient, softening point and microhardness were observed.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.979-990
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• 1990

The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their structures and physical properties are not fully understood. In the present work, several investigations such as Raman spectroscopic analysis, density, thermal expansion coefficient, softening temperature, and refractive index measurement were carried out to find the structures and physical properties of bioglasses, where MgO is substituted for CaO in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5 ; mole%). Hydroxyapatite formation on the glass surface reacted in Tris-buffer solution was also examined. When CaO was replaced by MgO, nonbridging oxygen in glass structuer was diminished but the degree of disorder increased. Thermal expansion and softening properties showed the mixed oxide effect. Hydroxyapatite were formed on the surface of 0~11mole% of MgO containing bioglasses, and the thickness of SiO2-rich layer as well as hydroxyapatite layer were unchanged with MgO content. However, the hydroxyapatite was not formed on the surface of the bioglasses containing over 11 mole percent MgO, even if the glasses were reacted for long period.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.1-4
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• 2005

This research is to present experimental materials model of high strength concrete for prediction of fire safety of structural members based on physical properties of materials during heating up to 800$^{circ}C$. The following conclusions are drawn from this study. First of all, between 100 to 200 $^{circ}C$, the physical models of concrete such as specific heat and thermal conductivity, show visible degradation, regardless of concrete strength. Second, between 300 to 600$^{circ}C$, the physical models of the 29MPa and 49MPa concrete show degradation continually at these temperatures. Finally, beyond 600$^{circ}C$, the physical models of 49MPa strength concrete show larger degradation than 29MPa strength concrete due to rise of pore pressure and melting of the interface between aggregate and cement paste.

• Journal of ILASS-Korea
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• v.27 no.2
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• pp.66-76
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• 2022

This study presents a prediction methodology of transport properties using the methane-based TRAPP (m-TRAPP) method in a wide range of temperature and pressure conditions including both subcritical and supercritical regions, in order to obtain thermo-physical properties for hydrocarbon aviation fuels and their products resulting from endothermic reactions. The viscosity and thermal conductivity are predicted in the temperature range from 300 to 1000 K and the pressure from 0.1 to 5.0 MPa, which includes all of the liquid, gas, and the supercitical regions of representative hydrocarbon fuels. The predicted values are compared with those data obtained from the NIST database. It was demonstrated that the m-TRAPP method can give reasonable predictions of both viscosity and thermal conductivity in the wide range of temperature and pressure conditions studied in this paper. However, there still exists large discrepancy between the current data and established values by NIST, especially for the liquid phase. Compared to the thermal conductivity predictions, the calculated viscosities are in better agreement with the NIST database. In order to consider a wide range of conditions, it is suggested to select an appropriate method through further comparison with another improved prediction methodologies of transport properties.