• Fashion & Textile Research Journal
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• v.15 no.3
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• pp.444-451
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• 2013

This paper surveys the physical properties of aramid and aramid/nylon hybrid air-jet textured yarns(ATY) for protective garments according to wet and dry texturing conditions. Aramid and nylon filaments were used to make two kinds of para-aramid ATY and four kinds of aramid/nylon hybrid ATY with dry and wet treatments. The analyzed physical properties of six specimens (made on the ATY machine) are as follows. The tenacity and initial modulus of aramid and aramid/nylon hybrid ATY decreased with the wetting and breaking strain; however, the yarn linear density of aramid and hybrid ATY increased with wetting treatment. The dry and wet thermal shrinkage of the hybrid ATY increased with wetting. The stability of aramid and hybrid ATY also increased with wetting. The physical properties of core/effect type hybrid ATY showed significantly more change than the core type hybrid ATY and the physical properties of nylon/aramid core/effect hybrid ATY showed significantly more change than the of aramid/nylon core/effect hybrid ATY. A higher bulky and breaking strain of hybrid ATY require ATY processing conditions of nylon on the core part with wetting and aramid on the effect part. ATY processing conditions for nylon and aramid on the core part with wetting are required for a higher tenacity and modulus. ATY processing conditions of nylon and aramid on the core with no wetting are required for a low thermal shrinkage.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.81-86
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• 1996

The physical properties of epoxy molding compound (EMC) according to the change of softening point of epoxy resin have been investigated in order to study the relationship between the properties of o-cresol novolac epoxy resin, which is main component of EMC for semiconductor encapsulation, and EMC. The softening points of used epoxy resin are 65.1 $^{\circ}C$, 72.2 $^{\circ}C$, and 83.0 $^{\circ}C$, respectively. The flexural strength and flexural modulus as mechanical properties were measured, and thermal expansion coefficient, thermal conductivity and glass transition temperature (Tg) as thermal properties, and spiral flow as moldability have been investigated to see the change of physical properties of EMC. The flexural modulus, thermal expansion coefficients in the glass state (${\alpha}_1$), and thermal conductivity of EMC were found to be keep constant value irrespective of the change of softening point, but Tg increased with softening point of epoxy resin, and the spiral flow decreased with that. It can be considered that these phenomena are due to the increase of crosslinking density of EMC according to the increase of softening point. The transition points were found out in the thermal expansion coefficient data in the rubbery state (${\alpha}_2$) and the flexural strength data. These can show the decrease of filler dispersion according to increase of epoxy resin viscosity.

• Fashion & Textile Research Journal
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• v.1 no.3
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• pp.264-274
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• 1999

The thermal resistance of 60 men's suits for summer and winter was measured to determine their thermal characteristics and physical properties, including air permeability, weight, and thickness of the jackets and trousers consisted of the ensembles were measured to predict the thermal resistance of garments and ensembles. In this study, general physical properties of the men' suit ensembles were determined. In general, thickness and weight of winter ensembles were greater than those of summer ensembles. A factor which could distinguish the difference between summer and winter ensembles was the air permeability. The air permeability of summer ensembles was 3~6 times greater than those of winter ensembles. For the thermal characteristics, the thermal resistance of winter ensembles were higher than those of summer ensembles. When the wind was involved, the thermal resistance of both ensembles decreased up to 30%. In addition, the equations were developed to predict the thermal resistance of the garments and ensembles when there was no air velocity and the thermal resistance of the ensembles with air velocity of 1.2 m/sec. Looking at the equations, thickness, weight, and size of the garments were the definite factors that affect the thermal resistance of the samples.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.250-255
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• 1998

The purpose of this study was to determine physical characteristics, and subjective sensation toward sports socks, varing types of fiber content and fabric structure. Also we tried to develop regression models from variables. Results of this study are as follows. 1. Cotton 100% socks had a highest absorbency and wickability among six different socks. The result of ANOVA shows that fiber content influenced on the wet sensation only prior to exercise. 2. Terry socks had a higher drop absorbency, stretch properties and thermal resistances than plain jersey socks. But there was no significant difference in overall comfort sensation. 3. We developed regression models to predict overall comfort sensation from thermal sensation and wet sensation. Also we can predict thermal sensation from the thickness of socks in the sole area, and we can predict wet sensation from moisture permeability

• Textile Coloration and Finishing
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• v.34 no.4
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• pp.261-271
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• 2022

Waterborne polyurethane(WPU) is greatly affected by its properties depending on the average particle size. In this study, by analyzing the characteristics of WPUs with different average particle sizes according to the DMPA content and we confirmed that the WPU-Ms have different properties from the physical properties of WPU by mixing two types of WPU with different particle sizes in the same volume. At this time, we mixed WPU at an ideal ratio of 7:3 through literature research. In the thermal characteristic analysis, it was confirmed that the thermal decomposition temperature decreased and Tg increased as the content of DMPA, which is the hard segment, increased. In addition, the average particle size of WPU decreased as DMPA increased, and physical properties and adhesive strength were improved due to increased interaction. When mixed with each other in a weight ratio of 7:3, it was observed that adhesion and mechanical properties were improved compared to only WPU.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.554-559
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• 2014

Gadolinium zirconate, $Gd_2Zr_2O_7$, is one of the most promising candidates for replacing yttira-stabilized zirconia (YSZ) in thermal barrier coating (TBC) applications due to its low thermal conductivity and chemical stability at high temperature. In this study, rare-earth zirconate ceramics in the $GdO_{1.5}-ZrO_2$ system with reduced gadolinia contents were fabricated via solid-state reaction as well as hot-pressing at $1800^{\circ}C$. The phase formation, microstructure, and thermo-physical properties of these oxides were examined. The potential application of $GdO_{1.5}-ZrO_2$ ceramics for TBC was also discussed.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.73-81
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• 2013

PURPOSES : In this study, various laboratory tests were performed to investigate basic physical properties of the asphalt concrete which uses wasted vinyl aggregates. METHODS : The thermal conductivity, ultrasonic velocity, Marshall stability, flow, indirect tensile strength were measured according to binder content and wasted vinyl aggregate content. An experimental construction was performed to verify construct ability of the asphalt pavement using the wasted vinyl aggregates. RESULTS : The thermal conductivity and ultrasonic velocity decreased showing insulation effect by mixing more wasted vinyl aggregate, whereas stability and flow increased. The void ratio shows similar value regardless of the mixing ratio. The highest indirect tensile strength was measured at 2.5% of wasted vinyl aggregate content. The construct ability was verified by observing the process of mixing, placing, and compaction and the state of the pavement surface. CONCLUSIONS : The basic properties and construct ability of the asphalt concrete using the wasted vinyl aggregates were verified. The temperature according to pavement depth will be measured to verify the insulation effect of the wasted vinyl aggregates. In addition, amount of snowfall, snowmelt area, and ice adhesion strength will be analyzed quantitively.

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.359-362
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• 2016

Mineral filler is used for resin compounds, because it increases the stiffness and thermal stability of a resin compound, and it also cuts down the cost. Calcium carbonate, silica, magnesium oxide, and others are used as filler materials in general, and the type of filler material, the size, and content can affect the physical properties of compounds. Those factors also influence the viscosity of resin mixtures and the workability, and should be adjusted by changing the contents of the filler, which depends on the size. In this study, five kinds of ground calcium carbonate, which were different in size, were used to produce polyester compounds ; the physical properties were compared with the filler size and contents. The mechanical properties were measured by bending strength and tensile strength, and the heat deflection temperature was obtained for thermal stability.

• Journal of Biosystems Engineering
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• v.9 no.2
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• pp.89-96
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• 1984

This study was intended to search the thermal properties of rice which are necessary in preventing qualitative and quantitative losses in the drying and milling processes. First, the coefficient of cubical thermal expansion of brown rice was measured, which is required for analyzing the internal stress of rice, and then theoretical thermal and moisture stresses were calculated. The results are summarized as follows: 1. The coefficient of cubical thermal expansion of brown rice was about $2.81{\times}10^{-4}/^{\circ}C$ in the temperature range of $10^{\circ}C-60^{\circ}C$. 2. When the shape of brown rice was assumed to be a sphere or a cylinder, maximum thermal stress due to temperature change of $20^{\circ}C-60^{\circ}C$ was in the range of $25-100kg/cm^2$. And maximum moisture stress was in the range of $450-650kg/cm^2$ when the drying temperature was $35^{\circ}C$, initial and final moisture contents of brown rice were 20% and 14% (w.b.), and the moisture diffusion coefficient was assumed to be $6.79{\times}10^{-4}cm^2/hr$. 3. Consequently, it was concluded that crack formation in a rice kernel is mainly caused by moisture stress.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.131-134
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• 2000

Increased temperature adversely affects the reliability of a device. So, package material should have high thermal diffusion, i.e., high thermal conductivity. And, there are several other physical properties of polymeric materials that are important to microelectronics packaging, some of which are a low dielectric constant, a low coefficient of thermal expansion (CTE), and a high flexural strength. In this study, to get practical maximum packing fraction of AIN (granular type) filled EMC, the properties such as the spiral flow, thermal conductivity, CTE, and water resistance of AIN-filled EMC (65-vol%) were evaluated according to the size of AIN and the filler-size distribution. Also, physical properties of AIN filled EMC above 65-vol% were evaluated according to increasing AIN content at the point of maximum packing fraction (highly loading condition). The high loading conditions of EMC were set $D_L/D_S$=12 and $X_S$=0.25 like as filler of sphere shape and the AIN filled EMC in this conditions can be obtained satisfactory fluidity up to 70-vol%. As a result, the AIN filled EMC (70-vol%) at high loading condition showed improved thermal conductivity (about 6 W/m-K), dielectric constant (2.0~3.0), CTE(less than 14 ppm/$^{\circ}C$) and water resistance. So, the AIN filled EMC (70-vol%) at high loading condition meets the requirement fur advanced microelectronic packaging materials.