• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.337-340
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• 2005

In this study, an effect of fiber blending on material property of Hybrid Fiber Reinforced Concrete (HFRC) was evaluated. Also, Compare and evaluates collating and mechanical property by the mixing rate of fiber for HFRC was determine. Modulus of rupture and strength effectiveness of Hybrid Fiber Reinforced Concrete mixed with macro-fiber(steel fiber) and micro-fiber(glass fiber, carbon fiber, cellulose fiber). Test result shows, in the case of mono fiber reinforced concrete. As the steel fiber mixing rate increases to 1.5$\%$, the strength effectiveness promotion rate rises. However, when is 2.0$\%$, strength decreases. In the case of hybrid fiber reinforcement concrete, synergy effect of micro fiber and macro fiber happens and higher Modulus of rupture and strength effectiveness appears than mono-fiber reinforcement concrete. Use of hybrid fiber reinforcement in concrete caused a significant influence on its fracture behavior; consequently, caused increase by mixing rate of steel fiber + carbon fiber and contributed by steel fiber + glass fiber, steel fiber + celluloid fiber in reinforcement effect in order. And was expose that steel fiber(1.5$\%$) + carbon fiber(0.5$\%$) is most suitable association.

• Journal of the Korean Ceramic Society
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• v.32 no.9
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• pp.989-994
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• 1995

Rigid porous carbon fiber composites with the uniform pore size distribution were prepared by vacuum forming from water slurries containing carbonized PAN fibers, a phenolic resin and ceramic binders. The composites were designed to use for highly efficient carbon fiber filters for particulate filtration and gas adsorption. As the as-received carbon fibers of 1mm in length were milled to an approximate average length of 300${\mu}{\textrm}{m}$, modulus of rupture (MOR) of the composite filter was increased from 1MPa to the value larger than 5 MPa. Modulus of rupture (MOR) for the composite filter fabricated using the milled carbon fiber was increased from 5 MPa to 10 MPa as the carbonization temperature of the PAN fiber was raised from 90$0^{\circ}C$ to 140$0^{\circ}C$. The air permeability and an average pore size of the composite filter were increased from 40 to 270cc/min.$\textrm{cm}^2$ and from 35 to 80${\mu}{\textrm}{m}$, respectively, as the apparent porosity increased from 80 to 95%. It was shown that the MOR of the carbon fiber composite filter was dependent primarily on the average length of carbon fiber, carbonization temperature and the type of bonding materials.

• Journal of the Korean Ceramic Society
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• v.20 no.4
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• pp.347-355
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• 1983

A batch mixture was prepared as 16mol% CaO-84mol% $ZrO_2$ of regeant-grade powder. The monoclinic Zirconia powder had an average particle size of $9.24 \mu\textrm{m}$ and calcium carbonate powder had a reported purity of 99.7 weight percent and mean particle size of TEX>$24, 37<\mu\textrm{m}$. The specimens were fired at 1400, 1500, 1650 and $1750^{\circ}C$ for 0. 3, 5 and 7 hours respectively. After fired the specimens were investigated using Scaning electron microscopy. Density Porosity Compressive strength Modulus of rupture and Thermal expansion were measured X-ray diffration analysis was also carried out. The results are as follows ; 1) As the firing temperature or soaking time was increased firing linear shrinkage apparent density compressive strength and modulus of rupture increased but apparent porosity decreased, 2) Cubic and monoclinic Zirconia was found at $1400^{\circ}C$ and cubic Ziconia found above $1500^{\circ}C$ 3) The specimens fired at 140$0^{\circ}C$ without soaking display thermal expansion curves by monoclinic〓tetragonal transformation and no tranformation was found at $1400^{\circ}C$ for 5hrs and above $1500^{\circ}C$. 4) The lattice parameter had constant value of 5.1345 $\AA$ through all the ranges of firing temperature 5) The higher the firing temperature was or the longer the soaking time was the larger the grain size was.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.364-373
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• 2015

This study was carried out to estimate the effects of density and mixing ratio of mandarin peels on the bending performances of the sawdust-mandarin peels particle boards. The board density influenced significantly to the bending performance of boards. Dynamic modulus of elasticity (dMOE) and static modulus of elasticity (sMOE) and modulus of rupture (MOR) of particle boards decreased with an increase in the mixing ratio of mandarin peels at the board densities of $0.4g/cm^3$ and $0.5g/cm^3$. High correlations were found between the dMOE and sMOE, and dMOE and MOR of particle boards prepared. Therefore, it was concluded that the dMOE obtained by free vibration test using resonance frequency could be used for predicting the sMOE and MOR of sawdust-mandarin peels particle boards.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.86-89
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• 2015

Sugar cane, renewable fiber resources, were used for roof tile production. Urea formaldehyde, phenol formaldehyde and isocyanate resin were used as binders in this study. Roof tile specimens with 400 mm wide, 400 mm long and 5 mm thick were prepared by compression molding. Physical and mechanical properties of the specimens were analyzed by water absorption, thickness swelling, thermal conductivity, density, modulus of rupture and modulus of elasticity. From the results, water absorption at 1 and 24 hours was 19-47 % and 38-57 %, respectively. Thickness swell at 24 hours was 15-29%. Thermal conductivity was 0.016, 0.017 and 0.019 W/m.K when using isocyanate, urea formaldehyde and phenol formaldehyde, respectively. Density of the specimens was 770-860 kg/m3. Modulus of rapture was 255-280 MPa. Modulus of elasticity was 5.1-7.6 GPa. Physical and mechanical properties of the specimens indicated that they would be applied for roof tile and construction.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.36-42
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• 2015

This study examined true modulus of elasticity (MOE) and modulus of rigidity (G) for domestic woods with different slenderness ratios (L/D) using the static bending and stress wave tests. Bending properties of small clear wood specimen of three domestic wood species were determined at 12% moisture content. The results of this study indicated that both MOR and MOE of domestic woods were affected by the slenderness ratio. As the slenderness ratio increased, MOR and MOE increased. G and true MOE of domestic timber beams were obtained at different slenderness ratios by flexure test and stress wave test. The values reported here can be useful if these species woods are used for structural purposes. However, the reported values are only indicative and do not represent the true average of wood species due to the limited number of specimens tested.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.533-542
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• 2000

Instrumentation and technologies are described for determining the vibration response characteristics of the pear with frequency range 5 to 320Hz. The computer program for controlling the vibration exciter and the function generator and for measuring the vibration response characteristics of the pear was developed. Mechanical properties such bioyield deformation, rupture deformation and apparent elastic modulus etc. were compared with the vibration response characteristics of the pear. The resonant frequency of the pear ranged from 53 to 102Hz and the amplitude at resonance was between 1.08 and 2.48g-rms. The resonant frequency and amplitude at resonance decreased with the increase of the sample mass, and they were slightly affected by mechanical properties such as bioyield deformation and rupture deformation. Regression analysis was performed among the relatively high correlated parameters from the results of correlation coefficient analysis.

• Journal of the Korean Ceramic Society
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• v.17 no.1
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• pp.27-34
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• 1980

The synthesis of glass-ceramic materials from glasses based on industrial wastes or natural rocks their physical properties were studied. Glasses of composition, CaO14.7∼16.1, MgO7.4∼9.0, Al2O38.3∼19.3, SiO2 48.9∼51.0wt% were prepared from domestic blast furnace slag, serpentine, sea sand and etc. with additions of chromic oxide, and fluoride as nucleating agent. The glasses were subjected to controlled heat treatments and yielded fine microstructure of glass-ceramics which were composed of monocrystalline phase of aluminous diopside. X-ray diffraction techniques were adopted to identify the crystalline phases and to determine the degree of crystallization quantitatively. Density, coefficient of thermal expansion, young's modulus, microhardness and modulus of rupture were measured and the resulting properties were discussed in terms of the heat-treatment conditions, the degree of crystallization, species of crystaline phase, the microstructures formed in glass-cramics and the chemical compositions of mother glasses.

• Journal of the Korea Furniture Society
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• v.27 no.4
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• pp.302-308
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• 2016

It has been known that acetylation improves the dimensional stability of wood. Liquid phase acetylation is more popular than gas-phase acetylation for the effectiveness of weight gain of wood. In this study the specimens of domestic red and Korean pines are acetylated in liquid phase and their physical properties, such as density, bending strength, anti-hygroscopicity etc., are analyzed. Acetylation increases the average weights and volume of larch specimens by 11.4% and 3.4%, respectively, and their average oven-dry densities are increased by $0.03g/cm^3$. Acetylation does not influence on Modulus of Rupture (MOR) and Modulus of Elasticity (MOE). The average Percentage Reduction in Hygroscopicity (PRH) and average Percentage Reduction in Water soaking (PRW) of larch specimens are respectively 20.2% and 20.8%. Thus it can be concluded that acetylation improves the dimensional stability of larch specimens.

• International Journal of Concrete Structures and Materials
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• v.7 no.1
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• pp.61-69
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• 2013

This paper discusses the properties of RCA, the effects of RCA use on concrete material properties, and the large scale impact of RCA on structural members. The review study yielded the following findings in regards to concrete material properties: (1) replacing NA in concrete with RCA decreases the compressive strength, but yields comparable splitting tensile strength; (2) the modulus of rupture for RCA concrete was slightly less than that of conventional concrete, likely due to the weakened the interfacial transition zone from residual mortar; and (3) the modulus of elasticity is also lower than expected, caused by the more ductile aggregate. As far as the structural performance is concerned, beams with RCA did experience greater midspan deflections under a service load and smaller cracking moments. However, structural beams did not seem to be as affected by RCA content as materials tests. Most of all, the ultimate moment was moderately affected by RCA content. All in all, it is confirmed that the use of RCA is likely a viable option for structural use.