• Composites Research
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• v.33 no.6
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• pp.329-335
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• 2020

In this study, the thermo-rheological behaivors of petroleum pitches with different softening points were studied, and a B-stage phenolic resins/petroleum pitches blends were prepared by adding petroleum pitches to the phenolic resins. As a result, the petroleum pitch with different softening points decreased the fluidity of the petroleum pitch as the Quinoline insoluble (QI) content increased and showed the viscous properties of the solid. In addition, the effect of adding petroleum pitches having different softening points on the thermo-rheological properties of phenolic resins was investigated. When petroleum pitch with a high softening point was added, the fluidity of the phenolic resin was reduced, and the hardening behavior was fast. It was possible to control the curing rate and curing behavior of the phenolic resin by adding petroleum pitches of different softening points. Among them, the phenolic resin mixture to which P-Pitch 2 was added has a higher fluidity than other blends under the same curing temperature condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.341-342
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• 2012

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.51-58
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• 1995

To prepare a durable softening water repellent, quaternized octadecyl methacrylate-2-diethyl-aminoethyl methacrylate as a mother resin and quaternized 1, 3-dioctadecyl-2, 7-dioxy-6, 8-di(2-hydroxyethyl)-1, 3, 6, 8-tetraazacyclodecane which increase the softening effect and the hydrostatic pressure blended with waxes and their emulsifier in various proportions to give water repellent PADWC. As the results of the measurement of water repellency, washable, tear strength and crease recovery to polyestercotton(P/C) blended fabrics treated with PADWC only or addition of textile finishing resin, the physical properties were increased. There was no significant lowering effect in water repellency when PADWC was treated the antistatic agent by the one-bath method, and the effect of water repellency by the adding the catalyst was studied. PADWC was confirmed as durable water repellent with the results of making little difference of water repellency as ${\pm}5$ point after and before washing.

• Computers and Concrete
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• v.2 no.6
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• pp.499-516
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• 2005

A composite model is used to represent the heterogeneity of plain concrete consisting of coarse aggregates, mortar matrix and the mortar-aggregate interface. The composite elements of plain concrete are modeled using triangular finite element units which have six interface nodes along the sides. Fracture is captured through a constitutive single branch softening-fracture law at the interface nodes, which bounds the elastic domain inside each triangular unit. The inelastic displacement at an interface node represents the crack opening or sliding displacement and is conjugate to the internodal force. The path-dependent softening behaviour is developed within a quasi-prescribed displacement control formulation. The crack profile is restricted to the interface boundaries of the defined mesh. No re-meshing is carried out. Solutions to the rate formulation are obtained using a mathematical programming procedure in the form of a linear complementary problem. An event by event solution strategy is adopted to eliminate solutions with simultaneous formation of softening zones in symmetric problems. The composite plain concrete model is compared to experimental results for the tensile crack growth in a Brazilian test and three-point bending tests on different sized specimens. The model is also used to simulate wedge-type shear-compression failure directly under the loading platen of a Brazilian test.

• Advances in concrete construction
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• v.1 no.1
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• pp.1-27
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• 2013

Discrete steel fibres can increase significantly the bending and the shear resistance of concrete structural elements when Steel Fibre Reinforced Concrete (SFRC) is designed in such a way that fibre reinforcing mechanisms are optimized. To assess the fibre reinforcement effectiveness in shallow structural elements failing in bending and in shear, experimental and numerical research were performed. Uniaxial compression and bending tests were executed to derive the constitutive laws of the developed SFRC. Using a cross-section layered model and the material constitutive laws, the deformational behaviour of structural elements failing in bending was predicted from the moment-curvature relationship of the representative cross sections. To evaluate the influence of the percentage of fibres on the shear resistance of shallow structures, three point bending tests with shallow beams were performed. The applicability of the formulation proposed by RILEM TC 162-TDF for the prediction of the shear resistance of SFRC elements was evaluated. Inverse analysis was adopted to determine indirectly the values of the fracture mode I parameters of the developed SFRC. With these values, and using a softening diagram for modelling the crack shear softening behaviour, the response of the SFRC beams failing in shear was predicted.

• Journal of the Korean Ceramic Society
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• v.22 no.4
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• pp.47-53
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• 1985

Various amount of $P_2O_5$ were added to $PbO-B_2O_3$ binary glass system to investigate its effect on the phase separation and physical properties of the glass. Experiments such as infrared spectroscopy scanning electron microscopy thermal expansion softening point and microhardnesses were done. Phase separation with $B_2O_3$ rich phase matrix and PbO rich phase droplet was observed for the glasses con-taining less than 10m/o of PbO while the opposite morphology of phase separation for the glasses containing more than 11m/o of PbO. By adding increasing amount of $P_2O_5$ their phase separation region was extended to the glass containing more than 20m/o of PbO. These effects can be interpreted in terms of the inoic field strength difference of each ions in the glasses. The abrupt changes of physical properties such as softening point thermal expansion and microhardness were observed for the glass with around 10m/o of PbO in this system. These changes are by the matrix composition change from TEX>$B_2O_3$ rich phase to PbO rich phase depending on PbO concentration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.396-399
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• 2004

저온 동시소성용 glass-ceramics의 소결 경향성 연구를 위해 lead-borosilicate계 glass를 frit화하여 알루미나분말과 $TiO_2$분말을 $10{\sim}50\;vol%$로 각각 혼합한 후 여러 온도에서 소결하여 소결과 유전 특성을 조사하였다. 그 결과 glass의 연화온도(Ts)가 낮을수록 최대 치밀화 온도가 낮았으며, 반면에 소결밀도는 Ts가 높을수록 높았는데, 이는 glass-ceramicss에서의 결정화도와 관계하였다. 본 연구를 통해 glass-ceramic에서의 소결특성은 glass와 ceramic의 반응성에 의한 2상 석출 정도에 큰 영향을 받음을 알 수 있었으며, ceramic filler로서 알루미나와 $TiO_2$를 이용하여 $900^{\circ}C$에서 소성이 가능하였다. 알루미나의 경우 유전특성$({\epsilon}r=8.5,\;Q{\times}fo=6000)$이 기판용 저유전율 재료로 사용이 가능하였고, $TiO_2$의 경우도 유전특성($({\epsilon}r=17,\;Q{\times}fo=4000)$)이 필터용 고유전율 재료로 사용 가능하도록 높게 나타났다.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.609-614
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• 2009

The low-temperature preparation of porous ceramics was carried out using mixtures of alumina-zinc borosilicate (ZBS) glass. The compositions of alumina-ZBS glass mixture with PMMA pore-former were unfortunately densified. Because PMMA was evaporated below the softening point of ZBS glass ($588{^{\circ}C}$), the densification through the pore-filling caused by the capillary force might occur. Howerver, those with carbon possessed pores where carbon was evaporated above the softening point. The porous ceramic having 35% porosity was successively fabricated by the low-temperature sintering process below $900{^{\circ}C}$ using 45 vol% of alumina, 45 vol% ZBS of glass, and 10 vol% of carbon as starting materials.

• Carbon letters
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• v.15 no.4
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• pp.262-267
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• 2014

Pyrolized fuel oil (PFO) was reformed by novel electron beam (E-beam) radiation, and the elemental composition, chemical bonds, average molecular weight, solubility, softening point, yields, and density of the modified patches were characterized. These properties of modified pitch were dependent on the reforming method (heat or E-beam radiation treatment) and absorbed dose. Aromaticity ($F_a$), average molecular weight, solubility, softening point, and density increased in proportion to the absorbed dose of E-beam radiation, with the exception of the highest absorbed dose, due to modification by free radical polymerization and the powerful energy intensity of E-beam treatment. The H/C ratio and yield exhibited the opposite trend for the same reason. These results indicate that novel E-beam radiation reforming is suitable for the preparation of aromatic pitch with a high ${\beta}$-resin content.

• Geomechanics and Engineering
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• v.2 no.3
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• pp.191-202
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• 2010

The porosity (including the specific surface area and pore volume-diameter distribution) of montmorillonitic soft rock (MSR) was studied experimentally with an electrochemical treatment, based on which the change in porosity was further analyzed from the perspective of its electrokinetic potential (${\zeta}$ potential) and the isoelectric point of the electric double layer on the surface of the soft rock particles. The variation between the ${\zeta}$ potential and porosity was summarized, and used to demonstrate that the properties of softening, degradation in water, swelling, and disintegration of MSR can be modified by electrochemical treatment. The following conclusions were drawn. The specific surface area and total pore volume decreased, whereas the average pore diameter increased after electrochemical modification. The reduction in the specific surface area indicates a reduction in the dispersibility and swelling-shrinking of the clay minerals. After modification, the ${\zeta}$ potential of the soft rock was positive in the anodic zone, there was no isoelectric point, and the rock had lost its properties of softening, degradation in water, swelling, and disintegration. The ${\zeta}$ potential increased in the intermediate and cathodic zones, the isoelectric point was reduced or unchanged, and the rock properties are reduced. When the ${\zeta}$ potential is increased, the specific surface area and the total pore volume were reduced according to the negative exponent law, and the average pore diameter increased according to the exponent law.