• Journal of Fashion Business
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• v.7 no.4
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• pp.121-128
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• 2003

A new textile material, poly(trimethylene terephthalate) polymer, has been introduced to the textile industry. The structure of PTT is similar to the PET, while the tensile deformation and subsequent recovery property is better than that of PET. In this study, the physical and mechanical properties of textile woven fabrics made of PTT, PET, and nylon 6 yarns as the filling yarn were determined using the Kawabata Evaluation System (KES), including tensile, bending, shearing, compression, and surface related parameters. On top of these measurements, the subjective ratings by evaluators were performed on the fabric samples. From the examination of the stress-strain behavior of the yarn specimens focused on the recovery mode, it was evident that the PTT specimen developed lower stress at 3% elongation. The subsequent recovery curve showed that the PTT has less stress-decay rate than the other specimens, implying that the recovery behavior of the PTT is recommendable for the end-uses including stretchable textile materials, sports wears, etc. The KES bending rigidity(B) value of the PTT sample fabric was lower than that of the PET sample fabric. Subjective evaluation of the fabric samples by the evaluators on the descriptive word pair "soft - not soft" showed similar tendency with the KES B determination of the fabric samples.

• Membrane Journal
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• v.20 no.3
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• pp.235-240
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• 2010

The aim of this paper is to evaluate and compare the performances of forward osmosis (FO) membranes using different materials. The FO membranes were synthesized using interfacial polymerization method on hydrophobic polysulfone (PSf) and relatively hydrophilic polyethersulfone (PES) supports. The FO performance such as flux and back diffusion was measured. The resulting fluxes of PSf and PES FO membranes were $4.3\;L/m^2hr$ and $17.8\;L/m^2hr$, respectively. The flux of the PES FO membrane was higher than that of the PSf FO membrane. The results indicated that hydrophillictity of the support membrane is important for increasing flux in FO process. Moreover, with decreasing the support layer thickness, flux increased considerably.

• Membrane Journal
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• v.23 no.2
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• pp.176-184
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• 2013

To investigate the performance of VOC separation, composite hollow fiber membrane was prepared which composed of poly (ether imide) support prepared by phase separation method and poly (dimethylsiloxane) coating active layer. The performances of the membranes for the application of recovery process in terms of their morphology, gas permeance test for $N_2$ and $O_2$ gases. Durability against benzene, toluene and xylene was also investigated. And permeation test for multi-component VOCS through the membrane with different feed concentration and stage-cut were investigated. Permeance of PEI supported membrane and the membranes coated with PDMS decreased from 45,000 GPU to 63 GPU and 49,450 to 30 GPU for $N_2$ and $O_2$, respectively. Recovery efficiency and concentration of VOCs in permeate increased with decreasing stage-cut. VOCs concentration in permeate proportionally increased with increasing feed concentration but concentration ratio and recovery efficiency showed any noticeable changes with feed concentration change.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.4 s.193
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• pp.138-146
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• 2007

Some biodegradable polymers and other materials such as hydrogels have shown the promising potential for surgical applications. Post surgical adhesion caused by the natural consequence of surgical wound healing results in repeated surgery and harmful effects. Recently, scientists have developed absorbable anti-adhesion barriers that can protect a tissue from adhesion in case they are in use; however, they are dissolved when no longer needed. Although these approaches have been attempted to fulfill the criteria for adhesion prevention, none can perfectly prevent adhesions in all situations. Overall, we developed a new method to fabricate an anti-adhesion membrane using biodegradable polymer and hydrogel. It employed a highly accurate three-dimensional positioning system with pressure-controlled syringe to deposit biopolymer solution. The pressure-activated microsyringe was equipped with fine-bore nozzles of various inner-diameters. This process allowed that inner and outer shapes could be controlled arbitrarily when it was applied to a surgical region with arbitrary shapes. In order to fulfill the properties of the ideal barriers f3r preventing postoperative adhesion, we adopted the pre-mentioned method combined with surface modification with the hydrogel coating by which anti-adhesion property was improved.

• International Journal of Highway Engineering
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• v.17 no.3
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• pp.77-83
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• 2015

PURPOSES : In this study, a fracture-based finite element (FE) model is proposed to evaluate the fracture behavior of fiber-reinforced asphalt (FRA) concrete under various interface conditions. METHODS : A fracture-based FE model was developed to simulate a double-edge notched tension (DENT) test. A cohesive zone model (CZM) and linear viscoelastic model were implemented to model the fracture behavior and viscous behavior of the FRA concrete, respectively. Three models were developed to characterize the behavior of interfacial bonding between the fiber reinforcement and surrounding materials. In the first model, the fracture property of the asphalt concrete was modified to study the effect of fiber reinforcement. In the second model, spring elements were used to simulated the fiber reinforcement. In the third method, bar and spring elements, based on a nonlinear bond-slip model, were used to simulate the fiber reinforcement and interfacial bonding conditions. The performance of the FRA in resisting crack development under various interfacial conditions was evaluated. RESULTS : The elastic modulus of the fibers was not sensitive to the behavior of the FRA in the DENT test before crack initiation. After crack development, the fracture resistance of the FRA was found to have enhanced considerably as the elastic modulus of the fibers increased from 450 MPa to 900 MPa. When the adhesion between the fibers and asphalt concrete was sufficiently high, the fiber reinforcement was effective. It means that the interfacial bonding conditions affect the fracture resistance of the FRA significantly. CONCLUSIONS : The bar/spring element models were more effective in representing the local behavior of the fibers and interfacial bonding than the fracture energy approach. The reinforcement effect is more significant after crack initiation, as the fibers can be pulled out sufficiently. Both the elastic modulus of the fiber reinforcement and the interfacial bonding were significant in controlling crack development in the FRA.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.95-103
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• 2013

PURPOSES : To investigate the fundamental characteristics of blast-furnace slag mortar that was hardened with activating chemicals to capture and sequester carbon dioxide. METHODS : Various mix proportions were considered to find an appropriate stregnth development in regards with various dosages of activating chemicals, calcium hydroxides and sodium silicates, and curing conditions, air-dried, wet and underwater conditions. Flow characteristics was investigated and setting time of the mortar was measured. At different ages of 3, 7 and 28days, strength development was investigated for all the mix variables. At each age, samples were analyzed with XRD. RESULTS : The measured flow values showed the mortar lost its flowability as the activating chemicals amount increased in the scale of mole concentration. The setting time of the mortar was relatively shorter than OPC mortar but the initial curing condition was important, such as temperature. The amount of activating chemicals was found not to be critical in the sense of setting time. The strength increased with the increased amount of chemicals. The XRD analysis results showed that portlandite peaks reduced and clacite increased as the age increased. This may mean the $Ca(OH)_2$ keeps absorbing $CO_2$ in the air during curing period. CONCLUSIONS : The carbon capturing and sequestering activated blast-furnace slag mortar showed successful strength gain to be used for road system materials and its carbon absorbing property was verified though XRD analysis.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.247-247
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• 1999

The segregation (distribution) of nickel and the composition of its constituents influence the low thermal expansion characteristics (Invar effect) in Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy. The change of coefficient of the thermal expansion and magnetic properties were studied as an aspect of carbon addition causing the segregation of Ni in primary austenite of as-cast Fe-30 wt.% Ni-12.5 wt.% Co Invar alloy. The coefficient of thermal expansion of Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy showed its lowest value at 0.08 wt.% carbon, increased with increasing carbon content in the range of 0.08-1.0 wt.%C, kept constant at 1.0-2.0 wt.%C and decreased at carbon higher than 2.0 wt.%. The effective distribution of the coefficient of nickel in as-cast Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy increased with increasing carbon content. The volume fraction of they phase of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy increased with increasing carbon content. The microstructure of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy changed with the carbon content was independent of the coefficient of thermal expansion. The Curie temperature changed linearly with the carbon content and was similar to the change of the coefficient of thermal expansion. Moreover, the coefficient of thermal expansion decreased when the ratio of saturation magnetization to Curie temperature ($\sigma_s/T_c$) increased, decreasing the Curie temperature and showed a specific relationship with the magnetic properties of the Fe-30 wt.% Ni-12.5 wt.% Co-xCInvar alloy.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.241-241
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• 1999

With the aim of assessing the degradation of Zr-2.5Nb pressure tubes operating in the Wolsong unit-1 nuclear power plant, characterization tests are being conducted on irradiated Zr-2.5Nb tubes removed after 10-year operation. The examined tube had been exposed to temperatures ranging from 264 to 306℃ and a neutron fluence of 8.9×$10^{21}$ n/cm²(E>1 MeV) at the maximum. Tensile tests were carried out at temperatures ranging from RT to 300℃. The density of a-type and c-type dislocations was examined on the irradiated Zr-2.5Nb tube using a transmission electron microscope. Neutron irradiation up to 8.9×$10^{21}$ n/cm²(E>1 MeV) yielded an increase in a-type dislocation density of the Zr-2.5Nb pressure tube to 7.5×$10^{14} m^{-2}$, which was highest at the inlet of the tube exposed to the low temperature of 275℃. In contrast, the c-component dislocation density did not change with irradiation, keeping an initial dislocation density of 0.8×$10^{14} m^{-2}$ over the whole length of the tube. As expected, the neutron irradiation increased mechanical strength by about 17-26% in the transverse direction and by 34-39% in the longitudinal direction compared to that of the unirradiated tube at 300℃. The change in the mechanical properties with irradiation is discussed in association with the microstructural change as a function of temperature and neutron fluence.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.14-20
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• 2001

On the bending process, metal-strap plays an important role in dispersing the stress generated in wood. Therefore, the metal-strap has more influence on the property of bentwood materials. The effect of the metal-strap thickness for bentwood was examined. The effect of metal-strap on the bending properties of Korean red pine(Pinus densiflora Sieb. et Zucc.)was investigated in this research. The metal-strap thickness is divided into 4 kinds such as 1.0, 0.8, 0.6, 0.4 mm. The specimens were selected by grain such as annual ring angles, flat grain and half-edge grain specimens. As a result of this study, the bending ability of 1.0, 0.8 mm, thickness of half-edge grain specimens was better than flat grain specimens but the result of 0.6, 0.4 mm were reversed. The bending ability of half-edge grain was better than flat grain and the grade was higher. When the processed specimens were dried, the radius of curvature(ROC) was decreased became drying-stress was not perfectly dispersed. An optimum drying-condition would deminish this phenomenon.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.52-57
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• 2003

The charcoal is known to have gas adsorption capability and electrical properties. Some practical applications of carbon materials for the purpose of limited electrical conduction were made in these days. In this paper, we applied the several different kinds of charcoal to the papers in three different ways to investigate if charcoal application method affects its electrical conduction capability. Wet end addition, making multiply, and coating method were tested. The area electrical resistivity of charcoal containing paper was measured. The strength properties of charcoal containing paper were compared to those of the control, which had no charcoal in it. Experimental results showed that manufacturing conditions of the charcoal itself changed its electrical and strength properties of charcoal containing paper. The electrical properties of charcoal containing paper can be used for the removal of electrostatic problem in packaging system. The strength property of the charcoal containing paper should be kept, at least, over the minimum requirement for the packaging system. By using coating method on paper or making multiply, strength loss of paper by inclusion of charcoal could be overcome.