• Steel and Composite Structures
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• 제22권6호
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• pp.1337-1358
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• 2016

The current study focuses on the assessment and interface response of reinforced concrete elements with composite materials (carbon fiber reinforced polymers-CFRPs, glass fiber reinforced polymers-GFRPs, textile reinforced mortars-TRM's, near surface mounted bars-NSMs). A description of the transfer mechanisms from concrete elements to the strengthening materials is conducted through analytical models based on failure modes: plate end interfacial debonding and intermediate flexural crack induced interfacial debonding. A database of 55 in total reinforced concrete columns (scale 1:1) is assembled containing elements rehabilitated with various techniques (29 wrapped with CFRP's, 5 wrapped with GFRP's, 4 containing NSM and 4 strengthened with TRM). The failure modes are discussed together with the performance level of each technique as well as the efficiency level in terms of ductility and bearing/ bending capacity. The analytical models' results are in acceptable agreement with the experimental data and can predict the failure modes. Despite the heterogeneity of the elements contained in the aforementioned database the results are of high interest and point out the need to incorporate the analytical expressions in design codes in order to predict the failure mechanisms and the limit states of bearing capacities of each technique.

• Korean Journal of Materials Research
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• 제2권5호
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• pp.366-374
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• 1992

Mechanical and impact properties of stitched S2 glass fiber reinforced polyester woven laminates composites have been studied. Laminates were stitched using Kevlar 49 thread with 1/2, 1, and 2 inch stitch spacing. Tensile and 3-point bending tests haute been performed to evaluate the mechanical properties of stitched and unstitched laminates. Impact tests at applied energy of 234.7J were performed to examine the impact behavior and toughness changes of the specimen. The same specimens were also tested repeatedly at low impact energy level of 110.2J for 3 times to evaluate damage tolerance properties. The tensile and 3-point bending test results showed that one inch spacing specimen had the highest tensile and flexural strength. It also showed the highest energy absorption capability and the best damage tolerance property at the repeated impact test. The half inch spacing specimen showed the lowest tensile strength and energy absorption property at the impact energy level of 234.7J, even though it had the highest frequency of stitching thread.

• Fibers and Polymers
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• 제2권3호
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• pp.122-128
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• 2001

UV-curable polyurethane acrylate prepolymers were prepared from diisocyanates [isophorone diisocyanate (IPDI), 2,4-toluene diisocyanate (TDI), or 4,4'-dicyclohexylmethane diisocyanate (H$_{12}$MDI)], diols [ethylene glycol (EG), 1,4-butane diol (BD), or 1,6-hexane diol (HD)], polypropylene glycol as a polyol. UY-curable mixtures were formulated from the prepolymer (90 wt%), reactive diluent monomer trimethylol propane triacrylate (10 wt%). and photoinitiator 1-hydroxycy-clohexyl ketone (3 wt% based on prepolymer/diluent). The effects of different diisocyanates/low molecular weigh dial on the dynamic mechanical thermal properties and elastic recovery of UV-cured polyurethane acrylate films were examined. The tensile storage modulus increased a little in the order of EG > BD > HD at the same diisocyanate. Two loss modulus peaks for all samples are observed owing to the glads transition of softs segments ($T_gh$) and the glass transition temperature of hard segments ($T_gh$). For the same diisocyanate, $T_gh$, decreased, however, $T_gh$ increased, in the order of HD > BD > EG. The elastic recovery also increased in the order of HD > BD > EG at the same diisocyanate. In case of same diols, $T_gh$ increased in the order of $H_12$MDl > TDI > IPDI significantly. The ultimate elongation and elastic recovery increased in the order of TDI > IPDI > $H_12$MDl at the same diol.l.

• Textile Coloration and Finishing
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• 제21권1호
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• pp.38-45
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• 2009

First of all, the properties imparted to PET fabrics are resistance to and recovery from creasing or wrinkling when wet or dry; high resistance to stretch in the filament yarns but not in the staple; high abrasion resistance; good texture and appearance; resistance to heat ageing; good chemical resistance and good resistance, behind glass, to sunlight. But, the low moisture regain of PET fabric conduces to static troubles in textile processing. Furthermore, garments made from PET may, during wear, develop electric charges which attract to the fabric particles of soil(dirt, swarf, dust) flying in the air, so that the cuffs of shirts, for example, become soiled quickly and are not easily laundered clean. The sericin constitutes 25$\sim$30％ of silk protein and surrounds the fibroin fiber with sticky layer that supports the formation of a cocoon. The useful biochemical properties of sericin protein are oxidation resistant, antibacterial, UV resistant, hydrophilic property, and good affinity with hydrophobic material. These properties can be used as an improving reagent or a coating agent for natural and synthetic fibers, fabrics, and other intermediate products. The sericin is also applied to cross-link, and can be blended with other materials. In this study, we modified the surface of PET fabric by mixture of sericin finishing agent; sericin, polyuretane binder and 1,2,3,4-butanetetracarboxylic acid (BTCA) cross-link agent. Also, we investigated the finshing effect; moisture regain, stiffness, handle, drape and electrostatic. The moisture regain of PET fabric treated with sericin finishing agent was higher than that of untreated PET fabric. As a result of evaluating influence about handle of PET fabrics treated with sericin finishing agent, it was confirmed that the sericin finishing agent could be use as a linen like finishing agent.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제29권6호
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• pp.804-808
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• 2005

A pneumatic tire is made up of many flexible filaments of high modulus cord of natural textile, synthetic polymer, glass fiber, or fine hard drawn steel embedded in and bonded to a matrix of low modulus polymetric material. Adhesion property of these materials is very important in tire durability safety because belt-leaving-belt tread separation reduces the ability of a driver to control a vehicle, whether or not the separation is accompanied by a loss of air. In this study adhesion test of carcass-belt-tread is conducted on material properties of 5 PCR tire model, which are on sale in domestic market and analyzed adhesion properties. For those tire models FMVSS 109 indoor high speed durability test is conducted to analyze the correlation between adhesion force and high speed performance of tires and found the correlation between the two test results.

• Journal of the Korean Wood Science and Technology
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• 제42권3호
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• pp.282-289
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• 2014

After being laminated with a combination of glass fiber reinforced plastic and plywood, the GFRP laminated plate was densificated for 1 hour at $150^{\circ}C$ with pressure of $1.96N/mm^2$. A partial reinforced beam was produced by attaching the 5 GFRP laminated plates to the joint of glulam and the column. In addition, the column to beam joint was produced by using reinforced laminated wooden pin which was made of GFRP sheet and plywood, fiber glass reinforced cylindrical-LVL column. The joint was made of round log, glulam and drift pin as the reference specimen, and its moment resistance was evaluated. As a result, the strength performance of specimens with partial reinforced beams were 1.8 times stronger than the reference specimen on average. Furthermore, rupture was neither occurred on partial reinforced beam nor column. Toughness and stiffness of joints were also fine. The GFRP sheet reinforced laminated plate showed better reinforcement effect than GFRP textile reinforced one. GFRP sheet was inserted into each layer of laminate, and it showed good condition in rotation-angle and strength, therefore it is the most appropriate to reinforce the part of the beam.

• Textile Coloration and Finishing
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• 제5권4호
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• pp.29-41
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• 1993

In order to surface Hydrophobilization of Poly(ethylene terephthalate) (PET) fiber samples were treated in the atmosphere of CF$_{4}$ or $C_{2}$F$_{6}$glow discharge. The sample used in this study was PET film which is 75$\mu$m thick made by Teijin, O-Type(Japan). The cleaned samples were placed in plasma reactor made of pyrex glass cylinder, and plasma processing was carried out by glow discharge of CF$_{4}$ or $C_{2}$F$_{6}$ gas, being continuously fed by gas flow and continuously pumped out by a vacuum system. Electric power source for generate plasma state was sustained alternating current(60Hz) and voltage was sustained 600 volt. The duration of plasma treatment varied from 15 to 120 seconds except special case, the monomer gase pressure varied from 0.02 to 0.3 Torr and power range was 10 to 90 watts. The hydrophobic features of changed PET surface were evaluated by contact angle measurement and surface chemical characteristics were analyzed by ESCA. Results can be summerized as follows. 1. The most favorable setting position of substrate was the center area between the two electrodes. 2. $C_{2}$F$_{6}$ discharge current was lower than that of CF$_{4}$ when same voltage was sustained. Treated efficiency between CF$_{4}$ and $C_{2}$F$_{6}$ did not revealed significant differences under same electric power(wattage). 3. When monomer pressure is very low below 0.02 torr, as though substrate is exposed to CF$_{4}$ or $C_{2}$F$_{6}$ plasma, it tend to be hydrophilic through a little of fluorine bond and a great deal of oxidizing reaction. 4. There brought good hydrophobilization when monomer pressure was more 0.1 torr and duration of glow discharge treatment was over 45 seconds. When monomer pressure was too high, discharge current became low. Although prolong the duration, there was no more high hydrophobilization. 5. According to ESCA analysis, there were a little CF bond and a prevailing CF$_{2}$ bond in CF$_{4}$-treated substrate. There were CF$_{3}$, a little CF and a prevailing CF$_{2}$ bond in $C_{2}$F$_{6}$-treated substrate.d substrate.

• Fibers and Polymers
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• 제4권1호
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• pp.20-26
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• 2003

The thermal behavior, morphology, ester-interchange reaction of Poly(trimethylene terephthalate) (PTT)/poly(ethylene terephthalate) (PET) melt blends were investigated over the whole composition range(xPTT/(1-x)PET) using a twinscrew Brabender. The melt blends were analyzed by differential scanning calorimetry (DSC), nuclear magnetic resonance spectroscopy ($^{13}{C-NMR}$), and scanning electron microscopy (SEM). Single glass transition temperature ($T_g$) and cold crystallization temperature ($T_cc$) were observed in all melt blends. Melt blends were found to be due to the ester-interchange reaction in PTT/PET blend. Also the randomness of copolymer increases because transesterification between PT and PET increases with increasing blending time This reaction increases homogeneity of the blends and decreases the degree of crystallinity of the melt blends. In PTT-rich blends, mechanical properties decrease with increase of PET content compared with that of pure PTT. And, in PET-rich blends, tensile modulus decreases with increase of PTT content, but tensile strength and elongation is similar to that of pure PET.

• Textile Coloration and Finishing
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• 제27권2호
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• pp.149-154
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• 2015

To investigate the biodegradation of the cellulose powder(CP) derived from Styela clava tunics(SCT), some physico-chemical properties and biodegradability of SCT-CP were measured after the incubation for 45 days. The particles size of SCT-CP prepared with washing, bleaching, drying, and grinding processes was $150-400{\mu}m$ although most of particles (70%) was more than $400{\mu}m$. The cellulose structures of SCT-CP detected using the X-ray diffraction and DSC analysis was very similar with that of wood pulp powder(WP-CP). The glass transition temperature was not detected in both samples. Furthermore, more than 90% of the SCT-CP was degraded, whereas only over 70% of the WP-CP was degraded after the incubation for 45 days. Therefore, these results suggest the possibility that SCT-CP is particularly applicable to prepare medical fiber and film for disease treatment.

• Elastomers and Composites
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• 제46권1호
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• pp.10-21
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• 2011

Recently, with developments in the automotive industry, sound and vibration damping have a considerable attraction with a diversified customer needs and advanced automobile. In general, among various materials, textile materials, such as felt and glass fibers, polyurethane foam, and PET fiber materials were used to reduce sound and vibration of the automobile. These materials were located in various main parts of the automobile to block sound and vibration, resulting in a comfortable ride. In addition, to improve fuel economy, weight reduction and cost saving for the automobile were also being considered together as well as the reduction of sound and vibration of the automobile. Therefore, in this paper, we focused on the need of interior sound and vibration absorption materials in the automobile and absorption materials-related technologies.