• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.61-67
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• 2000

The strengthening method with CFS(Carbon Fiber Sheet) has some fatal defects that the beams strengthened with CFS is always failed far below its ultimated strenth due to rapid progress of horizontal delamination. The crack between beam and CFS are always started from the center of the beam and propagated to the end of the beam. The moment of the beam is always the largest in the middle of the beam, so is the tensile force of the CFS. The bumped surface of the CFS causes debonding force depending on the tensile force of CFS. In this study, two methods which delay early delamination are suggested and proved its validity, experimentally. The first method is using anchor bolt at the end of CFS, and the second method is using CFS wrap aroud at the center and the end of beam. The maximum load and ductility of the two methods are increased significantly. However, the maximum load is still far below the ultimate load. That's because the tensile strength of CFS is so large that its tensile strength can not be reached under normal loading condition. The ductility of the strengthened beam is improved more that twice before modiffication.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.112-117
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• 2016

This research compared the tensile performance of the vegetation mat, which was developed byu using the rapidly growing biodegradable plastic, Poly Lactic Acid(PLA), according to the biodegradation period. The test applied the method defined by Korean Standard KS. In the result of experiment using single-material PLA mesh and PLA plastic, the tensile strength and molecular weight were inverse-proportional to the 5 months of biodegradation period. The thickness of PLA mesh was increased by 11.2~13.4% while the tensile strenth of it was reduced by 32.4~55.4%. The tensile strength and molecular weight of PLA plastic were also reduced over time. However, the tension test of vegetation mat comprised of PLA mesh, non-woven fabric (including seeds), and jute net didn't have specific tendency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1301-1306
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• 2006

Aluminum alloys are gaining increased acceptance in the automotive and electronic industeries and cold & hot forging is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of A6061(Al-1.2Mg-0.8Si) alloy fabricated by cold & hot forging process for development of the future compressor block. The microstructure of cold & hot forginged specimen were composed of eutectic structure aluminum solid solution and $Mg_2Si$ precipitates. The tensile strength of as-solid solution treatment A6061 alloy revealed 291.7MPa. It was fabricated that a trial future compressor cylinder block using cold & hot forging.

• Textile Coloration and Finishing
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• v.7 no.1
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• pp.32-42
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• 1995

In order to reduce the amount of waste water generated from textile dyeing process and processing water, cotton fabric was bleached with ozone in ozone/water contact system, and dyed. The results obtained from the measurement of whiteness, reflectance, tensile strength, color difference, and K/S value of treated samples were as follow : 1) In ozone bleaching, factors affect whiteness most are treatment time and ozone dosage. As treatment time is lengthened, whiteness increases. Futhermore, bleaching effect is high in acidic treatment, but low in alkaline treatment. 2) As bleaching goes on, maximum absorption wave length shifts to shoter wavelengths. 3) As treatment time is lengthened or pH of treatment is low, tensile strenth of treated fabric decrease. 4) In all cases, color difference of dyed cotton fabrics in above 2% o.w.f. dyestuff concentration don't go beyond 1∼2 AN unit, compared with standard.

• International Journal of Reliability and Applications
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• v.5 no.4
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• pp.129-145
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• 2004

We use a novel, forced censoring technique that closer fits the lower tails of strenth distributions to better estimate extremly smaller percentiles for measuring progress in continuous improvement initiatives. These percentiles are of greater interest for companies, government oversight organizations, and consumers concerned with safely and preventing accidents for many products in general, but specifically for medium density fiberboard (MDF). The international industrial standard for MDF for measuring highest quality is internal bond (IB, also called tensile strengh) and its smaller percentiles are crucial, especially the first percentile and lower ones. We induce censoring at a value just above the median to weight lower observations more. Using this approach, we have better fits in the lower tails of the distribution, where these samller percentiles are impacted most. Finally, bootstrap estimates of the small percentiles are used to demonstrate improved intervals by our forced censoring approach and the fitted model. There was evidence from the study to suggest that MDF has potentially different failure modes for early failures. Overall, our approach is parsimonious and is suitable for real time manufacturing settings. The approach works for either strengths distributions or lifetime distributions.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.171-173
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• 2005

Inconel 617 is a solid solution, nickel-chromium-cobalt-molybdenum alloy with an exceptional combination of high temperature strength and oxidation resistance. The combination of high strenth and oxidation resistance at temperatures over $1800^{\circ}F$ makes Inconel 617 an attractive material for such components as ducting, transition liners in both aircraft and gas turbine. In this study, the weldability and weldment characteristics of Inconel 617 are considered in GTAW associated with the two welding current and with back shielding gas using or not. After GTAW with 120A and 150A current, microstructures and hardness test, bending test, tensile test on room and elevated temperature for the determination of optical welding condition.

• Textile Coloration and Finishing
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• v.23 no.2
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• pp.107-117
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• 2011

Polyurethane (PU) was synthesized by one-shot process and the PU nanofiber was prepared by electrospinning. In this study, electrospun PU multi-membranes were prepared with various coating thickness ratio of base resin to top resin, where the base resin contains melamine curing agent and acid catalyst and the top resin contains water-repellent agent of fluoro-carbon compounds. The PU nanofiber multi-membranes were analyzed by field-emission scanning electron microscopy, differential scanning calorimeter, breathability, tensile strenth, air permeability and water resistance. The results showed that the PU multi-membrane provided excellent waterproof and moisture permeability.

• The Korean Journal of Food And Nutrition
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• v.20 no.1
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• pp.1-8
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• 2007

Tortillas were prepared using rice and wheat flour. The experimental design incorporated thee independent variables(rice, wheat flour and moisture content) producing 14 samples of different proportions of each variable for each tortilla. The following were analysed using Design Expert 6 to unveil the influences of these variables on tensile strength and color(L, a, b). Results indicated that tensile strength increased with increasing rice and wheat flour content, however, decreased with increasing moisture content. Lighteness(L), of the tortilla increased with increased rice content whereas yellowness(b) increased with increased wheat flour content. The model suggests that tensile strength and color(L, a, b) in tortillas are highly correlated(SD Comment - give correlation coefficient and p-value). As well, the numerical optimization method suggests that the ratio of wheat flour to rice flour to moisture content which maximizes the three responses(tensile strenth, L and b) is 18.26 : 33.92 : 39.24%, 28.15 : 25.77 : 37.50%.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.685-698
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• 1995

This study was conducted to the effect of temporary cement on the adhesiveness of dentin bonding agent to dentin surface. One hundred freshly extracted bovine mandibular incisors were grinded to expose flat labial dentin surface. The dentin surfaces were temporarized with either eugenol-containing temporary cement(TemBond and Zinc Oxide Eugenol cement) or non-eugenol temporary cement(Nogenol and TempBond NE) for 7days, and then the temporarization was removed with surgical currette and the exposed dentin surfaces were water-rinsed. Bonding specimens were made by use of All-Bond 2 and Super-Bond C&B dentin bonding agent, and stored in $37^{\circ}C$ distilled water for 24hours. The tensile bond strenth and the cohesive failure rate were measured, and then the pretreated dentin surfaces which the temporary cement had been applied to and removed from and the fractured dentin surfaces after bonding test were examined under scanning electron microscope. The results were as follows : In case of bonding with All-Bond 2, tensile bond strength of each experimental group was lower than that of the control group(p<0.05), but there was no significant difference between the bond strengths of the control group and each experimental group in case of bonding with Super-Bond C&B(p>0.05). No significant difference between tensile bond strength of experimental group, whether temporary cement contains eugenol or not, was seen(p>0.05). In case of bonding with All-Bond 2, the control group showed cohesive-adhesive mixed failure mode and the experimental groups mainly showed adhesive failure mode, but in case of bonding with Super-Bond C&B, almost of the control and the experimental groups mainly showed cohesive failure mode. On SEM examination, all of the dentin specimens pretreated with either 10 % phosphoric acid or 10% citric acid after application of the temporary cements demonstrated remnants of temporary cement attached to dentin surface.