• 한국산업융합학회 논문집
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• 제11권1호
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• pp.35-40
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• 2008

Various characters of the concrete are greatly improved as the effect of the steel fiber. As the improvement effect of the steel fiber, the increment in flexural strength, shear strength, toughness, and impact strength are remarkable, and tenacious concrete is obtained. This paper presents model which can predict mechanical behavior of the structure according to aspect ratio and volume fraction of steel fiber. Experiments on compressive strength, elastic modulus and tensile strength were performed with self-made cylindrical specimens of variable aspect ratios. This paper presents an analytical study on the behavior of a beam specimen with steel fiber reinforced concrete(SFRC). The effect of the SFRC on the crack pattern, failure mode and the flexural behavior of the structure were investigated. The analysis model based on the nonlinear layered finite element method was successfully able to find the necessary amount of steel fibers, tensile steels and beam section which can best approximate flexural strength and ductility of a given conventionally reinforced concrete beam.

• Journal of Welding and Joining
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• 제32권5호
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• pp.32-43
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• 2014

Welding and joining technology has become a core field. Therefore it is more widely applied to nonferrous metals, inorganic and polymeric materials. That is because the high performance, high function and diversification trend of materials used as industrial technology develops. In the laser welding process, STS 304 and SCP1-S were used as the base materials, the output density was fixed $7MW/cm^2$, the protective gas was argon(Ar) and the transfer rate was fixed 5 mm/sec. and it was progressed while the magnetic field is gradually increasing by 100 mT ranging 0 to 400 mT. The tensile test showed in average about 6 % tensile strength improvement in the case of the laser welding process using the magnetic fields. In the shielded metal arc welding process using SPHC only or the combination of SPHC+STS304 as base materials. The electric current was set at 80 Amperes and the protective gas used argon(Ar) the same as the laser welding process and the strength of magnetic fields. In the shielded metal arc welding process using the magnetic fields, the tensile tests showed about 5 % tensile strength improvement in the case of using SPHC only, 3 % tensile strength improvement in the case of using the combination of SPHC+ STS304. In comparing the results of numerical analysis to the results of experimental tests, it was revealed that the temperature, thermal stress distribution and the behavior of molten pool were similar to those of real tests. Consequently, it may be considered that the numerical assumption and the analytical model used in this study were reasonable.

• 펄프종이기술
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• 제31권4호
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• pp.69-75
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• 1999

This study was performed to investigated the application of mixed resins for corrugated container board. The corrugated container board yields a sandwich structure in which a linerboard material is glued to a corrugated medium . Now, manufacturing corrugated container boards don't provide sufficient strength, and result in box failure during shipping . Therefore improvement of box strength is necessary . In this study, we intend to improve box strength by improving corrugated medium strength with mixed resins and to find the optimum treatment condition of this resins. First, we tried to mixed resins as Starch+CMC, Starch_Irea, CMC+Urea, Second, investigated to applicability of this resins for corrugated medium , and the third, measured tensile index, burst index, and edgewise compression index on liner, medium paper, and single faced corrugated container board. In this test results, we obtained that the improvement ratios of tensile index in liner and medium paper were approximately 80-185%, 60-118% , respectively. The respecting improvement ratios of edgewise compression index of single faced corrugated container board was approximately 91-124%, relatively. In addition, we concluded that optimum condition in mixing ratio was 1 :3 with CMC + Urea and the ap[plication amounts was 9% on materials. Fro manufacture of corrugated container board, optimum condition in mixing ratio was 1 : 3 with 5% CMC +Urea , because of considering to improvement of strength on cost.

• 펄프종이기술
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• 제44권1호
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• pp.58-64
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• 2012

As a first step to apply PVAm (polyvinylamine) on packaging paper by surface treatment, three types of linerboards were impregnated with PVAm solution. The effect of PVAm pick-up on strength properties of linerboard was investigated. The pick-up of PVAm was controlled by varying concentration of PVAm solution. It was found that dry tensile strength, tensile energy absorption, burst strength and compressive strength of linerboard were increased by applying PVAm. In addition, wet tensile strength was significantly improved with increasing PVAm pick-up. However, folding endurance was found to be decreased with increasing PVAm pick-up.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.171-174
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• 2009

This study analyzes the change of the basic characteristics of pavement concrete according to the reinforcement of macro-fiber and the results of the study can be summarized as follows. In the case of the compressive strength of the concrete, the fiber reinforced pavement concrete shows a small decreasing level compared to the basic mixing of pavement concrete (hereafter referred as 'Plain') based on the aging of 28 days. In particular, the polypropylene fiber made in Korea represents a decrease in the strength about 12% compared with that of the Plain. In the case of the tensile strength, it shows certain improvements in the tensile performance compared with that of the Plain. In particular, in the case of the polyvinyl alcohol fiber that shows the largest improvement in tensile performance, it shows an increase in its strength about 21%. In the case of the bending strength, there are no improvements in its strength in the fiber reinforced concrete compared to that of the Plain.

• 전기학회논문지
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• 제67권9호
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• pp.1181-1188
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• 2018

In order to develop new insulating materials for GIS Spacer using environmentally friendly insulating gas, three kinds of dispersed liquid nano composites of solid epoxy /nano layered silicate filled material were prepared. And the epoxy/nano/micro silica composite was prepared by mixing epoxy/nano 3 phr dispersion/4 kinds of filler contents(40,50,60, 70wt%). The electrical insulation breakdown strengths of the nano and nano/micro mixed composites were evaluated by using 8 kinds of samples including the original epoxy. The mechanical tensile strength of the epoxy / nano / micro silica composite were evaluated, also. The TEM was measured to evaluate the internal structure of nano/micro composites. As a result, it was confirmed that the layered silicate nano particles was exfoliated through the process of inserting epoxy resin between silicate layers and the layers. In addition, dispersion of nano / micro silica resulted in improvement of electrical insulation breakdown strength with increase of filling amount of dense tissue with nanoparticles inserted between microparticles. In addition, the tensile strength showed a similar tendency, and as the content of microsilica filler increased, the mechanical improvement was further increased.

• 한국레이저가공학회지
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• 제14권2호
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• pp.1-7
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• 2011

The latest trends of vehicle technology development are fuel efficiency improvement, body designs declining air resistance and lightweight of materials. Especially, as lightened weight of materials makes engine efficient so that vehicles keep the best performance, it is the best way to protect the environment and reduce fuel consumption. In this study, we conducted laser welding by using 3-dimension remote scanner that is 5J32 aluminium alloy. Furthermore, conduction experiment that was 3 times repeated for changing factors such as observing angle, laser power and welding speed. we observed exterior and cross section of weled part and tensile strength. When increasing laser power and decreasing laser speed, tensile strength increased. In order to evaluate factors that affect tensile strength qualitatively we conducted ANOVA. We assumed that the factors are observing angle, laser power and welding speed. Then we found that laser power and laser speed affect tensile strength. We conducted evaluation of weldability of aluminium alloy by above ways.

• Structural Engineering and Mechanics
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• 제92권1호
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• pp.89-97
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• 2024

Discarded cigarette butts in the environment have caused significant pollution. Therefore, providing solutions to address these environmental issues is of great importance. Concrete is known as one of the most widely used materials around the world. Hence, this study investigates the feasibility of using cigarette butts to product concrete. For this purpose, cellulose acetate fibers obtained from cigarette butt filters were added to silica fume concrete in 10 different volume ratios. Then, the mechanical properties of the concrete samples, including compressive strength, Brazilian tensile strength, and flexural tensile strength, were examined. Based on the results, adding fibers to silica fume concrete improved the mechanical properties of the concrete. Among the 10 mixing designs, adding 0.2% by volume of fibers to silica fume concrete yielded the highest compressive and tensile strengths. In other words, adding 0.2% by volume of fibers resulted in a 16% and 34% increase in compressive strength and a 70% and 38% increase in Brazilian tensile strength at 7 and 28 days, respectively, compared to the state without cellulose acetate fibers. Additionally, the flexural tensile stress capacity increased by 56%. Furthermore, the vertical deformation tolerance in beam specimens increased by 287%, and the energy absorption capacity of the concrete beam also significantly increased. Consequently, along with the significant improvement in the mechanical properties of concrete, this study proposes a new and practicalstrategy to addressthe environmental issues caused by waste cigarette butts.

• Geomechanics and Engineering
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• 제16권5호
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• pp.559-567
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• 2018

Technological innovations in sustainable materials for soil improvement have attracted considerable interest due to energy crisis and environmental concerns in recent years. This study presents results of a comprehensive investigation on utilization of nanocarbons in reinforcement of a residual soil mixed with 0, 10 and 20% bentonite. Effects of adding proportionate quantities (0, 0.05, 0.075, 0.1 and 0.2%) of carbon nanotubes and carbon nanofibers to soil samples of different plasticities were evaluated. The investigation revealed that the inclusion of nanocarbons into the soil samples significantly improved unconfined compressive strength, Young's modulus and indirect tensile strength. It was observed that carbon nanofibers showed better performance as compared to carbon nanotubes. The nanosized diameter and high aspect ratio of nanocarbons make it possible to distribute the reinforcing materials on a much smaller scale and bridge the inter-particles voids. As a result, a better 'soil-reinforcing material' interaction is achieved and desired properties of the soil are improved at nanolevel.

• 펄프종이기술
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• 제41권4호
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• pp.65-72
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• 2009

We investigated the effect of polyelectrolyte types in Layer-by-Layer multilayering and furnish combination on physical properties of paper. Handsheets were made from pulp fibers with different polyelectrolytes composition, and their density, formation, tensile strength, strain, tear strength and burst strength were evaluated. The density of handsheet was slightly decreased by polyelectrolyte multilayering. Formation did not show a significant change, but all mechanical properties were increased by polyelectrolyte multilayering. Remarkable improvement in tensile and tear strengths was obtained when pulp fibers were treated with cationic starch and poly styrene 4-sulfonate. Irrespectively of final ionicity of pulp fiber, tensile index, strain and tear strength of paper could be improved simultaneously by polyelectrolyte multilayering.