• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.23-29
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• 2009

The hybrid composite materials are recently used in many field as an advanced material due to their high resistance to fracture. However, hybrid composite materials have several problems, especially delamination, compared with homogeneous materials such as an aluminum alloy, etc. In this study, we carried out the tensile test to study the tension failure appearances and tensile ultimate strength of CFRP/Al/CFRP hybrid composite materials. The CFRP material used in the experiment is a commercial material known as CU175NS in unidirectional carbon prepreg. Also Al/CFRP/Al hybrid composites with three kind length of a single edge crack were investigated for the relationship between an aluminium volume fraction and a crack length. The crack length was measured by a traveling microscope under a universal dynamic tester. Futhermore the stress intensity factor behavior was examined according to a volume fraction and an initial crack length ratio to a width.

• Advances in concrete construction
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• v.7 no.4
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• pp.249-262
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• 2019

In this study, high strength aluminum alloys (AA) plates are proposed as a new construction material for strengthening reinforced concrete (RC) beams. The purpose of this investigation is to evaluate AA plate's suitability as externally bonded reinforcing (EBR) materials for retrofitting shear deficient beams. A total of twenty RC beams designed to fail in shear were strengthened with different spacing and orientations. The specimens were loaded with four-points loading till failure. The considered outcome parameters included load carrying capacity, deflection, strain in plates, and failure modes. The results of all tested beams showed an increase up to 37% in the load carrying capacity and also an increase in deflection compared to the control un-strengthened beams. This demonstrated the potential of adopting AA plates as EBR material. Finally, the shear contribution from the AA plates was predicted using the models available in the ACI440-08, TR55 and FIB14 design code for fiber reinforced polymer (FRP) plates. The predicted results were compared to experimental testing data with the ratio of the experimentally measured ultimate load to predicted load, range on the average, between 93% and 97%.

• Textile Coloration and Finishing
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• v.32 no.4
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• pp.199-207
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• 2020

Recently, as the demand for masks increases, the use of filter-replaceable cotton masks is increasing. A filter-replaceable cotton mask is one of the ways to solve the environmental problems of a disposable nonwoven mask because only the filter can be replaced after washing. Cotton fiber products are known to be environmentally friendly, but cotton products dyed with general synthetic dyes are not safe for humans. In this study, to prepare of cotton mask applied with natural dyeing, the optimal dyeing conditions are set when dyeing with gallnut extract. A polychromatic natural dye that changes color by mordant, and the functionalities of gallnut dyeing fabrics are evaluated. The experimental method is dyed the gallnut by temperature and time by concentration to set the optimal conditions. The color fastness rating grade of aluminium potassium sulfate dodecahydrate, copper(ll) sulfate pentahydrate, and iron(ll) chloride tetrahydrate were evaluated after the pre/post mordanting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8447-8454
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• 2015

ISO 12215-5 standard describes allowable stress design specifications of monohull small boat with a length of hull between 2.5 m and 24 m constructed from fiber reinforced plastics, aluminium or steel alloys, glued wood or other suitable boat building material. If small boat hull is under 2.5m in overall length or nonstandard material is used as boat building material, structural reliability of small boat hull is assured by drop test specification, but not by structural design specification in accordance with ISO 12215-5. Drop test specification of boat hull can be applied to manufactured product. But it is difficult and complicated to apply drop test specification to structural design of boat hull. In this study, we present structural design method of polyethylene boat hull on the basis of longitudinal bending strength test specification.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.151-156
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• 2018

In this study, CFRP and metal or nonmetal were bonded with adhesive and the fracture study on this material was carried out. CFRP at the upper side of specimen and metal or nonmetal were assigned at the lower side of specimen by using DCB specimen as the analysis condition. And it was desribed that the structural adhesive were bonded between both upper and lower sides. As this analysis result, the least equivalent stress was shown at the specimen bonded with aluminium. The maximum shear stress was shown to become lowest at the de-bonded CFRP specimen when titanium was used. In conclusion, it was shown that the deformation of specimen became lowest when titanium was used. On the basis of this study result, the esthetic sense can be shown as the fracture data of bonded interface using adhesive are grafted onto the real life.

• Korean Journal of Human Ecology
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• v.21 no.4
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• pp.791-803
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• 2012

This study intends to identify applicability of natural dye extracted from Aplysia kurodai, aiming to standardization of Aplysia kurodai natural dyeing through scientific validation by analyzing characteristics of pigment elements to review dyeability, colorfastness and antibacterial activity. Such material as silk fabrics that is animal fiber were used for this purpose, and derived following summarized results. UV/VIS spectrum analysis on the pigment of Aplysia kurodai that was extracted from purple gland showed that maximum absorbtion was near 540 nm. The silk fabric optimal dyeing can be achieved at a temperature of $55^{\circ}C$ with a colorant concentration of 5%. Dyed at $55^{\circ}C$ with interval of 10~90 minutes for identifying dye uptake over time to observed slow increase of dye uptake over time, and equilibrium occurred at 50 minutes. For dye uptake according to pH, while dye uptake was superior in acidity, it decreased rapidly in a base after pH 7. For color changes according to pH variation, it was reddish purple in acidity and was purplish red in a base. For color changes according to mordanting method, more clear color change had been obtained when process with aluminium pre-mordanting than non-mordanting and post-mordanting. The colorfastness to light, perspiration and washing was 1, 4~5, and 3~4 ratings respectively. The silk fabric dyed with Aplysia kurodai demonstrated excellent antimicrobial activity to Staphylococcus aureus and Klebsiella pneumoniae. The Aplysia kurodai can be used as a new colorant for the natural dyeing of silk.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.16-21
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• 2012

In this study, the strength safety for 110 liter hydrogen fuel storage tank with 70MPa filling pressure has been analyzed using a FEM technique. The strength safety of a composite fuel tank in which is fabricated by an aluminum liner of 6061-T6 and carbon fiber wound composite layers of T800-24K and T700-12K of Toray, and MR60H-24P of Mitsubishi Ray has been investigated based on the criterion of a strength safety of US DOT-CFFC and Korean Standard. The FEM computed results on the strength safety of 70MPa hydrogen gas tank showed that the hydrogen fuel storage tank in which is fabricated by T800-24K and T700-12K of Toray, and MR60H-24P of Mitsubishi Ray is safe because those two carbon fibers have very similar material properties. But, the composite storage tank with a filling pressure of 70MPa in which is fabricated by T700-12K of Toray may not guaranty the strength safety, and thus this study recommends a composite hydrogen fuel tank under 60MPa.

• Steel and Composite Structures
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• v.51 no.3
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• pp.243-260
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• 2024

Thirteen self-compacting recycled concrete filled aluminium tubular (SCRCFAT) columns were tested under concentric compression loads. The effects of the replacement ratio of the recycled concrete aggregate (RCA) and steel fibre (SF) reinforcement on the structural performance of the SCRCFAT columns were studied. A control specimen (C000) was cast with normal concrete without SF to be reference for comparison. Twelve columns were cast using RCA, six columns were cast using concrete incorporating 2% SF while the rest of columns were cast without SF. Failure mode, ductility, ultimate load capacity, axial deformation, ultimate strains, stress-strain response, and stiffness of the SCRCFAT columns were studied. The results showed that, the peak load of tested SCRCFAT columns incorporating 5-100 % RCA without SF reduced by 2.33-11.28 % compared to that of C000. Conversely, the peak load of tested SCRCFAT columns incorporating 5-100% RCA in addition to 2% SF increased by 21.1-40.25%, compared to C000. Consequently, the ultimate axial deformation (Δ) of column C100 (RCA=100% and SF 0%) increased by about 118.9 % compared to C000. The addition of 2% SF to the concrete mix decreased the axial deformation of SCRCFAT columns compared to those cast with 0% SF. Moreover, the stiffness of the columns cast without SF decreased as the RCA % increased. In contrast, the columns stiffness cast with 2% SF increased by 26.28-89.7 % over that of C000. Finally, a theoretical model was proposed to predict the ultimate loads tested SCRCFAT columns and the obtained theoretical results agreed well with the experimental results.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.363-375
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• 2015

This research investigated the effects of diameter and material of energy frame on the impact velocity or strain rate of Strain Energy Frame Impact Machine (SEFIM). The impact speed of SEFIM have been clearly affected by changing the diameter and material of the energy frame. The reduced diameter of the energy frame clearly increased the impact velocity owing to the higher strain at the moment of coupler breakage. And, titanium alloy energy frame produced the fastest speed of impact among three materials including steel, aluminum and titanium alloys because titanium alloy has faster wave velocity than steel. But, aluminium energy frame was broken during impact tests. In addition, the tensile stress versus strain response of high performance fiber reinforced cementitious composites at higher and wider strain rates between 10 and 72 /sec was successfully obtained by using four different energy frames.

• Journal of the Mineralogical Society of Korea
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• v.21 no.3
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• pp.283-287
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• 2008

The imogolite synthesis wore performed by using tetraethoxysilane (TEOS) and aluminium-sec-butoxide (ASB) at < $100^{\circ}C$. A mixure of TEOS and ASB in a molar ratio of 1:2 was prepared under vigorous stirring and the experiments were performed under the hydrothemal refluxing condition. When the concentration of TEOS and ASB in solution was 0.5 M, a well-crystallized imogolite was synthesized, and the reflections wore shown at d = 22.4, $9.5\;\AA$ etc., after XRD analysis. DTA analysis shows 2 exothemal peaks at 68 and $249^{\circ}C$, suggesting the dehydration and the dehyroxylation reaction, respectively. The result of TG indicates 41% weight loss. And the weak and unsymmetrical peaks by the Si-O-Al stretching vibrations at 953 and $993cm^{-1}$ and by O-Si-O bending vibration at $562cm^{-1}$ were observed after IR analysis. The synthetic imogolite was fibrous and shows a spiders web like network structure.