• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.405-413
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• 1997

In the present paper, it is attempted to reconfirm the "Intelligent" material properties using both the sintered TiNi/Al(1100) matrix composite made by powder metallurgy method and the squeeze-casted TiNi/Al6061 specimens. A metal matrix composite is, its fault has been considered to deteriorate a strength of composite by heating residual stress of the matrix. Therefore, it is necessary to remove a tensile residual stress, to produce the strength of a composite better. On the contrary, if compressive residual stress happens in matrix of composite in place of tensile residual stress, it will make the strength of composite better. So that, this paper introduce the development of a high strength of composite, by using compressive residual stress well, on the study. By using these specimens, shape memory strengthening effects in tensile strength and fatigue crack propagation above inverse transformation temperature of TiNi fiber were investigated. We occurs the prestrain and volume fraction for to discuss the effects of a composite strength. Moreover, by SEM observation, the effect of the residual stress at the interface between Al matrix and TiNi fiber and some brittle precipitation layers such as inter metallic compounds on fracture mechanisms was discussed metallurgically.urgically.

• Membrane Journal
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• v.17 no.2
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• pp.134-139
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• 2007

Experimental and numerical analysis were performed for separation of carbon dioxide from carbon dioxide and nitrogen gas mixture using a polyethersulfone hollow fiber membrane. The experimental results were compared with those obtained at the same operating condition by the numerical analysis. It was observed that there was a big difference between the experimental results and those by a numerical analysis where the permeance of carbon dioxide and its ideal selectivity over nitrogen were obtained from the pure gas permeation. Therefore, the permeance of carbon dioxide and its selectivity were obtained from the separation experimental results using the numerical analysis as a function of the mole fraction of carbon dioxide, the feed pressure and the permeate pressure in the gas mixture. The results of the numerical analysis using the selectivity obtained from the gas mixture were in good agreement with those of the experimental.

• Composites Research
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• v.23 no.2
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• pp.10-16
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• 2010

$Al_2O_3$ fiber and SiC particle hybrid metal matrix composites (MMCs) were manufactured by squeeze casting method investigated for their tribological properties. The pin specimens had different ratios of fiber to particle content but their total weight fraction was constant at 20 wt. %. Tribological tests were performed with a pin-on-disk friction and wear tester. The investigation of the dry tribological characteristics of hybrid MMCs were carried out at room temperature and elevated temperature of$100^{\circ}C$ and$150^{\circ}C$. The morphologies of worn surfaces were examined by scanning electron microscope (SEM) to observe tribological characteristics and investigate wear behavior. The results revealed that the wear resistance improved with the content of SiCp increased of the planar random (PR) MMCs at room temperature. At the elevated temperature, it revealed that the wear resistance of normal (N) MMCs was superior to that of the PR-MMCs due to PR-fibers were easily pulled out holistically from the worn surface. Meanwhile, the coefficient of friction decreased with the temperature increasing.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.2
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• pp.104-113
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• 2020

The study aims to improve the previous theory-based algorithm on the lightweight design of laminate structures of a composite ship based on the mechanical properties of fiber, resin, and laminates obtained from experiments. From a case study on using a hydrometer to measure the specific gravity of e-glass fiber woven roving fabric/polyester resin used as the raw material for the hull of a 52 ft composite ship, the equation for calculating the weight of laminate was redefined, and the relationship between decreasing mechanical properties and increasing glass content was determined from the results of material testing according to ASTM D5083 and ASTM D790. After applying these experimental data to the existing algorithm and improving it, a possible laminate design that maximizes the specific strength of the composite material was confirmed. In a case study that applied the existing algorithm based on rules, the optimal lightweight design of composite structures was achieved when the weight fraction of e-glass fiber was increased by 57.5% compared with that in the original design, but the improved algorithm allowed for an increase of only 17.5%.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1113-1120
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• 2000

Productivity, nutrient contents, in vitro gas production and in sacco degradability of different fractions and whole OPF were determined to assess the feeding value of OPF as a ruminant feed. An in vivo digestibility trial was also carried out using goat. Freshly harvested OPF was randomly collected, partitioned and weighed. An OPF from 21 years older palm weighed 13.4 kg and the annual fresh matter yield of petiole, leaflet and midrib was 46.5, 11.8 and 3.4 ton/ha, respectively. Leaflet contained 439, 926, 698, 501, 168, 196, 748 and 52 (g/kg) of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CE), hemicellulose (HC), total carbohydrate (TC) and non fiber carbohydrate (NFC), respectively. Petiole contained lower (p<0.01) DM, CP and EE contents than leaflet. Organic matter, CE and TC contents were higher (p<0.01) in petiole compared to leaflet. Silica and lignin contents were highest (p<0.01) in midrib followed by leaflet, whole OPF and least in petiole. The Ca, P, Na, K and Mg contents (g/100 g DM) of leaflet were 0.529, 0.182, 0.039, 0.876, and 0.168, respectively. In vitro DM digestibility (g/100 g) at 48 h of leaflet, petiole and midrib was 32.7, 38.7 and 30.2, respectively. The in sacco DM degradation (g/100 g) at 48 h of leaflet was higher than that of whole OPF, petiole and midrib. The in vivo digestibility of DM, OM, CP and ADF of whole OPF was 52, 56, 43 and 26%, respectively. It can be concluded that leaflet is the most nutritious fraction of OPF and midrib is the least. The nutrient content and digestibility of the whole OPF showed that OPF could be an alternative roughage source for ruminant diets.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.906-912
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• 2000

The effect of ammonia treatment and rice bran supplementation on the in situ rumen degradation of rice straw was determined using three Japanese Corriedale wethers fitted with permanent rumen cannula. About 4 g samples of diets containing 100% untreated rice straw (URS); 100% ammonia treated rice straw (ARS); 65% URS+30% rice bran (RB)+5% soybean meal (SBM) (T1); and 85% ARS+15% RB (T2) were incubated at 0, 4, 8, 16, 24, 48, 72, and 96 hours in the rumen of sheep to measure dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) degradability. The DM disappearance of ARS based diets were about 20% higher than that of URS based diets. Rice bran supplementation improved DM disappearance of URS but not on ammoniated straw. Degradation parameters showed that ammoniation increased rate (c) of straw degradation resulting to higher DM and fiber degradability but RB supplementation did not. ARS gave similar DM and CP solubility and effective rumen degradability (ED) with that of the supplemented groups indicating that ammoniation alone can give the same effect on rumen degradability of sheep receiving low quality roughage. All degradation parameters for NDF were consistently higher in ARS based-diets indicating improved fiber solubility. Rice bran supplementation did not affect degradation characteristics of the diets except on soluble DM and CP fraction (A) of URS but not on ARS.

• Composites Research
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• v.17 no.5
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• pp.1-6
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• 2004

Composite pressure vessels with HDPE (high density polyethlyne) liner with metal boss at each end were developed by Filament Winding Process. The vessel is composed of a dome-shaped part at each end and a cylinder-shaped part at the middle of the vessel. The environmental tests carried out for possible vessel materials such as High Density Polyethlyn (HDPE), resins and reinforcing fibers up to a year showed no significant damages. The boss was designed to minimize the gas leak which was verified by FEM analysis. Most ideal fiber tension was obtained by experimental method and the fiber volume fraction, $\textrm{V}_{f}$, obtained by image analyzer were 55.4 % in cylinder and 55.6 % in dome parts, respectively. Winding pattern is programmed to control the composite thickness in the dome areas such that the failure of the vessel may occur in the cylinder. During the cure, the vessel was rotated and a constant internal pressure of 0.62 bar was applied. From this, the vessel's burst pressure is improved by 28 %. The burst and fatigue tests for under-wound and fully wound vessel showed satisfactory results.

• Composites Research
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• v.33 no.3
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• pp.169-175
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• 2020

The compression and tension test were performed to evaluate the stiffnesses of the conical composite lattice structures and results of test were compared with finite element analysis results. Because of difficulty to perform simple tension and compression test due to conical shape, suitable specimens and jig for test were made. Subelements extracted from the structure were prepared for compression test. Compression test of subelement was performed and compressive strains in fiber direction were measured. Compressive stiffness of the helical rib was verified by finite element analysis results. For stiffness of hoop rib, hoop ring specimens were extracted from the structure. Tension test of hoop ring specimen was performed to apply bending deformation to hoop rib. Stiffness of hoop rib was verified by finite element model considering various fiber volume fraction in thickness direction.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.925-928
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• 2008

Fiber is an important ingredient in strain-hardening cementitious composite (SHCC), which can control fracture of cementitious composite by bridging action. The properties of reinforcing fiber, as tensile strength, aspect ratio and elastic modulus, have great effect on the fracture behavior of SHCC. To apply SHCC to structural member, SHCC must have economical efficiency and workability as well as own excellent tensile performance. For these purposes, four-point bending and direct tensile tests on SHCC with only hybrid synthetic fibers, total fiber volume fraction, $V_f$, is 1.5%, are carried out. The research emphasis is on the mechanical properties of SHCC made in Polyvinyl alcohol (PVA) and Polyethylene (PE) fibers, and how this affects the composite property, and ultimately its strain-hardening performance. Also, effect of hybrid type and water-cement ratio on the behavior of SHCC was evaluated in this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.913-916
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• 2008

Direct tensile response of strain hardening cement composites(SHCC) depends primarily on the material's tensile response, which is a water cement ratio, direct function of fiber and matrix characteristics, the bond between them, and the fiber volume fraction. This paper discusses effect of aspect ratio of the direct tensile response of SHCC with PET and PVA fibers. The main variables considered include the aspect ratio of PET fibers(Aspect ratio, ${\ell}/d_f$ : 150, 300, 600). For the same mixture proportion, PET1.5+PVA0.5-300 and PET1.5+PVA 0.5-600(Aspect ratio 300, 600) showed better overall behavior(Pseudo strain-hardening, Multiple cracking) than specimens with PET1.5+PVA0.5-150(Aspect ratio 150). Tensile strain of PET1.5+PVA0.5-300 and PET1.5+PVA 0.5-600 at ultimate tensile stress were 0.5, 2.0% respectively.