• Textile Coloration and Finishing
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• v.13 no.6
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• pp.70-70
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• 2001

This study surveys the fiber behavior in yarn formation and the Physical properties of Solo-spun yarn. The specimens were made by six types of Solo-spun rollers with fixed twist multiplier In the previous part, the physical properties such as yarn count, evenness, strength, and breaking elongation of these yarns were compared with the properties of ring spun yarns and analysed with the mechanism of Solo-spun yarn formation. In the second part of this report, the abrasion resistance and hairiness were discussed with respect to the micro yarn structures. The narrower the groove width of Solo-spun roller is, the more active the bulk fiber migration is. The Solo-spun yarn structure has two groups. One is shorter than the other one in longitudinal direction of yarn and has the same structure as ring-spun yarn, which is derived from the smooth zone on the surface of Solo-spun roller. The other one is longer than the former and there are the wrapping fibers. This part is derived from the conflicted grooves on the surface of Solo-spun roller.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.68-74
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• 2006

2024 Al alloys were severely deformed by equal channel angular pressing(ECAP) to obtain an ultrafine grain structure. The more deformation amount increased, the more grain size decreased. Most of the grain structure were changed from elongated to equiaxed shape with increasing pass number. The morphology of S' phases was also changed from rod-type to spherical type. The grain size of 6 passed specimen was 100 to 200 nm, and the size of S' phases was about 10 nm in the microstructure. XRD measurements have revealed that the texture formed by plastic deformation disappeared in the 6 passed specimen. SP test results described that the start of crack propagation occurred at the transition zone between plastic bending and membrane stretching because of small elongation. The maximum strength of ECA pressed specimen increased 1.9 GPa to 2.9 GPa with increasing pass number.

• Journal of Korean Association for Spatial Structures
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• v.12 no.4
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• pp.57-69
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• 2012

This study investigated the behaviors of the gabled hyperbolic paraboloid shell structure subjected to differential settlement and the horizontal displacement due to the elongation of tie rod/beam on supports. Two types of shell structure with different roof slopes are used in study; conventional type which has perimeter beams around the shell panel, and simple type which removes the edge beams along the slab edge line. The effect of the removal of edge beam under vertical or horizontal displacement on supports, and the roof slope was compared using the finite element analysis.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1045-1047
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• 2006

Fabrication of $Mg_{95.75}Zn_1Y_3Yb_{0.25}$ bulk alloy has been performed through the consolidation of rapidly solidified ribbons. The $Mg_{95.75}Zn_1Y_3Yb_{0.25}$ bulk alloy exhibited excellent mechanical properties, high tensile yield strength of 530 MPa, and large elongation of 3 %. Microstructure of the alloy was characterized by equiaxed fine grains that consist of -Mg, long period ordered (LPO) structure phase, and $Mg_5RE$-type cubic compound. The strengthening of the alloys may be due to fine grains with LPO structure phase and $Mg_5RE$-type compound.

• Macromolecular Research
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• v.10 no.6
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• pp.297-303
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• 2002

We have investigated the microstructural properties of a weakly charged polyelectrolyte modeled with both Hookean spring and Debye-Huckel potential, by employing a novel hybrid scheme of molecular dynamics (MD) and Monte Carlo (MC) simulations. Although the off-lattice pivot step facilitates the earlier computations stage, it gives rise to oscillations and hinders the stable equilibrium state. In order to overcome this problem, we adopt the MC off-lattice pivot step in early stage only, and then switch the computation to a pure MD step. The result shows that the computational speed-up compared to the previous method is entirely above 10 to 50, without loss of the accuracy. We examined the conformations of polyelectrolyte in solvents in terms of the end-to-end distance, radius of gyration, and structure factor with variations of the screening effects of solvent and the monomer charges. The emphasis can favorably be given on the elongation behavior of a polyelectrolyte chain, with observing the simultaneous snapshots.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1541-1558
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• 2023

The new Modified-690Gd alloy, namely as Ni-30Cr-(10-x) Fe-xGd (x = 0.5, 1.0, 1.5,2.0, 3.0 wt%) for function structure integrated thermal neutron shielding has been prepared and characterized. The Modified-690Gd alloy was mainly composed of γ austenite matrix and (Ni, Cr, Fe)₅Gd precipitated along grain boundaries. The new Modified-690Gd alloy had great mechanical properties, which had the tensile strength exceeding 620 MPa and the elongation being above 50%. Meanwhile, this alloy had excellent weldability and good corrosion resistance in boric acid. The new Modified-690Gd alloy is expected to be a kind of high efficiency thermal neutron shielding materials.

• Journal of Life Science
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• v.14 no.3
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• pp.396-399
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• 2004

This study was investigated the changes of root length, tissue structure of root tip, and dry matter production of a Dongjinbyeo (DJ) cultivar subjected to 0.4 % agar medium with various concentration of NaCl (salt stress)- and polyethylene glycol 6000 (PEG, drought stress). Root length and dry weight of DJ plant were declined along the high concentration of PEG and NaCl in rice plants. To elucidate the changes of tissue structure in root tip to PEG- and NaCl-treatments, we examined the microscopic observation of root tip in NaCl- and PEG-treated rice plants using Toluidine blue O. By Toluidine blue O staining, methyl-lignin accumulation was found in the epidermis and outer cortex of the elongation zone at an early stage of PEG treatment, whereas was found only the outer cortex of the elongation zone of NaCl-treated root tip. The epidermis of NaCl-treated root tip became soften instead of methyl-lignin accumulation. TR ratio was increased along the high concentration in PEG- and NaCl-treated rice plant as a result of inhibited root elongation under PEG- and NaCl-treatment. From these morphological changes in root stimulated by drought and salt stress, we suggest that agar medium is useful to identify tolerant variety in germination stage under stressful environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.4
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• pp.237-242
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• 2008

The tunic of Styela clava(SCT) consists of a proteoglycan network. Regenerated cellulose films were prepared by solution casting and coagulation of SCT in N-methylmorpholine-N-oxide(NMMO)/$H_2O$(87/13 wt%). The crystalline structure of powdered SCT was primarily that of cellulose I. The crystalline structure of SCT films exhibited a cellulose II structure, similar to that of viscose rayon. Physical characterization of SCT films and fibers revealed an intrinsic viscosity($\eta$) of 6.35 dL/g, average molecular weight($M_w$) of 423,000 g/M, and fiber density of 1.50 $g/cm^3$ with a moisture regain and water absorption of 10.20% and 365%, respectively. The results were similar to those of cellulose films regenerated from wood pulp. Films prepared with 6 wt% SCT exhibited strong tensile strength, high water absorption, and a greater degree of elongation. Scanning electron micrographs(SEM) of film cross-sections showed a layered, sponge-like structure.

• Fashion & Textile Research Journal
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• v.14 no.4
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• pp.635-640
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• 2012

In this study, thermoplastic urethane (TPU) coating yarns were prepared at various extruding temperatures. The fine structure and mechanical properties of resultant TPU coating yarns examined by the wide angle X-ray diffractometer (WAXD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile test. TPU coating yarns (prepared at extruding temperatures at $175^{\circ}C$) were confirmed as a stable fine structure that obtained excellent tensile strength and flexibility. The C samples prepared by optimized conditions made by TPU woven floor mat. The structure of the woven mat is $4{\times}4$ basket weave and have laminated with the EVA foam to obtained final TPU woven floor mat products. The resultant TPU woven floor mat was obtained to 1.5MN of tensile strength, 22% of the elongation, and 0.2MN of tear strength. The weight loss abrasion and the resilience by the ball rebound of the TPU-woven floor mat was prior to those of the PVC subsequently, we were able to develop a woven floor mat with TPU coating yarn and produce an eco-friendly high valuable woven floor mat using an interior product.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.221-228
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• 2012

An active compensation method for the deformation of composite structures using additional controllable metal parts is proposed, and its feasibility is experimentally investigated in a simulated space environment. Composite specimens are tested in a vacuum chamber, which is able to maintain pressure on the order of 10-3 torr and interior temperature in the range of ${\pm}30^{\circ}C$. The displacement-measuring interferometer system, which consists of a heterodyne HeNe laser and an interferometer, is used to measure the displacement of the whole structure. Meanwhile, the strain of the composite part and temperature of both parts are measured by fiber Bragg grating sensors and thermistors, respectively. The displacement of the composite structure is maintained within a tolerance of ${\pm}1{\mu}m$ by controlling the elongation of the metal part, which is bonded to the end of the composite part. Also, the possibility of fiber Bragg grating sensors as control input sensors is successfully demonstrated using a proper corrective factor based on the specimen temperature gradient data.