• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.1
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• pp.45-53
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• 1985

For the analysis of vertical vibrations of a ship's hull, the Timoshenko beam analogy is accepted up to seven or eight-node modes provided that the system parameters are properly calculated. As to the shear coefficient, it has been a common practice to apply the strain energy method or the projected area method. The theoretical objection to the former is that it ignores lateral contraction due to Poisson's ratio, and the latter is of extreme simplifications. Recently, Cowper's and Stephen's shear coefficient formulas have drawn ship vibration analysts' attentions because these formulas, derivation of which are based on an integrations of the equations of three-dimensional elasticity, take Poisson's ratio into account. Providing computer programs for calculation of the shear coefficient of ship sections modeled as thin-walked multicell sections by each of the forementioned methods, the authors calculated natural vibration characteristics of a bulk carrier and of a container ship by the transfer matrix method using shear coefficients obtained by each of the methods, and discussed the results in comparision. The major conclusions resulted from this investigation are as follows: (1) The shear coefficients taking account of the effects of Poisson's ratio, Cowper's $K_c$ and Stephen's $K_s$, result in higher values of about 10% in maximum as compared with the shear coefficient $K_o$ based on the conventional strain energy methods; (a) $K_c/K_o{\cong}1.05\;and\;K_s/K_o{\cong}1.10$ for ships having single skin side-shell such as a bulk carrier. (b) $K_c/K_o{\cong}1.02\;and\;K_s/K_o{\cong}1.05$ for ships having longitudinally through bulkheads and/or double side-shells in the portion of the cargo hod such as a container carrier. (2) The distributions of the effective shear area along the ship's hull based on each of $K_o,\;K_c\;and\;K_s$ are similar each another except the both end portions. (3) Natural frequencies and mode shapes of the hull based on each of $K_c\;and\;K_s$ are of small differences as compared each other. (4) In cases of using $K_c\;or\;K_s$ in ship vibration analysis, it is also desirable to have the bending rigidity be corrected according to the effective breadth concept. And then, natural frequencies and mode shapes calculated with the bending rigidity corrected in the above and with each of $K_o,\;K_c\;and\;K_s$ result in small differences as compared each another. (5) Referring to those mentioned in the above (3) and (4) and to the full-scale experimental results reported by Asmussen et al.[17], and considering laboursome to prepare the computer input data, the following suggestions can safely be made; (a) Use of $K_o$ in ship vibration analysis is appropriate in practical senses. (b) Use of $K_c$ is appropriate even for detailed vibration analysis of a ship's hull. (6) The effective shear area based on the projected area method is acceptable for the two-node mode.

• Textile Coloration and Finishing
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• v.8 no.3
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• pp.52-58
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• 1996

In order to study an applicable level for the graft finish of silk filaments and the characteristics of silk fabric, some sample fabrics were woven with grafted weft and the characteristics of sample fabrics were analyzed to evaluate the mechanical properites and the handle values according to the graft yield(%) of MMA and HEMA monomers on silk filaments. 1. The tensile properties were detected in the increase of linearity(LT) and the recovery in time of the increasing resilience(RT). 2. The bending properties were detected to have a lot of effect on the balance of bending rigidity(B) to hysteresis(2HB) according to the elastic relaxation of warp tension and the interlacing stress. 3. The shearing properities were detected to show the softness and the elastics in a case of the decrease in shearing rigidity(G) and hysteresis(2HG, 2HG5) according to the graft yields. 4. The compression properties were detected in the decrease of linearity(LC) and the uniformity of resilience(RC). It explains that the tendancies of compressible variation is not accepted. 5. The surface properities were detected to be affected by the surface forms of grafted silk filaments and the variation in the morphologies of interlacing sections. Considering the interlacing eveness, MMA grafted fabrics were accepted within the level of WOMEN'S THIN DRESS(KN-201-LDY) but HEMA grafted fabrics were not accepted. 6. The variation of handles were detected in the increase of total hand(TAV) within the levels of 65% of KOSHI and 82% of HARI on the average. 7. The handle fashions were detected in the nature of Habuta and Dechine from MAA graft but the nature of Fugi were shaped from HEMA graft in proportion to the graft yields.

• Journal of Fashion Business
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• v.7 no.4
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• pp.121-128
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• 2003

A new textile material, poly(trimethylene terephthalate) polymer, has been introduced to the textile industry. The structure of PTT is similar to the PET, while the tensile deformation and subsequent recovery property is better than that of PET. In this study, the physical and mechanical properties of textile woven fabrics made of PTT, PET, and nylon 6 yarns as the filling yarn were determined using the Kawabata Evaluation System (KES), including tensile, bending, shearing, compression, and surface related parameters. On top of these measurements, the subjective ratings by evaluators were performed on the fabric samples. From the examination of the stress-strain behavior of the yarn specimens focused on the recovery mode, it was evident that the PTT specimen developed lower stress at 3% elongation. The subsequent recovery curve showed that the PTT has less stress-decay rate than the other specimens, implying that the recovery behavior of the PTT is recommendable for the end-uses including stretchable textile materials, sports wears, etc. The KES bending rigidity(B) value of the PTT sample fabric was lower than that of the PET sample fabric. Subjective evaluation of the fabric samples by the evaluators on the descriptive word pair "soft - not soft" showed similar tendency with the KES B determination of the fabric samples.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.64-76
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• 1999

In this paper hydroelastic experimental techniques of very large floating offshore structures are suggested based on the model test carried out in the UOU Ocean Engineering Wide Tank. The prototype is a box-shaped floating structure with length of 300m, breadth of 60m, depth of 2m and draft of 0.5m and longitudinal bending rigidity as $4.87{\times}10^{10}kgm^2$. The scale ratio is 1/42.857. The model is realized by aluminum square pipes with the section dimension of $20mm{\times}20mm$. The numbers of longitudinal and transverse pipes are 7 and 35 respectively. Heave motions at selected points are measured with potentiometers and bending moments with strain gages.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.8
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• pp.1153-1164
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• 2004

The purpose of this study was to knitted nine kinds of single knit and examined mechanical properties and hand to provide the fact that knit, tuck and miss stitch applied to various structure have an effect on hand of weft knitted fabrics. It was good to use tuck stitch rather than miss stitch to increase elasticity of knitted fabrics. As tuck stitch and miss stitch were double or triple overlaps, tensile resilence(RT) decreased by increase of friction contacted among stitch. As cross tuck stitch and cross miss stitch were knitted double or triple, bending rigidity(B), hysteresis of bending moment(2HB) and shearing(G) properties increased by jamming of stitch. As tuck stitch and miss stitch were overlap, thickness increased and they became thicker than miss stitch. Also, as they became thicker by these tuck stitch and miss stitch, compressional energy(WC) increased. It appeared that coefficient of friction(MIU) of cross tuck stitch was larger than coefficient of cross miss stitch. Mean deviation of surface roughness(SMD) had a tendency to be larger as tuck stitch and miss stitch increased. As cross tuck stitch and cross miss stitch were overlaps double or triple, KOSHI and FUKURAMI increased, total hand value(TIV) and NUMERI appeared high in double cross tuck stitch and double cross miss stitch.

• Fashion & Textile Research Journal
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• v.12 no.4
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• pp.494-499
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• 2010

Knitted fabrics are very popular for their numerous advantages such as greater comfort, attractive garment appearance, better fit on the body, etc. In this study, we investigated the mechanical properties and abrasion property of warp knitted fabrics for footwear which treated with several softeners to improve abrasion resistance. The antistatic softener among the various softeners showed high improvement in abrasion resistance. Among the mechanical properties with treating conditions, WT (tensile energy), G (shear stiffness), B (bending rigidity) increased as treating timeincreased. But the other mechanical properties were little changed with treating concentration.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.6
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• pp.609-609
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• 1998

This paper surveys the effect of rice straw ash solution to the physical properties of Sappan Wood dyeing fabrics. In the quantitative analysis of rice straw ash solution, the quantities of absorbed ingredients in fabrics were increased by bath pull treatment but the amount of absorption(K/S value) was increased by bath pH4.5 treatment. This is related to the metal ion. Among the metal ion, effect of Fe iou and Al ion were related. In case added extracted dye solution to mordants, the color dye solution became dark and increased reddish. The changes of mechanical properties of fabrics tensile resilience, bending rigidity(B), compressional resilience(RC) were increased. Generally mechanical properties were increased by rice straw ash solution treatment, specially bath pH9 treatment. Rice straw ash solution treatment of dyeing fabrics made the improvement in tensile strength and elongation and in the amount of absorption, dye ability, color fastness, mechanical properties, tensile strength, elongation.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.6
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• pp.699-705
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• 1998

This paper surveys the effect of rice straw ash solution to the physical properties of Sappan Wood dyeing fabrics. In the quantitative analysis of rice straw ash solution, the quantities of absorbed ingredients in fabrics were increased by bath pull treatment but the amount of absorption(K/S value) was increased by bath pH4.5 treatment. This is related to the metal ion. Among the metal ion, effect of Fe iou and Al ion were related. In case added extracted dye solution to mordants, the color dye solution became dark and increased reddish. The changes of mechanical properties of fabrics tensile resilience, bending rigidity(B), compressional resilience(RC) were increased. Generally mechanical properties were increased by rice straw ash solution treatment, specially bath pH9 treatment. Rice straw ash solution treatment of dyeing fabrics made the improvement in tensile strength and elongation and in the amount of absorption, dye ability, color fastness, mechanical properties, tensile strength, elongation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.11-18
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• 1991

Stiffened plate structure, which is generally used in the various structural design to develope the load carrying capacity, is classified in two groups; one is the plate stiffened with stiffeners, the other is corrugated plate. In the studies on those structures, the studies on the stiffened plates with stiffeners have been much studied with both quantities and qualities according to requirements of the minimum-weight structural design and the development in many industrial fields, especially automobile, ship and aerospace fields, but the studies on the corrugated plates are undeveloped in comparison with the stiffened plates, and also the analytical stiffness on the corrugated plates remains as the imperfect. In the present studies, the analytical method on the stiffness of corrugated plates made by folding is proposed, and the stiffness equation of corrugated plates with some angle is derived and generalized. The purpose of the present study is to contribute to the design of corrugated plates and to determine the optimum aspect ratio for parameters that decide the aspect of corrugated plates.

• Textile Coloration and Finishing
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• v.18 no.3 s.88
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• pp.49-58
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• 2006

The purpose of this study was to examine the effect of covering yarn's twist on mechanical properties of knitted fabrics of composite yarns with single covering process. Four yarns that were used in this study: two different composite yarns made from the four kinds of cotton and functional polyester-(Poly-A) with the ratio of 52:48, and the rest two yarns are the original cotton 100% yarn and the poly-A 100% yarn. The two kinds of composite yarns, CP1 and CP2, were processed on the single covering process. CP1 was applied on the single covering process with S-800 tpm, where Poly-A was used as covering yarn and cotton was used as core yarn. CP2 was applied on the same process as CP1 except that Poly-A had been applied on the two-for-one twisting process with S-400 tpm on the previous step. Sixteen mechanical properties of all the four knifed fabrics knitted under the same knitting conditions were measured by KES-FB system with the outer knit condition. And 3D CAD dressmaking simulations, which were driven by some of the mechanical properties, were presented. The results were as follows: CP2 had high RT values with twisting of covering yarn. CP2 also had high B, 2HB values because of higher linear density. SMD was affected rather by twisting of covering yarn than by fine hair of the cotton surface. Twisting of covering yarn made it decreasing T value and increasing W value. Dressmaking 3D CAD simulations showed that there are buckling effects on CP2 because of high bending rigidity and shear rigidity.