• 한국의류학회지
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• 제22권2호
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• pp.185-192
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• 1998

The methodology of applying fabric stretch ratio in the grants pattern drafting was evaluated. The experimental fabrics employed in this study were 3 different knit fabrics with various stretch ratio in vertical or horizontal direction. The firm fitting pants pattern was modified by applying the fabric stretch ratio in vertical ana horizontal direction. The computer automatic drafting method was used for pants pattenl alteration. The suitability of the altered pattern was evaluated by the 7 clothing specialists, The results showed that fit of all experimental garments was improved in general. The garment which was constructed with the fabric having large difference between horizontal stretch ratio and vertical stretch ratio showed poor fit at crotch area. This result implies that computer aided pattern alteration is not appropriate when fabric stretch ratio is vary by the fabric directions.

• 복식문화연구
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• 제9권3호
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• pp.433-446
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• 2001

Recently, according to changes in fashion trends, the importance of stretch fabric stands out. A lot of studies on non-stretch woven fabrics have been made, but few studies on stretch fabrics has been made yet. Especially, the study on ease for the patterns, according to body types, of stretch has not been made at all. The purpose of this study was to make clear reduction ratio due to the stretch ratio and to find out the ease for the patterns of stretch skirt according to standard body type to improve the aesthetics and wearing satisfaction. Therefore, fundamental data for aesthetic and functional patternmaking of the stretch skirt can be suggested. The results from the study were as follows: 1. The results from the appearance test were as follows. For the ease on waist, W+0㎝ and W-1㎝ for standard body type were suggested for the best fit. For the ease on hip, H+2㎝ and H+0㎝ for standard body type were suggested for the best wearing best fit. 2. The results from wearing satisfaction test were as follows. W+0㎝, H+2㎝ for standard body type were suggested for the best wearing satisfaction. 3. Based on the results from the above tests, the pattern reduction ratios for stretch skirt were as follows: pattern reduction ratio 3.0∼4.6% of waist, 2.1∼4.3% of hip for standard body type were suggested for the appropriate reduction ratio for stretch skirt. 4. The result from this study for stretch skirt was as follows: For standard body type, W+0㎝, W-1㎝ for waist and H+2㎝, H+0㎝ for hip were appropriate for stretch skirt pattern.

• 복식문화연구
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• 제9권4호
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• pp.652-663
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• 2001

The purpose of this study was to make clear reduction ratio due to the stretch ratio and to find out the ease for the patterns of stretch skirt according to the body types to improve the aesthetics and wearing satisfaction. Therefore, fundamental data for aesthetic and functional patternmaking of the stretch skirt can be suggested. The results from the study were as follows: 1. The results from the appearance test were as follows. For the ease on waist, W+0cm and W - lcm for thin body type were suggested for the best fit. For the ease on hip, H+0cm and H-2cm for thin body type were suggested for the best fit. 2. The results from wearing satisfaction test were as fDllows. W+Ocm, H+Ocm for thin body type were suggested for the best wearing satisfaction. 3. Based on the results from the above tests, the pattern reduction ratios for stretch skirt were as follows: pattern reduction ratio 3.3 ∼ 5.0% of waist, 4.8 ∼7.2% of hip for thin body type were suggested for the appropriate reduction ratio for stretch skirt. 4. The result from this study for stretch skirt was as follows: For thin body type, W+0cm, W - lcm for waist and H+0cm, H-2cm for hip were appropriate for stretch skirt pattern. Therefore, different ease has to be applied to stretch skirt pattern according to the body parts, to make the skirt looks good, is appropriate for thin body type, and is satisfied with appearance and wearing satisfaction test.

• 복식문화연구
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• 제10권4호
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• pp.392-403
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• 2002

The purpose of this study was to make clear reduction ratio due to the stretch ratio and to find out the ease for the patterns of stretch skirt according to fat body type to improve the aesthetics and wearing satisfaction. For this study, three college students were selected according to the fat body types; According to fat body types, 15 experimental skirt which were different each other in terms of the amount of ease on wait and hip, were made for the appearance test and wearing satisfaction test. The results from the study were as follows: 1. The results from the appearance test were as follows. For the ease on waist, W+2cm and W+0cm for fat body type were suggested for the best fit. For the ease on hip, H+2cm and H+0cm for fat body type were suggested for the best fit. 2. The results from wearing satisfaction test were as follows. W+2cm, H+2cm for fat body type were suggested for the best wearing satisfaction. 3. Based on the results from the above tests, the pattern reduction ratios for stretch skirt were as follows. pattern reduction ratio 0∼2.4% of waist, 1.9∼3.8% of hip for fat body type, were suggested for the appropriate reduction ratio for stretch skirt. 4. The result from this study for stretch skirt was as follows. For fat body type, W+2cm, W+0cm for waist and H+2cm, H+0cm for hip were appropriate for stretch skirt pattern. Therefore, different ease has to be applied to stretch skirt pattern according to the body parts, to make the skirt looks good, is appropriate for fat body type, and is satisfied with appearance and wearing satisfaction test.

• Elastomers and Composites
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• 제57권4호
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• pp.138-146
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• 2022

Research on the reduction of plastic use to prevent environmental pollution is urgently needed. Accordingly, studies on reducing the weight of polyethylene terephthalate (PET) bottles are currently being conducted. PET bottles are fabricated by injection stretch blow molding. In this study, stretch blow molding for fabricating PET bottles using preform studied through a computer simulation. Blowing characteristics are analyzed by varying the start time of the pre-blow, which is one of the process conditions of stretch blow molding. Simulation results and the preform inflation process are presented, and the parameters of stretch ratio, stretching path, thickness distribution, and weight distribution of blown PET bottles are investigated.

• 한국의류산업학회지
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• 제20권1호
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• pp.83-92
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• 2018

This paper investigated garment formability and fabric mechanical properties of one-way and two-way stretch fabrics according to the thermal treatment methods. One-way and two-way stretch fabrics were woven using 75d and 150d PET/spandex covering yarns and then these were wet thermal treated with four kinds of finishing machines. The fabric mechanical properties of these stretch fabrics specimens were measured and compared with the regular PET fabrics. The stretch ratio of one-way stretch fabric was ranged 12 to 26 percentage, 15 to 45 percentage for 2-way stretch fabrics and 4 to 10 percentage for regular fabrics. Garment formability of stretch fabric was superior than that of regular fabrics, in addition, 2-way stretch fabric was better than one-way. The garment formability of the stretch fabrics treated with CPB and Lava wet thermal machines showed the highest values, and the stretch ratio of these 2-way stretch fabrics was also the highest, which was ranged 20 to 45 percentage. This phenomenon was assumed to be due to high extensibility and bending rigidity with low shear modulus of the 2-way stretch fabric treated with CPB and Lava wet thermal machines. It was shown that the garment formability of stretch fabrics treated without dry thermal treatment was higher than that of dry thermal treated fabrics. It revealed that high stretch fabric was available under the condition of low process tension in the wet and dry thermal treatments of the finishing process, which makes high garment formability.

• Carbon letters
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• 제11권3호
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• pp.176-183
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• 2010

PAN precursor fibers were produced via wet-spinning process, and effects of polymerization and spinning processes, especially the stretching process, were investigated on mechanical properties and micro-morphologies of precursor fibers. An increase in molecular weight, dope solid and densification and a decrease in surface defects were possible by controlling polymerization temperature, the number of heating rollers for densification and the jet stretch ratio, which improved the mechanical properties of precursor fibers. The curves for strength, modulus, tensile power and diameter as a function of stretch ratio can be divided into three stages: steady change area, little change area and sudden change area. With the increase of stretch ratio, the fiber diameter became smaller, the degree of crystallization increased and the structure of precursor fibers became compact and homogeneous, which resulted in the increase of strength, modulus and tensile power of precursor fibers. Empirical relationship between fiber strength and stretch ratio was studied by using the sub-cluster statistical theory. It was successfully predicted when the strengths were 0.8 GPa and 1.0 GPa under a certain technical condition, the corresponding stretch ratio of the fiber were 11.16 and 12.83 respectively.

• 소성∙가공
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• 제7권1호
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• pp.36-48
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• 1998

In order to analyze the stretch flange forming characteristics of tailored blanks. laser welded blanks of different thickness and strength combinations were prepared and hole expansion tests were done. The stretch flange formability of laser welded blanks was reduced as increasing the deformation restraining force($strength{\times}thickness$) ratio between two welded sheets. Simulation of stretch forming mode deformation and comparson with experimental results showed that the stretch flange formabili-ty was influenced not only by the difference of the deformation restraining forces between two base sheets but also by the difference of the deformation restraining forces between base sheet and weld. Therefore the stretch flange formability was reduced more rapidly than tensile elongation as increas-ing the deformation restraining force ration. It was also found that simulation of stretch flange forming was more accurate when material properties of weld was given.

• 한국해양공학회지
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• 제32권4호
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• pp.253-260
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• 2018

Recently, the application of non-steel materials in ships and offshore plants is increasing because of the development of various nonlinear materials and the improvement of performance. Especially, hyper-elastic materials, which have a nonlinear stress-strain relationship, are used mainly in marine plant structures or ships where impact relaxation, vibration suppression, and elasticity are required, while elasticity must be maintained, even under high strain conditions. In order to simulate and evaluate the behavior of the hyperelastic material, it is very important to select an appropriate material model according to the strain of the material. This study focused on the selection of material models for hyperelastic materials, such as rubber used in the marine and offshore fields. Tension and compression tests and finite element simulations were conducted to compare the accuracy of the nonlinear material models due to variations in the stretch ratio of hyper-elastic material. Material coefficients of nonlinear material models are determined based on the curve fitting of experimental data. The results of this study can be used to improve the reliability of nonlinear material models according to stretch ratio variation.

• Elastomers and Composites
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• 제38권4호
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• pp.354-362
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• 2003

The use of a petaloid design for the bottom of carbonated poly(ethylene terephthalate)(PET) bottles is widely spread. This study investigated the causes of bottom cracks. The tensile yield stress variations of PET according to the crystallinity and stretch ratio were examined, then the stretch ratio and strength in the bottom area of a blown bottle were analyzed. A crack test was also performed to observe the cracking phenomena. The distribution of the effective stress and maximum principal stress were both examined using computer simulation to seek the influence of the bottom design on crack. It was concluded that the bottom cracks occurred because of inadequate material strength due to the insufficient stretching of PET, plus the coarse design of a petaloid bottom. The stretch ratio at the bottom during bottle blowing should be higher than the strain hardening point of PET to produce enhanced mechanical strength. The cracks in the bottom of the PET bottles occurred through crazing below the yield stress. The maximum principal stress was higher in the valleys of the petaloid bottom than in the rest bottom area, and the maximum principal stress had a strong effect on the cracks.