• Journal of the Korean Society of Clothing and Textiles
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• v.4 no.1_2
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• pp.25-33
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• 1980

The studies on shrinkage and characteristics of the weft knitted fabrics were investigated under the various dry and wet treating conditions. Various relaxation values were found out according to treating conditions. The characteristics of knitted fabrics such as shrinkage rate, thickness, spirality, elongation and recovery were also measured. The used knitting yams were OE (open-end) cotton and POY (pre-oriented yarn)-DTY (draw textured yam) polyester. The conclusions obtained in this study are as follows. 1. In case of dry relaxation little change of Ks values was seen with increasing time after 48 hours. So it was found that relaxation shrinkage of dry relaxation reached its maximal state in about 48 hours. 2. In case of wet relaxation, higher Ks values were observed, in comparision with those of dry one and higher shrinkage rates were also observed. But when experimental temperature was constant, sudden marked increases in Ks values and shrinkage rates appeared through the initial 4 hours, and after that time little change was seen in them. 3. As Ks value increases, thickness also increased. But thickness showed to some degree stability around Ks value 23. 4. As Ks value increases, spirality values also increased gradually. But little change of spirality values was observed above a certain Ks values (cotton 22.5, polyester 21.5). 5. As Ks value increases, the elongation decreased under a certain load, and the recovery was random.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.1
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• pp.170-181
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• 1997

The purpose of this study was to determine the effect of knit structure and knit density (machine tightness factor) on the dimensional properties and K1-4 values of weft-knitted fabrics followed over eleven cycles of mechanical relaxation to provide the basic data for constructing weft-knitted fabrics for outwear with excellent dimensional stability The eighteenth weft-knitted fabrics were produced with different knit structure (1$\times$1 rib, half-cardigan rib, half-milano rib, interlock, single pique, crossmiss interlock) and machine tightness factor (loose, medium, tight) for this study. Dimensional properties such as width, lengh, area shrinkage and dimensional parameter (K) of eighteenth knitted fabrics including thickness and bulk property were measured. The results were as follows; 1. The dimensional behavior of the Ix1 rib and interlock in relaxation cycles was anisotropic, i.e., length shrinkage was usually associated with a width expansion, whereas the other weft-kntted fabrics which have tuck or miss loops in the knit structure behaved isotropically, i.e., length and width shrinkages were usually found. It was proposed that the difference in dimensional behavior between these structures was due to the dissimilar nonrelaxed geometrical shapes of the individual structural units forming these weft-knitted structures. The mechanical relaxation shrinkage of weft-knitted cotton fabrics was dependent on the tightness of construction. For a range of fabrics knitted on this study, an increase in fabric tightness caused a decrease in the length shrinkage of the fabric accompanied by an increase in its width shrinkage.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.9_10 s.146
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• pp.1274-1284
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• 2005

Effect of fixation methods and relaxation treatment on the dimensional stability and physical properties of MDPPA/HMM treated cotton knitted fabrics were studied. Combination of four different fixation methods - relaxation, swelling agent treatment, pad dry cure fixation, and wet fixation - were applied to flame retardant finish of 4 kinds of cotton knitted fabric with MDPPA/HMM. Then these fabrics were washed 10 times. As a result, In swelling treatment on 10G showed relatively higher value of length shrinkage than 14G. Length and width shrinkage were increased by initial washing treatment and no further change was shown after 6 washing cycles. After 10 washing cycles, length and width shrinkage decreased. The KES standardized basic value of B/W, 2HB/W and bursting strength of interlock were relatively larger than those of single jersey. The values of B/W and 2HB/W of cotton knitted fabrics were increased by relaxation and washing treatment but were decreased by swelling treatment. In addition, the bursting strength of the cotton knitted fabrics was decreased after fusing, washing and relaxation treatment.

• Journal of the Korean Society of Industry Convergence
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• v.16 no.2
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• pp.47-52
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• 2013

Aim of this study is to investigate the dimensional and shrinkage characteristics of the weft knitted fabrics with Polylactic acid(PLA) knitted yarn. This PLA knitted yarn was made of the biodegradability fiber. The structure of weft knitted fabrics that was utilized for this study is the plain stitch, which is the most basic structure among all weft knitted fabrics. As the stitch length is shorter, the stitch density, courses density, and wales density are more increasing. The stitch density increased as pre-treatment process and dyeing process progressed. On the contrary, the heat setting process made it decreasing. The MR(Machine Relaxation) and DR(Dry Relaxation) standard area shrinkage were increasing as wet process progressed and as the stitch lengths are long.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.496-499
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• 2006

In this study, a practical method of shrinkage stress analysis on concrete slab in multi-story building is proposed, which considers both internal restraint and external restraint variation resulting from construction sequence. The shrinkage stress due to external restraint is obtained by multiplying relaxation coefficient to elastic shrinkage stress. The additional shrinkage stress due to internal restraint is obtained by residual strain of the elastic analysis. A verification example was analyzed and compared by the proposed method and commercial analysis program that is capable of time-dependent analysis of concrete. The results of 10-story example building show that the internal restraint of reinforcement increases the shrinkage stress considerably at the slabs under loose external restraint.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.729-737
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• 2013

The environmental load of concrete pavement can be categorized by temperature and moisture loads, which mean temperature distribution, and drying shrinkage and creep in the concrete slab. In this study, a method calculating the environmental load essential to mechanistic design of airport concrete pavement was developed. First, target area and design slab thickness were determined. And, the concrete temperature distribution with slab depth was predicted by a pavement temperature prediction program to calculate equivalent linear temperature difference. The concrete drying shrinkage was predicted by improving an existing model to calculate differential shrinkage equivalent linear temperature difference considering regional relative humidity. In addition, the stress relaxation was considered in the drying shrinkage. Eventually, the equivalent linear temperature difference due to temperature and the differential shrinkage equivalent linear temperature difference due to moisture were combined into the total equivalent linear temperature difference as terminal environmental load. The environmental load of eight civilian and two military airports which represent domestic regional weather conditions were calculated and compared by the method developed in this study to show its application.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.123-130
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• 2019

As a cold-weather-concrete construction technique for enhancing the sustainability and improving efficiency of cold-weather construction, the cracking timing, the starting point of deterioration for concrete, due to the shrinkage of the blast furnace slag cement concrete including accelerator was evaluated. As a result, by using blast furnace slag and accelerator, the cracking was developed faster with higher cracking potential under the restrained conditions at constant age and free-shrinkage strain. It can be considered that the results of decreased stress relaxation by creep or increased restraint with increased free-shrinkage strain causes the increased cracking development speed. Hence, it should be considered the necessary of cracking due to the shrinkage when blast furnace slag or accelerator was used for cold-weather construction.

• Structural Engineering and Mechanics
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• v.5 no.3
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• pp.307-327
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• 1997

This paper is concerned with the time dependent service load behaviour of prestressed composite tee beams. The effects of creep and shrinkage of the concrete slab are modelled using the age adjusted effective modulus method and a relaxation approach. The tendon strain is determined considering compatibility of deformations and equilibrium of forces between the tendon and the composite tee beam. A parametric study is undertaken to study the influence of various aspects on the stress, strain and deformations of the concrete slab, steel beam and prestressing tendon. The effect of loading type and tendon relaxation has also been considered for various types of prestressing tendon materials. Recommendations are then made in relation to adequate span to depth ratios for varying levels of prestressing force.

• Fashion & Textile Research Journal
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• v.8 no.5
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• pp.591-596
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• 2006

In order to analyze the tailorbility of different fabrics for men's suit, FAST system has been used for measuring the distribution of mechanical properties in this study. As results, cashmere mixed woolen fabrics showed the minimum degree in relaxation shrinkage, formability, and shear rigidity than any other fabrics, and also showed more than 6% as maximum level of extensibility. Thus, cashmere mixed woolen fabrics requires careful tailoring in lay-out, marking, and cutting. It is necessary to establish new tailoring criteria for automatic sewing with cashmere mixed woolen fabrics than any other fabrics, because they show more failure rate of tailorbility. There have been noticeably more variation of shrinkage and extension for woolen fabrics with cashmere mixed than 100% woolen fabrics by evaluating the formability of the suits when these are completed to suits through cutting and tailoring from fabrics. Especially nylon mixed woolen fabrics showed shrinkage overall, but polyester mixed woolen fabrics showed extension at waist area. Thus, it is necessary to adjust the appropriate overfeed rate considering the amount of shrinkage and extension while tailoring.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.726-733
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• 2002

Shrinkage strip or separation strip is a temporary joint that is left open for a certain time during construction to allow a significant part of the shrinkage to take place without inducing stress. A shrinkage stress analysis method of shrinkage strip in concrete slab of multi-story building considering the relaxation effect of creep and construction sequence is proposed. The analysis results of 10-story example building show that the effect of shrinkage strip can be analyzed easily by the proposed method. And shrinkage strip installed in a particular floor makes the stress of that floor reduced and the stress of the other floors increased a little. The rate and amount of stress reduced with closing time mainly depends on the development of shrinkage with time of concrete model used. The amount of stress reduced is determined by the amount of shrinkage strain developed before the closing of shrinkage strip.