• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.29-32
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• 2002

In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non- coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

• Journal of the Korean Society of Costume
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• v.58 no.1
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• pp.1-8
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• 2008

The purpose of this study was to investigate the mechanical properties and hand values of polypropylene knit and to analyze its color-fastness for light, laundering and abrasion, comparing to nylon and polyester knits. The results of this study were as follows: 1. Polypropylene stretched more with less force than nylon and polyester and its elastic recovery and shape stability were better than nylon and polyester. 2. Polypropylene was more flexible than nylon and polyester. 3. Polypropylene stretched more easily for shearing but its recovery from shearing was less than nylon and polyester. 4. Polyester had smoother surface than nylon and polyester. 5. Polypropylene was compressed more easily than polyester with less force but less than nylon. Its recovery from compression was more than nylon and polyester. 6. Polypropylene had lower KOSHI and SHARI values and higher FUKURAMI value than nylon and polyester. It had better T.H.V. value than nylon but less than! polyester. 7. Color fastness of polypropylene for lanudering, light, and abrasion in wet and dry conditions was good except polypropylene dyed with red color.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.75-79
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• 1995

A cutting experiment using diamond tool was performed to make the die cabity which is composed of micro groove with mirror surface. Fine cutting depth was generated by the elastic recovery of the modified tool holder on the conventional M/C. Surface roughness and profile were investigated with cutting speed and depth and through the low cutting speed of 10mm/min, Rmax 0.005 .mu. m or less of machined surface could be achieved.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.53-56
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• 1997

The multistage precision forming process for aperture of electronic guns consists mainly of drawing and swaging operations. The multistage forming sequence is analyzed in view of production industry, and based on the industrial investigation. The processes are simulated by the finite element code MARC. The elastic recovery, strain and stress distribution, and the die forces are summarized.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.5
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• pp.551-564
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• 2003

Statement of problem : Magnesium oxide may increase pH of alginate, and supply magnesium ions to the polymerization reaction of alginate. Purpose : This study was designed to evaluate the influence of incorporation of magnesium oxide to alginate composition. Material and Method : Seven kinds of experimental alginates were prepared and used for the experiments. Components with unchanging concentrations were sodium alginate 15%, calcium sulfate 14%, sodium phosphate 2%, and zinc fluoride 3%. Contents of magnesium oxide were varied as 0%, 1%, 2%, 3%, 4%, 5%, 6%. Diatomaceous earth were added to each experimental groups as balance to be 100%. Control group was a MgO 0% group. Working time, setting time, elastic recovery strain in compression, compressive strength and tear resistance were measured were measured. Sample size for each groups were 10. Arithmetic means were used as each groups representative values. Regression test between MgO contents and results, Duncan's multiple range test, and One-way ANOVA test were done between groups at level of 0.05. Results : 1 Magnesium oxide made the working time and setting time as longer(p<0.0001). 2 Magnesium oxide did not alter the elastic recovery(p>0.05). 3. Magnesium oxide contents between 2% and 4% exhibited the lowest strain in compression on alginates(p<0.0001). 4. Magnesium oxide made the compressive strength and the tear resistance stronger(p<0.0001). Conclusion : These results mean that setting time of alginate maybe controlled and that mechanical properties maybe improved by the incorporation of magnesium oxide into alginate, without any reduction of elasticity.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.5
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• pp.701-710
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• 2009

This study was conducted to develop excellent insole with good thermal insulation using new materials. We investigated that aerogel/fiber composite can be used as padding materials of shoes by comparing surface shape, moisture regain, water vapor permeability, thermal insulation and compression rate of insole materials tried with nonwoven fabric padding materials and insole sold in market. The results are as follows. Surface shapes were shown that the most appropriate material for sealing aerogel/fiber composite was high density fabric as per size of particle of aerogel. Moisture regain of aerogel/fabric composite was better than nonwoven fabric padding samples. However, when compared to insole sold in market, its moisture regain was worse than those of insole merchandises. Water vapor permeability was higher in material padded with nonwoven fabric than materials padded with aerogel/fiber composite in all three kinds of sealing fabrics. Thermal conductivity of aerogel/fabric composite was lower than nonwoven fabric material regardless of sealing fabrics. Thermal insulation of aerogel/fiber composite was higher than padding material of nonwoven fabric regardless of sealing fabrics. Compression rate of nonwoven (SP1) was higher than that of aerogel/fiber composite (SP2). Compressive elastic recovery rate of SP1 was also higher than that of SP2, which its compression rate and compressive elastic recovery rate were both poor. As the above result, ultra porous aerogel/fiber composite were proved to be material of good thermal insulation with lower thermal conductivity and also compression rate was proved to be low. Therefore, we can say that aerogel/fiber composite have high possibility to be used as insole materials for cold winter shoes requiring good thermal insulation protection.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.113-122
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• 2021

Complicated residual stress distributions occur in the vicinity of a deposited region via directed energy deposition (DED) process owing to the rapid heating and cooling cycle of the deposited region and the substrate. The residual stress can cause defects and premature failure in the vicinity of the deposited region. Several heat treatment technologies have been extensively researched and applied on the part deposited by the DED process to relieve the residual stress. The aim of this study was to investigate the residual stress characteristics of a specimen fabricated by DED and a quenching process using thermomechanical analyses. A coupled thermomechanical analysis technique was adopted to predict the residual stress distribution in the vicinity of the deposited region subsequent to the quenching step. The results of the finite element (FE) analyses for the deposition and the cooling measures show that the residual stress in the vicinity of the deposited region significantly increases after the completion of the elastic recovery. The results of the FE analyses for the heating and quenching stages further indicate that the residual stress in the vicinity of the deposited region remarkably increases at the initial stage of quenching. In addition, it is observed that the residual stress for quenching is lesser than that after the elastic recovery, irrespective of the deposited material.

• Composites Research
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• v.37 no.4
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• pp.301-309
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• 2024

Shape memory stents are used for treating vascular conditions like myocardial infarction, angina, and arteriosclerosis through their shape memory behavior. These stents are inserted into blood vessels to expand them, and their performance in terms of flexibility, elastic recovery, and deformation is influenced by their design. In this study, parameters affecting stent structural design were analyzed using Taguchi method, aiming to design structures that consider flexibility, elastic recovery, and deformation. Reflecting the actual conditions faced by stents, ISO standards were incorporated, and finite element analysis was conducted, considering shape memory composite material properties obtained from tensile tests, specifically hyperealstic properties. Ultimately, statistical significance of stent structural design was evaluated through ANOVA (Analysis of Variance), and an improved optimal design model compared to the existing one was proposed.

• Journal of the Society of Disaster Information
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• v.15 no.2
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• pp.249-258
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• 2019

Purpose: The purpose of this study is to attain the correlation analysis and thereby to deduce the uniaxial compressive strength of rock specimens through the elastic wave velocity and the elastic modulus among the physical characteristics measured from the rock specimens collected during drilling investigations in Seoul and Gyeonggi region. Method: Experiments were conducted in the laboratory with 119 granite specimens in order to derive the correlation between the compressive strength of the rocks and elastic wave velocity and elastic modulus. Results: In the case of granite, the results of the analysis of the interaction between the compressive strength of a rock and the elastic wave velocity and elastic modulus were found to be less reliable in the relation equation as a whole. And it is believed that the estimation of the compressive strength by the elastic wave velocity and elastic modulus is less used because of the composition of non-homogeneous particles of granite. Conclusion: In this study, the analysis of correlation between the compressive strength of a rock and the elastic wave velocity and elastic modulus was performed with simple regression analysis and multiple regression analysis. The coefficient determination ($R^2$) of simple regression analysis was shown between 0.61 and 0.67. Multiple regression analysis was 0.71. Thus, using multiple regression analysis when estimating compressive strength can increase the reliability of the correlation. Also, in the future, a variety of statistical analysis techniques such as recovery analysis, and artificial neural network analysis, and big data analysis can lead to more reliable results when estimating the compressive sterength of a rock based on the elastic wave velocity and elastic modulus.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.3
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• pp.110-116
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• 1992

Electromgnetic joining of aluminum alloy tubes to high toughness polyurethane rubber cores is studied in order to estimate the joining strength and to analyze the effect of the process variables. The equation which can estimate the joining strength is proposed under considering the elastic recovery of the polyurethane core and the radial shrinkage of the core by pulling it axially. The obtained results are as follows : 1) The joining strength is mainly dependent on the magnitude of residual elastic strain of the polyurethane core. 2) The radial shrinkage (residual strain reduction) of the core during the axial pulling causes the joining strength to decrease severely. The equation for the reduced axial strength is proposed and it is found that the estimated values agree well with experimental results. 3) The magnitude of radial shrinkage could be reduced for the smaller value of ratio l/r. 4) The joining strength in metal/polymer joining increases as the friction coefficient increases. But its effect of friction coefficient is insignificant in comparison with the case of metal/metal joining.