• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.4
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• pp.413-420
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• 2023

Among the seismic structures for reducing earthquake damage, the seismic control structure is a technology that can efficiently improve seismic performance and secure economic feasibility by simply applying a damper. However, existing dampers have limitations in terms of durability due to required seismic performance and material plasticity. In this study, we proposed a polyurethane damper with enhanced recovery characteristics by applying precompression to polyurethane, which basically shows elastic characteristics, and applying superelastic shape memory alloy (SSMA). To verify the characteristics of the polyurethane damper, the concept was first established, and the design details were completed by selecting SSMA and steel, and selecting the precompression size as design variables. In addition, structural tests were conducted to derive response behavior and analyze force resistance performance, residual displacement, recovery rate, and energy dissipation capacity. As a result of the analysis, the polyurethane damper showed that various performances improved when the SSMA wire was applied and the precompression increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.573-580
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• 2008

In this paper, we estimated the effect of the siliceous filler's particle size on the performance of Ultra High Performance Concrete (UHPC). Filler's particle diameters considered in this paper were about 2, 4, 8, 14, $26{\mu}m$ and the performance was evaluated by testing fluidity in fresh concrete, compressive strength, ultimate strain, elastic modulus and flexural strength in hardened concrete. We also carried out XRD and MIP tests to analyze the relationship between the mechanical properties and microstructure. Test results showed that the smaller filler's particle size improves flowability and strength properties. MIP results revealed that the smaller size of filler decreased the porosity and thus increased the strength of UHPC. From XRD analysis, we could find out there were little influence of filler's particle size on chemical reactivity in UHPC.

• Fashion & Textile Research Journal
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• v.25 no.3
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• pp.324-332
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• 2023

Consumers are addressing the issue of dimensional dissatisfaction by repairing clothes, experimenting with style changes, and looking for cost-effective solutions that result in better-fitting garments. This study investigated the repair status by type of clothing, analyzed the method and frequency of repair by type of clothing category and season, and analyzed consumer redesign activities. The findings revealed that upper garments, such as T-shirts, jumpers, jackets, dress shirts, and dresses, were frequently repaired. The common modifications to upper garments included(in order of frequency) shortening sleeve length, shortening overall length, reducing garment width, zipper repair, and adjusting sleeve width. Lower garments, such as pants, jeans, skirts, and training pants, followed in terms of repair frequency. The modifications to lower garments included(in order of frequency) shortening length, reducing width, adjusting waist width (both narrowing and widening), replacing elastic bands, zipper repair, and lengthening. Repairs were more frequently conducted in the order of autumn, winter, spring, and summer. Repair methods varied depending on the clothing type and alterations involved to the length and width of garments and the replacement or removal of old sections. Redesigning clothing as a recycling method was found to enhance the cost-effectiveness of the collection. The study further confirmed the sustainability aspect of redesigning and reusing clothing.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.35-43
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• 2023

In this study, the mechanical properties of concrete mixed with non-sintered hwangto(NHT) as an alternate material for cement were evaluated, and the compressive strength prediction equation of concrete based on ultrasonic pulse velocity analysis was proposed. Cement replacement rates for mixed NHT were set to 0, 15, and 30%, and design compressive strength was set to 30 and 45MPa to evaluate the effect on the amount of cement and NHT powder. The mechanical properties items analyzed were compressive strength, ultrasonic pulse velocity, and elastic modulus, and were measured on days 1, 3, 7, and 28. As the replacement rate of NHT increased, the mechanical properties tended to decrease. In addition, as a result of analyzing the correlation between compressive strength and ultrasonic pulse velocity, the correlation coefficient(R²) showed a high relationship(R²=0.95) on concrete mixed with NHT.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.117-132
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• 2006

The existing analytical solutions for rectangular plates with three edges clamped and the other free are derived based on nondimensional differential equation and their characteristics are analyzed. Since Timoshenko and Woinowsky-Krieger's method (1959) can give solutions for the case limited to the aspect ratio of the plates less than one, this method are proved to be impractical for the bending moment calculation of the plates under consideration. Horii and Moto's method(1968) are modified by adding stabilizing terms to suppress overflow in the matrix computation, from which the series solution with maximum 150 terms can be obtained. By use of the series solution the convergence of computed bending moments is tested. The modified method can be shown to calculate the deflection properties for the plates with wide range of aspect ratios, but the computed x moment at the corner points formed by the free edge and the clamped edges can not satisfy the boundary condition and the cause of problem is discussed in detail.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.267-279
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• 2009

A numerical model that can simulate the nonlinear behavior of ultra high strength fiber reinforced concrete (UHSFRC) structures subjected to monotonic loading is introduced. The material properties of UHSFRC, such as compressive and tensile strength or elastic modulus, are different from normal strength reinforced concrete. The uniaxial compressive stress-strain relationship of UHSFRC is designed on the basis of experimental result, and the equivalent uniaxial stress-strain relationship is introduced for proper estimation of UHSFRC structures. The steel is uniformly distributed over the concrete matrix with particular orientation angle. In advance, this paper introduces a numerical model that can simulate the tension-stiffening behavior of tension part of the axial member on the basis of the bond-slip relationship. The reaction of steel fiber is considered for the numerical model after cracks of the concrete matrix with steel fibers are formed. Finally, the introduced numerical model is validated by comparison with test results for idealized UHSFRC beams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.727-734
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• 2006

Although a limited number of experimental investigations and finite element analyses revealed that a curved web panel in practical design has a considerable reserve strength after the elastic buckling as a straight girder web panel, the current Guide Specifications for Horizontally Curved Steel Girder Highway Bridges (AASHTO, 2003) do not consider the postbuckling strength in the ultimate shear strength due to lack of a comprehensive study. In this study, the ultimate shear strength behavior of horizontally curved steel web panels was investigated through nonlinear finite element analysis and experimental test. It was found that curved web panels used in practical designs are able to develop the postbuckling strength that is equivalent to that of straight girder web panels having the same dimensional and material properties.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.259-266
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• 2009

This study is to develop equations that consider the elastic modulus ratio of FRP bar and steel reinforcement, shear span to depth ratio, and flexural reinforcement ratio of FRP bar, to determine concrete shear strength of FRP reinforced concrete beams without shear reinforcement. As experimental parameters, 2 types of FRP bar, 3 types of shear span to depth ratio, and 3 types of flexural reinforcement were used. Experimental results for two of shear span to depth ratio were quoted from previous study to evaluate effect of shear span to depth ratio in more detail. Shear strength correction factors needed for evaluating concrete shear strength were proposed from regression analysis using above experimental results. Equations suggested from this study and other codes were examined and compared with 31 experimental results available in the literature. From this comparison, it could be known that the equation suggested from this study gives the most approaching result to experimental results.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.36 no.4
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• pp.113-121
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• 2023

Objectives : The purpose of this study is to analyze the treatment mechanism of Thread-embedding acupuncture, which is used in Korean medicine beauty treatment. Methods : After searching papers published up to January 1, 2023 using the keyword "Thread-embedding" through the OASIS site, we selected beauty papers that mentioned the treatment mechanism of Thread-embedding acupuncture. Results : A total of 60 papers were retrieved: 19 papers on the topic of cosmetic diseases, 35 papers on the theme of other diseases, and 6 papers written unrelated to diseases. Among the 19 papers on the topic of cosmetic diseases, one unreadable paper was excluded. Among the 18 papers, we finally selected 6 papers that mentioned treatment mechanisms: 2 on facial wrinkles, 2 on obesity, 1 on breast enlargement, and 1 on transdermal hydration. The treatment mechanism of Thread-embedding acupuncture is that in the case of facial wrinkles, polydioxanone(PDO) is embedded to fill the volume, and as it decomposes, it causes a tissue reaction around the area. In obesity, it promotes fat decomposition by improving circulation, and promotes breast enlargement and elasticity through collagen formation. In transdermal hydration, it induces the production of surrounding fibers to increase skin elasticity and moisture. Conclusions : Thread-embedding acupuncture appears to have a cosmetic effect through a mechanism that promotes the production of collagen and elastic fibers in the subepidermal dermal layer and increases the activity of skin moisturizing factors during the absorption process after the PDO suture is embedded.

• Advances in nano research
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• v.15 no.6
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• pp.567-577
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• 2023

The killing of bacteria by mechanical forces on nanopatterned surfaces has been defined as a mechano-bactericidal effect. Inspired by nature, this method is a new-generation technology that does not cause toxic effects and antibiotic resistance. This study aimed to simulate the mechano-bactericidal effect of nanopatterned surfaces' geometric parameters and material properties against three implant-derived bacterial species. Here, in silico models were developed to explain the interactions between the bacterial cell and the nanopatterned surface. Numerical solutions were performed based on the finite element method. Elastic and creep deformation models of bacterial cells were created. Maximum deformation, maximum stress, maximum strain, as well as mortality of the cells were calculated. The results showed that increasing the peak sharpness and decreasing the width of the nanopatterns increased the maximum deformation, stress, and strain in the walls of the three bacterial cells. The increase in spacing between nanopatterns increased the maximum deformation, stress, and strain in E. coli and P. aeruginosa cell walls it decreased in S. aureus. The decrease in width with the increase in sharpness and spacing increased the mortality of E. coli and P. aeruginosa cells, the same values did not cause mortality in S. aureus cells. In addition, it was determined that using different materials for nanopatterns did not cause a significant change in stress, strain, and deformation. This study will accelerate and promote the production of more efficient mechano-bactericidal implant surfaces by modeling the geometric structures and material properties of nanopatterned surfaces together.