• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.370-377
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• 2023

Soft and stretchable electronics, equipped with diverse functional devices, have recently garnered attention owing to their versatility in applications such as stretchable displays, flexible batteries, and electronic skin (e-skin). A fundamental challenge in realizing stretchable electronics lies in conferring the necessary flexibility to crucial electrical components such as electrodes and devices. However, the prevalent electronic materials, exhibit limited stretchability, presenting a significant obstacle to the advancement of soft and stretchable electronics. To overcome this challenge, various strategies rooted in geometrical engineering have been explored to enhance the adaptability of rigid materials. This study delves into the realm of geometrical engineering by, examining techniques such as serpentine patterns, kirigami-inspired designs, and island structures, with a keen focus on recent progress and future prospects.

• Composites Research
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• v.37 no.2
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• pp.139-142
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• 2024

This study explores the impact of polymer blending on the mechanical properties and triboelectric energy harvesting capability of composite polymers. A multifunctional free-standing polymer blend composed of poly(vinyl alcohol) (PVA) and poly(diallyldimethylammonium chloride) (PDDA) was fabricated using a polymer casting method. Stress-strain analysis of the polymer blend revealed an enhanced stretchability of 308.4% with excellent transparency. Furthermore, triboelectric analysis revealed dynamic energy harvesting capabilities with impressive electrical voltage and current output of 50 V and 5 μA. These results represent a significant improvement compared to individual PVA and PDDA polymers and highlight the potential of polymer blending to enhance both mechanical and electrical properties for energy harvesting applications.

• Korean Journal of Human Ecology
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• v.22 no.5
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• pp.461-476
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• 2013

This study aims to provide practical information of both color and hands of cotton fabrics dyed with persimmon dye powder for natural dyeing fashion industries by investigating dyeing behavior and color gamut, by testing mechanical properties depending on color characteristics, and finally by evaluating dyeing fastness. As results, the persimmon dye powder obtained by extracting the fruits to final solid powder was found as containing tannin and it partially coated between and on fibers similarly to traditionally dyed one. The K/S values of non-mordanted fabric and two differently mordanted ones with Fe and Cu seemed to reach their equilibrium from 800, 800, and 600% (owf), respectively. Yellow-red was the only one hue shown while tones were various as pale (p), light grayish (ltg), soft (sf), dull (d), grayish (g), and dark grayish (dkg). In mechanical properties, the dyed fabrics with p and ltg tended to be less altered than undyed ones whereas d and d kg by higher bath concentrations could be applied to boxy silhouette owing to their increased stiffness and less stretchability. Although fastness to dry cleaning and stain was good, color change by washing and rubbing needed to be improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.363.1-363.1
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• 2016

Transparent and stretchable conductors are expected to be an essential component in future stretchable optoelectronic devices. Until now, two main methods have been commonly employed to fabricate transparent and stretchable conductors by using metal nanomaterials: creating buckling configurations and creating network configurations. In this report, a novel strategy for obtaining transparent and stretchable conductors is presented, one that employs these two main approaches simultaneously. To the best of our knowledge, this proposed configuration of a buckled long nanofiber network in this study has not yet been reported. In order to provide the transparent conductors with dual mode stretchability originating from simultaneous buckled and network configurations, a buckled Au@polyvinylpyrrolidone (PVP) nanofiber network (hereafter referred to BANN for convenience) was fabricated by transferring Au-metallized electrospun PVP nanofibers onto a prestrained polydimethylsiloxane (PDMS) substrate. Our BANN shows considerably lower strain sensitivity of resistance than that of straight Au@PVP nanofiber network. Durability tests conducted by performing cyclic tensile strain reveal that the relative change in resistance of BANN (prestrain = 20%) is quite small after 1000 cycles. We also demonstrate that this BANN exhibits superior performance over widely used indium tin oxide conductors with regard to high optical transmittance and low sheet resistance.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.224-224
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• 2015

Gel have enormous applicable region due to inherently high stretchability and bio-compatibility. Here, we fabricated highly stretchable electronic conductive organogels which have long-term stability in environment. By introducing a dialysis step which can incorporate conducting polymer, PEDOT, on the procedure of gel synthesis, residual ions inside the gel were removed. In addition, we replaced the water with organic solvent, EG, inside the gels which is high stability in air. Unlike conventional hydrogels, there are no ionic conduction occurred and electrochemically driven current was prevented during electrical voltage was applied. The fabricated organogels are hardly dried during air exposure, and only electrically conductive without any electrochemical reaction at even high voltage. In order to utilize as stretchable conductor, we demonstrated a LED array circuit using the conductive organogels as electrical interconnects. It was successfully operative even stretched up to 300% strain.

• Journal of the Korea Fashion and Costume Design Association
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• v.18 no.1
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• pp.51-60
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• 2016

This study aims to contribute to development of women's incontinence panties with anti-aging effect meeting customers' requirements by examining types, sorts, sizes and specifications of women's incontinence panties currently sold in the market. The results of analysis of a total of 22 commercial products are as follows. 1. Among the samples, 21 incontinence panties were slip on type like regular underwear; only 1 was pad insertion type. With respect to the length of side seam, 17 (77.3%) incontinence panties were above 14 cm which is classified as maxi; the rest of them (5, 22.7%) were 7~11 cm which is classified as middy. 2. With respect to size, the percentage of Size 3 was 40.9% showing the largest, followed by Size 4 (31.8%), Size 2 (18.2%), Size 5 (9.1%). To produce the incontinence panties considering various ages and body shapes, it is recommended to select above Size 4 as a minimum. 3. With respect to materials of the incontinence panties, natural fibers such as cotton or rayon were mostly used and a polyurethane, nylon or polyester was mixed to enhance the wearing sensation and stretchability of the panties. Finally, for structure of the crotch area, single knit was the largest (9, 40.9%), terry weave 7 (31.8%), sofe pile weave 4 (18.2%), and waffle weave or diamond weave 2.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.5
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• pp.901-913
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• 2017

This study analyzed the current state of art by investigating related patents of cycling wear, and suggested fundamental data to develop clothing - originated in Korea. Patent trends were then analyzed after the related patents applied in Korea, USA, and Japan from 1975 to 2015 were extracted using WIPS ON, classified as nation, applicant, technology, use, and technological maturity of the applicant country. The number of patent applications has steadily increased since the 1990s, and has steeply grown since the 2000s. The USA accounted for 55.6% of all collected patents in the study, Japan for 30.6%, and Korea for 13.7%. Technologies related to patterns and functional materials have been dominated by the USA and Japan; however, smart technologies have been actively developed in Korea. According to use, USA focused on functionality, Korea concentrated on safety, and Japan uniformly combined functionality, safety, and convenience. According to the positioning of technology by application, water repellency, stretchability, muscle strengthening, pad, panel, finishing, and weaving technologies were positioned in the functionality.

• Steel and Composite Structures
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• v.35 no.6
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• pp.779-788
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• 2020

Multi-Walled Carbon nanotubes (MWCNT) coupled with Silicone Rubber (SR) can represent applicable strain sensors with accessible materials, which result in good stretchability and great sensitivity. Employing these materials and given the fact that the combination of these two has been addressed in few studies, this study is trying to represent a low-cost, durable and stretchable strain sensor that can perform excellently in a high number of repeated cycles. Great stability was observed during the cyclic test after 2000 cycles. Ultrahigh sensitivity (GF>1227) along with good extensibility (ε>120%) was observed while testing the sensor at different strain rates and the various number of cycles. Further investigation is dedicated to sensor performance in the detection of human body movements. Not only the sensor performance in detecting the small strains like the vibrations on the throat was tested, but also the larger strains as observed in extension/bending of the muscle joints like knee were monitored and recorded. Bearing in mind the applicability and low-cost features, this sensor may become promising in skin-mountable devices to detect the human body motions.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.2
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• pp.268-275
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• 2001

The effects of homogenization conditions and $\beta$-cyclodextrin ($\beta$-CD) on cholesterol removal of Mozzarella cheese were examined. The homogenization pressure influenced markedly on the cholesterol removal in milk and, 75.64% of cholesterol, the highest rate, was removed at $70.0kg/cm^2$. In addition, an increase in temperature resulted in an increase of cholesterol removal in the range of 71.75 to 78.22%. Among different concentrations of $\beta$-CD addition, 1.0% showed 78.21% of cholesterol removal. Therefore, cholesterol-reduced Mozzarella cheese was made by cheese milk treated with 70 $70.0kg/cm^2$ homogenization at $70^{\circ}C$ and 1% $\beta$-CD addition for a subsequent study. The cholesterol reduction of cholesterol-reduced Mozzarella cheese was 63.92%. Meltability, stretchability and oiling-off in cholesterol-reduced cheese were significantly lower than those in control. Hardness, gumminess and chewiness were significantly reduced, while cohesiveness and elasticity increased. Appearance and flavor of the cheese were superior, but texture inferior to the control.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.220-226
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• 2005

To achieve the weight reduction of a vehicle, Magnesium alloys are widely used in automobile parts because of its lightweight characteristics. Magnesium alloys also have advantages in recycling, stiffness, NVH , heat protection. But Magnesium alloy parts are mainly manufactured by diecasting processes, their productivity was not so high compared to by sheet metal working. We are developing vehicle hood using magnesium sheets. In this study we designed magnesium alloy hood which have equivalent mechanical characteristics to steel hood. Using finite element method we decided thickness of magnesium sheets under some design requirements and we changed the shape of hood inner panel and hinge reinforcements. Outer and inner panel thickness was 1.3mm, 1.5mm respectively. Panel dentibility analysis was performed to conform the new magnesium design by nonlinear FEM package. Formability and hemming of Magnesium sheets are the subjects for further study because they have poor stretchability compared to steel sheets.