• Molecules and Cells
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• v.42 no.10
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• pp.729-738
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• 2019

Autophagy is an important process for protein recycling. Oligomerization of p62/SQSTM1 is an essential step in this process and is achieved in two steps. Phox and Bem1p (PB1) domains can oligomerize through both basic and acidic surfaces in each molecule. The ZZ-type zinc finger (ZZ) domain binds to target proteins and promotes higher-oligomerization of p62. This mechanism is an important step in routing target proteins to the autophagosome. Here, we determined the crystal structure of the PB1 homo-dimer and modeled the p62 PB1 oligomers. These oligomer models were represented by a cylindrical helix and were compared with the previously determined electron microscopic map of a PB1 oligomer. To accurately compare, we mathematically calculated the lead length and radius of the helical oligomers. Our PB1 oligomer model fits the electron microscopy map and is both bendable and stretchable as a flexible helical filament.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.401-415
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• 2021

Soft robots are promising devices for applications in drug delivery, sensing, and manufacturing. Traditional hard robotics are manufactured with rigid materials and their degrees of motion are constrained by the orientation of the joints. In contrast to rigid counterpart, soft robotics, employing soft and stretchable materials that easily deforms in shape, can realize complex motions (i.e., locomotion, swimming, and grappling) with a simple structure, and easily adapt to dynamic environment. Among them, the magnetic actuators exhibit unique characteristics such as rapid and accurate motion control, biocompatibility, and facile remote controllability, which make them promising candidates for the next-generation soft robots. Especially, the magnetic actuators instantly response to the stimuli, and show no-hysteresis during the recovery process, essential for continuous motion control. Here, we present the state-of-the-art fabrication process of magnetically controllable nano-/micro-composites, magnetically aligning process of the composites, and 1-dimensional/multi-dimensional multimodal motion control for the nextgeneration soft actuators.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.31-35
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• 2017

We have fabricated flexible and stretchable pressure sensors using silver nanowires (AgNWs) and analyzed their electric responses. AgNWs are spray coated directly onto uncured polydimethylsiloxane (PDMS) such that AgNWs penetrate into the uncured PDMS, enhancing the adhesion properties of AgNWs. However, the single-layered AgNW sensor exhibits unstable electric response and low pressure sensitivity. To tackle it, we have coated a conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) onto the AgNW layer. Such a hybrid bilayer sensor ensures a stable electric response because the over-coating layer of PEDOT:PSS effectively suppresses the protrusion of AgNWs from PDMS during release. To enhance the sensitivity further, we have also fabricated a stacked bilayer AgNW sensor. However, its electric response varies depending sensitively on the initial overlap pressure.

• Journal of Hydrogen and New Energy
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• v.29 no.6
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• Journal of Korean Living Environment System
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• v.24 no.4
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• pp.533-540
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• 2017

This study analyzes the stretchability and clothing pressure of fabrics made from stretchy knit materials, and uses the baseline data to develop various functional clothing made from stretchy knit fabrics. To observe the changes in the stretchability and clothing pressure, we observed the compatibility of the two materials (tricot and power-net), presence of flat seam, fabric layering, and flat seam direction as key variables. A standard test method for stretch properties (ASTM D2594) was used for measuring the stretchability of the material. Clothing pressure measurements were analyzed in terms of the mean and standard deviation values, and the correlation of the stretchability. In the case of tricot, the presence of flat seam increased the stretchability of the fabric regardless of the fabric layering. However, when tricot and the less stretchable power-net were combined, the presence of flat seam did not increase the stretchability. Flat seam did not interfere with or limit the stretchability of the fabric, but they did increase the clothing pressure at the seam. The stretchability had a negative correlation with the clothing pressure except along the flat seam.

• Current Optics and Photonics
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• v.4 no.6
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• pp.477-482
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• 2020

Recently, one of the authors has been reported an optically tunable fiber Bragg grating (FBG) with a photomechanical polymer. It was based on a typical FBG with a downsized diameter of 60 ㎛, coated with azobenzene-containing polymer material. Azobenzene is a well-known reversibly photomechanical stretchable material under ultraviolet (UV) light. The small part of the functional-coating region on the FBG absorbed UV light, which pulled the UV-exposed part of the grating. It was selectable as tunable FBG or tunable chirped FBG, by adjusting the position of UV exposure on the grating. As proof of concept for the tunable FBG device, the characteristics just including UV-induced center-wavelength shift and spectral-width changes of the device were reported. In this paper, we report for the first time that the microactuator makes it possible to control the spectral shape of the FBG reflection, according to the specifications (shape and intensity) of the UV beam that reaches the FBG coated with the azobenzene polymer. In addition, we provide the group-delay profiles for the chirped FBG, so that the sign of its dispersion (normal or anomalous) can be tailored by simply selecting the moving direction of the UV light's displacement in the experiment.

• Electronics and Telecommunications Trends
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• v.37 no.2
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• pp.30-41
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• 2022

As the society is superaging, the number of patients with movement disabilities due to musculoskeletal or nervous system illness is rapidly increasing. To improve public health and reduce medical expenses, it is essential to develop rehabilitation systems that allow patients to resume their daily-life activities. However, the existing musculoskeletal illness diagnosis and rehabilitation method is limited in terms of precision and efficiency because it is based on an empirical diagnosis and prescription without regard for individual characteristics. To overcome these limits, it is critical to design a novel concept of routine rehabilitation therapy device that is capable of inducing musculoskeletal balance by the precise analysis of musculoskeletal usage patterns via the motion and the muscle activity tracking of linked muscles. This study introduces the trend of on-skin sensor device technology for routine musculoskeletal monitoring and therapy. For on-skin rehabilitation systems, skin-adhesive and stretchable motion/posture, electromyography, pressure sensors, small-size and low-power wireless sensor interfaces, and user-friendly rehabilitation contents based on new algorithms are combined.

• Fashion & Textile Research Journal
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• v.24 no.2
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• pp.241-248
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• 2022

This study aims to provide basic data to suggest guidelines for re-education and work improvement of modelists based on the analysis of the current status of modelist work and education. A survey was conducted from January 4 to May 15, 2020, targeting 44 people working in pattern, pattern CAD, and grading in domestic apparel companies. Descriptive statistical analysis and frequency analysis using SPSS 25 were employed to analyze the status of work type, work difficulties, and re-education. For pattern production, the rate of using pattern CAD for business was high. It was found that companies mainly use YUKA CAD (63.8%), and branded companies use pattern CAD (100%). It was found that 3D CAD is mostly employed by vendors (88.9%), and CLO (90%) is mainly used. Regarding difficulties in pattern making, it was found that they experienced difficulties with stretchable materials owing to the amount of shrinkage and sagging of the fabric. The work problem was the lack of requisite working hours owing to the volume of work. Regarding future re-education, 63.6% of the total respondents indicated that they required a course related to pattern correction and material. Moreover, it was found that re-education was necessary to upgrade technology and acquire new knowledge, however, information on re-education was insufficient.

• Journal of Adhesion and Interface
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• v.24 no.2
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• pp.41-53
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• 2023

The deformable devices refer to the devices that can maintain their initial performance even when stretched or bent. Among the materials used as conductor in deformable devices, Ga-based liquid metal is one of the most promising materials because it can provide not only high conductivity and deformability but also low toxicity. In this paper, we introduce Ga-based liquid metals and then discuss the recent research trend in deformable devices composed of Ga-based liquid metal.

• Journal of Sensor Science and Technology
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• v.33 no.1
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• pp.7-11
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• 2024

Soft-pressure sensors have numerous applications in soft robotics, biomedical devices, and wearable smart devices. Herein, we present a highly sensitive electronic skin device with an isotropic wrinkled pressure sensor. A conductive ink for soft pressure sensors is produced by a solution process using polydimethylsiloxane (PDMS), poly 3-hexylthiophene (P3HT), carbon black, and chloroform as the solvents. P3HT provides high reproducibility and conductivity by improving the ink dispersibility. The conductivity of the ink is optimized by adjusting the composition of the carbon black and PDMS. Soft lithography is used to fabricate a conductive elastic structure with an isotropic wrinkled structure. Two conductive elastic structures with an isotropic wrinkle structure is stacked to develop a pressure sensor, and it is confirmed that the isotropic wrinkle structure is more sensitive to pressure than when two elastic structures with an anisotropic wrinkle structure are overlapped. Specifically, the pressure sensor fabricated with an isotropic wrinkled structure can detect extremely low pressures (1.25 Pa). Additionally, the sensor has a high sensitivity of 15.547 kpa^-1 from 1.25 to 2500 Pa and a linear sensitivity of 5.15 kPa^-1 from 2500 Pa to 25 kPa.