Sung Jun Park

A suit-type wearable robot (STWR) is a new type of soft wearable robot (SWR) that can be worn easily anywhere and anytime to assist the muscular strength of wearers because it can be worn like normal clothes and is comfortable to wear even with no power supply. This paper proposes an STWR, in which a shape-memory-alloy-based fabric muscle (SFM) is used as the actuator. The STWR, which weighs less than 1 kg, has a simple structure, with the following components: SFMs, wire encoders for measuring

Fabric muscle is important for wearable robots that are soft, compliant, and silent with high contractility and high force. This study presents a novel shape memory alloy (SMA) spring-based fabric muscle (SFM). The SFM is manufactured by bundling SMA springs with proven performance as artificial muscle. The SFM generates high contractility and high force, and is soft, flexible, and light because it is covered with fabric used to make actual clothes. The SFM is contracted by heat and shows a cont

We report on a noncontact photoacoustic imaging system utilizing an all-fiber-optic heterodyne interferometer as an acoustic wave detector. The acoustic wave generated by a short laser pulse via the photoacoustic effect and arriving at the sample surface could be detected with the fiber-optic heterodyne interferometer without physical contact or using an impedance matching medium. A phantom experiment was conducted to evaluate the proposed system, and the initial acoustic pressure distribution w

Soft exosuits used for supporting human muscle strength must be lightweight and wearable. Shape memory alloy (SMA) spring-based fabric muscles (SFM) are light and flexible, making them suitable for soft and shape-conformable exosuits. However, SFMs have a slow actuation speed owing to the slow cooling rate of the SMA spring. This paper proposes a forced air-cooling fan-integrated fabric muscle (FCFM) that improves the cooling rate by arranging a thin-diameter SMA spring bundle with a high surfac

We propose and demonstrate the novel method that enables simultaneous measurements of physical thickness and refractive group index without any prior knowledge on samples. The system is based on the spectral-domain optical low coherence interferometry with two sample probes facing each other. Owing to both side measurements schemes, thickness and group refractive index could be measured with not only transparent but also highly absorptive samples. The average errors were ~0.06% in both the physi

Upper limb exosuits (ULEs) are wearable robots that can assist arms to lift or support an object. However, heavy wearable equipment often interferes with the free movement of a person's arms, which have a wide range of motions. This article presents the design and manufacturing processes for a ULE that does not restrict the range of motion of the person wearing it and that can be folded to a small, palm-sized volume for portability. The light and flexible ULE employs a fabric woven from shape me

With the development of material extrusion (ME) technology, ME parts have been widely adopted in various industries owing to their cost-effectiveness. However, air gaps, which are intrinsic problems in the process, are the main reason for the low coalescence, resulting in deteriorating mechanical properties. In addition, the presence of an air gap increases the deviation of the mechanical properties in a build-orientation and worsens the difference in mechanical properties with build orientation

Binder jetting (BJ) leads to low mechanical properties and high porosity because it uses binders to selectively bind powder materials. To overcome the poor characteristics of BJ parts, infiltration is a generally applied post-process; however, it results in a low infiltration volume and large number of residual voids in the uninfiltrated section. This study aims to effectively improve the mechanical properties, microstructure, and density of polymer-based BJ parts by overcoming limitations of in

Abstract This study proposes fabric muscles based on shape memory alloy (SMA) springs coiled with a thin diameter SMA wire of 80 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:mrow> </mml:math> to improve heat dissipation under natural convection and forced air cooling. A new structure and its fabrication process are developed to create soft and flexible fabric muscles capable of supp

Recently, short carbon fiber-reinforced plastic (SFRP) has been selected as a filament material to improve the strength of components fabricated by material extrusion (ME). However, despite the improved material properties, the weak interlayer bonding and voids present in the microstructure constitute defects that cause anisotropy in the SFRP composite and deteriorate its mechanical properties such as the tensile, compressive, and flexural strengths. In this study, warm isostatic pressing (WIP)

Deformation of a grain in polycrystalli ne metals is restricted or forced by deformation of neighbor grains during plastic deformation processes. It also gives influence to deformation of neighbor grains at the same time. Interaction between grains causes inhomogeneous local deformation and texture during plastic deformation. Prediction of inhomogeneous local deformation and texture is important in understanding of recrystallization texture. Taylor-type polycrystal models which have been employe

Abstract Wearable robots use batteries as a power source; therefore, the efficiency of the actuation mechanism must be improved to increase their operation time. Soft wearable robots using fabric-type soft actuators (FSA) have attracted much interest recently. In FSAs, the actuator itself is soft, flexible, and lightweight, and energy must be continuously supplied to support the load and hold the actuation state. In particular, when maintaining a particular posture, such as holding an object, co

Complex liquids flow through channels faster than expected, an effect attributed to the formation of low-viscosity depletion layers at the boundaries. Characterization of depletion layer length scale, concentration, and dynamics has remained elusive due in large part to the lack of suitable real-space experimental techniques. The short length scales associated with depletion layers have traditionally prohibited direct imaging. By overcoming this limitation via adaptations of stimulated emission

This study was designed to evaluate the effect of hospital based rehabilitation exercise program on patients with chronic ankle sprain. For this study, 20 patients with chronic ankle sprain were included. Patients with mechanical instability were excluded. We measured pre and post exercise ankle injury score at all patients. Patients were randomly divided into two groups. 10 patients were treated hospital based rehabilitation exercise program for 3 weeks at 3 times a week, another 10 patie