• International journal of advanced smart convergence
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• v.9 no.1
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• pp.202-208
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• 2020

Body balance necessary for ordinary daily activities can be undermined by diverse causes. In this study, as a way to control such a problem, we have produced smart insole as a wearable device in the form of insole and developed analysis software evaluating body balance, which measures ground reaction force applied to each area of sole and Center of Pressure (COP). The software visualized changes in COP positions while a user was moving and average COP positions, and it is also capable of measuring the COP values in the Anterior-Posterior (AP) and Medial-Lateral (ML) areas of feet. Through gait analysis, it can analyze the time of walking, strides, speed, COP trajectory while walking, etc. In addition, we have developed training contents for body balance improvement designed in consideration of Y-Balance Test and Timed Up and Go (TUG) Test. They were established in virtual reality similar to daily living environment so that people can expect more effective training results regardless of places.

• Advances in aircraft and spacecraft science
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• v.11 no.2
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• pp.177-194
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• 2024

The objective of this paper is to compute entire flow field over Apollo-II, Aerospace Reentry Demonstrator (ARD), Orbital Experiment (OREX) with sharp shoulder and rounded shape shoulder and Space Recovery Experiment (SRE) at different flare-cone half-angle of 20° and 35°. This paper addresses numerical solutions of the compressible three-dimensional Euler equations on hexahedral meshes for a freestream Mach 6 and at an angle of incidence 5°. Furthermore, spatial discretization is accomplished by a cell centred finite volume formulation solution and advanced in time by an explicit multi-stage Runge-Kutta method. The flow field characteristics, distribution of surface pressure coefficient and Mach number on fore-body and aft-body are presented as a function of the geometrical parameters of many reentry capsules. The surface pressure variation is numerically integrated to obtain the aerodynamic drag and compared well with impact theory. The present numerical study has observed the significant dependence of the blunt body and the aft-body geometry of the vehicle and can be used to study atmospheric conditions during re-entry trajectory. The numerical analysis reveals the significant influence of capsule geometry on the flow characteristics of the mechanism of upstream and structure of the flow near the wake region and aerodynamic drag coefficient.

• Journal of Biomedical Engineering Research
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• v.31 no.6
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• pp.487-493
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• 2010

In this study, the circular friction massage technique was performed on the trapezius, the levator scapulae, and the deltoid muscles to collect the information on massage pressures and positions, and thus to utilize it in professional massage system design. Massage motion was measured with the 3-D motion capture system and finger pressures were simultaneously obtained with grip sensors. Massage motions, pressure patterns, and pressure times were different on each muscle, and the motion trajectory was similar to the ellipsoidal shape. The trapezius had higher pressure, longer massage time, and larger impulse than other muscles. These results could be useful to design a massage system based on biomechanical analysis. In order to improve massage effect, it is also strongly recommended that the tip of the system be similar with that of a human thumb in shape and material.

• Journal of Korean Neurosurgical Society
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• v.29 no.6
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• pp.738-743
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• 2000

Objectives : The less invasive stereotactic surgery of hypertensive intracerebral hematoma has been preferred. Many techniques were developed to facilitate aspiration of a dense blood clot in acute stage. Authors describe a method for evacuation of putaminal hematoma via computerized tomography(CT)-aided free-hand stereotactic infusion of urokinase and frequent negative pressure aspiration. Patients and Methods : A total of ten patients with spontaneous putaminal hematoma underwent surgery with negative pressure aspiration in the three-year period. All procedures were performed within 12 hours of insult. A silicone ventricular catheter was inserted into the center of hematoma through a burr hole at the Kocher's point under local anesthesia. In a typical case of putaminal hematoma, the trajectory of catheter was pointed the center of hematoma parallel to sagittal plane vertically and the external auditory meatus posteriorly. Immediately after the first trial of hematoma aspiration low-dose urokinase solution(2,000IU/5ml saline) was administrated through the catheter and drain was clipped for 30 minutes. Subsequently, the partially liquified hematoma was manually aspirated using a 10ml syringe with a negative pressure of less than 2 to 3ml. The procedure was carefully repeated every 1 hour until the hematoma was near totally evacuated. Results : The patients population consisted composed of 4 men and 6 women with a mean age of 61.6 years. All had major neurological deficits preoperatively. The mean hematoma volume was 44.3 ml and hematoma was drained for 20 to 48 hours. No complications such as rebleeding, meningitis, or malplaced catheter were noted. Outcome was moderately disabled in four patients and good recovery in three patients. Conclusion : Although the frequent negative pressure aspiration and low-dose urokinase infusion has the disadvantage of possbility of rebleeding and infection, it is consisdered to be an effective method because it allows a simple, safe, and complete removal of hematoma.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.235-244
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• 2022

Objective: The aim of this study was to investigate of the foot plantar pressure and usability after gait training using the ExoAtlet wearable exoskeleton robot in an incomplete spinal cord injury (SCI) patient. Design: A case study Methods: Six participants with an asymmetry in motor and sensory function completed the gait training using ExoAtlet wearable exoskeleton robot for 15 sessions, five per weeks, 3weeks. They were divided into two groups (low and high strength group) and group differences were evaluated about session at stating of gait, gait distance at final session and foot plantar pressures and useability after training. Results: Low strength group was faster than high strength group on adaptation of robot gait. And high strength group increased faster than low strength group on the gait distance during training. In standing and gait, weaker leg was higher than stronger leg on mean foot plantar pressure in low strength group. And stronger leg was higher than weaker leg on foot plantar pressure in high strength group. The length of the anterior-posterior trajectory of the center of pressure during gait was similar in low strength group, but different in high strength group. useability was positive about ExoAtlet wearable exoskeleton gait after training. Conclusions: ExoAtlet wearable exoskeleton robot gait training was positive about improving gait in all participants regardless of differences in severity of symptoms and gait abnormalities.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.165-170
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• 1997

In this paper, we consider the aortic sinus baroreceptor, which is the most representative baroreceptors sensing the variance of pressure in the cardiovascular system(CVS), and propose heart activity control model to observe the effect of delay time in heart period and stroke volume under the regulation of baroreflex in arotic sinus. The proposed heart activity baroreflex regulation model contains CVS electric circuit sub-model, baroreflex regulation sub-model and time delay sub-model. In these models, applied electric circuit sub-model is researched by B.C.Choi and the baroreflex regulation sub-model transforms the input, the arotic pressure of CVS electric circuit sub-model, to outputs, heart period and stroke volume by mathematical nonlinear feedback. We constituted the time delay sub-model to observe sensitivity of heart activity baroreflex regulation model by using the variable value to represent the control signal transmission time from the output of baroreflex regulation model to efferent nerve through central nervous system. The simulation object of this model is to observe variability of the CVS by variable value in time delay sub-model. As simulation results, we observe three patterns of CVS variability by the time delay. First, if the time delay is over 2.5 sec, arotic pressure, stroke volume and heart rate is observed nonperiodically and irregularly. Second, if the time delay is from between 0.1 sec and 0.25 sec, the regular oscillation is observed. Finally, if time delay is under 0.1 sec, then heart rate and arotic pressure-heart rate trajectory is maintained in stable state.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1121-1136
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• 2002

The flow characteristics of film coolant issuing into turbulent boundary layer developing on a convex surface have been investigated by means of flow visualization and three-dimensional velocity measurement. The Schlieren optical system with a spark light source was adopted to visualize the jet trajectory injected at 35° and 90° inclination angles. A five-hole directional pressure probe was used to measure three-dimensional mean velocity components at the injection angle of 35°. Flow visualization shows that at the 90° injection, the jet flow is greatly changed near the jet exit due to strong interaction with the crossflow. On the other hand, the balance between radial pressure gradient and centrifugal force plays an important role to govern the jet flow at the 35° injection. The velocity measurement shows that at a velocity ratio of 0.5, the curvature stabilizes downstream flow, which results in weakening of the bound vortex structure. However, the injectant flow is separated from the convex wall gradually, and the bound vortex maintains its structure far downstream at a velocity ratio of 1.98 with two pairs of counter rotating vortices.

• Ocean Systems Engineering
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• v.8 no.2
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• pp.223-246
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• 2018

In this paper the results of CFD simulations, that were carried out to study the impact pressures acting on a symmetric wedge during water entry under the influence of gravity, are presented. The simulations were done using a solver implementing finite volume discretization and using the VOF scheme to keep track of the free surface during water entry. The parameters such as pressure on impact, displacement, velocity, acceleration and net hydrodynamic forces, etc., which govern the water entry process are monitored during the initial stage of water entry. In addition, the results of the complete water entry process of wedges covering the initial stage where the impact pressure reaches its maximum as well as the late stage that covers the rebound process of the buoyant wedge are presented. The study was conducted for a few touchdown velocities to understand its influence on the water entry phenomenon. The simulation results are compared with the experimental measurements available in the literature with good accuracy. The various computational parameters (e.g., mesh size, time step, solver, etc.) that are necessary for accurate prediction of impact pressures, as well as the entry-exit trajectory, are discussed.

• Journal of Ship and Ocean Technology
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• v.1 no.2
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• pp.19-30
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• 1997

The accurate prediction of the flow and the pressure distribution near the tip of the blade is crucial in determining the tip vortex cavitation inception which usually occurs on the blade tip or inside the core of the tip vortex just downstream of the blade tip. An improved boundary element method is applied to the prediction of the flow around propeller blades, with emphasis at the tip region. In the method, the Blow adapted grid and a higher order panel method, which combines a hyperboloidal panel geometry with a hi-quadratic dipole distribution, are used in order to accurately model the trailing wake geometry and the highly rolled-up regions in the wake. The method is applied to several propeller geometries and the results have been found to agree well to the existing experimental data. Inviscid flow methods are able to predict the pressures at the tip as well as the shape of the trailing wake. On the other hand, they are unable to determine the flow inside the viscous core of the tip vortex, where cavitation inception often occurs. Thus, a method is presented that treats the flow inside the viscous core. The inner flow is treated with a 2-D Clavier-stokes solution without making any assumptions for axisymmetric flow and conicity of the flow along the tip trajectory. The method can thus allow the treatment of general propeller blade configurations. The velocity and pressure distributions inside the core are shown and compared to those from other numerical methods.

• Particle and aerosol research
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• v.5 no.3
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• pp.123-131
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• 2009

This paper presents simulation results of particle transport in low-pressure, low-temperature plasma environment. The size dependent transport of particles in the plasma is investigated with a two-dimensional simulation tool developed in-house for plasma chamber analysis and design. The plasma model consists of the first two and three moments of the Boltzmann equation for ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The particle transport model takes into account all important factors, such as gravitational, electrostatic, ion drag, neutral drag and Brownian forces, affecting the motion of particles in the plasma environment. The particle transport model coupled with both neutral fluid and plasma models is simulated through a Lagrangian approach tracking the individual trajectory of each particle by taking a force balance on the particle. The size dependant trap locations of particles ranging from a few nm to a few ${\mu}m$ are identified in both electropositive and electronegative plasmas. The simulation results show that particles are trapped at locations where the forces acting on them balance. While fine particles tend to be trapped in the bulk, large particles accumulate near bottom sheath boundaries and around material interfaces, such as wafer and electrode edges where a sudden change in electric field occurs. Overall, small particles form a "dome" shape around the center of the plasma reactor and are also trapped in a "ring" near the radial sheath boundaries, while larger particles accumulate only in the "ring". These simulation results are qualitatively in good agreement with experimental observation.