• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.349-353
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• 2016

The purpose of this study was to investigate possible age differences in the attenuation of acceleration in the upper body (from pelvis through shoulder to head) during fast walking. Thirty young and 29 elderly subjects participated in this study. Wireless acceleration sensors were attached on head, shoulder, and pelvis. Subjects performed two trials of fast walking on a treadmill, where the fast speed was defined as 1.5 times of the comfortable speed. Root-mean-squared (RMS) accelerations of each axis were compared with age group and sensor position as independent factors. In the AP direction, the pelvis acceleration was greater in the young and the shoulder-to-head attenuation was also greater in the young (p<0.001), so that the head acceleration was comparable between age groups (p=0.581). In the ML direction, the pelvis acceleration was greater in the young and also the pelvis-to-shoulder attenuation was greater in the young (p<0.001), so that the head acceleration was greater in the elderly group (p<0.001). Insufficient attenuation ML acceleration in the elderly resulting in the greater acceleration in the head may deteriorate the balance control which utilize feedback signals from the sensory organs in head, e.g., vestibular and visual systems.

• Physical Therapy Rehabilitation Science
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• v.8 no.2
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• pp.93-98
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• 2019

Objective: The purpose of this study was to investigate the effect of robot arm reach training on upper extremity functional movement in chronic stroke survivors. Design: One group pretest-posttest design. Methods: Thirteen chronic stroke survivors participated in this study. Robot arm reach training was performed with a Whole Arm Manipulator (WAM) and a 120-inch projective display to provide visual and auditory feedback. During the robotic arm reach training, WAM provided gravity compensation and assist-as-needed (AAN) force according to the robot control mode. When a participant could not move the arm toward the target for more than 2 seconds, WAM provided AAN force to reach the desired targets. All patients participated in the training for 40 minutes per day, 3 times a week, for 4 weeks. Main outcome measures were the Fugl-Meyer Assessment (FMA), Action Research Arm Test (ARAT) and Box and Block Test (BBT) to assess upper extremity functional movement. Results: After 4 weeks, significant improvement was observed in upper extremity functional movement (FMA: 42.15 to 46.23, BBT: 12.23 to 14.00, p<0.05). In the subscore analysis of the FMA upper extremity motor function domains, significant improvement was observed in upper extremity and coordination/speed units (p<0.05). However, there were no significant differences in the ARAT. Conclusions: This study showed the positive effects of robot arm reach training on upper extremity functional movement in chronic stroke survivors. In particular, we confirmed that robot arm reach training could have a positive influence by leading to improvement of motor recovery of the proximal upper extremity.

• Journal of the HCI Society of Korea
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• v.1 no.1
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• pp.37-44
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• 2006

Specular reflections provide the visual feedback that describes the material type of an object, its local shape, and lighting environment. In photorealistic rendering, there have been a number of research available to render specular reflections effectively based on a local reflection model. In traditional cel animations and cartoons, specular reflections plays important role in representing artistic intentions for an object and its related environment reflections, so the shapes of highlights are quite stylistic. In this paper, we present a method to render and control stylized specular reflections using projective textures based on principal curvature analysis. Specifying a texture as a pattern of a highlight and projecting the texture on the specular region of a given 3D model, we can obtain a stylized representation of specular reflections. For a given polygonal model, a view point, and a light source, we first find the maximum specular intensity point, and then locate the texture projector along the line parallel to the normal vector and passing through the point. The orientation of the projector is determined by the principal directions at the point. Finally, the size of the projection frustum is determined by the principal curvatures corresponding to the principal directions. The proposed method can control the position, orientation, and size of the specular reflection efficiently by translating the projector along the principal directions, rotating the projector about the normal vector, and scaling the principal curvatures, respectively. The method is be applicable to real-time applications such as cartoon style 3D games. We implement the method by Microsoft DirectX 9.0c SDK and programmable vertex/pixel shaders on Nvidia GeForce FX 7800 graphics subsystems. According to our experimental results, we can render and control the stylized specular reflections for a 3D model of several ten thousands of triangles in real-time.

• Journal of Biomedical Engineering Research
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• v.35 no.3
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• pp.50-54
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• 2014

It is being tried to control robot arm using brain signal in the field of brain-machine interface (BMI). This study is focused on applying guidance laws for efficient robot arm control using 3D coordinates obtained from Magnetoencephalography (MEG) signal which represents movement of upper limb. The 3D coordinates obtained from brain signal is inappropriate to be used directly because of the spatial difference between human upper limb and robot arm's end-effector. The spatial difference makes the robot arm to be controlled from a third-person point of view with assist of visual feedback. To resolve this inconvenience, guidance laws which are frequently used for tactical ballistic missile are applied. It could be applied for the users to control robot arm from a first-person point of view which is expected to be more comfortable. The algorithm which enables robot arm to trace MEG signal is provided in this study. The algorithm is simulated and applied to 6-DOF robot arm for verification. The result was satisfactory and demonstrated a possibility in decreasing the training period and increasing the rate of success for certain tasks such as gripping object.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.562-568
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• 2016

This study to investigated the therapeutic effect of robot-assisted rehabilitation (Lokomat) with virtual reality (VR) on Pusher syndrome (PS) after stroke. A total of 10 patients presented with PS after stroke were recruited. The participants were divided into two groups: Lokomat (n=5) and control groups (n=5). Lokomat and conventional physical therapy (CPT) were performed together in the experimental group, and the patients in the control group were treated with CPT only twice a day. One session of intervention was carried out for 30 minutes five times per week for 4 weeks. Scale for contraversive pushing (SCP), Berg balance scale (BBS), falling index (FI), and Timed up and go test (TUG) were measured before and after the intervention. The Lokomat group produced significantly better outcomes in SCP (p=0.046), BBS (p=0.046), FI (p=0.038), and TUG (p=0.038) compared with the control group after 4 weeks of intervention. In addition, there were significant correlations between SCP and BBS (p=0.024), FI (p=0.039), and TUG (p=0.030). In conclusion, Lokomat with VR more effectively aided recovery from PS after stroke, and restoration of PS symptoms was related with improvement of balance and gait function.

• 한국노년학
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• v.29 no.4
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• pp.1261-1275
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• 2009

Age related decrease of muscle strength, balance, and gait abilities bring about physical inactivity in the elderly. Virtual reality (VR) training has been used successfully to rehabilitate functional balance and mobility in elderly subjects. This study was aimed at determining the effect of VR-based exercise programs by using a video game on the muscle strength, balance, and gait abilities in the elderly. 48 old people were randomly divided into two groups; VR-group (men: 11, women: 14, age: 68.42yrs) and control group (men: 10, women: 13, age: 67.58yrs). VR-group performed an exercise program twice a week for 8 weeks and control group had no intervention. The VR-based exercise program was composed of warm up(10 mins), VR-program(40 mins), and cool down(10mins). It was performed by playstation eyetoy play that provided visual and auditory feedback as well as movements of the upper and lower extremities. Muscle strengths of the knee and ankle were measured using manual muscle tester. Static balance was estimated using computerized posturography. Dynamic balance was measured by Timed up and go test (TUG), Functional reach test (FRT). 10m walk test and 6-min walk test were used to assess gait abilities. After the completion of the VR-exercise program, muscle strength, balance, and gait abilities were improved significantly (p<0.05). In conclusion, the VR-based exercise program showed improvement on the muscle strength, balance, and gait ability in the elderly. This exercise program is both effective and interesting for this age group.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.3
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• pp.207-214
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• 2017

The problem of trunk stability is a major factor in back pain.. Abdominal draw in maneuver(ADIM), One of the trunk stabilization exercises to relieve lumbar instability, is a method of inducing selective contraction of the transverse abdominis associated with anticipatory posture control among the abdominal stabilization muscles. ADIM is usually performed with a visual feedback by applying a pressure biofeedback unit(PBU) under the lumbar at the supine position, which is not functional compared to the sitting position. This study was conducted to investigate the effect of ADIM applied in supine and sitting position on 31 healthy men and women. In each posture, muscle activity was measured by rectal abdominis (RA), external oblique (EO), transverse abdominis (TrA)/internal obilique (IO) and erector spinae (ES) using wireless EMG. In the result, there was no significant difference between RA and EO between the two postures and there was a significant difference between TrA / IO and ES. In both postures, the activity of TrA/IO was higher than that of RA, and the effect of ADIM was shown to be the same, whereas TrA/IO and ES showed higher activity in sitting position. This means that the activity of the muscles involved in the postural stability and lumbar stability is increased further in the sitting position. Therefore, ADIM in sitting, which can be applied more easily in daily life, is useful for improving lumbar stability.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.57-66
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• 2005

In this paper, a new rehabilitation training system was developed to improve equilibrium sense by combining virtual reality technology with a fixed exercise bicycle. The subjects consisted of two groups. A group of young people, was compared against a group of elderly. We measured three different running modes of virtual bicycle system with two successive sets. The parameters measured were running time, velocity, the weight movement, the degree of the deviation from the road, and the variables about the center of pressure. The repeated training, our results showed that the running capability of the elderly improve compared. In addition, it was found out that the ability of postural control and the equilibrium sense was improved with the presentation of the visual feedback information of the distribution of weight. From the results of this experiment, we showed that our newly developed system might be useful in the diagnosis of equilibrium sense or in the improvement of the sense of sight and, somatic, and vestibular sense of the elderly in the field of rehabilitation training.