Yongsoon Yoon

The effect of electric cortical stimulation after focal traumatic brain injury in rats.

Objective To evaluate the effects of electric cortical stimulation in the experimentally induced focal traumatic brain injury (TBI) rat model on motor recovery and plasticity of the injured brain. Method Twenty male Sprague-Dawley rats were pre-trained on a single pellet reaching task (SPRT) and on a Rotarod task (RRT) for 14 days. Then, the TBI model was induced by a weight drop device (40 g in weight, 25 cm in height) on the dominant motor cortex, and the electrode was implanted over the perilesional cortical surface. All rats were divided into two groups as follows: Electrical stimulation (ES) group with anodal continuous stimulation (50 Hz and 194 µs duration) or Sham-operated control (SOC) group with no electrical stimulation. The rats were trained SPRT and RRT for 14 days for rehabilitation and measured Garcias neurologic examination. Histopathological and immunostaining evaluations were performed after the experiment. Results There were no differences in the slice number in the histological analysis. Garcias neurologic scores & SPRT were significantly increased in the ES group (p<0.05), yet, there was no difference in RRT in both groups. The ES group showed more expression of c-Fos around the brain injured area than the SOC group. Conclusion Electric cortical stimulation with rehabilitation is considered to be one of the trial methods for motor recovery in TBI. However, more studies should be conducted for the TBI model in order to establish better stimulation methods.

Formation flight control under communication failure

This paper presents the management of UAV formation flight with respect to varying levels of communication among UAVs. Inter-vehicle communication in the formation is a critical issue because each UAV needs the information on other vehicles for formation. However, since communication is not perfect in reality, the formation performance under communication failure has to be analyzed. This study uses position data measured by sensors for overcoming communication failures in the standard leader-follower structure formulated in the nonlinear model predictive control (NMPC) framework. The perceived and obtained position data of each UAVs through GPS or sensor are noisy. These are estimated by extended Kalman filter. The numerical simulation results support the feasibility of the proposed formation flight method.

Obstacle Avoidance for Wheeled Robots in Unknown Environments Using Model Predictive Control

Abstract This paper presents a model predictive approach for obstacle avoidance of car-like unmanned ground vehicles (UGVs). An optimal tracking problem while avoiding obstacles in unknown environments is formulated in terms of cost minimization under constraints. Information on obstacles can be incorporated online in the nonlinear model predictive framework and kinematic constraints are treated by Karush-Kuhn-Tucker (KKT) condition. The overall problem is solved real-time with nonlinear programming. This approach is applied to car-like robots including tire models while explicitly considering the dimension of the UGV rather than treating it as a dimensionless cart model. Two kinds of potential-like terms are employed in the cost function for obstacles avoidance. The first term is to consider the distance between the UGV and the obstacle, and the second one is to consider the parallax information of the UGV about the obstacles. Simulation results show that both two approaches can make safe steering in a simple environment, but in a complex environment such as an urban area, the approach based on the modified parallax (MP) was more successful in the view of the computation time and safe steering.

Communication in distributed model predictive collision avoidance

This paper presents a model predictive approach for collision avoidance of car-like robots. An optimal problem is formulated in terms of cost minimization under constraints. Information on each robot can be incorporated online in the nonlinear model predictive framework and kinematic constraints are treated by Karush-Kuhn-Tucker(KKT) condition. For distributed collision avoidance of multiple robots with two levels of a communication network, performances are compared. In comparison with different types of communication, how much information the robots share can cause difference in the performance. More successful collision avoidance was possible when the robots share enough amount of information.

Relationship Between HbA1c and Complex Regional Pain Syndrome in Stroke Patients With Type 2 Diabetes Mellitus

Objective To investigate the relationship between glycosylated hemoglobin A (HbA1c) and complex regional pain syndrome (CRPS) in stroke patients with type 2 diabetes mellitus (T2DM). Methods A retrospective chart review was performed of stroke patients from January 2012 to December 2013. We reviewed 331 patients and included 200 in the analysis. We divided them into CRPS and non-CRPS groups and compared them by age, gender, stroke lesion, cause of stroke, duration of T2DM, HbA1c (%), National Institutes of Health Stroke Scale score, affected shoulder flexor muscle strength, Fugl-Meyer Assessment score, motricity index, Functional Independence Measure, Korean version of Modified Barthel Index, blood glucose level on admission day, duration from stroke onset to HbA1c check, and duration from stroke onset to three-phase bone scan for CRPS diagnosis. Thereafter, we classified the patients into five groups by HbA1c level (group 1, 5.0%–5.9%; group 2, 6.0%–6.9%; group 3, 7.0%–7.9%; group 4, 8.0%–8.9%; and group 5, 9.0%–9.9%) and we investigated the difference in CRPS prevalence between the two groups. Results Of the 200 patients, 108 were in the CRPS group and 92 were in the non-CRPS group. There were significant differences in HbA1c (p<0.05) between the two groups but no significant differences in any other factors. Across the five HbA1c groups, there were significant differences in CRPS prevalence (p<0.01); specifically, it increased as HbA1c increased. Conclusion This study suggests that higher HbA1c relates to higher CRPS prevalence and thus that uncontrolled blood glucose can affect CRPS occurrence in stroke patients with diabetes.

Model predictive control for drivability enhancement with input dead-segment

Optimization between comfortability and an accelerating power which drivers desire is a significant issue in powertrain control. When torque demand of the drivers changes drastically, like tip-in/out, the drivers experience severe vibrations called jerking. Although torque reduction up to a certain extent alleviates the vibration of drive shaft, an excessive reduction deteriorates a power of acceleration. In this paper, optimal suppression of unpleasant vibration in a drive shaft will be presented via a model predictive control (MPC). As output variables to be tracked in MPC scheme, torsion angle and its rate are considered with analysis of dynamical characteristics. The proposed approach takes into account inherent input dead-segment of internal combustion engines. Simulation results show that the suggested MPC approach for active torque control suppresses the vibration of driveline efficiently while avoiding a critical loss of accelerating power.

Poster 73 Gait Training with the Newly Developed Active-Assistive System for Gait is Feasible for Hemiplegic Patients after Stroke

Case Description: A 66-year-old previously independent man presented with sudden onset severe left shoulder pain that radiated down his left arm, across the lower neck and upper back, and to the right shoulder. Within 4 hours, he gradually developed upper and lower extremity weakness, diffuse paresthesia, and truncal ataxia. Electrocardiography, magnetic resonance imaging of the cervical and lumbar spine, computed tomography scan of the chest and abdomen, and lumbar puncture were non-revealing. A spinal angiogram revealed stenosis of L2 radicular artery caused by compression from the right diaphragmatic crus. Steroids, heparin, and phenylephrine were initiated. Dissection of the diaphragmatic crus via a right peritoneal approach was done to revascularize the spinal cord. He was admitted to acute inpatient rehabilitation (AIR) hospital for interdisciplinary rehabilitation care. Setting: Acute inpatient rehabilitation hospital. Results or Clinical Course: Upon discharge from AIR, he was able to walk 20 feet on the zero G suspension system using 20 percent body weight support, propel a wheelchair 500 feet using bilateral upper extremities, perform activities of daily living with minimal assistance, and use sliding board for transfers. Discussion: This report adds to the few documented cases of a spinal cord injury caused by compression of a diaphragmatic crus on a radicular artery. Conclusion: Spinal cord ischemia may be caused by compression of the radicular artery by the diaphragmatic crus. Diagnosis is made via spinal angiography and definitive cure is via resection of the diaphragmatic crus. It is important to have a high level of suspicion that would lead to early diagnosis and treatment to improve functional outcomes.

The Effect of Electrical Stimulation Combined with Foam Dressing on Ulcer Healing in Rats with Spinal Cord Injury.

OBJECTIVE: To evaluate the effect of electrical stimulation (ES) combined with foam dressing on wound healing in rats with spinal cord injury. METHODS: Complete spinal cord injury was induced in 49 male Sprague-Dawley rats at the T11-L1 level, after which a pressure ulcer was induced on the left thigh. The newly invented surface electrode, which was fitted with foam inside, was applied to the ulcers. Rats were divided into 2 groups as follows: the ES group, which received foam dressings and ES (2 Hz and 200-microsecond duration, 15 mA) for 4 times a day, 30 minutes each, for 3 weeks; and the control group, which received the foam dressings without ES. The ulcer area was measured by taking a photograph daily from day 0 to day 21. Histopathologic and immune-histochemical evaluations were performed on day 1 and days 7, 14, and 21. RESULTS: The area of the ulcers of the ES group was smaller than that of the control group after day 14 (P < .05). In the ES group, the vascularity was significantly greater on day 14 and more decreased on day 21 compared with day 7 than that in the control group (P < .05). In the ES group, the area of positive reaction to anti-&agr;–SMA antibody was increased compared with the control group on days 7 and 14 and decreased on day 21 (P > .05). CONCLUSION: Electrical stimulation combined with foam dressing by means of newly invented surface electrodes facilitates and accelerates the wound-healing process.

Balloon Dilatation for an Esophageal Stricture by Long-Term Use of a Nasogastric Tube: A Case Report

In the present report, we describe a case of long-term follow-up esophageal stricture occurring in a patient with nasogastric tube use. A 63-year-old man who had experienced dislocation of the 6th and 7th cervical vertebrae as the result of an external injury received treatment at another hospital and was admitted to the rehabilitation department of our hospital. After he exhibited normal swallowing in a videofluoroscopic swallowing test, the nasogastric tube was removed and oral feeding with a dysphagia diet was initiated. However, during oral feeding, the patient complained of swallowing difficulties in his lower throat. An esophagogastroduodenoscopy was performed to examine the lesions below the pharynx and a 2-mm stricture was observed. A balloon dilatation was performed for a total of 9 times to extend the stricture. After the procedure, the patient was able to easily swallow a normal diet through the esophagus and the vomiting symptoms disappeared. An esophagography showed that the diameter of the esophageal stricture was 11 mm.

Safe steering of UGVs in polygonal environments

This paper presents an application of a model predictive control for trajectory generation of an unmanned ground vehicle. An optimal tracking problem while avoiding collision with obstacles is formulated in terms of cost minimization under constraints. The cost function includes terms corresponding to the deviation from the desired trajectory, magnitude of the control input, proximity to the obstacles and the final destination point, respectively. Information on obstacles can be incorporated online in the nonlinear model predictive framework and the resulting constrained optimization problem can be solved using nonlinear programming techniques such as augmented Lagrangian. Then kinematic constraints are treated by the Karush-Kuhn-Tucker (KKT) condition. This approach has been applied for generating safe trajectories for the nonlinear dynamics of a vehicle with a nonlinear tire model in a 2D polygonal environment. Simulation results show that the satisfactory performance was achieved in terms of short and safe trajectory satisfying input constraints.