• Journal of Power Electronics
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• v.11 no.4
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• pp.606-611
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• 2011

Power electronics is a key technology for electric, hybrid, plug-in hybrid, and fuel cell vehicles. Typical power electronics converters used in electric drive vehicles include dc/dc converters, inverters, and battery chargers. New semiconductor materials such as silicon carbide (SiC) and novel topologies such as the Z-source inverter (ZSI) have a great deal of potential to improve the overall performance of these vehicles. In this paper, a Z-source inverter for fuel cell vehicle application is examined under three different scenarios. 1. a ZSI with Si IGBT modules, 2. a ZSI with hybrid modules, Si IGBTs/SiC Schottky diodes, and 3. a ZSI with SiC MOSFETs/SiC Schottky diodes. Then, a comparison of the three scenarios is conducted. Conduction loss, switching loss, reverse recovery loss, and efficiency are considered for comparison. A conclusion is drawn that the SiC devices can improve the inverter and inverter-motor efficiency, and reduce the system size and cost due to the low loss properties of SiC devices. A comparison between a ZSI and traditional PWM inverters with SiC devices is also presented in this paper. Based on this comparison, the Z-source inverter produces the highest efficiency.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.9-13
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• 1997

The present study was designed to develop the functional electrical stimulation system in order to restore motor function of paralytic patients. We attempt to establish adequate stimulus parameters for the recovery of work unction in lower limb paralysis patients and to develop the electrical stimulation system, which is effective to protect foot drop in these patients. In our animal and human experiment, adequate stimulus condition for surface electrode on the lower limb were 0.2-0.3ms at the duration and 50 Hz, which contain 600Hz train pulse. This parameter has efficiently prevented the foot drop from lower limb paralysis, decreased muscle fatigue and induced powerful contraction of lower limb muscle.

• Archives of Plastic Surgery
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• v.36 no.2
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• pp.194-199
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• 2009

Purpose: The orbital fat buldging may cause irregular contour of lower eyelid, which is not youthful appearance. The conventional method of fat excision may cause the eyeball to move backward and downward, making enopthalmia is inevitable. The transcutaneous approach to reach the orbital septum can increase the risks of scleral show resulting from scarification at the level of the septum orbicularis junction and damaging the vertical motor branches of the preseptal orbicularis oculi muscle of the lower eyelid. Method: From July 2007 to March 2008, total of 21 patients underwent transconjunctival capsulopapebral fascia fixation procedure. In 8 patients, the herniated fat pad of the lower eyelid was relocated back into the orbit without external skin excision using capsulopalpebral fascia fixation. But in 13 patients, excision of redundant skin of the lower eyelid was performed using pinching technique, not involving orbicularis oculi muslce. In 5 patients, lateral canthotomy was done bilaterally for good visual field. In 6 patients, lateral canthopexy was also combined to correct loosening of lower eyelid. Results: Most of the patients were satisfied after at least 5 months of follow up. No patient showed scleral show. But 2 patients complained of undercorrection slightly, without secondary operation in 1 patient and re - capsulopalpebral fascia fixtation through transconjunctival approach in another patient. Conclusion: Orbital fat repositioning using transconjunctival capsulopalpebral fascia fixation is a good procedure to show youthful appearance without increasing the risk of scleral show and also showed fast recovery compared to the conventional transcutaneous approach.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.112-117
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• 2015

Purpose: The purpose of this study was to examine the effects of a task-specific obstacle crossing rehabilitation program on functional gait ability in patients with cerebellar ataxia. Overall, we sought to provide ataxia-specific locomotor rehabilitation guidelines for use in clinical practice based on quantitative evidence using relevant analysis of gait kinematics including valid clinical tests. Methods: Patients with cerebellar disease (n=13) participated in obstacle crossing training focusing on maintenance of dynamic balance and posture, stable transferring of body weight, and production of coordinated limb movements for 8 weeks, 2 times per week, 90 minutes per session. Throughout the training of body weight transfer, the instructions emphasized conscious perception and control of the center of body stability, trunk and limb alignment, and stepping kinematics during the practice of each walking phase. Results: According to the results, compared with pre-training data, foot clearance, pre-&post-obstacle distance, delay time, and total obstacle crossing time were increased after intervention. In addition, body COM measures indicated that body sway and movement variability, therefore posture stability during obstacle crossing, showed improvement after training. Based on these results, body sway was reduced and stepping pattern became more consistent during obstacle crossing gait after participation in patients with cerebellar ataxia. Conclusion: Findings of this study suggest that task-relevant obstacle crossing training may have a beneficial effect on recovery of functional gait ability in patients with cerebellar disease.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.435-442
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• 2003

In this paper, biomechanical aspects of dynamic대학교postural responses against forward perturbations were experimentally determined simultaneous measurements of joint angles, accelerations. EMG activations, center of pressure(CoP) movements and ground reaction forces(GRF), Thirteen young healthy volunteers, stood on a flat platform, were translated into the forward direction by an AC servo-motor at two separate velocities(0.1m and 0.2m/s). In order to recover postural balance against the forward perturbation, joint motions were observed in the sequence of the ankle dorsiflexion, the knee flexion and then the hip flexion during the later acceleration phase. Both acceleration patterns at the heel and the sacrum were shown the forward acceleration pattern during the later acceleration phase and early of constant velocity phase as increasing platform velocity, respectively. Tibialis anterior(TA) for the ankle dorsiflexion and biceps femoris(BF) for the knee flexion. the primary muscle to recover the forward perturbation, was activated during the half of acceleration phase. Ankle strategy was used for slow-velocity perturbation, but mixed strategy of both ankle and hip used for the fast-velocity perturbation. In addition, parameters of perturbation such as timing and magnitude influenced the postural response against the perturbation.

• Archives of Reconstructive Microsurgery
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• v.13 no.1
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• pp.68-73
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• 2004

Transverse rectus abdominis muscle (TRAM) free flap is widely used for breast reconstruction, however donor-site morbidities such as abdominal wall weakness, hernia, bulging are troublesome. For the purpose of minimizing donor-site morbidity, there has been a surge in interests in muscle sparing free TRAM flap preserving the anatomy of rectus abdominis muscle, fascia, and motor nerve. The purpose of this study is to investigate complication and morbidity after muscle sparing free TRAM flap. Between August, 1995 and May, 2003, there were 108 cases of muscle sparing free TRAM flap of breast reconstruction. There was no abdominal hernia. There were 4 cases of dog ear, 3 cases of marginal necrosis of apron flap, 2 cases of asymmetry of umbilicus. At 1 year after operation, most patients feel comfortness in physical exercise. Muscle sparing free TRAM flap provides ample amount of well vascularized soft tissue with small inclusion of rectus abdominis muscle and fascia. Also it minimizes donor-site morbidity with rapid recovery of abdominal strength.

• Journal of Korean Neurosurgical Society
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• v.47 no.1
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• pp.55-57
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• 2010

Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine is rare, even in the Far East. A 45-year-old female presented with a 4month history of progressive motor weakness in the lower extremities, numbness below the midthoracic area, and spastic gait disturbance. Neuroradiological examinations revealed massive OPLLs at the T4-T6 levels with severe anterior compression of the spinal cord. Anterior decompressive corpectomies with bone grafts were performed from T4 to T6 using a trans-thoracic approach. After surgery, the patient made an uneventful recovery. However, eleven years after surgery, the patient developed recurrent lower extremity weakness and spastic gait disturbance. De novo OPLLs at the C6-T2 levels were responsible for the severe spinal cord compression on this occasion. After second surgery, paralysis in both legs was resolved. We present a rare case of late cervicothoracic OPLL in a patient surgically treated for thoracic OPLL.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.289-299
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• 1998

In this present study, we investigated the effects of red ginseng extract and its active constituents - Rbl , Re, Rgl on cycloheximide (CXM)-induced amnesia in the passive avoidance task in rats. Red ginseng water extract at 0.05-0.5 g/kg could improve CXM-induced amnesia in rats, Furthermore, the recovery effect of Rbl at 10 mghg administered 30 min before training trial from CXM-induced amnesia was better than those of Rbl administered other time before or after training trial. Rbl at 0.001-0.1 mghg could significantly improve CXM-induced amnesia and at 1 mghg completely augmented, but at 10 mghg its improving effect slightly weakened. Rgl and Re at 0.3-10 mghg could significantly improve CXM-induced amnesia and Rgl at 10 mg/kg completely avgmented. On the other hand, Rbl at 10 mghg could prolong the step through latencies in the training trial. These results suggest the beneficial effect of red ginseng extract on CXM-induced amnesia in rats could mainly due to the contribution of its active constituents - Rbl, Re, Rgl. The improving effect of Rbl on CXM-induced amnesia was best among the three active constituents. But the reduction in the improving effect of Rbl at 10 mg/kg might be due to the decrease in motor activity and attention to the passive avoidance task.

• Speech Sciences
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• v.12 no.4
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• pp.247-254
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• 2005

This study aimed at clarifing clinical effects of eight-step continuum treatment in a patient who showed apraxia of speech after stroke. The eight-step continuum treatment consisted of 8 steps and its clinical efficacy has been proven with American apraxic patients. However, it has not been clinically proven to be effective in Korean patients with apraxia of speech as of yet. Therefore, this study was conducted in an effort to provide preliminary clinical evidence regarding its effectiveness regardless of the linguistic differences between Korean and English. The therapy took place twice a week for 6 months, a total of 48 times. The results showed that the patient's receptive language was improved from 83% to 89% and 37% in accuracy, and expressive language from 15% to 37%. It seemed that spontaneous recovery did not playa role in his improvement since the study was conducted 2 years after the stroke. In addition, the improvement of expressive language was much greater(22%) than that of receptive language(6%), which implied that the therapy was effective in apraxia of speech because apraxia of speech is relatively confined to expressive ability, more specifically motor programming and sequencing.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.364-371
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• 2005

Fuel cell systems(FCS) have a financial and environmental advantage by providing electricity at a high efficiency and useful heat. For use in a residence, a polymer electrolyte fuel cell system(PEFCS) with a battery pack and a hot water storage tank has been modelled and simulated. The system is operated without connection to grid line. Its electric conversion efficiency and heat recovery performance are highly dependent on operation strategies and also on the seasonal thermal and electric load pattern. The output of the fuel cell is controlled stepwise as a function of the state of the battery and/or the storage water tank. In this study various operation strategies for cogeneration fuel cell systems are investigated. Average fuel saving rates at different seasons are calculated to find proper load management strategy. The scheme can be used to determine the optimal operating strategies of PEFCS for residential and building applications.