• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.25-29
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• 2001

Objective : Intracranial metastasis is responsible for nearly 50% of mortalities of systemic cancers. Although its frequency is increasing and there is little doubt that improving the quality and expectancy of life is the final goal, the mode of treatment is still disputed. The authors report the postoperative motor function after surgery in patients with metastatic tumors around the motor cortex. Materials and Methods : We studied 24 patients with metastatic tumors around the central sulcus during the last 22 months. Motor function was assessed pre- and post-operatively as well as its response to corticosteroids. MRI, neuronavigation system and intraoperative ultrasonography were used for tumor localization and functional MRI and cortical stimulator were used to define the motor cortex. Results : Single metastasis was found in 13 cases(54%) and 11 cases(44%) had multiple foci. Thirteen cases were located in precentral, 7 in postcentral, and 4 in superior or middle-frontal lobe. The most common primary focus was the lung(16 cases). There was no difference in postoperative motor function improvement between the steroid responsive group and non-responsive group(92% versus 90%). Ninty-two percent of the patients showed significant improvement of motor function and lived independently but there was worsening in the upper extremity in one and in another no improvement. Whole brain radiation of 3000cGy was given in all cases and 4 patients died of recurrence in primary or intracranial focus during mean follow-up periods of 14 monthes. Conclusion : Surgery may provide substantial improvement of the motor function and quality of life of the patients with metastatic tumors around the motor cortex.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1051-1052
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• 2011

This paper deals with optimum design criteria to minimize the torque ripple of a concentrated winding Synchronous Reluctance Motor(SynRM) using Response Surface Methodology(RSM). The feasibility of using RSM with the finite element method(FEM) in practical engineering problem is investigated with omputational examples and comparison between the fitted response and the results obtained from an analytical solution according to the design variables of stator and rotor in concentrated winding SynRM(6slot). The focus of this paper is the efficiency evaluation on the basis of load condition in a Concentrated Winding Synchronous Reluctance Motor and distributed Winding Synchronous Reluctance Motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2103-2108
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• 2007

This study investigates the dynamic characteristics of Synchronous Reluctance Motor (SynRM), with segmental rotor structure, using finite element method in which the moving mesh technique is considered. The focus of this paper is the efficiency of on-line parameter identification system for position sensorless control of a SynRM considering saturation and iron loss. Comparisons are given with angle of the observer and those of proposed FEM & Preisach model of synchronous reluctance motor, respectively. The position sensorless control using identified motor parameters is realized, and the efficiency of the on-line parameter identification system is verified by experimental results.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.36-38
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• 2005

In home appliances, electric energy is optimally controlled by using power electronics technology, creating a comfortable environment in terms of energy saving, low sound generation, and reduced time consumption. Usually simplicity and robustness make the three phase induction motor attractive for use in domestic appliance, including washing machines. Two main types of domestic washing machine have evolved. We focus on the front loading machine favored in Europe, which has a horizontal drum axis. The efficiency improvement in home appliances is very important for customers. Induction motor efficiency can be improved by means of loss reduction, which can be realized by motor selection and design, improvement of the waveforms supplied by power Inverter, utilizing a suitable control method. So this paper describes the architecture and feature of washing machine fed induction motor drive under minimizing losses vector control.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1001-1002
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• 2007

This study investigates the dynamic characteristics of Synchronous Reluctance Motor (SynRM), with segmental rotor structure, using finite element method in which the moving mesh technique is considered. The focus of this paper is the efficiency of on-line parameter identification system for position sensorless control of a SynRM under saturation and iron loss. Comparisons are given with angle of the observer and those of proposed FEM & Preisach model of synchronous reluctance motor, respectively. The position sensorless control using identified motor parameters is realized, and the effective of the on-line parameter identification system is verified by experimental results.

• The Journal of Korean Physical Therapy
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• v.20 no.3
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• pp.1-7
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• 2008

Purpose: Implicit motor learning is the capacity to acquire skill through physical practice without conscious awareness of what elements of performance improved. This study investigated whether subacute stroke patients can implicitly learn a perceptual-motor task. Methods: We recruited 12 patients with subacute stroke and 12 age-matched controls. All participants performed a perceptual-motor task that involved pressing a button corresponding with colored circles (blue, green, yellow, red) on a computer screen. The task consists of 7 blocks composed of 10 repetitions for a repeating 12-element sequence (total 120 responses). Results: Both groups demonstrated significant improvement in acquisition performance. Reaction times deceased in both groups at similar rate within the sequential block trials (2-5 blocks), and reaction times increased at a similar rate when the task paradigm was transferred from the sequential block trial to the random block trial (5-6-7 blocks). Conclusion: The results of this study suggest that patients with sub-actue stroke can implicitly learn a perceptual motor skill. Although explicit instructions should be used to focus the learner's attention rather than provide information about the task, the application of implicit motor learning strategies in the rehabilitation setting may be beneficial.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.1
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• pp.1-10
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• 2015

Purpose: This study investigated the relationships of handwriting legibility and perceptual-motor skills, and handwriting speed and perceptual-motor skills. And identified the predictors that most affect the handwriting of preschool children. Methods: Twenty-three typically developing preschool aged children (mean age: 68.61 months, SD=2.04) were selected through the Korean-Denver Developmental Screening Test-2(K-DDST-2). The children were tested with regard to handwriting legibility, visual perception, visual-motor integration and fine-motor coordination. Results: First, a significant relationship was not found among handwriting legibility, visual perception, visual-motor integration and fine-motor coordination. Second, a significant relationship was found among handwriting speed, visual perception and fine-motor coordination. Third, stepwise multiple regression analyses showed that general visual perception were significant predictors for handwriting speed. Conclusion: Occupational therapists should evaluate children's visual perception levels utilizing a standardized test, and focus on general visual perception in order to improve handwriting skill(speed). Also, occupational therapists are expected to play an important role in the management and treatment of children's handwriting skills.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.338-343
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• 2010

Low cost motor drives are being sought for high volume energy efficient home appliances. Key to the realization of such low cost motor drives is to reduce the power electronic converter in terms of its components, particularly the active devices, finding the motor with least complexity for manufacturing and a controller that could extract the desired performance from the machine and converter combination. These and other factors such as self-starting, speed control over a wide range and most of all the crowning aspect of a four quadrant operation with bare minimum number of controllable switch (or switches) remain as formidable challenges for low cost motor drive realization. In this paper, a four quadrant switched reluctance motor (SRM) drive with only one controllable switch is realized by using a two-phase machine. The theory and operation of the proposed four-quadrant SRM drive with the proposed control algorithm for its realization are described. The motor drive is modeled, simulated and analyzed to verify its feasibility for self-starting, speed control and for four quadrant operation and the simulation results are presented. Experimental results confirm the validity of the proposed control algorithm for four quadrant control of the SRM drive. The focus of the paper is mainly directed toward the control algorithm for realizing the four-quadrant operation of the two-phase SRM drive with a single controllable switch converter.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.85-87
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• 2009

Linear motor is an energy conversion device which makes kinetic energy from electrical energy. This paper presents a method to reduce torque ripples by variation of the current. The torque ripples are basically caused by detent force so this method has a focus on reducing detent force. The torque ripples were calculated by finite element method.

• Journal of Computing Science and Engineering
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• v.7 no.2
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• pp.139-146
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• 2013

Recent advances in computer science enabled people with severe motor disabilities to use brain-computer interfaces (BCI) for communication, control, and even to restore their motor disabilities. This paper reviews the most recent works of BCI in stroke rehabilitation with a focus on methodology that reported on data collected from stroke patients and clinical studies that reported on the motor improvements of stroke patients. Both types of studies are important as the former advances the technology of BCI for stroke, and the latter demonstrates the clinical efficacy of BCI in stroke. Finally some challenges are discussed.