• Physical Therapy Korea
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• v.15 no.4
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• pp.50-58
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• 2008

The purpose of this study was to investigate the effects of the task-oriented training according to the application time with the change of motor and cognition function. Focal ischemic brain injury was produced in Sprague-Dawley rats (20 rats, $250{\pm}50$ g) through middle cerebral artery occlusion (MCAo). Before MCAo induction, all rats were trained in treadmill training and Morris water maze training for 1 week. Then they were randomly divided into groups: Group I : MCAo induction ($n_1$=5), Grop II: the application for simple treadmill task training after. MCAo induction ($n_2$=5). Group III: the application for Morris water maze cognitive task training after MCAo induction ($n_3$=5). Group IV: the application for progressive treadmill task training and Morris water maze cognitive task training after MCAo induction ($n_4$=5). Modified limb placing tests (MLPTs) and motor tests (MTs) were performed to test motor function and then Morris water maze acquisition test (MWMAT) and Morris water maze retention test (MWMRT) were performed to test cognitive function. For MTs, there were significant interactions among the groups with the time (p<.001). Group IV showed the steeper increasing pattern than those in other Groups on the 7th and 14th day. For MLPTs, there were significant interactions among the groups with the time (p<.001). The scores in Group III. IV had showed the more decreasing pattern than those in Group I, II since the 7th day and 14th day. For MWMAT, there were significant interactions among the groups with the time (p<.001). Group II found the Quadrant circular platform showed the steeper decreasing pattern than that in Group I on the 9th, 10th, 11th and 12th day. Group III. IV found the quadrant circular platform showed the slower decreasing pattern than that in Group I, II, For MWMRT, there were significant differences among the four groups (p<.001). The time to dwell on quadrant circular platform in Group IV on the 13th day was the longest compared with other groups. These results suggested that the combined task training was very effective to improve the motor and cognition function for the rats affected on their focal ischemic brain injury.

• The Journal of the Acoustical Society of Korea
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• v.18 no.3E
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• pp.44-48
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• 1999

The CMOS four-quadrant analog multiplier for low-voltage low-power applications are presented in this thesis. The circuit approach is based on the characteristic of the LV (Low-Voltage) composite transistor which is one of the useful analog building block. SPICE simulations are carried out to examine the performances of the designed multiplier. Simulation results are obtained by 0.6㎛ CMOS parameters with 2V power supply. The basic configuration of the multiplier is the CMOS Gilbert cell with two LV composite transistors. The linear input range of the multiplier is over ±0.4V with a linearity error of less than 1.3%. The measured -3dB bandwidth is 288MHz and the power dissipation is 255 ㎼.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.453-454
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• 2016

The ESS(Energy Storage System) connected with distributed generation is drawing attention due to improving the quality load leveling, peak shaving for enhancing reliability of the power grid. The grid-connected inverter makes frequency adjustment to the active power's charge discharge according to the load variation. In addition, the inverter is possible to act as a reactive power compensation device to eliminate harmonic operates as power factor change inhibiting, anti-transient voltage fluctuation, active filter. In this paper, we propose a design method of igbt stack considering the reactive power supply capacity to improve the quality and reliability of the inverter. Moreover, the grid-connected inverter considering the four-quadrant rated operation designed stack and verified the feasibility of the design through a thermal analysis.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.141-142
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• 2013

본 논문에서는 단일 Quasi Z-소스 AC-AC 컨버터에 의한 4상한 출력 AC전압 제어를 제안하였다. 제안된 듀티비 제어방법을 통하여 한 대의 Quasi Z-소스 AC-AC 컨버터로도 동상의 벅-부스트 모드와 역상의 벅-부스트 모드를 모두 출력하는 4상한 출력 AC전압 제어를 하였다. 한 대의 Quasi Z-소스 AC-AC 컨버터만으로 종전의 듀티비 제어에 의해 동상의 부스트 모드와 역상의 벅-부스트 모드의 출력 전압이 발생되며, 제안한 듀티비 제어에 의해 동상의 벅 모드가 출력되는 4상한 출력 AC전압 제어법을 PSIM시뮬레이션에 의하여 입증하였다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.186-192
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• 1996

A modified learning rule is introduced for the implementation of feedforward artificial neural networks with on-chip learning circuitry using standard analog CMOS technology. Learning rule, is modified form the EBP (error back propagation) rule which is one of the well-known learning rules for the feedforward rtificial neural nets(FANNs). The employed MEBP ( modified EBP) rule is well - suited for the hardware implementation of FANNs with on-chip learning rule. As a ynapse circuit, a four-quadrant vector-product linear multiplier is employed, whose input/output signals are given with voltage units. Two $2{\times}2{\times}1$ FANNs are implemented with the learning circuitry. The implemented FANN circuits have been simulatied with learning test patterns using the PSPICE circuit simulator and their results show correct learning functions.

• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.155-160
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• 1999

이 연구는 도로상의 신호사거리에서 신호변환시 발생하는 혼돈지역의 개념을 이용하여 도로-철도 교차로에 설치되는 사각차단기의 운영시간을 결정하는 방법론을 제시한다. 이 방법론은 현재 미국 일리노이주에서 시카고-세인트루이스의 고속전철 노선중 6개의 교차로에 설치중인 사각차단기의 운영시간을 설정하여 제시함으로써 현장검증이 되었다. 특히, 운전자가 교차로 진입시 차단기 사이에 차량이 걸리지 않으며 혹은 정지시 안전하게 교차로 앞에서 정지하도록 하는 의사결정이 이루어 지도록 최적의 차단기 운영시간을 운전자에게 제시하였다.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.69-71
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• 2003

Switched reluctance machine has much attention because of high efficiency, high power and DC series torque characteristics with a traction drive. But the motor has to have a regenerative mode when it is adopted in an electric vehicle. A current divergence during the regeneration makes difficulties in the control of SRM. This paper proposes a reference current limitation strategy for a stable regeneration based on simulations and experimental tests. The motor is operated with conventional current limit and switching angle control method in motoring mode. Simulations and experiments are executed to verify proposed method.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.41-45
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• 2001

This paper presents an implementation of motion control system of Switched Reluctance Motor (SRM) using digital hysteresis controller by TMS320F240 DSP. SRM position control system possess several advantages over other motors, including high efficiency, simple structure, low cost, and four-quadrant operation at a wide speed range, especially for the servo drive systems with precision, stability and fast response characteristics in the industrial applications. In the suggested motion control system, position control using digital hysteresis controller is developed, and is evaluated using experimental testing. The developed system for cost reduction and high-performance by fully digital controller is shown a good response characteristic of motion control results.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.186-189
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• 2004

Switched reluctance machine has much attention because of high efficiency, high power and DC series torque characteristics with a traction drive. But the motor has to have a regenerative mode when it is adopted in an electric vehicle. A current divergence during the regeneration makes difficulties in the control of SRM. This paper proposes a reference current limitation strategy for a stable regeneration based on simulations and experimental tests. The motor is operated with conventional current limit and switching angle control method in motoring mode. Simulations and experiments are executed to verify proposed method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.8
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• pp.836-846
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• 1990

This paper presents a Static Var Compensator (SVC) system compensating the reactive power for power system, which consists of a voltage type Pulse Width Modulation (PWM) converter and a reactance linking the converter to the source. The system drives the four quadrant modes. The system determines the magnitude of the input voltage, and then compares it with the magnitude of the source voltage by regulating the phase of the SVC about the source. Therefore, the system generates leading compensation currents when the input voltage is larger than the source in magnitude, and lagging compensation currents for smaller input voltage. Reactive power about voluntary load in power system is smoothly compensated by those compensation currents, and also power factor of source is improved. Furthermore, the SVC system using PWM method may improve the source current waveforms by eliminating the 5th and 7th harmonic components from the input voltages.