• Journal of Korean Neurosurgical Society
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• v.39 no.2
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• pp.130-135
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• 2006

Objective : After ischemic stroke, partial recovery of function frequently occurs and may depend on the plasticity of axonal connections. Here, we examine whether blockade of the Nogo/NogoReceptor[NgR] pathway might enhance axonal sprouting and thereby recovery after focal brain infarction. Methods : Adult male Sprague Dawley rats weighing $250{\sim}350g$ were used. Left middle cerebral artery occlusion[MCAO] was induced with a intraluminal filament. An osmotic mini pump [Alzet 2ML4, Alza Scientific Products, Palo Alto, CA] for the infusion of NgR-Ecto[310]-Fc to block Nogo/NgR pathway was implanted 1 week after cerebral ischemia. Prior to induction of ischemia, all animals received training in the staircase and rotarod test. Two weeks after biotin dextran amine injection, animals were perfused transcardially with PBS, followed by 4% paraformadehyde/PBS solution. Brain and cervical spinal cord were dissected. Eight coronal sections spaced at 1mm intervals throughout the forebrain of each animal with cresyl violet acetate for determination of infarction size. Images of each section were digitized and the infarct area per section was measured with image analysis software. Results : Histological examination at 11 weeks post-MCAO demonstrates reproducible stroke lesions and no significant difference in the size of the stroke between the NgR[310]Ecto-Fc protein treated group and the control group. Behavioral recovery is significantly better and more rapid in the NgR-Ecto[310]-Fe treated group. Blockade of NgR enhances axonal sprouting from the uninjured cerebral cortex and improves the return of motor task performance. Conclusion : Pharmacological interruption of NgR allows a greater degree of axonal plasticity in response this is associated with improved functional recovery of complicated motor tasks.

• Journal of Pharmacopuncture
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• v.21 no.4
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• pp.277-283
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• 2018

Objectives: Ethanol withdrawal following its chronic use is a serious outcome and challenging to treatment. The chronic use of ethanol induces a progressive neuroplasticity in different reigns of brain. In this study we evaluated the effects of aqueous extract of Crocus sativus L. (saffron) and its active compound, crocin, on the withdrawal behavior induced after repeated administration of ethanol, in two regimens of prophylactic (administration of drugs concomitant with the induction of dependence) and treatment (administration of drugs during the period of ethanol withdrawal) in mice which received ethanol. Methods: Ethanol dependence was induced by oral administration of 10% v/v ethanol (2 g/kg) for 7 days. The aqueous extracts of saffron (40, 80 and 160) and crocin (10, 20 and 40 mg/kg) were administered to mice in two regimens of prophylactic (along with ethanol) and treatment (during withdrawal period). Diazepam (1 mg/kg) was used as a positive control. Six hours after discontinuation of the ethanol, seizure was evaluated by the sub-convulsive dose of pentyleneltetrazole (PTZ) (30 mg/kg). The open field test and Rota rod test were used for evaluation of locomotor activity and motor incoordination, respectively. Results: Both extracts and crocin increased the number of crossed lined in the open field test. PTZ kindling seizure was inhibited in animals received extract (80 and 160 mg/kg) in both regimens. Motor incoordination was only improved following administration of crocin. Conclusion: The aqueous extract of saffron and crocin can be considered as safe agents and reliable alternative to diazepam in management of ethanol withdrawal syndrome.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.76-85
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• 2006

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass panels is proposed. This device can directly drive a glass panel and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic farces on the glass panel and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass panels is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass panel has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.574-585
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• 2015

This paper aims to improve the performance of conventional direct torque control (DTC) drives proposed by Takahashi by extending the idea for 5-level inverter. Hybrid cascaded H-bridge topology is used to achieve inverter voltage vector composed of 5-level of voltage. Although DTC is very popular for its simplicity but it suffers from some disadvantages like- high torque ripple and uncontrollable switching frequency. To compensate these shortcomings conventional DTC strategy is modified for five levels voltage source inverter (VSI). Multilevel hysteresis controller for both flux and torque is used. Optimal voltage vector selection from precise lookup table utilizing 12 sector, 9 torque level and 4 flux level is proposed to improve DTC performance. These voltage references are produced utilizing a hybrid cascaded H-bridge multilevel inverter, where inverter each phase can be realized using multiple dc source. Fuel cells, car batteries or ultra-capacitor are normally the choice of required dc source. Simulation results shows that the DTC drive performance is considerably improved in terms of lower torque and flux ripple and less THD. These have been experimentally evaluated and compared with the basic DTC developed by Takahashi.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.15-24
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• 2011

Modeling and simulation for Green Energy depends largely on the type of system under investigation. The topics are very wide ranging from semiconductor physics (solar), electrical motor/generator (wind turbines), power electronics (grid connections) to typical control strategies. To correctly model these technologies requires a broad set of models and various simulation techniques. To further refine or detail the simulation the modeling has to be performed on a specific level, being system, circuit or component level. Combinations of several levels allows gradually improving the validity of the overall model against available parameters and model equations.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.794-796
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• 1999

본 논문에서는 3상 유도전동기의 속도를 제어하는데 기존 제어기의 문제점을 해결하고 최적화하기 위해서 유전자 알고리즘을 이용한 하이브리드 퍼지 -PID(HFPID) 제어기를 고안하고, 이에 대한 파라미터 설정 방법을 제안한다. 유도전동기의 제어는 지연시간이 길고, 비선형성이 강하며, 부하변동이 잦은 프로세스이기 때문에, 기존의 제어방식으로는 만족할만한 결과를 얻을 수 없다. 제안한 하이브리드 퍼지-PID 제어기는 PID 제어기의 장점인 과도기의 우수성과 퍼지 제어기의 장점인 정상기의 우수성을 퍼지 변수로 결합시켜 설계한다. 이 제어기에 유전자 알고리즘을 적용하여 최적의 퍼지 및 PID 파라미터를 설정하다. 그리고 이 제어기를 3상 유도전동기의 속도 제어에 응용한다. 또한 속도오차에 대한 룩업 표를 만들어 온라인 실시간 제어를 가능하게 한다. 이상의 과정을 3상 유도전동기에서 컴퓨터 시뮬레이션 하였다. 시뮬레이션 결과를 비교해 볼 때, 하이브리드 퍼지-PID 제어기는 기존의 제어기 보다 전동기의 속도 및 토크성분 전류 둥의 특성에서 우수한 성능을 보였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.5
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• pp.60-70
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• 1989

In this paper, a new HTF(Harmonic torque function) which takes into account the phasor of harmonic current, and which represents torque ripple content of induction motor is proposed. Through experiments and computer simulations using direct-quadrature two axis model, the proposed HTF is proved to be valid. Applying this function, six-step, SPWM and TPWM pulse-amplitude-width-controlled inverters are evaluated and compared with each other. A good control strategy for PAWM inverters was chosen from the results. It turns out that TPWM is superior to SPWM in torqur ripple content and output voltage amplitude of fundamental wave and six-step is better than PWM when CR is 9.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1057-1058
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• 2008

철도차량용 선형추진시스템에 있어서, 지상레일에 설치되는 선형유도전동기의 2차측의 리액션플레이트의 시공 공차에 의해서 발생되는 1차측과의 공극의 변화는 추진 시스템의 운행 시 승차감과 기기효율을 떨어뜨리는 결과를 초래하기 때문에 선형유도전동기의 균일 공극 운전은 추진 시스템의 효율을 증가시킬 수 있는 중요한 사항이다. 또한 경사구간에서의 선형유도전동기의 공극길이 조절을 통해서 선형유도 전동기의 용량 변경 없이 추력을 증가시키는 것이 가능하다. 따라서 본 논문에서는 선형유도전동기의 공극 길이를 제어할 수 있으며, 공극 길이제어를 통하여 추진 시스템의 성능 변화를 살펴볼 수 있는 축소 모델선형유도전동기 성능시험기의 공극조절 시스템의 동적 모델링 및 특성 해석을 통하여 시스템을 구성하는 파라미터들의 특성 변화 분석 및 시스템 구현 가능성에 대한 연구를 수행하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.131-139
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• 2000

일반적으로 시스템 인식과 제어에 이용하는 다층 신경회로망은 기존의 역전파 알고리즘을 이용한다. 그러나 결선강도에 대한 오차의 기울기를 구하는 방법이기 때문에 국부적 최소점에 빠지기 쉽고, 수렴속도가 매우 늦으며 초기 결선강도 값들이나 학습계수에 민감하게 반응한다. 이와 같은 단점을 개선하기 위하여 확장된 칼만 필터링 기법을 역전파 알고리즘에 결합하였으나 계산상의 복잡성 때문에 망의 크기가 증가하면 실제 적용할 수 없다. 최근 신경회로망을 선형과 비선형 구간으로 구분하고 칼만 필터링 기법을 도입하여 수렴속도를 빠르게 하고 초기 결선강도 값에 크게 영향을 받지 않도록 개선하였으나, 여전히 은닉층의 선형 오차값을 역전파 알고리즘에 의해서 계산하기 때문에 학습계수에 민감하다는 단점이 있다. 본 논문에서는 위에서 언급한 기존의 신경회로망 알고리즘의 문제점을 개선하기 위하여 은닉층의 목표값을 최적기법에 의하여 직접계산하고 각각의 결선강도 값은 반복최소 자승법으로 온라인 학습하는 알고리즘을 제안하고 이들 신경회로망 알고리즘과 비교하고자 한다. 여러 가지 시뮬레이션과 실험을 통하여 제안된 방법이 초기 결선강도에 크게 영향을 받지 않으며, 기존의 학습계수 선정에 따른 문제점을 해결함으로써 신경회로망 모델에 기초한 실시간 제어기 설계에 응용할 수 있도록 하였다. 또한, 유도전동기의 속도추정과 제어에 적용하여 좋은 결과를 보였다.