• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.977-979
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• 2001

The application of SRM(Switched Reluctance Motor) is dramatically increasing due to a simple mechanical structure, high efficiency and a good high speed characteristics. Generally, turn-off angle of power switch must be limited the demagnetization period. To control high conduction ratio in motor operation and regenerative voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper proposes multi-level inverter to have a maximum conduction ratio of SRM. The proposed method is verified by experiment.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.19.2-19.2
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• 2011

ZnO nanowires have been fabricated by vapor-liquid-solidification with hot-walled pulsed laser deposition method. The diameter of ZnO nanowire has been systematically controlled simply by changing the thickness of Au catalyst. Field effect transistors with different diameter have been fabricated by using photolithography and e-beam lithography. The threshold voltage of ZnO nanowire FET showed enhanced mode and depleted mode depending on the diameter of ZnO nanowires. This is mainly due to the change of the carrier concentration depending on the size of nanowires. We have fabricated ZnO nanowire inverters using nanowire FETs. This simple method to fabricate ZnO nano-inverter will be useful to open the possibility of ZnO nanoelectronic applications.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.650-656
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• 2016

Voltage controlled oscillator (VCO) is widely used circuit component in high-performance microprocessors and modern communication systems as a frequency source. In present work, VCO designs using the different combination of NAND gates with three transistors and CMOS inverter are reported. Three, five and seven stages ring VCO circuits are designed. Coarse and fine tuning have been done using two different supply sources. The frequency with coarse tuning varies from 3.31 GHz to 5.60 GHz in three stages, 1.77 GHz to 3.26 GHz in five stages and 1.27 GHz to 2.32 GHz in seven stages VCO respectively. Moreover, for fine tuning frequency varies from 3.70 GHz to 3.94 GHz in three stages, 2.04 GHz to 2.18 GHz in five stages and 1.43 GHz to 1.58 GHz in seven stages VCO respectively. Results of power consumption and phase noise for the VCO circuits are also been reported. Results of proposed VCO circuits have been compared with previously reported circuits and present circuit approach show significant improvement.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.149-153
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• 2003

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 [W] prototype equipped with digital signal processor TMS320F241.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.91.3-91
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• 2002

This paper describes a design of an induction motor control system for industrial sewing machines. On the basis of vector control principle, the control system is simulated by using the ACSL, implemented on a DSP(TMS320C31).A space vector modulation is used as the inverter switching strategy. For the application of industrial sewing machines, A fast acceleration (deceleration) and removal of velocity ripples are required, because a sewing quality and sewing machines life time depends on these characteristics. The designed control system has fast dynamic characteristics and small speed vibration. The result is applied to the industrial sewing machine and result are shown.

• Solar Energy
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• v.18 no.1
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• pp.19-25
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• 1998

This paper describes a design method and characteristics analysis of the 3 kW grid-connected photovoltaic power generation system to establish the basic application technology of photovoltaic systems. The design specification of a 3 kW photovoltaic power generation system including a DC/AC inverter is suggested to investigate the system performance for grid connection. The results of the demonstration test from February to October show that the system with utilization rate up to 17% has reliable operation characteristics and is useful for peak-shaving of utility power.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.4
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• pp.701-707
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• 1987

This paper is concerned with an accurate delay time modling of the ED MOS logic gates and its application to the multiple delay logic simulator. The proposed delay model of the ED MOS logic gate takes account of the effects of not only the loading conditions but also the slope of the input waveform. Defining delay as the time spent by the current imbalance of the active inverter to charge and discharge the output load, with respect to physical reference levels, rise and fall model delay times are obtained in an explicit formulation, using optimally weighted imbalance currents at the end points of the voltage transition. A logic simulator which uses multiple rise/fall delays based on the model as decribed in the above has been developed. The new delay model and timing verification method are evaluated with repect to delay accuracy and execution time.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.626-629
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• 1997

The urban transit propelled by single sided linear induction motor(SLIM) have been in stage for practical application. Also, the use of the linear induction motor in traction systems enables large forces to be achieved without friction between wheels and rails. In this paper we discuss the linear induction motor (LIM) drive system (300KVA) for magnetic levitation vehicles.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.34-42
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• 2000

In this paper conventional technique will be described, which can be used for the measuring various parameters of induction motor. This is followed by presenting some other, alternative, techniques. The two tests are described which are suitable to obtain the electrical parameters of symmetrical 1hp three-phase squirrel-cage induction motor. These are the blocked rotor test and no load test. By the application of these, it is possible to determine the parameters which are presented in the steady-state equivalent-circuit of determining an induction motor. One conventional method of determining the inertia of an induction motors is obtained by performing retardation tests. The angular rotor speed of the motor is monitored, following its disconnection from the stator supply. Since the inertia torque J dw/dt contains the inertia coefficient J and the friction and windage torque Bw contains the coefficient B, then J and B can be determined by performing retardation tests.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.366-370
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• 1998

Indirect vector control for induction motors requires the use of observers for estimation or observation of rotor flux magnitude and position. In this paper, authors discribe the induction motor vector control and introduce a nonlinear observer, named ELO(extended Luenberger Observer), without simulation results as a preliminary work for trial application. Normally, design of nonlinear observer need coordinate transfromation and linearization through solving the partial different equation. However, ELO requires minimal solution of nonlinear partial differential equation. Simulation was performed by under the enviroment of Matlab and Simulink without the proposed observer because we are still working. Simulation was performed with conventional flux observer, a dc-ac inverter by SVPWM technique, a vector controller armed with multiple PI controllers