• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.583-585
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• 2002

In this paper. the characteristics of a linear induction motor with the moving cage-type secondary are analyzed using finite element method. Thus thrust. normal force and the secondary bar currents distribution are obtained for different positions of the moving secondary.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.335-340
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• 2004

Recently, multilevel H-bridge inverters have become more popular in medium to high power ac drive applications. One of significant advantages of them is low harmonic contents in their input line currents thanks to the transformer with multiple phase-shifted secondary windings. This paper attempts to provide basic guidelines for the design of the phase shifting transformer windings and theoretical analysis of input line current harmonics.

• Journal of Power Electronics
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• v.3 no.2
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• pp.124-138
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• 2003

An advanced simulation model for brushless dc (BLDC) motor drives using Matlab is presented. In the developed model, the dynamic characteristics of speed and torque as well as voltages and currents of pwm inverter components can be effectively monitored and analyzed. Therefore, it can be expected that the developed simulation model can be an easy-to-design tool for the development of BLDC motor drives including control algorithms and topological variations with reduced computation time and memory size.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.158.4-158
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• 2001

This paper presents a novel circuit configuration for realizing the continuous-time active-only voltage-mode integrator. The proposed integrator consists only of internally compensated type operational amplifier (OA) and operational transconductance amplifiers (OTAs). Since no external passive elements are required, the integrator is suitable for integrated circuit implementation in either bipolar or CMOS technologies. Moreover, the integrator gain can be electronically tuned by adjusting the bias currents of the OTAs. The characteristics of the proposed integrator and the effectiveness of the design procedure in realizing various analog transfer functions have been examined by PSPICE simulation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.1
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• pp.49-58
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• 1998

In this paper, a new equivalent circuit model for quantum-well laser diode (LD) is proposed. The model includes carrier transport effects in the SCH region, and rprovides, in a stable and accurate manner, large-and small-signal responses of laser diode output power as function of injected currents. SPICE simulation was performed using the circuit model and results are presented for L-I characteristics, pulse and frequency responses under various conditions. It is expencted that the new equaivalent circuit model will find useful applications for designing and analyzing OEIC, LD driver circuits, and LD packaging.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.659-662
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• 1999

As utility pollution take a growing interest, ac/dc converter optimizing utility condition has been vigorously studied in decades. In this paper three phase DCM converter is analyzed and equations for average input currents are presented. Also relationships of voltage gain & duty according to angular velocity are presented and variable frequency controller is implemented using reset integrator which is designed in detail. In result power factor and THD characteristics of 3-stage and 4-stage operation ae compared respectively.

• Journal of Magnetics
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• v.21 no.3
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• pp.322-329
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• 2016

In this paper, we propose an array sensing detection method for smelting of submerged arc furnaces (SAF) based on electromagnetic radiation. AC magnetic field generated by electrode currents and molten currents in the furnace is reflected outside of the furnace. According to the spatial distribution of electromagnetic field a radiation model of SAF is built. We design a 3D magnetic field sensing array system in order to collect the magnetic field information. Through the collected information, the current distribution characteristics of SAF are described and the key parameters of smelting are obtained. Theoretical simulation and field test show that the curves acquired by the sensing array can accurately reflect the information of the relative displacement when the relative displacement between the array and electrode is 10 cm. Compared with the detection method of 3D single point, the proposed array sensing method of magnetic field obtains better results in terms of real-time and accuracy, and has good practical value for industrial measurement.

• Journal of Navigation and Port Research
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• v.34 no.9
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• pp.711-718
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• 2010

Redevelopment of the domestic small fishing ports is being started in earnest by applying the environmentally friendly technology in order to attract tourists. For the purpose of improving water quality in the harbor, selection of breakwater type might have the priority to secure calmness and stability. Therefore, this study is to determine the hydraulic characteristics of reflective ratio, installation efficiency and stability of the special type of blocks through the hydraulic model experiment. The results were introduced to analyze for the effect of infield construction work through numerical analysis. Gujora, a small fishing port in southern Korea, is affected by the waves of SSE, S, SSW direction and strong tidal currents. The results of applying cylindrical slit block show that stability of the blocks and harbor calmness were secured. Considering that the pass rate of a long period wave is still excellent, the primary objective of wave control and the secondary objective of improving water exchange are satisfied simultaneously.

• 전기의세계
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• v.18 no.6
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• pp.9-22
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• 1969

This thesis has suggested a method of applying the Maximum Principle of Pontryagin to the optimal control of distributive electrical networks. In general, electrical networks consist of branches, nodes, sources and loads. The effective values of steady state currents and voltages are independent of time but only expressed as the functions of position. Moreover, most of the node voltages and branch currents are not predetermined, that is, initially unknown, and their inherent loop characteristics satisfy only Kirchhoff's current and voltage laws. The Maximum Principle, however, needs the initial fixed values of all state variables for its standand way of application. In spite of this inconsistency this thesis has undertaken to suggest a new approach to the successful solution of the above mentioned networks by introducing scaling factors and a state variable change technique which transform the boundary-value unknown problem into the boundary-value partially fixed and partially free problem. For the examples of applying the method suggested, the control problems for minimizing copper quantity in a distribution line have been solved with voltage drop constraint imposed on. In the case of uniform load distribution it has been shown that the optimal wire diameter of the distribution line is reciprocally proportional to the root of distance. For the same load pattern as above the wire diameter giving the minimum copper loss in the distribution line has been shown to be reciprocally proportional to distance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.822-829
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• 2002

This paper deals with the distribution characteristics of the current density and axial magnetic flux density for each slits made on the contact electrode in the vacuum interrupter with axial magnetic field type using 3-dimension finite element analysis. It has been known that the presence of an axial magnetic field parallel to the current flow in the arc plasma can increase the high current breaking capacity of vacuum interrupter by carrying out the arc plasma from constricted mode to diffusion mode. The axial magnetic field is created of itself by current flow in the segments of coil electrode behind the contact electrode. The analyzed results show that if the slits are made in the contact electrode, they can increase the current density and axial magnetic flux density in the contact electrode surface and at the gap distance, which is due to decrease the effect of eddy currents flowing in the contact electrode. The phase shift due to eddy currents, defined 3s time difference between the maximum value of current and axial magnetic field, is decreased still more by increasing the number of slits made in the contact electrode at the center point of gap distance. These results demonstrate that 3-dimension finite element analysis has a great deal of merits in the development and evaluation of new electrode at the design of vacuum interrupter.