• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.373-375
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• 2004

The SRM is more robust and lower cost than other type motors. The inverter for SRM cannot have shoot through fault, since a phase winding of SRM is independent of other phase windings. The SRM has high starting torque and high power density. But it has torque ripples due to nonlinear magnetic characteristics. Therefore, SRM has highly non-linear torque producing characteristics. Because fuzzy logic is a flexible and general-purposed method for implementing non-linear dynamic functions, it is effective for the control of high current SRM. We design the fuzzy controller and demonstrate the fuzzy control system by MATLAB.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.37-40
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• 2001

This paper is suggested an optimal switching angle of a switched reluctance motor drive system for maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed As results, it improves the efficiency about 2[$\%$]. And a torque ripple is also reduced compared with that of the conventional switching angle magnetizing approach. In order to start softly regardless of a large ripple torque, the profile of phase current is predicted and current control mode was adapted when it is operated under the starting speed.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.46-48
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• 2004

Recently, the study of sensorless drive of IPMSM is coming to be active. In sensorless drive, because the wrong estimation of the initial rotor position brings about the decrease of the starting torque, or a temporary reverse revolution, it is important to know the exact importation of the initial rotor position. In this paper, the initial rotor position estimation method is based on the current peak measured by applying the pulsewise voltage and the current peak is changed according to the rotor position owing to the saliency of the rotor. The effectiveness of the proposed algorithm is verified by the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1261-1267
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• 2007

Although LEDs have been used in various applications with improving the brightness and luminous efficacy, the electrical and optical characteristics of high power LED varies at different temperature and starting time. In this paper, optimal heat sink and apparatus design were conducted using IR camera and ICEPAK on the LED bulb consisting with fourteen LED array. The temperatures of heat sink and LED device of the designed LED bulb without cooling pan were $74^{\circ}C\;and\;96.8^{\circ}C$, respectively, showing in good themal characteristics. For high efficiency driving circuit of LED array adopted optimal heat sink design, driving circuits of constant voltage and current circuits were suggested and fabricated. As a result the efficacy of all driving circuits showed more than 20 lm/W. Also, the constant current circuits are suitable for signal lamp, hallway lamp, and flash lamp having short operating time(about 30 min). On the other hand, a reading light and indoor lamp having long operating time can be controlled by constant voltage circuit.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.224-227
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• 2004

The goal of this paper is optimal switching angle of switched reluctance motor drive system for maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed. As results, it improved the efficiency about $2[\%]$. And a torque ripple is also sufficiently reduced compared with that of the conventional switching angle magnetizing approach. In order to start softly regardless of a large ripple torque, the profile of phase current is predicted by the ANFIS, and current control mode was adapted when it is operated under the starting speed. Variable implementations on the fields will guarantee the more practical drive system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.8
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• pp.820-827
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• 1990

For the purpose of investigation the thrust force, the lateral force, and the eddy current loss when the primary and the secondary of a single-sided linear induction motor is displaced in the space, this paper proposes an analysis technique for the characteristics of the eddy current induced on the secondary and the magnetic flux density distribution in the y-z plane by F.E.M. To verify the effectiveness of this analysis technique, the starting-thrust force due to a lateral displacement is compared to the experimental data.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.4
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• pp.165-173
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• 2002

The goal of this paper is optimal switching angle of switched reluctance motor drive system fur maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed. As the results, it improved the efficiency about 2[%]. And a torque ripple is also sufficiently reduced compared with that of the conventional approach. In order tn start softly regardless of large ripple torque, the profile of phase current is predicted by the ANFIS, and current control mode was adapted when it is operated under the starting speed. Variable implementations en the fields will guarantee the more practical drive system.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.57.1-57.1
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• 2017

As an upgrade we report the current ASTE ultra-wideband corrugated horn design. The length of the feedhorn gets shortened from 12.5 mm to 11 mm, and it shows better side lobe level at the far-field patterns compared with the previous design. We looked into possible quasi-optical solution to match the feedhorn beam to the optics of the current ASTE telescope, starting from frequency-independent solution using two ellipsoidal mirrors to which wideband performance of the feedhorn naturally fits. We used a commercial physical optics package (GRASP) with an user-defined optimizer to give physical constraints to evaluated optical designs for highest efficiency.

• Progress in Superconductivity and Cryogenics
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• v.2 no.2
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• pp.44-48
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• 2000

The high temperature superconducting bulk can be used as the rotor of an ac motor. This paper presents the fabrication and test results of a ac motor with HTS bulk rotor. The rotor of a conventional squirrel cage induction motor was replaced with cylinder type YBCO bulk. Height and outer diameter of the HTS bulk was 15mm and 46mm, respectively. Eddy current brake using aluminium disk was used to measure the torque of the HTS motor. No load test, locked rotor test and load test were performed to examine the characteristics of the HTS motor. Test results show the motor can rotate at synchronous speed without any special starting circuit. Maximum output power of the constructed HTS motor was 408W.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.91-94
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• 2000

We fabricated resistive super- conducting fault current limiters (SFCL) based on YBCO thin films grown on 2" diameter $Al_{2}O_{3}$ substrates. Two SFCLs with nearly identical properties. two SFCLs with nearly identical properties were connected in series to investigate simultaneous quenching. There was a difference of several half cycles in their quench starting time, although the difference was not more than 0.1 msec when they were operated separately. This imbalance was removed by connecting a shunt resistor to an SFCL in parallel. Increased power input at high voltages also reduced the initial imbalance in power dissipation. Further efforts on the simultaneous quench in SFCLs connected in series are on the way through methods such as the artificial control of quench speed.peed.