• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.281-284
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• 2001

This paper presents implementation of digitally speed sensorless control system for induction motor with a direct torque control(DTC) using 32bit DSP TMS320C31. The system are closed loop stator flux and torque observer for wide speed range that inputs are currents and voltages sensing of motor terminal, MRAS with rotor flux linkages for the speed turning signal, two hysteresis controllers, optimal switching look-up table and IGBT voltage source inverter. There are suggested a control algorithm and system, and given simulation and implementation results on the 2.2Kw general purposed induction motor.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.56-63
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• 2005

The radome boresight error degrades the microwave seeker ability and the missile guidance performance. It increases the miss distance, also. This paper propose a method of radome boresight error measurement and compensation. The compensation method consist of radome analysis and radome compensation. In the radome analysis stage, we can know that the electromagnetic characteristics distorted by radome. In the compensation stage, the look-up table is built and used for compensation. The test uses a FMS(Flight motion simulator) and adjusts the FMS setup error for more accuracy. The result shows that not using an elaborate radome measurement equipment, the radome boresight error is well compensated easily.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.62-70
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• 2007

In this paper, the boost Power Factor Correction(PFC) technique for Direct Torque Control(DTC) of brushless DC motor drive in the constant torque region is implemented on a TMS320F2812DSP. Unlike conventional six-step PWM current control, by properly selecting the inverter voltage space vectors of the two-phase conduction mode from a simple look-up table at a predefined sampling time, the desired quasi-square wave current is obtained, therefore a much faster torque response is achieved compared to conventional current control. Furthermore, to eliminate the low-frequency torque oscillations caused by the non-ideal trapezoidal shape of the actual back-EMF waveform of the BLDC motor, a pre-stored back-EMF versus position look-up table is designed. The duty cycle of the boost converter is determined by a control algorithm based on the input voltage, output voltage which is the dc-link of the BLDC motor drive, and inductor current using average current control method with input voltage feed-forward compensation during each sampling period of the drive system. With the emergence of high-speed digital signal processors(DSPs), both PFC and simple DTC algorithms can be executed during a single sampling period of the BLDC motor drive. In the proposed method, since no PWM algorithm is required for DTC or BLDC motor drive, only one PWM output for the boost converter with 80 kHz switching frequency is used in a TMS320F2812 DSP. The validity and effectiveness of the proposed DTC of BLDC motor drive scheme with PFC are verified through the experimental results. The test results verify that the proposed PFC for DTC of BLDC motor drive improves power factor considerably from 0.77 to as close as 0.9997 with and without load conditions.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.986-988
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• 2001

This paper presents a digitally speed sensorless control system for induction motor with direct torque control (DTC). Some drawbacks of the classical DTC are the relatively large torque ripple in a low speed range and notable current pulsation during steady state. They are reflected speed response and increased acoustical noise. In this paper, the DTC quick response are preserved at transient state, while better qualify steady state performance is produced by space vector modulation (SVM). The system are closed loop stator flux and torque observer for wide speed range that inputs are currents and voltages sensing of motor terminal, model reference adaptive control (MRAC) with rotor flux linkages for the speed fuming signal at low speed range, two hysteresis controllers and optimal switching look-up table. Simulation results of the suggest system for the 2.2 [kW] general purposed induction motor are presented and discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.399-405
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• 2002

This paper presents an implementation of digital high-performance Position sensorless motion control system of an induction motor drives with Direct Torque Control(DTC). The system consist of closed loop stator flux and torque observer, speed and torque estimators, two hysteresis controller, optimal switching look-up table, IGBT voltage source inverter, and TMS320C31 DSP board. The stator flux observer is based on the combined current and voltage model with stator flux feedback adaptive control of which inputs are current and voltage sensed on motor terminal for wide speed range. The speed observer is using the model reference adaptive system(MRAS) with rotor flux linkages for speed turning signal. The simulation and experimental results are provided to evacuate the consistency and the performance of the suggested position sensorless control algorithm. The developed position sensorless system are shown a good motion control response characteristic and high performance features using 2.2[kw] general purposed induction motor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.2
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• pp.47-54
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• 1982

In this paper, a improved per-channel PCM Coder with 1-bit interpolation is proposed. The coder converts a telephone signal to 15-segments u-law PCM signal of a large dynamic range. The A/D conversion technique of the proposed converter requires a feedback loop around a quantizer operates at high speed, and a accumulater for accumulating the quantized values to provide PCM outputs. To obtain both linear and compressed PCM signals a improved table look-up method is presented. The operations of the proposed converter are certified through the experiments to be good. The experimental circuit comprises TTL logic gates, a resistive D/Z converter and a simple differential amplifier. From the results of the experiments, it is known that the proposed converter has many advantage to be adopted economically for per-channel onverter used in rural area service.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.1
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• pp.18-27
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• 2002

This paper presents an implementation of digital high-performance speed sensorless control system of an induction motor drives with Direct Torque Control(DTC). The system consists of closed loop stator flux and torque observer, speed and torque estimators, two hysteresis controllers, an optimal switching look-up table, IGBT voltage source inverter, and TMS320C31 DSP controller board. The stator flux observer is based on the combined current and voltage model with stator flux feedback adaptive control for wide speed range. The speed estimator is using the model reference adaptive system(MRAS) with rotor flux linkages for speed turning signal estimation. In order to prove the suggested speed sensorless control algorithm, and to obtain a high-dynamic robust adaptive performance, we have some simulations and actual experiments at low(20rpm) and high(1000rpm) speed areas. The developed speed sensorless system are shown a good speed control response characteristic, and high performance features using 2.2[kW] general purposed induction motor.

• Clinical and Experimental Reproductive Medicine
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• v.10 no.2
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• pp.13-23
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• 1983

In recent days, family planning is not only a problem limitted to our country but an important problem for the while world to solve. Up to present, various methods of sterilization have been developed for population control. When a patient with a previous tubal sterilization by operative method develops any symptoms and signs of pregnancy, we strongly consider it ectopic pregnancy and intrauterine pregnancy. As the cause of sterilization failure, we think that the tubal loop sloughs away and tubal ends either unite and recanalization results or heal and failure of union results in fistula. This present study considered of the 34 cases of ectopic pregnancies and 2 cases of intrauterine pregnancies after tubal sterilization by laparoscopy and Pomeroy's method, at the Dept. of Gynecol. in Kyung Hee University Hospital, during 6 years from Jan. 1977 to Dec. 1982. Authors take result in this study retrospectively. 1. Mean age was 33.7 years for the laparoscopic tubal sterilization group, 31.5 years for the Pomeroy tubal sterilization group. 2. The number of mean gravida and parity at the sterilization was 4.9, 2.8 for the laparoscopic tubal sterilization group, 4.2, 2.2 for the Pomeroy tubal sterilization group, :respectively. 3. The number of mean artificial abortion at the sterilization was all 2.2 for the laparoscopic and Pomeroy tubal sterilization groups. 4. Mean intervals from the tubal surgery to the incidental pregnancy was 3.2 years for the laparoscopic tubal sterilization group, and 3.8 years for the Pomeroy tubal sterilization group. 5. 63.3% of the laparoscopic tubal sterilization group had problem of inadequate tubal ligation, in comparison to having no inadequate problem in the Pomeroy tubal sterilization group. 6. The previous tubal sterilized scar was found to be 6 cases (17.6%) of inner portion, 15 cases (44.4%) of midportion, 13 cases (38.2%) of outer portion at the time of operation. The tubal site of ectopic pregnancy was found to be 23 cases (67.6%) of ampullary portion,S cases ( 4.7%) of isthmic and fimbrial portion, respectively. 7. The causes of table sterilization failure were, in order of frequency, technical error (19 cases), fistula formation (6 cases) and recanalization (5 cases) for the laparoscopic tubal sterilization group and fistula formation (2 cases), technical error (l case), recanalization (l case) fo the Pomeroy tubal sterilization group. 8. As the new applicated contraceptive method in incidental pregnant patient, Authors used 2 gravigard insertion for the two intrauterine pregnancy and 34 Pomeroys' tubal ligation, 2 total abdominal hysterectomy (due to associated pelvic inflammatory disease) for the 36 tubal pregnancy.