• Journal of IKEEE
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• v.23 no.1
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• pp.164-172
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• 2019

Current clinical methods for diagnosing urination disorder are invasive, expensive, and very inconvenient to perform continuous monitoring. EIT is a non-invasive technique that injects electrical current through an external electrodes and measures the induced voltage to visualize the internal electrical (impedance) characteristics, which makes it possible to monitor bladder conditions with low cost. The signal characteristics of the measured voltage data changes according to the current pattern injected through the electrode and affects reconstruction performance. In this paper, image reconstruction performance is compared and analyzed according to the injected current patterns to maximize the sensitivity to the variation of bladder size.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1267-1269
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• 2000

New switching signal pattern for four switches is proposed to prevent the shortage of PWM ac choppers. In the proposed technique, four signals to four power switches are generated without current transformer, while the conventional technique requires sensing the polarity of input voltage by voltage comparator and checking the direction of input current by the current transformer. The signal circuit built by the proposed technique is simple, and reduces also the switching loss.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1934-1936
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• 1998

This paper proposes a new control scheme for enhanced power factor in the boost type AC/DC rectifier. The control scheme is to generate duty-cycle pattern without instantaneous measurement of the input line current. With a very simple controller structure the line current is forced to trace a sinusoid in phase with input voltage. The simulation results show the validity of the proposed control scheme.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.475-478
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• 2006

In electrical impedance tomography (EIT) an array of electrodes is attached on the boundary of an object and small alternating currents are injected through these electrodes, and then the resulting voltages are measured. An estimation for the cross-sectional resistivity distribution in the object is obtained by using these current and voltage data in a nondestructive manner. In this paper, the electrical impedance imaging of two-phase flows undergoing rapid transient is considered with a special emphasis on the effect of the current pattern on the image reconstruction. The trigonometric current pattern, which is commonly used in the conventional static electrical impedance imaging, shows poor performance in case of the dynamic imaging considered in this work. Extensive numerical experiments are conducted with various kinds of current patterns and their effects on the image reconstruction performance are examined.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.6
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• pp.445-451
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• 2019

An input power estimation method of a three-phase inverter for the high-efficiency operation of AC motors is proposed. Measuring devices, such as DC link voltage and input current sensors, are required to obtain the input power of the inverter. In the proposed method, the input power of the inverter can be estimated without the input current sensor by using the phase current information of the AC motor and the switching pattern of the inverter. The proposed method is more robust to parameter error than conventional method. The validity of the input power estimation method is verified through experiments conducted on a 1 kW permanent-magnet synchronous motor drive system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.9
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• pp.510-516
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• 1999

In this paper, a new high-powerfactor control method for boost-type rectifier is proposed, which removes the necessity of input current sensing. This method generates a sinewave duty template only from the line voltage waveform and rectifier output, and reduces reactive power remarkably utilizing three compensation coefficients which are determined through experiments. These compensations make the input current to be in phase with the input voltage all over the load range. A prototype boost-type rectifier is designed and experimental results are presented.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.5
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• pp.1-8
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• 2011

This paper proposes a new input pattern generator for minimal leakage power in the nanometer CMOS technology considering all the leakage current components (sub-threshold leakage, gate tunneling leakage, band-to-band tunneling leakage). Using the accurate macro-model, a heuristic algorithm is developed to generate a input pattern for the minimum leakage. The algorithm applies to ISCAS85 benchmark circuits, and the results are compared with the results of Hspice. The simulation result shows that our method's accuracy is within a 5% difference of the Hspice simulation results. In addition, the simulation time of our method is far faster than that of the Hspice simulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.9
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• pp.445-452
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• 2001

Two switching signal patterns are proposed to prevent short circuit of PWM ac choppers. The voltage detection method and the current detection method are proposed to execute two switching signal patterns. In the voltage detection method, the dead-time has to be inserted to the switching signals after polarity of input voltage is checked by voltage transducer at input side. In the current detection method, the direction of load current is checked by current transducer at output side, and the dead-time delay is not considered. Controlling circuit built by current detection method is simple because the dead-time delay is considered. The experimental results are presented to prevent short circuit of ac chopper safely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5C
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• pp.486-492
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• 2003

The vigilance threshold of conventional fuzzy ART algorithm decide whether to permit the mismatch between any input pattern and stored pattern. If the vigilance threshold was large, despite of little difference among input and stored patterns, the input pattern may be classified to new category. On the other hand, if the vigilance threshold was small, the similarity between two patterns may be accepted in spite of lots of difference and the input pattern are classified to category of the stored pattern. Therefore, the vigilance threshold for the image recognition must be experientially set for the good result. Moreover, it may occur in the fuzzy ART algorithm that the information of stored patterns is lost in the weight-adjusting process and the rate of pattern recognition is dropped. In this paper, I proposed the enhanced fuzzy ART algorithm that supports the dynamical setting of the vigilance threshold using the generalized intersection operator of fuzzy logic and the weight value being adaptively set in proportional to the current weight change and the previous weight by reflecting the frequency of the selection of winner node. For the performance evaluation of the proposed method, we applied to the recognition of container identifiers from shipping container images. The experiment showed that the proposed method produced fewer clusters than conventional ART2 and fuzzy ART algorithm. and had tile higher recognition rate.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.535-540
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• 1998

This paper discusses a triple stage current source GTO inverter system for high power motor drives. The energy rebound circuit of the triple stage inverter not only controls the spike voltage of the GTO inverter but also facilitates PWM control of the thyristor rectifier operated at unity fundamental input power factor. Based on Pspice simulation and experiments, the principles and PWM pulse pattern for removing specific lower harmonics in the inverter's output current are discussed in detail.