• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.5
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• pp.345-351
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• 2000

To improve the current waveform of diode rectifiers, we propose a new operating principle of the voltage diode rectifiers. In the conventional voltage rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses ones and a small reactor not boost the output voltage but improve the input current waveform. A circuit design method is shown and confirmed simulation. It explained that compared conventional PWM(Pulse-width modulated)inverter with HPWM(Half Pulse-width modulated)inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting. Output voltage and current of this paper were applied for real air-conditioner.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.492-496
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• 2004

When using a conventional power factor correction circuit, a comparatively huge capacitor is used to boost-up output voltage. It has a large amount of harmonic distortion in the input current waveform. To improve the input current waveform of diode rectifiers, we propose a new operating principle for the power factor correction circuit. Due to the fact that the proposed circuit uses smaller ones and a smaller reactor, the output voltage increases and obtains higher input current waveforms. These are suitable for the harmonics guidelines. The proposed circuit is able to obtain higher power factor and efficiency. Also, it has reduced switching loss and held over-shooting by using an inverter of eliminated dead-time HPWM that has non-linear impedance circuits to make up diodes, capacitance and a reactor. We compared the conventional PWM inverter and proposed HPWM inverters and found that a high input power factor of 97[%] and an efficiency of 98[%] were also obtained.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.1
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• pp.16-21
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• 1999

The analysis of distribution line faults is essential to the proper protections of the power system. A high impedance fault test, which was carried in Korean electric power systems, it was found that a arcing phenomenon occurred during the high level portion of conductor voltage in each cycle. In this paper, we propose a new method for detection of high impedance faults, which uses the arcing fault current difference during high voltage and low voltage portion of conductor voltage waveform. To extract this difference, we diveded one cycle fault current into equal spanned four data windows according to the magnitude of voltage waveform and applied fast fourier transform(FFT) to each data window. The frequency spectrum of current wavefrom in each portion are used as the inputs of neural network and is trained to detect high impedance faults. The proposed method shows improved accuracy when applied to staged fault data and fault-like load.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.479-481
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• 2007

This paper presented a actual conditions on a false-tripping of ELB(Earth Leakage Breakers) and an assessment of the harmonics due to non-linear electronic equipment such as personal computers, rectifier, electric furnace and test equipments in plant installations. Actual conditions on a failure of ELB were surveyed and analyzed by making up a question to safety managers of plant installations. Also, power quality measurements such as harmonic currents, voltage and current waveform and current imbalance were made at various plant installations where nuisance tripping of ELB is often occurred. The results of this study can be used in making decisions regarding cause of ELB trip and operating and tripping characteristics test of ELB when subjected to distorted current waveform.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.190-195
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• 2013

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1167-1174
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• 2008

The measurement of two-dimensional magnetic properties of electrical steel sheet using single sheet tester (SST) requires to control the B-waveform as sinusoidal. The SST electric circuit, in general, has inductance, and this makes the phase lag in electric current. For this reason, the induced voltages of H- or B-coil may have phase difference from the exciting voltage. In this paper, a new algorithm is developed to compensate the phase difference and makes the B-waveform control efficient. The developed algorithm experimentally calculates the phase difference based on the measured waveform of the induced voltage for the magnetic field intensity along transverse direction. By using the proposed algorithm, the two-dimensional magnetic properties of grain-orientated electrical steel sheet (30PG110) is measured up to 2T. By comparing the measured B- and H-waveforms, the effectiveness of the proposed algorithm is proven.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.87-93
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• 2005

In this paper, we analyzed ignition characteristics of combustible material and the waveform of power dissipation, voltage and current by poor contact. And the surface structure of plug by poor contact was analyzed. In the results of experiment, the heat generated by poor contact and ignited the combustible material on power cord sets. The insulation material was molten and carbonized by the heat conduction though plug pit and voids were formed inside of insulation material. The waveform of voltage and power dissipation distorted because of a growth of oxidation by poor contact. In particular, in case that load was big load, the waveform of voltage and power dissipation severely distorted as with the passage of time. The surface of plug pin was changed from erosion mark to welding mark according to big load. The results will be applied to the cause analysis of electrical disaster.

• Journal of the Korean Magnetics Society
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• v.22 no.1
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• pp.23-26
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• 2012

New digital feedback algorithm was developed to measure iron loss of soft magnetic materials under a condition of sinusoidal flux waveform. $V_{in}$(B) curve was used instead of H(B) curve to decide next input waveform in the feedback module so that adjusting phases of current waveform, flux waveform, and input waveform could be removed. The effectiveness of the developed algorithm was verified when iron loss of ferrite cores was measured under frequencies of 1 and 10 kHz.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1339-1346
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• 2024

Electrorefining in molten salts is used for purifying actinides. Optimizing electrorefining is key to minimizing processing time and radiological waste. One possible way of improving electrorefining efficiency is using an AC superimposed DC waveform. This waveform has demonstrated potential benefits in aqueous solutions but has never been utilized in a molten metal, molten salt application. This work investigates the effects of using an AC superimposed DC waveform on molten bismuth electrorefining in a molten LiCl-KCl-CaCl2 eutectic. Bismuth has been identified as a potential surrogate for plutonium electrorefining and a potential cathode in electrorefining used nuclear fuel (UNF). All electrorefining runs resulted in a high purity cathode ring and high yield with exception of the run using a low-frequency, high-amplitude superimposed AC waveform, which experienced some contamination and a lower yield. The other three AC superimposed DC runs experienced an average yield 6.7 % higher than the average yield of the DC runs. The electrorefining run using the high-frequency, high-amplitude superimposed AC signal had the highest yield. It is recommended in future studies to investigate the statistical variability of electrorefining yield and current efficiency and the impact of AC superimposed DC waveforms on solidified bismuth anodes.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.219-225
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• 2014

This paper describes an IC for Power Factor Correction. It can use electrical appliances which convert power from AC to DC. The power factor can be influenced not only phase difference of voltage and current but also sudden change of current waveform. This circuit enables current wave supplied to load by close to sinusoidal and minimum phase difference of voltage and current waveform. A self oscillated 10[kHz]~100[kHz] pulse signal converted to PWM waveform and it chops rectified full wave AC power which flows to load device. The multiplier and zero current detector circuit, UVLO, OVP, BGR circuits were designed. This IC has been designed and whole chip simulation use 0.5[um] double poly, double metal 20[V] CMOS process.