• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.2 no.4
• /
• pp.511-517
• /
• 1998

In this paper a new technique to generate spreading code sequences in the CDMA communication is introduced. It is an effective method to generate optimal code sequences using the orthogonality of wavelet packet basis set of subspaces. With a three-stage Quadrature Mirror Filter(QMF), generation of optimal code sequences has been demonstrated. Since these generated optimal code sequences are non-binary and have an arbitrary waveform which is different from that of the conventional PN-based Gold code sequences, a strong security against the intended interceptor is feasible. Encouraging good correlation properties are also achieved with this new method.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.950-951
• /
• 2006

This paper proposed a new driving method for the stable lighting of CDM lamps. To avoid the acoustic resonance in the proposed method, the inverter output voltage will be a low frequency rectangular waveform containing a sinusoidal voltage ripple with high frequency. Moreover, the realtime power control of the inverter can be achieved by the control of switching currents. To verify the validity of tile proposed method, a prototype set-up was build and the experimental results are presented in this paper.

• Journal of Power Electronics
• /
• v.1 no.1
• /
• pp.26-35
• /
• 2001

In most inverter/converter applications SVPWM method is a preferred approach since it shows good characteristics in linear modulation range and waveform quality. In this paper, we propose a new carrier based SVPWM method for multi-level system, First, we survey the conventional carrier based SVPWM method, and investigate the problem of the conventional one for the multi-level system with the focus on the switching frequency harmonic flux trajectories. Finally, we propose a new carrier based SVPWM method that can reduce harmonic distortion. Simulation and experimental results are given for verification of the proposed SVPWM method.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.5 no.3
• /
• pp.54-63
• /
• 1991

This paper describes an effort to develope a microcomputer-based parameter measurement system for a brushless DC motor. Back EMF equation is derived from back EMF waveform of a brushless DC motor. To minimize error the due to the ripple component in the measured armature current, digital averaging filter is employed. The whole identification process of signal generation, measurement parameter determination is fully automated. A new identification algorithm for the brushless DC motor parameters is developed. New parameter correction method is proposed using the deadzone current and the time to reach the peak current. In the proposed correction method, the measured current is in excellent agreement with the estimated current.

• Proceedings of the KIEE Conference
• /
• 2003.10a
• /
• pp.258-260
• /
• 2003

In this paper, we study the reduction of the Dynamic False Contour in a new driving method. This method divides scan lines into Multi Blocks, and drives both selective write and selective erase address. Because of the characteristic of proposed waveform, each scan line has a different sustain pulse weight. Therefore, the Dynamic False Contour occurs seriously in the boundary of each Block. Finally, if scan-lines tie several lines, the Dynamic False Contour can reduce in the boundary of each Block.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.5
• /
• pp.450-456
• /
• 2005

In this paper new 60-step inverter system for medium-to-large scale STATCOM is proposed and operating principle along with control method is detailed. A simple auxiliary circuit is employed to Improve output voltage waveform of 12-step into 60-step. The proposed scheme could be a cost effective approach in high power application such as 10Mvar to 30Mvar STATCOM. Experimental results from a 2KVA laboratory prototype show validity of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.2
• /
• pp.80-86
• /
• 2003

In this paper, a new three-phase voltage-source inverter topology for high voltage and high Power applications is proposed to improve the quality of output voltage waveform. A chain converter which is used as an auxiliary circuit generates a ripple voltage and injects it to the conventional 12-step inverter. Thus, the injection of the ripple voltage results in 36-step operation with a link and 60-step operation with two links. The proposed inverter is compared to the conventional multilevel inverter in the viewpoint of ratings of phase- shifting transformers, switching devices and capacitors employed. The proposed scheme is simple to control capacitor voltages compared to the conventional schems and is cost effective for high voltage and high power application over several tens of MVA. The proposed approach is validated through simulation, and the experimental results are provided from a 2KVA laboratory prototype.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.10
• /
• pp.501-507
• /
• 2001

In this paper, new high-efficiency zero voltage switching (ZVS) AC-DC boost converter is proposed to achieve power factor correction by simplifing energy recovery circuit. A lot of high power factor correction circuits have been proposed and applied to increase input power factor and efficiency. Most of these circuits may obtain unity power factor and achieve sinusoidal current waveform with zero voltage or/and zero current switching. However, it is difficult for them to obtain low cost, small size, low weight, and low noise. The topology proposed to improve these problems can compact the devices in circuit and can achieve high efficiency ZVS AC-DC boost converter. Simulation and experimental results show that this topology is capable of obtaining high power factor and increasing the efficiency of the system.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.16 no.6
• /
• pp.31-39
• /
• 1979

This paper dealt with a general the Qrem of frequency doubler. By summarizing the frequency doubler theorems, a new frequency doubter theorem can be derived. "In time invarient system, if the input waveform shows the half-wave symmetric characteristic and if the even function is the mapping from input into output, then the frequency of output is at least 2-times of input frequency." By the theorem, this paper propose a new wide band square wave frequency doublerusing negative resistance circuit.e circuit.

• Progress in Medical Physics
• /
• v.6 no.1
• /
• pp.3-11
• /
• 1995

A technique based on bispectrum averaging is described for generally recovering the signal waveform from a set of noisy signals with variable signal delay. The technique does not require explicit time alignment of signals and initial estimate of sigals and initial etimate of signal. The new method is suggested and is compared with other methods. This method are numerically investigated using computer generated-data and a phtsiological signal and noise. Some expermeental results for the evoked potential studies that demonstrate the technique are given. The results show the effectiveness of the technique : various potential applictions of the techique might be expected.