• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.144-144
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• 2013

Non-thermal atmospheric pressure plasmas have recently garnered much attention due to their unique physical and chemical properties that are sometimes significantly different from those of low pressure plasmas. It can offer many possible application areas including nano and bio/medical areas. Many different types of plasma sources have been developed for specific needs, which can be one of the important merits of the atmospheric pressure plasmas since characteristics of the produced plasma depend significantly on operating parameters such as driving frequency, supply gas type, driving voltage waveform, gas flow rate, gas composition, geometrical factor etc. Among many source configurations, parallel plate type geometry is one of the simplest configurations so that it can offer many insights for understanding basic underlying physics. Traditionally, the parallel plate type set up has been studied actively for understanding low pressure plasma physics along with extensive employment in industries for the same reason. By considering that understanding basic physics, in conjunction with plasma-surface interactions especially for nano & bio materials, should be pursued in parallel with applications, we investigated atmospheric pressure discharge characteristics in a parallel plate type capacitive discharge source with two parallel copper electrodes of 60 mm in diameter and several millimeters in gap distance. In this presentation, some plasma characteristics by varying many operating variables such as inter-electrode distance, gas pressure, gas composition, driving frequency etc will be discussed. The results may be utilized for plasma control for widening application flexibility.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.7
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• pp.957-963
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• 2007

In this paper, Nonlinear Autoregressive (NAR) method based on Least Square-Support Vector Regression (LS-SVR) is introduced and tested for nonlinear sustained vowel modeling. In the database of total 43 sustained vowel of Benign Vocal Fold Lesions having aperiodic waveform, this nonlinear synthesizer near perfectly reproduced chaotic sustained vowels, and also conserved the naturalness of sound such as jitter, compared to Linear Predictive Coding does not keep these naturalness. However, the results of some phonation are quite different from the original sounds. These results are assumed that single-band model can not afford to control and decompose the high frequency components. Therefore multi-band model with wavelet filterbank is adopted for substituting single band model. As a results, multi-band model results in improved stability. Finally, nonlinear sustained vowel modeling using NAR based on LS-SVR can successfully reconstruct synthesized sounds nearly similar to original voiced sounds.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.576-585
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• 2001

In this paper, we investigated the method of compensation for optical pulse shape distortion due to both chromatic dispersion and SPM(self phase modulation) in a single mode fiber We selected MSSI(mid-span spectral inversion) as compensation method using OPC(optical phase conjugator). We used EOP(eye-opening penalty) parameter in order to evaluate the efficiency of waveform distortion compensation. In this paper, we induced optimum pump power level in optical phase conjugator through analytic method of computer simulation. And we investigated input signal power range being able to maintain stable reception performance under the condition of optimum pump power. We verified the possibility of high performance optical transmission system realization through the inducement and application of optimum pump power, input signal power and in-line amplifier spacing, because power control is important in the compensation for optical pulse distortion.

• Journal of IKEEE
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• v.24 no.1
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• pp.19-24
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• 2020

This paper presents a 3-level, 2-level SVPWM technique with 100 kHz switching using Verilog HDL, one of the languages of FPGA. In the case of IGBT devices mainly used in inverters, they have a switching frequency around 20kHz. Recent research and development of next-generation power semiconductor devices such as GAN has enabled switching of more than 100kHz, which can miniaturize power converters, and apply various new algorithms due to the injection of harmonics. In the existing system using the IGBT, the control using the DSP is common, but the controller configuration for 100 kHz switching requires the use of FPGA. Therefore, this paper explains the theory and implementation of SVPWM applied to two-level and three-level inverters using FPGAs and verifies the performance through the output waveform. In addition, this paper implements 3-level SVPWM by using only one carrier instead of using two carriers in the conventional method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.40-47
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• 2007

High speed electric trains have nonlinear loads including converters and inverters for the control synchronous motors. Harmonic field measurements have shown that the harmonic contents of a waveform varies with time. Direct application of the harmonic assessment to the snapshot measurements would result in ambiguous conclusions depending on which instant is sampled. A cumulative probablistic approach is the most commonly used method to solve time varying harmonics. Harmonic simulations are performed to evaluate the harmonic voltage and current distortions throughout the system. This paper provides an in depth analysis on harmonics field measurement of the high speed electric train loads, harmonics assessment by the international harmonic standards IEC 61000-3-6 and IEEE Std. 519-l992, and harmonics simulation using EDSA program for the case study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.94-105
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• 2010

To detect faults in an inverter-fed permanent magnet synchronous motor (PMSM) drive under the circumstance having faults in a stator winding and inverter switch, an on-line basis fault detecting scheme during operation is presented. The proposed scheme is achieved by monitoring the second-order harmonic component in q-axis current and the fault is detected by comparing these components with those in normal conditions. The linear interpolation method is employed to determine the harmonic data in normal operating conditions. As soon as the fault is detected, the operating mode is changed to identify a fault type using the phase current waveform. To verify the effectiveness of the proposed fault detecting scheme, a test motor to allow inter-turn short in the stator winding has been built. The entire control algorithm is implemented using DSP TMS320F28335. Without requiring an additional hardware, the fault can be effectively detected by the proposed scheme during operation so long as the steady-state condition is satisfied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.834-837
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• 2015

In this paper, we designed the FPGA hardware-based real-time ECG simulator, which generates an analog ECG signal within the range of 0 to 5 volts and described function. The ECG signal generated by the simulator can be applied to laboratory tests, the medical device, and the calibration study in various ways. ECG signals generated by simulator are obtained with conventional 24bit quantization to generate the signal data, and they are sampled and quantized to 1kHz of the 8-bit resolution when used as actual data. The proposed simulator is implemented using xilix Spartan-3 and data are transmitted through an RS-232 between the PC and the FPGA simulator. The transmitted data are stored in the memory and the stored data are printed out with the analog ECG signal through DAC (0808). It can also control the heart rate (HR) via the two buttons level UP-DOWN. We used existing ECG input rating for the evaluation of the designed system and evaluated differential circuit for obtaining QRS waveform and the output signal. We finally could obtained proper the result.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.228-234
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• 2009

In this paper, we present an analytical method that provides fast and efficient evaluation of the power losses and the conversion efficiency for phase-shift controlled full-bridge converter. In the proposed method, the conduction losses are evaluated by calculating the effective values of the ideal current waveform first and incorporating them into an exact equivalent circuit model of the phase-shift controlled full-bridge converter that includes all the parasitic resistances of the circuit components. While the conduction losses are accurately accounted for the synchronous rectification, the core losses are assumed to be negligible in order to simplify the analysis. The validity and accuracy of the proposed method are verified with experiments on a prototype phase-shift controlled full-bridge converter. An excellent correlation between the experiments and theories are obtained for the input voltages of 400V, output voltage 12V and maximum power 720W.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.233-236
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• 1996

We are exposed to the various external stimuli input from the environment, which cause emotional changes based on the characteristics of the stimuli. Unfortunately, there are no quantitative results on relationship between human sensibility and the characteristics of physiological signals. The objective of this study was to quantify EEG signals evoked by auditory stimulation based on the assumption that the analysis of the variability on the characteristics of the EEG waveform may provide the significant information regarding changes in psychological states of the subject. The experiment was devised with seven experimental conditions, which are control and six different types of auditory stimulation. Twenty subjects were used to obtain EEGs while introducing auditory stimulation. Wavelet transformation was employed to analyze the EEG signals. The results showed that the reconstructed signals at the decomposition level revealed the different energy value on the EEG signals. Also, general patterns of EEG signals in rest state compare with negative and positive stimulus were found. This study could be extended to estabilish an algorithm which distinguishes psychophysiological states of the subjects exposed to the auditory stimulation.

• Korean Journal of Acupuncture
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• v.27 no.1
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• pp.1-12
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• 2010

Objectives: The purpose of this study is to gain the objective indicators for the classification of hypertension by oriental medical pulse diagnosis, through finding out the parameters which can distinguish the pulse of hypertensive patient from that of normal subject, and characterizes the wiry pulse of hypertension. Methods: 30-59 yr, male, 946 healthy volunteers and 35 hypertensive patients were enrolled in this study. All the hypertensive patients were taking medicine to control the blood pressure and the blood pressure of the hypertension group was not statistically different from that of the normal healthy group. Data were acquired using 3 dimensional pulse imaging analyser(DMP-3000, DAEYOMEDI, KOREA) and analysed according to the age bands and the applied pressure levels. Results: 1. RAI/t, w/t and t2/t decreased with the levels of applied pressure and increased with age in the normal healthy group, not in the hypertension group. 2. RAI/t, w/t, t2/t were significantly higher in the hypertension group than the normal healthy group in the 30-age band, and elasticity coefficient was higher in the hypertension group than the normal healthy group in the 40-age band. 3. Researches on the patients without hypotensive agents are needed to figure out whether these parameters are the components of hypertensive wiry pulse. Conclusions: Analysing the radial pulse at 5 applied pressure levels using 3 dimensional pulse imaging analyser may be useful to differentiate the pulses of the hypertensive patients from those of the normal subjects, and characterize the hypertension.