• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4119-4124
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• 2011

In a MPC coding using excitation source of voiced and unvoiced, it would be a distortion of speech waveform in case of increasing or decreasing of speech signal amplitude in a frame. This is caused by normalization of synthesis speech signal in the process of restoration the multi-pulses of representation section. To solve this problem, this paper present a method of amplitude compensation(AC-MPC) in a multi-pulses each pitch interval in order to reduce distortion of speech waveform. I was confirmed that the method can be synthesized close to the original speech waveform. And I evaluate the MPC and AC-MPC using amplitude compensation method. As a result, SNRseg of AC-MPC was improved 0.7dB for female voice and 0.7dB for male voice respectively. Compared to the MPC, SNRseg of AC-MPC has been improved that I was able to control the distortion of the speech waveform finally. And so, I expect to be able to this method for cellular phone and smart phone using excitation source of low bit rate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.584-588
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• 2021

The impedance of the speaker is likely to be recognized as a fixed value. However, speaker impedance continues to vary with frequency variation, especially larger in resonant frequency region. The sound pressure level of loudspeakers is determined by the current flowing throughout the coil that consists loudspeakers. If loudspeakers are driven by voltage, sound pressure level of the loudspeaker is distorted by the variation of loudspeaker impedance. Current-drive of loudspeakers can solve this problem, but distortion of sound pressure level occurs in low frequencies due to resonance. The distortion can degrade the sound quality of the sound system. So to solve this problem, In this paper, we propose a resonance compensation circuit using DSP. we simulates audio systems using an equivalent model of loudspeakers to verify distortion of sound pressure level due to impedance variation and propose a circuit to compensate it. The proposed circuit is configured using a state variable filter and it can adjust the center frequency and output, so it will be used various sound systems.

• The Journal of the Acoustical Society of Korea
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• v.17 no.3E
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• pp.53-57
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• 1998

Spectral information at a speech coder should be quantized with sufficient accuracy to keep perceptually transparent output speech. Spectral information at a low bit rate speech coder is usually transformed into corresponding line spectrum pair parameters and is often quantized with a vector quantization algorithm. As the vector quantization algorithm generally has high complexity in the optimal code vector searching routine, the complexity reduction in that routine is investigated using the ordering property of the line spectrum pair. When the proposed complexity reduction algorithm is applied to the well-known split vector quantization algorithm, the 46% complexity reduction is achieved in the distortion measure compu-tation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1584-1588
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• 2007

This paper proposed the voltage compulsion method that used chopper for light dimming control of fluorescent lamp. During the dimming period, electronic ballasts have the bad characteristics such as low power factor, high THD(Total Harmonic Distortion) and etc. The proposed dimmer improves power factor, THD of electronic ballast and has benefit such as low cost, simple build up.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.423-431
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• 1997

A new single-stage/single-switched forward converter with magnetic coupled nondissipa-tive snubber is proposed. The proposed converter gives the good power factor correction (PFC), low current harmonic distortion, and tight output voltage regulation. The prototype shows the IEC 555-2 requirements are met satisfactorily with nearly unity power factor. This proposed converter with magnetic coupled nondissipative snubber is particularly suited for low power level power supply applications.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.410-412
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• 1997

A new method to improve the THD of the three phase rectifiers is introduced in this paper. The main features of this paper are low cost, high efficiency and simplicity. The proposed 3 bidirectional switches and their operation are presented. A simulation and experiment results show its good action.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.384-387
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• 2000

In this paper Power factor correction circuit of single-phase three-level boost converter is proposed. The advantage of the proposed control scheme for three-level boost converter are low blocking voltage of each power device low THD(Total Harmonic Distortion) and high power factor. The control scheme is based on the current comparator capacitor compensator and region detector, In simulations the proposed system is validated.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.635-639
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• 1998

When the low pressure injection molded parts are debinded by wicking and subsequent thermal pyrolysis the optimum transition point from wicking to thermal pyrolysis is just after the completion of the constant wicking rate period. Even when the partially debinded parts were heated at 5$^{\circ}C$/min after reaching the 1st falling rate period the debinding defects such as distortion and cracks were not found.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.329-330
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• 2015

This paper introduces a low-frequency switching method for the neutral line of TNPC inverters to achieve high efficiency. By applying the method, the switching loss in the neutral line is reduced. In order to compensate the current distortion near zero-crossing points, the partial switching strategy is applied. Both the simulation and the experimental results verify the usefulness of the proposed method.

• The Journal of Pediatrics of Korean Medicine
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• v.16 no.2
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• pp.171-185
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• 2002

Objectives : The purpose of this study was to investigate the spine distortion and self-conscious pain in high school students. Method : Using the phase-shifting moire developed by KAIST(Korea Advanced Institute of Science and Technology) we measured the back surface distortion, and using questionnaire investigation, we investigated the self-conscious pain in 30 high school students(17 boy students and 13 girl students). Results : This study show that low back pain was most cases, and next headache, upper back pain, abdominal pain, neck pain, shoulder pain, leg pain, chest pain and gluteal pain. The ratio of each self-conscious pain was 90.0%, 86.7%, 83.3%, 83.3%, 80.0%, 76.7%, 66.7%, 33.3%, 33.3%, 30.0%. In remainder value of left and right shoulder, above of 3.0 were three students., above 2.0 to bellow 3.0 were 10 students, bellow 2.0 were 17 students. In remainder value of left and right gluteal, above of 2.0 was one students, above 1.0 to bellow 2.0 were 18 students, bellow 1.0 were 10 students. In remainder value of cervical vertical line to left and right axillae, above 4.0 was 1 student, above 3.0 to bellow 2.0 were 2 students, above 2.0 to bellow 3.0 were 3 students, above 1.0 to bellow 2.0 were 16 students, bellow 1.0 were 7 students. In remainder value of gluteal vertical line to left and right axillae, above 6.0 was 1 student, above 5.0 to bellow 6.0 were 7 students, above 4.0 to bellow 5.0 were 3 students, above 3.0 to bellow 4.0 were 2 students, above 2.0 to bellow 3.0 were 5 students, above 1.0 to bellow 2.0 were 7 students, bellow 1.0 were 5 students. In remainder value of cervical vertical line to gluteal vertical line, above 40 was 1 student, above 3.0 to bellow 4.0 were 4 students, above 3.0 to bellow 3.0 were 6 students, above 1.0 to bellow 2.0 were 8 students, bellow 1.0 were 11 students. Conclusion : It is suggested that the significant correlation exist between the spinal distortion and self-conscious pain. And we can find many cases as spinal distortion in high school students also. We have to study further more about juvenile postural distortion and it's prevention.