• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.393-402
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• 2012

In this study, we propose a signal processing algorithm to measure the arousal level of a human subject using a PPG(Photoplethysmography) sensor. From the measured PPG signals, the arousal level is determined by PPI(Pulse to Pulse Interval) and discrete-time signal processing. We ran psychophysical experiments displaying visual stimuli on TV display while measuring PPG signal from a finger, where the nature landscape scenes were used for restorative effect, and the urban environments were used to stimulate the stress. However, the measured PPG signals may include noise due to subject movement and measurement error, which results in incorrect detections. In this paper, to mitigate the noise impact on stimulus detection, we propose a detecting algorithm using digital signal processing methods and statistics of measured signals. A filter is adopted to remove a high frequency noise and adaptively designed taking into account the statistics of the measured PPG signals. Moreover we employ a hysteresis method to reduce the distortion of PPI in decision of emotional. Via experiment, we show that the proposed scheme reduces signal noise and improves stimulus detection.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.172-173
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• 2011

전력시스템 주파수는 주파수 계전기용도 이외에 전력시스템에 대용량 집중전원 및 소규모 분산전원이 연계될 때 동기 검정 계전기와 발전기 및 소내 변압기의 과여자 상태를 감지하는 V/F 계전기에서도 사용된다. 주파수 계측장치는 주파수 및 주파수 편이를 실시간으로 정확하고 신속하게 측정함으로서 정규 주파수를 유지시키고 더 나아가 사고파급방지에 대한 책무를 수행해야 한다. DFT필터는 광범위하게 사용되었으나 주파수가 편이하게 되면 오차가 발생된다. 근래 웨이브릿 변환이 새로운 주목을 받고 것은 지속적인 연구 결과, 단일 반복 방정식 형태로 연산 부담이 적어 실시간 신호 처리에 적당한 고속 반복 이산 웨이브릿 변환이 제시되었기 때문으로 생각된다. 본 논문에서는 FRDWT에 의한 주파수 추정 기법을 제시하고자 한다. 제시된 기법의 성능 평가는 발전기 내부사고와 외부사고 데이터에 의해 이루어졌다.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.155-160
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• 2002

In this paper, a controller design for brushless linear motor is implemented. The designed controller is mainly composed of current, speed and position controller, which are carried out by the high-speed digital signal processor (DSP). In addition the PWM inverter is controlled by space voltage PWM method. This system is implemented by using 32-bit DSP (TMS320C31), a high-integrated logic device (EPM7192), and IPM (Intelligent Power Module) for compact and powerful system design. The experimental results show the effective performance of controller for the brushless linear motor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.167-169
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• 2001

In this paper, a controller design for high speed and stiffness linear motor is implemented. The designed controller is mainly composed of speed and current controller, which are carried out by the high-speed digital signal processor(DSP). In addition the PWM inverter is controlled by space voltage PWM method. This system is implemented by using 32-bit DSP(TMS320C31), a high-integrated logic device(EPM7128), and IPM(Intelligent Power Module) for compact and powerful system design. The experimental results show the effective performance of controller for high speed and stiffness linear motor.

• Journal of KSNVE
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• v.6 no.6
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• pp.851-856
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• 1996

The active noise cancellation system showing the effective convergence and stability has been studied by simplifying the controller structures using the weighting factors of control error path to the multi-channel filtered-x LMS algorithm which needs a lot of calculations and the performance has been verified experimentally. Besides, to implement the system performance in a vehicle cabin, experimental work for selecting the suitable numbers and positions of the microphones and speakers was accomplished. Effectively combining a TMS 320C 31 main processor conducting real number calculations and having various functions with other components, the purpose-built system board for active noise cancellation has been designed and with this board, car active noise cancellation system showing maximum stable 10dB noise reduction has been obtained at the car idling conditions above 3000rpm range.

• Journal of KSNVE
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• v.6 no.2
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• pp.205-214
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• 1996

Active noise control(ANC) requires the full capability of a modern digital signal processing module. This paper describes the digital signal processing unit which is designed for ANC of noise fields in passenger car. System hardware is designed to allow software controlled versatility as well as fully qutomatic operation. The developed system is provided with the ability to be self-operated except the case of upload/download of data and program between the personal computer and the system memory. Experimental results are presented to demonstrate ANC performance of noise fields in lightly damped enclosure and passenger car.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.116-124
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• 2009

This paper proposes a new Artificial-Intelligent(AI) Power Quality(PQ) diagnosis algorithm using Discrete Wavelet Transform(DWT), Fast Fourier Transform(FFT), Root-Mean-Square(RMS) value. The developed algorithm is able to detect and classify the PQ problems such as the transient, the voltage sag, the voltage swell, the voltage interruption and the total harmonics distortion. The 15.36[kHz] sampling frequency is used to measure the voltages in a power system. The measured signals are used for DWT, FFT, RMS calculation. For AI diagnosis of the PQ problems, a simple multi-layered Artificial Neural Network(ANN) with the back-propagation algorithm is adopted, programmed in C++ and tested in PSIM simulation studies. Finally, the algorithm, which is installed in MP PQ+256 with TI DSP320C6713, is proved to diagnose the PQ problems efficiently.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.2
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• pp.78-83
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• 2019

Sounds based machine fault diagnosis recovers all the studies that aim to detect automatically abnormal sound on machines using the acoustic emission by these machines. Conventional methods that use mathematical models have been found inaccurate because of the complexity of the industry machinery systems and the obvious existence of nonlinear factors such as noises. Therefore, any fault diagnosis issue can be treated as a pattern recognition problem. We propose here an automatic fault diagnosis method of hand drills using discrete wavelet transform(DWT) and pattern recognition techniques such as artificial neural networks(ANN). We first conduct a filtering analysis based on DWT. The power spectral density(PSD) is performed on the wavelet subband except for the highest and lowest low frequency subband. The PSD of the wavelet coefficients are extracted as our features for classifier based on ANN the pattern recognition part. The results show that the proposed method can be effectively used not only to detect defects but also to various automatic diagnosis system based on sound.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.6
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• pp.18-26
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• 2011

Debates concerning the competitive edge of leading 3DTV technology of the shutter glasses (SG) 3D and the film-type patterned retarder (FPR) are flaring up. Although SG technology enables Full-HD 3D vision, it requires complex systems including the sync transmitter (emitter), the sync processor chip, and the LCD lens in the active shutter glasses. In addition, the transferred sync-signal is easily affected by the external noise and a 3DTV viewer may feel flicker-effect caused by cross-talk of the left and right image. The operating current of the sync processor in the 3DTV active shutter glasses is gradually increasing to compensate the sync reconstruction error. The proposed chip is a low-power hardware sync processor based discrete-event SoC(system on a chip) designed specifically for the 3DTV active shutter glasses. This processor implements the newly designed power-saving techniques targeted for low-power operation in a noisy environment between 3DTV and the active shutter glasses. This design includes a hardware pre-processor based on a universal edge tracer and provides a perfect sync reconstruction based on a floating-point timer to advance the prior commercial 3DTV shutter glasses in terms of their power consumption. These two techniques enable an accurate sync reconstruction in the slow clock frequency of the synchronization timer and reduce the power consumption to less than about a maximum of 20% compared with other major commercial processors. This article describes the system's architecture and the details of the proposed techniques, also identifying the key concepts and functions.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.4
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• pp.77-84
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• 2004

Active control is regarded as one of the most efficient and economic countermeasures to reduce excessive vibration of ship superstructure. However, it is difficult to find its practical application in real ships in spite that many studies on such systems have been done. In this study, for the practical use of an active control system to reduce ship superstructure vibration, we have developed an active vibration compensator consisting of a mechanical actuator having compact size and expected lifetime over 20 years, its control panel including exclusive signal processing and computing board, sensors to detect phase and vibration, and its operation software providing various user-interface functions. From the performance verification test of the system at a 5,500 TEU container carrier, we have confirmed the system could reduce ship superstructure vibration of a harmonic component of main engine rotating frequency up to 0.1 mm/s.