• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.4
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• pp.346-352
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• 1982

The vibration characteristics of hyoid gears are experimentally investigated with backlash and tooth mesh frequency varied. Experiments are performed with two types of gear sets; well-machined and over-lapped gears. Through the experimental works, a constant torque 0.8kg.m is applied to th gears and a pulse type of trigger signal synchronizing tooth contact is used to measure the tooth mesh frequency and to average the gear vibration signal in the time domain. The time averaged vibration signals are frequency analyzed by a digital signal analyzer. The experimental results show the vibration characteristics of the two different types of gears in relation to backlash amount and mesh frequency variations are well differentiated by harmonic amplitudes and their ratios, and peak-to-peak amplitude of the gear vibration.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.944-949
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• 1986

By improving the ability of arithmatic processing with an arithmatic processor in a microcomputer and realizing the data input system for real time analysis, an FFT analyzer that is usable within the range of audio frequency is designed and constructed. The input signal passes through a gain programmable pre-amplifier and anti-aliasing lowpass filter into an analogditital converter to be converted into digital form. The converted input data is processed by an Apple II microcomputer. The results of the processing are displayed using a microcomputer display unit and can be copied on a printer or stored in a floppy disk.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.342-349
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• 2019

We describe and anlayzes the methodology and implementation results of H / W configuration and signal characteristics analysis algorithm for analyzing equipment for analyzing OFDMA physical layer based on 802.16e. Recently, demand for signal analysis of instruments that analyze these signals with the development of digital communication signals is rapidly increasing. Accordingly, it is necessary to develop signal analysis equipment capable of analyzing characteristics of a broadband communication signal using a wideband digital signal processing module. In this paper, we have studied the basic theory of OFDMA in order to devise a device capable of analyzing characterisitcs of broadband communication signals. Second, the structure of OFDMA transmitter/receiver was examined. Third, a wideband digitizer was implemented. we design Wimax signal analysis algorithm based on OFDMA among broadband communication methods and propose Wimax physical layer analysis S/W implementation through I, Q signals. The IF downconverter used the receiver module and the LO generation module of the spectrum analyzer. Quantitative analysis result is obtained through the algorithm of Wimax signal analysis by I, Q data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.8
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• pp.24-33
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• 2002

For mixed signal circuits that integrate both analog and digital blocks onto the same chip, testing the mixed circuits has become the bottleneck. Since most of mixed signal circuits are functionally tested, mixed signal testing needs expensive automatic test equipments for test input generation and response acquisition. In this paper, a new efficient BIST is developed which can be used for mixed signal circuits. In the new BIST, only faults on embedded resistances, capacitances and its combinations are considered. To guarantee the quality of chips, the new BIST performs both voltage testing and phase testing. Using these two testing modes, all the faults are detected. In order to support this technique, the voltage detector and the phase detector are developed. Experimental results prove the efficiency of the new BIST.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1189-1194
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• 2002

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent micrphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidally have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional r]n analyzer will show distorted value. In this paper the expression of the Fourier transformed data of a harmonic signal is formulated when there is leakage error. The method to elimate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.449-455
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• 2009

In this paper, we developed a digital gait analyzer using the triaxial accelerometer(TA). An approach for normal gait detection employing decay slope peak detection(DSPD) algorithm was presented. The TA was attached to the center of the waist of a subject. The subject walked a bare floor at 60, 92 and 120 steps/minute. We analyzed vertical axis acceleration signal for gait detection. At 60, 92, 120 steps/minute walking, detection accuracy of gait events were over 99 % accuracy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1156-1161
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• 2001

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent microphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidally have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional FFT analyzer will show distorted value. In this paper, the expression of the Fourier transformed date of a harmonic signal with a single frequency is formated when there is leakage error. The method to elimate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• Smart Structures and Systems
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• v.4 no.3
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• pp.305-318
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• 2008

The development of a digital signal processor based prototype is described in relation to continuing efforts for realizing a fully self-contained active sensor system utilizing impedance-based structural health monitoring. The impedance method utilizes a piezoelectric material bonded to the structure under observation to act as both an actuator and sensor. By monitoring the electrical impedance of the piezoelectric material, insights into the health of the structured can be inferred. The active sensing system detailed in this paper interrogates a structure utilizing a self-sensing actuator and a low cost impedance method. Here, all the data processing, storage, and analysis is performed at the sensor location. A wireless transmitter is used to communicate the current status of the structure. With this new low cost, field deployable impedance analyzer, reliance on traditional expensive, bulky, and power consuming impedance analyzers is no longer necessary. A complete power analysis of the prototype is performed to determine the validity of power harvesting being utilized for self-containment of the hardware. Experimental validation of the prototype on a representative structure is also performed and compared to traditional methods of damage detection.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.345-350
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• 2003

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent microphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidably have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional FFT analyzer will show distorted value. In this paper, the expression of the Fourier transformed data of a harmonic signal with a single frequency is formulated when there is leakage error. The method to eliminate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.145-150
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• 2011

This study was developed the posture balance system of multi-parameter for moving body after and before exercising. Body transition meaned a head moving and upper body moving. This system has catched a signal for physical condition of body data such as a data acquisition system, data signal processing and feedback system. There were checked a parameter that measured vision, vestibular, somatosensory, CNS. This system was evaluated a data through the stability. The posture balance system can be used to support assessment for body moving in exercising situation. It was expected to monitor a physical parameter for health management system.