• Journal of the Institute of Electronics Engineers of Korea SC
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• 제48권2호
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• pp.40-46
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• 2011

This paper proposes a real-time face detection and tracking system that uses neural oscillators which can be applied to access regulation system or control systems of user authentication as well as a new algorithm. We study a way to track faces using the neural oscillatory network which imitates the artificial neural net of information handing ability of human and animals, and biological movement characteristic of a singular neuron. The system that is suggested in this paper can broadly be broken into two stages of process. The first stage is the process of face extraction, which involves the acquisition of real-time RGB24bit color video delivering with the use of a cheap webcam. LEGION(Locally Excitatory Globally Inhibitory)algorithm is suggested as the face extraction method to be preceded for face tracking. The second stage is a method for face tracking by discovering the leader neuron that has the greatest connection strength amongst neighbor neuron of extracted face area. Along with the suggested method, the necessary element of face track such as stability as well as scale problem can be resolved.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제12권8호
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• pp.3398-3405
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• 2011

Vibration intensity (VI) method is used to reduce sound source generated from air-conditioning rotary compressor. Generally VI method is a good tool to find a sound source through vibration power flow. In this paper, the vibrations are measured by using the 3 uni-axial accelerometer from both the shells of the normal compressor and the fault compressor. The VI method successfully found out the sound source position on the surface of the compressor. In addition, the main noise (3kHz ~ 6.3kHz) was deminished by applying the newly designed compressor inner part which is related to the orginal noise source.

• Journal of the Korean Society for Nondestructive Testing
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• 제36권6호
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• pp.496-503
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• 2016

Leakages at plant structures of power and petrochemistry plants have led to casualties and economic losses. These leakages are caused by fatigue failure of pipelines and their wall thickness. Vibration measurement methods for plant pipelines mainly use acceleration and laser sensors. These sensors are difficult to install and operate and thus lead to an increase in operational cost especially for wide area surveillance. Recently, measurements of leak and vibration displacements using cameras have attracted the interest of many researchers. This method has advantages such as simple installation, long distance monitoring, and wide area surveillance. Therefore, in this paper, we have developed a system that can measure the leakage and vibrational displacement by using a camera. Furthermore, the developed system was verified with experimental data.

• Journal of the Korea institute for structural maintenance and inspection
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• 제17권1호
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• pp.124-132
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• 2013

Damage location and extent could be detected by the inverse analysis on dynamic response of the damaged structure. In general, detection of damage location is possible by the observation of the mode shape difference between undamaged and damaged structure and assessment of stiffness reduction is possible by the observation of the natural frequency difference of them. The study on damage detection by the dynamic response in civil structures is reported enough and in practical use, but in building structures it is reported seldom due to several problems. The purpose of this study is to present the damage detection method on shear building structures by mode shape. The damage location index using 1st mode shape is observed theoretically to find out damage location. The damage detection method is applied to numerical analysis model such as MATLAB and MIDAS GENw for the verification. Finally the shaking table test on 3 story shear building is performed for the examination of the damage detection method. In shaking table results, as the story stiffness decrease by 25% the 1st mode frequency increase by 12%, and the damage location index represents minus at damaged story.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제17권9호
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• pp.709-717
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• 2016

In this study, the convenience and efficiency of vision-based displacement measurement (VBDM) to estimate the cable tension of cable-stayed bridges and the requirements for its effective application were examined. To demonstrate its convenience and efficiency, it was confirmed that VBDM can be accomplished with a minimum amount of equipment using a commercial camcorder. In this case, it was found that the accuracy of estimation of the natural frequencies is sufficient, even though magnitude errors can occur when conducting high-speed recording at the low resolution afforded by the minimal equipment employed. It was also confirmed that the most important factor in detecting the precise natural frequencies is the use of the appropriate frequency range in the tension estimation using vibration. Based on these results, a study was carried out on the accuracy variation of the estimated tension according to the frame rate of a commercial camcorder. For this purpose, an experiment was performed to estimate the cable tension in a cable-stayed bridge model. Through this experiment, the detectable tensions of cables with various natural frequencies as a function of the frame rate were summarized. As a result, it was shown that the frame rate should be determined based on the natural frequency which is estimated to be located within the appropriate frequency range (approximately 10~75% of theoretical range) considering the aliasing and low-frequency distortion due to excitations.

• Transactions of the Korean Society of Mechanical Engineers
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• 제9권6호
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• pp.691-698
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• 1985

This paper presents a method for the identification of vibration sources in a multiple input system where the input source may be coherent with each other. Using multi-dimensional spectral analysis, it is found that one of the most significant vibration sources of a gasoline engine is the pressure variation within the cylinder. In this analysis the concepts of residual spectral analysis and the partial coherence function are applied. Finally, the overall levels of the acceleration on the cylinder block obtained by multi-dimensional spectral analysis are compared with those by the frequency response function approach. The experimental results have shown a good agreement with the results calculated by this method the input sources are coherent strongly each other.

• Membrane Journal
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• 제14권2호
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• pp.142-148
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• 2004

This paper presents the enhancement of oxygen transfer efficiency using vibrating intravascular lung assist device (VIVLAD) for patients having chronic respiratory problems. The flow rate was controlled by the pump and monitored by a built-in flow meter. The vibration apparatus was composed of a piezo-actuator, a function generator, and a power amplifier. Gas flow rates of up to 6 L/min through the 120-cm-long hollow fibers have been achieved by exciting a piezo-actuator. The output PVDF sensor and FRF (frequency response function) were investigated by various frequency in VIVLAD. As a result, the maximum oxygen transfer rate was found to occur with maximum amplitude and the transfer of vibration to the hollow fiber membranes. It was excited by the frequency band of 35 Hz at various distilled water flow rates, and various module types.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제16권4호
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• pp.404-413
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• 2006

Induction motors are the workhorse of our industry because of their versatility and robustness. The diagnosis of mechanical load and power transmission system failures is usually carried out through mechanical signals such as vibration signatures, acoustic emissions, motor speed envelope. The motor faults including mechanical rotor imbalances, broken rotor bar, bearing failure and eccentricities problems are reflected in electric, electromagnetic and mechanical quantities. The recent research has been directed toward electrical monitoring of the motor with emphasis on inspecting the stator current of the motor, The stator current spectrum has been widely used for fault detection in induction motor systems. The motor current signature analysis is the useful technique to assess machine electrical condition. This paper describes the motor condition detected by the current signatures Paralleled with vibration signatures analysis of induction motors with the roller bearing and the journal bearing type for large vertical pumps in power plant as examples to discuss for motor fault detection and diagnosis.

• Korean Journal of Optics and Photonics
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• 제14권3호
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• pp.260-265
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• 2003

A noncontact optical system that can measure displacement or vibration of an object is designed by employing the oblique ray method. By using a single convex lens which serves as both the input and output lenses, we made the optical system very compact and reliable. In addition, the bandwidth of the vibration measurement is more than 100 KHz by using the position-sensitive detector as the beam position sensor. The resolution and capture range of the system are $\pm$1 ${\mu}{\textrm}{m}$ and 1100 ${\mu}{\textrm}{m}$, respectively. As a sample test, the vibrations of a speaker and a rotating compact disc surface were measured.

• Journal of Aerospace System Engineering
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• 제18권3호
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• pp.65-69
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• 2024

This study aimed to analyze the structural integrity of a sensor control box, a critical component for real-time monitoring of brake chamber pressure in large commercial vehicles and trailers. We utilized the computational analysis program ANSYS Workbench R2021 based on our testing conditions and vibration test specification KS R1034. Through modal analysis, we identified resonance frequencies within the frequency range of 5 Hz to 100 Hz and compared results in the frequency range of 33 Hz to 67 Hz using harmonic analysis.