• Kyungpook Mathematical Journal
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• v.55 no.4
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• pp.1053-1067
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• 2015

A two-direction multiscaling function ${\phi}$ satisfies a recursion relation that uses scaled and translated versions of both itself and its reverse. This offers a more general and flexible setting than standard one-direction wavelet theory. In this paper, we investigate how to find and normalize point values and derivative values of two-direction multiscaling and multiwavelet functions. Determination of point values is based on the eigenvalue approach. Normalization is based on normalizing conditions for the continuous moments of ${\phi}$. Examples for illustrating the general theory are given.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.226-229
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• 2001

The combined transmission lines with the underground power cables are continuously expanded in power systems. So the fault of combined transmission line is increased every year as the complication of underground transmission line. In this paper. traveling wave theory and DWT wavelet transform are used for fast and accurate detection of fault location at the combined transmission line. Traveling wave travels to each bus like surge and repeats reflection and transmission till transient signal is completely disappeared. When fault is occurred on overhead and underground tine, the fault location detecting algorithm was performed with using continuous peak value time-delay of traveling wave reflected from A bus.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.590-595
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• 2001

Vibration transient generated by developing localized fault in gear can be used as indicators of condition monitoring in a gear. In this paper, we propose the phase map for a fault signal using continuous wavelet transform to detect this vibration transient. Local fault induces the abrupt fluctuation of load exciting tooth and phase lag in the vibration signal measured on the gearbox. The relatively large fault like "tip breakage" easily can be detected by the clear fluctuation of exciting load. However, minor fault like "initial pitting" cannot be detected using the load fluctuation. To detect this kind of minor fault, the phase map for a fault signal is taken into account. The phase lag by minor fault is observed well in the phase map.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.97-103
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• 2006

A modified one-sided measurement technique is proposed for Rayleigh wave (R-wave) velocity measurement in concrete. The scattering from heterogeneity may affect the waveforms of R-waves in concrete, which may make the R-waves dispersive. Conventional one-sided techniques do not consider the scattering dispersion of R-waves in concrete. In this study, the maximum energy arrival concept is adopted to determine the wave velocity by employing its continuous wavelet transform. Experimental study was performed to show the effectiveness of the proposed method. The present method is applied to monitor the strength development of early-age concrete. A series of experiments were performed on early-age concrete specimens with various curing conditions. Results reveal that the proposed method can be effectively used to measure the R-wave velocity in concrete structures and to monitor the strength development of early-age concrete.

• Smart Structures and Systems
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• v.1 no.3
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• pp.257-266
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• 2005

In Lamb wave detection of damages in smart structures, the excitation pulse is usually designed as a narrow band burst wave for the convenience of analysis and recognition. However, the wideband excitation can excite more modes in plate/shell structure and thus provides extra information for changes of the structure. This paper presents a method that can extract information in wideband Lamb wave signals. By transforming the detected signals into various sub-frequency band, the measured signal can be converted to its equivalences of narrow band excitations, therefore, the information in different frequency bands can be acquired from a single test and in the same time the complicity of wideband signal can be simplified. Some test results are provided to verify this method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5D
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• pp.483-492
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• 2012

The early setting time of concrete is an important factor determining the slip up velocity of the slip-form system. Accordingly, need is for a technique evaluating the early setting time in order to secure the safety of the slip-form system and the construction quality of concrete. This paper intends to estimate the early setting time by evaluating the setting degree of concrete using surface wave velocity so as to determine the slip up time of the slip-form system. Penetration resistance test and compressive strength test are performed first to clarify the relationship between the early setting time of concrete and the compressive strength. Then, compressive strength test and ultrasonic wave test are conducted to examine the relation between the compressive strength and the surface wave velocity. Continuous wavelet transform is adopted to measure the surface wave velocity. Numerical analysis is carried out to demonstrate the appropriateness of the application of continuous wavelet transform. Based on these results, the propagation velocity of the surface wave required for the slip up of slip-form system is suggested. Finally, a reduced model test of the slip-form system is conducted to verify the feasibility of the proposed surface wave velocity for the determination of th slip up velocity.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.700-702
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• 2003

A new method for automatic detection of absorption features is proposed. This method is based on the modulus maximum of the scale-space image calculated by continuous wavelet transform. This method is computationally efficient as compared to traditional methods. The continuum removal algorithm is than implemented on the detected absorption features to reduce some additive factors caused by other absorbing of materials. The results show that the chlorophyll absorption features are detected exactly.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.29-36
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• 2009

The analysis of Radar signal, telecommunication, bioengineering, seismic, and acoustic signal is consist of the Non-stationary signal which has non-linear phase variation. Non-stationary signal means that the physical properties of signal depend on time variation and the instantaneous frequency represents physical property of these type of signal. Thus estimation of the instantaneous frequency of non-stationary signal is important subject in signal processing. In this work, the instantaneous frequency analysis method utilizing continuous wavelets transform is represented and compared with Hilbert Transform method.

• Journal of KIISE:Software and Applications
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• v.37 no.9
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• pp.712-721
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• 2010

This paper proposes a new fire-flame detection method using probabilistic membership function of visual features and Fuzzy Finite Automata (FFA). First, moving regions are detected by analyzing the background subtraction and candidate flame regions then identified by applying flame color models. Since flame regions generally have continuous and an irregular pattern continuously, membership functions of variance of intensity, wavelet energy and motion orientation are generated and applied to FFA. Since FFA combines the capabilities of automata with fuzzy logic, it not only provides a systemic approach to handle uncertainty in computational systems, but also can handle continuous spaces. The proposed algorithm is successfully applied to various fire videos and shows a better detection performance when compared with other methods.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2485-2492
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• 2018

The rapid development of large-scale integrated circuits has brought great challenges to the circuit testing and diagnosis, and due to the lack of exact fault models, inaccurate analog components tolerance, and some nonlinear factors, the analog circuit fault diagnosis is still regarded as an extremely difficult problem. To cope with the problem that it's difficult to extract fault features effectively from masses of original data of the nonlinear continuous analog circuit output signal, a novel approach of feature extraction and dimension reduction for analog circuit fault diagnosis based on wavelet packet decomposition, local linear embedding algorithm, and clone selection algorithm (WPD-LLE-CSA) is proposed. The proposed method can identify faulty components in complicated analog circuits with a high accuracy above 99%. Compared with the existing feature extraction methods, the proposed method can significantly reduce the quantity of features with less time spent under the premise of maintaining a high level of diagnosing rate, and also the ratio of dimensionality reduction was discussed. Several groups of experiments are conducted to demonstrate the efficiency of the proposed method.