• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.3
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• pp.116-122
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• 2006

The underground transmission lines is continuously expanded in power systems. Therefore the fault of underground transmission lines are increased every year because of the complication of systems. However the studies dealing with fault location in the case of the underground transmission lines are rarely reported except for few papers using traveling wave method and calculating underground cable impedance. This paper describes the algorithm using fuzzy system and travelling wave method in the underground transmission line. Fuzzy inference is used for fault discrimination. To organize fuzzy algorithm, it is important to select target data reflecting various underground transmission line transient states. These data are made of voltage and average of RMS value on zero sequence current within one cycle after fault occurrence. Travelling wave based on wavelet transform is used for fault location. In this paper, a variety of underground transmission line transient states are simulated by EMTP/ATPDraw and Matlab. The input which is used to fault location algorithm are Detail 1(D1) coefficients of differential current. D1 coefficients are obtained by wavelet transform. As a result of applying the fuzzy inference and travelling wave based on wavelet transform, fault discrimination is correctly distinguished within 1/2 cycle after fault occurrence and fault location is comparatively correct.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2159-2164
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• 2008

Ubiquitous healthcare system is system that monitors and manages user's health information, and most important in the healthcare system is accuracy of the measured health data. But, the accuracy changes remarkably according to user's motion artifacts in real life. To elevate accuracy of health data, we proposed new algorithm to detect maximum point of pulse wave for heart rate extraction. and the proposed algorithm is to detect maximum points detect of pulse wave in photo-plethysmography signal included motion artifacts by fuzzy inference and multi sub-band filters. In results of experiment to evaluate the performance of the proposed algorithm, we could verify the proposed algorithm extracted maximum point of pulse wave in complex motion artifacts.

• Journal of Biomedical Engineering Research
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• v.17 no.2
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• pp.235-240
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• 1996

The automated ECG diagnostic systems that are odd in hospitals have low performance of P-wave detection when faced with some diseases such as conduction block. So, the purpose of this study was the improvement of detection performance in conduction block which is low in P-wave detection. The first procedure was removal of baseline drift by subtracting the median filtered signal of 0.4 second length from the original signal. Then the algorithm detected R peak and T end point and cancelled the QRS-T complex to get'p prototypes'. Next step was magnification of P prototypes with dispersion and detection of'p candidates'in the magnified signal, and then extraction of contextual information concerned with P-waves. For the last procedure, the CIR was applied to P candidates to confirm P-waves. The rule base consisted of three rules that discriminate and confirm P-waves. This algorithm was evaluated using 500 patient's raw data P-wave detection perFormance was in- creased 6.8% compared with the QRS-T complex cancellation method without application of the rule base.

• Current Optics and Photonics
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• v.2 no.6
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• pp.612-622
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• 2018

In wave-front-sensor-less adaptive optics (WFS-less AO) systems, the Jacopo Antonello (JA) method belongs to the model-based class and requires few iterations to achieve acceptable distortion correction. However, this method needs a lot of measurements, especially when it deals with moderate or severe aberration, which is undesired in free-space optical communication (FSOC). On the contrary, the stochastic parallel gradient descent (SPGD) algorithm only requires three time measurements in each iteration, and is widely applied in WFS-less AO systems, even though plenty of iterations are necessary. For better and faster compensation, we propose a WFS-less hybrid approach, borrowing from the JA method to compensate for low-order wave front and from the SPGD algorithm to compensate for residual low-order wave front and high-order wave front. The correction results for this proposed method are provided by simulations to show its superior performance, through comparison of both the Strehl ratio and the convergence speed of the WFS-less hybrid approach to those of the JA method and SPGD algorithm.

• Steel and Composite Structures
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• v.19 no.1
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• pp.131-152
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• 2015

Easy detection and evaluation of defect in the tube structure is a continuous problem and remains a significant demand in tube inspection technologies. This study is aimed to automate defect detection using the pattern recognition approach based on the classification of high frequency stress wave signals. The stress wave signals from vibrational impact excitation on several tube conditions were captured to identify the defect in ASTM A179 seamless steel tubes. The variation in stress wave propagation was captured by a high frequency sensor. Stress wave signals from four tubes with artificial defects of different depths and one reference tube were classified using the autoregressive (AR) algorithm. The results were demonstrated using a dendrogram. The preliminary research revealed the natural arrangement of stress wave signals were grouped into two clusters. The stress wave signals from the healthy tube were grouped together in one cluster and the signals from the defective tubes were classified in another cluster. This approach was effective in separating different stress wave signals and allowed quicker and easier defect identification and interpretation in steel tubes.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.582-589
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• 2006

Shear wane velocity is important property for grasping the dynamic characteristics of material. It is has been used in various fields such as non-destructive testings of structures, seismic analysis of geotechnical structures and maintenance of concrete structure, and etc. Usually, shear wave velocities of rock cores and concrete cylinders are determined by free-free resonance tests, Shear wave measurement in free-free resonance tests is not straightforward, as compared with rod wave and flexural wane measurements. In This study, a new technique using resonance features of flexural and shear waves were proposed in which the nodal points for the fundamental mode of flexural waves were employed to generate and measure the shear waves with the flexural waves minimized. The real measurements for aluminum cylinders proved validity and reliability of the proposed algorithm. In addition to the proposed algorithm, the effects of material properties on elastic-wave velocities in resonance measurements were also studied. In summary, a new framework of the resonance measurements for shear-wave velocity determination was established, based on the results of this thesis.

• ETRI Journal
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• v.35 no.1
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• pp.120-130
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• 2013

This paper presents an analysis of resource assignment for multihop communications in millimeter-wave (mm-wave) wireless personal area networks. The purpose of this paper is to figure out the effect of using directional antennas and relaying devices (DEVs) in communications. The analysis is performed based on a grouping algorithm, categorization of the flows, and the relaying DEV selection policy. Three schemes are compared: direct and relaying concurrent transmission (DRCT), direct concurrent transmission (DCT), and direct nonconcurrent transmission (DNCT). Numerical results show that DRCT is better than DCT and DCT is better than DNCT for any antenna beamwidths under the proposed algorithm and policy. The results also show that using relaying DEVs increases the throughput up to 30% and that there is an optimal beamwidth that maximizes spatial reuse and depends on parameters such as the number of flows in the networks. This analysis can provide guidelines for improving the performance of mm-wave band communications with relaying DEVs.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.62-67
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• 2005

A new picking algorithm has been developed on real-time basis for finding the onset of P wave as well as discriminating the micro seismic signal from artificial noise. Unlike the previous methods which have used the STA/LTA ratio for discriminating the P arrivals, we have adopted the slope discrimination methods for identifying the P onset. As result, this algorithm has been turned out to be efficient in both accuracy and computation in on-line system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.730-734
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• 2003

A beamforming method is a kind of spatial filter that focus the amy's signal capturing abilities in a desired direction. In this paper, we detect the location of a source under reflective condition using the multi-dimensional MUSIC algorithm then, we can iud the image source locations from the experimental geometry, and we reconstruct the partial fields for direct wave and reflected wave by using Adaptive nulling algorithm. Numerical simulations are performed to verify its performance under various conditions.

• Journal of the Korean Geotechnical Society
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• v.28 no.8
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• pp.55-63
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• 2012

The evaluation of shear modulus (or shear wave velocity) profile of the site is very important in various fields of geotechnical engineering and various surface wave methods have applied to determine the shear wave velocity profiles and showed good performance. Surface wave methods evaluate the dispersion curve in the field and determine the shear wave velocity profile through the inversion process. In this paper, the automated inversion process using the genetic algorithm is developed for HWAW method which is one of surface wave methods recently developed. The proposed method uses the error function based on the wavelength domain dispersion curve and can determine the reliable shear wave velocity profile not only in shallow depth but also in deep depth. To estimate the validity of the proposed method, numerical simulations and field test were performed and the proposed method was applied to determine the shear wave velocity profiles. Through the numerical simulations and field applications, the promising potential of the proposed method was verified.