• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5527-5545
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• 2019

Through-wall ultra-wide band (UWB) radar has been considered as one of the preferred and non-contact technologies for the targets detection owing to the better time resolution and stronger penetration. The high time resolution is a result of a larger of bandwidth of the employed UWB pulses from the radar system, which is a useful tool to separate multiple targets in complex environment. The article emphasised on human subject localization and detection. Human subject usually can be detected via extracting the weak respiratory signals of human subjects remotely. Meanwhile, the range between the detection object and radar is also acquired from the 2D range-frequency matrix. However, it is a challenging task to extract human respiratory signals owing to the low signal to clutter ratio. To improve the feasibility of human respiratory signals detection, a new method is developed via analysing the standard deviation based kurtosis of the collected pulses, which are modulated by human respiratory movements in slow time. The range between radar and the detection target is estimated using joint time-frequency analysis (JTFA) of the analysed characteristics, which provides a novel preliminary signature for life detection. The breathing rates are obtained using the proposed accumulation method in time and frequency domain, respectively. The proposed method is validated and proved numerically and experimentally.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.560-574
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• 2016

This paper presents a novel method for power system harmonic estimation based on the Park transform. The proposed method firstly extends the signal to a group of three-phase signals in a-b-c coordinate. Then, a linear fitting based method is adopted to estimate the fundamental frequency. Afterwards, the Park transform is utilized to convert the three-phase signals from a-b-c coordinate to d-q-0 coordinate. Finally, the amplitude and phase of a harmonic component of interest can be calculated using the d-axis and q-axis components obtained. Simulation studies have been conducted using matrix laboratory (MATLAB) and power system computer aided design/electromagnetic transients including direct current (PSCAD/EMTDC). Simulation studies in MATLAB have considered three scenarios, i.e., no-frequency-deviation scenario, frequency-deviation scenario and the scenario in the presence of inter-harminics. The results have demonstrated that the proposed method achieves very high accuracy in frequency, phase and amplitude estimation under noisy conditions, and suffers little influence of the inter-harmonics. Moreover, comparison studies have proved that the proposed method is superior to FFT and Interpolated FFT with the Hanning Window (IpFFTHW). Finally, a popular case in PSCAD/EMTDC has been employed to further verify the effectiveness of the proposed method.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.4
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• pp.102-108
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• 2015

According to various researches, one of main causes of flight accidents is influence of human factors. It is important to collect and analyze event data in advance to minimize and prevent human errors by developing safety checklist. As a result international aviation industry developed Flight Operations Quality Assurance for commercial airliners, and, upon its proven effectiveness, it is now highly recommended to adopt for helicopter operations. Consequently, S government organization instituted Helicopter Flight Operations Quality Assurance system in 2012. Hence, this study conducted regression analysis of S organization's flight event frequency and applied ICAO SMS Matrix to categorize the severity of the events according to international standards. Based on the analysis, this research derived fundamental checklist factors for helicopter, which can be a proactive measure for safe operation.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.170-181
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• 2012

The study on the analytical and productive methodolgy of visual culture contents is meaningful because cultural contents are regarded as a national growth industry. The fundamental notion of cultural contents is researched based on the notion of visual culture, and important factors of the fun are analyzed as a creative motive of visual culture contents. So this paper provides anaytical methodologies for the fun in visual culture contents, which are based on semiotic theories of Charles Morris, Roland Barthes and Roman Jakobson. These analytical matrix can be references for the study of the mechanism of fun and the basic theory for using fun effects in the visual culture contents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2303-2312
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• 1994

A high resolution algorithm is presented for resolving multiple narrowband plane waves that are incident on an equispaced linear array. To overcome the deleterious effects due to coherent sources, a number of noise-eigenvector-based approaches have been proposed for narrowband signal processing. For differing reasons, each f these methods provide a less than satisfactory resolution of the coherency problem. The proposed algorithm makes use of fundamental property possessed by those eigenvectors of the spatial covariance matrix that are associated with eigenvalues that are larger than the sensor noise level. This property is then used to solve the incoherent and coherent sources incident on an equispaced linear array. Simulation results are shown to illustrate the high resolution performance achieved with this new approach relative to that obtained with MUSIC and spatial smoothed MUSIC.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.229-244
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• 2015

H-infinity norm relates to the maximum in the frequency response function and H-infinity control method focuses on the case that the vibration is excited at the fundamental frequency, while 2-norm relates to the output energy of systems with the input of pulses or white noises and 2-norm control method weighs the overall vibration performance of systems. The trade-off between the performance in frequency-domain and that in time-domain may be achieved by integrating two indices in the mixed vibration control method. Based on the linear fractional state space representation in the modal space for a piezoelectric flexible structure with uncertain modal parameters and un-modeled residual high-frequency modes, a mixed dynamic output feedback control design method is proposed to suppress the structural vibration. Using the linear matrix inequality (LMI) technique, the initial populations are generated by the designing of robust control laws with different H-infinity performance indices before the robust 2-norm performance index of the closed-loop system is included in the fitness function of optimization. A flexible beam structure with a piezoelectric sensor and a piezoelectric actuator are used as the subject for numerical studies. Compared with the velocity feedback control method, the numerical simulation results show the effectiveness of the proposed method.

• Journal of Korean Association for Spatial Structures
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• v.3 no.1 s.7
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• pp.87-97
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• 2003

The structural system that discreterized from continuous shells is frequently used to make a large space structures. As well these structures show the unstable phenomena when a load level over the limit load, and snap-through and bifurcation are most well known of it. For the collapse mechanism, rise-span ratio, element stiffness and load mode are main factor, which it give an effect to unstable behavior. In our real situation, most structures have semi-rigid joint that has middle characteristic between pin and rigid joint. So the knowledge of semi-rigid joint is very important problem of stable large space structure. And the instability phenemena of framed space structures show a strong non-linearity and very sensitive behavior according to the joint rigidity For this reason In this study, we are investigating to unstable problem of framed structure with semi-rigidity and to grasp the nonlinear instability behavior that make the fundamental collapse mechanism of the large space frame structures with semi-rigid joint, by proposed the numerical analysis method. Using the incremental stiffness matrix in chapter 2, we study instability of space structures.

• Structural Engineering and Mechanics
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• v.11 no.4
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• pp.357-372
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• 2001

In this paper, cantilevered tall structures are treated as cantilever bars with varying cross-section for the analysis of their free longitudinal (or axial) vibrations. Using appropriate transformations, exact analytical solutions to determine the longitudinal natural frequencies and mode shapes for a one step non-uniform bar are derived by selecting suitable expressions, such as exponential functions, for the distributions of mass and axial stiffness. The frequency equation of a multi-step bar is established using the approach that combines the transfer matrix procedure or the recurrence formula and the closed-form solutions of one step bars, leading to a single frequency equation for any number of steps. The Ritz method is also applied to determine the natural frequencies and mode shapes in the vertical direction for cantilevered tall structures with variably distributed stiffness and mass. The formulae proposed in this paper are simple and convenient for engineering applications. Numerical example shows that the fundamental longitudinal natural frequency and mode shape of a 27-storey building determined by the proposed methods are in good agreement with the corresponding measured data. It is also shown that the selected expressions are suitable for describing the distributions of axial stiffness and mass of typical tall buildings.

• Journal of Information Display
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• v.6 no.4
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• pp.26-34
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• 2005

In this paper, a new rectification scheme to transform the uncalibrated stereo image pair into the calibrated one is suggested and its performance is analyzed by applying this scheme to the reconstruction of the intermediate views for multi-view stereoscopic display. In the proposed method, feature points are extracted from the stereo image pair by detecting the comers and similarities between each pixel of the stereo image pair. These detected feature points, are then used to extract moving vectors between the stereo image pair and the epipolar line. Finally, the input stereo image pair is rectified by matching the extracted epipolar line between the stereo image pair in the horizontal direction. Based on some experiments done on the synthesis of the intermediate views by using the calibrated stereo image pairs through the proposed rectification algorithm and the uncalibrated ones for three kinds of stereo image pairs; 'Man', 'Face' and 'Car', it is found that PSNRs of the intermediate views reconstructed from the calibrated images improved by about 2.5${\sim}$3.26 dB than those of the uncalibrated ones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.253-261
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• 2010

In this paper, the design and the fabrication of dual bandpass filter using heterogeneous resonators is presented. Each resonator would not have an effect on each resonant frequency. Two types of resonators are designed to have different fundamental resonant frequencies, one for the lower passband and the other for the upper passband. In the lower band, half and quarter wavelength resonators were used. In the upper band, a dual-mode resonator was used for adjusting bandwidth. In the upper pass band frequency, resonators of lower passband acts as the input and output. For WLAN, Proposed filters with different second passband frequencies at 2.45/5.2 GHz and 2.45/5.8 GHz are designed and fabricated.