• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2299-2318
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• 2019

Location-aware networks are of great importance for both civil lives and military applications. Methods based on line-of-sight (LOS) measurements suffer sever performance loss in harsh environments such as indoor scenarios, where sensors can receive both LOS and non-line-of-sight (NLOS) measurements. In this paper, we propose a data association (DA) process based on the expectation maximization (EM) algorithm, which enables us to exploit multipath components (MPCs). By setting the mapping relationship between the measurements and scatters as a latent variable, coefficients of the Gaussian mixture model are estimated. Moreover, considering the misalignment of sensor position, we propose a space-alternating generalized expectation maximization (SAGE)-based algorithms to jointly update the target localization and sensor position information. A two dimensional (2-D) circularly symmetric Gaussian distribution is employed to approximate the probability density function of the sensor's position uncertainty via the minimization of the Kullback-Leibler divergence (KLD), which enables us to calculate the expectation step with low computational complexity. Moreover, a distributed implementation is derived based on the average consensus method to improve the scalability of the proposed algorithm. Simulation results demonstrate that the proposed centralized and distributed algorithms can perform close to the Monte Carlo-based method with much lower communication overhead and computational complexity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.91-96
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• 2019

There are so many low power MAC protocols for wireless sensor network. IEEE802.15.4 among them has disadvantage of a large power consumption for synchronization. To save power consumption it use the superframe operation alternating sleep mode and awake mode. But latency is longer result from superframe operation. Typical asynchronous B-MAC can have shorter latency according to check interval. But transmitter consumes more power because of long preamble. And receiver is suffering from overhearing. In this paper, we propose the adaptive check interval scheme of B-MAC for enhancing the power consumption and delay latency performance. Its power consumption is evaluated by comparing the proposed scheme with a typical IEEE802.15.4.

• Journal of the Korean earth science society
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• v.40 no.4
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• pp.428-435
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• 2019

In the shallow coastal area, located off the northwestern Taean Peninsula of the eastern Yellow Sea, geoacoustic models with two layers were reconstructed for underwater acoustic experimentation and modeling. The Yellow Sea experienced glacio-eustasy sea-level fluctuations during Quaternary period. Coastal sedimentation in the Yellow Sea was characterized by alternating terrestrial and shallow marine deposits that reflected the fluctuating sea levels. The coastal geoacoustic models were based on data from piston, grab cores and the high-resolution 3.5 kHz, chirp seismic profiles (about 70 line-kilometers, respectively). Geoacoustic data of the cores were extrapolated down to 3 m in depth for geoacoustic models. The geoacoustic property of seafloor sediments is considered a key parameter for modeling underwater acoustic environments. For simulating actual underwater environments, the P-wave speed of the models was adjusted to in-situ depth below the sea floor using the Hamilton method. The proposed geoacoustic models could be used for submarine acoustic inversion and modeling in shallow-water environments of the study area.

• PNF and Movement
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• v.16 no.3
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• pp.475-484
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• 2018

Purpose: The aim of the present study was to investigate the effect of a PNF orofacial exercise program on diadochokinesis in subacute stroke patients with dysarthria. Methods: Thirteen subacute stroke inpatients with dysarthria were recruited for the study. All participants were randomly assigned to two groups: an experimental group (n=7) and a control group (n=6). The experimental group performed a PNF orofacial exercise program, and the control group carried out an orofacial self-exercise. Both groups received the treatments 30 minutes per day, 5 days per week, for 4 weeks. The outcome measures were assessed before and after the intervention, including an alternating motion rate (AMR) and sequential motion rate for diadochokinesis. Results: After the intervention, both groups showed significant improvement in diadochokinesis (p<0.05). In the change values for both groups, the experimental group showed a more significant improvement than the control group did in /pə/ of AMR (p<0.05). Conclusion: These findings suggest that PNF orofacial exercise programs may have positive effects on the improvement of diadochokinesis in subacute stroke patients with dysarthria.

• Journal of Power Electronics
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• v.19 no.1
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• pp.179-189
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• 2019

Four-quadrant converters (4QCs) are widely used as AC-DC power conversion interfaces in many areas. A control delay commonly exists in the digital implementation process of 4QCs, especially for high power 4QCs with a low switching frequency. This usually results in alternating current distortion, increased current harmonic content and system instability. In this paper, the control delay is divided into a computation delay and a PWM delay. The impact of the control delay on the performance of a 4QC is briefly analyzed. To obtain a fundamental value of AC current that is as accurately as possible, a specific sampling method considering the PWM pattern is introduced. Then a current predictive control based on a modified z-transform is proposed, which is effective in reducing the control delay and easy in terms of digital implementation. In addition, it does not depend on object models and parameters. The feasibility and effectiveness of the proposed predictive current control method is verified by simulation and experimental results.

• Journal of the Semiconductor & Display Technology
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• v.16 no.2
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• pp.44-48
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• 2017

We explain optical and electrical properties of top and bottom-emission structured alternating-current powder electroluminescent devices (ACPELDs) with Ga-doped ZnO(GZO) transparent electrode. The top-emission ACPELDs were layered as the metal electrode/dielectric layer/emission layer/top transparent electrode and the bottom-emission ACPELDs were structured as the bottom transparent electrode/emission layer/dielectric layer/metal electrode. The yellow-emitting ZnS:Mn, Cu phosphor and the barium titanate dielectric layers were layered through the screen printing method. The GZO transparent electrode was deposited by the sputtering, its sheet resistivity is $275{\Omega}/{\Box}$. The transparency at the yellow EL peak was 98 % for GZO. Regardless of EL structures, EL spectra of ACPELDs were exponentially increased with increasing voltages and they were linearly increased with increasing frequencies. It suggests that the EL mechanism was attributed to the impact ionization by charges injected from the interface between emitting phosphor layer and the transparent electrode. The top-emission structure obtained higher EL intensity than the bottom-structure. In addition, charge densities for sinusoidal applied voltages were measured through Sawyer-Tower method.

• Journal of English Language & Literature
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• v.55 no.6
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• pp.993-1011
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• 2009

Generally, the parts narrated by Esther in Bleak House has been considered less convincing and reliable than those by the anonymous narrator for some problematic qualities in her character and narration. However, Esther's narrative shows Dickens' masterly depiction of emotional deprivation, the psychic consequences of the Victorian sexual repression on its victim. Therefore, to restore the reliability of Esther's narrative is the prerequisite for claiming its value as an appropriate locus of the meanings of the text. On the other hand, the anonymous narrator is not so omniscient as he has been regarded. As the chapters proceed, his omniscient power and authority is conspicuously weakened, and even transferred to other characters such as Esther and Mr. Bucket. This shows that the identity of the omniscient voice is unstable and that Dickens does not intend his voice to be the sole center of meanings of the text. In short, these two narratives are the necessary partners in imagining and understanding the society in its wholeness. Alternating and sometimes intersecting each other throughout the novel, these opposing viewpoints make us see the contradictory multi-leveledness of the Victorian society. The equality of them implies Dickens' notion that more than single unified voice is needed to portray ideological conflicts of his age.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.49-54
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• 2021

Relative to the outer surface of the mastic coating, the reliability of the available waterproofing resource is determined by the ability to stabilize the structural characteristics in difficult climatic conditions. Organic components of mastic as a result of solar radiation, elevated temperatures and their alternating change, atmospheric oxidants, especially in industrial areas, have a tendency to self-polymerization and loss of low molecular weight components. This is the gradual loss of deformability and the transition to brittleness with its tendency to crack as the reasons for the gradual transition from normal to emergency operating condition.The presented mechanism of functioning of the coating surface indicates the expediency of increasing its components, able to stabilize the structure and prevent changes in deformability.Durability, hydrophobicity, water displacement, water absorption are accepted as estimating indicators. The main dependences of the influence of the lost additional components of mastic on the operational properties of the formed coating characterize the ability to provide successful resistance to environmental influences and longer stability. As a result, mastic acquires additional service life.

• ETRI Journal
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• v.42 no.6
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• pp.922-931
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• 2020

A hierarchical iterative algorithm for the canonical polyadic decomposition (CPD) of tensors is proposed by improving the traditional conjugate gradient least squares (CGLS) method. Methods based on algebraic operations are investigated with the objective of estimating the direction of arrival (DoA) and polarization parameters of signals impinging on an array with electromagnetic (EM) vector-sensors. The proposed algorithm adopts a hierarchical iterative strategy, which enables the algorithm to obtain a fast recovery for the highly collinear factor matrix. Moreover, considering the same accuracy threshold, the proposed algorithm can achieve faster convergence compared with the alternating least squares (ALS) algorithm wherein the highly collinear factor matrix is absent. The results reveal that the proposed algorithm can achieve better performance under the condition of fewer snapshots, compared with the ALS-based algorithm and the algorithm based on generalized eigenvalue decomposition (GEVD). Furthermore, with regard to an array with a small number of sensors, the observed advantage in estimating the DoA and polarization parameters of the signal is notable.

• ETRI Journal
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• v.43 no.1
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• pp.120-132
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• 2021

A frequency diverse array (FDA) multiple-input multiple-output (MIMO) radar employs a small frequency increment across transmit elements to produce an angle-range-dependent beampattern for target angle and range detection. The joint angle and range estimation problem is a trilinear model. The traditional trilinear alternating least square (TALS) algorithm involves high computational load due to excessive iterations. We propose a fast-convergence trilinear decomposition (FC-TD) algorithm to jointly estimate FDA-MIMO radar target angle and range. We first use a propagator method to obtain coarse angle and range estimates in the data domain. Next, the coarse estimates are used as initialized parameters instead of the traditional TALS algorithm random initialization to reduce iterations and accelerate convergence. Finally, fine angle and range estimates are derived and automatically paired. Compared to the traditional TALS algorithm, the proposed FC-TD algorithm has lower computational complexity with no estimation performance degradation. Moreover, Cramer-Rao bounds are presented and simulation results are provided to validate the proposed FC-TD algorithm effectiveness.