• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.310-315
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• 2002

The Bark Coherence Function (BCF) defies a coherence function within perceptual domain as a new cognition module, robust to linear distortions due to the analog interface of digital mobile system. Our previous experiments have shown the superiority of BCF over current measures. In this paper, a new BCF suitable for VoIP is developed. The unproved BCF is based on the wavelet series expansion that provides good frequency resolution while keeping good time locality. The proposed Wavelet based Bark Coherence function (WBCF) is robust to variable delay often observed in packet-based telephony such as Voice over Internet Protocol (VoIP). We also show that the refinement of time synchronization after signal decomposition can improve the performance of the WBCF. The regression analysis was performed with VoIP speech data. The correlation coefficients and the standard error of estimates computed using the WBCF showed noticeable improvement over the Perceptual Speech Quality Measure (PSQM) that is recommended by ITU-T.

• Education of Primary School Mathematics
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• v.23 no.4
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• pp.229-255
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• 2020

In this study, considering the OECD's DeSeCo and 2030 projects, the curriculum to develop competency was expected to be more emphasized, and the evaluation standards of the 2015 revised mathematics curriculum for elementary school in Korea and the Australian curriculum were analyzed in depth. To this end, the capabilities newly emphasized in the OECD 2030 Project were examined in detail and examined how the Australian elementary school mathematics curriculum included capabilities in achievement standards and content descriptions. The achievement standards of elementary school mathematics curriculum in Korea and Australia were matched, and the contents of number and arithmetic domain were compared and analyzed, and the skill verbs included in the achievement standards were analyzed and compared to see how their competencies were reflected in the achievement standards. Based on the results of the analysis, implications for improving math achievement standards were derived to faithfully reflect the capabilities into the mathematics curriculum.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.436-436
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• 2011

Recently, spintronic devices with submicron structures are widely investigated to take advantage of their unique micromagnetic properties. In this work, we study the temperature dependence of exchange bias in bilayer anti-dot arrays made by depositing Co (40 nm)/Ni (5 nm) ferromagnetic bilayer on Si substrate to form anti-dot arrays with a diameter $1{\mu}m$. The anti-dot patterning was done only for the upper Co layer, while the Ni underlayer was kept unperforated. The temperature dependences of magnetoresistance (MR) and exchange bias were studied along magnetic easy and hard axes. The in-plane MR measurements were performed using a physical-property measurement system (PPMS ; Quantum Design Inc.) at various temperatures. The standard in-line four-point probe configuration was used for the electrical contacts. As temperature was varied, the MR data were obtained in which in-plane field (H=3 kOe) was applied in the directions along the hard and the easy axes with respect to the lattice plane. The temperature dependences of magnetic anisotropy and exchange bias were also studied along the magnetic easy and hard axes. As temperature decreases, the single peak splits into two peaks. While no exchange bias was observed along the magnetic easy axis, the exchange bias field steadily increased with decreasing temperature along the magnetic hard axis. These results were interpreted in connection with the magnetic anisotropy and the effect of the anti-dots in pinning domain wall motion along the respective direction.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.134-142
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• 2003

Most of the vibration and noise generating in small boats come from shipboard machinery such as main engine, generator and auxiliary machinery etc. In order to build up the comfortable environment for the crew and to reduce the ambient noise, and provide basic materials for reasoning selection application, the design under allowable vibration & noise conditions and the examination of vibration condition of the new ships, this paper researches the frequency spectrum and order analysis of vibration and noise. The obtained results are summarized as follows : Through comparing the small boat internal noise with the regulation of IMO and DNV, it revealed that the noise level of main engine room accords with the standard, and the noise of other places are beyond the values. In this paper, two boats are analyzed, which are same type, same size and power, but the main engines noise of them is different. In order to search the noise source, the noise of main engine room and relative parts are measured. The third order of measured points is dominant in frequency domain by the order analysis.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.610-622
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• 2003

Metadata Registry was developed to dynamically manage metadata and to increase interoperability between various and heterogeneous metadata. The built metadata registry can be used as a standard guideline for creation of new databases and it provides a radical data integration mechanism. However, in the situation that an enormous databases must be integrated progressively, there is a limit to the existing metadata-based approach. In case that each database has no statistical information for its use rate and the restricted cost is given to us for a unit time, existing metadata-based approaches do not provide how to select some databases to be preferentially integrated and to build a metadata registry progressively, In this paper, we propose a methodology that can create progressively metadata registries in the case. The proposed methodology is based on data visibility and hierarchical metadata registry. We also describe the system that have been developed for applying the methodology to a real domain, and then described its results.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.527-539
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• 2010

Most video coding systems use YCbCr color space for their inputs, but RGB space is more preferred in the field of high fidelity video because the compression gain from YCbCr becomes disappeared in the high quality operation region. In order to improve the coding performance of RGB video signal, this paper presents an adaptive frequency-selective weighted prediction algorithm. Based on the sign agreement and the strength of frequency-domain correlation of residual color planes, the proposed scheme adaptively selects the frequency elements as well as the corresponding prediction weights for better utilization of inter-plane correlation of RGB signal. Experimental results showed that the proposed algorithm improves the coding gain of around 13% bitrate reduction, on average, compared to the common mode of 4:4:4 video coding in the state-of-the-art video compression standard, H.264/AVC.

• Journal of Internet Computing and Services
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• v.8 no.6
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• pp.135-144
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• 2007

Feature models are widely used in domain engineering phase of software product lines development to model the common and variable concepts among products. From the feature model, the feature configurations are generated by selecting the features to be included in target product. The feature configuration represents the requirements for the specific product to be implemented. Although there are a lot of researches on how to build and use the feature models and feature configurations, the researches on the formal semantics and reasoning of them are rather inactive. This paper proposes the feature configuration verification approach based on JESS, java-based rule-base system. The Graph Product Line, a standard problem for evaluating the software product line technologies, is used throughout the paper to illustrate this approach. The approach in this paper has advantage of presenting the exact reason causing inconsistency in the feature configuration. In addition, this approach should be easily applied into other software product lines development environments because JESS system can be easily integrated with Java language.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.407-415
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• 2011

The stability condition and wideband characteristics of 3D ID-FDTD algorithm which has low dispersion error with isotropic dispersion are presented in this paper. 3D ID-FDTD method was proposed to improve the defect of the Yee FDTD such as the anisotropy and large dispersion error. The published paper calculated the stability condition of 3D ID-FDTD algorithm by using numerical method, however, it is thought that the examples were not sufficient to verify the stability condition. Thus, in this paper, various simulations are included in order to hold reliability under the conditions that the plane wave propagation is assumed with a single frequency and a wideband frequency. Also, the 3D ID-FDTD algorithm is compared to those that have the similar FDTD algorithm with ID-FDTD such as Forgy's method and non-standard FDTD method in a wideband. Finally, the radar cross section(RCS) for the large sphere with high dielectric constant is calculated.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.1-10
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• 2013

The recent trend in the war fields on the globe may be characterized by the network-centric warfare, which would, in turn, make the concept of weapon systems be changed. To this end, the concept of system of systems (SoS) has been introduced in literature. An SoS is a collection of multiple systems, each of which is an independent system and can be interoperable with each other. Thus, in defense domain each SoS is a big weapon system as a whole operated in actual environment and each element of it is also an independent smaller weapon system, but they should be interoperable via network among each other. The safety results studied for each elementary system alone may not be fully applicable to the whole SoS. As such, the objective of this paper is to study how to make the SoS safety requirements be distributed down over the interoperable elementary systems. Since handling the interoperability requires a technique of systems architecture, a standard method called the DoD Architectural Framework (DoDAF) has been used here to derive a solution. Using DoDAF, the safety requirements were first analyzed in the operability environment. The results were then studied to be included in an integrated model of both the systems design and safety processes. A further study of present paper would facilitate ensuring safety in the development of SoS weapon systems in practice.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.266-274
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• 2005

We have designed photonic crystal based bandpass filters whose characteristics are suitable for WDM communication system. The filters consist of coupled point defect resonators in two-dimensional photonic crystal. The frequency response of coupled resonators has been analyzed by the coupling of modes in time, from which the design parameters for the coupled resonator filters have been extracted. For the appropriate choice of the design parameters, each resonator is treated as a lumped L-C resonance circuit, and from the analogy between the equivalent circuit and the standard L-C filter circuits, the design parameters are simply determined from the table for general filter circuit design. Based on the determined design parameters, a photonic crystal based filter has been designed and its performance has been calculated using the finite-difference time-domain method. The designed filter shows a pass band of 50GHz and 0.5 dB in-band ripple, which is suitable for typical WDM communication systems with 100GHz channel spacing.