• Journal of the Institute of Convergence Signal Processing
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• v.13 no.3
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• pp.119-129
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• 2012

In the medical field, the hardening of tissues is one of important informations used in diagnosis or understanding progress of disease, a quantitative measuring method of hardening is important for objective diagnosis. It has been proposed MRE(Magnetic Resonance Elastography) method that measures an index of hardening, viscoelastic properties in a noninvasive. Because the S/N ratio of MRE images go down when measuring viscoelastic properties from local wavelength and local damping factor of a propagating wave in MRE method, methods using multiple phase MRE images have been examined to decrease the effect of noise. We propose a method measuring viscoelastic properties after Fitting a function for multiple phase MRE images in this research. This proposed method has a advantage to set up arbitrarily the variation rate of a space direction of viscoelastic properties or the spatial resolution of measuring values according to changing of the noise included in images, though it applies viscoelastic wave for multiple phase MRE images. We confirmed the effectiveness of a proposed method by experiment using simulation images and experiment using silicone-gel phantom.

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.71-78
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• 2013

This paper describes a multiple audio watermarking using Quantization Index Modulation (QIM) on frequency phase and magnitude response. Proposed embedding procedure is composed of two stage. At the first stage, the watermark is embedded on the frequency phase response using QIM. In the second stage, the watermark is embedded using adaptive QIM with the step-size that is adaptively determined using the maximum value of the frequency magnitude response of every frame. The watermark is extracted by calculating the Euclidean distance as the blind detection. The proposed method is robust against most of attacks of audio watermark benchmarking. For the Fourier attacks, the proposed method shows over 95% recovery rate.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.408-414
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• 2020

The method of overcoming the limitation of optical phase conjugator applied into optical long-haul link for transmitting high capacity wavelength division multiplexed (WDM) channels was investigated. The configuration of optical link was based on dispersion-managed link, in which dispersion compensating fiber inserted into each fiber span with single mode fiber, and optical phase conjugator was added into suitable location of link. The maximum number of fiber spans as a function of the launch power of WDM channels in optical link with optical phase conjugator placed at the proposed location was induced and compared for analyzing the compensation performance of the distorted WDM channels. It was confirmed that the more optical phase conjugator depart from the midway of total transmission length, the less the distorted WDM channels was compensated, however, it was also confirmed that the degradation of compensation can be overcome by the suitable value of residual dispersion per span and by the reasonable choice of fiber span controlling total dispersion accumulated in overall transmission link.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.1
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• pp.43-54
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• 2001

In this paper we study the use of polyinstantiation for spatial data, for the purpose of solving cover in topology channel in multilevel secure spatial database systems. Spatial database system with topological structure has a number of spatial analysis function using spatial data and neighbored one\`s each other. But. it has problems that information flow is occurred by topological relationship in spatial database systems. Geographic Information System(CIS) must be needed mandatory access control because there ,are many information flow through positioning information And topological relationship between spatial objects. Moreover, most GIS applications also graphe user interface(GUI). In addressing these problems, we design the MLS/SRDM(Multi Level Security/Spatial Relational Data Model) and propose polyinstantiation for spatial data for solving information flow that occurred by toplogical relationship of spatial data.

• Journal of KIISE:Software and Applications
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• v.28 no.12
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• pp.875-884
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• 2001

Although the self organizing map (SOM) is widely utilized in such fields of data visualization and topology preserving mapping, since it should have the topology fixed before trained, it has some shortcomings that it is difficult to apply it to practical problems, and classification capability is quite low despite better clustering performance. To overcome these points this paper proposes the dynamic topology preserving self-organizing map(DTSOM) that dynamically splits the output nodes on the map and trains them, and attempts to improve the classification capability by combining multiple DTSOMs K-Winner method has been applied to combine DTSOMs which produces K outputs with winner node selection method. This produces even better performance than the conventional combining methods such as majority voting weighting, BKS Bayesian, Borda, Condorect and reliability sum. DTSOM remedies the shortcoming of determining the topology in advance, and the classification rate increases significantly by combing multiple maps trained with different features. Experimental results with handwritten digit recognition indicate that the proposed method works out to problems of conventional SOM effectively so to improve the classification rate to 98.1%.

• Journal of IKEEE
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• v.10 no.1 s.18
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• pp.16-21
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• 2006

This paper shows a vernier delay technique for generating precise multiphase clocks using PLL structure. The proposed technique can achieve the finer timing resolution less than the gate delay of the delay chain in VCO. Using this technique, 62.5ps of timing resolution can be achieved if the reference clock rate is set at 1GHz using 0.18um CMOS technology. Jitter of 14ps peak-to-peak was measured.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.7
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• pp.394-400
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• 2002

Networks of Workstations(NOWs), that has features of flexibility and scalability, recently has emerged as an inexpensive alternative to massively parallel multicomputers. However it is not easier to perform deadlock-free multicast than regular topologies like mash or hypercube. Single phase differential multicast(SPDM) is a modified multicast algorithm with less burden of the root node. By applying quality of serviece(QoS), a specific node can have differentiated service and artificial change of message flow pattern is also available. As the results of performance evaluation experiments, SPDM has lower latency and lower packet concentration rate of the root node than the case of SPAM, and has ability to control network load distribution among switch nodes by controlling the assignment rate among nodes.

• Journal of IKEEE
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• v.22 no.3
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• pp.800-804
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• 2018

This paper presents a novel HF band differential quadrature phase-shift keying (DQPSK) orthogonal frequency-division multiplexing (OFDM) communication system. The system can deliver 3.6 kbps with a bandwidth of about 3 kHz. In a digital modem, OFDM with 32-point fast Fourier transform is used. In the system, each subcarrier uses DQPSK modulation. Hence, a demodulator does not require carrier phase recovery and symbol timing recovery. And, each subcarrier employs CRC error check code individually. By using CRC code for each subcarrier, bit error caused by multipath fading can be recovered simply.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1353-1361
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• 1992

Holographic optical element(HOE) is fabricated with the properties of lightweight, thin thickness and interconnectivity for free space. Particularly, HOE for optical interconnection and multiple image processing should have a high efficiency and equal spot intensity, Nonlinear equations for 2-dimensional binary phase grating(BPG) structure is solved by computer simulation based on modified Newton method. Computer-generated pattern drawn by plotter is scaled down and translated into the microfilm. After contact printing between the microfilm and silver halide hologram film, phase diffraction grating produces the $5{\times}5$ multiple spots. Experimental results are shown that bleached phase grating has a high efficiency and equal focused beams except central zero order.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6B
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• pp.563-574
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• 2004

In this paper, we propose a new class of MIN(Multistage Interconnection Network) called Combine MIN which combines static network topology and apimic network topology. Combine U provides multiple paths at a hardware cost lower than that of MIN with unique path property. Combine MIN can be constructed suitable for localized communication by providing the shortcut path and multiple paths inside the processor-memory cluster which has frequent data communications. According to the results of analysis and simulation for performance evaluation, Combine MIN shows higher performance than MINs of the same network size in the highly localized communication Therefore, Combine MIN can be used as an attractive interconnection network for parallel applications with a localized communication pattern in shared-memory multiprocessor systems.