• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.874-877
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• 1987

In this paper a DPLL circuit realizable by digital IC's is propose and the principles of general DPLL are described. An all Digital phase locked loop is designed, analyzed, and tested. In particular, the approach of invoking Gaussian assumption on the decision variable and based on S.O.Rices theory is used. As a performance of the above PLL detector operating on low data rate FSK is given and demonsrtated to be FSK reception.

• Journal of the Korean Home Economics Association
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• v.42 no.5
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• pp.11-25
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• 2004

This study analyzed information sharing and digital divide within family and their consequences on the power structure between parents and their children based on the resource-exchange theory. In-depth interview has been conducted to collect data and materials for analysis. Major findings are: first, children recognized the ability to use information technology as resources, while parents did not; second, digital divide between parents and children seemed to be associated with laissez-faire communication between parents and children and worked as a cause of conflict between parents and children; third, reverse-socialization from children to parents occurred in consumer socialization in the family. Based on the findings, the implications to further research were provided.

• International Journal of Contents
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• v.8 no.4
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• pp.78-87
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• 2012

In this paper, we conducted cross-cultural studies on digital images, which is an important element of the user interface. We brought in the schema theory to explain the cross-cultural difference in expressing and perceiving digital images. Participant-ethnography, in-depth interview, and card sorting were conducted to explore how expression and perception of images are influenced by schemas. Our results of qualitative studies indicate that there are differences in schemas between cultures depending on the topic of expression and perception. With these results, we suggest globalization and localization strategies for websites.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1083-1086
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• 2005

Now these days, many technical concepts and tools have been developed in the cryptographic field. Most digital signature schemes used in practice, such as RSA or DSA, have an important role in information privacy and secure authentication for perfect user. A clearly advantage of such schemes over with security proven relative to such common cryptographic assumptions, is their efficiency: as a result of their relative weak requirements regarding computation, bandwidth and storage, these scheme have so far beaten proven secure schemes in practice. Our aim is to contribute to bridge the gap that exists between the theory and practice of digital signature schemes. In this paper we present a digital signature that ensures information privacy. More precisely, under an appropriate assumption about RSA, the scheme is proven to be existentially forgeable under adaptively chosen message attacks. This mechanism can be applied to smart cards or E-Wallet for maintaining secure authentication for user’s information privacy.

• Journal of Korean Institute of Industrial Engineers
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• v.13 no.2
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• pp.17-34
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• 1987

Modern telecommunication switching systems are SPC (Stored Program Control) machines handling voice, data and other kinds of traffic, in an environment which tends to be fully digital switching and transmission. The throughput of such systems is determined by the real time capacity of its centralized or distributed control processors and by the traffic capacity of the switching network. Designers must verify the traffic and call processing capacity of the switching system and check its performance under traffic load before it is put into service. Verification of traffic and call processing capacity of switching systems is one of the problems treated by teletraffic studies; teletraffic studies are based on stochastic process, queueing theory, simulations and other quantitative methods of decision making. This paper reviews the general methodologies to evaluate the throughput and performance of the digital switching system. TDX-10, which is a fully digital switching system under development in ETRI, is employed to give illustrative examples of the methodologies discussed in this paper.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.420-425
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• 2004

Lee and Kang measured side-necking deformation near a crack-tip for CT specimen using Stereoscopic Digital Speckle Photography and Digital Image Correlation. In this work the same technique was applied to SENB specimen. We happened to find that the deformation shape of the side-necking is similar to the one of plastic region estimated by McClictock using slip line theory. Based on volume constancy of plastic deformation as well as this finding, it is expected that a linear relationship holds between the volume of plastic deformation region and the one of side-necking upon the lateral surface of a specimen. To prove the idea, a preliminary study has been performed using 3-D finite element method on a model with modified boundary layer formulation. As the result, it is shown that the idea works well with acceptable error.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.231-239
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• 2003

A Digital Wave Tank simulation technique based on a finite-difference method and a modified marker-and-cell (MAC) algorithm is applied to investigate the characteristics of nonlinear Tsunami propagations and their interactions with a 2D sloping beach and Ohkushiri island, and to predict maximum wave run-up around the island. The Navier-Stokes (NS) and continuity equation are governed in the computational domain and the boundary values updated at each time step by a finite-difference time-marching scheme in the frame of rectangular coordinate system. The fully nonlinear kinematic free-surface condition is satisfied by the modified marker-density function technique. The Nearshore Tsunami is assumed to be a solitary wave and generated from the numerical wavemaker in the developed Digital Wave Tank. The simulation results are compared with the experiments and other numerical methods based on the shallow-water wave theory.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.447-449
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• 1993

Digital filter is a signal processor which converts the sequence input sampled from analog signal into another sequence output. It includes software routines which filter digital signal, a computer system for executing the routines, and a data acquisition system which implements A/D, D/A signal conversion. In this paper, a data acquisition system is designed and implemented for one-board computer of MC68000. Also, the theory regarding signal conversion and and its problems occured in implementation are considered. And then, with the hardware implemented like this, design of a digital low-pass filter with the cutoff frequency of 200Hz is implemented, and related characteristics are considered.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.1-5
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• 2002

A common way to design a digital control system is to design an analog controller first and discretize it for digital implemention. In this paper, optimal digital controller design is studied within the framework of sampled -data control theory. In particular, multirate discretization of analog controller is considered using an Η$_2$optimality criterion. Solutions are obtained via multirate H2 optimization with a causality constraint due to the multirate structure. In design example, the comparison of the proposed methods is made with the conventional discretization methods, and demonstrate the superiority of the multirate design method.

• Journal of Information Processing Systems
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• v.13 no.6
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• pp.1585-1601
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• 2017

With the rapid development of computer technologies, a number of image modification methods have emerged, which have great impacts on the security of image information. Therefore, it is necessary to protect the integrity and authenticity of digital images, and digital watermarking technique consequently becomes a research hotspot. An effort is made to survey and analyze advancements of image watermarking algorithms based on singular value decomposition (SVD) in recent years. In the first part, an overview of watermarking techniques is presented and then mathematical theory of SVD is given. Besides, SVD watermarking model, features, and evaluation indexes are demonstrated. Various SVD-based watermarking algorithms, as well as hybrid watermarking algorithms based on SVD and other transforms for copyright protection, tamper detection, location, and recovery are reviewed in the last part.