Honam Research Center

Gwangju, South Korea

Honam Research Center

Gwangju, South Korea
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Yoo Y.,University of Texas at Austin | Yoo Y.,Honam Research Center | Vishwanath S.,University of Texas at Austin
Neural Computation | Year: 2015

Graphical models and related algorithmic tools such as belief propagation have proven to be useful tools in (approximately) solving combinatorial optimization problems across many application domains. A particularly combinatorially challenging problem is that of determining solutions to a set of simultaneous congruences. Specifically, a continuous source is encoded into multiple residues with respect to distinct moduli, and the goal is to recover the source efficiently from noisy measurements of these residues. This problem is of interest in multiple disciplines, including neural codes, decentralized compression in sensor networks, and distributed consensus in information and social networks. This letter reformulates the recovery problem as an optimization over binary latent variables. Then we present a belief propagation algorithm, a layered variant of affinity propagation, to solve the problem. The underlying encoding structure of multiple congruences naturally results in a layered graphicalmodel for the problem, overwhich the algorithms are deployed, resulting in a layered affinity propagation (LAP) solution. First, the convergence of LAP to an approximation of the maximum likelihood (ML) estimate is shown. Second, numerical simulations show that LAP converges within a few iterations and that the mean square error of LAP approaches that of the ML estimation at high signal-to-noise ratios. © 2015 Massachusetts Institute of Technology.

Jung Y.,Chonnam National University | Park J.,Chonnam National University | Choi S.-I.,Chonnam National University | Lee B.T.,Honam Research Center | And 3 more authors.
2011 Computation and Communication Technologies: 3rd International Conference on Advances in Computing, Control, and Telecommunication Technologies, ACT 2011 - Computer Science Series | Year: 2011

In order that multicast routing characteristics are reflected under wireless environments, multicast routing metric is required for qualifying the multicast tree cost in wireless multi-hop mesh networks. We design a new multicast routing metric called the multicast-tree transmission ratio which quantifies the multicast tree cost, considering the link quality of wireless multicast channels as well as the wireless multicast advantage. The multicast-tree transmission ratio represents the product of the multicast transmission ratios of all nodes in the constructed multicast tree. This paper proposes a wireless multicast routing which constructs the multicast tree by maximizing the multicast-tree transmission ratio in wireless mesh networks. The proposed wireless multicast routing shows a higher delivery ratio and a lower average delay than the multicast routing minimizing the transmission count. In comparison with other multicast routings, simulation results show that the proposed multicast heuristic maximizing the multicast tree transmission ratio constructs a cost-effective multicast tree in terms of its delivery ratio, average delay, and required network resources.

Lee H.H.,Applied Technology Internet | Lee J.H.,Applied Technology Internet | Lee S.S.,Applied Technology Internet | Rhy H.Y.,Ericsson AB | And 2 more authors.
COIN 2014 - 12th International Conference on Optical Internet | Year: 2014

We investigate ONU power leveling methods for mitigating Inter-channel crosstalk of upstream signals in TWDM-PON. 6-dB power dynamic range was archived with maximum 1.4-dB power penalty by adjusting operation current of Tx. The proposed method is thought to be a simple, low-cost solution in comparison with that with a VOA or SOA. Further study is needed for trade-off between crosstalk and eye distortion penalty and how to specify. © 2014 IEEE.

Lee M.,Honam Research Center | Min G.,Honam Research Center | Kim N.-W.,Honam Research Center | Lee B.T.,Honam Research Center | Song J.-H.,Jeonju University
ETRI Journal | Year: 2016

For the implementation of a real-time holographic camera, fast and automatic holographic image reconstruction is an essential technology. In this paper, we propose a new automatic depth-detection algorithm for fast holography reconstruction, which is particularly useful for optical scanning holography. The proposed algorithm is based on the inherent phase difference information in the heterodyne signals, and operates without any additional optical or electrical components. An optical scanning holography setup was created using a heterodyne frequency of 4 MHz with a 500-mm distance and 5-mm depth resolution. The reconstruction processing time was measured to be 0.76 s, showing a 62% time reduction compared to a recent study. © 2016 ETRI.

Kim N.-W.,Honam Research Center | Lee B.-T.,Honam Research Center | Kim Y.-S.,Honam Research Center
International Journal of Communication Systems | Year: 2013

In this paper, we propose a personally customizable content authoring service (C2Channel) using an Internet Protocol television (IPTV) platform, in which a user terminal such as a PC or set-top box sends various kinds of multimedia files from a camera or camcorder to a remotely located authoring server (C2Channel server). The C2Channel server creates personalized content in real time by combining special effects with the multimedia files transmitted from the user terminal and then retransmits them to a predefined relevant service group as a personal IPTV channel through an IPTV network provider. This content authoring service supplies an automatic multimedia editing/composition service and offers unicast, multicast, and groupcast services for a large number of interested groups via an IPTV-based real-time media delivery platform (Open Live IPTV Engine [OLIVE]), in which a service management server is used for user identification through the IPTV personal channel. Because this platform uses a remote server resource when authoring personally customizable content, resources remaining at the user's terminal can be variously utilized. Copyright © 2012 John Wiley & Sons, Ltd. In this paper, we propose a personally customizable content authoring service (C2Channel) using an Internet Protocol television platform, in which a user terminal such as a PC or set-top box sends various kinds of multimedia files from a camera or camcorder to a remotely located authoring server (C2Channel server) Copyright © 2012 John Wiley & Sons, Ltd.

Kim N.-W.,Honam Research Center | Son S.-C.,Honam Research Center | Lee B.-T.,Honam Research Center
Optical Engineering | Year: 2011

Recently, as effective demand for high-quality, large-capacity content such as three-dimensional (3D), multiangle, and gigabit-web has increased, a network infrastructure capable of satisfying future broadcast and communication service requirements is required. In this paper, we introduce a convergence service based on a gigabit network and then propose a technique for delivering gigabit 3D content. Here, the term 3D content delivery technique refers to an overlay-multicast-based distributed service platform that is comprised of a media relay agent and a management server. The service platform is designed to back up both live video and file-based video streaming. Using this platform, we can provide 3D remote education and 3D multiangle services via 3D-based video streaming between a service provider and service consumers dispersed at different locations. To evaluate our 3D content delivery technique, we run a series of trials of gigabit network-based 3D trial services to service subscribers. Then, we conduct a survey to measure user satisfaction with the 3D delivery service and simulated network and service quality. From experimental results, we confirm that this type of distributed service platform can be used as the delivery framework for applications such as realistic 3D-based seminars or 3D video conferences. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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