• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.424-429
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• 2014

This paper investigates the problem of synchronization of the Pehlivan chaotic system based on sliding mode control and GA. For this, a brief overview of the Pehlivan chaotic system is given. Then, the conventional sliding mode control technique is described and a synchronization method using GA strategy is proposed. The proposed method is that the GA searched the parameters including sliding plane and control gains) selected by the designer in the sliding mode control are searched optimally through the GA. The GA in the MATLAB Toolbox was used and simulation work is shown to illustrate the effectiveness of the synchronization schemes for the chaotic system.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.10
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• pp.373-380
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• 2022

This paper presents a deep learning based group synchronization that supports networked immersive interactions between remote users. The goal of group synchronization is to enable all participants to synchronously interact with others for increasing user presence Most previous methods focus on NTP-based clock synchronization to enhance time accuracy. Moving average filters are used to control media playout time on the synchronization server. As an example, the exponentially weighted moving average(EWMA) would be able to track and estimate accurate playout time if the changes in input data are not significant. However it needs more time to be stable for any given change over time due to codec and system loads or fluctuations in network status. To tackle this problem, this work proposes the Deep Group Synchronization(DeepGroupSync), a group synchronization based on deep learning that models important features from the data. This model consists of two Gated Recurrent Unit(GRU) layers and one fully-connected layer, which predicts an optimal playout time by utilizing the sequential playout delays. The experiments are conducted with an existing method that uses the EWMA and the proposed method that uses the DeepGroupSync. The results show that the proposed method are more robust against unpredictable or rapid network condition changes than the existing method.

• Journal of Distribution Science
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• v.16 no.2
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• pp.19-24
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• 2018

Purpose - Drone delivery is expected to revolutionize the supply chain industry. This paper aims to introduce a collaborative parcel delivery problem by truck and drone (hereinafter called "TDRP") and propose a novel heuristic method to solve the problem. Research design, data, and methodology - To show the effectiveness of collaborative delivery by truck and drone, we generate a toy problem composed of 9 customers and the speed of drone is assumed to be two times faster than truck. We compared the delivery completion times by 'truck only' case and 'truck and drone' case by solving the optimization problem respectively. Results - We provide literature reviews for truck and drone routing problem for collaborative delivery and propose a novel and original heuristic method to solve the problem with numerical example. By numerical example, collaborative delivery is expected to reduce delivery completion time by 12~33% than 'truck only' case. Conclusions - In this paper, we introduce the TDRP in order for collaborative delivery to be effective and propose a novel and original heuristic method to solve the problem. The results of research will be help to develop effective heuristic solution and optimize the parcel delivery by using drone.

• Proceedings of the CALSEC Conference
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• 2003.09a
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• pp.249-254
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• 2003

Object caching is a desirable feature to improve the both scalability and performance of distributed application systems for information infrastructure, the information management system leveraging the power of network computing. However, in order to exploit such benefits, we claim that the following problems: cache server placement, cache replacement, and cache synchronization, should be considered when designing any object cache system. We are under developing DOC: a Distributed Object Caching, as a part of building our information infrastructures. In this paper, we show how each problem is inter-related, and focus to highlight how we handle cache server deployment problem

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.24-32
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• 2013

Authentication is one of the necessary elements in the network environment. Many researches have detected security vulnerabilities to the existing authentication mechanisms and suggested secure mutual authentication protocols by resolving these vulnerabilities. The representative ones of them are SPMA(Strong Pass Mutual Authentication) and I-SPMA(Improved Strong Password Mutual Authentication). However, these protocols cause a critical problem when the shared secret information is de-synchronized between the server and the client. This paper proposes a revised protocol to resolve the de-synchronization problem. Based on a security assessment on the proposed protocol, we consider the proposed protocol is safer than the previous ones and possible to effectively make a user authentication system mre secure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2891-2898
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• 2014

It is feasible to develop a fault tolerant system through module level redundancy on the Integrated Modular Avionics (IMA). However, its great implementation complexity is one of important challenges when asynchronous hardware environment is naturally assumed. To solve this problem, Physically Asynchronous Logically Synchronous (PALS) on IMA has been proposed. But, it has adaptation problem by not addressing specific architecture for IMA system. In the paper, we propose how to synchronize the input data on the IMA system under primary/secondary redundancy architecture by referring to existing PALS. In the proposed scheme, we introduce window frame by considering rate monotonic scheduling and analyze the adequate the synchronization time. Finally, we verify the feasibility of the proposed design pattern through the systematic experiments.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.470-477
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• 2015

This paper presents a new technique for generating an optimum synchronizable test sequence that can be applied in the distributed test architecture where both external synchronization and input/output operation costs are taken into consideration. The method defines a set of phases that constructs a tester-related digraph from a given finite state machine representation of a protocol specification such that a minimum cost tour of the digraph with intrinsically synchronizable transfer sequences can be used to generate an optimum synchronizable test sequence using synchronizable state identification sequences as the state recognition sequence for each state of the given finite state machine. This hybrid approach with a heuristic and optimization technique provides a simple and elegant solution to the synchronization problem that arises during the application of a predetermined test sequence in some protocol test architectures that utilize remote testers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1285-1291
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• 2009

Recently the Internet and multimedia technique quickly, develops and to follow multimedia information which is many at the network it is quick and widely, it will be able to exchange. And the synchronization problem for the time and a space of the multimedia object which is various exists. In order to solve like this problem point SMIL where it puts a base in XML it will be able to compose the multimedia object expression which is various from W3C standard was proposed. About under integrating to express a multimedia data the individual multimedia object of the synchronization language for and chain with time it will be able to integrate with the multimedia presentation which has become motive anger space in order. In this thesis provides that uses various multimedia object and users integrate multimedia object with synchronization easily SMIL Authoring system that can presentation design and implemented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.653-656
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• 2009

Currently with development of development and the hardware of the superhigh speed network about increase is spreading out at the rapid pace the many multimedia contents quite from internet. The production environment is growing about the multimedia contents because of such as circumstance, as well as multimedia contents will increase. However, Numerous voice, the picture, with text etc. the time of the same multimedia contents and problem of spatial synchronization occur, started. W3C(World Wide Web Consortium) solves like this problem point presented the method for. Does so, SMIL(Synchronized Multimedia Integration Language) where puts a base in XML(Extensible Markup Language) will be able to compose the expression of the multimedia contents which is various standard was proposed. SMIL the individual multimedia object of chain with time will be able to integrate with the multimedia presentation which is synchronized spatial in order. In this paper a variety of multimedia content and synchronization of the time and space, to be represented by integrating the design and implementation of SMIL authoring system.

• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3785-3793
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• 2000

Effective synchronization specification model which can specify temrxlral relationship among media resolving asynchronous problem due to variable network delay is necessary in a distributed multimedia system. Therefore in this paper, we propose RTPN(Real- Time Petri Net) synchronization specification model based on Petri Net for multimedia application in a distributed real time environment. The proposed RTPN model supplies a tlexible decsription of the temporal relationship among various media objects by defining primary key media and relative key media according to delay and importance among media. Firing rule is instantly executed by firing function based on QoS values which supports intra-media and inter-media syncbronization. And asynchronous control algorithm for resynchronization of presentation level is possible more effective supporting of QoS.