• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.411-413
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• 2010

Now, smart phone markets are grows quickly. So it is needed research of CDN(Contents Delivery Network) technology for contents transmission in mobile networks. Especially the services of smart phone are focused on open platform model. So P2P(Peer to Peer) protocols will be used for mobile network because it is a distributed network architecture composed of participants that make a portion of their resources directly available to other network participants, without the need for a central server. Current research of P2P protocols for mobile network are not activated. The reason is appropriate in the mobile P2P network simulation environment, since it is not provided. So, in this paper we design a mobile P2P simulation system for CDN based on mobile P2P.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.5
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• pp.712-717
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• 2007

Using home network system including home server, home service robot, a variety of device, it is generally known that application of Multi Agent System for performing variously distributed process that can be occur in home environment, is efficient method. In this system, it is intelligent service robot that a key of human interface and physical service offer Therefore, using application of established multi agent system, we can defined Multi Agent Robot System. In 'open' home environment, between all agent data interaction and cooperation are needed for Multi Agent System offer to user that more efficient service. For this, we focus our attention on define as agent that can autonomic drive and offer to user that physical service robots and, design, suggest the simulator can display that between robot agents communication or between other agents, like home server, and robot agents communication information to user interface.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.4
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• pp.113-124
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• 2009

A research of grid computing that is the combination of computer resources from multiple distributed administrative domains to get large amount of computing power is underway. This research is an application of grid technology on a urban facilities management system based on u-GIS. The sensors are set up in the urban facilities to make it monitoring. If an amount of sensors and gateways is increased, the server needs more computing resources to process the data. In this study we developed the skills that can distribute jobs to idle gateway, in case of the server capacity had approached threshold. It will be possible to develop of economic and efficient system that will apply to large amount of data processing about u-City.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.1
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• pp.103-110
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• 2019

Electronic voting has been followed by a lot of research as it provides convenience to voters and increases participation rates. Nevertheless, electronic voting has not been widespread yet. The existing electronic voting system does not guarantee credibility, and there arises a question on the security that the voting could be forged or altered by the attack to the central server. In this paper, we proposed blockchain based systems to solve the problems in electronic voting. Although the blockchain may guarantee the security of transaction data, there have been only a few electronic voting systems implemented using the blockchain. We developed blockchain enabled voting and brought out some of its related legal, technical and operational challenges to enforce more security in voting. Unlike centralized voting, the systems could enforce security and solve the problems such as forgery or alteration of transaction data caused by hacking or any attempts to gain control of the central server system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1511-1517
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• 2018

Mobile Device-to-Device (D2D) caching networks can transmit multimedia data to users directly without passing through any network infrastructure by storing popular multimedia contents in advance that are popular among many mobile users at caching server devices (CSDs) in distributed manners. Thus, mobile D2D caching networks can significantly reduce backhaul traffic in wired networks and service latency time of mobile users. In this paper, we propose an efficient transmission scheme that can enhance the transmission efficiency of mobile D2D caching networks by using multiple CSDs that are caching the contents that are popular among mobile users. By sorting the multiple CSDs that are caching a content that mobile users want to receive according to their channel gains, the proposed scheme can reduce the complexity of algorithm significantly, compared to an optimal scheme based on Brute-force searching, and can also obtain much higher network transmission efficiency than the existing Blanket and Opportunistic transmission schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.79-89
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• 2004

Mobile IP Low Latency Handoffs allow greater support for real-time services on a Mobile W network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authenticate the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to old foreign agent. In order to reduce these extra time overheads, we present a method that performs Low Latency Handoffs without requiring funker involvement by home AAA server. The method re-uses the previously assigned session keys. To provide confidentiality and integrity of session keys in the phase of key exchange between agents, it uses a key sharing method by gateway foreign agent that Performs a ousted thirty party. The Proposed method allows the mobile node to perform Low Latency Handoffs with fast as well as secure operation

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.50-55
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• 2021

Multi-path system is a system in which utilizes various networks simultaneously. It is expected that multi-path system can enhance communication speed, reliability, security of network. In this paper, we focus on path selection in multi-path system. To select optimal path, we propose deep reinforcement learning algorithm which is rewarded by the round-trip-time (RTT) of each networks. Unlike multi-armed bandit model, deep Q learning is applied to consider rapidly changing situations. Due to the delay of RTT data, we also suggest compensation algorithm of the delayed reward. Moreover, we implement testbed learning server to evaluate the performance of proposed algorithm. The learning server contains distributed database and tensorflow module to efficiently operate deep learning algorithm. By means of simulation, we showed that the proposed algorithm has better performance than lowest RTT about 20%.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.13-18
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• 2022

In this paper, we proposed VW-FedAVG(Validation based Weighted FedAVG) which updates the global model by weighting according to performance verification from the models of each device participating in the training. The first method is designed to validate each local client model through validation dataset before updating the global model with a server side validation structure. The second is a client-side validation structure, which is designed in such a way that the validation data set is evenly distributed to each client and the global model is after validation. MNIST, CIFAR-10 is used, and the IID, Non-IID distribution for image classification obtained higher accuracy than previous studies.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.8
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• pp.259-268
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• 2022

With prosperous usage of cloud services to improve management efficiency due to the explosive increase in data volume, various cryptographic techniques are being applied in order to preserve data privacy. In spite of the vast computing resources of cloud systems, decrease in storage efficiency caused by redundancy of data outsourced from multiple users acts as a factor that significantly reduces service efficiency. Among several approaches on privacy-preserving data deduplication over encrypted data, in this paper, the research results for improving efficiency of encrypted data deduplication using trusted execution environment (TEE) published in the recent USENIX ATC are analysed in terms of security and efficiency of the participating entities. We present a way to improve the stability of a key-managing server by integrating it with individual clients, resulting in secure deduplication without independent key servers. The experimental results show that the communication efficiency of the proposed approach can be improved by about 30% with the effect of a distributed key server while providing robust security guarantees as the same level of the previous research.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.125-135
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• 2010

Mobile office is becoming common as advances in mobile devices such as PDAs, Smart-phones, or wireless Internet. In this paper, we construct a mobile office environment on a geotechnical information system(GIS). Especially, web services and XML technology combined with SOA (service oriented services) are adopted for various types of mobile devices and services in a minimum cost. Web service and XML can provide an excellent SW reusability, extensibility, and interoperability even for heterogeneous distributed systems. Applications can exploit web services by just knowing server's address. Prototype system integrates a client in Visual Basic.Net and server in Java via the web services and XML data exchange. We verify effectiveness of the approach through the implementation of prototype system.