• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.20-26
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• 2012

The newly introduced model of a STTC-based Distributed Wireless Communication System (DWCS) can provide the capability of joint control of the signals at multiple cells. This paper has considered the virtual cell systems: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. The considered system constructs DVC by using antenna selection method. Also, for multi-user high-rate data transmission, the proposed system introduces multiple antenna technology to get a spatial and temporal diversity gain and exploits space-time trellis codes known as STTC to increase a spectral efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1002-1015
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• 2018

The advent of Internet of Things (IoT) and the evident inadequacy of Cloud networks concerning management of numerous end nodes have brought about a shift of paradigm giving birth to Fog computing. Fog computing is an extension of Cloud computing that extends Cloud resources at the edge of the network, closer to the user. Cloud computing has become one of the essential needs of people over the Internet but with the emerging concept of IoT, traditional Clouds seem inadequate. IoT entails extremely low latency and for that, the Cloud servers that are distant and unknown to the user appear to be unsuitable. With the help of Fog computing, the Fog devices installed would be closer to the user that will provide an immediate storage for the frequently needed data. This paper discusses data migration between different storage types especially between Cloud devices and then presents a mechanism to migrate data between Cloud and Fog Layer. We call this mechanism Adaptive Deadline-Aware Scheme (ADAS) for Data migration between Cloud and Fog. We will demonstrate that we can access and process latency sensitive "hot" data through the proposed ADAS more efficiently than with a traditional Cloud setup.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.493-500
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• 2010

XML Web Service is a new distributed computing paradigm for combining all computer systems through the on-line standardized open network, so it is expected that companies can get the results of increasing profits and reducing costs through this. Especially XML Web Service is essential in mobile environment. In this paper, a new XML Web Service is proposed and it is based on WIPI-based XML standard technology and mobile web service standard. The proposed XML Web Service embodied XML Parser which can be used in WIPI environment and made HTTP communication. In addition, as an example of the practical application, it was applied to an inventory Management, Book Store using JAVA language for WIPI.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2732-2753
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• 2019

With the application of wireless sensor networks in the fields of ecological observation, defense military, architecture and urban management etc., the security problem is becoming more and more serious. Characteristics and constraint conditions of wireless sensor networks such as computing power, storage space and battery have brought huge challenges to protection research. Inspired by the danger theory in biological immune system, this paper proposes an intrusion detection model for wireless sensor networks. The model abstracts expressions of antigens and antibodies in wireless sensor networks, defines meanings and functions of danger signals and danger areas, and expounds the process of intrusion detection based on the danger theory. The model realizes the distributed deployment, and there is no need to arrange an instance at each sensor node. In addition, sensor nodes trigger danger signals according to their own environmental information, and do not need to communicate with other nodes, which saves resources. When danger is perceived, the model acquires the global knowledge through node cooperation, and can perform more accurate real-time intrusion detection. In this paper, the performance of the model is analyzed including complexity and efficiency, and experimental results show that the model has good detection performance and reduces energy consumption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.2
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• pp.587-608
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• 2022

The European Union recently established the General Data Protection Regulation (GDPR) for secure data use and personal information protection. Inspired by this, South Korea revised their Personal Information Protection Act, the Act on Promotion of Information and Communications Network Utilization and Information Protection, and the Credit Information Use and Protection Act, collectively known as the "Three Data Bills," which prescribe safe personal information use based on pseudonymous data processing. Based on these bills, the personal data store (PDS) has received attention because it utilizes the MyData service, which actively manages and controls personal information based on the approval of individuals, and it practically ensures their rights to informational self-determination. Various types of PDS models have been developed by several countries (e.g., the US, Europe, and Japan) and global platform firms. The South Korean government has now initiated MyData service projects for personal information use in the financial field, focusing on personal credit information management. There is also a need to verify the efficacy of this service in diverse fields (e.g., medical). However, despite the increased attention, existing MyData models and frameworks do not satisfy security requirements of ensured traceability, transparency, and distributed authentication for personal information use. This study analyzes primary PDS models and compares them to an internationally standardized framework for personal information security with guidelines on MyData so that a proper PDS model can be proposed for South Korea.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2285-2301
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• 2012

Peer-to-Peer (P2P) networks are becoming more and more popular in video content delivery services, such as Video on Demand (VoD). Scalability feature of P2P allows a higher number of simultaneous users at a given server load and bandwidth to use stream service. However, the quality of service (QoS) in these networks is difficult to be guaranteed because of the free-riding problem that nodes download the recourses while never uploading recourses, which degrades the performance of P2P VoD networks. In this paper, a distributed trust model is designed to reduce node's free-riding phenomenon in P2P VoD networks. In this model, the P2P network is abstracted to be a super node hierarchical structure to monitor the reputation of nodes. In order to calculate the reputation of nodes, the Hidden Markov Model (HMM) is introduced in this paper. Besides, a distinction algorithm is proposed to distinguish the free-riders and malicious nodes. The free-riders are the nodes which have a low frequency to free-ride. And the malicious nodes have a high frequency to free-ride. The distinction algorithm takes different measures to response to the request of these two kinds of free-riders. The simulation results demonstrate that this proposed trust model can improve QoS effectively in P2P VoD networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.549-561
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• 2005

As Internet and network technologies have been developed, e-commerces are getting more complex and more various. This paper, for meta-data and data exchange between heterogeneous database systems, uses XML schema proposed in W3C, and XML schema can present meta-data and data of relational database system as XML document format which is structural. It supports various primitive data formats, so that it uses the structure which reflects adequately data formats which relational database system offered. However, current e-commerces use heterogeneous platforms, so difficulties that is mutual interchange and management exist. For the solution for these problems, a standard ontology which defines relations of product classifications and the standard of property expression and the location ontology which offers e-commerce's information about products are constructed. Applying these ontology information to search system, by offering information which customers need efficient search is performed. Combining these ontologies and product classification category information, called XMDR, this XMDR is introduced into product search system, so this paper proposes to construct ontology server method for efficient search.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.175-181
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• 2006

AMobile-supported spatial database systems have been introduced with development of mobile computing technology, they offer an advantage that we can access the data wherever we are. However, the studies on database system in traditional distributed environments must be reconsidered again, because of characteristics of mobile database system such as mobility and instability of wireless network. A new transaction model should be required for considering the characteristics, since especially a mobile computing environment is location-dependent, compared with the location transparency in a distributed computing environment. In other aspect, normally mobile host may be moving not in all space, but in some limited path. That is, a host is moving along the roads or the geographical features adjacent to the roads. The transaction processing should be considered not on the spatial coordinate but on the geographical features. In this paper, the feature based transaction processing model is proposed to process location-dependent transaction efficiently.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.12
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• pp.642-652
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• 2001

Recently, the advent of World-Wide-Web(WWW) and the explosive popularity of the Internet gave birth to collaborative applications which were enabled by computers and networks as their primary media. The progress of 3D computer graphics enabled collaborative application with 3D virtual environments or distributed virtual environments. In this paper, we explain our implementation of the Share collaboration engine which is for collaboration applications based on a distributed virtual environment. We introduce Virtual Architectural Engineering 2000 (VAE2000) that is our pilot application implemented with the Share collaboration engine. The Share collaboration engine proposes a new Share network architecture for management of participants, and it provides some synchronization methods for 3D objects in virtual collaboration. VAE2000 is an experimental application that tries to prevent wastes of human, material and time resources in networked virtual collaboration.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.525-531
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• 2020

In today's IT environment where various pieces of information are distributed in large volumes, recommendation systems are in the spotlight capable of figuring out users' needs fast and helping them with their decisions. The current recommendation systems, however, have a couple of problems including that user preference may not be reflected on the systems right away according to their changing tastes or interests and that items with no relations to users' preference may be recommended, being induced by advertising. In an effort to solve these problems, this study set out to propose a Fuzzy-AHP-based movie recommendation system by applying the BRNN(Bidirectional Recurrent Neural Network) language model. Applied to this system was Fuzzy-AHP to reflect users' tastes or interests in clear and objective ways. In addition, the BRNN language model was adopted to analyze movie-related data collected in real time and predict movies preferred by users. The system was assessed for its performance with grid searches to examine the fitness of the learning model for the entire size of word sets. The results show that the learning model of the system recorded a mean cross-validation index of 97.9% according to the entire size of word sets, thus proving its fitness. The model recorded a RMSE of 0.66 and 0.805 against the movie ratings on Naver and LSTM model language model, respectively, demonstrating the system's superior performance in predicting movie ratings.