• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.74-85
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• 2009

We propose an Agent-based Fault Tolerant Object Group model based on the agent technology and FTOG model with replication mechanism for effective object management and fault recovery. We define the five kind of agents - internal processing agent, registration agent, state handling agent, user interface agent, and service agent - that extend the functions of the FTOG model. The roles of the agents in the proposed model are to reduce the remote interactions between distributed objects and provide more effective service execution. To verify the effectiveness of the proposed model, we implemented the Intelligent Home Network Simulator (IHNS) which virtually provides general home networking services. Through the simulations, it is validated that the proposed model decreases the interactions of the object components and supports the effective fault recovery, while providing more stable and reliable services.

• Journal of Digital Contents Society
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• v.10 no.3
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• pp.413-421
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• 2009

Recently, various kinds of arcade games are offered through the network with the internet's development. And for the Grid Logic game, it is opened up for everyone who uses the internet but it has a disadvantage that only the provided puzzles can be played. To improve this, in this paper, we developed a Grid Logic game contents using an image of user's as a puzzle. In order to do this, we suggested a threshold decision method, the pre-processing stage of image processing. We showed a method of detecting aim image from a binary image, showed up by the suggested way, and a method of changing into the game data and carrier of the meaning as a specific image at the end of the game are the objects of this paper. The suggested algorithm is constructed as a Java applet and applied to the 10 objects such as characters, logos, persons, etc. to show that this algorithm is suitable for the appropriate acquisition of the Grid Logic game data through the experiment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.137-144
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• 2017

The business process of global third party logistics company is defined as a network of logistics activities which involves the products that are manufactured in the developing countries, such as Vietnam, China and so on, and delivered to North or South American countries via intermediate stopover sites. The third party logistics company usually uses proprietary logistics information system to support the related logistics activities. However, each consignor sometimes may require different business process based on the customer type or characteristics of their products. Therefore, the third party logistics company need to modify their business process to reflect customer's requirements, resulting in the modification of logistic information systems and additional costs. Therefore, a flexible mechanism is required to efficiently support the various types of requirements by the owners of the products. In this paper, first, we figured out various business rules related to third party global logistics activities. Second, we grouped the identified business rules into business processes, objects, relations, dependency, policy, representations, execution, and resources and further into precondition, postcondition, and invariant based on checking point in time. Furthermore, the categorized rules are classified into inter-activity and intra-activity rules based on the execution range. Third, we proposed a rule syntax to describe the defined rules into scripts which are understood by user and information system together. When each activity is executed, the rule manager checks whether there are rules related with the activity execution. Finally, we developed a prototype rule management system to show the feasibility of our proposed methodology and to validate it with an example.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.395-403
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• 2016

This study investigates SNS usage behaviors of SNS users with a change of SNS use environment and an increase of users. This study compares the difference of use motivation, preferred type, and main use SNS according to socio-demographic variable of SNS users using cross tabulation analysis and also conducts a comparative analysis of main use SNS of each SNS user using correspondence analysis. The results show main use motivation of SNS is relationship seek, most preferred type is closed type, and main use SNS is Kakaostory. Next, we find that there are differences on use motivation, preferred type, and main use SNS, depending on the socio-demographic characteristics of SNS users. The result of correspondence analysis shows how users are using SNS services and what structure their competitive relations of SNS services are made. In the conclusion, the study presents summary of the findings, implications, and tasks for further studies.

• Journal of the Korea Society of Computer and Information
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• v.8 no.1
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• pp.60-68
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• 2003

Now the development of using a internet and security equipment is Processed actively. But It is presented problems about compatability and availability between variable equipment as several protocol. It is able to occur the Problem which is not considered efficiency as monopoly security equipment for the standardization of some vendor As a using of VPN gateway equipment. the same equipments have been actually used only for sale a communication equipment which are not confirmed(authenticate) between of mutual equipments. These problem is remain which are not considered suitable network environment and Position by mutual authentication Processing. Because it is considered for only sale a equipment of several vendor. And You will be remain where is unable to protect from attack of using the same equipment, and You will need a actually Protected method. By authentication system of base on Pn , although there is an intended attack from the third intruder, users can be protected with safe from the physical attacks since he is not a Permitted user by employing CA-VPN gateway that is more viable than the previous VPN connection in its security and certification.

• Journal of Digital Contents Society
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• v.19 no.7
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• pp.1333-1339
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• 2018

Recently, as disasters caused by weather such as heavy rains have increased, interests in forecasting weather and disasters using radars have been increasing, and related studies have also been actively performed. As the Ministry of Environment(ME) has established and operated a radar network on a national scale, utilization of radars has been emphasized. However, persons in charge and researchers, who want to use the data from radars need to understand characteristics of the radar data and are also experiencing a lot of trials and errors when converting and calibrating the radar data from Universal Format(UF) files. Hence, this study developed a Radar Display and Analysis Program(RaDAP) based on Graphic User Interface(GUI) using the Java Programming Language in order for UF-type radar data to be generated in an ASCII-formatted image file and text file. The developed program can derive desired radar rainfall data and minimize the time required to perform its analysis. Therefore, it is expected that this program will contribute to enhancing the utilization of radar data in various fields.

• Journal of the Korea Society of Computer and Information
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• v.17 no.9
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• pp.91-101
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• 2012

Key exchange protocols are essential for building a secure communication channel over an insecure open network. In particular, password-based key exchange protocols are designed to work when user authentication is done via the use of passwords. But, passwords are easy for human beings to remember, but are low entropy and thus are subject to dictionary attacks. Recently, Zhao and Gu proposed a new server-aided protocol for password-based key exchange. Zhao and Gu's protocol was claimed to be provably secure in a formal adversarial model which captures the notion of leakage of ephemeral secret keys. In this paper, we mount a replay attack on Zhao and Gu's protocol and thereby show that unlike the claim of provable security, the protocol is not secure against leakage of ephemeral secret keys. Our result implies that Zhao and Gu's proof of security for the protocol is invalid.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.583-591
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• 2008

This paper proposes a resource allocation algorithm for minimizing the overall distortion of multiple users in orthogonal frequency division multiplex (OFDM). The proposed algorithm exploits the diversity of multiuser and the rate-distortion function using packet distortion model in a system with limited resources. We first induce a rate-distortion function considering error concealment and error propagation properties of H.264 video structures. Then we perform adaptive resource allocation utilizing multiuser diversity for minimizing the overall video quality degradation. We also consider the proportional rate which is pre-determined for each user. Simulation results show that compared to the previous time division multiple access method and the resource allocation method maximizing data rate, the proposed rate allocation algorithm substantially improves the received video quality.

• The Journal of the Korea Contents Association
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• v.8 no.9
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• pp.42-54
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• 2008

In recent years, embedded systems have been expanding their application domains from traditional embedded systems such as military weapons, robots, satellites and digital convergence systems such as celluar phones, PMP(Portable Multimedia Player), PDAs(Personal Digital Assistants) to Next Generation Personal Computers(NGPCs) such as eating PCs, wearable computers. The NGPCs are network-based, human-centric digital information devices diverged from the traditional PCs used mainly for document writing, internet searching and database management. Wearable computers with battery capacity and memory size limitations have to use real-time operating systems with small footprints and low power management techniques to provide user's QoS in spite of hardware constraints. In this paper, we have designed and implemented a low-power RTOS (called eRTOS) for wearable computers. The implemented eRTOS has 18KB footprints and the dynamic power management and the device power management schemes are adapted in it. Experimental results with wearable computer applications show that the low power techniques could save energy up to 47 %.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.1
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• pp.21-30
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• 2006

As the amount of information to be processed by computers has recently been increased, there has been cluster computing systems developed by connecting PCs and workstations using high-speed networks. hs a result, the studies on a cluster-based DBMS have been done with a wide range and it is necessary to develop a cluster manager for monitoring and managing cluster-based DBMSs. But, a cluster manager for efficiently managing cluster-based DBMSs has been studied in a first step. In this paper, we design and implement a high-availability cluster manager for a cluster-based DBMS. It monitors the status of nodes in cluster systems as well as the status of DBMS instances in a node, by using a graphic user interface (GUI). Our cluster manager supports the high-availability for a cluster-based DBMS by perceiving errors and recovering them, based on the monitored information on the status of a server.