• Journal of KIISE
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• v.42 no.3
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• pp.399-407
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• 2015

Wireless sensor networks are used for data collection and processing from the surrounding environment for various applications. Since wireless sensor nodes operate on low computing power, restrictive battery capacity, and low network bandwidth, their architecture model has greatly affected the performance of applications. If applications have high computation complexity or require the real-time processing, the centralized architecture in wireless sensor networks have a delay in data processing. Otherwise, if applications only performed simple data collection for long period, the distributed architecture wasted battery energy in wireless sensors. In this paper, the energy consumption and processing delay were analyzed in centralized and distributed sensor networks. In addition, we proposed a new hybrid architecture for wireless sensor networks. According to the characteristic of applications, the proposed method had the optimal number of wireless sensors in wireless sensor networks.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.185-192
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• 1995

A common control model used to implement computer integrated manufacturing(CIM) is based on the hierarchical decomposition of the shop floor activities, in which supervisory controllers are responsible for all the interactions among subordinates. Although the hierarchical control philosophy provides for easy understanding of complex systems, an emerging manufacturing paradigm, agile manufacturing, requires a new control structure necessary to accommodate the rapid development of a shop floor controller. This is what is called CSCW(computer supported cooperative work)-based control or component-based heterarchical control. As computing resources and communication network on the shop floor become increasingly intelligent and powerful, the new control architecture is about to come true in a modern CIM system. In this paper, CSCW-based control is adopted and investigated, in which a controller for a unit of device performs 3 main functions - planning, scheduling and execution. In this paper, attention is paid to a planning function and all the detailed planning activities for CSCW-based shop floor control are identified. Interactions with other functions are also addressed. Generally speaking, planning determines tasks to be scheduled in the future. In other words, planning analyzes process plans and transforms process plans into detailed plans adequate for shop floor control. Planning is also responsible for updating the process plan and identifying/resolving replanning activities whether they come from scheduling or execution.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.6
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• pp.609-613
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• 2008

In Large scale system, components are developed by many different developers. In such a development environment, efficiency of the development depends largely on effectiveness of interface management. In the early stage of development, many components are newly defined or modified quite often. These definitions and modifications of components cause the change of interfaces between components. If changes of interfaces are not properly managed, many developers may implement components based on different version of interfaces. This causes decrease in efficiency of development. "Message Definition and Management system (MDMS)" provides the means to cope with the inefficiency of unmanaged interface definitions and changes. MDMS automatically generates source code and Interface Design Description (IDD). The automatic generation of source code and IDD prevents the disagreement between code and documents. Furthermore, MDMS shows the overall view of message flow for a system. Based on this information, we can optimize the system identifying message bottleneck and apply to support for the performance tuning of the system.

• KIISE Transactions on Computing Practices
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• v.23 no.6
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• pp.350-358
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• 2017

Spill of personal information using a stolen ID and password that recently occurred in large enterprises and portal web site such as Nate, Auction, National Agricultural Cooperative Federation, suggesting the importance of protecting personal information. By managing access to user accounts in real time, users will be able to block access before personal information is leaked. Therefore, In this paper, we propose a method to prevent spill of personal information that may occur when connected to others by using an authorized ID and password from portals. Specifically, we offer a mobile status control app that controls the logged status of user account in real time to view login status information to user by visualization and information about specific time and IP address. Also, we propose a method for detecting and blocking duplicated login that connect via IP address change.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.176-190
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• 2019

The prevention of pedestrian accidents in crosswalks and intersections is very important. The C-ITS services provide a warning service for preventing accidents between cars and pedestrians. In the current pedestrian collision prevention warning service according to the C-ITS standard, however, it is difficult to provide real-time service because it detects pedestrians from a video-analysis server in the control center and sends service messages through the ITS system. This paper proposes a pedestrian collision-prevention warning system that detects pedestrians in the local field using an edge camera and sends a warning message directly to the driver through a roadside unit. An evaluation showed that the proposed system could deliver the pedestrian collision prevention-warning message to the driver satisfying the delay time within the 300 ms required by the C-ITS standard, even in the worst case.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.85-92
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• 2019

Companies can identify user groups or consumption trends by collecting and analyzing opinions of many users on special subjects or their products as well as utilize them as various purposes such as predicting some specific trends or marketing strategies. Therefore current analyzing tools of social media have come into use as a means to measure the performances of social media marketing through network's statistical analysis. However these tools require expensive computing and network resources including burden of costs for building up and operating complex software platforms and much operating know-how. Hence, small companies or private business operators have difficulty in utilizing those social media data effectively. This paper proposes a framework applied into developing analysis system of social media. The framework could be set up and operate the system to extract necessary social media's data. Also to design the system, this study suggests a meta-model of proposed framework and to guarantee completeness and consistency, a formal specification of meta-model by using Z language is suggested. Finally, we could verify the clearness of framework's design by performing Z model checking of formal specification's output through Z-EVES tool.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.1
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• pp.35-45
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• 2007

The log data collected from mobile devices contains diverse meaningful and practical personal information. However, this information is usually ignored because of its limitation of memory capacity, computation power and analysis. We propose a novel method that detects landmarks of meaningful information for users by analyzing the log data in distributed modules to overcome the problems of mobile environment. The proposed method adopts Bayesian probabilistic approach to enhance the inference accuracy under the uncertain environments. The new cooperative modularization technique divides Bayesian network into modules to compute efficiently with limited resources. Experiments with artificial data and real data indicate that the result with artificial data is amount to about 84% precision rate and about 76% recall rate, and that including partial matching with real data is about 89% hitting rate.

• Journal of Internet Computing and Services
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• v.2 no.4
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• pp.41-53
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• 2001

Multi-distributed web cluster model built for high availability E-Business model exposes internal system nodes on its structural characteristics and has a potential that normal job performance is impossible due to the intentional prevention and attack by an illegal third party. Therefore, the security system which protects the structured system nodes and can correspond to the outflow of information from illegal users and unfair service requirements effectively is needed. Therefore the suggested distributed invasion detection system is the technology which detects the illegal requirement or resource access of system node distributed on open network through organic control between SC-Agents based on the shared memory of SC-Server. Distributed invasion detection system performs the examination of job requirement packet using Detection Agent primarily for detecting illegal invasion, observes the job process through monitoring agent when job is progressed and then judges the invasion through close cooperative works with other system nodes when there is access or demand of resource not permitted.

• The Journal of Korean Association of Computer Education
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• v.21 no.2
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• pp.49-58
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• 2018

Competency is an extended concept rather than knowledge and skill, which means the ability to efficiently and rationally solve various problems. This study focuses on the core competencies presented in the 2015 Revised Informatics Curriculum and aims to analyze the constitution method and composition of domestic and overseas Instruments that can measure core competencies. As a result of analyzing 12 Instruments developed by the countries and organizations, nine Instruments measure two or more competencies based on computing thinking, information culture literacy, and cooperative problem solving ability. Three Instruments have one competency were measured. Ten instruments were computer based tests, and 50% of the items were developed by two or more of multiple choice item, subjective item, and descriptive item. It is important to note that this study provided a crucial step in the development of Instruments to diagnose competencies to be developed into informatics science education.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.79-90
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• 2019

As an increasing number of cloud service providers begin to provide cloud computing services, they form a competitive market to compete for users. Due to different resource configurations and service workloads, users may observe different response times for their service requests and experience different levels of service quality. To compete for cloud users, it is crucial for each cloud service provider to determine an optimal price that best corresponds to their service qualities while also guaranteeing maximum profit. To achieve this goal, the underlying rationale and characteristics in this competitive market must be clarified. In this paper, we analyze price competition in the multimedia cloud service market with two service providers. We characterize the nature of non-cooperative games in a duopoly multimedia cloud service market with the goal of capturing how each cloud service provider determines its optimal price to compete with the other and maximize its own profit. To do this, we introduce a queueing model to characterize the service process in a multimedia cloud data center. Based on performance measures of the proposed queueing model, we suggest a price competition problem in a duopoly multimedia cloud service market. By solving this problem, we can obtain the optimal equilibrium prices.