• Smart Media Journal
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• v.8 no.3
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• pp.41-46
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• 2019

In a MMORPG, a typical application of virtual environment systems, it is a common desire to play in a more realistic environment. However, it is very difficult to provide a latency-free virtual environment to a large user base, mainly due to the fact that the real environment must be configured on multiple servers rather than on single server and that data must be shared on the real server when users move from one region to another. Experiencing response delays continuously in the process of information synchronization between servers greatly deteriorates the degree of immersion. In order to solve this problem, it is necessary to minimize the response delay occurring in the information synchronization process between the servers. In this paper, we propose Migration Agent for efficient information synchronization between field servers providing information of virtual environment and minimizing response delay between Field Server and PC(Player Character) and implement it in cloud computing network. In the proposed system, CPU utilization of field server increased by 6 ~ 13%, and response time decreased by 5 ~ 10 seconds over the existing system in 70,000 ~ 90,000 PCs

• Journal of Internet of Things and Convergence
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• v.9 no.3
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• pp.1-6
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• 2023

One of the economical ways to satisfy the quality of service desired by the user in a web service environment is to adjust the size of the object. To this end, this study finds the maximum size of objects that satisfy this constraint when the mean response time is given below an arbitrary threshold for quality of service. It can be inferred that in the steady state of system, the mean response time in the deterministic model by using the round-robin will be the same as that of the queueing model following the general distribution. Based on this, analytical formulas and procedures for finding the maximum object size are obtained. As a service distribution of web traffic, the Pareto distribution is appropriate, so the maximum object size is computed by applying the M/G(Pareto)/1 model and the M/G/1/PS model using exponential distribution as computational experience. Performance evaluation through numerical calculation shows that as the shape parameter in the Pareto distribution increases, the M/G(Pareto)/1 model and M/G/1/PS model have the same maximum object size. The results of this study can be used to environments where objects can be sized for economical web service control.

• Journal of Digital Convergence
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• v.11 no.2
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• pp.279-285
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• 2013

The development of information networks and computer technology has become a foundation to open up a sea of information and knowledge. The recent popularization of smart devices has been used as a tool to easily obtain the desired information and knowledge. In this paper, a knowledge-sharing system using information and social networks based on smart devices is proposed. The proposed system consists of functions of an Internet information search for user queries, accumulated knowledge, and social network response from acquaintances. An evaluation for user satisfaction was conducted to analyze the efficacy of the proposed system. According to the experiment, the knowledge-sharing system using smart device information results in significant satisfaction compared to the general information search engines.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.6
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• pp.205-212
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• 2015

SSH provides a secure, encrypted communication channel between two end point systems using public key encryption. But SSH brute force attack is one of the most significant attacks. This kind of attack aims to login to the SSH server by continually guessing a large number of user account and password combinations. In this paper, we analyze logs of SSH brute force attacks in 2014 and propose a failed-log based detection mechanism in high performance computing service environment.

• Journal of Information Technology Services
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• v.12 no.4
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• pp.267-287
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• 2013

As the online bookstore market has been saturated and the level of competition has become more intense, maintaining competitive advantage by mitigating consumers' perceived risks can be considered as one of good alternative strategies a company should use. Although studies that identify the types of consumers' perceived risks in the context of online bookstores as well as validate the relationships between perceived risk and its antecedent/consequent factors in an integrated manner are strongly required, there has been less attention paid to these matters. Therefore, based on previous literature, we identify five types of perceived risks (financial, performance, online payment, delivery, and seller's response risk) and validate the impacts of online bookstore specific characteristics and user specific characteristics on perceived risk. In addition, we also verify causal relationship between perceived risk and intention to use online bookstores. The results of PLS test using 108 samples collected from undergraduate and graduate students confirm that perceived risk has a negative impact on intention to use and four antecedents (reputation, service quality, self-efficacy, and user experience) are significantly related to perceived risk.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.107-116
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• 2005

The paper addresses modeling and analysis of a grid-connected photovoltaic generation system (PV system). PSCAD/EMTDC, an industry standard simulation tool for studying the transient behavior of electric power system and apparatus, is used to conduct all aspects of model implementation and to carry out extensive simulation study. This paper is aimed at sharing with the PSCAD/EMTDC user community our user-defined model for PV system applications, which is not yet available as a standard model within PSCAD/EMTDC. An equivalent circuit model of a solar cell has been used for modeling solar array. A series of parameters required for array modeling have been estimated from general specification data of a solar module. A PWM voltage source inverter (VSI) and its current control scheme have been implemented. A maximum power point tracking (MPPT) technique is employed for drawing the maximum available energy from the PV array. Comprehensive simulation results are presented to examine PV array behaviors and PV system control performance in response to irradiation changes. In addition, dynamic responses of PV array and system to network fault conditions are simulated and analysed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.99-108
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• 2010

RFID(Radio Frequency IDentification) is a technology that automatically identifies objects containing the electronic tags by using radio wave. When there are some tags in the domain of the RFID reader, the mechanism that can solve a collision between the tags occurs is necessary. The multi tag identification problem is the core issue in the RFID and could be resolved by the anti-collision algorithm. However, RFID system has another problem. The problem id user information security. Tag response easily by query of reader, so the system happened user privacy violent problem by tag information exposure. In the case, RFID system id weak from sniffing by outside. In this paper, We study of security robustness for tree-walking algorithm, query tree algorithm and advanced query tree algorithm of tree based memoryless algorithm.

• Korean Journal of Computational Design and Engineering
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• v.13 no.1
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• pp.8-17
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• 2008

Putting a high value on individual preferences is a modern trend that more and more companies are considering for their product design and development and the apartment design is not an exception. Most apartments today are built using similar design with no room for customization. People in general want their tastes to be reflected in the design of their apartment. However, delivering what customers like to the construction company may not be an easy task in practice. For this reason, an intuitive and effective medium between the company and customers for effective communication is needed to ameliorate such a difficulty and in response to this necessity, we developed a test platform for the virtual model house which provides a user with the customization of the apartment using haptic interactions. In our virtual environment, a user can explore an apartment and change the interior based on their taste and feel through intuitive haptic interactions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1572-1580
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• 2010

This thesis presents an emotion-based contents player platform that can change its visual and aural components as user's emotions. It analyzes the emotion as pleasant, unpleasant, aroused, and relaxed based on the physiological signals and the user's active response. Accordingly. the system reorganizes graphical and aural stimuli, such as, light, color, sound, in real-time. It can be used to develop and show the emotional contents and also be applied for the systematic analysis to find out how the components would affect the emotion. This paper describes overall the system architecture and the implementations of the sub-systems, as well as the actual contents built on top of the platform.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.111-118
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• 2008

RIA(Rich Internet Application) has the best User Interface and easy way to use. It is used in many Application System and Web Application. This Paper introduces a RIA technology for Implementation of u-Hospital Application. This System uses a history of customers in the hospital and question about diseases, so we can improve the satisfaction of service. This paper shows that the u-Hospital System using RIA is more fast and easy than HTML application. Because RIA has special features that data can be obtained from server without reloading entire page and every user interaction does not require web server response. The proposed technology can improve the efficient u-Hospital System because it can be extended to ubiquitous mobile application.