• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.79-87
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• 1999

For its simplicity and cost effectiveness in implementation, the Inverted DGPS is well suited for some specific applications like automatic vehicle location systems, where the monitoring station needs accurate position of the vehicles in the street. In the Inverted DGPS, the user sends its GPS position and associated satellite informations to the reference station, and the corrections are made at the reference station to get differentially corrected user position. A fundamental requirement in IDGPS is that the user and the reference station must use the same satellites when the corrections are made. But in practice, it is not often satisfied. Inverted DGPS is also suffered from performance degradation as the baseline become large like DGPS. IDGPS system using multi-reference station can resolve this problem. In this paper a simple multi-reference IDGPS algorithm is proposed and some experiments and analysis are peformed. Experiment results show that IDGPS can achieve the positioning performance as accurate as the DGPS can provide.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.828-834
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• 2010

In this paper, an adaptive cross-layer resource allocation algorithm for the downlink multi-user OFDM system is proposed. The proposed algorithm does not only concern the wireless characteristics of physical (PHY) layer, but also pays attention to the user's quality of service (QoS) requirement, fairness, and packet queue state information of medium access control (MAC) layer. The algorithm is composed of two parts: one is to decide the priority of the user, and the other is to assign the radio resource according to its priority. Simulation results show that the proposed algorithm has both steady QoS and low computation complexity, even though the mobile users have different receiving signal to noise ratio (SNR).

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.3
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• pp.168-174
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• 2010

User authentication is an important requirement to provide secure network service. Therefore, many authentication schemes have been proposed to provide secure authentication, such as key agreement and anonymity. However, authority of scheme is limited to one's self. It is inefficient when authenticated users grant a certification to other users who are in an organization which has a hierarchical structure, such as a company or school. In this paper, we propose the first authentication scheme to use Attributes-Based Re-encryption that creates a certification to other users with specified attributes. The scheme, which has expanded from Rhee et al. scheme, has optimized computation performance on a smart card, ensuring the user's anonymity and key agreement between users and server.

• The Journal of Information Systems
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• v.18 no.3
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• pp.231-249
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• 2009

Recently, plant construction industries are enjoying a favorable business climate centering around developing countries and oil producing countries rich in oil money. This paper proposes a methodology of implementing case-based reasoning(CBR) system for managing knowledge like lessons learned and various documents accumulated in performing power plant construction projects which are receiving a lot of order from foreign countries such as the Middle East, etc. Our methodology is consisted of 10 steps : user requirement gathering, information modeling, case modeling, case base design, similarity function design, user interface design, case base building, CBR module development, user interface implementation, integration test. Also, to illustrate the effectiveness of proposed methodology, the real CBR system is implemented for the plant business division of 'H' company which has international competitiveness in the field of plant construction industry. At present, the implemented CBR system is successfully utilizing as storing, sharing, and reusing knowledge which is accumulated in performing power plant construction projects in the target enterprise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2086-2097
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• 2012

A terminal-based dynamic clustering algorithm is proposed in a multi-cell scenario, where the user could select the cooperative BSs from the predetermined static base stations (BSs) set based on dynamic channel condition. First, the user transmission rate is derived based on linear precoding and per-cell feedback scheme. Then, the dynamic clustering algorithm can be implemented based on two criteria: (a) the transmission rate should meet the user requirement for quality of service (QoS); (b) the rate increment exceeds the predetermined constant threshold. By adopting random vector quantization (RVQ), the optimized number of cooperative BSs and the corresponding channel conditions are presented respectively. Numerical results are given and show that the performance of the proposed method can improve the system resources utilization effectively.

• Proceedings of the Safety Management and Science Conference
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• 2005.05a
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• pp.453-459
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• 2005

On this research, we show some concrete examples as software design, 2D/3D display, graph display, and gage display to develop a data monitoring system for real time safe fire testing. Developed software which is simulation software for live fire testing, has been designed to display informations about whole test status in a live fire testing, and with this, user can control a live fire testing under the safe environment. Beside, we increase a security by using a authority of user to access on this software. and we develop it based on module designed to apply a requirement of user later on.

• Journal of International Society for Simulation Surgery
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• v.2 no.1
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• pp.40-42
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• 2015

Purpose Usability is an important factor in our life. This paper presents an approach to design the clinical work-flow for ultrasound system. And, we tried to apply this work-flow in diagnosis ultrasound system. Materials and Methods For user learnability, we follow international standard IEC 60601-1-1 and IEC 62366 which describes usability of medical instrument. User requirement are applied by 10 clinicians who are well aware of usability. We considered user environment and designed clinical work-flow into two types: general use and emergency use. The designed clinical work-flow was evaluated by 10 clinicians and results derived from the evaluation were analyzed. Results We could successfully design optimized clinical workflow of ultrasound system. Conclusion This paper suggests usability testing for optimized ultrasound clinical workflow. Using this clinical work flow, users can enhance their clinical performance and reduce operation time.

• Journal of the Korea Safety Management & Science
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• v.7 no.2
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• pp.65-72
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• 2005

On this research, we show some concrete examples as software design, 2D/3D display, graph display, and gage display to develop a data monitoring system for real time safe fire testing. Developed software which is simulation software for live fire testing, has been designed to display informations about whole test status in a live fire testing, and with this, user can control a live fire testing under the safe environment. Beside, we increase a security by using a authority of user to access on this software. and we develop it based on module designed to apply a requirement of user later on.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.287-304
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• 2012

Spectrum sensing is an important functionality for cognitive users to look for spectrum holes before taking transmission in dynamic spectrum access model. Unlike previous works that assume perfect knowledge of the SNR of the signal received from the primary user, in this paper we consider a realistic case where the SNR of the primary user's signal is unknown to both fusion center and cognitive radio terminals. A Kalman filter based adaptive Takagi and Sugeno's fuzzy system is designed to make the global spectrum sensing decision based on the observed energies from cognitive users. With the capacity of adapting system parameters, the fusion center can make a global sensing decision reliably without any requirement of channel state information, prior knowledge and prior probabilities of the primary user's signal. Numerical results prove that the sensing performance of the proposed scheme outperforms the performance of the equal gain combination based scheme, and matches the performance of the optimal soft combination scheme.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.767-770
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• 2015

With the deployment of web-based educational game over the internet, the user's registration becomes a critical element. The user is authenticated by the system using username, password, and unique code. However, it cannot be handled properly because the data is transmitted through insecure channel on the network. Hence, security requirement is needed to avoid identity leakage from malicious user. In this paper, we propose a secure communication approach using SSL protocol for an online game. We also describe the security requirements for our approach. In future work, we intend to configure and implement the SSL protocol by enabling HTTPS in web-based online game.