• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4873-4888
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• 2018

A joint blind parameter estimation algorithm based on minimum channel stability function aimed at the non-cooperative high-order modulated paired carrier multiple access (PCMA) signals is proposed. The method, which uses hierarchical search to estimate time delay, amplitude and frequency offset and the estimation of phase offset, including finite ambiguity, is presented simultaneously based on the derivation of the channel stability function. In this work, the structure of hierarchical iterative processing is used to enhance the performance of the algorithm, and the improved algorithm is used to reduce complexity. Compared with existing data-aided algorithms, this algorithm does not require a priori information. Therefore, it has significant advantage in solving the problem of blind parameter estimation of non-cooperative high-order modulated PCMA signals. Simulation results show the performance of the proposed algorithm is similar to the modified Cramer-Rao bound (MCRB) when the signal-to-noise ratio is larger than 16 dB. The simulation results also verify the practicality of the proposed algorithm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.64-72
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• 2003

Comparing with transmission networks, the faults in distribution networks more often occurs because of the complicated structure and the adjacency to customers. Moreover the faults give direct damage to customers. So fault diagnosis and blackout restoration in distribution networks are very important elements to reduce the damage of customers and to maintain the stability. The restoration problem of distribution networks is subject to time. Minimizing the switching numbers in restoration process is the crucial element. In other words. the best restoration is to restore all blackout area through just one switching, if not the restoration has to be accomplished through several switching. This paper proposes the efficient restoration system in distribution networks to minimize the switching numbers. The proposed system uses the dynamic division method of hierarchical structure which consists of heuristic searching method and meta algorithm. The proposed system is applied to the sample networks, and the results showed a promising possibility.

• Journal of Korean Academy of Nursing Administration
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• v.17 no.4
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• pp.432-442
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• 2011

Purpose: The purpose of this study was to identify the factors influencing the intention of the reuse in patients admitted in university hospital emergency medical center. Method: The participants were 253 patients admitted to a niversity hospital emergency medical center. Data were collected with self-administrated questionnaires and analyzed by hierarchical multiple regression. Results: Patient satisfaction with nursing care service and switching cost were positively correlated with reuse by patients while the perceived risk was negatively correlated. As levels of satisfaction with nursing care services and switching cost increase, intention of reuse increases. Satisfaction with nursing care service, switching cost and perceived risk in emergency medical center influence intention to reuse and explain 68.8% of total variation of intention to reuse. Conclusion: Findings provide strong empirical evidence for importance of atient satisfaction with nursing care service, the switching costs and the perceived risk in explaining the intention of reuse an emergency medical center.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.458-463
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• 1998

This paper presents an autopilot design method for STT missiles using the intelligent control technique and multiple controllers. The mixed $H_2/H_{\infty}$ control technique is applied for each controller design and the control gains are implemented by using the genetic searching algorithm. To facilitate automatic switching of multiple controllers under different operating conditions, an error based switching scheme is also combined with the multiple controllers at a higher level, which constitutes a hierarchical intelligent control system. It is shown via computer simulation that the proposed autopilot outperforms the conventional one.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.6
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• pp.43-51
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• 1983

A small-scale packet switching system is designed in compliance with the CCITT Recommen-dation X.25 Each switching node is controlled by a single microcomputer for all functions including terminal access control, packet-level control and link control. Basic protocol functions are successfdly implemented for the three basic hierarchical Igvels, and their results are discussed in detail.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.1
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• pp.43-50
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• 1989

In this paper we present a new approach to control system design for multivariable systems using a sliding mode. In the applications of variable structure system (VSS) theory to multivariable systems, there exist some difficulties such as how to determine switching gains and how to reduce chattering phenomena in input and state trajectories. To cope with these drawbacks we introduce switching dynamics instead of switching logics to obtain the sliding mode. Consequently, we can obtain the new design approach which is much simpler than the VSS theory, And there do not exist chattering phenomena in this method because the obtained control inputs are continuous. Hierarchical control concepts are used to the control system design. Numerical examples are discussed as illustrations.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.163-166
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• 2003

In recent years, there has been increased to access multimedia service through the Internet due to rise of the access speed. We suppose the co-existence of the various access networks in adjacent area in the future, such as wireless LAN, Bluetooth, and 3G Cellular So, the size of the cell will be smaller and the number of access point will be increased. In other words, the potable devices need the efficient mobility scheme due to move between cells frequently Currently, the several of the scheme, which is Cellular IP, HAWAII, Mobile IPv4 regional registration, and hierarchical Mobile IPv6, is suggested to support micro-mobility but Mobile IPv4 is standard scheme to support the mobility of the mobile node. MPLS, which forwards the packet through switching instead of routing using IP address, has begun to deploy in the internet backbone to increase the performance of mobility protocol. The integration of both MPLS and Mobile IP improves the scalability of the Mobile IP data forwarding process by leveraging on the features MPLS which are fast switching and high scalability. Moreover it abbreviates IP-in-IP tunneling between HA and FA. In this paper, we suggest efficient mobility scheme through integration of both MPLS and hierarchical Mobile IPv6.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.145-164
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• 2014

Network virtualization provides a promising tool to allow multiple heterogeneous virtual networks to run on a shared substrate network simultaneously. A long-standing challenge in network virtualization is the Virtual Network Embedding (VNE) problem: how to embed virtual networks onto specific physical nodes and links in the substrate network effectively. Recent research presents several heuristic algorithms that only consider single topological attribute of networks, which may lead to decreased utilization of resources. In this paper, we introduce six complementary characteristics that reflect different topological attributes, and propose three topology-aware VNE algorithms by leveraging the respective advantages of different characteristics. In addition, a new KS-core decomposition algorithm based on two characteristics is devised to better disentangle the hierarchical topological structure of virtual networks. Due to the overall consideration of topological attributes of substrate and virtual networks by using multiple characteristics, our study better coordinates node and link embedding. Extensive simulations demonstrate that our proposed algorithms improve the long-term average revenue, acceptance ratio, and revenue/cost ratio compared to previous algorithms.

• The Journal of the Korea Contents Association
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• v.12 no.10
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• pp.453-465
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• 2012

The major purpose of this study is to examine the effects of customers' perceptions toward service quality of mobile music service on customer loyalty and switching intention. For this purpose, this study posited three service quality characteristics including interface, service, price quality as key determinants of customer loyalty and switching intention based on relevant literature reviews. A research model and hypotheses concerning the relationship between these variables were constructed. Moreover, this study explored the moderating effects of attractiveness of alternative and switching costs on the relationship between customer loyalty and switching intention. An online survey was administrated on 433 mobile music service users and a simple, multiple, and hierarchical regression analysis were employed. The results indicated that all of interface, service, price quality have significant positive influences on customer loyalty, and both of service quality and attractiveness of alternatives have influences on the switching intention in a positive way. On the other way, it was shown that switching costs have a negative influence on the switching intention. The moderating effect of attractiveness of alternatives on the relationship between customer loyalty and switching intention was also found. The implications of these results are discussed.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.761-763
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• 1997

As the power system network is enlarged and complicated gradually, the automation of power system network is essential to enhance the reliability and performance of the operation of power system. Distribution restoration is a major part of the automation. This paper proposes a new distribution restoration system to restore healthy blackout regions by the hierarchical cooperation with the substation automation systems. In proposed system, the range of restoration is extended to substations and the performance as well as the switching efficiency of restoration system is enhanced.