• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.50-59
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• 2006

The new communication paradigm is rapidly shifted from wireless mobile networks to an All-IP(Internet Protocol) network, led by service industry leaders and communication manufacturers. In this paradigm, providing authentication and session keys of a subscriber becomes one of the critical tasks because of IP open accessibility among heterogeneous networks. In this paper, we introduce authentication process procedure of heterogeneous wireless mobile networks and develop so-called IMAS(Integrated Mobile Authentication Server) which can securely inter-work among all mobile networks and support the legacy networks with backward compatibility. Especially, in designing IMAS, mobile authentication inter-working mechanism, key management technique, and other issues to be overcome are presented. We analyze and evaluate the performance of authentication algorithm which creates session key. A simulation environment of IMAS is established, and a performance(TPS; Transaction Per Second) result is analyzed and evaluated. It turned out that IMAS works among heterogeneous wireless mobile networks without compensating efficiency and functionalities of the legacy networks and decrease the entropy of data redundancy and data inconsistency among networks because of the integrity of the distributed Data Base(DB).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3C
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• pp.233-240
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• 2012

Unlike traditional factory environment, in an industrial factory network applied wireless sensor network technologies, all procedures of discovery, identification and verification of devices should be performed in an automatic fashion. To address these challenges, we design a management system using the device registry server that we propose in this paper. In the phase of device discovery, the proposed system utilizes properties of routing protocol running in factories. Also, in the phase of identification and verification, the system uses unique and general information of a device stored within the device registration server. Such a way allows management system to reduce implementation complexity and to easily manage devices in a factory applied with a wireless network consisting of heterogeneous devices.

• Journal of Korean Library and Information Science Society
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• v.34 no.4
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• pp.1-20
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• 2003

Through analyzing papers on digital libraries and the contexts of usage of the term, ‘digital library’, this study investigates that the professional discourses about digital libraries regard them digital technologies. But digital libraries need to be recognized as socio-technical networks which are constructed by social interaction between heterogeneous elements. The study suggested that Social Informatics and a STIN(Socio-Technical Interaction Network) model should be applied to understand and analyze digital libraries as socio-technical networks.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1355-1358
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• 2001

IP Multicast can efficiently provide enormous bandwidth savings by enabling sources to send a single copy of a message to multiple recipients who explicitly want to receive the information. But due to the complexity of IP multicast and its fundamental differences from unicast, there are not very many tools available fer monitoring and debugging multicast networks, and only a few experts understand the tools that do exist. This thesis proposes a Multicast Routing Debugger (MRD) system that monitor the status of a multicast network. This system is aimed to multicast-related faults detection. In thesis, first, we define the set of information that should be monitored. Second, the method is developed to take out such information from multicast routers. Third, MRD system is prototyped to collect, process information from heterogeneous routers on a multicast network and to display the various status of the network comprehensively. The prototype of MRD system is implemented and deployed. We perform experiments with several scenarios. Experimental results show we can detect various problems as information that we define is monitored. The MRD system is simple to use, web-based and intuitive tool that can monitor the status of a specific multicast network.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.522-522
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• 2006

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2014-2034
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• 2015

This paper focuses on solving co-channel interference (CCI) issues arising in the open subscriber group (OSG) mode of heterogeneous networks (HetNets). Considering a general framework consisting of arbitrary number of picocells within a macro cell, where the inter-user interference (IUI) is the main CCI to macro user equipments (UEs), while the the inter-cell interference (ICI) is the major CCI to pico UEs. In this paper, three IA based transceiver design schemes are proposed. For macro cell, we uniformly use block diagonalization (BD) scheme to eliminate the IUI. And for picocells, three IA schemes are proposed to mitigate the ICI. The first scheme, named as zero forcing IA (ZF-IA) scheme, aligns the inter picocell interference onto an arbitrary sub-space of the cross-tier interference using ZF scheme. Considering the channel state information (CSI) of the desired channel of pico UEs, the second scheme, named as optimal desired sub-channel selected IA (ODC-IA) scheme, aligns the inter picocell interference onto a certain sub-space of the cross-tier interference, which guarantees the largest channel gain of the desired signal of pico UEs. The third IA scheme, named as maximum cross-tier interference selected IA (MI-IA) scheme, is designed for the system with less receive antennas. The inter picocell interference is aligned onto the space of the strongest cross-tier interference and only the interference on this space is nullified. The complexity analysis and simulations show that the proposed transceiver design schemes outperform the existing IA schemes in the OSG mode of HetNets, and the MI-IA scheme reduces the requirement of the receive antennas number with lower complexity.

• International journal of advanced smart convergence
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• v.5 no.1
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• pp.59-65
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• 2016

In this paper, we're compared network protocol which is network lifetime longer when using LEACH Protocol, SEP, and TEEN in a heterogeneous Wireless Sensor Network with a Large Sensor Area. Also, we propose a method of divided layer the wide-area sensor filed and transmitting a multi-hop to improve the network lifetime. And we're compared network protocol which is network lifetime more improved apply the proposed method to LEACH Protocol, SEP, and TEEN. We tried to compare results, TEEN showed the best network lifetime. Apply the proposed method to divided the sensor field, L-TEEN (Layered TEEN)'s network lifetime rates of improvement is highest.

• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.119-134
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• 2001

This paper proposed a dynamic transit vehicle simulation model and a dynamic transit passengers simulation model, which can simultaneously simulate the transit vehicles and passengers traveling on a transit network, and also developed an algorithm of dynamic departure time choice model based on individual passenger. The proposed model assumes that each passenger's behavior is heterogeneous based on stochastic process by relaxing the assumption of homogeneity among passengers and travelers have imperfect information and bounded rationality to more actually represent and to simulate each passenger's behavior. The proposed model integrated a inference and preference reforming procedure into the learning and decision making process in order to describe and to analyze the departure time choices of transit passengers. To analyze and evaluate the model an example transit line heading for work place was used. Numerical results indicated that in the model based on heterogeneous passengers the travelers' preference influenced more seriously on the departure time choice behavior, while in the model based on homogeneous passengers it does not. The results based on homogeneous passengers seemed to be unrealistic in the view of rational behavior. These results imply that the aggregated travel demand models such as the traditional network assignment models based on user equilibrium, assuming perfect information on the network, homogeneity and rationality, might be different from the real dynamic travel demand patterns occurred on actual network.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.28-37
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• 2017

Multipath TCP (MPTCP), which is a layer 4 protocol that can get the reliability and the efficiency of the transmission by using multipath transfer, was standardized by the IETF. MPTCP provides superior performance when compared to a single TCP when used in a homogeneous network with similar network characteristics. However, MPTCP degrades performance when used in heterogeneous networks with different network characteristics. In this paper, we propose 'Delay-alerted path-blocking scheduler'. It measures the delay of each path and blocks the path with a long delay to reduce the order of packets in the receive buffer. If the duplicated packet is sent to the blocked path to measure the delay and the congestion on the blocking path is reduced, the blocked path is unblocked. For performance analysis, the proposed scheduler was implemented in the Linux kernel and improved performance was obtained in the test bed. We also confirmed that the proposed scheduler reduces the degradation of MPTCP performance in real wireless networks with heterogeneous path characteristics.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.10-23
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• 2009

In this paper we propose a novel mobile terminal software architecture supporting energy efficient handover operation in heterogeneous networks. Since the legacy proposals for L3 handover are mostly dependent on IETF Mobile IP which has some problems in movement detection mechanism and no considerations on nested heterogeneous network environment as a result they make serious overload on networks and terminals by performing unnecessary handover in such network environments. The proposed architecture has terminal-oriented network selection and switching architecture where a mobile terminal periodically monitors network status and selects the optimum network, and reduces energy consumption by making L3 handover of Mobile IP to the finally selected network. The network selection method first picks up some candidate networks by considering a terminal speed and power consumption estimation, and determines the final target handover network among the candidates after evaluating multiple factors including QoS required by a terminal, network status, user preference and terminal battery status. Finally we verify the functionality and performance of the energy efficient vertical handover architecture by means of adopting it into a real mobile terminal.