• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.84-90
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• 2011

Handling paging mechanism at the IP layer (i.e., IP paging) makes it possible to support heterogeneous wireless access technologies, providing energy-saving and reduced location registration signaling overhead over IP-based mobile networks. However, IP paging may rather cause adverse effects under active communication environments because of significant paging signaling overhead and frequent paging delay. Therefore, in order to solve these problems, a cost-effective IP paging scheme is proposed in this paper, which enables a mobile node to perform selective registration and paging based on its profile information. Numerical results indicate that the proposed scheme has apparent potential to mitigate considerable paging signaling overhead and frequent paging delay in IP-based hierarchical mobile networks.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.5
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• pp.196-208
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• 2005

In multiprocessor systems, interconnection network design is critical for overall system performance. Popular interconnection networks, which are generally considered, are meshes, rings, and hierarchical rings. In this paper, we propose (')Torus Ring('), which is a modified version of hierarchical ring. Torus Ring has the same complexity as the hierarchical rings, but the only difference is the way it connects the local rings. It has an advantage over the hierarchical rings when the destination of a packet is the neighbor local ring in the reverse direction. Though the average number of hops in Torus Ring is equal to that of the hierarchical rings when assuming the uniform distribution of each transaction, the benefits of the number of hops are expected to be larger because of the spatial locality in the real environment of parallel programming. In the simulation results, latencies in the interconnection network are reduced by up to 19$\%$, and the execution times are reduced by up to 10$\%$.

• Journal of the Korea Society for Simulation
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• v.9 no.2
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• pp.1-14
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• 2000

Recently, as construction of information infra including high-speed communication networks remarkably expands, more various information services have been provided. Thus the number of internet users rapidly increases, and it results in heavy load on Web server and higher traffics on networks. The phenomena cause longer response time that means worse quality of service. To solve such problems, much effort has been attempted to loosen bottleneck on Web server, reduce traffic on networks and shorten response times by caching informations being accessed more frequently at the proxy server that is located near to clients. And it is also possible to improve internet performance further by allowing clients to share informations stored in proxy caches. In this paper, we perform simulations of hierarchical proxy caches with the 3-level 4-ary tree structure by using real web traces, and analyze cache hit ratio for various cache replacement policies and cache sizes when the delayed-store scheme is applied. According to simulation results, the delayed-store scheme increases the remote cache hit ratio, that improves quality of service by shortening the service response time.

• ETRI Journal
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• v.28 no.5
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• pp.631-637
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• 2006

In this paper we study the optimization issues of ring networks employing novel parallel multi-granularity hierarchical optical add-drop multiplexers (OADMs). In particular, we attempt to minimize the number of control elements for the off-line case. We present an integer linear programming formulation to obtain the lower bound in optimization, and propose an efficient heuristic algorithm called global bandwidth resource assignment that is suitable for the design of large-scale OADM networks.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.427-440
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• 1996

Constraint networks are a major approach to knowledge representation in Concurrent Engineering (CE) systems. The networks model various factors in CE as constraints linked by shared variables. Many systems have been developed to assist constraint network processing. While these systems can be useful, their underlying assumption that a solution must simultaneously satisfy all the constraints is often unrealistic and hard to achieve. Proposed in this paper is a hierarchical representation of constraint networks using priorities, namely Prioritized Constraint Network (PCN). A mechanism to propagate priorities is developed, and a new satisfiability definition taking into account the priorities is described. Strength of constraint supporters can be derived from the propagated priorities. Several properties useful for investigating PCN's and finding effective solving strategies ore developed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.476-483
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• 2009

Recently much attention has been devoted to femtocell's potential to improve indoor cellular coverage and high speed wireless communications. Femtocell based commercial services have been already launched in some countries and standardization activities are actively on-going, there has been concern however over potential issues of interference between femtocells and the micro/macro networks. With universal frequency reuse, the ensuing cross-tier interference causes unacceptable data rate and outage probability, so an analysis of effect of interference in femtocell embedded networks would be necessary for a stable system design. This paper investigates the effect of interference on system performances of femtocell embedded hierarchical cell structure (HCS) networks considering the characteristics of propagation environments. Various channel parameters are specially considered for indoor environments where most of femtocells are deployed to investigate the effect of interference of femtocell embedded RCS networks. System capacity and coverage are provided with variant distance between macrocell and femtocell, location of the user in femtocell coverage, and characteristic of building structures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1B
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• pp.48-57
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• 2008

Wireless sensor networks are composed of a lot of sensor nodes and they are used to monitor environments. Since many studies on wireless sensor networks have considered a stationary sink node, they cannot provide fully ubiquitous applications based on a mobile sink node. In those applications, routing paths for a mobile sink node should be updated while a sink node moves in order to deliver sensor data without data loss. In this paper, we propose a method to continuously update routing paths for a mobile sink node which can be extended on hierarchical multi-hop routing protocols in wireless sensor networks. The efficiency of the proposed scheme has been validated through comparing existing method using a location based routing protocol by extensive computer simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.997-1010
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• 2014

Today, as the hierarchical cellular system is getting more attention than before, some recent studies introduce delay based admission control (AC) scheme which delays the admission to the macro-embedded small cell for a relatively short time to prevent unnecessary handover caused by the short-term visitors of the small cell area. In such delay based ACs, when we use improper delay parameter, the system frequently makes incorrect handover decisions such as where unnecessary handover is allowed due to too short delaying, or where necessary handover is denied due to too long delaying. In order to avoid these undesirable situations as much as possible, we develop a new delay parameter decision method based on probabilistic cell residence time approximations. By the extensive numerical and analytical evaluations, we determine the proper delay parameter which prevents the incorrect handover decision as much as possible. We expect our delay parameter decision method can be useful system administration tips in hierarchical cellular system where delay based AC is adopted.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.201-209
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• 2017

This paper is a smartphone object recognition system using hierarchical convolutional neural network. The overall configuration is a method of communicating object information to the smartphone by matching the collected data by connecting the smartphone and the server and recognizing the object to the convergence neural network in the server. It is also compared to a hierarchical convolutional neural network and a fractional convolutional neural network. Hierarchical convolutional neural networks have 88% accuracy, fractional convolutional neural networks have 73% accuracy and 15%p performance improvement. Based on this, it shows possibility of expansion of T-Commerce market connected with smartphone and broadcasting media.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4644-4661
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• 2015

Wireless sensor networks are often organized in the form of clusters leading to the new framework of WSN called cluster or hierarchical WSN where each cluster head is responsible for its own cluster and its members. These hierarchical WSN are prone to various routing layer attacks such as Black hole, Gray hole, Sybil, Wormhole, Flooding etc. These routing layer attacks try to spoof, falsify or drop the packets during the packet routing process. They may even flood the network with unwanted data packets. If one cluster head is captured and made malicious, the entire cluster member nodes beneath the cluster get affected. On the other hand if the cluster member nodes are malicious, due to the broadcast wireless communication between all the source nodes it can disrupt the entire cluster functions. Thereby a scheme which can detect both the malicious cluster member and cluster head is the current need. Abnormal energy consumption of nodes is used to identify the malicious activity. To serve this purpose a learning based energy prediction algorithm is proposed. Thus a two level energy prediction based intrusion detection scheme to detect the malicious cluster head and cluster member is proposed and simulations were carried out using NS2-Mannasim framework. Simulation results achieved good detection ratio and less false positive.