• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.9
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• pp.475-485
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• 2001

A study on the structural analysis of the composite laminated cylindrical shell which has simply supported boundary conditions at both ends, was performed. The results were used into the neural networks. Neural networks identify the load characteristics of the composite shells. Momentum Backpropagation which the learning rate can be varied was developed. Input patterns consist of strains at 9 side points which is divided equally. Output layers are the load characteristics. Developed program was used for the training. The training with variable learning rate was converged close to real oad characteristics. Inverse engineering can be applicable to the composite laminated cylindrical shells with developed neural networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.1022-1032
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• 2012

In OFDMA-based wireless mesh networks, synchronization of carrier frequencies among adjacent nodes is known to be difficult. In this paper, a distributed synchronization technique is proposed to solve the synchronization problem in OFDMA-based wireless mesh networks by using the bio-inspired algorithm. In the proposed approach, carrier frequencies of all nodes in a mesh network are converged into one frequency by locally synchronizing the frequencies of adjacent nodes. It may take a long time to be converged in some topologies since the convergence characteristic of carrier frequencies in a mesh network may vary depending on the size of the network and deployment of nodes. It is shown that fast frequency synchronization, not heavily depending on the topology, can be achieved through the proposed algorithm with an adjustable weight.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.643-646
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• 2005

In this paper, we present a service model which serves multimedia contents to end consumer(End-user) that have various mobile communication terminals under a communication & broadcasting converged environment that broadcasting and communication networks are linked. A main feature of this service model is that it has a distribution structure that deliver to end consumer via adaptation of content from production of contents offering End to End (E2E) media QoS and personalized contents consumption. The proposed service model may be used as a reference model for distribution of multimedia content in communication & broadcasting converged environment in the future.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.136-141
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• 2007

The frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the telecom network. As telecom networks evolve from circuit to packet switching, proper synchronization algorithm should be meditated for IP networks to achieve performance quality comparable to that of legacy circuit-switched networks. The Time of Packet (ToP) specified in IEEE 1588 is able to synchronize distributed clocks with an accuracy of less than one microsecond in packet networks. But, The ToP can be affected by impairments of a network such as packet delay variation. This paper proposes the efficient method to minimize the expectable delay variation when ToP synchronizes the distributed clocks. The simulation results are presented to demonstrate the improved performance case when the efficient ToP transmit algorithm is applied.

• Computers and Concrete
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• v.12 no.3
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• pp.285-301
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• 2013

This paper concentrates on the results of experimental work on tensile strength of self-compacting concrete (SCC) caused by flexure, which is called rupture modulus. The work focused on concrete mixes having water/binder ratios of 0.35 and 0.45, which contained constant total binder contents of 500 $kg/m^3$ and 400 $kg/m^3$, respectively. The concrete mixes had four different dosages of a superplasticizer based on polycarboxylic with and without silica fume. The percentage of silica fume that replaced cement in this research was 10%. Based upon the experimental results, the existing equations for anticipating the rupture modulus of SCC according to its compressive strength were not exact enough. Therefore, it is decided to use artificial neural networks (ANN) for anticipating the rupture modulus of SCC from its compressive strength and workability. The conclusion was that the multi layer perceptron (MLP) networks could predict the tensile strength in all conditions, but radial basis (RB) networks were not exact enough in some circumstances. On the other hand, RB networks were more users friendly and they converged to the final networks quicker.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.475-479
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• 2006

In Korea, we witness vivid evidences of changing trend in communication that insist the emergence of new networking architecture. To accommodate the changing trend and to hold current strong position in global IT industry, Korea have launched broadband convergence network (BcN) initiative. BcN vision for Korea is to be the first in the world to realize converged network infrastructure and ubiquitous service environment. In this paper, we have introduced the concept and the vision of BcN with a viewpoint of a new paradigm to prepare future-proof communication environment. And then, we have disclosed BcN research and development (R&D) activities including R&D philosophy, R&D phases, and key technologies required. Also, we have discussed current development issues in three technology branches including service and control technology, unified transport technology, and next-generation access technology.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.205-215
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• 2008

convergence networks (BcN). The problem seeks to minimize the total cost of switch and cable while satisfying the requirement of demand and quality of service (QoS). We develop mixed integer programming models to obtain the optimal switch location of the access network. We develop a Tabu Search (TS) heuristic algorithm for finding a good feasible solution within a reasonable time limit. We propose real networks with up to 25 nodes and 180 demands. In order to demonstrate the effectiveness of the proposed algorithm, we generate lower bounds from nonlinear QoS relaxation problem. Computational results show that the proposed heuristic algorithm provides upper bounds within 5% optimality gap in 10 seconds.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.3 no.1
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• pp.75-87
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• 2004

The mobile industry is waking up to the reality that customers buy 'services', not technology. Thekey is to deliver a variety of differentiated services today and improve them as the advanced technology becomes available. In the increasingly data centric world of the future, the emphasis will be on the provision of a range of services audio, video, data and multimedia and of course speech. As we move closer to the realization of these mobile services in the conglomeration of converged networks, new challenges are being faced by the technology and application developers as well as the service providers to design, test and integrate new products and services. Functionalities like availability, scalability, performance and compatibility have become more important. This paper discusses the new test paradigms in the mobile networks, both from the applications and the protocols perspective.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.196-201
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• 2010

Measurement of Quality of Service (QoS) parameters and its statistical analysis becomes a key issue for Mobile WiMAX service providers to manage the converged network efficiently and to support end-to-end QoS. In this paper, we investigate the population distribution of end-to-end one-way delay which is the most important QoS parameter in Mobile WiMAX networks. The samples are analyzed with Chi-Square Goodness-of-Fit test, Kolmogorov-Smirnov (K-S), and Anderson-Darling (A-D) test to verify the distribution of parent population. The relation with confidence level and the minimum number of sample size is also performed for logistic distribution. The statistical analysis is a promising approach for measuring the performance Mobile WiMAX networks.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.492-494
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• 1993

CMAC (Cerebeller Model Articulation Controller) is kind of Neural Networks that imitate the human cerebellum. For storage and retrieval of learned data, the input of CMAC is used as a key to determine the memory location. he learned information is distributively stored in physical memory. The learning of CMAC is very fast and converged well, therefore, it effects the application of Pattern Recognition. Through the our experiment of Pattern Recognition, we will prove that CMAC is very suitable for On-line real time processing and incremental learning of Neural Networks.