• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.241-269
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• 2012

Wireless networks composed of multimedia-enabled resource-constrained sensor nodes have enriched a large set of monitoring sensing applications. In such communication scenario, however, new challenges in data transmission and energy-efficiency have arisen due to the stringent requirements of those sensor networks. Generally, congested nodes may deplete the energy of the active congested paths toward the sink and incur in undesired communication delay and packet dropping, while bit errors during transmission may negatively impact the end-to-end quality of the received data. Many approaches have been proposed to face congestion and provide reliable communications in wireless sensor networks, usually employing some transport protocol that address one or both of these issues. Nevertheless, due to the unique characteristics of multimedia-based wireless sensor networks, notably minimum bandwidth demand, bounded delay and reduced energy consumption requirement, communication protocols from traditional scalar wireless sensor networks are not suitable for multimedia sensor networks. In the last decade, such requirements have fostered research in adapting existing protocols or proposing new protocols from scratch. We survey the state of the art of transport protocols for wireless multimedia sensor networks, addressing the recent developments and proposed strategies for congestion control and loss recovery. Future research directions are also discussed, outlining the remaining challenges and promising investigation areas.

• Computational Structural Engineering
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• v.10 no.2
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• pp.265-272
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• 1997

The purpose of this paper is to develop Neural Network models for Approximate Structural Analysis (NNASA). As an initial stage, the paper classifies the characteristics and the active role of neural networks in the numerical analysis by comparing neural networks with conventional numerical analysis algorithms. The paper proposed two methods of finding solutions of linear algebraic equations by a modified neural network algorithm, and presents that multilayer feedforward networks are a class of universal approximators by comparing the neural network with regression and interpolation techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.4 no.1
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• pp.25-31
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• 1979

All the resitors in the active RC filter networks can be relplaced by the switched capacitors. Therefore, An SC filter circuit can be fully integrated using MOS technology. A switched capacitor is much better than a resistor in temperature and linearity characteristics, and the former can be fabricated on the much smaller area then the latter. In this paper, It is given the generalized disign method of the active SC filter from the active RC filter using Bilinear Z-transformation. By SC filtering Techniques using Bilinear Z-transform, It enalbes us to realize the FDNR and Gyrator filters, which could not be realized in the exsisting designs, and it permits the processing of signals at much higher frequenies that many previous designs do. Experiments show that the response of the SC active filter is similiar to that of its prototype active RC filter.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.1904-1921
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• 2019

In this paper, we investigate the problem of secure communications in multiple-input-multiple-output interference networks from the perspective of physical layer security. Specifically, the legitimate transmitter-receiver pairs are divided into different categories of active and inactive. To enhance the security performances of active pairs, inactive pairs serve as cooperative jammers and broadcast artificial noises to interfere with the eavesdropper. Besides, active pairs improve their own security by using joint transceivers. The encoding of active pairs and inactive pairs are designed by maximizing the difference of mean-squared errors between active pairs and the eavesdropper. In detail, the transmit precoder matrices of active pairs and inactive pairs are solved according to game theory and linear programming respectively. Experimental results show that the proposed algorithm has fast convergence speed, and the security performances in different scenarios are effectively improved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1721-1735
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• 2016

Power-efficient base station (BS) operation is one of the important issues in future green cellular networks. Previously well-known BS operation schemes, the cell zooming scheme and the cell wilting and blossoming scheme, require tight cooperation between cells in cellular networks. With the previous schemes, the non-cooperative BSs of a serving cell and neighboring cells could cause coverage holes between the cells, thereby seriously degrading the quality of service as well as the power saving efficiency of the cellular networks. In this paper, we propose a novel power-efficient BS operation scheme for green downlink heterogeneous cellular networks, in which the networks virtually adjust the coverage of a serving macrocell (SM) and neighboring macrocells (NMs) without adjusting the transmission power of the BSs when the SM is lightly loaded, and the networks turn off the BS of the SM when none of active users are associated with the SM. Simulation results show that our proposed scheme significantly improves the power saving efficiency without degrading the quality of service (e.g., system throughput) of a downlink heterogeneous LTE network and outperforms the previous schemes in terms of system throughput and power saving efficiency. In particular, with the proposed scheme, macrocells are able to operate independently without the cooperation of a SM and NMs for green heterogeneous cellular networks.

• Journal of Families and Better Life
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• v.31 no.4
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• pp.47-64
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• 2013

This study aimed to explore the social networks which married immigrant women have in Korea. Special attention was paid to factors such as individual, family, and migrant characteristics contributing to the different patterns of social networks. I drew upon the nationally representative data on 60,719 immigrant women married to Korean men from the '2009 Survey on Korean National Survey on Multicultural Families.' Results showed that the foreign wives tended to maintain a connection with our society through contact with their neighbors and participation in social gatherings. Findings also showed that the types of social networks by the number of trusted neighbors and meetings were diverse among the immigrant women. In addition, the factors differentiating the types were mostly associated with socioeconomic resources or Korean proficiency. More interestingly, the immigrant women's contacts with their family members in their homeland contributed to their maintenance of more active social networks. These results provided a useful outlook on the relationship between patterns of social networks and the characteristics of the married immigrant women, which eventually showed a heterogeneous nature among them. At the societal level, supportive systems for enriching immigrant women's social networks should be developed particularly in terms of not their dependency, but their potential contributions to our society.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.12
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• pp.223-231
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• 2021

The study aimed to investigate the impact of social networks safety (SNS) on the marketing information quality (MIQ) during the COVID-19 pandemic in Saudi Arabia. The study examines the statistical differences in social networks safety SNS and marketing information quality MIQ according to the demographics such as age, sex, income, and education. For this study purpose, information security and privacy are two components of social networks safety. The research materials are website resources, regular books, journals, and articles. The population includes all Saudi users of social networks. The figures show that active users of the social network reached 25 Million in 2020. The snowball method was used and sample size is 500 respondents and the questionnaire is the tool for the data collection. The Structural Equation Modelling SEM technique is used. Convergent Validity, Discriminate Validity, and Multicollinearity are the main assumptions of structural equation modeling SEM. The findings show the high positive impact of SNS networks safety on MIQ and the statistical differences in such variables refer to education. Finally, the study presents a set of future suggestions to enhance the safety of social networks in Saudi Arabia.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5218-5233
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• 2018

The coexisting wireless body area networks (WBAN) is a very challenging issue because of strong inter-networks interference, which seriously affects energy consumption and spectrum utilization ratio. In this paper, we study a power control strategy with nearest neighbor nodes distribution for coexisting WBAN based on stochastic geometry. Using homogeneous Poisson point processes (PPP) model, the relationship between the transmission power and the networks distribution is analytically derived to reduce interference to other devices. The goal of this paper is to increase the transmission success probability and throughput through power control strategy. In addition, we evaluate the area spectral efficiency simultaneously active WBAN in the same channel. Finally, extensive simulations are conducted to evaluate the power control algorithm.

• The Transactions of the Korea Information Processing Society
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• v.2 no.4
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• pp.581-591
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• 1995

An MIB is the heart of a network management system and it stores all information that is necessary for network management. To operate networks safely, it is essential to control accesses to managed objects. This paper provides three-level architecture of managers so as to perform network management more efficiently in large networks. Moreover, mandatory access control(MAC) policy and role-based access control policy are adopted to ensure the secure access to the MIB. These policies are modeled by using the active object-oriented data model, which makes easy to map these access control models into the active object-oriented database.

• Smart Structures and Systems
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• v.6 no.3
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• pp.335-347
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• 2010

Recent advances in hardware and instrumentation technology have allowed the possibility of deploying very large sensor arrays on structures. Exploiting the huge amount of data that can result in order to perform vibration-based structural health monitoring (SHM) is not a trivial task and requires research into a number of specific problems. In terms of pressing problems of interest, this paper discusses: the design and optimisation of appropriate sensor networks, efficient data reduction techniques, efficient and automated feature extraction methods, reliable methods to deal with environmental and operational variability, efficient training of machine learning techniques and multi-scale approaches for dealing with very local damage. The paper is a result of the ESF-S3T Eurocores project "Smart Sensing For Structural Health Monitoring" (S3HM) in which a consortium of academic partners from across Europe are attempting to address issues in the design of automated vibration-based SHM systems for structures.