• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2597-2615
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• 2013

This paper proposes a dynamic downlink load control scheme that jointly employs dynamic load threshold management and virtual coverage management schemes to reduce the degree of performance degradation due to traffic overload in two-tier femtocell networks. With the proposed scheme, the downlink load in a serving macrocell is controlled with a load threshold which is adjusted dynamically depending on the varying downlink load conditions of neighboring macrocells. In addition, traffic overloading is alleviated by virtually adjusting the coverage of the overloaded serving macrocell, based on the adjusted load threshold of the serving macrocell. Simulation results show that the proposed scheme improves the performance of two-tier femtocell networks in terms of the outage probability and sum throughput. This improvement is significantly increased with appropriate values of load thresholds and with an intermediate-level adjustment of the virtual coverage area (i.e., handover hysteresis margin: HOM). Furthermore, the proposed scheme outperforms both a previously proposed load control scheme with a static load threshold and the LTE system without a HOM adjustment.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.601-602
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• 2011

In wireless sensor networks, coverage problem is a fundamental issue that has attracted considerable attention in recent years. Most node scheduling patterns utilize the adjustable range of sensor to minimize the sensing energy consumption. However, a large source of consumption of communication energy of sensor is not strictly taken into account. In this paper, we introduce an energy-efficient pattern that is used to minimize the communication energy consumption of a sensor network. Calculations and extensive simulation are conducted to evaluate the efficiency of the new pattern comparing to existing ones.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.326-354
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• 2014

In this paper, a new green clustering algorithm is proposed to be as a first approach in the framework of an energy efficient strategy for centralized enterprise high-density WLANs. Traditionally, in order to maintain the network coverage, all the APs within the WLAN have to be powered-on. Nevertheless, the new algorithm can power-off a large proportion of APs while the coverage is maintained as its always-on counterpart. The two main components of the new approach are the faster procedure based on K-means and the more accurate procedure based on Evolutionary Algorithm (EA), respectively. The two procedures are processes in parallel for different designed requirements and there is information interaction in between. In order to implement the new algorithm, EA is applied to handle the optimization of multiple objectives. Moreover, we adapt the method for selection and recombination, and then introduce a new operator for mutation. This paper also presents simulations in scenarios modeled with ray-tracing method and FDTD technique, and the results show that about 67% to 90% of energy consumption can be saved while it is able to maintain the original network coverage during periods when few users are online or the traffic load is low.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.4
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• pp.922-937
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• 2024

Maritime activities are on the rise, there is a growing demand for high-quality communication services that can cover larger areas. However, the transmission of high data rates to maritime users is challenging due to path loss from land base stations, which limits the transmission power. To overcome this challenge, researchers have been exploring the use of buoys in a marine environment as relays for communication technology. This paper proposes a simulation-based approach to investigate the impact of various beamwidths on communication performance when using a buoy as a relay. The objective is to determine the optimal beamwidth that yields the highest data rate for the target location. The approach is based on an offshore wave model where the direction of the buoy changes according to the height of the wave. The study investigates the performance of the relay in the downlink situation using receive beamforming, and the capacity at the user in the three-hop situation is verified using an amplify-and-forward (AF) relay that uses transmit beamforming to the user. The simulation results suggest that the beamwidth of the relay should be adjusted according to the wave conditions to optimize the data rate and relay position that satisfies a data rate superior to the direct path to the target position. Using a buoy as a relay can be a promising solution for enhancing maritime communications, and the simulation-based approach proposed in this paper can provide insights into how to optimize beamwidth for effective communication system design and implementation. In conclusion, the study results suggest that the use of buoys as relays for maritime communication is a feasible solution for expanding coverage and enhancing communication quality. The proposed simulation-based approach provides a useful tool for identifying relay beamwidths for achieving higher data rates in different wave conditions. These findings have significant implications for the design and deployment of communication systems in maritime environments.

• Korean journal of communication and information
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• v.19
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• pp.213-238
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• 2002

Ie is popular belief among the authorities concerned and their apologists that media coverage of terrorism promotes terrorism and is used as publicity by terrorists. Generally speaking, however, in reporting terrorism, the media become not terrorists' but state's means of publicity, and condemn terrorism, while rationalizing state's violence against terrorism. Terrorists may be successful in attracting public attention at the initial stage of terrorism, but usually fail in publicizing their cause. This fact notwithstanding, the authorities concerned and their apologists maintain thar media coverage of terrorism should be controlled, because it works as publicity for terrorists. Now it can be said that there is an intention to control the media when it is asserted that media coverage of terrorism works as publicity for terrorists. To present these arguments, this article discusses the news values and publicity aspect of terrorism, reviews some problems of and misunderstanding about media coverage of terrorism, and for illustrations, look into the American media's coverage of the 9-11 terrorism against the U. S. and "war on terror". that is, state terrorism taken as a countermeasure to it by the U. S.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3621-3640
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• 2016

In the process of k-coverage of the target node, there will be a lot of data redundancy forcing the phenomenon of congestion which reduces network communication capability and coverage, and accelerates network energy consumption. Therefore, this paper proposes a novel energy balanced k-coverage control algorithm based on probability model (EBKCCA). The algorithm constructs the coverage network model by using the positional relationship between the nodes. By analyzing the network model, the coverage expected value of nodes and the minimum number of nodes in the monitoring area are given. In terms of energy consumption, this paper gives the proportion of energy conversion functions between working nodes and neighboring nodes. By using the function proportional to schedule low energy nodes, we achieve the energy balance of the whole network and optimizing network resources. The last simulation experiments indicate that this algorithm can not only improve the quality of network coverage, but also completely inhibit the rapid energy consumption of node, and extend the network lifetime.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.5014-5034
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• 2016

This paper discusses how to effectively guarantee the coverage and connectivity quality of wireless sensor networks when joint perception model is used for the nodes whose communication ranges are multi-level adjustable in the absence of position information. A Connect Coverage Algorithm Based on Joint Sensing model (CCAJS) is proposed, with which least working nodes are chosen based on probability model ensuring the coverage quality of the network. The algorithm can balance the position distribution of selected working nodes as far as possible, as well as reduce the overall energy consumption of the whole network. The simulation results show that, less working nodes are needed to ensure the coverage quality of networks using joint perception model than using the binary perception model. CCAJS can not only satisfy expected coverage quality and connectivity, but also decrease the energy consumption, thereby prolonging the network lifetime.

• Korean journal of communication and information
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• v.29
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• pp.7-41
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• 2005

This article examines the influences of Journalist gender and gender ratio in the newsroom on news coverage of women among three national newspapers in Korea. Results reveal that female reporters describe women newsmakers in greater length, of more diversity in occupations, and of more positive pattern than their colleagues, male reporters do. The newspaper employing more female reporters also covers female newsmakers with less personal information, of more diversity in occupations, and of more positive pattern. It is suggested that increase of female reporters in the newsroom induce male reporters to cover women newsmakers toward a pro-female attitude. Lastly, the relation of the gender ratio variation in the news organization and news coverage of women is discussed.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.605-606
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• 2012

In this paper, we consider the problem of scheduling sensor activity to prolong the network lifetime while guaranteeing both discrete target coverage and connectivity among all the active sensors and the sink, called connected target coverage (CTC) problem. We proposed a distributed scheme called Distributed Lifetime-Maximizing Scheme (DLMS) to solve the CTC problem. Our proposed scheme significantly reduces the cost of the construction of the connected cover graphs in comparison with the some conventional schemes. In addition, the energy consumption is more balanced so that the network lifetime will be increased. Our simulation results show that DLMS scheme performs much better than the conventional schemes in terms of the network lifetime.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.395-402
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• 2023

The implementation of a hybrid network utilizing Power Line Communication (PLC) and Wi-Fi technologies has been demonstrated to improve signal strength and coverage in areas with poor connectivity due to internet shadow areas. In this study we strategically positioned Wi-Fi relays and utilized the capabilities of PLC technology to significantly improve signal strength and coverage in areas with poor connectivity. We also analyzed the effects of metallic obstacles on Wi-Fi signal propagation and proposed a solution to strengthen the signal enough to pass through them. Our experiment demonstrated the feasibility and potential of using this hybrid network in industrial scenarios for real-time data transmission. Overall, the results suggest that the use of PLC and Wi-Fi hybrid networks can be a cost-effective and efficient solution for overcoming internet connectivity challenges and has the potential to provide high-speed internet access to areas with unreliable signals.