• Journal of Korean Institute of Industrial Engineers
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• v.38 no.4
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• pp.285-288
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• 2012

The connectivity-based reliable multicast MAC protocol was proposed for IEEE 802.11 wireless LANs and the formulae for the lower bounds of the multicast downlink throughput and the uplink throughput of the connectivity-based reliable multicast MAC protocol were derived in our previous study. We provide the tighter throughput lower bounds of the connectivity-based reliable multicast MAC protocol than the lower bounds presented in our previous study.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.141-148
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• 2012

This paper presents a simple but efficient scheme incorporating a reputation-based approach and a cross-layer approach, called the SIM scheme, for maintaining reliable connectivity and high performance in ad-hoc wireless networks. The SIM scheme incorporates the following two things: an ad-hoc routing scheme with a reputation-based approach exploiting the game theory concept based on an evolutionarily stable strategy, and a cross-layer approach between the network layer and the transport layer employing a reputation-based approach.

• Journal of Korean Institute of Industrial Engineers
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• v.36 no.2
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• pp.94-100
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• 2010

The reliable multicast MAC (Medium Access Control) protocol is needed to guarantee the recipients' nonerroneous reception of the multicast data frames, which can be transmitted by the AP (Access Point) in infrastructure mode IEEE 802.11 wireless LANs. Enhancing the BMMM (Batch Mode Multicast MAC) protocol, in the literature, the connectivity-based reliable multicast MAC protocol was proposed to reduce the RAK (Request for ACKnowledgement) frame transmissions and enhance the multicast MAC performance. However, the number of necessary RAK frame transmissions increases as the number of multicast recipients increases. To alleviate the problem of the larger number of RAK frame transmissions with the larger number of multicast recipients, we propose the clustering algorithm for partitioning the recipients into a small number of clusters, so that the recipients are connected each other within the same clusters. Numerical examples are presented to show the reliable multicast MAC performance improvement by the clustering algorithm.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.1050-1057
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• 2016

SNS (Social network service) characteristics are perceived to simplify use. We carried out empirical studies on these parameters to observe the impact on the image of catering SNS online by word-of-mouth. The subjects of the study were as follows: 32.3% (392 persons) 19 years old, 67.7% (821 persons) over 19 years, 51.0% (619 persons) in their 20s, 22.1% (268 persons) in their 30s, 17.6% in their 50s, and 9.3% (112 persons) over 50 years. After verifying the hypothesis proposed that SNS characteristics perceived the ease of use, the significant factor identified in usability were connectivity Speed (${\beta}=0.213$), playfulness (${\beta}=0.246$), information (${\beta}=0.115$), and reciprocity (${\beta}=0.357$). Dual reciprocity had the most impact. It was observed that a longer impact of these significant factors improved the feel and fun of use. If SNS companies cater to, quick and easy, diverse, reliable and latest information, they can increase the ease of use, and availability, depending on the goals. Also, significant factors in the SNS features and online word of mouth was playfulness (${\beta}=0.312$), information (${\beta}=0.207$), reciprocity (${\beta}=0.066$) and perceived ease of use, and usefulness (${\beta}=0.293$), double playfulness had the maximum impact. These features provided more fun, reliable information, and could quickly deliver the latest information. The more the perceived usefulness, and ease of use, higher was the online word-of-mouth effect. SNS usage characteristics of connectivity Speed did not show any statistical significance in online word-of-mouth. Thus, catering businesses need to find ways to increase the ease of use, make the usefulness multifaceted, constantly checking the catering information on the SNS and ensuring to get the latest information is from diverse and reliable sources. This would increase the fun for the customer making the SNS to actively be utilized as a marketing tool.

• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.33-40
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• 2007

A multihomed enterprise or AS(Autonomous System) improves reliability and performance by acquiring its Internet connectivity from more than two ISP(Internet Service Provider). Multihoming protocol must allow a multihomed site whose connectivity through one of the ISPs fails to keep its Internet connectivity As one of mechanisms to do this, tunneling mechanism through Non-direct EBGP(Exterior Border Gateway Protocol) is defined. This mechanism makes connectivity to the Internet more reliable, but causes the problem that makes the communication route non-optimal. In this paper, we propose the route optimization mechanism using an extension header in the IPv6 multihoming environment.

• Steel and Composite Structures
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• v.19 no.2
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• pp.263-275
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• 2015

This study presents conceptual information of newly optimized shapes and connectivity of the so-called outrigger truss system for modern tall buildings that resists lateral loads induced by wind and earthquake forces. In practice, the outrigger truss consists of triangular or Vierendeel types to stiffen tall buildings, and the decision of outrigger design has been qualitatively achieved by only engineers' experience and intuition, including information of structural behaviors, although outrigger shapes and the member's connectivity absolutely affect building stiffness, the input of material, construction ability and so on. Therefore the design of outrigger trusses needs to be measured and determined according to scientific proofs like reliable optimal design tools. In this study, at first the shape and connectivity of an outrigger truss system are visually evaluated by using a conceptual design tool of the classical topology optimization method, and then are quantitatively investigated with respect to a structural safety as stiffness, an economical aspect as material quantity, and construction characteristics as the number of member connection. Numerical applications are studied to verify the effectiveness of the proposed design process to generate a new shape and connectivity of the outrigger for both static and dynamic responses.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3034-3055
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• 2014

Wireless Sensor Networks have extensively been utilized for ambient data collection from simple linear structures to dense tiered deployments. Issues related to optimal resource allocation still persist for simplistic deployments including linear and hierarchical networks. In this work, we investigate the case of dimensioning parameters for linear and tiered wireless sensor network deployments with notion of providing extended lifetime and reliable data delivery over extensive infrastructures. We provide a single consolidated reference for selection of intrinsic sensor network parameters like number of required nodes for deployment over specified area, network operational lifetime, data aggregation requirements, energy dissipation concerns and communication channel related signal reliability. The dimensioning parameters have been analyzed in a pipeline monitoring scenario using ZigBee communication platform and subsequently referred with analytical models to ensure the dimensioning process is reflected in real world deployment with minimum resource consumption and best network connectivity. Concerns over data aggregation and routing delay minimization have been discussed with possible solutions. Finally, we propose a node placement strategy based on a dynamic programming model for achieving reliable received signals and consistent application in structural health monitoring with multi hop and long distance connectivity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.914-923
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• 2015

UAS(Unmanned Aircraft System) has been used a lot in military applications but recently its usage is expanding to commercial applications due to its recent technical development and its market is expected to grow rapidly in the future. In hyper-connectivity society, especially UAS would play major role as an one of potential infrastructures for the architecture of the next 5G system. The ultimate goal is the successful integration of UAS in NAS(National Airspace System) relies heavily on ensuring reliable spectrum for the robust CNPC(Command and Non-Payload Communication) links as well as payload links for other various applications in the upcoming hyper-connectivity era. In this paper, we have focused on the analysis of the existing frequencies for UAS radio-control and the current issues for CNPC and payload frequencies, and proposed future efficient utilization policy for UAS in the hyper-connectivity society.

• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.215-219
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• 2005

Generally, the mobile nodes in MANET have the limited power capacity available for actual communications. Thus, the power management is very important for packet routing or forwarding. Although MTPR, MBCR and MMBCR are proposed to treat the problem of power consumption, there have been few researches resolving the link breakdown that is occurred by the power exhaustion during transmission. In this sense, the reliable scheme should be required to ensure the routing connectivity. In this paper, we propose three schemes to enforce the routing connectivity. If the signal strength is dropped below a signal threshold, the candidate route is previously selected to prepare the link breakdown. Also, on multi-channel, we propose the lifetime increment scheme of a node that it manage its available power to the needed power of a new link. The simulation results show the enforcement of the link connectivity and the performance improvements of the delay time through the effective connection management.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2218-2244
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• 2016

In this paper, we propose a hybrid routing scheme that utilizes location information to support reliable data transmission in mobile ad hoc networks. The proposed scheme determines and maintains routing path by considering the directionality and connectivity of nodes using grid zones and information on neighbor nodes. In addition, it generates alternative paths with consideration for node distance and reliability. To show the superiority of the proposed routing scheme, a performance evaluation was conducted using simulations. The performance evaluation results show that the proposed scheme offers faster and more reliable data transmission than the existing routing schemes, and the number of messages decreases by approximately 31% compared to the existing schemes on average.