• International Journal of Internet, Broadcasting and Communication
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• v.5 no.2
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• pp.18-22
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• 2013

Mobile IPv6 (MIPv6) is a host-based protocol supporting global mobility while Proxy Mobile IPv6 (PMIPv6) is a network-based protocol supporting localized mobility. This paper makes its focus on how to reduce the longer delay and extra cost arising from the combination of authentication, authorization and accounting (AAA) and PMIPv6 further. Firstly, a novel authentication scheme (Proxy-AAA) is proposed, which supports fast handover mode and forwarding mode between different local mobility anchors (LMAs). Secondly, a cost analysis model is established based on Proxy-AAA. From the theoretical analysis, it could be noted that the cost is affected by average arrival rate and residence time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.8-13
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• 2017

Compare with other communication system based RF technology, Optical Camera Communication (OCC) has limitation on data rate due to the low frame rate of camera. The limitation on data rate can be solved with multiple-input and multiple-output (MIMO) technology; and it is the final target of all researches on OCC. The MIMO topology can be implemented easily without breaking out the architecture of image sensor. For image sensor classification, there are two architectures have been developed: rolling shutter and global shutter. The operation of two techniques is different so the performance is also different. In this paper we analyze and evaluate the performance of the MIMO architecture for OCC.

• Journal of information and communication convergence engineering
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• v.10 no.3
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• pp.300-306
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• 2012

An image attention model and its application to image quality assessment are discussed in this paper. The attention model is based on rarity quantification, which is related to self-information to attract the attention in an image. It is relatively simpler than the others but results in taking more consideration of global contrasts between a pixel and the whole image. The visual attention model is used to develop a local distortion predictor, named color visual differences predictor (CVDP), in color images in order to effectively detect luminance and color distortions.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.129-134
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• 2021

Since the first semester of 2020, domestic and overseas universities mostly provided untact online classes and limitedly provided face-to-face classes due to COVID-19 in operating courses. The convergence subjects provided in undergraduate courses attach importance to contents-centered, design-based, hands-on education, and field experience. In the situation where online education was not revitalized, instructors in charge of convergence subjects had difficulty in developing online class materials, and students' satisfaction with the classes was not high. Especially, a problem was raised that students taking the convergence subjects that included practice had difficulty in communicating with the instructors. We would investigate the present condition of distance learning in domestic universities, which came suddenly due to the global pandemic of infectious disease and make suggestions for effective distance learning in the coming era of Metaverse by emphasizing the interaction and communication between instructors and learners through an analysis of distance learning of a convergence subject.

• International Journal of Computer Science & Network Security
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• v.22 no.1
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• pp.199-205
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• 2022

The main purpose of the study is to analyze the main aspects of the impact of information and communication technologies on the economic security system in the context of a pandemic situation. The new realities of the modern turbulent world require a new approach to the issues of ensuring economic security, in which information and communication technologies and information security are beginning to play an increasingly important role. As a result of a detailed analysis of the further functioning of all components of economic security in the context of the existence of the consequences of the COVID-19 pandemic.

• ETRI Journal
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• v.44 no.6
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• pp.915-924
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• 2022

In this paper, we present a two-stage scalable channel estimator (TSCE), a deep learning (DL)-based scalable, and robust channel estimator for wireless cellular networks, which is made up of two DL networks to efficiently support different resource allocation sizes and reference signal configurations. Both networks use the transformer, one of cutting-edge neural network architecture, as a backbone for accurate estimation. For computation-efficient global feature extractions, we propose using window and window averaging-based self-attentions. Our results show that TSCE learns wireless propagation channels correctly and outperforms both traditional estimators and baseline DL-based estimators. Additionally, scalability and robustness evaluations are performed, revealing that TSCE is more robust in various environments than the baseline DL-based estimators.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.136-148
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• 2024

In recent years, public attention to health and wellness issues has increased. The integration of smart fitness hardware and innovative technologies have made the development of smart fitness a trend. The number of fitness applications in the market has surged, and demand for an optimal experience is increasingly high. This study selects Sweatcoin, Home Workout, Six Pack in 30 Days, and Fitness Coach & Diet as research subjects from the top ten global mobile health and fitness apps in 2022 based on download rankings. The research is based on eight gamification elements: motivation, challenge, achievement, relationships, sharing, reward, level, and competition, identified through preliminary studies. We distributed a total of 166 questionnaires to users and collected 163 valid responses for data analysis. The Kano Model was used to study the desires of fitness enthusiasts using fitness apps. To reduce the limitations of the research results, the Better-Worse Method was employed for satisfaction index analysis. Based on the final analysis, we propose suggestions for improvement for the four fitness apps to better meet user needs and create a more attractive and efficient application experience.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.379-387
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• 2013

In large-scale wireless sensor networks, tremendous amount of dummy packets is usually accompanied by keeping location privacy of the communication source and destination against global eavesdropping. In our earlier work we designed a location privacy routing protocol, ELPR(End-node Location Privacy Routing) in which the generation of dummy packets at each idle time-slot while transferring data packets are restricted to only the nodes within certain areas of encompassing the source and destination, respectively. In this paper, it is given that ELPR provides various degrees of location privacy while PCM(Periodic Collection Method) allows the only fixed level. Simulation results show that as the number of nodes or data packets increases ELPR permits in terms of the number of generated packets more cost-effective location privacy than PCM.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.12-17
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• 2016

ICAO (International Civil Aviation Organization) recommends the introduction of SBAS (Satellite Based Augmentation System) in 2025, which provides GNSS (Global Navigation Satellite System) correction data and the ranging signal via GEO (geostationary earth orbit) satellites to GNSS users. In this paper, we present the basic design results of the satellite communication system RF link for the Korean SBAS systems, KASS (Korea Augmentation Satellite System) which is going on the development & implementation. KASS RF link was designed in consideration of both the C-band and Ku-band uplinks to meet the international standard requirements for the SBAS system, and identified the minimum EIRP and G/T performance of the KASS uplink station for each frequency band. These analysis results for the RF link design are expected to be used for an effective design of the subsystem specifications for KASS satellite communication system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.317-323
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• 1998

A synchronization is important element not only wire communication but also wireless communication. Especially, In SS(Spread Spectrum) communication method used GPS(Global Positioning System) synchronization is more important. A synchronous oscillator(SO) is a network which synchronizes, tracks, filter, amplifies and divides (if necessary) in a single process. Without an input signal, the SO is a free-running oscillator, oscillating at a frequency $w_0$, but phase changes $180^{\circ}$ within tracking range of SO. Therefore CPSO was used for this problem. The coherent phase synchronous oscillator(CPSO) is created by adding two external loops to the SO and has a wider tracking bandwidth and a zero-offset phase response (coherent) while maintaining the SO properties of high signal-to-rejection and fast frequency acquisition times. Therefore phase between input signal and output signal is synchronized. In this paper, GPS data recovery circuit has applied CPSO using front reference characters and has certified an excellent data recovery capability.