• Journal of Communications and Networks
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• v.11 no.3
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• pp.287-296
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• 2009

Although asymptotic bounds of wireless network capacity have been heavily pursued, the answers to the following questions are still critical for network planning, protocol and architecture design: Given a three-dimensional (3D) network space with the number of active users randomly located in the space and using the wireless communication technology, what are the expected per-flow throughput, network capacity, and network transport capacity? In addition, how can the protocol parameters be tuned to enhance network performance? In this paper, we focus on the ultra wideband (UWB) based wireless personal area networks (WPANs) and provide answers to these questions, considering the salient features of UWB communications, i.e., low transmission/interference power level, accurate ranging capability, etc. Specifically, we demonstrate how to explore the spatial multiplexing gain of UWB networks by allowing appropriate concurrent transmissions. Given 3D space and the number of active users, we derive the expected number of concurrent transmissions, network capacity and transport capacity of the UWB network. The results reveal the main factors affecting network (transport) capacity, and how to determine the best protocol parameters, e.g., exclusive region size, in order to maximize the capacity. Extensive simulation results are given to validate the analytical results.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.1
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• pp.28-37
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• 1993

The future Personal Communication Service(PCS) is the total personal information communication service to satisfy the importance of information in a highly information - oriented society. Compared with the conventional communication method, it is necessary to provide considerable intelligence to the commu- nication network in order to implement the PCS which guarantees the mobility of each individual. Consequen- tly, the PCS needs a fast large database system which stores the information of each individual. To achieve this goal, this paper presents the parallel implementation of deductive database systems as a main - memory database system.

• Journal of Internet Computing and Services
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• v.15 no.2
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• pp.73-85
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• 2014

This study analyzed the profile of a Facebook account to examine how personal information is revealed and what kinds of factors influence personal information revelation. Categories of user's profile on Facebook were analyzed and two dimensions were developed; the degree that how much personal information is revealed and the network limits that personal information is accessed. Main variables to determine personal information revelation are Facebook privacy concern and uses for social relationships along with gender, the duration of Facebook use, and average time of use. Data were collected from college students. Factor analysis produced two factors of Facebook privacy concern, Facebook privacy concern with users and Facebook privacy concern with the Facebook system. Regression analyses were performed to identify significant determinants of the degree of information revelation and the network limits of personal information. The results found out that the degree of personal information revelation is explained by gender, the duration of use, and use for social relationships while the network limit is explained by the duration of use and Facebook privacy concern with users. Worthy of notice is that use for social relationships and Facebook privacy concern with the Facebook system offset each other. The implications of the results are discussed. Additionally and finally the categories of profiles are graphically re-grouped to show how personal information revelation is associated with social relationship generation and maintenance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7A
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• pp.669-677
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• 2011

Superframe in IEEE 802.15.4 Standard is subdivided into an active period and an inactive period to reduce energy consumption. But communication nodes use same data transmission range in an active period, thus communication nodes spend a lot of energy to send data another nodes. In this paper, we proposed reduce energy consumption algorithm that nodes use different transmission power. Cordinator split transmission area into four group and transmit becon message to nodes. Nodes adjust transmission power according to becon message and wates lowe energy than normal nodes. We proposed energy-efficient cross layer protocol that have different PAN (Personal Area Network) by four range group.

• Journal of Communications and Networks
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• v.16 no.1
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• pp.36-44
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• 2014

Exploiting the energy-delay tradeoff for energy saving is critical for developing green wireless communication systems. In this paper, we investigate the delay-constrained energy-efficient packet transmission. We aim to minimize the energy consumption of multiple randomly arrived packets in an additive white Gaussian noise channel subject to individual packet delay constraints, by taking into account the practical on-off circuit power consumption at the transmitter. First, we consider the offline case, by assuming that the full packet arrival information is known a priori at the transmitter, and formulate the energy minimization problem as a non-convex optimization problem. By exploiting the specific problem structure, we propose an efficient scheduling algorithm to obtain the globally optimal solution. It is shown that the optimal solution consists of two types of scheduling intervals, namely "selected-off" and "always-on" intervals, which correspond to bits-per-joule energy efficiency maximization and "lazy scheduling" rate allocation, respectively. Next, we consider the practical online case where only causal packet arrival information is available. Inspired by the optimal offline solution, we propose a new online scheme. It is shown by simulations that the proposed online scheme has a comparable performance with the optimal offline one and outperforms the design without considering on-off circuit power as well as the other heuristically designed online schemes.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.65-72
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• 2015

Although the development of digital technology and network has brought great convenience in modern lives, amongst the aggravated complexity in the contemporary society, modern minds who have failed to create genuine relationships undergo a sense of alienation and solitude that may appear as a type of social pathology called cellular-phone addiction. Also, while the emergence of the information age seemingly brings about benefits including diverse acquisition regarding knowledge and broader communication, underneath exists side effects involving leakage of private information. Especially, being excessively addicted to relationship network may induce one to become insensitive towards leakage of private information without recognizing, and thereby instigating yet another social problem. Media art is very practical in terms of suggesting a critical perspective concerning social phenomena and elevating them into a work of art by rendering them artistically. Particularly, when social problems of the modern days are expressed through digital technology, media art provides the audience with a foundation that will enable them to sympathize without hostility. This dissertation calls attention to the contemporary problems regarding cellular-phone addiction and possible hazards of information leakage based on media art, while at the same time proposing the production process of a media art work that attempts to raise awareness and sympathy on such social issues.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2292-2300
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• 2015

Car rear-view camera system supplies services for safe driving and easy parking by showing the rear-view of the vehicle through a monitor when reversing the car. In this paper we researched implementation methods and technology of a Car Rear-view Camera System based on the Binary CDMA technology-new technology of wireless personal area network developed by Korea - that makes free installation without wired cables restriction and reduces installation costs. Through this research we manufactured a prototype system, and researched the implementation of camera input and monitor output modules, Binary CDMA wireless communication and application programs for wireless video transmitter and relay server.

• The Transactions of the Korea Information Processing Society
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• v.1 no.4
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• pp.502-510
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• 1994

CDMA technique has been largely focused for Wireless Data Communication and Personal Communication Network. ALOHA protocol also has been proven to be effective for Packet Radio Radio Network regardless of low throughput due to channel collisions. In this paper, we evaluate the performance of MS-CDMA-ALOHA (Mini-Slotted-CDMA-ALOHA) system, by analytic and simulation method. The superiority of the MS-CDMA-ALOHA system over conventional Slotted ALOHA and Slotted-CDMA-ALOHA systems are clearly demonstrated for throughput, delay and stability performances.

• Journal of Information Technology Services
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• v.15 no.4
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• pp.41-62
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• 2016

In Internet of Things (IoT) era, more diverse types of information are collected and the environment of information usage, distribution, and processing is changing. Recently, there have been a growing number of cases involving breach and infringement of personal information in IoT services, for examples, including data breach incidents of Web cam service or drone and hacking cases of smart connected car or individual monitoring service. With the evolution of IoT, concerns on personal information protection has become a crucial issue and thus the risk analysis and management method of personal information should be systematically prepared. This study shows risk factors in IoT regarding possible breach of personal information and infringement of privacy. We propose "a risk analysis framework of protecting personal information in IoT environments" consisting of asset (personal information-type and sensitivity) subject to risk, threats of infringement (device, network, and server points), and social impact caused from the privacy incident. To verify this proposed framework, we conducted risk analysis of IoT services (smart communication device, connected car, smart healthcare, smart home, and smart infra) using this framework. Based on the analysis results, we identified the level of risk to personal information in IoT services and suggested measures to protect personal information and appropriately use it.

• International journal of advanced smart convergence
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• v.1 no.2
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• pp.34-38
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• 2012

The recent increase in use of the IEEE 802.15.4 standard for wireless connectivity in personal area networks makes of it an important technology for low-cost low-power wireless personal area networks. Studies showed that voice communications over IEEE 802.15.4 networks is feasible by Guaranteed Time Slot (GTS) allocation; but there are some constraints to accommodate voice transmission beyond two hops due to the excessive transmission delay. In this paper, we propose a GTS allocation scheme for bidirectional voice traffic in IEEE 802.15.4 multihop networks with the goal of achieving fairness and optimization of resource allocation. The proposed scheme uses a greedy algorithm to allocate GTSs to devices for successful completion of voice transmission with efficient use of bandwidth while considering closest devices with another factor for starvation avoidance. We analyze and validate the proposed scheme in terms of fairness and resource optimization through numeral analysis.