• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.423-432
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• 2011

In a warehouse, because there exist frequent changes of stock status and the quality of some contents are influenced by the environment such as temperature, fast and accurate management of the warehouse's environment is very important for Warehouse Management Systems (WMS). However, due to the absence of a unified standard for the communication protocol between RFID nodes, the connection between RFID nodes can be broken in case of movement of a RFID reader to a region with a different protocol. Moreover, centralized MAC schemes for RFID communications in previous studies have severe problems. For an example, if a cluster header disappears from the cluster due to the cluster header's movement or bad channel conditions, the RFID member nodes of the cluster waste lots of time and energy to re-elect a new cluster header. Therefore, in this paper, we propose a WiMedia Distributed MAC (D-MAC) scheme for RFID communications and its cooperative relay transmission scheme for WMS applications Simulation results show performance improvement at the RFID node by using the proposed cooperative relay transmission scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2553-2562
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• 2013

It is difficult for TCP congestion control algorithm to ensure the bandwidth and delay bound required for media streaming services in broadband wireless network environments. In this paper, we propose the COIN TCP (COncave INcrease TCP) scheme for providing a high-quality media streaming services. The COIN TCP concavely increases the congestion window size by adjusting the increment rate of congestion window, that is inversely proportional to the amount of data accumulated in the router queue. As a result, our scheme can quickly occupy the available bandwidth and prevent the heavy congestion. It also improves the link utilization by adjusting the decrement rate of congestion window according to the packet loss rate with the random loss. Through the simulation results, we prove that our scheme improves the total throughput in broadband wireless network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.595-601
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• 2013

This paper presents an optimized design of a millimeter-wave on-chip dipole antenna using CMOS process. The serious flaw of the antenna using CMOS process is low radiation efficiency because of high permittivity and conductivity. To overcome the weakness, we need to widen radiation area in air and optimize distance between an antenna and a reflector. The radiation efficiency and bandwidth of the designed antenna are respectively 16.5 % and 22.3 % at 80 GHz. Systematic methods are attempt to analyze an effect on the antenna radiation efficiency. To widen radiation area in air, substrate cut angle and distance between the antenna and chip edge are adjusted. In addition, to optimize distance between an antenna and reflector, substrate thickness and distance between the antenna and a circuit ground plane are adjusted.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8C
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• pp.806-813
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• 2009

This paper presents a modem chip design for high-speed wireless communications. Among the high-speed communication technologies, we design the UWB (Ultra-Wideband) modem SoC (System-on-Chip) Chip based on a MB-OFDM scheme which uses wide frequency band and gives low frequency interference to other communication services. The baseband system of the modem SoC chip is designed according to the standard document published by WiMedia. The SoC chip consists of FFT/IFFT (Fast Fourier Transform/Inverse Fast Fourier Transform), transmitter, receiver, symbol synchronizer, frequency offset estimator, Viterbi decoder, and other receiving parts. The chip is designed using 90nm CMOS (Complementary Metal-Oxide-Semiconductor) procedure. The chip size is about 5mm x 5mm and was fab-out in July 20th, 2009.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.159-170
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• 2008

The ubiquitous network revolution is beginning with the onset of digital convergence, whereby computers, horne appliances, and communications and broadcast media are being unified into digital media with the founding of the information super high speed. This technical advancement is creating a new culture and a new space and accelerating society's transition to the new and unique social paradigm of a 'ubiquitous society'. In particular, studies on ubiquitous communications are well underway. Lately, the focus has been on the Bluetooth technology due to its applicability in various environments. Applying Bluetooth connectivity to new environments such as ubiquitous or sensor networks requires finding new ways of using it. Thus, the scalable Bluetooth piconet scheme with independent slave device is proposed. It follows from work by Sea et al. But extended scatternet is not considered is Kiisc05 paper. Therefore, we propose secure bridge connection scheme for scalable Bluetooth scatternet.

• Informatization Policy
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• v.19 no.4
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• pp.3-26
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• 2012

The purpose of this study is to provide a systematical view point of SNS research published by scholarly journals in communications vis a meta-analysis. A total of 72 articles dealing with SNS issues from 2006 to 2012 were analysed by research theme, related sub-theme, methodology, theoretic rationale, targeted media, and characteristics. Effect research get the largest portion and then user research in terms of a developmental model of media research agenda. A major methodological trend is an online survey and theoretical background is Uses and Gratification. Twitter is the most popular medium researched and SNS is mainly characterized as information provision and seeking as well as relationship forming.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.524-532
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• 2012

In this paper, we present the performance evaluation of the reliable cooperative media access control (RCO-MAC) protocol, which has been proposed in [1] by us in order to enhance system throughput in bad wireless channel environments. The performance of this protocol is evaluated with computer simulation as well as mathematical analysis in this paper. The system throughput, two types of average delays, average channel access delay, and average system delay, which includes the queuing delay in the buffer, are used as performance metrics. In addition, two different traffic models are used for performance evaluation: The saturated traffic model for computing system throughput and average channel access delay, and the exponential data generation model for calculating average system delay. The numerical results show that the RCO-MAC protocol proposed by us provides over 20% more system throughput than the relay distributed coordination function (rDCF) scheme. The numerical results show that the RCO-MAC protocol provides a slightly higher average channel access delay over a greater number of source nodes than the rDCF. This is because a greater number of source nodes provide more opportunities for cooperative request to send (CRTS) frame collisions and because the value of the related retransmission timer is greater in the RCO-MAC protocol than in the rDCF protocol. The numerical results also confirm that the RCO-MAC protocol provides better average system delay over the whole gamut of the number of source nodes than the rDCF protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.430-441
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• 2006

As the various A/V devices and home networks are delivered to users, home networks are changing to an entertainment network. It is expected that the required network bandwidth and the amount of usage of media content in home entertainment networks will be increased. Although the access networks and home networks becoming a high speed network, there remains the problems for QoS-guaranteed media content transfer in home networks. Also, in the home network, there can be network traffic caused by applications like video conferencing, video telephone, and VoIP(voice over IP) as well as inner network traffic of home network. Since media content transfer requires the real-time delivery, it is very important and basic requirement that is to transfer media content to A/V device user wants while keeping the media quality. Even though there are many middleware protocol for home networking, they provide basic device discovery and control or simple functions for QoS-guaranteed media content transfer that are not enough to provide QoS-guaranteed media transfer service that user wants. Thus, in this paper, we propose the technique based on UPnP(universal plug and play) protocol for QoS-guaranteed media content transfer in the home network. The proposed technique is compatible with UPnP and can be used with UPnP as additional functions. In this paper, we utilize VideoLAN application to verify the proposed technique. We add the additional modules that support the proposed technique's function to VideoLAN and we verify the its functions through various test scenarios.

• The KIPS Transactions:PartD
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• v.18D no.4
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• pp.275-286
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• 2011

The purpose of this study is to find the beneficial plan for business success by the advantage of social media service in the business organization. There is few research for applying social media on a variety of fields in business organization although many companies are trying to find the way for its application. Hence, this study identifies the possibility for the utilization of social media services, and it also finds the plan for their effective application. The social relationship is created by increasing communications between users of social media service. The research model is established on the basis of the hypothesis that the social relationship affects knowledge share, pursuit of ego, social participation, amusement. To maximize the impact of results, the research was conducted on the basis of the target on two groups including the business men and non-business men who use social media services. As results of the research, the business men tend to appeal their impression based on sharing knowledge with anonymous people. Also, it is necessary to make a social participation to a management participation, and to utilize the social media in the organization by including amusement to its function. This research is expected to have significant implication to companies which wants to apply social media services in the future.

• Journal of Broadcast Engineering
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• v.22 no.4
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• pp.429-437
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• 2017

2D-to-3D conversion technology has been studied over past decades and integrated to commercial 3D displays and 3DTVs. Generally, depth cues extracted from a static image is used for generating a depth map followed by DIBR (Depth Image Based Rendering) for producing a stereoscopic image. Further, motion is also an important cue for depth estimation and is estimated by block-based motion estimation, optical flow and so forth. This papers proposes a new method for motion depth generation using Motion History Image (MHI) and evaluates the feasiblity of the MHI utilization. In the experiments, the proposed method was performed on eight video clips with a variety of motion classes. From a qualitative test on motion depth maps as well as the comparison of the processing time, we validated the feasibility of the proposed method.