• Journal of Korea Multimedia Society
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• v.17 no.4
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• pp.433-440
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• 2014

Wireless communication offers the flexibility to the node movement at the spatial dimension more than the wire communication not only in IP architecture but also in Content-Centric Networking. Although it gives such advantage, the intra-domain movement of a node especially the data source node affects the communication to the access point node which in the end affects the acceptance ratio of the client node that requests the data packets from the data source node. In this paper, we use time-division access method to maintain the acceptance ratio of the client node as the effect of the intra-domain data source node movement in Content-Centric Networking. The simulation result shows that the acceptance ratio of the client node can be maintained using the time-division access method as long as the interval access time is less than the coherence time.

• Journal of Information Processing Systems
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• v.13 no.3
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• pp.630-642
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• 2017

In this paper, we propose the opportunistic non-orthogonal multiple access (NOMA)-based cooperative relaying system (CRS) with channel state information (CSI) available at the source, where CSI for the source-to-destination and source-to-relay links is used for opportunistic transmission. Using the CSI, for opportunistic transmission, the source instantaneously chooses between the direct transmission and the cooperative NOMA transmission. We provide an asymptotic expression for the average achievable rate of the opportunistic NOMA-based CRS under Rayleigh fading channels. We verify the asymptotic analysis through Monte Carlo simulations, and compare the average achievable rates of the opportunistic NOMA-based CRS and the conventional one for various channel powers and power allocation coefficients used for NOMA.

• The Journal of Korean Society for School & Community Health Education
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• v.11 no.1
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• pp.67-78
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• 2010

Background & Objectives: Current trend is that funding agencies require investigators to share their data with others. However, there is limited guidance how to access and utilize the shared data. We sought to determine what common data sharing practices in U.S.A. are, what data-related to adolescent health are freely available, and how we deal with the large dataset adopting the complex study design. Methods: The study included only research data-related to adolescent health which was collected in USA and unlimitedly accessible through the internet. Only the raw data, not aggregated, was considered for the study. Major keywords for web search were "adolescent", "children", "health", and "school". Results: Current approaches for public health data sharing lacked of common standards and varied largely due to the data's complex nature, large size, local expertise and internal procedures. Some common data sharing practices are unlimited access, formal screened access, restricted access, and informal exclusive access. The Inter-University Consortium for Political and Social Research and the Center for Disease Control and Prevention were the best data depository. "Data on the net" was search engine for the website providing data freely available. Six datasets related to adolescent health freely available were identified. The importance and methods of incorporating complex research design into analysis was discussed. Conclusion: There have been various attempts to standardize process for open access and open data using the information technology concept. However, it may not be easy for researchers to adapt themselves to this high technology. Therefore, guidance provided by this study may help researchers enhance the accessibility to and the utilization of the open source data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.445-446
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• 2021

Union file system is a technology that can be used as a single file system by integrating various files and directories. It has the advantage of maintaining the source file/directory used for integration, so it is used in many applications like container platform. When using the union file system, the user accesses the write-able layer, to which the security technology provided by the operating system can be applied. However, there is a disadvantage in that it is difficult to apply a separate security technology to the source file and directory used to create the union file system. In this study, we intend to propose an access control mechanism to deny security threats to source file/directory that may occur when using the union file system. In order to verify the effectiveness of the access control mechanism, it was confirmed that the access control mechanism proposed in this study can protect the source file/directory while maintaining the advantages of the union file system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.111-120
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• 2006

In this paper, a node architecture of WDM metro network for connecting broadband access networks to converge wire/wireless networks. In consideration of the proposed node architecture and network requirements we proposed and evaluated medium access control protocols. We review WDM related technologies of sub-carrier multiplexing and optical components in order to resolve the bottleneck between optical backbone networks md access networks, and a access node architecture sharing common wavelength is introduced. Source-stripping (SS) MAC protocol Is evaluated under the proposed functional node architecture. DS+IS (Destination-Stripping and Source-Stripping) and DS+IS (Destination-Stripping and Intermediate-Stripping) MAC protocols are described to increase the slot-reuse factor which is low on SS MAC protocol. The key function of new MAC protocols regards the optical switch module of proposed node architecture and helps intermediate or source access nodes for dropping slots to destinations of different wavelength group. Thus, slot-reuse factor increases as the MAC protocols reduce the unnecessary ring-rotation of transferred slots. We use a numerical analysis to expect bandwidth efficiency and maximum throughput by slot-reuse factor Throughput network simulation, the verification of throughput, queuing delay, and transmission fairness are compared among MAC protocols.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.8-14
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• 2020

Recently, there was an increasing demand for an integrated access control system which is capable of user recognition, door control, and facility operations control for smart buildings automation. The market available door lock access control solutions need to be improved from the current level security of door locks operations where security is compromised when a password or digital keys are exposed to the strangers. At present, the access control system solution providers focusing on developing an automatic access control system using (RF) based technologies like bluetooth, WiFi, etc. All the existing automatic door access control technologies required an additional hardware interface and always vulnerable security threads. This paper proposes the user identification and authentication solution for automatic door lock control operations using camera based visible light communication (VLC) technology. This proposed approach use the cameras installed in building facility, user smart devices and IoT open source controller based LED light sensors installed in buildings infrastructure. The building facility installed IoT LED light sensors transmit the authorized user and facility information color grid code and the smart device camera decode the user informations and verify with stored user information then indicate the authentication status to the user and send authentication acknowledgement to facility door lock integrated camera to control the door lock operations. The camera based VLC receiver uses the artificial intelligence (AI) methods to decode VLC data to improve the VLC performance. This paper implements the testbed model using IoT open-source based LED light sensor with CCTV camera and user smartphone devices. The experiment results are verified with custom made convolutional neural network (CNN) based AI techniques for VLC deciding method on smart devices and PC based CCTV monitoring solutions. The archived experiment results confirm that proposed door access control solution is effective and robust for automatic door access control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.589-597
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• 2007

In this paper, a WDM metro ring consisting of access nodes with $FT-FR^n$ (Fixed Transmitter - n Fixed Receivers) is considered. A trade-off exists between node throughput and transmission fairness because the access nodes share wavelength channels. In order to eliminate the transmission unfairness and to increase throughput, the p-persistent medium access control (MAC) protocol is proposed: each node uses an empty optical slot to transmit a packet and make it available with the extraction of a transferred packet at the source access node, called source-stripping. The local empty slot can be used to transfer a head-of-line packet in the local buffer with probability p or it is used for the next downstream nodes with 1-p. The proposed MAC protocol provides better node throughput than the non-persistent protocol and exhibits better fairness index than the 1-persistent protocol in WDM ring networks. In addition, numerical analysis shows that the proposed MAC protocol maximizes the node throughput under uniform traffic conditions. For more detailed results, we use the network simulation under Poisson and self-similar traffic. Furthermore, unpredictable traffic constructed by the combination of the former and the latter is also considered. The reasonable probability of the p-persistent protocol for a given architecture can be determined through simulation.

• 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.

• International Journal of Knowledge Content Development & Technology
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• v.6 no.1
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• pp.69-84
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• 2016

The paper investigates open access (OA) self archiving policies of different Open Access Repositories (OARs) of COAPI (Coalition of Open Access Policy Institutions) founder members as reported in June 2011 (i.e. a total of 22 members against a total of 46 COPAI members as reported by Open Biomed (http://openbiomed.info/2011/08/coapi-cats/). The paper consulted three databases (OpenDOAR, ROAR and ROARMAP) in order to evaluate twenty-two (22) COAPI-members OARs self archiving policy documentations and highlights of some progress on issues so far. After analyzing policy documentations, key findings have been highlighted and common practices have been suggested in line with global recommendations and best practice guidelines at national and international levels for strengthening national research systems. The paper has implications for administrators, funding agencies, policy makers and professional librarians in devising institute specific self archiving policies for their own organization.

• Journal of Advanced Navigation Technology
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• v.12 no.5
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• pp.451-463
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• 2008

There are management and security of software source code equivalent to 10 assembly lines of important infrastructure in the early stage of information society directly. A support technology and framework to protect software source code are so poor state In this paper, the proposed model that is support protection and access control between software source code as object and subject that is not authenticated safely was named CRYPTEX model. And we propose active business model to provide delegate, mobile, and security/access control function for passive software source code in document state using CRYPTEX.