• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.16-22
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• 2023

Enhanced radio access technologies (RAT) are deployed in Next Generation Convergence Networks by the service providers so as to satisfy the basic requirements of end-users for e.g. QoS. Whenever the available resources are being shared simultaneously and dynamically by multiple users or distribution of allocated channels randomly, the deficiency of spectral resources and dynamic behavior of Network traffic in real time Networking, we may have problem. In order to evaluate the performance of our proposed algorithm, computer simulation has been performed on NS-2 simulator and a comparison with the existing algorithms has been made.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.529-540
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• 2015

The NGN should support an ubiquitous environment in which users can use multiple devices. Especially, services should be provided to users in a seamless manner across multiple devices which are dynamically found in users' vicinity. Therefore, supporting service continuity is essential in the NGN. Currently the IMS, which is a session control layer for the NGN, deals with session control procedures in detail for service continuity. However, the IMS provides limited methods how users can find target terminals for transferring the session. The target terminals tend to be located near in user's physical location, and could be shared among different users. For providing better service experience in the NGN, The NGN needs to encompass methods to enable for users to use the dynamically-found terminals in users' vicinity seamlessly. In this paper, we introduce a novel registration method based on virtual ISIM by which the target terminals in user's vicinity can register themselves to the IMS, and also we discuss how service continuity is supported.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.224-231
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• 2008

EPONs are a low cost, high speed solution to the bottleneck problem of broadband access networks. To support point-to-point and shared LAN emulation, EPONs use the multi-point control protocol (MPCP), which uses logical link identification (LLID) for frame tagging and filtering between the OLT and ONUs. In this paper, ONU-based multicast or multiple shared LAN emulation is used for IPTV channel package delivery services. Using ONU-based VLAN services, EPONs can support separate and secure connections between providers and subscribers in a simple manner. Also, IPTV channel packages can be delivered through EPONs by implementing ONU-based VLAN and IGMP snooping mechanisms. By showing fast channel zapping time of proposed architecture, I show that EPONs is suitable for IPTV channel package delivery service.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.663-665
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• 2004

Ethernet-based passive optical network(EPON) technology is being considered as a promising solution for next-generation broadband access network. It must have the property of high efficiency, low cost, and support quality of service(QoS). A major feature for this new architecture is the use of a shared transmission media between all connected optical network unit(ONU). Hence, medium access control(MAC) arbitration mechanisms are essential for the successful implementation of EPON. In this paper we propose a simple dynamic bandwidth allocation(DBA) algorithm that improves the performance of network and supports IP-based multimedia applications with the bursty data traffic. In addition, we introduce analytic models of proposed algorithms and prove the system based on our algorithm to be asymptotically stable. Simulation results show the new DBA algorithm provides high bandwidth efficiency and low queueing delay of ONU in EPON.

• Journal of the Korea Society of Computer and Information
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• v.23 no.12
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• pp.81-87
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• 2018

Cloud computing is a computing environment in which users borrow as many IT resources as they need to, and use them over the network at any point in time. This is the concept of leasing and using as many IT resources as needed to lower IT resource usage costs and increase efficiency. Recently, cloud computing is emerging to provide stable service and volume of data along with major technological developments such as the Internet of Things, artificial intelligence and big data. However, for a more secure cloud environment, the importance of perimeter security such as shared resources and resulting secure data storage and access control is growing. This paper analyzes security threats in cloud computing environments and proposes a security architecture for effective response.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.10
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• pp.24-33
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• 2001

Delay, delay variation and packet loss rate are principal QoS(Quality of Service) elements of packet communication. This paper proposes a new buffer allocation mechanism to improve the packet loss performance in such a situation that multiple logical buffers share a single physical memory buffer. In the proposed buffer allocation mechanism, the movement of dynamic threshold follows a curved track instead of a straight line which is used in the DT(dynamic threshold) mechanism. In order evaluate the effectiveness of the proposed mechanism, it is compared with the existing previously proposed mechanisms in several aspects including NC(no control), ST(Static Threshold) and DT mechanisms.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.671-676
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• 2012

Objectives: Screening for second primary cancer (SPC) is one of the key components of cancer survivorship care. The aim of the present study was to explore oncologists' experience with promoting second primary cancer screening. Methods: Two focus group interviews were conducted with 12 oncologists of diverse backgrounds. Recurrent issues were identified and placed into thematic categories. Results: Most of the oncologists did not consider SPC screening promotion as their responsibility and did not cover it in routine care. All of the study participants had experience with unexpected SPC cases, and they were under emotional tress. There was no systematic manner of providing SPC screening. Oncologists usually prescribe SPC screening in response to patients' requests, and there was no active promotion of SPC screening. Short consultation time, limited knowledge about cancer screening, no established guideline for SPC screening, and disagreement with patients about oncologists' roles were major barriers to its promotion. An institution-based shared care model was suggested as a potential solution for promoting SPC screening given current oncology practices in Korea. Conclusion: Oncologists could not effectively deal with the occurrence of SPC, and they were not actively promoting SPC screening. Lack of knowledge, limited health care resources, and no established guidelines were major barriers for promoting SPC screening to cancer survivors. More active involvement of oncologists and a systematic approach such as shared-care models would be necessary for promoting SPC screening considering increasing number of cancer survivors who are vulnerable.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.6
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• pp.1881-1900
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• 2014

Since 802.11 wireless LANs are so widely used, it has become common for numerous access points (APs) to overlap in a region, where most of those APs are managed individually without any coordinated control. This pattern of wireless LAN usage is called the private OBSS (Overlapping Basic Service Set) environment in this paper. Due to frame collisions across BSSs, each BSS in the private OBSS environment suffers severe performance degradation. This study approaches the problem from the perspective of congestion control rather than noise or collision resolution. The retry limit, one of the 802.11 attributes, could be used for traffic control in conjunction with TCP. Reducing the retry limit causes early discard of a frame, and it has a similar effect of random early drops at a router, well known in the research area of congestion control. It makes the shared link less crowded with frames, and then the benefit of fewer collisions surpasses the penalty of less strict error recovery. As a result, the network-wide performance improves and so does the performance of each BSS eventually. Reducing the retry limit also has positive effects of merging TCP ACKs and reducing HOL-like blocking time at the AP. Extensive experiments have validated the idea that in the OBSS environment, reducing the retry limit provides better performance, which is contrary to the common wisdom. Since our strategy is basically to sacrifice error recovery for congestion control, it could yield side-effects in an environment where the cost of error recovery is high. Therefore, to be useful in general network and traffic environments, adaptability is required. To prove the feasibility of the adaptive scheme, a simple method to dynamically adjust the value of the retry limit has been proposed. Experiments have shown that this approach could provide comparable performance in unfriendly environments.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.1
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• pp.109-126
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• 2014

The level of service (LOS) of the Highway Capacity Manual (KHCM) has been used as a basic criterion at decision making processes for signalized intersections in Korea. The KHCM provides five steps for the signalized intersection analysis. Among them, lane grouping, which is the third step, significantly influence the final LOS. The current method presented in the KHCM, however, classifies a shared lane as a de facto turning lane group, even though the turning traffic of the shared lane is few. Thus, this research was initiated to provide an alternative. To this end, three alternatives were suggested, including the method based on the lane grouping presented in the U.S. Highway Capacity Manual, the method using turning ratio of shared turning lane, and the method using a threshold traffic volume in lane grouping. The feasibilities of the three methods were evaluated using a calibrated CORSIM model. Conclusively, the method using a threshold traffic volume in lane grouping outperformed.

• Journal of Information Technology Applications and Management
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• v.20 no.3_spc
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• pp.259-278
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• 2013

At the center of the repeating evolution of IT industry, there is mobile computing in the ubiquitous environment, and the increasing usage of smart phones contribute more to its growth. P corporation co-developed with Google and implemented smart work system called SWP for the purpose of 'communication and collaboration with co-workers' beyond the general goal of increasing productivity and comfort of employees. The primary objective of this study is to objectively analyze the influence of the effect factor from end user's perspective and user satisfaction on SWP usage, intention for continuous usage and individual performance. To accomplish this research purpose, this study established research models and hypothesis by collective review about information system success models, and tested the research hypotheses using the structural equation modeling technique by data collected from 320 SWP system users of P corporation. Variations for system satisfaction evaluation standard are 1)SW system usage 2) intention for continuous usage 3) individual performance, effect variations are 1) social factors 2) technical factors 3) combination of social and technical factors. Therefore, this study is about influence factors on success of SWP system and how the factors impact the outcome. The test results of this research model is summarized as follows. Firstly, system user's satisfaction had positive impact on all three; SWP system usage, intention for continuous usage and individual performance. Secondly, social factor 'SWP control system' and technical factor 'information quality' and 'system quality' had positive impact on SWP system user satisfaction, while social factor 'shared value' and technical factor 'service quality' did not have significant effect on user satisfaction. Shared value however, had interactive effect with 'information quality' and 'service quality'. This study is expected to contribute to spread of academic research on smart work system by suggesting a model that can show important factors for corporation while explaining the successful implementation of SWP and its continuous usage.