• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.86-96
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• 2006

In recent year, EPON(Ethernet PON) system is expected to be more attractive solutions for high speed, broadband access networks in next generation access networks due to the conversionce of low-cost ethernet equipment and low-cost fiber infrastructure. Upstream channel control algorithm is essential to hare upstream bandwidth in EPON. In this paper, we suggest HUHG(High Utilization and Hybrid Granting) algorithm for supporting high bandwidth utilization and QoS for different service class. This algorithm improves bandwidth utilization as removing or diminishing idle time of upstream channel using characteristics of fixed EF(Expedited Forwarding) sub-cycle. The proposed algorithm also minimizes the packet delay and delay variation of EF class. We conduct detailed simulation experiments using OPNET to study the performance and validate the effectiveness of the proposed algorithm.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.1
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• pp.1-8
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• 2016

The Nuclear Power Plants(: NPP) are being protected as national infrastructure, and instrumentation and control(: I&C) systems are one of the principle facilities of the NPP, which perform the protection, control, and monitoring function. The I&C systems are being evolved into digitalization based on computer and network technology from analog system. In addition, the I&C systems are mostly employ the specialized logic controllers which are dedicated for the NPP, but the usage of generalized IT resources are steadily increased. The cyber security issues for the NPP are being emerged due to cyber incidents by Stuxnet and various accidents in the NPP. In this paper, hybrid access control model is proposed which are applicable to I&C system by analyzing the access control requirements specified in regulatory guides. The safety of in-service and under construction of NPP are effectively increased by applying proposed hybrid model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.718-723
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• 2017

We propose a pilot hopping scheme that improves the limited system capacity due to pilot contamination in multi-cell environment with large-scale antenna arrays at a base station, assuming the infinite number of antennas. In the conventional fixed pilot scheme, each user obtains the same signal-to-interference ratio (SIR) over a long period of time. Therefore, a user with strong interference has continuously low SIR which degrades its service quality. In the proposed pilot hopping scheme, different pilot signals are used for each time slot, and different amounts of interference are received every time. When such a pilot hopping technique is applied, the SIR fluctuates at every time slot. When the Hybrid Automatic Repeat & reQuest (HARQ) technique is applied in such a channel, the outage probability and transmission rate are improved. We show that there is the performance gain of the proposed scheme over the conventional scheme through computer simulations.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.4 no.1
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• pp.67-88
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• 2009

The purpose of this study IS to suggest the failure factors and the success factors of technology-based startups(TBS). This study surveyed 327 startup companys on the general obstacles of starting business and the entrepreneurship policy of the Government. The failure factors of TBS are 1) overconfidence of TBS in their technology, 2) lack of cost management, 3) lack of concentration on the sales revenue of their activies, 5) many unplanned challenges, and 5) lack of strategic decision. And the success factors of TBS are 1) CEO's leadership having a clear business concept, 2) development of innovative products and services, 3) flat and flexible organization structure, 4) leveraging outside business resources and networks, and 5) strengthening the human resources by the hybrid agent.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.5
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• pp.19-28
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• 2012

Recently a grid and cloud computing collaboration have become a social issue. These collaborative network system, the P2P system based on this system. Distingui shed from the client/server systems, P2P systems in order to exchange information, its purpose and functions are divided according to the morphological Category. In accordance with the purposes and functions of information and data retrieval, remote program control and integration services for the offers. Most P2P systems client/server scalability, and management takes the form, but to overcome the disadvantages in terms of applying the mixed-mode system is increasing. And recently the distributed computing aspects of the service to users in order to provide suitable to accommodate the diverse needs of various types of mobile agent technology is needed. In this paper, as required by the mobile agent access to a remote resource access control and agent for the execution and management capabilities and improve the reliability of the mobile agent system designed to suggest.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.131-137
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• 2014

The advent of various smart devices like smart phones and tablets has triggered the changes in information systems of medical centers. Especially, diversifying devices of clients and the need for N-Screen services increase necessities for sharing effectively information in medical centers. However, developing and managing clients for each OS like iOS and Android cost high and make it hard to provide seamless service through multi devices. Also, in the aspect of security it is necessary to share information between clients and health information systems. In this paper, we develop a smart health information client based real-time health information sharing framework. The developed client is based on hybrid app, that enables to share information in real time between N devices through health information sharing framework and to adopted to developments of various clients.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.177-182
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• 2016

Geofence is a generic concept for describing geographic aspects of PoI(Point of Interest) enabling users to proactively induce context-based actions. However there is no need to maintain continuity when you reflect geofence in case of temporary events, accidents and isolation. Therefore we propose a geofence platform so-called TemG by adding time-limited information to support PoI. The proposed geofence platform TemG ensures the persistency and continuity of geofence. Furthermore, the proposed TemG can not only provide to automatically activate or deactivate the specified geofence during a period of timestamp but also support to the basic context-aware service knowing in/out in the zone. In the near future, the proposed TemG will be need to extend HPS(Hybrid Positioning System) for IoT(Internet of Things).

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.44-51
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• 2013

Routers should perform fast IP address lookup for Internet to provide high-speed service. In this paper, we present a hybrid parallel IP address lookup structure composed of four-stage pipeline. It achieves parallelism at low cost by using multiple SRAMs in stage 2 and partitioned TCAMs in stage 3, and improves the performance through pipelining. The smart distributor in stage 1 does not transfer any IP address identical to previous one toward the next stage, but only uses the result of the previous lookup. So it improves throughput of lookup by caching effects, and decreases the access conflict to TCAM bank in stage 3 as well. In the last stage, the reorder buffer rearranges the completed IP addresses according to the input order. We evaluate the performance of our parallel pipelined IP lookup structure comparing with previous hybrid structure, using the real routing table and traffic distributions generated by Zipf's law.

• Journal of Korean Academy of Nursing
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• v.50 no.2
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• pp.178-190
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• 2020

Purpose: The purpose of this study was to identify trends of nursing concept development in Korean journal papers to improve accurate understanding of nursing concepts. Methods: A systematic review of 216 concept development articles published from 1970 to 2018 that met the inclusion criteria was conducted using Research Information Sharing Service (RISS) databases. Results: The most common method of concept development was Walker and Avant's concept analysis method, identified in 139 (64.3%) of the 216 studies, followed by 48 examples of hybrid models (22.2%) and 15 examples of evolutionary methods (6.9%). Chinn and Kramer's method, Norris's clarification, Wilson's method, and others were also used. The concepts of "spirituality" and "fatigue" were most frequently analyzed. Among the 139 studies that used Walker and Avant's concept analysis method, 127 studies (91.4%) applied all the recommended steps; the others applied the recommended steps partially, omitting description of model cases/additional cases, antecedents/consequences, and empirical indicators. Among the studies using the hybrid model, among two (5.7%) did not describe attributes, three (8.5%) did not provide definitions, and 16 (45.7%) did not present empirical indicators in the final stage. Conclusion: Among concept development studies published in Korean journals, Walker and Avant's concept analysis method is most commonly used. In case of most studies using Walker and Avant's method a suitable concept analysis process is applied, but in case of other studies using the other concept development method, a suitable concept analysis process is not applied. Therefore, a suitable concept analysis process must be applied for concept development in nursing research.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.115-125
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• 2005

This paper discusses how to effectively design a next-generation wireless communication system that can possibly provide very high data-rate transmissions and versatile quality services. In order to accommodate the sophisticated user requirements and diversified user environments of the next-generation systems, it should be designed to take an efficient and flexible structure for multiple access and resource allocation. In addition, the design should be optimized for cost-effective usage of resources and for efficient operation in a multi-cell environment. As orthogonal frequency division multiple access (OFDMA) has turned out in recent researches to be one of the most promising multiple access techniques that can possibly meet all those requirements through efficient radio spectrum utilization, we take OFDMA as the basic framework in the next-generation wireless communications system design. So, in this paper, we focus on introducing an OFDMA-based downlink system design that employs the techniques of hybrid multiple access (HMA) and frequency group (FG) in conjunction with intra-frequency group averaging (IFGA). The HMA technique combines various multiple access schemes on the basis of OFDMA system, adopting the multiple access scheme that best fits to the given user condition in terms of mobility, service, and environment. The FG concept and IFGA technique help to reduce the feedback overhead of OFDMA system and the other-cell interference (OCI) problem by grouping the sub-carriers based on coherence band-widths and by harmonizing the channel condition and OCI of the grouped sub-carriers.