• Journal of KIISE:Information Networking
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• v.37 no.4
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• pp.284-293
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• 2010

For the successful deployment of Mobile Internet, fast handover technologies are essential. For the past few years several handover mechanisms are suggested, and Fast Handover for Proxy Mobile IPv6 (PFMIPv6) is one of the promising schemes for this purpose. In this paper, we propose a novel L2/L3 cross layer handover scheme based on ARIMA prediction model to apply PFMIPv6 to Mobile Internet environment effectively. Performance gains are evaluated in terms of probabilities of predictive-mode operation, handover latencies, packet loss probabilities, and signaling costs. Three mobilities models are used for our simulation: Manhattan Model, Open Area Model, and Freeway Model. Simulation results show that the proposed scheme can increase probabilities of predictive-mode operation and reduce handover latency, packet loss probabilities, and signaling cost.

• Journal of Korea Port Economic Association
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• v.29 no.4
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• pp.73-95
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• 2013

This paper analyzes a competitive shipping market in East Asia in order to explore how container carriers make decisions on ship size, number of ships, service frequency, and service route. A sequential-move game based on non-cooperative game theory is applied to establish the models for the decision-makings involving the transportation volumes, freight rates, costs, and market shares of the service routes from Shanghai or Hong Kong to the ports in Busan, Gwangyang, and Incheon. According to the sub-game perfect Nash equilibrium solutions proposed by these models, carriers' decisions in such a competitive environment vary depending on sailing distance, transport demand, and freight rates. Therefore, carriers are recommended to reflect the optimal equilibrium solutions and a variety of decision factors when formulating strategies for transportation networks and operating fleets. Furthermore, ports should establish management strategies for these factors to provide optimal equilibrium solutions for carriers' transportation networks.

• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.6-11
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• 2016

In this paper, we have analyzed the effects of co-channel, adjacent-channel, and the human shield(Body Blockage) for wideband WLAN based on the IEEE802.11n 40MHz channel bandwidth required for high speed digital signage service. Simulation results show that wideband WLAN can be operated with 78 interferers over 63m distance in co- channel, 80 interferer over 61m distance in adjacent channel. By applying the mitigation method for reducing the interference, we have confirmed that protection distance is improved to 51m using beamforming, and 40m using cognitive radio in co-channel interference. Also body blockage interference is reduced using adaptive channel bandwidth, C/I ratio, beamforming, power control mitigation methodology.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.450-459
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• 2004

This paper studies the collective communication in the grid computing environment, which is characterized by the combination of heterogeneous networks as well as uneven, long communication delay. Efficient collective communication requires communication schedule, which in turn requires network information. When the network information is not accurate or network faults occur, the performance of collective communication can be markedly degraded. This paper proposes TTCC(Two-Tree Collective Communication) for scheduling collective communication in the grid. It Provides an efficient and reliable schedule even In this unfavorable network condition by maintaining two disjoint communication trees. Benefits of the proposed method are manifested via simulation, where the performance degradation with TTCC is much slower than those using conventional scheduling algorithms.

• The Journal of the Korea Contents Association
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• v.15 no.1
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• pp.276-285
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• 2015

The aim of this study was to identify the impact of community factors on the community-level Health-Related Quality of Life (HRQOL) in Korea. This was a cross-sectional study conducted in 2012 using secondary data(n=209) of the Korean Statistical Information Service. The framework was based on community factors provided by the International Council of Science (ICSU) and community factors were categorized based on six aspects. Multiple regression was applied to community factors depending on the community EQ-5D index. Smoking rate, "Good" self-rated health rate, water and wastewater coverage rate, and financial independency rate were significantly and positively associated with the EQ-5D score. Net migration rate(more move out than move in), obesity rate, unmet needed health care rate, and community type(rural than urban) were significantly and negatively associated with the EQ-5D score. This study identifies association for the impact of community factors on the community-level HRQOL and can provide useful evidence for development of community health promotion policies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.339-348
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• 2004

Packet classification is an important factor to support various services such as QoS guarantee and VPN for users in Internet. Packet classification is a searching process for best matching rule on rule tables by employing multi-field such as source address, protocol, and port number as well as destination address in If header. In this paper, we propose hardware based packet classification algorithm by employing tree bitmap of multi-bit trio. We divided prefixes of searching fields and rule into multi-bit stride, and perform a rule searching with multi-bit of fixed size. The proposed scheme can reduce the access times taking for rule search by employing indexing key in a fixed size of upper bits of rule prefixes. We also employ a marker prefixes in order to remove backtracking during searching a rule. In this paper, we generate two dimensional random rule set of source address and destination address using routing tables provided by IPMA Project, and compare its memory usages and performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1701-1710
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• 2012

Recently, it has been found that it is important to use a smart grid to reduce greenhouse-gas emissions worldwide. A smart grid is a digitally enabled electrical grid that gathers, distributes, and acts on information regarding the behavior of all participants (suppliers and consumers) to improve the efficiency, importance, reliability, economics, and sustainability of electricity services. The smart grid technology uses two-way communication, where users can monitor and limit the electricity consumption of their home appliances in real time. Likewise, power companies can monitor and limit the electricity consumption of home appliances for stabilization of the electricity supply. However, if information regarding the measured electricity consumption of a user is leaked, serious privacy issues may arise, as such information may be used as a source of data mining of the electricity consumption patterns or life cycles of home residents. In this paper, we propose a data transaction protocol for privacy protection in a smart grid. In addition, a power company cannot decrypt an encrypted home appliance ID without the user's password.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.193-198
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• 2017

Recently, as interest in health increases, various wearable devices such as smart watch and smart band which can measure user's biometric information are being studied. Conventional wearable devices service the measured biometric information in a form that provides simple monitoring, disease prevention, and exercise amount. However, the user is Lack to deal with the dangerous situation. In this paper, we propose a hazard notification system to address these problems. The biometric information measured by the acceleration sensor and the heart rate sensor is transmitted to the application through the Arduino in real time. It identifies the risk situation through sensor priority measurement and risk situation identification algorithm. If a dangerous situation occurs, a notification message is sent to the guardian indicating the current location of the user. Therefore, it can be expected that if a dangerous situation occurs to a user who needs protection, he can respond promptly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.403-410
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• 2004

In general communication system is composed of processor subsystems, I/O processor subsystems and data storage device subsystems those are classified as their functions. In order to improve the data reliability, all subsystems are redundant. Storage device keeps the operational information such as system related information and charging information, and such informations must be stored in non-volatile memory. Flash memory and battery backup memory are commonly used as the non-volatile storage devices. But such kind of memories are expensive per unit capacity and data can't be restored when lost while not being backed up. In this paper we develop a redundant storage device to store a lot of data safely and reliably in communication system. The device consists of micro-controller, FPGA and hard disk It provides many functions those are rebuilding, automatic remapping, host service and remote host service. Also it is designed to provide host service while rebuilding is being done in order not to interrupt the communication services. The developed device can be used instead of expensive storage device like flash memory in various communication systems.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.157-165
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• 2004

The paper suggests that web-server security management system will be able to detect the web service attack accurately and swiftly which is keeping on increasing at the moment and reduce the possibility of the false positive detection. This system gathers the results of many unit security modules at the real time and enhances the correctness of the detection through the correlation analysis procedure. The unit security module consists of Network based Intrusion Detection System module. File Integrity Check module. System Log Analysis module, and Web Log Analysis and there is the Correlation Analysis module that analyzes the correlations on the spot as a result of each unit security module processing. The suggested system provides the feasible framework of the range extension of correlation analysis and the addition of unit security module, as well as the correctness of the attack detection. In addition, the attack detection system module among the suggested systems has the faster detection time by means of restructuring Snort with multi thread base system. WSM will be improved through shortening the processing time of many unit security modules with heavy traffic.