• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.133-136
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• 2003

In this paper, we propose a multicast routing protocol for the seamless delivery of multicast data to mobile hosts through the optimal route in IP based mobile networks. The proposed multicast routing protocol is a hybrid method employing the merits of the bi-directional tunneling and the remote subscription by considering the mobility of mobile hosts. The proposed protocol satisfies the bound of end-to-end delay and supports the seamless handoff. The simulation results show that the proposed protocol has better performance in the number of multicast tree reconstruction and tunneling length and packet loss time than the previous protocols.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.148-149
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• 2007

• KDI Journal of Economic Policy
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• v.26 no.1
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• pp.141-190
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• 2004

Income inequality in Korea has increased after the economic crisis, and the main reason for the widening of income distribution is due to the increase of the unemployed when analyzed using the Urban Household Report(UHR). However, income inequality has not decreased although the rate of unemployment decreased after 2000. Further data bases for income-related statistics are necessary to examine the exact causes of changing income inequality as a whole since the UHR covers only statistics on urban employees' wage and salary in Korea.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.452-452
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• 2004

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.1-9
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• 2017

Recently, the active research into wireless sensor networks has led to the development of sensor nodes with improved performance, including their mobility and location awareness. One of the most important goals of such sensor networks is to transmit the data generated by mobile sensors nodes. Since these sensor nodes move in the mobile wireless sensor networks (MWSNs), the energy consumption required for them to transmit the sensed data to the fixed sink is increased. In order to solve this problem, the use of mobile sinks to collect the data while moving inside the network is studied herein. The important issues are the mobility and energy consumption in MWSNs. Because of the sensor nodes' limited energy, their energy consumption for data transmission affects the lifetime of the network. In this paper, a mobile-sink based energy-efficient clustering scheme is proposed for use in mobile wireless sensor networks (MECMs). The proposed scheme improves the energy efficiency when selecting a new cluster head according to the mobility of the mobile sensor nodes. In order to take into consideration the mobility problem, this method divides the entire network into several cluster groups based on mobile sinks, thereby decreasing the overall energy consumption. Through both analysis and simulation, it was shown that the proposed MECM is better than previous clustering methods in mobile sensor networks from the viewpoint of the network energy efficiency.

• Construction Engineering and Management
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• v.19 no.2
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• pp.63-68
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• 2018

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1431-1439
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• 2016

In this paper, we propose a new location service and location-based routing for data dissemination from a source to a mobile group sink in less energy consumption of the sensor node. Unlike the existing protocols, the proposed protocol uses a leader sink instead of a group area as the location information to represent a mobile sink group. The proposed protocol also uses grid leaders on virtual grid structure to support sink mobility in location service. By using a leader sink as a representative and grid leaders for mobility supporting, the proposed protocol can exploit an efficient hierarchical location service and data dissemination method without using flooding. Accordingly, the proposed protocol carries out upper layer location services and data dissemination between a leader sink and a source and lower layer location services and data dissemination between the leader sink and member sinks. Simulation results demonstrate that the proposed protocol achieves energy-efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2473-2492
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• 2012

Energy conservation is a vital issue in wireless sensor networks. Recently, employing mobile sinks for data gathering become a pervasive trend to deal with this problem. The sink can follow stochastic or pre-defined paths; however the controlled mobility pattern nowadays is taken more into consideration. In this method, the sink moves across the network autonomously and changes its position based on the energy factors. Although the sink mobility would reduce nodes' energy consumption and enhance the network lifetime, the overhead caused by topological changes could waste unnecessary power through the sensor field. In this paper, we proposed EEDARS, an energy-efficient dual-sink algorithm with role switching mechanism which utilizes both static and mobile sinks. The static sink is engaged to avoid any periodic flooding for sink localization, while the mobile sink adaptively moves towards the event region for data collection. Furthermore, a role switching mechanism is applied to the protocol in order to send the nearest sink to the recent event area, hence shorten the path. This algorithm could be employed in event-driven and multi-hop scenarios. Analytical model and extensive simulation results for EEDARS demonstrate a significant improvement on the network metrics especially the lifetime, the load and the end-to-end delay.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.20 no.3
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• pp.220-229
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• 2013

Purpose: The purpose of the study was to investigate activities-specific balance confidence and risk of fallings among rehabilitation patients with impaired of mobility, and to identify the influence of activities-specific balance confidence on their risk of fallings. Method: Data for 132 rehabilitation patients were collected between October June 20 and August 20, 2012 at nine hospitals in a metropolitan city. Data were analyzed using t-test, ANOVA, Pearson correlation coefficient and stepwise multiple regression with SPSS/WIN 20.0. Result: The mean score for rehabilitation patients' activities-specific balance confidence was 40.18 out of a possible range of 0-100 and the mean score for risk of fallings among rehabilitation patients was 31.10 within a possible range of 0-125. Significant factors affecting the risk of fallings among the rehabilitation patients were 'activity level', 'dementia', 'body mass index', 'anxiety', and 'presence of a caregiver', which together explained 34.7% of the variance. The most significantly factor influencing rehabilitation patients' risk of fallings was activities-specific balance confidence which explained 23.5% of the variance. Conclusion: The study results indicate that activities-specific balance confidence as well as physical factors should be considered for interventions to decrease risk of fallings in rehabilitation patients with impaired mobility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.615-622
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• 2009

In this paper, we consider the problem of applying NEMO in PMIPv6, and propose a method to support network mobility. When an MR enters a PMIPv6 domain, an MAG recognizes the MR to access using the BU message. And the MAG makes a tunnel between the MAG and the MR. The MR do not make tunnel fundamentally except for handover. Therefore, the PMIPv6 protocol needs to modify the original algorithm and the BCE data filed. However, the proposed method can use NEMO without protocol modification. To show verification, we implement our proposed algorithm with added BCE data filed using C program, and configure a testbed network. Through a network connectivity procedure, we can see that our proposed method can support network mobility within the PMIPv6 network.