• The KIPS Transactions:PartD
• /
• v.12D no.4 s.100
• /
• pp.521-530
• /
• 2005

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the Portability of mobile clients. Mobile computing satisfies user's demands for convenience and Performance to use information at any time and in any Place, but it has many Problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Query Processing System(MQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client-server environments. In addition, we proved the superiority of the proposed MQPS by comparing its performance to the C-I-S(Client-Intercept- Server) model.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.4
• /
• pp.99-107
• /
• 2012

We propose control mechanism of UAV(Unmanned Aerial Vehicle) group for making the communication network to the base station after the target is found. We assume UAVs can communicate to each other by wireless LAN without existing communication infrastructure. UAVs started to fly in linear formation, after finding target, UAVs move to the base station to send the information about the target. At least one UAV stays the position that the target is found. This paper explains the mechanism supporting reliable connectivity during UAV group's flying. We verify the proposed scheme and evaluate the performance through NS-2 simulation. The proposed scheme can be applied to the disaster area and war zone, which the existing communication infrastructure cannot be worked.

• Human Ecology Research
• /
• v.55 no.4
• /
• pp.441-450
• /
• 2017

Childcare related studies have focused on the characteristics of care work, policy aspects, user family satisfaction, and job satisfaction of childcare helpers. But there have been few studies on family system characteristics that support childcare givers. Thus, this study conducted on the topic, "How to characterize the family resilience of long-term childcare givers?" The subjects belong to a healthy family support center in U. City, who belong to a group with an income in the top 20 % of about 20 persons working for more than 3 years. In an interview, qualitative questions were used Walsh's family resilience. The results are as follows. First, they had economic hardship, but their family would stand together and build up a family's power based on the couple's faith. They had a family role model based on their parents' family that included inherited maternity qualities from their mother. Second, the flexibility of the family organization changed to autonomous or co-role type and the connectivity. Especially, they appear as a family's leader. Third, their family communication was active, shared-care, responsible and passionate with family affection and understanding. The conclusions results are as follows. Participants were high school graduates as well as had work experience. They were characterized by positive family energy, a family belief system, family-based resources, flexibility, connectivity, open family communication and expression skills. Therefore, it can be suggested that it is necessary to check the family's resilience during an interview for the reliable, long-term supply of human resources for childcare activities.

• ETRI Journal
• /
• v.42 no.5
• /
• pp.669-685
• /
• 2020

5G AgiLe and fLexible integration of SaTellite And cellulaR (5G-ALLSTAR) is a Korea-Europe (KR-EU) collaborative project for developing multi-connectivity (MC) technologies that integrate cellular and satellite networks to provide seamless, reliable, and ubiquitous broadband communication services and improve service continuity for 5G and beyond. The main scope of this project entails the prototype development of a millimeter-wave 5G New Radio (NR)-based cellular system, an investigation of the feasibility of an NR-based satellite system and its integration with cellular systems, and a study of spectrum sharing and interference management techniques for MC. This article reviews recent research activities and presents preliminary results and a plan for the proof of concept (PoC) of three representative use cases (UCs) and one joint KR-EU UC. The feasibility of each UC and superiority of the developed technologies will be validated with key performance indicators using corresponding PoC platforms. The final achievements of the project are expected to eventually contribute to the technical evolution of 5G, which will pave the road for next-generation communications.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.7
• /
• pp.2631-2649
• /
• 2021

Device-to-Device (D2D) communication is one of the enabling technologies for 5G networks that support proximity-based service (ProSe) for wireless network communications. This paper proposes a power control algorithm based on the Nash equilibrium and game theory to eliminate the interference between the cellular user device and D2D links. This leadsto reliable connectivity with minimal power consumption in wireless communication. The power control in D2D is modeled as a non-cooperative game. Each device is allowed to independently select and transmit its power to maximize (or minimize) user utility. The aim is to guide user devices to converge with the Nash equilibrium by establishing connectivity with network resources. The proposed algorithm with pricing factors is used for power consumption and reduces overall interference of D2Ds communication. The proposed algorithm is evaluated in terms of the energy efficiency of the average power consumption, the number of D2D communication, and the number of iterations. Besides, the algorithm has a relatively fast convergence with the Nash Equilibrium rate. It guarantees that the user devices can achieve their required Quality of Service (QoS) by adjusting the residual cost coefficient and residual energy factor. Simulation results show that the power control shows a significant reduction in power consumption that has been achieved by approximately 20% compared with algorithms in [11].

• Journal of the Korean Society of Radiology
• /
• v.15 no.4
• /
• pp.507-518
• /
• 2021

Magnetic resonance imaging (MRI) is a key technology that has been seeing increasing use in studying the structural and functional innerworkings of the brain. Analyzing the variability of brain connectome through tractography analysis has been used to increase our understanding of disease pathology in humans. However, there lacks standardization of analysis methods for small animals such as mice, and lacks scientific consensus in regard to accurate preprocessing strategies and atlas-based neuroinformatics for images. In addition, it is difficult to acquire high resolution images for mice due to how significantly smaller a mouse brain is compared to that of humans. In this study, we present an Allen Mouse Brain Atlas-based image data analysis pipeline for structural connectivity analysis involving structural region segmentation using mouse brain structural images and diffusion tensor images. Each analysis method enabled the analysis of mouse brain image data using reliable software that has already been verified with human and mouse image data. In addition, the pipeline presented in this study is optimized for users to efficiently process data by organizing functions necessary for mouse tractography among complex analysis processes and various functions.

• Architectural research
• /
• v.12 no.1
• /
• pp.9-14
• /
• 2010

The present study explored the applicability of Visibility Graph Analysis (VGA) techniques to workplace design research. Six types of VGA measures in Depthmap encompassing visual connectivity, three types of visual integration, mean depth, and visual entropy were employed for the analysis of individual privacy for task concentration and group relationship behavior in the open-plan office environment. Data comprised 136 workers in 6 open-plan offices filled with low-paneled (1.2-1.5m) cubicle workspaces. For the statistical analysis, Spearman's rho correlations and t-tests were applied for the spatial and behavioral measures. The results showed that workspace VGA measures have a potential to be useful information to account for workers' concentration privacy and, limitedly, also informal relationships with team members. Visual entropy values especially offer reliable information to predict various aspects of office workers' privacy behavior while visual integration can be used to account for the workers' sense of trust in group relations. The study also discussed the limitation of VGA applications to the workplace context.

• The Korean Journal of Physiology and Pharmacology
• /
• v.13 no.3
• /
• pp.221-227
• /
• 2009

For successful restoration of visual function by a visual neural prosthesis such as retinal implant, electrical stimulation should evoke neural responses so that the informat.ion on visual input is properly represented. A stimulation strategy, which means a method for generating stimulation waveforms based on visual input, should be developed for this purpose. We proposed to use the decoding of visual input from retinal ganglion cell (RGC) responses for the evaluation of stimulus encoding strategy. This is based on the assumption that reliable encoding of visual information in RGC responses is required to enable successful visual perception. The main purpose of this study was to determine the influence of inter-dependence among stimulated RGCs activities on decoding accuracy. Light intensity variations were decoded from multiunit RGC spike trains using an optimal linear filter. More accurate decoding was possible when different types of RGCs were used together as input. Decoding accuracy was enhanced with independently firing RGCs compared to synchronously firing RGCs. This implies that stimulation of independently-firing RGCs and RGCs of different types may be beneficial for visual function restoration by retinal prosthesis.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.8
• /
• pp.547-553
• /
• 2006

We present a new geometry coding method for 3D meshes, an adaptive subdivision. Previous localized geometry coding methods have demonstrated better compression ratios than the global approach but they are considered hard to use in practice partly due to time - consuming quantization. Our new localized scheme replaces this quantization with an adaptive subdivision of the localized range. The deeper level a user chooses, the closer to the original the mesh will be restored. We also present an improved connectivity coder upon the current leading Angle-Analyzer's by applying a context-modeling. As a result, our new coder provides reliable and intuitive controls between bit-rate and distortion without losing efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.11B
• /
• pp.1676-1684
• /
• 2010

Tactical network environments are characterized by unreliable connectivity, communication links which has limited bandwidth compared to commercial networks and distributed architecture where users have high mobility. The best route should be selected based on the required traffic characteristics which can be a wireless channel environments and a status of nodes which are moving. Those characteristics are self aware and should be a routing decision factor in order to guarantee a reliable data transfer. In this paper we define the requirements of services and traffic characteristics on tactical network environments and suggest the new routing method "AODV-IMTC" based on selective routing metric to enable efficient data transfer in wireless ad hoc networks.