• Journal of Industrial Technology
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• v.27 no.B
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• pp.43-51
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• 2007

In mobile multi-hop wireless networks, the authentication between a base station and a mobile multi-hop node, between multi-hop nodes, and between user a station and a multi-hop node is needed for the reliable and secure network operation. In this paper, we survey various authentication schemes which can be considered to be adopted in mobile multi-hop wireless networks and propose a concept of novel mutual authentication scheme applicable to mobile multi-hop network architecture. The scheme should resolve the initial trust gain problem of a multi-hop node at its entry to the network, the problem of rogue mobile multi-hop node and the problem of hop-by-hop authentication between multi-hop nodes. Effectively, the scheme is a hybrid scheme of the distributed authentication method and the centralized authentication method which are considered to be deployed in the wireless ad-hoc network and the wireless network connected to wired authentication servers, respectively.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.1
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• pp.56-66
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• 2011

The purpose of this study is in analyzing factors related to a teacher's nursery efficacy. In order to achieve its purpose, a study includes investigation about levels of 748 teachers' interest and knowledge in a child nursery from multi-cultural families, teachers' efforts for understanding the children from multi-cultural families, availability of experience with a child care from multi-cultural families, a teacher's multi-cultural nursery efficacy and general nursery efficacy. As a result of investigation, a study found out that 4 factors (interest, knowledge, efforts, and experience) are related to nursery efficacy and the fact that a teacher's general nursery efficacy is highly associated with multi-cultural nursery efficacy. For this result, providing information about a child care from multi-cultural families and supporting general nursery efficacy play a critical role in supporting teachers' competency about a child care from multi-cultural families.

• Communications of the Korean Mathematical Society
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• v.39 no.3
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• pp.673-692
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• 2024

In this work, an alternative fashion of the multi-Jensen is introduced. The structures of the multi-Jensen and the multi-Euler-Lagrange-Jensen mappings are described. In other words, the system of n equations defining each of the mentioned mappings is unified as a single equation. Furthermore, by applying a fixed point theorem, the Hyers-Ulam stability for the multi-Euler-Lagrange-Jensen mappings in the setting of Banach spaces is established. An appropriate counterexample is supplied to invalidate the results in the case of singularity for multiadditive mappings.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1091-1096
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• 2015

In this paper, WiMedia Distributed-MAC protocol is adopted for development of multi-hop N-screen wireless services. Furthermore, to provide the multi-hop OSMU (One Source Multi Use) N-screen service through P2P streaming in the D-MAC protocol, a new multi-hop resource reservation scheme is proposed and analyzed to reduce end to end delay. For this Multi-hop resource reservation scheme, a new MSCDRP (Multi-Stage Cooperative DRP) IE is proposed. Simulation results show that our multi-hop MSCDRP scheme reduces the end to end delay and increases throughput at various multi-hop N-screen network environment.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.1
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• pp.157-170
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• 2012

Recently, user-created video shows high increasing in production and consumption. Among these, videos records an identical subject in limited space with multi-view are coming out. Occurring main reason of this kind of video is popularization of portable camera and mobile web environment. Multi-view has studied in visually representation technique fields for point of view. Definition of multi-view has been expanded and applied to various contents authoring lately. To make user-created videos into multi-view contents can be a kind of suggestion as a user experience for new form of video consumption. In this paper, we show the possibility to make user-created videos into multi-view video content through analyzing multi-view video contents even there exist attribute differentiations. To understanding definition and attribution of multi-view classified and analyzed existing multi-view contents. To solve time axis arranging problem occurred in multi-view processing proposed audio matching method. Audio matching method organize feature extracting and comparing. To extract features is proposed MFCC that is most universally used. Comparing is proposed n by n. We proposed multi-view video contents that can consume arranged user-created video by user selection.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.8-15
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• 2006

Separation control has been performed using the multi-array/multi-location synthetic jet on NACA23012 at high angle of attack. The flow control using single synthetic jet shows that stall characteristics can be substantially improved with delayed separation point. Theses results show the characteristic of unsteady flow of single synthetic jet. Beside, we researched on multi-array synthetic jet to obtain applicable synthetic jet velocity. Multi-location synthetic jet is proposed to eliminate small vortex on suction surface of airfoil. With the results, we concluded that the flow around airfoil is stable by high frequency synthetic jet with elimination of small vortex and confirmation of stable flow. Moreover, performance of multi-array/multi-location synthetic jet can be improved by changing phase angle of multi-location synthetic jet.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1065-1071
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• 2005

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method (FEM). We evelop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi­stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multi layers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.488-501
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• 2008

Convergence of various wireless systems can be cost effectively achieved through enhancement of existing technology. The emergence of Wireless Mesh Network (WMN) entails the interoperability and interconnection of various wireless technologies in one single system. Furthermore, WMN can be implemented with multi-radio and multi-channel enhancement. A multi-radio, multi-channel wireless mesh network could greatly improve certain networking performance metrics. In this research, two approaches namely, clustering and topology control mechanisms are integrated with multi-radio multi-channel wireless mesh network. A Clustering and Topology Control Algorithm (CTCA)is presented that would prolong network lifetime of the client nodes and maintain connectivity of the routers.

• KCID journal
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• v.21 no.1
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• pp.109-117
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• 2014

Multi water-loop system is the efficient customer centered facilities of water supply by utilizing the multi water resources. Multi water-loop system is divided into various types. The system is classified potable and non-potable type. Mostly, the potable type utilizes surface water and ground water. However, the non-potable type utilize the multi water resources, such as rain water, sea water, reclaimed water, etc. Selective intake is possible when characteristics of region, physiographic condition and purpose of use are considered. For instance, downtown type, new-city type, agriculture type, island type are available. For development and application of these multi water-loop system, standardization is needed. For standardization, several methods are given; design principles, selection and composition method of multi water-loop system structure, BIM/GIS application method, safety inspection method. Consequently, a road map of design standardization method can be established. In this road map, there are three parts for the standardization of multi water-loop system. Three parts are the considerations, base material and ways of standardization. Design standardization become close when this road map followed by someone who plan the multi water-loop system. In this way, loop system's development is more efficient and economic. In hereafter research, each type's characteristic will be analysed and standardization methods can be established.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.7
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• pp.513-519
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• 2011

The object of this study is to investigate the performance characteristics of refrigerators using a single-circuit multi cycle and a bypass two-circuit multi cycle. Each refrigeration cycle was tested by varying secondary fluid mass flow rate and temperature. Based on the experimental data, the optimum refrigerant charge was 48 g and the COP at the optimum secondary fluid mass flow rate was 1.53 for the single-circuit multi cycle. For freezer(F)-only mode, both the single-circuit multi cycle and the bypass two-circuit multi cycle were operated at overcharge conditions, resulting in an increase of the secondary fluid mass flow rate. The maximum COPs of the single-circuit multi cycle and the bypass two-circuit multi cycle were 1.22 and 1.35, respectively. The COP increased by 10.7% with the application of the bypass two-circuit multi cycle.