• Journal of IKEEE
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• v.16 no.2
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• pp.86-94
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• 2012

Synchronization MAC Protocol such as S-MAC and T-MAC utilize duty cycling technique which peroidically operate wake-up and sleep state for reducing energy consumption. But synchronization MAC showed low energy efficiency because of additional control packets. For better energy consumption, Asychronization MAC protocols are suggested. For example, B-MAC, and X-MAC protocol adopt Low Power Listening (LPL) technique with CSMA algorithm. All nodes in these protocols joining a network with independent duty cycle schedules without additional synchronization control packets. For this reason, asynchronous MAC protocol improve energy efficiency. In this study, a low-power MAC protocol which is based on X-MAC protocol for wireless sensor network is proposed for better energy efficiency. For this protocol, we suggest preamble numbering, and virtual-synchronization technique between sender and receive node. Using TelosB mote for evaluate energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1066-1080
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• 2003

In this paper a scalable QoS routing scheme for distributed multimedia applications in a hierarchical wide area network is proposed. The problem of QoS routing is formulated as a multicriteria shortest path problem, known as NP-complete. The proposed hierarchical routing scheme consists of two phases. In Phase 1, every border node periodically pre-computes the QoS distance for the paths between every pair of border nodes in any level of domain hierarchy. This phase is independet of the QoS request from an application. In Phase II, distributed graph construction algorithm is performed to model the network as a graph by retrieving pre-computed QoS distances. The graph is constructed by the on-demand algorithm and contains a part of the network topology which is completely neglected or partially considered by existing routing schemes, thus maintaining more accurate topology information. By using retrieval approach rather than advertising one, no global QoS state information exchange among nodes is needed. In this Phase, distributed partition algorithm for QoS routing problem is also performed, thus eliminating virtual links on the hierarchically complete path.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1426-1433
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• 2015

CCTV-applied monitoring is an effective measure to suppress potential crimes and record objective relationship; however, there is no methodology that can quantitatively compare and assess the afore-mentioned effects. Thus, this study intended to construct the methodology and analysis application that can measure the changes in the space-corresponding performance of CCTVs depending on installation measures by using 3-dimenstional virtual simulation technology. For analysis, the raster-based Isovist theory was 3-dimensionally expanded and the amount of incident sight line to each point was accumulated. At the same time, the amount of overlapped monitoring in the CCTV cameras that were connected to each measurement node was accumulated for cross-analysis. By applying the examples and analyzing the results, it was possible to construct an analysis application in use of collision detection model and quantify the changes of monitoring performance depending on positioning alternative of the cameras. Moreover, it enabled intuitive review and supplementation by reproducing visible shadow areas in a graph.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.834-841
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• 2018

A power amplifier for subgigahertz short-range wireless communication using $0.18-{\mu}m$ CMOS technology is presented. It is designed as a differential structure to form easily a virtual ground node, to increase output power, and to design a cascode structure to prevent breakdown. The transistor gate width was determined to maximize the output power and power-added efficiency(PAE), and the balun was optimized through electromagnetic simulation to minimize the loss caused by the matching network. This power amplifier had a gain of more than 49.5 dB, a saturation power of 26.7 dBm, a peak PAE of 20.7 % in the frequency range of 860 to 960 MHz, and a chip size of $2.14mm^2$.

• The Journal of Korean Institute of Information Technology
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• v.17 no.4
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• pp.87-97
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• 2019

SRS was proposed for immediate processing of the meaning of sensor data on mobile devices independent from specific sensor networks and sensor type. However, each time new sensor data is received, sensor data inspection operations are performed repeatedly, and it cause resulting in low performance. App profile-based SRS has been proposed to resolve the problem. The app profile-based SRS has improved the SRS problem through the profile, but has been tested in a virtual simulation environment. After that the test was experimented in a real-time environment, but has not been tested with a variety of dynamic factors. Therefore, this paper experiment considering such as user mobility and sensor density in real-time environment. And this paper also evaluate performance of the App profile-based through analysis of the results of the experiment. As a result, app profile-based SRS is high influence by density and sensor type, and the number of sensor node is not influence.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.49-56
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• 2023

Currently, e-commerce is changing from a digital twin to a metaverse world. The metaverse world is an intermediate form between virtual and real worlds and is operated as a coin-based meta-commerce. In this meta-commerce world, blockchain-based NFT coins are used when trading items (contents). In this study, we studied how to issue a large number of NFT coins (certification) rather than issuing a single type of NFT. The research method was designed to produce content layer-based and automatically create the desired quantity using a mass NFT index and automatic generation method. In this study, a layer overlap method (background, body, etc.) was used with a Phyton-based program for mass minting. As a result, it can be used as a blockchain-based certificate that can prove a group of many people. In addition, the content created with the NFT index was registered on the NFT sales site to confirm its utilization and value.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.1
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• pp.10-19
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• 1986

This is the last part of the four-part describing the development of a packet-switched computer communication network named the KORNET. In this paper we describe the design and implementation of the packet assembler/dissassembler (PAD) protocol for the asynchronous channel service, and of the network management softwares. The line processing module-B(LPMB) system supporting the asynchronous line includes a PAD protocol, a packet mode DTE/DCE protocol converting to the X.25 protocol, and the asynchronous receiver/transmitter(ART) software. The network management software is operated in master central processing module(MCPM) which includes virtual circuit management (VCM) managing the user channel, the routing management and the high level protocol for communication between the network management center (NMC) and the network node processor(NNP). In this paper, the design, implementation and operation of the softwares for the above service functions will be described in detail.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.307-317
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• 2013

This study aims to investigate the research equipment establishing relationship by looking at research equipment information transfer that follows the network's structural and positional characteristics and the research institute's responsibilities to increase the possibility of research equipment usage by using the SNA(Social Network Analysis) method. Consequently, with the given structural characteristics of research institute, it can be concluded that because of its low density, it appears to be difficult to transfer research equipment information within the network. Government-funded research institutes that can effectively deliver research equipment information within the network system through comparison positional characteristics are ETRI, KITECH, KRICT, Sungkyungwan University, and Kyungbook National University. In addition, a virtualization node not only invigorates the network system but also acts as an intermediary factor to effectively deliver research equipment information. As results, there can be three conceivable alternatives to increase the possibility of research equipment usage. Those includes: 1. policy to encourage relationship building among research institutes 2. utilizing suitable institutes for effective delivery of research equipment information and lastly, 3. establishing a virtual intermediary institute for information sharing and utilization of isolated institutes' research equipments.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1285-1298
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• 2010

Since the TinyOS incorporating a non-preemptive task scheduling policy uses a FIFO (First-In First-Out) queue, a task with the highest priority cannot preempt a task with lower priority before the task with lower priority must run to completion. Therefore, the non-preemptive TinyOS cannot guarantee the completion of real-time user tasks within their deadlines. Additionally, the non-preemptive TinyOS needs to meet the deadlines of user tasks as well as those of TinyOS platform tasks called by user tasks in order to guarantee the deadlines of the real-time services requested by user tasks. In this paper, we present a group-based real-time scheduling technique that makes it possible to guarantee the deadlines of real-time user tasks in the TinyOS incorporating a non-preemptive task scheduling policy. The proposed technique groups together a given user task and TinyOS platform tasks called and activated by the user task, and then schedule them as a virtual big task. A case study shows that the proposed technique yields efficient performance in terms of guaranteeing the completion of user tasks within their deadlines and aiming to provide them with good average response time, while maintaining the compatibility of the existing non-preemptive TinyOS platform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.271-280
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• 2014

In wireless sensor networks, there have been two methods for sensing continuously moving object tracking: user-query based method and periodic report based method. Although the former method requires overhead for user query rather than the latter method, the former one is known as an energy-efficient method without transferring unnecessary information. In the former method, a virtual tree, consisting of sensor nodes, is exploited for the user querying and sensor reporting. The tree stores the information about mobile objects; the stored information is triggered to report by the user query. However, in case of fast moving object, the tracking accuracy reduces due to the time delay of end-to-end repeated query. To solve the problem, we propose a query relaying method reducing the time delay for mobile object tracking. In the proposed method, the nodes in the tree relay the query to the adjacent node according to the movement of mobile object tracking. Relaying the query message reduces the end-to-end querying time delay. Simulation results show that our method is superior to the existing ones in terms of tracking accuracy.