• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.40-49
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• 2006

As a promising integrated circuit, wireless communication and micro-computing technology, the technology of sensor network that will lead the information technology industries of the next generation and realize the ubiquitous computing is one of the most active research topics and its research activities are also making today. From now on, each node, the network formation, and even the sensor network itself will interact with the generic network and evolve dynamically according to environmental changes in a process of continual creation and extinction. Therefore, address-internetworking between sensor network and generic network which are used different address mechanism is required. In this paper, we propose a static address-internetworking scheme for interactive networking between a sensor network and the Internet. The proposed scheme that possess a gateway approach to perform the protocol translation from one protocol to another, an overlay approach to constructs an overlay network on the WSNs and enables static internetworking between a sensor network address scheme based on Zigbee and the Internet address scheme based on the Internet Protocol. In addition, we verify the proposed scheme by an interconnection experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1646-1652
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• 2010

The communication in wireless sensor network is divided into several layers, because of each of them do their role, the wireless communication is possible, the MAC (Medium Access Control) layer of the one of sensor network communications layer is used to the data errors, control flow, and manage resources. Using MAC Protocol, it ensures the communication between sensor node. In this paper, highlighted the energy efficiency of the S-MAC, T-MAC protocol it emphasized the efficiency of energy by lessening the woken time of all nods effectively, transmitting and receiving the control packet on only necessary nods through use of a method that RTS packet is added to SYNC packet and making other nods sleep. On sending SYNC+RTS packet and receiving the packet, nod noticed that it wasn't necessary to be awaked on this period, would be in Sleep mode, demonstrated mathematically that energy is more effective than existing protocol, and simulated with MATLAB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.453-461
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• 2010

A critical issue in wireless sensor networks is an energy-efficiency since the sensor batteries have limited energy power and, in most cases, are not rechargeable. The most practical manner relate to this issue is to use a node wake-up scheduling protocol that some sensor nodes stay active to provide sensing service, while the others are inactive for conserving their energy. Especially, CTC (Connected Target Coverage) problem has been considered as a representative energy-efficiency problem considering connectivity as well as target coverage. In this paper, we propose a new energy consumption model considering multiple-targets and create a new problem, CMTC (Connected Multiple-Target Coverage) problem, of which objective is to maximize the network lifetime based on the energy consumption model. Also, we present SPT (Shortest Path based on Targets)-Greedy algorithm to solve the problem. Our simulation results show that SPT-Greedy algorithm performs much better than previous algorithm in terms of the network lifetime.

• Journal of Digital Contents Society
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• v.18 no.4
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• pp.753-760
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• 2017

In this paper, we propose a new method to improve the performance of a Quorum-based NDP (Neighbor Discovery Protocol) in heterogeneous wireless sensor networks. It creates a new set of discovery schedules by combining two different Quorum-based matrices. The original Quorum-based schedule guarantees only two overlapping active slots with a cycle, but the newly created matrix greatly increases the chance of neighbor discovery. Therefore, although the size of the combined matrix of the proposed method increases, the number of discovery chances with neighboring nodes considerably increases, and the new approach is superior to the original Quorum-based neighbor node discovery protocol. In this study, we compares the performance of the proposed method to the Quorum-based protocols such as SearchLight and Hedis using TOSSIM. We assume all sensor nodes operates in a different duty cycle in the experiment. The experimental results show that the proposed algorithm is superior to other Quorum-based methods.

• The Journal of the Korean dental association
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• v.55 no.11
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• pp.789-799
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• 2017

Ultrasound images are noninvasive, can be observed in real time, have no radiation exposure, do not cause pain, and are not restricted in use depending on the patient's prosthetic implant or medical condition. Since the use of ultrasound in the dental field was first applied for tooth preparation in 1957, the use of diagnostic ultrasound for the first time in 1963 has been reported. Currently, it is used in the diagnosis of soft tissue lesions such as malignant tumor or salivary gland disease, fine needle aspiration test, temporomandibular joint disease, lymph node metastasis, measurement of muscle thickness and inflammatory diseases, differentiation of periapical cyst and granulation tissue, measurement of periodontal tissue thickness. The ultrasound image can be visualized in real time. The clinician can explain the structure to the patient while consulting the patient and consult the patient. When injecting the drug into a specific site or aspirating a specific site or substance, So that it can be confirmed and practiced. Recently, ultrasonic equipment specialized in the dental field has been developed and marketed, and it is expected that the use of ultrasonic waves will become active in the dentistry. In the future, development of popular equipment with size and frequency suitable for dental diagnosis and various researches on maxillofacial ultrasonic anatomy. If clinical studies are continuously carried out to demonstrate efficacy, ultrasound is expected to aid in accurate diagnosis and treatment throughout the dentistry.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.179-189
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• 2000

This study is tried to organic combination in implementing the suitability analysis of urban landuse between GSIS and ANN(Artificial Neural Network). ANN has merit that can decide rationally connectivity weights among neural network nodes through procedure of learning. It is estimated to be possible that replacing the weight among factors needed in spatial analysis of the connectivity weight on neural network. This study is composed of two kinds of neural networks to be executed. First neural network was used in the suitability analysis of landuse and second one was oriented to analyze of optimum landuse pattern. These neural networks were learned with back-propagation algorithm using the steepest gradient which is embodied by C++ program and used sigmoid function as a active function. Analysis results show landuse suitability map and optimum landuse pattern of study area consisted of residental, commercial. industrial and green zone in present zoning system. Each result map was written by the Grid format of Arc/Info. Also, suitability area presented in the suitability map and optimum landuse pattern show distribution pattern consistent with theroretical concept or urban landuse plan in aspect of location and space structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.304-310
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• 2006

This paper evaluates the performance of three types of data delivery mechanisms in clustered sensor networks, as a basic research to develop an energy efficient topology management scheme. In the first mechanism, one node per cluster(clusterhead) turns on its radio(or wakes up) to transmit and receive RTS/CTS/DATA/ACK messages, but in the second one, k nodes per cluster wake up and participate in the message exchange. In the last mechanism, clusterheads turn on the radio to exchange RTS/CTS messages, and if a clusterhead receives RTS containing its cluster m as a destination, it makes k nodes in the cluster hun on the radio to receive DATA and transmit ACK. Through simulation, we show the energy consumption of the three types of data delivery mechanisms as functions of the number of active nodes per cluster, offered load, and packet loss probability.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.395-400
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• 2005

The IEEE 802.11b WLAN supports multiple transmission rates and the rate is chosen in an adaptive manner by an auto rate control algorithm. This auto rate control algorithm deeply affects the total system performance of the IEEE 802.11b WLAN. In this paper, we examine the WLAN performance with regard to the auto rate control algorithm especially the ARF scheme. The experimental results indicate that the ARF scheme works well in the face of signal noise due to node location. However, the ARF scheme severely degrades system performance when multiple nodes contend to obtain the wireless channel and the packet is lost due to signal collision. In addition, TCP prevent the performance degradation due to ARF scheme by retaining number of active nodes. However, some applications, such as transporting multimedia data, adopt the UDP. Therefore, the TCP cannot be an optimal solution for all WLAN applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.538-541
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• 2006

Recently researches of P2P media streaming have been actively published, but the research what kind of P2P overlay networks are better to delivering media data has not been attended. This paper designs a P2P streaming media system model. In this system, we constructs a Half-Structure P2P overlay protocol based on node's capability as the infrastructure of streaming application, which utilizes the heterogeneity of the nodes to maintain topology, presents a active contents diffusing algorithm and Two-stage search algorithm, make it possible for nodes in P2P system to collect information according their capacity and reduces the number of forwarding packet compared with flooding. Also, we give an optimal scheme to scheduling media data.

• KNOM Review
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• v.24 no.1
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• pp.1-12
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• 2021

VM (Virtual Machine) live migration is a server virtualization technique for deploying a running VM to another server node while minimizing downtime of a service the VM provides. Currently, in cloud data centers, VM live migration is widely used to apply load balancing on CPU workload and network traffic, to reduce electricity consumption by consolidating active VMs into specific location groups of servers, and to provide uninterrupted service during the maintenance of hardware and software update on servers. It is critical to use VMlive migration as a prevention or mitigation measure for possible failure when its indications are detected or predicted. In this paper, we propose two VNF live migration methods; one for predictive load balancing and the other for a proactive measure in failure. Both need machine learning models that learn periodic monitoring data of resource usage and logs from servers and VMs/VNFs. We apply the second method to a vEPC (Virtual Evolved Pakcet Core) failure scenario to provide a detailed case study.