• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1796-1800
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• 1991

Picture Archiving and Communication Systems(PACS) provide an integration of digital imaging information in a hospital, which encompasses various imaging equipment, viewing workstations, database archive systems, and a high speed fiber optic network. One of the most important requirements for integration is the standardization of communication protocols to connect devices from different vendors. Since 1985, the ACR-NEMA standard provides a hardware interface, a set of software commands, and a consistent set of data formats for point-to-point interconnection of medical equipment. However, it has been shown to be inadequate for PACS networking environments, because of its point-to-point nature and its inflexibility to allow other services and protocols in the future. Based on previous experience of PACS developments in The University of Arizona, a new communication protocol for PACS networks has been suggested to the ACR-NEMA Working Group VI. The defined PACS protocol is intended to facilitate the development of PACS's capable of interfacing with other hospital information systems. Also, it is intended to allow the creation of diagnostic information data bases which can be interrogated by a variety of distributed devices. A particularly important goal is to support communications in a multivendor environment. The new protocol specifications are defined primarily as a combination of the International Organization for Standardization / Open Systems Interconnection (ISO/OSI) protocols and the data format portion of ACR-NEMA standard. This paper addresses the specification and implementation of the proposed PACS protocol into network node. The protocol specification, which covers Presentation, Session, Transport, and Network layers, is summarized briefly. The implementation has natural extentions to Global PACS environments. The protocol implementation is discussed based on our implementation efforts in the UNIX Operating System Environment. At the same time, results of performance evaluation are presented to demonstrate the implementation of defined protocol. The testing of performance analysis is performed on the PACS prototype node.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.75-86
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• 2014

Demand for the femtocell is largely credited to the surge in a more always best connected communication conscious public. 3GPP defines new architecture and security requirement for Release 9 to deal with femtocell, Home eNode B referred as HeNB. In this paper, we analyze the HeNB security with respect to mutual authentication, access control, and secure key agreement. Our analysis pointed out that a number of security vulnerabilities have still not been addressed and solved by 3GPP technical specification. These include eavesdropping, man-in-the-middle attack, compromising subscriber access list, and masquerading as valid HeNB. To the best of our knowledge, any related research studying HeNB security was not published before. Towards this end, this paper proposes an improved authentication and key agreement mechanism for HeNB which adopts proxy-signature and proxy-signed proxy-signature. Through our elaborate analysis, we conclude that the proposed not only prevents the various security threats but also accomplishes minimum distance from use-tolerable authentication delay.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.695-700
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• 2005

In the sensor network, a lot of sensor nodes are scattered sparsely and organizes a united communication network between each node. After that, environmental information around each sensor node are gathered and analyzed. Because each node operates under resource constraint, the efficiency and hardware specification of a node should be maximized. There exist technical constraints until now but recent technical progress in IC fabrication and wireless network enables to construct a tiny embedded system, which has the properties of low cost, low power consumption, multi functions. Wireless sensor network becomes a modern research field with technical improvements, is studied in numerous laboratories, and is called as diverse different project names - Wireless Integrated Network Sensors (WINS), Mobile Ad hoc NETwork (MANET), Ubiquitous Sensor Network (USN). TinyOS is one of leading project and is widely used. In this paper, we suggest a sensor network, which uses TinyOS platforms and aims for context awareness in a home environment.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.671-677
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• 2016

A Controller Area Network (CAN) is a serial communication protocol that is highly reliable and efficient in many aspects, such as wiring cost and space, system flexibility, and network maintenance. Therefore, it is chosen for the communication protocol between a single chip controller based on Field Programmable Gate Array (FPGA) and peripheral devices. In this paper, the design and implementation of CAN IP, which is written in VHSIC Hardware Description Language (VHDL), is presented. The implemented CAN IP is based on the CAN 2.0A specification. The CAN IP consists of three processes: clock generator, bit timing, and bit streaming. The clock generator process generates a time quantum clock. The bit timing process does synchronization, receives bits from the Rx port, and transmits bits to the Tx port. The bit streaming process generates a bit stream, which is made from a message received from a micro controller subsystem, receives a bit stream from the bit timing process, and handles errors depending on the state of the CAN node and CAN message fields. The implemented CAN IP is synthesized and downloaded into SmartFusion FPGA. Simulations using ModelSim and chip test results show that the implemented CAN IP conforms to the CAN 2.0A specification.

• Journal of Distribution Science
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• v.17 no.3
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• pp.85-95
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• 2019

Purpose - The existing marketing studies using Social Network Analysis have assumed that network structure variables are time-invariant. However, a node's network position can fluctuate considerably over time and the node's network structure can be changed dynamically. Hence, if such a dynamic structural network characteristics are not specified for virtual goods purchase model, estimated parameters can be biased. In this paper, by comparing a time-invariant network structure specification model(base model) and time-varying network specification model(proposed model), the authors intend to prove whether the proposed model is superior to the base model. In addition, the authors also intend to investigate whether coefficients of network structure variables are random over time. Research design, data, and methodology - The data of this study are obtained from a Korean social network provider. The authors construct a monthly panel data by calculating the raw data. To fit the panel data, the authors derive random effects panel tobit model and multi-level mixed effects model. Results - First, the proposed model is better than that of the base model in terms of performance. Second, except for constraint, multi-level mixed effects models with random coefficient of every network structure variable(in-degree, out-degree, in-closeness centrality, out-closeness centrality, clustering coefficient) perform better than not random coefficient specification model. Conclusion - The size and importance of virtual goods market has been dramatically increasing. Notwithstanding such a strategic importance of virtual goods, there is little research on social influential factors which impact the intention of virtual good purchase. Even studies which investigated social influence factors have assumed that social network structure variables are time-invariant. However, the authors show that network structure variables are time-variant and coefficients of network structure variables are random over time. Thus, virtual goods purchase model with dynamic network structure variables performs better than that with static network structure model. Hence, if marketing practitioners intend to use social influences to sell virtual goods in social media, they had better consider time-varying social influences of network members. In addition, this study can be also differentiated from other related researches using survey data in that this study deals with actual field data.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.127-136
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• 2009

Modeling and Simulation, especially in mobile ad hoc network(MANET), are the most effective way to analyze performance or optimize system parameters without establishing real network environment. Focusing mainly on overall network behaviors in MANET concerns dynamics of network transport operations, which can efficiently be characterized with event based system states rather than execution details of protocols. We thus consider the network as a discrete event system to analyze dynamics of network transport performance. Zeigler's set-theoretic DEVS(Discrete Event Systems Specification) formalism can support specification of a discrete event system in hierarchical, modular manner. The DEVSim++ simulation environment can not only provide a rigorous modeling methodology based on the DEVS formalism but also support modelers to develop discrete event models using the hierarchical composition methodology in object-orientation. This environment however hardly supports to specify connection paths of network nodes, which are continuously altered due to mobility of nodes. This paper proposes a DEVS-based modeling and simulation methodology of enabling node mobility, and develops DEVS models for the mobile ad hoc network. We also simulate developed models with the DEVSim++ engine to verify the proposal.

• Journal of Korea Multimedia Society
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• v.19 no.12
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• pp.2014-2023
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• 2016

Web presence is one of the key issues for extensive deployment of Internet-of-Things (IoT). An obstacle to overcome for Web presence is relatively low computing power of IoT devices. In this paper, we present implementation of an IoT platform based on Constrained Application Protocol (CoAP) which is a web transfer protocol proposed by Internet Engineering Task Force (IETF) for the low performance IoT devices such as Wireless Sensor Network (WSN) nodes and micro-controllers. To qualify the performance of CoAP-based IoT system for such an application as smart grid, we designed a test platform consisting of Raspberry Pi2, Kmote WSN node and a desktop PC. Using open source softwares, CoAP was implemented on top of the platform. Leveraging the GET command defined at CoAP specification, performance of the system was measured in terms of round-trip time (RTT) from web application to the Kmote sensor node. To investigate abnormal cases among the test results, hop-by-hop delays were measured to analyze resulting data. The average response time of CoAP-based communication except the abnormal data was reduced by 23% smaller than the previous research result.

• The Journal of Society for e-Business Studies
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• v.2 no.1
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• pp.21-37
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• 1997

As the complexity in design and manufacturing activities of distributed virtual enterprises rapidly increases, the issue of process management becomes more critical to shorten the time-to-market, reduce the manufacturing cost and improve the product quality. This paper proposes a unified framework to manage design and manufacturing processes in a distributed environment. We present a methodology which utilizes process flow graphs to depict the hierarchical structure of workflows and process grammars to represent various design processes and design tools. To implement the proposed concept, we develop a process management system which mainly consists of a cockpit and manager programs, and we finally address a preliminary implementation procedure based on the Object Modeling Technique. Since the proposed framework can be a formal approach to the process management by providing formalism, parallelism, reusability, and flexibility, it can be effectively applied to further application domains of distributed virtual enterprises.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.37-44
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• 2016

Optical fiber temperature sensing systems have incomparable advantages over traditional electrical-cable-based monitoring systems. However, the fiber optic interrogators and sensors have often been rejected as a temperature monitoring technology in real-world industrial applications because of high cost and over-specification. This study proposes a multiplexed fiber optic temperature monitoring sensor system using an economical Optical Time-Domain Reflectometer (OTDR) and Hard-Polymer-Clad Fiber (HPCF). HPCF is a special optical fiber in which a hard polymer cladding made of fluoroacrylate acts as a protective coating for an inner silica core. An OTDR is an optical loss measurement system that provides optical loss and event distance measurement in real time. A temperature sensor array with the five sensor nodes at 10-m interval was economically and quickly made by locally stripping HPCF clad through photo-thermal and photo-chemical processes using a continuous/pulse hybrid-mode laser. The exposed cores created backscattering signals in the OTDR attenuation trace. It was demonstrated that the backscattering peaks were independently sensitive to temperature variation. Since the 1.5-mm-long exposed core showed a 5-m-wide backscattering peak, the OTDR with a spatial resolution of 40 mm allows for making a sensor node at every 5 m for independent multiplexing. The performance of the sensor node included an operating range of up to $120^{\circ}C$, a resolution of $0.59^{\circ}C$, and a temperature sensitivity of $-0.00967dB/^{\circ}C$. Temperature monitoring errors in the environment tests stood at $0.76^{\circ}C$ and $0.36^{\circ}C$ under the temperature variation of the unstrapped fiber region and the vibration of the sensor node. The small sensitivities to the environment and the economic feasibility of the highly multiplexed HPCF temperature monitoring sensor system will be important advantages for use as system-integrated temperature sensors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1608-1615
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• 2010

In this paper, we proposed the method called "DoublePico"(Double Piconet) forovercoming low data transmission rate in a scatternet. This needs a new Ad-hoc network topology to transmit with high rate. Every node performs the function of the relay station. DoublePico has two bluetooth devices that should form two different poconets; every node can make a link between two different piconets. Two different piconets are linked in one node by the link with two bluetooth divices thereby forming the Ad-Hoc network. In this paper, we shows the method of DoublePico which supports about 457kbps of the maximum data transmission rate. This method supports a higher data transmission rate than the traditional bluetooth's Ad-Hoc topology by using analysis and comparison of existing algorithm of bluetooth specification and simulation results. Specifically, this paper focuses on the impact of intererence on the PER (Packet Error Rate), throughput performance, and the throughput improvement with SAW(Stop and Wait)-ARQ scheme in DoublePico.