• Journal of information and communication convergence engineering
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• 제17권4호
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• pp.255-260
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• 2019

A pendubot is a representative example of an underactuated system that has fewer actuators than the degree of freedom of the system. In this study, the characteristics of the pendubot are first reviewed; each part is then designed using Solidworks by dividing the pendubot into three parts: the base frame, first link frame, and second link frame. These three parts are then imported into the Simulink environment via a STEP file format, which is the standard protocol used in data exchange between CAD applications. A 3D model of the pendubot is then constructed using Simscape, and the usefulness of the 3D model is validated by a comparison with a dynamic equation derived using the Lagrangian formulation. A linearized model around an upright equilibrium position is finally obtained, and a sliding mode controller is designed based on the linear quadratic regulator. Simulation results showed that the designed controller effectively maintained upright balance of the pendubot in the presence of disturbance.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제39B권10호
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• pp.674-683
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• 2014

Multi-hop wireless networks has become common phenomenon according to a development of wireless communications and an increase of usage of wireless link. ARQ is one of the common protocols in link layer and can improve a link performance recovering packet loss in wireless link. However, ARQ cannot sufficient to assure a end-to-end performance because ARQ only manages the ARQ's own link. In this paper, we propose a new retransmission persistence for ARQ in multi-hop wireless network to satisfy the end-to-end performance. The proposed scheme can aware a bottleneck link according to the exchange of link information between ARQs and can support the end-to-end performance by managing a retransmission persistence. OPNET simulator is used to evaluate the performance of the proposed scheme and results show that proposed scheme can improve the end-to-end performance with satisfying a requirement of entire wireless section.

• International conference on construction engineering and project management
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.886-892
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• 2022

In construction projects, it is common to exchange documents using email because of convenience. In this study, a method extracting and organizing block information automatically based on email was developed. This method is composed of document exchange and archiving processes, which are difficult to manage and vulnerable to loss. Therefore, this study aims to develop a solution that can automatically link email and block information. The block data components are designed to derive from email exchange and user-additional input information. Also, automatically generating blocks process including extraction and conversion of information was proposed. This solution can lead to promote the convenience of project document management in terms of identifying the document flow and preventing loss of information.

• Journal of the Korean Society for Library and Information Science
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• 제34권2호
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• pp.211-232
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• 2000

The acquisition of foreign government documents by exchange or gift is problematic in the electronic government era because the pattern of distributing system is changed. The alternatives for the collection development are developing the meta-site and establishing the subject gateways for the foreign government information as the resource discovery tools. The anchor and link functions of the AltaVista are used to evaluate a meta-site. The Scout Project Isaac is suggested as the model of interoperating resource discovery services for the geographically distributed metadata databases.

• Journal of Korea Multimedia Society
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• 제21권8호
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• pp.897-908
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• 2018

In this paper, we propose a security framework for a cluster drones network using the MAVLink (Micro Air Vehicle Link) application protocol based on FANET (Flying Ad-hoc Network), which is composed of ad-hoc networks with multiple drones for IoT services such as remote sensing or disaster monitoring. Here, the drones belonging to the cluster construct a FANET network acting as WTRP (Wireless Token Ring Protocol) MAC protocol. Under this network environment, we propose an efficient algorithm applying the Lightweight Encryption Algorithm (LEA) to the CTR (Counter) operation mode of WPA2 (WiFi Protected Access 2) to encrypt the transmitted data through the MAVLink application. And we study how to apply LEA based on CBC (Cipher Block Chaining) operation mode used in WPA2 for message security tag generation. In addition, a modified Diffie-Hellman key exchange method is approached to generate a new key used for encryption and security tag generation. The proposed method and similar methods are compared and analyzed in terms of efficiency.

• Journal of the Korea Institute of Military Science and Technology
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• 제14권3호
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• pp.492-500
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• 2011

The airborne backbone network(ABN) provides communication transport services between airborne nodes, surface nodes and satellite nodes. Such ABN is generally constructed with wide-body and high-capacity planes such as AWACS, which can fly long-term along pre-defined flight paths. In this paper, we propose an efficient method to improve routing performances by reconfiguring routing path before link failure based on the prediction of link state with the information of pre-defined backbone nodes' trajectories. Since the proposed method does not need additional information exchange between airborne nodes in order to acknowledge the link failure, it can be effectively used for airborne backbone network with limited bandwidths.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제34권7B호
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• pp.694-702
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• 2009

Geographical routing protocol, where nodes only need local information exchange to make routing decisions, is a very efficient routing scheme for wireless sensor networks in scalability. However, pure geographical routing does not take account of wireless link condition. If wireless link condition is not considered, when the routing table is updated, the nodes with bad link conditions are updated in the routing table and can be chosen as the next hop. This brings out the retransmissions because of received packet's errors. Also, because of these retransmissions, additional power is consumed. In this paper, we propose geographical routing scheme considering wireless link condition, where reliable data transmission is made and the consumed energy is minimized.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제7권5호
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• pp.925-933
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• 2003

Network is expected to be developed into optical Internet network collected IP layer and optical layer, but GMPLS is risen at the transitional evolution stage because of the present technology level. GMPLS that MPLS is extended and generalized is able to support not only the packet switching device but also the devices which perform switching in time, wavelength, and space domain. To implement the common control plane to these various switching types, GMPLS extends the existing MPLS signaling and routing protocol. In this paper, we describe the overview of GMPLS technology, and then we will refer to the OSPF(Open Shortest Path First), which was used to exchange the status information of link, as the plan of routing extension to exchange the information of various link type, bandwidth, link protection type etc. And also, we describe the definition of new protocol, so called, LMP that is a signaling protocol for solving complex problem which manages hundreds and thousands of links between two nodes. And we will examine and analyze the plan of signaling protocol extension to apply signaling protocol RSVP-TE(Resource Reservation Protocol) for traffic engineering in MPLS to network, and the message objects and formats associated with modified RSVP.

• Journal of Advanced Marine Engineering and Technology
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• 제18권2호
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• pp.104-112
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• 1994

The scavenging efficiency has a great influence on the performance of a diesel engine, especially slow two-stroke diesel engines which are usually used as a marine propulsion power plant. And this is greatly affected by the conditions in the cylinder, scavenging manifold and exhaust manifold during the gas exchange process. There are many factors to affect on the scavenging efficiency and these factors interact each other very complicatedly. Therefore the simulation program of the gas exchange process is very useful to improve and predict the scavenging efficiency, due to the high costs associated with redesign and testing. In this paper, a three-zone scavenging model for two-stroke uniflow engines was developed to link a control-volume-type engine simulation program for performance prediction of long-stroke marine engines. In this model it was attempted to simulate the three different regions perceived to exist inside the cylinder during scavenging, namely the air, mixing and combystion products regions, by modeling each region as a seperate control volume. Finally the scavenging efficiency was compared with three type of scavenging modes, that is, pure displacement, partial mixing and prefect mixing.

• Journal of the Korea Institute of Military Science and Technology
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• 제13권5호
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• pp.861-868
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• 2010

As CAS, X-ATK, and INT models considered as the most typical Air-to-Ground operation models in ROKAF are mainly designed as the voice-centered system between aircraft and ground control facilities, it is critical to newly develop the Link-16 based model for the ROK-US combined operation between F-15K, AWACS, M-SAM, and KDX-III equipped with Link-16. Former studies had been limited to the CAS operation, and they had mainly focused on reducing the voice transmission time to exchange the information between each mission step with maintaining existing operation steps. Therefore, this paper makes up the weak point in former studies, thereby designing new Air-to-Ground operation model for CAS, X-ATK, INT mission using Enterprise Architecture OV6c, which enables both aircraft and ground control facilities or between aircraft to obtain the real-time information on the location, identification, armament and the real-time image data through the broadcasting function. Based on the analysis of new operation model, we come to a conclusion that by simultaneously exchanging the information on mission between nodes concerned through the broadcasting function of Link-16. It is possible to cut down superfluous steps among the mission steps, and to reduce the mission time. It is clear that it gives rise to improve the battle efficiency and the decision-making tempo as well as the battlefield situational awareness.