• The KIPS Transactions:PartC
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• v.10C no.6
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• pp.711-716
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• 2003

We propose a new Interet time synchronization model using danamic linear model and introduce the characteristics of internet transmission delays. SNTP(Simple Network Time Protocol) has been widely used as a time synchronization method on the Internet. While SNTP provides a very simple usage, SNTP may not provide the stable services, since SNTP does not consider the several essential error factors. In order to overcome the instabitily of SNTP, we analyze the process of time estimation of SNTP and find the difference between forward transmission delay and backward transmission delay operates the main error on the estimation of an time offset.

• Proceedings of the KAIS Fall Conference
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• 2003.11a
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• pp.197-206
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• 2003

With the growing usage of the networks, the world-wide Internet has become the main means to exchange data and carry out transactions. It has also become the main means to attack hosts. To solve the security problems which occur in the network such as Internet, we import software products of network security elements like an IDS (Intrusion Detection System) and a firewall. In this paper, we have designed and constructed the General Simulation Environment of Network Security model composed of multiple IDSes and a firewall which coordinate by CNP (Contract Net Protocol) for the effective detection of the intrusion. The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. Command console in the CNP is a manager who controls tie execution of agents or a contractee, who performs intrusion detection. In the Network Security model, each model of simulation environment is hierarchically designed by DEVS (Discrete EVent system Specification) formalism. The purpose of this simulation is to evaluate the characteristics and performance of CNP architecture with rete pattern matching algorithm and the application of rete pattern matching algorithm for the speeding up the inference cycle phases of the intrusion detection expert system.

• Journal of Digital Convergence
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• v.10 no.6
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• pp.225-230
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• 2012

When a car accident happened, the accident vehicle should broadcast a safe message to its neighbors in multi-hop. However, the pure flooding is difficult to protect a chain-reaction collision because of the frequent collision and the communication delay. To solve this problem, we proposes a back-off algorithm applied to the estimation of the neighbor node count using the t-distribution. And we proposes a MAC protocol preventing the communication delay by separating the neighbor's count collection channel and data channel. As a result, we show the frame reception success rate of our protocol improved more 10% than the previous protocol.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.4
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• pp.41-49
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• 2008

Sensor networks are often deployed in unattended environments, thus leaving these networks vulnerable to false data injection attacks in which an adversary injects forged reports into the network through compromised nodes. Such attacks by compromised sensors can cause not only false alarms but also the depletion of the finite amount of energy in a battery powered network. In order to reduce damage from these attacks, several security solutions have been proposed. Researchers have also proposed some techniques to increase the energy-efficiency of such security solutions. In this paper, we propose a CH(Cluster Header) selection algorithm to choose low power delivery method in sensor networks. The CNP(Contract Net Protocol), which is an approach to solve distribution problems, is applied to choose CHs for event sensing. As a result of employing CNP, the proposed method can prevent dropping of sensing reports with an insufficient number of message authentication codes during the forwarding process, and is efficient in terms of energy saving.

• Journal of the Korean Society for information Management
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• v.14 no.1
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• pp.183-206
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• 1997

The information Retrieval Protocol, Z39.50 is applied to the shared cataloging gateway. The history and functions of the Z39.50 are reviewed and the characteristics and the database update service of Z39.50 are taken into account in the notion of the shared cataloging. And for the test, one of the domestic on-line shared cataloging systems is adopted and newly remodelled using Z39.50 protocol. Two kinds of Z39.50 shared cataloging gateway models (th centralized shared cataloging gateway model and the distributed shared cataloging gateway model) are operated in Web server.

• Journal of Astronomy and Space Sciences
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• v.28 no.3
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• pp.241-252
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• 2011

A simulated network protocol provides the capability of distributed simulation to a generic simulator. Through this, full coverage of management of data and service handling among separated simulators is achieved. The distributed simulation environment is much more conducive to handling simulation load balancing and hazard treatment than a standalone computer. According to the simulated network protocol, one simulator takes on the role of server and the other simulators take on the role of client, and client is controlled by server. The purpose of the simulated network protocol is to seamlessly connect multiple simulator instances into a single simulation environment. This paper presents the development of a simulated network (simNetwork) that provides the capability of distributed simulation to a generic simulator (GenSim), which is a software simulator of satellites that has been developed by the Korea Aerospace Research Institute since 2010, to use as a flight software validation bench for future satellite development.

• Journal of the Korea Computer Industry Society
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• v.5 no.2
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• pp.251-260
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• 2004

As the importance and the need for network security is increased, many organization uses the various security systems. They enable to construct the consistent integrated security environment by sharing the vulnerable information among firewall, intrusion detection system, and vulnerable scanner. We construct the integrated security simulation environment that can be used by some security system model. In this paper, we have designed and constructed the general simulation environment of network security model composed of multiple IDSs agent and a firewall agent which coordinate by CNP (Contract Net Protocol). The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. We compare the selection algorithm in the CPN with the Fuzzy Controller for the effective method to select the agents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1244-1255
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• 1994

The wireless-LAN(Local Area Network), which is emerged as a solution to cable problem and increasing requirement for communication network, has a several problem when it transmit information MAN protocol by used wired-LAN`s MAC protocol. Media Access protocol in Wireless-LAN has great effect on system performance and much studies are processing now. The PRMA(Packet Reservation Multiple Aeecss) of reservation method has a disadvantage that the system performance was degraded become of delay time in the reservation step as a resulting of collision. In this paper, using the TDD(Time Division Duplex) method amd modified PRMA method wireless-LAN modelled to overcome disadvantage, that id delay time due to collision in reservation step. The performance evaluation fo the model was done using M/M/1//M process model and this was simulation using SLAM.

• The KIPS Transactions:PartA
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• v.10A no.3
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• pp.231-238
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• 2003

Distributed systems present new system architecture for solving interoperability problem in heterogeneous system. This paper presents CORBA Inter-ORB protocol model based on shared memory to support communication software through analysis of existing CORBA IIOP protocol performance and Inter-Process Communication techniques. In the same host environment, proposed model applied standard CORBA mechanism to minimize message transfer overhead can develop software independently to hardware architecture of target communication system. This communication software that has flexibility and extensibility can improve productivity, duality and reusability of software.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1022-1025
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• 2008

Session Initiation Protocol (SIP) has become the call control protocol of choice for Voice over IP (VoIP) networks because of its open and extensible nature. However, the integrity of call signaling between sites is of utmost importance, and SIP is vulnerable to attackers when left unprotected. Currently a herby-hop security model is prevalent, wherein intermediaries forward a request towards the destination user agent sewer (UAS) without a user agent client (UAC) knowing whether or not the intermediary behaved in a trusted manner. This paper presents an integrated security model for SIP-based VoIP network by combining hop-by-hop security and end-to-end security.