• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.471-478
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• 2003

Traditionally,, analysis, simulation and measurement have all been used to evaluate the performance of network protocols and functional entities that support mobile wireless service. Simulation methods are useful for testing the complex systems which have the very complicate interactions between components. To develop a mobile call simulator which is used to examine, validate, and predict the performance of mobile wireless call procedures must have the teletraffic model, which is to describe the mobile communication environments. Mobile teletraffic model is consists of 2 sub-models, traffic source and network traffic model. In this paper, we analyzed the network traffic data which are gathered from selected Base Stations (BSs) to define the mobile teletraffic model. We defined 4 types of cell location-Residential, Commercial, Industrial, and Afforest zone. We selected some Base Stations (BSs) which are represented cell location types in Seoul city, and gathered real data from them And then, we present the call rate per hour, cail distribution pattern per day, busy hours, loose hours, the maximum number of call, and the minimum number of calls based on defined cell location types. Those parameters are very important to test the mobile communication system´s performance and reliability and are very useful for defining the mobile network traffic model or for working the existed mobile simulation programs as input parameters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2593-2600
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• 2010

A growth of mobile and wireless networking technologies have enabled mobile ad hoc networks applicable to a wide range of areas. This paper analyzes dynamics of network transport performance with respect to dynamics of network states especially for the mobile ad hoc networks called MANET. The edge cost based modeling methodology is adopted for the analysis, which can express well the characteristics of MANET. In this methodology the network state at arbitrary time can be specified as one of four edge states. We extracts ten target network scenarios for the simulation analysis by employing not only the Real Edge/Infinity Edge concept but also interworking functionality between different transport protocols. Then we could acquire from simulation of them with the DEVSim++ engine that the more sorts of transport protocols and the more number of interworking nodes are included in the network, the more contribution is for improving network transport performance.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1916-1917
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• 2011

A development of a new moving obstacle avoidance algorithm using a delay-time Compensation for a network-based autonomous mobile robot is proposed in this paper. The moving obstacle avoidance algorithm is based on a Kalman filter through moving obstacle estimation and a Bezier curve for path generation. And, the network-based mobile robot, that is a unified system composed of distributed environmental sensors, mobile actuators, and controller, is compensated by a network delay compensation algorithm for degradation performance by network delay. The network delay compensation method by a sensor fusion using the Kalman filter is proposed for the localization of the robot to compensate both the delay of readings of an odometry and the delay of reading of environmental sensors. Through some simulation tests, the performance enhancement of the proposed algorithm in the viewpoint of efficient path generation and accurate goal point is shown here.

• Journal of Communications and Networks
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• v.17 no.2
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• pp.110-117
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• 2015

In mobile social network, it is a critical challenge to select an optimal set of devices to supply high quality service constantly under dynamic network topology and the limit of device capacity in mobile ad-hoc network (MANET). In this paper, a multi-devices composition and maintenance problem is proposed with ubiquitous service model and network model. In addition, a multi-devices composition and maintenance approach with dynamic planning is proposed to deal with this problem, consisting of service discovery, service composition, service monitor and service recover. At last, the simulation is implemented with OPNET and MATLAB and the result shows this mechanism is better applied to support complex ubiquitous service.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.8
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• pp.471-481
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• 2003

The acts of biological immune system are similar to the navigation for autonomous mobile robots under dynamically changing environments. In recent years, many researchers have studied navigation algorithms using artificial immune networks. Conventional artificial immune algorithms consist of an obstacle-avoidance behavior and a goal-reaching behavior. To select a proper action, the navigation algorithm should combine the obstacle-avoidance behavior with the goal-reaching behavior. In this paper, the neural network is employed to combine the behaviors. The neural network is trained with the surrounding information. the outputs of the neural network are proper combinational weights of the behaviors in real-time. Also, a velocity control algorithm is constructed with the artificial immune network. Through a simulation study and experimental results for a autonomous mobile robot, we have shown the validity of the proposed navigation algorithm.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.269-273
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• 2000

This paper proposes a algorithm for several mobile robots navigation. There are three parts in this algorithm. First part generates robots turning angle and moving distance for goal approaching, sencond part generates robots avoiding angle and avoiding distance for static obstacles or other robots and third part adjust between robots moving distance and avoiding distance. Most simulation results of this algorithm are very effective for several mobile robots traveling in unknown field.

• Journal of Korea Multimedia Society
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• v.11 no.11
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• pp.1525-1535
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• 2008

High Altitude Platform (HAP) based networks deploy network infrastructures of Mobile Base Station (MBS) in a form of Unmanned Aerial Vehicle (UAV) at stratosphere in order to build network configuration. The ultimate goal of HAP based network is a wireless network service for wide area by deploying multiple MBS for such area. In this paper we assume multiple UAVs over designated area and solve the MBS placement and coverage problem by clustering the mobile ground nodes. For this study we assumed area around Cheju island and nearby naval area where multiple mobile and fixed nodes are deployed and requires HAP based networking service. By simulation, visual results of stratospheric MBS placement have been presented. These results include clustering, MBS placement and coverage as well as dynamic reclustering according to the movement of mobile ground nodes.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3332-3339
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• 1999

TCP protocol is originally designed for the wired network in which the packet loss in mostly caused the network congestion, and thus the performance of protocol can be decreased in mobile Internet environment due to the comparatively high error rate of wireless link. This paper analyzes the influence of retransmission interference that is a major factor to the TCP performance decrease. We first build a model in order to simulate the mobile Internet environment that includes the wireless network, and then we implement a program using PARSEC simulation language and finally executed the program. Based on the simulation results, we suggest a method that reduce the effect of the retransmission interference.

• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.131-134
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• 2008

A Mobile Ad hoc NETwork(MANET) is a system of wireless mobile nodes that dynamically self-organize in arbitrary and temporary network topologies. In the highly dynamic environment of MANET, energy efficiency is an important performance measure since it directly affects the network lifetime. The failure of energy severely impacts a communications system in crucial communications environments, such as disasters salvage. In this study, we propose a new packet switching routing that can increase the durability of the energy resource and therefore, the lifetime of the mobile nodes and MANET. The performance of the packet switching routing on the node-disjoint multipath and that of AODV are compared by NS2 simulation. The simulation results indicate that this new switching routing can extend the lifetime of a MANET.

• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.71-79
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• 1997

In this paper, operations system was designed for the centralization of data processing of various state information from the facilities of mobile communication network. And the system performance experimental system module was measured and analyzed from the designed experimental system module. The configuration of system design was presented with the centralized type to monite and control the facilities of mobile communication network in the central office. The communication process design of the internal system was implemented with the resource of message queue having a excellent transmission ability for processing of a great quantity of information in the inter-process communication among communication resources of UNIX system. The process with a server function from the internal communication processes was constructed with a single server or a double server according to the quantity of operations and implemented with the policy of the presented server. And then, we have measured performance elements in accordance with the change of input parameters from the designed experimental module : response time, waiting time, buffer length, the maximum quantity existing in message queue. And from these results, we have compared and analyzed the system state each server algorithm according to performance variations.