• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.147-151
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• 2014

With the advent of tiny and inexpensive computer systems like Raspberry Pi, it has become possible to construct an experimental environment of MANETs (Mobile Ad hoc Networks) at a relatively low cost. In this paper, we implement a node of MANETs with a Raspberry Pi equipped with two 802.11 wireless LAN cards and dynamic routing software running on it. In an outdoor MANETs environment with moving mobile nodes automatically rebuilding broken routes, we conducted a real-time video streaming experiment over the MANET. The video stream is transmitted from a node with a video camera installed on it to another node through the route established dynamically. Each node is equipped with a display device, with which the current status of the node can be checked out. We also implemented software that automatically collects data stored in each node and analyzes the performance of the MANETs. Through this experiment, we could evaluate the performance of realistic video streaming service in a MANETs environment.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.4
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• pp.391-398
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• 2010

Because mobile sensor network is different with the existing wireless sensor network with fixed nodes, it is more difficult to implement a positioning algorithm in mobile sensor network than in mobile sensor network. In case of fast moving node, a positioning algorithm may be not completed in a given time. In this paper we present the positioning algorithm that improves performance and can complete a computation in time on mobile sensor network.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.74-86
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• 1997

With continued miniaturization and development of new devices, the highly nonuniform oxidation of three-dimensional non-planar silicon structures plays an increasingly important role. In this paper, the three-dimensional finite element numerical simulator. Grwoth of oxide is a coupled process of diffusion of oxidant and deformation of oxide. Because boundaries of oxide are moved in each time step and LOCOS structure is formed three-dimensional shape of sruface, it is necessary to develope an efficient node control algorithm that can locally generate and eliminate the node. Therefore we have developed the optimized three-dimensional mesh generator which is cpable of refining and eliminating the meshes at the moving boundary of oxide, and hve developed three-dimensional finite element oxidation solver.

• Annual Conference of KIPS
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• 2004.05a
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• pp.1417-1420
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• 2004

The combination of Fast-Handoff and Hierarchical Mobile IPv6 (F-HMIPv6) allows the anticipation of the layer3 handoff such that data traffic can be efficiently redirected to the mobile node's new location before it moves there. However, after moving to the new Access Router (NAR), if the mobile node (MN) sends the Local Binding Update (LBU) to the Mobility Anchor Point (MAP) before receiving all of the buffered packet from the NAR, the MN may receive the general packet from the MAP. That is, the MN may simultaneously receive two types of packet which has different sequence number. These cause the confusion in packet order, and the MN sends the dup ack for the packet retransmission to the CN. It results in the degradation of the TCP performance. Therefore, we propose the scheme for minimizing the out-of-sequence packet in F-HMIPv6.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.67-72
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• 2021

MANET(Mobile Ad Hoc Network) is the structure in which a source node communicates with a destination node by establishing a route with neighbor nodes without using the existing wired or wireless network. Therefore, the routing protocol for MANET must correspond well to changes in the channel state of moving nodes, and should have simple operation, high reliability, and no routing loop. In this paper, the simulation was perform by using a traffic model with on/off two states provided by the NS-3 network simulator. Also, the duration of the ON state and the duration of the OFF state used the traffic where inter arrival time of data is irregular by generating random values with constant, exponential distribution, and Pareto distribution. The performance of the DSDV, OLSR, and AODV protocols was compare and analyzed using the generated traffic model.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.36-48
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• 2007

This paper proposed 3D keyframe animation using orientation interpolator. 3D keyframe animation consists of a number of transform nodes that have geometrical node of initial model and several interpolator nodes that represent the object moving. In the proposed algorithm, we randomly selects transform nodes with orientation interpolator node and performs to resample quaternion components for haying uniform key time. And then, watermark bits are embedded into quaternion components with large rotation angles. Experimental results verified that the watermark embedded by the proposed algorithm had good robustness against geometrical attacks and timeline attacks and also PSNR of keyvalue in orientation interpolator node is above 42dB.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.237-242
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• 2005

In this paper, a fast handoff algorithm between PDSNs in 3GPPx network for a mobile node, is proposed. It introduces a method by which handoff can be performed without reestablishing PPP connection that may occur in the process of performing handoff between PDSNs. When the PDSN recognizes the mobile node moving into its coverage area, it can quickly establish a communication channel with the mobile node based on the already received subscriber information. As a result, handoff is performed without reestablishing PPP. Accordingly, handoff between PDSNs can be performed faster, removing time needed for establishing a PPP session with a terminal and for terminating a previously set up PPP session.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.129-135
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• 2010

This paper suggests a multipath establishing scheme for ad hoc networks. Data paths are established by on-demand manner. Multipath are made as a sequence of route control message exchange at route setup process. Multipath can be used as a backup path or load balancing for data exchange. Proposed scheme uses a one-hop pre-search scheme for establishing multipath between source and destination. When a node selects a next node for route reply, the node finds optimal route by exchanging route information with neighbor nodes. Simulation results show that the proposed multipath scheme has better split characteristics among multipath and higher route survivability at the environment where nodes are moving.

• Korean Journal of Remote Sensing
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• v.23 no.5
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• pp.465-471
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• 2007

Many hospitals have been considering new technology such as wireless sensor network(WSN). The technology can be used to track the location of medical devices needed for inspections or repairs, and it can also be used to detect of a theft of an asset. In an asset-tracking system using WSN, acquiring the location of moving sensor nodes inherently introduces uncertainty in location determination. In fact, the sensor nodes attached to an asset are prone to failure from lack of energy or from physical destruction. Therefore, even if the asset is located within the predetermined area, the asset-tracking application could "misunderstand" that an asset has escaped from the area. This paper classifies the causes of such unexpected situations into the following five cases: 1) an asset has actually escaped from a predetermined area; 2) a sensor node was broken; 3) the battery for the sensor node was totally discharged; 4) an asset went into a shadow area; 5) a sensor node was stolen. We implemented and installed our asset-tracking system in a hospital and continuously monitored the status of assets such as ventilators, syringe pumps, wheel chairs and IV poles. Based on this real experience, we suggest how to differentiate each case of location uncertainty and propose possible solutions to prevent them.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.2-7
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• 2008

A highly efficient moving least squares finite difference method (MLS FDM) for heat transfer analysis of composite material with interface. In the MLS FDM, governing differential equations are directly discretized at each node. No grid structure is required in the solution procedure. The discretization of governing equations are done by Taylor expansion based on moving least squares method. A wedge function is designed for the modeling of the derivative jump across the interface. Numerical examples showed that the numerical scheme shows very good computational efficiency together with high aocuracy so that the scheme for heat transfer problem with different heat conductivities was successfully verified.