• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.415-418
• /
• 2018

To reduce the flooding overhead of typical AODV, we propose a local flooding initiated by a destination. The proposed routing protocol determines the one-hop neighbor nodes around the shortest path between source and destination by overhearing, and periodically generate flooding at the destination to cope with topology changes. This flooding process involves only one-hop neighbor nodes around the shortest path for reducing the flooding overhead and forms multiple alternate paths around the shortest path. This makes it possible to seamlessly route to the newest shortest path around when the current routing path is disconnected.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37B no.9
• /
• pp.767-777
• /
• 2012

Topology control increases channel efficiency by controlling transmission power of a node, and as a result, network lifetime and throughput are increased. However, reducing transmission range causes a network connectivity problem, especially in mobile networks. When a network loses connectivity, the network topology should be re-configured. However, topology re-configuration consumes lots of energy because every node need to collect neighbor information. As a result, network lifetime may decrease, even though topology control is being used to prolong the network lifetime. Therefore, network connectivity time needs to be increased to expend network lifetime in mobile networks. In this paper, we propose an Adaptive-Redundant Transmission Range (A-RTR) algorithm to address this need. A-RTR uses a redundant transmission range considering a node status and flexibly changes a node's transmission range after a topology control is performed.

• The KIPS Transactions:PartA
• /
• v.8A no.2
• /
• pp.157-166
• /
• 2001

A simulation package has been developed as an event-driven system that can handle the hardware configuration of STC104 and algorithm proposed in the sister paper of ‘Study on High Speed Routers(II).’After various STC104 topology of meshes, torus, and hypercubes are constructed using up to 512 switches, the performance of each topology has been analyzed under different message generation rate in terms of throughputs, latency, and packet blocking time. Modified multicast algorithms for STC104 have been proposed for STC104 after U-mesh and U-torus in order to overcome the multicasting difficulty because of the point-to-point communication method found in STC104. The performance of the multicast algorithms have been analyzed over meshes and torus configuration. Throughput gets higher in the order of mesh, torus, and hypercube. Throughput difference among topology were distinctive in the zone of high message generation rate. Latency and blocking time increased in the order of hypercube, torus, and mesh. U-mesh and U-torus of software multicast showed similar throughput, however, U-mesh peformed slightly better result. These algorithms showed eight to ten times better results compared to individual message pass for 90 destination nodes. Multi-link environment also showed better performance than single-link environment because multi-link network used the extra links for communication.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.2C
• /
• pp.283-290
• /
• 2004

With the development of Web technologies, the demand for multimedia contents and network bandwidth is increasing explosively. In this situation, Caching, P2P and CDN are using for fast transmission with low traffic. In this research, we designed and implemented a redirection system for best replica selection where contents are distributed to multiple replicated web servers. This redirection system selects a close and least loaded replica and redirect a client's request to the replica. As a result, this system improved user-perceived performance. It is expected that this redirection system will contribute to the faster and more stable transmission of massive multimedia contents.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.6
• /
• pp.233-241
• /
• 2008

The overlay multicast that has been recently presented as an alternative for the IP multicast needs scheduling method that can apply the system resource and the network bandwidth for the many users. We propose a efficient overlay multicasting network policy for multimedia services with composite stream service topology. And in order to evaluate the ability of the proposed scheme's performance, We test the performance of multi_casting nodes with RTT values, the bandwidth attrition rate for building the network topology and MOR effects with Overcast[5] The result of simulation shows improves about $8{\sim}20%$ of performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.499-502
• /
• 2018

We propose a wireless-powered multihop transmission scheme using inter-node cooperation in a linear network topology. The proposed protocol determines the energy transfer time for each node to make the lifetime of the each node be equal in order to maximize the lifetime of the multihop path. To make the lifetime of each node the same, we apply the flocking algorithm which imitates the behavior of a bird flock flying at the same velocity, so that the lifetime of the nodes is averaged locally. Simulation results show that the proposed algorithm can maximize the lifetime of the multihop path by making all nodes have the same lifetime.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.467-469
• /
• 2018

Tactical wireless communications often suffer from communication problems such as channel interference and communication disconnection due to the variability of the network topology and poor communication environment. Therefore, it is very important to overcome the problem of communication failure of the wireless communication network caused by the poor tactical environment and to improve the survivability. This paper describes the automatic control methodology of wireless communication equipment to identify and distinguish the situation of communication failure without user intervention and to implement more effective solution.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2007.10a
• /
• pp.247-256
• /
• 2007

Accessibility is a field of study that has primarily been applied to urban or transportation problems two dimensionally. However, in large complex buildings as shopping centers or hospitals, inter-spatial accessibility among compartments has to be taken into account such as in building layouts or evacuation planning. This study expands space syntax theory, one of accessibility-related methodologies used for computing connectivity in urban or architectural spaces, into 3D indoor spaces. Although space syntax is basically a topology-based theory that does not consider general costs such as distance or time, this study suggests modification that incorporates different types of impedances in moving between places including distances, turns and transfers between floors. The proposed method is applied to a 3D campus building model in computing and displaying the accessibility to exit doors or cohesive accessibility among similar functions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.6C
• /
• pp.571-580
• /
• 2002

In this paper, we relatively differentiate maximum delay for each Assured Service subclass in Differentiated Services by allocating bandwidth to each subclass differently. To maximize the throughput for the In-profile traffic and the link utilization, we propose a Cofiguration method of RIO and the admission control criterion based on the buffer size determined by the network topology and the ratio of bandwidth allocated to each subclass. Simulation results show that the proposed method can calculate the capacity to guarantee the QoS for the Assured Service and maximize the throughput for the In-profile traffic and the link utilization by applying the RIO parameter values set through the proposed configuration method.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.9
• /
• pp.495-502
• /
• 2004

A rapid growth of the Internet user and rich media content cause an excessive server load and high network traffic, and thus it decreases the quality of service. A solution to this problem is to distribute the content on multiple replicated servers. However, in this circumstance, clients face additional task of selecting the best server to provide proper so${\gamma}$vice which clients request. This paper is intended to propose an adaptive server selection mechanism for a client request based on distance and server load. This will offer a fast and scalable service in response to the increase of massive and realtime multimedia content and contribute to floating a new business model of digital content service.