• Journal of information and communication convergence engineering
• /
• v.7 no.2
• /
• pp.119-124
• /
• 2009

In this paper, we propose a novel approach to estimating the real-time moving trajectory of an object is proposed in this paper. The object's position is obtained from the image data of a CCD camera, while a state estimator predicts the linear and angular velocities of the moving object. To overcome the uncertainties and noises residing in the input data, a Extended Kalman Filter(EKF) and neural networks are utilized cooperatively. Since the EKF needs to approximate a nonlinear system into a linear model in order to estimate the states, there still exist errors as well as uncertainties. To resolve this problem, in this approach the Kohonen networks, which have a high adaptability to the memory of the input-output relationship, are utilized for the nonlinear region. In addition to this, the Kohonen network, as a sort of neural network, can effectively adapt to the dynamic variations and become robust against noises. This approach is derived from the observation that the Kohonen network is a type of self-organized map and is spatially oriented, which makes it suitable for determining the trajectories of moving objects. The superiority of the proposed algorithm compared with the EKF is demonstrated through real experiments.

• Journal of information and communication convergence engineering
• /
• v.7 no.4
• /
• pp.475-479
• /
• 2009

In ad hoc network, the scarce energy management of the mobile devices has become a critical issue in order to extend the network lifetime. Current research activity for the Minimum Energy Multicast (MEM) problem has been focused on devising efficient centralized greedy algorithms for static ad hoc networks. In this paper, we consider mobile ad hoc networks(MANETs) that could provide the reliable monitoring and control of a variety of environments for remote place. Mobility of MANET would require the topology change frequently compared with a static network. To improve the routing protocol in MANET, energy efficient routing protocol would be required as well as considering the mobility would be needed. In this paper, we propose a new method, the CACH(Context-aware Clustering Hierarchy) algorithm, a hybrid and clustering-based protocol that could analyze the link cost from a source node to a destination node. The proposed analysis could help in defining the optimum depth of hierarchy architecture CACH utilize. The proposed CACH could use localized condition to enable adaptation and robustness for dynamic network topology protocol and this provide that our hierarchy to be resilient. As a result, our simulation results would show that CACH could find energy efficient depth of hierarchy of a cluster.

• The Journal of Korean Association of Computer Education
• /
• v.7 no.1
• /
• pp.45-53
• /
• 2004

Ad-Hoc network is wireless network architecture without infrastructure. We encounter new types of security problems in Ad-Hoc networks because such networks have little or no support from infrastructure. Thus, wireless communications need security mechanisms in order to guarantee the integrity and the privacy of the communication, as well as the authentication of the entities involved. Many practical systems have been proposed. The most familiar system is the Diffie-Hellman key distribution system. This algorithm allows the establishment of a cryptographic secret key between two entities. If more than two users want to compute a common key, then a group key agreement system is used. This paper discusses several group key agreement systems and presents two efficient fault tolerant methods to perform successful group key agreement.

• Convergence Security Journal
• /
• v.11 no.6
• /
• pp.37-44
• /
• 2011

VANET(Vehicular Ad-hoc Network) is a kind of ad hoc networks consist of intelligence vehicular ad nodes, and has become a hot emerging research project in many field. It provide traffic safety, cooperative driving and etc. but has also some security problems that can be occurred in general ad hoc networks. Also, in VANET, vehicles shoul d be able to authenticate each other to securely communicate with network-based infrastructure, and their locations and identifiers should not be exposed from the communication messages. This paper proposes V2I(Vehicular to Infra structure) authentication protocol that anonymity and untraceability of vehicular using Error Correcting Code that ge nerate encoding certification using generation matrix. The proposed scheme based on ECC resolves overhead problems of vehicular secure key management of KDC.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.12
• /
• pp.20-26
• /
• 2012

The newly introduced model of a STTC-based Distributed Wireless Communication System (DWCS) can provide the capability of joint control of the signals at multiple cells. This paper has considered the virtual cell systems: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. The considered system constructs DVC by using antenna selection method. Also, for multi-user high-rate data transmission, the proposed system introduces multiple antenna technology to get a spatial and temporal diversity gain and exploits space-time trellis codes known as STTC to increase a spectral efficiency.

• ETRI Journal
• /
• v.38 no.3
• /
• pp.444-454
• /
• 2016

Voice service is very demanding in cognitive radio networks (CRNs). The available spectrum in a CRN for CR users varies owing to the presence of licensed users. On the other hand, voice packets are delay sensitive and can tolerate a limited amount of delay. This makes the support of voice traffic in a CRN a complicated task that can be achieved by devising necessary considerations regarding the various network functionalities. In this paper, the support of secondary voice users in a CRN is investigated. First, a novel packet scheduling scheme that can provide the required quality of service (QoS) to voice users is proposed. The proposed scheme utilizes the maximum packet transmission rate for secondary voice users by assigning each secondary user the channel with the best level of quality. Furthermore, an analytical framework developed for a performance analysis of the system, is described in which the effect of erroneous spectrum sensing on the performance of secondary voice users is also taken into account. The QoS parameters of secondary voice users, which were obtained analytically, are also detailed. The analytical results were verified through the simulation, and will provide helpful insight in supporting voice services in a CRN.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.32B no.5
• /
• pp.720-729
• /
• 1995

We proposed a XMESH(crossed-mesh) topology as a suitable interconnection for the massively parallel computer architectures, and presented performance analysis of the proposed interconnection topology. Horizontally, the XMESH has the same links as those of the toroidal mesh(TMESH) or toroid, but vertically, it has diagonal cross links instead of the vertical links. It reveals desirable interconnection characteristics for the massively parallel computers as the number of nodes increases, while retaining the same structural advantages of the TMESH such as the symmetric structure, periodic placement of subsystems, and constant degree, which are highly recommended features for VLSI/WSI implementations. Furthermore, n*k XMESH can be easily expanded without increasing the diameter as long as n.leq.k.leq.n+4. Analytical performance evaluations show that the XMESH has a shorter diameter, a shorter mean internode distance, and a higher message completion rate than the TMESH or the diagonal mesh(DMESH). To confirm these results, an optimal self-routing algorithm for the proposed topology is developed and is used to simulate the average delay, the maximum delay, and the throughput in the presence of contention. In all cases, the XMESH is shown to outperform the TMESH and the DMESH regardless of the communication load conditions or the number of nodes of the networks, and can provide an attractive alternative to those networks in implementing massively parallel computers.

• Journal of Digital Contents Society
• /
• v.13 no.3
• /
• pp.353-358
• /
• 2012

Wireless sensor networks consist of resource constraint devices which typically send data measured by sensors attached to the end devices towards a coordinator. The most often used medium access control protocol used in wireless sensor networks is the standard IEEE 802.15.4, where it is wireless standard introduced for low power, low cost wireless communication with moderate data rates. In this paper, we present implementation of both the IEEE 802.15.4 protocol stack and UART interface on the TI CC2530. We show that data via UART of our implemented IEEE 802.15.4 board are transmitted correctly in terms of captured frames.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.12 no.2
• /
• pp.38-44
• /
• 2013

In this paper, we designed and implemented a mobile video transmission device with 1080i resolution and 30fps frame rate using wireless multi-access technologies. The video acquisition delay time of 16us and jitter of 21ms for this equipment were obtained, respectively. The device is designed to access various communication networks. In order to evaluate the performance of its video transmission capability, a server and monitoring viewer are implemented. In the performance test using LTE network, 211ms delay time was obtained at 3Mbps transmission. Rendering of 1fps frame rate at the 265kbps transmission was confirmed for the transmission test using Inmarsat network.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.8
• /
• pp.1024-1033
• /
• 1997

The past several years have witnessed an ever-increasing acceptance and adoption of parallel processing, both for high performance scientific computing as well as for more general purpose applications. Furthermore with increasing needs to perform the complex flow calculations in an efficient manner, the use of the message passing model on distributed networks has emerged as an important alternative to the expensive supercomputers. This work attempts to provide a generic framework to enable the parallelization of all CFD-related works using the master-slave model. This framework consists of (1) input geometry, (2) domain decomposition, (3) grid generation, (4) flow computations, (5) flow visualization, and (6) output display as the sequential components, but performs computations for (2) to (5) in parallel on the workstation clustering. The flow computations are parallized by having multiple copies of the flow-code to solve a PDE on different spatial regions on different processors, while their flow data are exchanged across the region boundaries, and the solution is time-stepped. The Parallel Virtual Machine (PVM) is used for distributed communication in this work.