• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.6
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• pp.1462-1477
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• 2024

With the evolving complexity of connected vehicle features, the volume and diversity of data generated during driving continue to escalate. Enabling data sharing among interconnected vehicles holds promise for improving users' driving experiences and alleviating traffic congestion. Yet, the unintentional disclosure of users' private information through data sharing poses a risk, potentially compromising the interests of vehicle users and, in certain cases, endangering driving safety. Federated learning (FL) is a newly emerged distributed machine learning paradigm, which is expected to play a prominent role for privacy-preserving learning in autonomous vehicles. While FL holds significant potential to enhance the architecture of the Internet of Vehicles (IoV), the dynamic mobility of vehicles poses a considerable challenge to integrating FL with vehicular networks. In this paper, a novel clustered FL framework is proposed which is efficient for reducing communication and protecting data privacy. By assessing the similarity among feature vectors, vehicles are categorized into distinct clusters. An optimal vehicle is elected as the cluster head, which enhances the efficiency of personalized data processing and model training while reducing communication overhead. Simultaneously, the Local Differential Privacy (LDP) mechanism is incorporated during local training to safeguard vehicle privacy. The simulation results obtained from the 20newsgroups dataset and the MNIST dataset validate the effectiveness of the proposed scheme, indicating that the proposed scheme can ensure data privacy effectively while reducing communication overhead.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.243-250
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• 2010

Vehicular communication networking is one of the most important building blocks of Intelligent Transportation System (ITS). The vehicular communication network is a wireless communication system enabling vehicles to communicate with each other as well as with roadside base stations. Mobility management of vehicles which move at high speeds and occasionally make a long journey is an interesting research area of vehicular communication networks. Recently, The Proxy Mobile IPv6 (PMIPv6) protocol is proposed for network-based mobility management to reduce the overhead of mobile nodes. PMIPv6 shifts the burden of the mobility management from mobile nodes to network agents to decrease the overhead and latency for the mobility management. In this paper, we derive the scenario of deploying PMIPv6 in vehicular communication networks and propose a new LMA handover mechanism for realizing the scenario. By carrying out the ns-2 based simulations, we verify the operability of the proposed mechanism.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.3
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• pp.67-72
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• 2018

Recently, noise reduction in an axial fan producing the small pressure rise and large flow rate, which is one type of turbomachine, is recognized as essential. This study describes the design and optimization techniques of MPI parallel program to simulate the flow-induced noise in the axial fan. In order to simulate the code using 100 million number of grids for flow and 70,000 points for noise sources, we parallelize it using the 2D domain decomposition. However, when it is involved many computing cores, it is getting slower because of MPI communication overhead among nodes, especially for the noise simulation. Thus, it is adopted the one-sided communication to reduce the overhead of MPI communication. Moreover, the allocated memory and communication between cores are optimized, thereby improving 2.97x compared to the original one. Finally, it is achieved 12x and 6x faster using 6,144 and 128 computing cores of KISTI Tachyon2 than using 256 and 16 computing cores for the flow and noise simulations, respectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.75-87
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• 2010

Secure communication has been one of the main challenges in vehicular ad hoc networks(VANET) since broadcast messages from nearby vehicles contain life-critical information for drivers and passengers. So far various secure communication schemes have been proposed to secure the communication in VANET, and they satisfy most security requirements. However most of them need to put trust on roadside units(RSUs), which are usually deployed in unattended area and vulnerable to compromise. In this paper, we propose a secure communication scheme, which does not need to put trust on RSUs. And we adopt a grouping technique to averagely divide the huge burden in the server without jeopardizing the anonymity of users. Moreover we design a complete set of protocols to satisfy common security requirements with a relatively lower hardware requirement. At last, we evaluate the scheme with respect to security requirements, communication overhead, storage overhead and network performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.2
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• pp.130-139
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• 2013

In recent, the communication networks of wind power farm are becoming crucial technologies for monitoring and controlling the large-scale offshore wind power farm. In this paper, EPON based communication network architectures are proposed in order to combat the problems of conventional Ethernet based communication network such as delay, data processing overhead and the fairness of data transmission among turbines in offshore wind power farm. The proposed architecture constructs the point to multi-point network by using OLT and ONUs installed in central control center and wind turbines respectively. The EPON based communication network architecture has low cost, high reliability, and fair transmission capability. To evaluate the performance of proposed architectures, the wind power farm based on IEC 61850 is modelled by using OPNET The simulation results are analyzed and compared with conventional Ethernet based communication network in terms of the overhead, delay and fairness of data transmission.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.559-565
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• 2009

Power dissipation during scan testing is becoming an important concern as design sizes and gate densities increase. The high switching activity of combinational circuits is an unnecessary operation in scan shift mode. In this paper, we present a novel architecture to reduce test power dissipation in combinational logic by blocking signal transitions at the logic inputs during scan shifting. We propose a unique architecture that uses dmuxed scan flip-flop (DSF) and transmission gate as an alternative to muxed scan flip-flop. The proposed method does not have problems with auto test pattern generation (ATPG) techniques such as test application time and computational complexity. Moreover, our elegant method improves performance degradation and large overhead in terms of area with blocking logic techniques. Experimental results on ITC99 benchmarks show that the proposed architecture can achieve an average improvement of 30.31% in switching activity compared to conventional scan methods. Additionally, the results of simulation with DSF indicate that the powerdelay product (PDP) and area overhead are improved by 28.9% and 15.6%, respectively, compared to existing blocking logic method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3366-3383
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• 2012

Reliance on the Internet has introduced Voice over Internet Protocol (VoIP) to various security threats. A reliable security protocol and an authentication scheme are thus required to prevent the aforementioned threats. However, an authentication scheme often demands additional cost and effort. Accordingly, a security framework for known participants in VoIP communication is proposed in this paper. The framework is known as Randomness-Optimized Self-Securing (ROSS), which performs authentication automatically throughout the session by optimizing the uniqueness and randomness of the communication itself. Elliptic Curve Diffie-Hellman (ECDH) key exchange and Salsa20 stream cipher are utilized in the framework correspondingly to secure the key agreement and the communication with low computational cost. Human intelligence supports ROSS authentication process to ensure participant authenticity and communication regularity. The results show that with marginal overhead, the proposed framework is able to secure VoIP communication by performing reliable authentication.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1224-1228
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• 2010

The existing cluster-based routing protocols have some problems. Firstly, because of selecting cluster head at random, they occur a node concentration problem. Secondly, they have a low reliability for data communication due to the less consideration of node communication range. Finally, data communication overhead is greatly increased because of sending all sensor node information to sink node for constructing clusters. To solve these problems, we in this paper, propose a cluster-based routing protocol using message reception success rate. Firstly, to solve the node concentration problem, we design a cluster head selection algorithm based on node connectivity and devise cluster spliting/merging algorithms. Secondly, to guarantee data communication reliability, we use message reception success rate. Finally, to reduce data communication overhead, we use only neighbor nodes information at both cluster construction and cluster head selection.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.1-8
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• 2021

In Mobile Ad-Hoc Network (MANET) Application, routing protocol is essential to ensure successful data transmission to all nodes. Ad-hoc On-demand Distance Vector (AODV) Protocol is a reactive routing protocol that is mostly used in MANET applications. However, the protocol causes Route Request (RREQ) message flooding issue due to the broadcasting method at the route request stage to find a path to a particular destination, where the RREQ will be rebroadcast if no Request Response (RREP) message is received. A scalable neighbor-based routing (SNBR) protocol was then proposed to overcome the issue. In the SNBR protocol, the RREQ message is only rebroadcast if the number of neighbor nodes less than a certain fix number, known as drop factor. However, since a network always have a dynamic characteristic with a dynamic number of neighbor nodes, the fix drop factor in SNBR protocol could not provide an optimal flooding problem solution in a low dense network environment, where the RREQ message is continuously rebroadcast RREQ message until reach the fix drop factor. To overcome this problem, a new broadcasting method as Dynamic SNBR (DSNBR) is proposed, where the drop factor is determined based on current number of neighbor nodes. This method rebroadcast the extra RREQ messages based on the determined dynamic drop factor. The performance of the proposed DSNBR is evaluated using NS2 and compared with the performance of the existing protocol; AODV and SNBR. Simulation results show that the new routing protocol reduces the routing request overhead, energy consumption, MAC Collision and enhances end-to-end delay, network coverage ratio as a result of reducing the extra route request messages.

• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.531-537
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• 2001

In order for all participants at video conference to communicate mutually, the conference key should be necessary. In this paper, we present the communication protocol that generates a conference key efficiently based on $(\upsilon,\kappa,\lambda)$-configuration, one class of block designs, which minimizes message transmission overhead needed for this key. Especially, in the case of ${\lambda}=1$, the protocol requires only $O(\sqrt[v]{v})$ messages, where v is the number of participants.