• International Journal of Computer Science & Network Security
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• v.24 no.9
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• pp.162-168
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• 2024

VANET (vehicular ad hoc network) refers to the case networks designed for vehicles. Such networks are established among the vehicles which are equipped with communication tools. Within these networks, vehicles are regarded as the network nodes. On time and on schedule transmission of data is of high significance for these networks. In order to accomplish the objective of on-time data transmission, specific electronic equipment is embedded in each vehicle which maintains ad hoc communications among the passengers. Information about traffic, road signs and on-line observation of traffic status can be transmitted via these networks; such data makes it possible for the driver to select the best route to reach his destination. If there are not any infrastructures, two broadcasting approaches can be considered: overflowing and rebroadcasting. The overflowing approach leads to heavy traffic. Hence, the challenge we face is to avoid the broadcasting flood. In this paper, an approach for the management of the broadcasting flood is proposed based on fuzzy theory. The proposed method is assumed to have better performance and efficiency than any other approaches in terms of crash rate, the rate of message success and delay

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3672-3679
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• 2012

Vehicle Ad hoc Network (VANET) is next-generation network technology to provide various services using V2V (Vehicle-to-Vehicle) and V2I (Vehicle-to-Infrastructure). In VANET, many researchers proposed various studies for the safety of drivers. In particular, using the emergency message to increase the efficiency of traffic safety have been actively studied. In order to efficiently transmit to moving vehicle, to send a quick message to as many nodes is very important via broadcasting belong to communication range of vehicle nodes. However, existing studies have suggested a message for transmission to the communication node through indiscriminate broadcasting and broadcast storm problems, thereby decreasing the overall performance has caused the problem. In addition, theses problems has decreasing performance of overall network in various form of road and high density of vehicle node as urban area. Therefore, this paper proposed Clustering based Routing Algorithm (CBRA) to efficiently transmit emergency message in high density of vehicle as urban area. The CBRA managed moving vehicle via clustering when vehicle transmit emergency messages. In addition, we resolve linkage problem between vehicles according to various form of road. The CBRA resolve link brokage problem according to various form of road as urban using clustering. In addition, we resolve broadcasting storm problem and improving efficacy using selection flooding method. simulation results using ns-2 revealed that the proposed CBRA performs much better than the existing routing protocols.

• Journal of Advanced Navigation Technology
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• v.18 no.5
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• pp.421-428
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• 2014

GPS satellite positions can be obtained from the navigation message transmitted from the GPS satellite. In this paper, the accuracy of broadcast orbit and clock are analyzed by comparing with the NGA precise ephemeris. For analyzing global and local orbit errors in 2004 to 2013, GPS satellite visibilities are calculated in Korea. Local RMS of 3D orbit error and SISRE are 4 cm and 3 cm less than global RMS of 3D orbit errors and SISRE. Orbit and clock errors are calculated for each GPS satellite Block for 10 years. SISRE of Block IIA satellites are 2.8 times greater than Block IIF satellites. The correlation between orbit errors and shadow condition is analyzed. The orbit errors in shadow is 2.1% higher than that in sunlight. Correlation analysis between the orbit errors and solar/geomagnetic index shows that orbit errors has a high correlation with from 2004 to 2008. However, the correlation became low since 2009.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.62-69
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• 2004

The cluster structure reduces the number of retransmission messages, when a broadcast to all hosts in ad hoc network is needed. A cluster maintenance scheme is employed to preserve this advantage from time to time. However, most of the cluster maintenance schemes require additional control messages for cluster reformation as well as control messages for acquiring neighbor information. This mitigates the advantages of employing cluster structure in ad hoc network. In this paper, a cluster maintenance scheme which forces only clusterheads to broadcast control messages during hello time is proposed. When the cluster reformation is needed, the proposed scheme employs a strategy to reduce the control messages to a minimum. In these processes, the proposed scheme doesn't violate the definition of 2-cluster and produces the clusters in fully distributed method. The simulation results prove that our scheme is better than LCC(1).

• Journal of Advanced Navigation Technology
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• v.12 no.1
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• pp.34-45
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• 2008

Broadcast encryption schemes are applied to transmit digital informations of multimedia, software, Pay-TV etc. in public network. User acquires message or session key to use key that broadcaster transmits, broadcaster need process that generation and distribution key in these process. Also, user secession new when join efficient key renewal need. In this paper, introduce about efficient key generation and distribution, key renewal method. The temporary conference environment base structure against an each mobile device wild gap. Without the transmission possible, it follows infrequent location change and with the quality where the key information change flow. Thus, in this paper, in order to apply to the embedded computing environment and the key generation and the efficient key renewal are done when the mobile device is used of the specify space it proposes.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.399-404
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• 2020

The Disaster text service is a text-based service for public alert. But, foreigners who are not familiar with korean can not understand exactly the disaster text messages provided. Using multimedia information such as images is expected to solve this problem. However, the current disaster message service method is not suitable for multimedia information delivery. This study proposes a firmware-based disaster character service method for displaying disaster image in a terminal. A device using this method should store images corresponding to the type of disaster and use special characters to inform the presentation of image in a terminal. This approach can be implemented in the new firmware installed device and it can be work with the existing device.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.11-16
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• 2004

Recently, collaborative works are increased more and more over the distributed heterogeneous computing environments. The availability of high-speed wide-area networks has also enabled collaborative multimedia applications such as video conferencing, distributed interactive simulation and collaborative visualization. Distributed high performance computing and collaborative multimedia applications, it is extremely important to efficiently perform group communication over a heterogeneous network. Typical group communication patterns are broadcast and Multicast. Heuristic algorithms such as FEF, ECEF, look-ahead make up the message transmission tree for the broadcast and multicast over the distributed heterogeneous systems. But, there are some shortcomings because these select the optimal solution at each step, it may not be reached to the global optimum In this paper, we propose a new heuristic algerian that constructs tree for efficiently collective communication over the previous heterogeneous communication model which has heterogenity in both node and network. The previous heuristic algorithms my result in a locally optimal solution, so we present more reasonable and available criterion for choosing edge. Through the performance evaluation over the various communication cost, improved heuristic algorithm we proposed have less completion time than previous algorithms have, especially less time complexity than look-ahead approach.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.113-116
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• 2001

In this paper, a new multicasting scheduling is proposed for WDM single-hop broadcast network. The main idea of traditional multicast scheduling algorithms is partitioning the multicast group into several subgroups to reduce the delay time after receiving previous message. Those partitioning algorithms are grouping method of receivers already tuned to transmitters wavelength. However, multicast scheduling shows better performance by considering the previous status of receivers. Thus, in this paper, a new subgrouping method is proposed to minimize delay through collecting the current status of receivers. This method is operated by using the tunable transceiver in WDM single hop broadcasting network and uses fixed control channel for collecting the status of receivers. In addition, we analyzed the performance of proposed method through the computer simulation and then compared with existing multicast scheduling algorithm.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.327-338
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• 2010

Complete Subtree scheme(CS) is a well known broadcast encryption scheme to perform group rekeying in a stateless manner. However, statelessness comes at a cost in terms of storage and message overhead in transmitting key material. We propose a Merged Complete Subtree scheme(MCS) to reduce the communication overhead. It is more practical to make broadcast encryption schemes in network environments with limited bandwidth resources. We define all possible subset unions for ever two subsets of CS as new subsets having own key. The modification causes more storage overhead. Nevertheless, it is possible to make the size of a header, including key materials, half using subset unions of MCS, because the size of a header depends on the number of used subsets. Our evaluation therefore shows that the proposed scheme significantly improves the communication overhead of CS, reducing by half the rekey communication cost. The proposed scheme has the advantage of rekey communication cost when the number of revoked users is significant percentage of the number of potential users. The proposed scheme is fully collusion resistant.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.53-61
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• 2008

Public Key Broadcast Encryption (PKBE) allows a sender to distribute a message to a changing set of users over an insecure channel. PKBE schemes should be able to dynamically exclude (i.e., revoke) a certain subset of users from decrypting a ciphertext, so that only remaining users can decrypt the ciphertext. Another important requirement is for the scheme to be forward-secrecy. A forward-secure PKBE (fs-PKBE) enables each user to update his private key periodically. This updated private key prevents an adversary from obtain the private key for certain past period, which property is particularly needed for pay-TV systems. In this paper, we present a fs-PKBE scheme where both ciphertexts and private keys are of $O(\sqrt{n})$ size. Our PKBE construction is based on Boneh-Boyen-Goh's hierarchical identity-based encryption scheme. To provide the forward-secrecy with our PKBE scheme, we again use the delegation mechanism for lower level identities, introduced in the BBG scheme. We prove chosen ciphertext security of the proposed scheme under the Bilinear Diffie-Hellman Exponent assumption without random oracles.