• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.847-853
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• 2014

When a disaster occurs, effective alerts will reduce human life and property loss. The Integrated Emergency Alert System is a national disaster management system which integrates existing alert systems to deliver effective disaster alerts. Alert message exchange protocol is the essential technology for the System. In Korea, the first specification for "Common Alerting Protocol Profile for Integrated Emergency Alert System" was established in 2014. In this paper, we derive two additional requirements for more enhanced alert service and propose revision of the specification: multilingual alert service for foreigners and more flexible representation of target area. We review the associated foreign profile specifications as well as the domestic specifications to analyze these requirements. Finally, we propose the most efficient way to deliver multilingual alert message and to represent target area.

• Journal of Advanced Navigation Technology
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• v.12 no.3
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• pp.245-254
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• 2008

If the broadcast message is sent, first of all, the privileged users will decode the session key by using his or her personal key, which the user got previously. The user willget the digital information through this session key. As shown above, the user will obtain messages or session keys using the keys transmitted from a broadcaster, which process requires effective ways for the broadcaster to generate and distribute keys. In addition, when a user wants to withdraw or sign up, an effective process to renew a key is required. It is also necessary to chase and check users' malicious activities or attacking others. This paper presents a method called Traitor Tracing to solve all these problems. Traitor tracing can check attackers and trace them. It also utilizes a proactive way for each user to have effective renewal cycle to generate keys.

• Journal of Advanced Navigation Technology
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• v.19 no.4
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• pp.265-277
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• 2015

Automatic dependent surveillance-broadcast (ADS-B) is the core technology of communication, navigation and surveillance/air traffic management (CNS/ATM), automatically broadcasts its own position information using GNSS and has an advantage of lower geological constraints and faster update speed compared with legacy radar systems. EUROCONTROL defined all purpose structured eurocontrol surveillance information exchange (ASTERIX) CAT.021. ASTERIX CAT.021 is modified several times, but it has compatibility issues with previous version of it. In this paper, we have designed an efficient message processing module regardless of the version of ASTERIX CAT.021. This implemented module generates patterns to collect messages received from the network, after that, received messages are processed in the routine that is defined in accordance with the patterns.

• Journal of Broadcast Engineering
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• v.25 no.1
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• pp.36-47
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• 2020

The improved belief-propagation-based algorithms, such as normalized min-sum algorithm (NMSA) or offset min-sum algorithm (OMSA), are widely used to decode LDPC(Low-Density Parity-Check) codes because they are less computationally complex and work well even at low SNR(Signal-to-Noise Ratio). However, these algorithms work well only when an appropriate normalization factor or offset value is used. A new method that uses a CMD(Check Node Message Distribution) chart and least-square method, which has been recently proposed, has advantages on computational complexity over other approaches to get optimal coefficients. Furthermore, this method can be used to derive coefficients for each iteration. In this paper, we apply this method and propose an algorithm to derive a combination of normalization factor and offset value for a combined normalized and offset min-sum algorithm to further improve the decoding of LDPC codes. Simulations on the next-generation broadcasting standards, ATSC 3.0 LDPC codes, prove that a combined normalized and offset min-sum algorithm which takes the proposed coefficients as correction coefficients shows the best BER performance among other decoding algorithms.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.598-605
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• 2015

Effective alerts will drastically mitigate the disaster impacts. One way to enhance the effectiveness is to prepare multiple alert distribution channels. In this paper, we propose a new emergency alert distribution system that will solve the weaknesses of the current distribution systems, such as Cell Broadcasting System and T-DMB Automatic Emergency Alert Service. The weaknesses are: the limitation of message length, small portions of terminals that can receive and display the alert signal, and one-way communication service. To solve these problems, we propose an emergency alert distribution system over the Internet with RSS (Rich Site Summary) format. The system also has the capability of adaptive alert filtering according to the receiver characteristics. We analyzed the characteristics of RSS as an alerting format, and draw functional requirements satisfying use case scenarios. We designed the system only with major requirements and verified it on our test bed. Sending richer message contents through various receiving terminals, the system will achieve more effective emergency alert service.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.794-797
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• 2015

As the interest in VANET is increased, a study on the beacon message transmission between vehicles is actively being made. IEEE 802.11p/1609.4 standard is based on a multichannel system consisting of multiple service channels (SCH) and a control channel (CCH). Multiple SCHs are defined for nonsafety data transfer, while the CCH is used to broadcast safety messages called beacons and control messages (i.e., service advertisement messages). However, most messages broadcast in the only one CCH belong to safety application that must be contested in dense vehicular network. This paper suggests safety message transfer algorithm in dense vehicular congestion. The proposed algorithm is that the priority of safety messages is decided by decision tree and messages are stored in proper queues according to their priorities. Then, safety messages with higher priorities are sent in turn by CCH in the assigned time. The proposed algorithm decreases the beacon transmission delay and increase on the probability of a successful beacon reception in an IEEE 802.11p/1609.4-based network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.223-233
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• 2014

As a broadcast message authentication method in wireless sensor networks, ${\mu}$TESLA enables sensor nodes efficiently authenticate message from base station (BS). However, if we use ${\mu}$TESLA that has very short length of key slot in unattended wireless sensor network (UWSN), sensors may calculate a huge amount of hashs at once in order to verify the revealed secret key. In contrast, if we set the length of ${\mu}$TESLA's key slot too long in order to reduce the amount of hashs to calculate, BS should wait out the long slot time to release key. In this paper, we suggest variable key slot ${\mu}$TESLA in order to mitigate the problem. As showing experiment results, we prove that our suggestion improve sensor node's response time and decrease of number of hash function calculation.

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.399-409
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• 2003

In this paper, we present an Event Reporting which is one of the major items of MPEG-21 and exemplify two digital data broadcasting use case scenarios, and according1y we propose the Event Reporting message structure for MPEG-21 broadcasting contents that is based on these use case scenarios. Every interaction with a Digital Item in the multimedia framework can be called an Event. The need to standardize Event Reporting within the Multimedia Framework arise from the need to monitor and communicate amongst Peers and Users the Events relating to Digital Items and/or the programs and devices that operate on them at any given time. However, there are a number of difficulties in providing an accurate report about an Event. Different observers of the Event may have vastly different perspectives. In this paper, we describe a structure and vision of the Event Reporting. Besides we show the activities on MPEG-21 Event Reporting standardization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2131-2136
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• 2016

Before Industry 4.0, a purpose of manufacturing processes is simply overcoming the weakness of product line. However, Industry 4.0 should determine its method of work of facilities' own accord. Manufacturing processes such as FMS, AMS, MAS have been developed in these procedures, but there are possibilities of deadlock that can be happened for the reason of machine, agent or resource sharing. There were many studies to solve this problem. However, studies about prevention of deadlock happened in the situation that manufacturing processes are reconfigured dinamically because of human's intervention are incomplete. This paper proposes the model of the situation reconfigured dinamically and the method to prevent the deadlock in this situation. The proposed method adjusts production and manufacturing time by broadcasting time error messages to machines around when the manufacturing time of machine intervened by human is changed. Through this, it is anticipated to prevent the deadlock if conditions of the product line are changed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2413-2418
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• 2007

IN wireless sensor networks (WSNs), one challenging issue is to In wireless sensor networks (WSNs), one challenging issue is to construct a virtual backbone in a distributed and localized way while considering energy limitation. Dominating set has been used extensively as core or virtual backbone in WSNs for the purposes like routing and message broadcast. To ensure network performance, a good dominating set construction protocols should be simple and avoid introducing extra message. In addition, the resulting dominating set should be small, connected, and take into account the energy level at each node. This paper studies efficient and simple virtual backbone construction protocol using defer time in IEEE 802.15.4- based WSNs (e.g. Zigbee). The efficiency of our proposed protocol is confirmed through simulation results.