• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.566-568
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• 2000

급격한 통신의 발달은 분산시스템의 메시지 전달 환경을 FIFO 뿐만 아니라, 인과적 순서로도 가능케 한다. 낙관적 메시지 로깅 기법은 프로세스의 결함을 저비용으로 회복할 수 있다. 기존의 낙관적 메시지 로깅기법은 인과적 메시기 전달 순서를 보장해주는 환경에 적용되었을 때, 회복과정시 각 프로세스가 전체 프로세스에게 회복메시지를 브로드캐스팅함으로써 불필요한 오버헤드를 가진다. 그러나 제안하는 알고리즘은 회복과정을 시작하고 종료하는 시점에서 조정자 프로세스만 전체 프로세스에게 회복메시지를 브로드캐스팅함으로써 이러한 오버헤드를 줄일 수 있다. 즉, 조정자 프로세스가 아닌 프로세스는 정상수행시 유지하고 있는 상태정보에 기반하여 자신과 의존성이 존재하는 프로세스에게만 회복메시지를 선택적으로 멀티캐스팅함으로써 회복과정시 필요한 메시지의 수를 줄이고 전체적인 회복비용을 감소시킨다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.295-297
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• 2003

실시간 운영체제는 여러 개의 독립적인 태스크가 동시에 실행될 수 있는 멀티태스킹 환경을 제공한다. 이러한 독립적인 태스크들 사이에 정보를 주고받기 위해서는 태스크들 사이의 통신이 필요하며 이러한 ITC(Inter-Task Communication)를 지원하는 방법에는 Global Variable과 Message 전송 두 가지 방법이 있다. Global Variable 은 Data Corruption 의 위험이 있기 때문에 보통의 실시간 운영체제에서는 Message 전송 방식을 주로 사용하는데 이러한 방식에는 메시지 큐, 메시지 메일박스, 메시지 포트 등이 있다. 본 논문에서는 태스크들 간에 또는 태스크와 ISR(Interrupt Service Routine)이 여러 개의 메시지를 서로 전달할 수 있는 메시지 큐에 대해서 설명하고 있다. 또한 태스크 또는 ISR 이 메시지 큐로부터 메시지를 주고받을 때 메모리의 동적 할당을 보다 효과적으로 처리함으로써 효율적인 메시지 큐 제어기법에 대해서 제시하고 있다.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.441-443
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• 2011

OSEK COM은 OSEK/VDX에서 제안한 자동차 ECU의 태스크 간 통신 규약이다. 본 논문에서는 OSEK COM의 규약을 준수하는 내부 통신을 위한 메시지 송수신 메커니즘을 제시한다. 제시한 메커니즘의 타당성을 검토하기 위하여 ARM 프로세서가 탑재된 EZ-AT7에서 태스크 간의 정상적인 내부 통신 동작 상태를 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.203-212
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• 2007

An advanced vehicle safety system can be constructed by exchanging danger-related information ,such as urgency stop, traffic accident, obstacle, and car trouble, among the vehicles. However, because network topology changes rapidly and frequently due to the mobility of vehicles, it is impossible to configure the network for information forwarding in this environment. In the most of vehicle safety communication applications, an emergency message is propagated in a form of broadcasting. The simple broadcasting causes a lot of problems in terms of efficiency due to multi-hop area and radio collision problem. This paper proposes a method of selective message forwarding with stem and branch structure for propagating the emergency messages. However, the proposed method raise the efficiency of message transmission with the selective forwarding based on the priority assignment as its location. We analyze and evaluate the performance by comparing the proposed scheme with other schemes that are presented in the paper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.471-478
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• 2013

Powerful error control and increase in the number of bits per symbol should be provided for future high-quality communication systems. Each message bit may have different importance in multimedia data. Hence, UEP(unequal error protection) may be more efficient than EEP(equal error protection) in such cases. And the LDPC(low-density parity-check) code shows near Shannon limit error correcting performance. Therefore, the effect of UEP with LDPC codes is analyzed for high-quality message data in this paper. The relationship among MSE(mean square error), BER(bit error rate) and the number of bits per symbol is analyzed theoretically. Then, total message bits in a symbol are classified into two groups according to importance to prove the relationship by simulation. And the UEP performance is obtained by simulation according to the number of message bits in each group with the constraint of a fixed total code rate and codeword length. As results, the effect of UEP with the LDPC codes is analyzed by MSE according to the number of bits per symbol, the ratio of the message bits, and protection level of the classified groups.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.561-565
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• 2013

Due to the development of industrial networks, As an alternative to traditional fieldbus, fieldbus networks move to standard Ethernet that high data throughput and scalable technology. Hence we suggest transmission algorithm which satisfied requirements for hard-real time about periodic and aperiodic message based on general-purposed ethernet, and suggest scheduling algorithm for each message.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.319-324
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• 2012

Vehicle safety communications is one among the important technologies in order to protect a car accident. For this, many protocols forwarding a safe message have studied to protect a chain-reaction collision when a car accident occurs. most of these protocols assume that the time of generating a safe message is the same as an accident's. If a node predicts some traffic hazard and forwards a safe message, a driver can response some action quickly. So, In this paper, we proposes a traffic hazard prediction algorithm using the communication technique. As a result, we show that the frame reception success rate of using our algorithm to the previous protocol improved about 4~5%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1969-1975
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• 2015

The Internet of Things (IoT), in which resource constrained devices communicate with each other, requires a lightweight security protocol. In this paper, we propose a new message authentication scheme using a hash tree for lightweight message authentication in the Datagram Transport Layer Security (DTLS) protocol. The proposed scheme provides lightweight secure operations compared with those of the DTLS protocol. Besides, it provides more suitable performance than the DTLS protocol for an IoT environment, thanks to the reduced use of message authentication code.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.765-768
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• 2007

In this paper, the security evaluation method about mobile web services message is suggested in the method for improving the safety an reliability about the mobile web services message. In order that the goal of this paper is accomplished, the security threat and the security vulnerability which can be occurred in the mobile web services message are defined. The evaluation method for performing the security evaluation about the mobile web services message is defined. Also, the requirements for the mobile web services message security evaluation are defined. Finally, the evaluation framework for performing the mobile web services message security evaluation is constituted, and the evaluation scenario example is suggested. By using the mobile web services message security evaluation defined in the paper, before the mobile web services is deployed, the security threats and security vulnerability can be verified. Also, the countermeasure for the security threat and security vulnerability discovered in the verification result can be prepared. Therefore, the sorority and reliability about the mobile web services can be improved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.533-535
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• 2017

MQTT provides three QoS levels on top of the TCP/IP layer to ensure message delivery reliability. However, in an environment where messages are concurrently transmitted and received in a node, messages are lost due to the delivery method for QoS level. In this paper, it construct an experimental environment in which MQTT generates concurrently messages, and confirm the message reliability according to QoS level. Therefore, we analyze the message reception ratio on the subscriber side by changing number of publisher and transmission cycle of message. Experimental results show that the message reception ratio of 1 and 2 except QoS level 0 decreases as the number of publisher increases or the message transmission cycle increases.