• Journal of KIISE:Computer Systems and Theory
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• v.26 no.2
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• pp.155-163
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• 1999

방송통신 프로토콜은 메시지들의 순서가 바뀌거나 메시지 손실이 발생하는 문제점을 갖는 비신뢰 통신 프로토콜이다. 아메바 시스템에서 사용하는 순차적 기반 방송통신 프로토콜은 신뢰성 있고 전송되는 모든 메시지들의 순서를 일정하게 유지할 수 있는 통신 방법중의 하나이다. 비록 아메바 시스템에서는 순차기의 고장이 발생하였을 경우 선출알고리즘을 사용하여 대처하지만, 대부분의 순차기기반 방송통신 프로토콜들은 단일 노드 고장이라는 한가지 단점을 가지고 있다. 이 단점은 순차기 고장으로 인해 전체 시스템에서의 방송통신을 사용할 수 없는 매우 치명적인 현상이 발생한다. 본 논문에서는 전송되는 모든 메시지들의 순서를 일정하게 유지하면서 순차기의 작업량을 줄이는 고장감내 방송통신 프로토콜 알고리즘을 제안한다. 제안된 알고리즘에서는 다수의 순차기를 사용하고 손실된 메시지를 재전송하기 위한 논리적 노드인 기록노드를 사용한다. 또한 순차기노드의 고장을 검출하기 위하여 순차기들간의 논리적 리스트를 구성한다. 제안된 알고리즘의 성능을 측정하기 위하여 시뮬레이션 하였고 실제 유닉스를 기반으로 하는 랜에서 실험했다. 시뮬레이션결과, 제안된 알고리즘은 기존의 순차기기반 알고리즘보다 빠르고, 고장감내 성격을 갖고 있음을 알 수있다.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.705-713
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• 2003

For group security to protect group data or to charge, group keys should be updated via key update messages when the membership of group changes. If we lose these messages, it is not possible to decrypt the group data and so this is why the recovery of lost keys is very significant. Any message lost during a certain member is logged off can not be recovered in real-time. Saving all messages and resending them by KDC (Key Distribution Center) not only requests large saving spaces, but also causes to transmit and decrypt unnecessary keys. This paper analyzes the problem of the loss of key update messages along with other problems that may arise during member login procedure, and also gives an efficient method for recovering group keys and auxiliary keys. This method provides that group keys and auxiliary keys can be recovered and sent effectively using information stored in key-tree. The group key generation method presented in this paper is simple and enable us to recover any group key without storing. It also eliminates the transmissions and decryptions of useless auxiliary keys.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.1-8
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• 2008

The belief propagation method that has been studied recently yields good performance in disparity extraction. The method in which a target function is modeled as an energy function based on Markov random field(MRF), solves the stereo matching problem by finding the disparity to minimize the energy function. MRF models provide robust and unified framework for vision problem such as stereo and image restoration. the belief propagation method produces quite correct results, but it has difficulty in real time implementation because of higher computational complexity than other stereo methods. To relieve this problem, in this paper, we propose a fast algorithm of the belief propagation method. Energy function consists of a data term and a smoothness tern. The data term usually corresponds to the difference in brightness between correspondences, and smoothness term indicates the continuity of adjacent pixels. Smoothness information is created from messages, which are assigned using four different message arrays for the pixel positions adjacent in four directions. The processing time for four message arrays dominates 80 percent of the whole program execution time. In the proposed method, we propose an algorithm that dramatically reduces the processing time require in message calculation, since the message.; are not produced in four arrays but in a single array. Tn the last step of disparity extraction process, the messages are called in the single integrated array and this algorithm requires 1/4 computational complexity of the conventional method. Our method is evaluated by comparing the disparity error rates of our method and the conventional method. Experimental results show that the proposed method remarkably reduces the execution time while it rarely increases disparity error.

• Convergence Security Journal
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• v.10 no.2
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• pp.51-57
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• 2010

This paper proposes extended trust evaluation mechanism which is able to become the standard of the node selection which provides a better service by using the basic transaction message which occurs from within the mobile Ad-hoc network and the additional transaction message and add confidence value. Furthermore, throughout the simulation shows the efficiency of the proposed trust evaluation mechanism.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.265-266
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• 2016

VANET은 짧은 거리 이동 통신을 이용한 MANET의 일종으로 노드들이 차량들로 이루어져 있다. 차량들은 차량들 사이에 메시지 교환과 도로 측면의 인프라와 메시지를 교환한다. VANET을 실세계에 적용 시에 가장 주요한 요소는 보안 문제이다. 다양한 보안 문제가 있지만 이상 행동을 하는 차량은 가장 위협적인 위험이 되고 있다. 비인증된 공격은 PKI 보안 메커니즘으로 탐지하고 제거될 수 있지만 인증된 노드의 이상 행동은 주요한 문제가 되고 있다. 본 논문에서는 이러한 이기적인 행동이나 감염되어 이상적인 행동을 하는 노드들을 탐지하는 기법을 제안한다. 이를 위해 TPM 기능을 활용하여 비콘 메시지 교환을 통해 차량들 간의 신뢰관계를 형성하며 알람 메시지를 신뢰관계가 형성된 차량들과 인프라를 이용하여 부정 행위를 하는 노드를 탐지한다.

• Journal of the HCI Society of Korea
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• v.6 no.2
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• pp.1-9
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• 2011

Increasing communication through social media forming impression becomes more important. In this research, how three stimulus can build the impression of Twitter Account Owner(TAO) such as the types of the profile pictures, the types of timeline messages and the number of followers. We analysed the feelings of respondents when they face TAO's formal picture and informal picture, informative message and normal message, the number of followers. We, in addition, measured the willingness of respondents whether they want to develop their relationship online and offline as well. As a result, informative message draws positive reliability and makes respondent want to build deeper relationship with TAO at online. Respondent answered TAO's informal picture was more likable than formal picture and more reliable when informative message and formal picture were provided together. Our study shows that there are actual differences at attitudes of respondents by the types of the profile pictures and the types of timeline messages. Thus, we can conclude that TAOs can modify their impressions at online as they hope to.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.137-144
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• 2005

Many reliable group communication algorithms were presented to satisfy predetermined message ordering properties in small or medium-scale distributed systems. However, the previous algorithms with their strong reliability properties may be unappropriate for large-scale systems. To address this issue, some epidemic-style group communication algorithms were proposed for considerably improving scalability while guaranteeing the reasonably weaker reliability property than the existing ones. The algorithms are all designed for ensuring the atomic order message delivery property. But, some distributed applications such as multimedia systems and collaborative work, may require only the weaker message ordering property, i.e., causal order delivery. This paper proposes an efficient epidemic-style group communication algorithm ensuring causal order delivery to provide the indigenous scalability of the epidemic-style approach.

• Archives of design research
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• v.18 no.3 s.61
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• pp.129-138
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• 2005

It has been assumed that the clarification of a message is a necessary element for successful communication. However, in the today's complicated and changing environment of business marketing media, it is shown that the clarification of the message of advertisement may inhibit the effectiveness of communication. This study was to examine what was effective communication in advertisement when the company, provoking the people's negative emotional response, needs to establish new identities such as the goals and the special fields of business. In particular, the study was to investigate what effect the advertising strategy of strategically emitting ambiguous messages makes on the consumer's recognition, emotional attitude, reliability, and attitude towards the company. It was hypothesized that an ambiguous message in an advertisement has an effect on the consumer's recognition, emotional attitude, reliability, and attitude towards the company. Three texts from the 'Imagination Praises' campaign of KT&G which has been in process since 2003 were systematically sampled and the survey was performed by the means of questionnaires made on the sample The results showed that the ambiguous message of advertising texts gained better responses on the consumer's attention, good impression, affirmation, memory, sympathy than the dear message and that the ambiguous message had an effect on the consumer's attitude towards the advertisement itself. Thus, it could be tentatively concluded that the ambiguous message could be more effective in recognition and recall to promote the changes of identities of the company having the people's unfavorable emotion. But there wasn't any evidence that an ambiguous message in an advertisement was more effective in terms of the consumer's emotional response, reliability, and attitude towards the company. From this, it could be inferred that the receiver had an uncomfortable, doubtful and negative attitude about the implicit expressive code contained in the message. In the future deeper qualitative studies can compensate for the limited explanation of this empirical study focused on statistical analyses.

• 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 KIEE Conference
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• 2001.11c
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• pp.127-129
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• 2001

CAN 통신은 네트워크 시스템 제어를 통한 각종 산업설비에서 제어 및 자동화 관련 장비들간에 데이터 교환을 위한 통신망으로 널리 사용되고 있다. 이러한 CAN통신을 응용하여 실시간 메시지 송수신이 가능한 시스템을 구성하려면 메시지의 특성분류 및 메시지의 증가에 따른 트레픽 발생을 고려해야 한다. CAN의 제한된 속도에 따른 실시간 메시지 전송의 여부는 데드라인을 통한 메시지 설계로 성능을 보장받고 있다. 하지만 이러한 메시지의 송수신에 있어 단순 CAN네트워크 망에 의존한 설계만으로 메시지의 신뢰성을 보장받을 수 없다. 네트워크 상황에 따른 버퍼를 통한 능동적인 메시지 스케줄링 방법을 통하여 성능효과를 보장받을 수 있는 방법을 제안한다.