• 한국정보과학회논문지:정보통신
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• 제33권2호
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• pp.175-182
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• 2006

IPv6 워킹 그룹에서 표준화된 CGA(Cryptographically Generated Addresses)는 링크상에서의 주소 변조 및 주소 도난 문제를 해결하고 전자서명을 제공하기 위해 제안되었으나 키 충돌이라는 문제가 발생할 수 있어서 이를 해결하기 위해 SEC(SECurity parameter) 필드를 도입하여 높은 보안이 필요한 경우에는 높은 SEC 값을 적용함으로써 키 충돌 확률을 감소시킨다. 하지만 SEC 값이 증가함에 따라 CGA 생성 시간이 무제한으로 증가하기 때문에 무선 환경에서 SEC 값이 높은 CGA를 적용하는 것은 불가능하다. 또, 낮은 SEC 값을 적용하는 경우 키 충돌은 높은 확률로 발생한다. 따라서, 본 논문에서는 계층적 애드 혹 환경에 적합한 개선된 CGA(MCGA: Modified CGA)를 제안한다. 제안되는 MCGA는 CGA에 비해 생성 시간이 매우 짧고 CGA와 마찬가지로 매우 작은 오버헤드로 전자 서명을 제공하며 계층적 네트워크 환경에서 사용함으로써 키 충돌 문제를 해결한다. MCGA는 계층적 애드 혹 환경뿐만 아니라 일반 IPv6 네트워크에서도 적용이 가능하다. 본 논문에서는 먼저 수학적 모델을 통해 MCGA와 CGA의 생성 시간을 분석하고 시뮬레이션을 통해 CGA와 MCGA의 생성시간을 측정하여 MCGA가 SEC 값이 0인 경우의 CGA에 비해 생성 시간이 평균 3.3배, 그리고 SEC 값이 1인 경우에는 평균 68,000배 짧다는 것을 보인다. 특히 SEC 값이 3 이상인 경우 애드 혹 환경뿐만 아니라 일반 네트워크에서도 부적절하다는 것을 증명한다.

• 한국군사과학기술학회지
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• 제21권5호
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• pp.658-664
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• 2018

In this paper, we propose a group key management scheme for very high confidential information in tactical wireless networks. For the proposed scheme, we consider the tactical networks that has a hierarchical topology and the nature of high confidential information. The leader node, which may have higher probability of good channel state than others, provides some data to all the network member in order to generate a geographical group key and it transmits the encrypted information with minimum transmission power level to others. By this scheme, the security and reliability for sharing confidential information is ensured. The performance of the proposed scheme is validated by mathematical analysis. It shows that the proposed scheme makes nodes to share a high confidential information securely if the proper parameters for network design are selected.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.69-77
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• 2015

MANET is composed of only the mobile nodes have a limited transmission range. The dynamic topology by the frequent movement of nodes makes routing difficult and is also cause exposed to security vulnerabilities. In this paper, we propose the security routing technique consisted of mechanism of two steps in order to respond effectively to attack by the modification of the routing information and transmit secure data. The hierarchical structure is used and the authentication node that issues the key of the nodes within each cluster is elected in this proposed method. The authentication node manages key issues and issued information for encrypting the routing information from the source node. The reliability value for each node is managed to routing trust table in order to secure data transmission. In the first step, the route discovery is performed using this after the routing information is encrypted using the key issued by the authentication node. In the second step, the average reliability value of the node in the found path is calculated. And the safety of the data transmission is improved after the average reliability value selects the highest path. The improved performance of the proposed method in this paper was confirmed through comparative experiments with CBSR and SEER. It was confirmed a better performance in the transmission delay, the amount of the control packet, and the packet transmission success ratio.

• 디지털산업정보학회논문지
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• 제13권2호
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• pp.43-51
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• 2017

Recently, MANET has been used in many fields as the range of applications increases. However, the dynamic topology that MANET has makes it difficult to route and provides the cause of exposure to security vulnerabilities. Therefore, the security features that can be robust to many attacks must have been applied in the routing technique provided in the MANET. In this paper, we propose a secure routing method that secure route is established by reliability evaluation of nodes and secure data communication has applied through key exchange mechanism. The proposed technique used hierarchical structure for efficiency of reliability evaluation of nodes. The reliability of nodes is performed by trust management node and reliability of nodes managed periodically is broadcasted. And the key exchange for secure data transmission is dene without CA as the certificate issuing organization. This allows fast key exchange and the integrity of data transmission improved. The proposed technique improves the security of the data transmission because a secure route to the destination node is established by the reliability evaluation and the data transmission is performed after the key between the source node and the destination node is exchanged through the established route.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권1호
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• pp.145-164
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• 2014

Network virtualization provides a promising tool to allow multiple heterogeneous virtual networks to run on a shared substrate network simultaneously. A long-standing challenge in network virtualization is the Virtual Network Embedding (VNE) problem: how to embed virtual networks onto specific physical nodes and links in the substrate network effectively. Recent research presents several heuristic algorithms that only consider single topological attribute of networks, which may lead to decreased utilization of resources. In this paper, we introduce six complementary characteristics that reflect different topological attributes, and propose three topology-aware VNE algorithms by leveraging the respective advantages of different characteristics. In addition, a new KS-core decomposition algorithm based on two characteristics is devised to better disentangle the hierarchical topological structure of virtual networks. Due to the overall consideration of topological attributes of substrate and virtual networks by using multiple characteristics, our study better coordinates node and link embedding. Extensive simulations demonstrate that our proposed algorithms improve the long-term average revenue, acceptance ratio, and revenue/cost ratio compared to previous algorithms.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1645-1649
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• 2012

Purpose: This study aimed to assess possible interactive effects of coping styles and psychological stress on depression and anxiety symptoms in Chinese women shortly after diagnosis of breast cancer. Methods: Four hundred and one patients with breast cancer were face-to-face interviewed by trained research staff according to a standardized questionnaire including information on socio-demographic characteristics, psychological stress, coping styles, and anxiety and depressive symptoms. Interactive effects were assessed by hierarchical multiple regression analyses. Results: There were significant associations of the four domains of psychological stress with anxiety and depressive symptoms except for the relationship between "worrying about health being harmed" and depressive symptoms. "Abreaction coping behavior" and "escaping coping behavior" significantly increased the level of both anxiety and depressive symptoms; whereas an "active coping style" reswulted in significant decrease. The interaction of "active coping behavior" with "worrying about health being harmed" significantly increased the risk of the anxiety symptoms, while adopting "self-relaxing coping behavior" was associated with significant decrease. The interaction of "worry about daily life and social relationship being restricted" with "escaping coping behavior" significantly increased the risk of the depressive symptoms. Conclusions: The results of this study suggest that certain coping styles might moderate the association of psychological stress with anxiety and depressive symptoms in Chinese women with breast cancer.

• 정보보호학회논문지
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• 제13권5호
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• pp.3-15
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• 2003

안전한 그룹 통신은 그룹에 속한 멤버들만이 안전하면서도 비밀스럽게 서비스를 받을 수 있도록 보장하는 것이며, 안전한 그룹 통신을 하기 위해서는 안전하게 그룹키를 분배하고, 그룹 멤버들에 대한 효율적인 관리가 중요하다. 또한, 그룹키를 생성, 분배 그리고 갱신하는데 있어 적은 통신량과 연산량이 필요하다. 본 논문에서는 그룹키를 생성하기 위해서, 잘 알려진 두 멤버간의 Diffie-Hellman 키 교환과 완전 이진 트리를 이용한 새로운 방법를 제안한다. 본 논문에서는 많은 양의 모듈러 멱승 연산의 일부를 곱셈 연산으로 대체하여 한 멤버에게 필요한 멱승 연산량을 최소화시킨다. 그리하여, 제안한 프로토콜은 그룹의 크기에 관계없이 프로토콜을 수행하기 위하여 각 그룹의 멤버는 항상 일정한 모듈러 멱승 연산과 곱셈 연산을 수행하며, 기존 프로토콜보다 전체 모듈러 멱승 연산량도 적다.

• 정보보호학회논문지
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• 제21권2호
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• pp.27-35
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• 2011

최근 IPTV 서비스 환경이 Mobile IPTV 서비스로 발전함에 따라 이동 단말에서 안전하게 IPTV 서비스를 제공받을 수 있도록 지원하는 보안 기술이 요구되고 있다. CAS는 IPTV 서비스 환경에서 콘텐츠 보호와 서비스 보호를 위해 사용되고 있다. 그러나 CAS의 경우 사용되는 보안키를 갱신하는 과정에서 사용하는 EMM으로 인한 채널 대역폭이 증가하고, 키 관리 서버에서 각 가입자들에게 서비스키를 갱신하기 위해 계산해야하는 연산량이 증가하는 문제점이 있다. 본 논문에서는 이러한 문제점을 해결하기 위해 서비스에 가입할 때 스마트카드 또는 USIM에 초기 마스터키를 보관하여 분배하고, 마스터키로부터 계층적 키를 유도함으로써 EMM을 사용하지 않고도 서비스키를 갱신 할 수 있도록 제안하였다.

• Agricultural and Biosystems Engineering
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• 제5권1호
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• pp.1-4
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• 2004

Community-based precision farming is a new concept of agricultural systems, which leads to organize groups of wise farmers and technology platforms in Japan. The wisdom farmers create a rational farming system to manage hierarchical variability: variability in farmers' community as well as variability of within-field and between-field. The technology platform develops and provides three key-technologies: mapping technology, variable-rate technology, and decision support systems available for rural constraints. Advancement of bio-production robots leads precision farming to the next level, where two technological innovations: how to produce and manage information-oriented fields and information-added products, can be attained.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 1998년도 춘계학술발표논문집
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• pp.28-33
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• 1998

대량의 영상데이터베이스에서 질의영상에 대한 유사영상을 검색할 때의 유사도 계산을 위한 시간소모는 영상의 실시간 검색효율을 저하시키는 요인이 된다. 본 논문에서는 키영상(key image)을 이용하여 영상데이터베이스의 각 영상과 키영상의 유사도를 미리 계산해 둠으로써 질의영상과 데이터베이스 영상간의 유사도 계산시간을 단축시킨다. 그리고 검색효율을 높이기 위해 1차적으로 칼라특징으로 유사영상들을 분류한 후, 1차 분류된 영상들만을 대상으로 계층적으로 질감특징값으로 영상을 비교함으로써 검색효율을 상승시킨다. Oracle 데이터베이스 상에서 본 계층적 내용기반 영상검색시스템을 구현하였다.