• Journal of Information Processing Systems
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• 제13권5호
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• pp.1158-1167
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• 2017

Many real-world applications information are organized and represented with graph structure which is often used for representing various ubiquitous networks, such as World Wide Web, social networks, and protein-protein interactive networks. In particular, similarity evaluation between graphs is a challenging issue in many fields such as graph searching, pattern discovery, neuroscience, chemical compounds exploration and so forth. There exist some algorithms which are based on vertices or edges properties, are proposed for addressing this issue. However, these algorithms do not take both vertices and edges similarities into account. Towards this end, this paper pioneers a novel approach for similarity evaluation between graphs based on formal concept analysis. The feature of this approach is able to characterize the relationships between nodes and further reveal the similarity between graphs. Therefore, the highlight of our approach is to take vertices and edges into account simultaneously. The proposed algorithm is evaluated using a case study for validating the effectiveness of the proposed approach on detecting and measuring the similarity between graphs.

• Journal of Communications and Networks
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• 제16권4호
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• pp.385-396
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• 2014

In this paper, we present a formal method for modeling and checking an enhanced version of the carrier sense multiple access with collision avoidance protocol related to the IEEE 802.11 MAC layer, which has been proposed as the standard protocol for wireless local area networks. We deal mainly with the distributed coordination function (DCF) procedure of this protocol throughout a sequence of transformation steps. First, we use the unified modeling language state machines to thoroughly capture the behavior of wireless stations implementing a DCF, and then translate them into the input language of the UPPAAL model checking tool, which is a network of communicating timed automata. Finally, we proceed by checking of some of the safety and liveness properties, such as deadlock-freedom, using this tool.

• 한국경제지리학회지
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• 제12권4호
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• pp.421-437
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• 2009

1978년 개혁 개방 이후, 중국은 해외 자본에 대한 의존도가 높은 '외생적 발전 전략'을 추진하였으나, 2000년 이후부터는 과학 기술 및 혁신 역량 강화에 초점을 둔 '내생적 발전 전략'을 추진하였다. 이제 중국에서의 기업 경영 활동은 선진 기술 및 경영 기법 이전을 촉진하는 새로운 제도와 조응하면서 차별적인 기업 혁신 네트워크를 형성하고 있다. 그 결과, 공간 경제의 성격은 초기 '수출 지향적 발전 공간'에서 '기술 지향적 발전 공간'으로 변화되었다. 이러한 맥락에서 본 논문은 중국 후기 사회주의 체제전환의 대표적 사례 공간인 상하이에 입지한 한국 투자 기업의 혁신 네트워크 특성을 기업내, 기업 간, 기업 외 관계 측면에서 분석함으로써, '기술 지향적 발전 공간'의 성격을 규명하고자 한다. 한국 투자 기업의 기업 내 관계에서는 사적 네트워크를 공적 네트워크로 전환함으로써 혁신 창출의 가능성과 경영 효율성을 극대화하려는 기업의 전략을 확인할 수 있었다. 기업 간 관계에서는 기업 규모, 산업 부문, 투자 유형 등에 따라서 차별적인 네트워크 특성을 보여주었다. 기업 외 관계는 외형적으로 제도적 개입 수준이 높은 공적 네트워크가 나타나고 있지만, 내면적으로는 ��시 관계(關係)에 기반을 둔 사적 네트워크가 나타났다. 결론적으로 중국 상하이의 공간적 특성은 외형적으로 '신 구제도 간의 상호작용과 구사회주의 체제 네트워크의 재구조화' 형태를 띠는 한편, 내면적으로 '신제도의 차단에 따른 구사회주의 체제 네트워크의 지속' 형태를 띠고 있어 '착근적' 성격과 '과잉 착근적' 성격이 함께 나타나고 있다.

• 노동경제논집
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• 제26권3호
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• pp.209-230
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• 2003

이 연구는 1996년 "아시아 사람들의 직장 생활에 관한 조사" 자료를 이용하여 한국의 취업시장에서 사회 연결망 활용에 영향을 미치는 요인을 분석하였다. 취업자를 하위 범주로 나누지 않고 보았을 때는, 사회 연결망이 공식 경로와 직접 접촉보다 더 중요한 취업방법임을 알 수 있다. 다항 로짓 분석 결과는 대체로 취업시장에서 유리한 위치에 있는 취업자 범주가 사회 연결망을 덜 활용한다는 점을 보여준다. 이것은 한국의 취업시장이 여러 가지 기준에 따라 뚜렷하게 나뉘어 있으며, 더 나은 사회 경제적 보상을 가져다 주는 취업시장에서는 공식 경로를 통한 경쟁이 주된 취업방법이라는 한국의 취업시장의 특징을 보여준다.

• International Journal of Railway
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• 제5권2호
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• pp.65-70
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• 2012

This paper introduced a novel railway system, Automatic Train Protection and Block (ATPB) briefly, which is proposed to improve the efficiency of existing regional train lines with low cost in Japan. The biggest superiority of ATPB system is a great use of universal and mature technologies, such as GPS and regular mobile telephone networks, so that there is nearly no increment of trackside equipments in the reconstruction. Then in order to guarantee the system safety, a formal model of ATPB is established and analyzed by formal method VDM++. Firstly, the specification is specified by VDM++ formally without ambiguity. Secondly, its internal consistency is proved by discharging the proof obligations. And finally, its satisfiability is checked by systematic testing, which executes specification and checks the outputs against corresponding inputs.

• 융합보안논문지
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• 제12권1호
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• pp.27-33
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• 2012

VANET(Vehicular Ad-hoc Network)은 지능형 차량들로 이루어진 애드혹 네트워크 환경으로서 최근 들어 그 연구가 활발하게 진행되고 있는 분야이다. VANET은 원활한 교통 소통, 사고 방지 등 여러 가지 편리한 기능들을 제공하지만 그 기반을 애드혹 네트워크에 두고 있기 때문에 애드혹 망에서 발생하는 보안 문제를 가지고 있고 또한 그 환경적 특성에 따라 추가적인 보안 요구 사항이 존재한다. 본 논문에서는 해쉬함수를 이용한 기존의 V2I 인증프로토콜에 대하여 검토하고, 이를 정형적 검증 방법인 Casper를 이용하여 인증 프로토콜의 안정성을 분석하였고 그 결과 안전함을 증명하였다.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.191-196
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• 1997

Fuzzy clustering has been playing an important role in solving many problems. Fuzzy c-Means(FCM) algorithm is most frequently used for fuzzy clustering. But some fixed point of FCM algorithm, know as Tucker's counter example, is not a reasonable solution. Moreover, FCM algorithm is impossible to perform the on-line learning since it is basically a batch learning scheme. This paper presents unsupervised learning networks as an attempt to improve shortcomings of the conventional clustering algorithm. This model integrates optimization function of FCM algorithm into unsupervised learning networks. The learning rule of the proposed scheme is a result of formal derivation based on the gradient descent procedure of a fuzzy objective function. Using the result of formal derivation, two algorithms of fuzzy cluster analysis, the batch learning version and on-line learning version, are devised. They are tested on several data sets and compared with FCM. The experimental results show that the proposed algorithms find out the reasonable solution on Tucker's counter example.

• Journal of Information Processing Systems
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• 제19권2호
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• pp.189-202
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• 2023

In the era marked by information inundation, social network analysis is the most important part of big data analysis, with clique detection being a key technology in social network mining. Also, detecting maximal balance clique in signed networks with positive and negative relationships is essential. In this paper, we present two algorithms. The first one is an algorithm, MCDA1, that detects the maximal balance clique using the improved three-way concept lattice algorithm and object-induced three-way concept lattice (OE-concept). The second one is an improved formal concept analysis algorithm, MCDA2, that improves the efficiency of memory. Additionally, we tested the execution time of our proposed method with four real-world datasets.

• Asian Journal of Innovation and Policy
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• 제4권2호
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• pp.242-262
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• 2015

The relationship between geographical proximity and academics' formal and informal knowledge-transfer activities in the network is analyzed with a mixed research method. With social network analysis as a basis, we have explored the networks between academics and firms in the 16 regions of South Korea. The result shows Seoul and Gyunggi are identified as central nodes, meaning that the academics in other regions tend to collaborate with firms in these regions. An econometric analysis is performed to confirm the localization of knowledge-transfer activities. The intensity of formal channels measured by the number of academic papers is negatively, but significantly associated with the geographical proximity. However, we have not found any significant relationship between the formality of the channels and geographical proximity. Possibly, the regional innovation systems in South Korea are neither big enough nor strong enough to show a localization effect.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(3)
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• pp.25-28
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• 2002

This paper introduce a personalized facial expression recognition system. Many previous works on facial expression recognition system focus on the formal six universal facial expressions. However, it is very difficult to make such expressions for normal person without much effort and training. And in these days, the personalized service is also mainly focused by many researchers in various fields. Thus, we Propose a novel facial expression recognition system with fuzzy neural networks and robust image processing.