• Journal of Information Processing Systems
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• v.13 no.5
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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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• v.16 no.4
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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.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.4
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• pp.421-437
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• 2009

China has transformed her strategies for economic development from exogenous development founded on foreign capitals to endogenous development based on enhancing technology innovation capabilities since 2000. More specifically, Chinese business activities have coupled with new institutional settings which enable them to facilitate advanced technology and management methods. As a result, the characteristics of the spatial economy in China are likely to transfer from export-led developmental space to technology-oriented developmental space. In this context, this paper aims to identify the characteristics of technology-oriented space by investigating intra-, inter- and extra-firms relations of Korean FDI firms in Shanghai, China. In terms of intra-firm relations, Korean FDI firms adopted strategies for maximizing business efficiency and effectiveness by transforming their personal networks into formal networks. In terms of inter-firm relations, the distinction of Korean FDI firms' networks has been found in accordance with firm size, industrial sectors, ways of investment etc. Finally, Korean FDI firms has formal networks resulted from institutional involvement, as well as informal (personal) networks based on guanxi (inter-personal relations) in extra-firm relations. Therefore, two types of processes affecting the networks and institutional legacies of the Soviet system can be identified. First is the interaction of institutions and restructuring of pre-existing networks. Second is the insulated institutions and endurance of preexisting networks. And these two governance types have created regional economies which are embedded and over-embedded.

• Journal of Labour Economics
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• v.26 no.3
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• pp.209-230
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• 2003

This study investigates the factors affecting job seekers' utilization of social networks in Korean job markets by using the East Asia Social Survey on People's Work Life: South Korea data collected in 1996. If employees are analyzed as a whole, social networks have been used more frequently than formal means and direct application. Results of the multinomial logistic regression largely show that job seekers who occupy better positions in job markets have used social networks less frequently. This is due to the characteristics of Korean job markets: (1) Korean job markets are clearly divided by several criteria, and (2) in the sectors of job markets which provide better socioeconomic rewards, the competition through formal means is the main path of getting jobs.

• International Journal of Railway
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• v.5 no.2
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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.

• Convergence Security Journal
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• v.12 no.1
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• pp.27-33
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• 2012

VANET(Vehicular Ad-hoc Network) is a kind of ad hoc networks consist of intelligence vehicular ad nodes, and has become a hot emerging research project in many fields. It provide traffic safety, cooperative driving and etc. but has also some security problems that can be occurred in general ad hoc networks. Also, in VANET, vehiculars sho uld be able to authenticate each other to securely communicate with network-based infrastructure, and their location s and identifiers should not be exposed from the communication messages. This paper explains V2I authentication pr otocol using a hash function that preserves the user privacy. In addition, we analyze the security stability of the V2I authentication protocol using Casper in the formal verification technique. As a result, V2I authentication protocol us ing hash function prove a stability.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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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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• v.19 no.2
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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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• v.4 no.2
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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.

• Proceedings of the IEEK Conference
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• 2002.06c
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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.