• Journal of Science and Technology Studies
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• v.17 no.2
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• pp.81-111
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• 2017

In this paper, I focus on the performativity thesis introduced and developed by Science and Technology Studies (STS) scholars such as Callon, MacKenzie, etc. since the mid 1990s. The performativity thesis was discussed in economic sociology by STS scholars has been pervaded to other research areas including general economics, accounting, finance and so on. The main idea of the thesis is that economic theories perform, shape, and format economy rather than just describe economy. I show that the thesis is based on the traditional STS ideas such as performativity derived from Merton's self-fulfilling prophecy and the actor-network theory. Although the thesis has been criticised by various researchers from both inside and outside STS, it has provided meaningful implications for understanding economic phenomenon from a viewpoint of STS. Furthermore, reflexive researches for performativity of STS theories can be discussed in the next stage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.833-839
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• 2010

Mobility of sensor node is one of the rising issues in Wireless Sensor Networks (WSN). However, current security researches on WSN only consider static environments. Thus they are not sufficient to be deployed in the dynamic environment where the resource is limited. In this paper, we propose the efficient node authentication and key exchange protocol that reduces the overhead in node re-authentication.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.29-36
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• 2022

Smart grid (SG) software platforms and communication networks that run and manage the entire grid are increasingly concerned about cyber security. Characteristics of the smart grid networks, including heterogeneity, time restrictions, bandwidth, scalability, and other factors make it difficult to secure. The age-old strategy of "building bigger walls" is no longer sufficient given the rise in the quantity and size of cyberattacks as well as the sophisticated methods threat actor uses to hide their actions. Cyber security experts utilize technologies and procedures to defend IT systems and data from intruders. The primary objective of every organization's cybersecurity team is to safeguard data and information technology (IT) infrastructure. Consequently, further research is required to create guidelines and methods that are compatible with smart grid security. In this study, we have discussed objectives of of smart grid security, challenges of smart grid security, defensive cybersecurity techniques, offensive cybersecurity techniques and open research challenges of cybersecurity.

• Journal of the Korean association of regional geographers
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• v.23 no.1
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• pp.1-22
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• 2017

This paper is to consider conceptually a formation of food-networks and border-crossing of transnational marriage migrant households on the basis of actor-network theory, and to analyze empirical data on the issues collected by interview with marriage migrant women living around Daegu, S.Korea. Some research results can be argued as follows: First, food can be seen, not as a single material object, but as a multiple and hybrid network of human and nonhuman (material and institutional) actors, in which activities of food cooking and eating are regulated by and (re)construct social relations and placeness of households. Secondly, food-networks in marriage migrant households implement relationships of micro-power (and attachment) in the process of its (re)formation, and hence the food-network, it can be argued, is a field of power in which conflicts and compromising around food cooking and eating are intersecting each others. Thirdly, food-networks in marriage migrant households in both their origin country and in the Korean home are not only affected by macro natural and social environments but also by micro placeness of the households, both of which constitute the food-networks and operate in relations with other actors in the netwroks. Finally, food-networks in marriage migrant households reflect multiple and multi-scalar spatial mobility and placeness of transnational food culture, through which they express topologically 'fluid space' and 'absent presence', in which marriage migrant women can (or cannot) conduct social and cultural border-crossing.

• ETRI Journal
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• v.43 no.3
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• pp.414-426
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• 2021

In the task of data routing in Internet of Things enabled volatile underwater environments, providing better transmission and maximizing network communication performance are always challenging. Many network issues such as void holes and network isolation occur because of long routing distances between nodes. Void holes usually occur around the sink because nodes die early due to the high energy consumed to forward packets sent and received from other nodes. These void holes are a major challenge for I-UWSANs and cause high end-to-end delay, data packet loss, and energy consumption. They also affect the data delivery ratio. Hence, this paper presents an energy efficient watchman based flooding algorithm to address void holes. First, the proposed technique is formally verified by the Z-Eves toolbox to ensure its validity and correctness. Second, simulation is used to evaluate the energy consumption, packet loss, packet delivery ratio, and throughput of the network. The results are compared with well-known algorithms like energy-aware scalable reliable and void-hole mitigation routing and angle based flooding. The extensive results show that the proposed algorithm performs better than the benchmark techniques.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.5
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• pp.297-307
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• 2022

The simple procedural segment selection algorithm commonly used in Dynamic Adaptive Streaming over HTTP (DASH) reveals severe weakness to provide high-quality streaming services in the integrated mobile networks of various wired and wireless links. A major issue could be how to properly cope with dynamically changing underlying network conditions. The key to meet it should be to make the segment selection algorithm much more adaptive to fluctuation of network traffics. This paper presents a system architecture that replaces the existing procedural segment selection algorithm with a deep reinforcement learning algorithm based on the Asynchronous Advantage Actor-Critic (A3C). The distributed A3C-based deep learning server is designed and implemented to allow multiple clients in different network conditions to stream videos simultaneously, collect learning data quickly, and learn asynchronously, resulting in greatly improved learning speed as the number of video clients increases. The performance analysis shows that the proposed algorithm outperforms both the conventional DASH algorithm and the Deep Q-Network algorithm in terms of the user's quality of experience and the speed of deep learning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.620-636
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• 2015

Survivability is a necessary property of network system in disturbed environment. Recovery ability is a key actor of survivability. This paper concludes network survivability into a novel composite metric, i.e. Network Recovery Degree (NRD). In order to measure this metric in quantity, a concept of Source-Destination Pair (SD Pair), is created to abstract end-to-end activity based on end nodes in network, and the quality of SD Pair is also used to describe network performance, such as connectivity, quality of service, link degree, and so on. After that, a Survivability Test method in large scale Network based on SD pairs, called STNSD, is provided. How to select SD Pairs effectively in large scale network is also provided. We set up simulation environment to validate the test method in a severe destroy scenario and evaluate the method scalability in different large scale network scenarios. Experiment and analysis shows that the metric NRD correctly reflects the effort of different survivability strategy, and the proposed test method STNSD has good scalability and can be used to test and evaluate quantitative survivability in large scale network.

• Journal of Information Technology Services
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• v.16 no.3
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• pp.167-183
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• 2017

The rapid growth of information technology and mobile service platforms, i.e., internet, google, and facebook, etc. has led the abundance of data. Due to this environment, the world is now facing a revolution in the process that data is searched, collected, stored, and shared. Abundance of data gives us several opportunities to knowledge discovery and data mining techniques. In recent years, data mining methods as a solution to discovery and extraction of available knowledge in database has been more popular in e-commerce service fields such as, in particular, movie recommendation. However, most of the classification approaches for predicting the movie popularity have used only several types of information of the movie such as actor, director, rating score, language and countries etc. In this study, we propose a classification-based support vector machine (SVM) model for predicting the movie popularity based on movie's genre data and social network data. Social network analysis (SNA) is used for improving the classification accuracy. This study builds the movies' network (one mode network) based on initial data which is a two mode network as user-to-movie network. For the proposed method we computed degree centrality, betweenness centrality, closeness centrality, and eigenvector centrality as centrality measures in movie's network. Those four centrality values and movies' genre data were used to classify the movie popularity in this study. The logistic regression, neural network, $na{\ddot{i}}ve$ Bayes classifier, and decision tree as benchmarking models for movie popularity classification were also used for comparison with the performance of our proposed model. To assess the classifier's performance accuracy this study used MovieLens data as an open database. Our empirical results indicate that our proposed model with movie's genre and centrality data has by approximately 0% higher accuracy than other classification models with only movie's genre data. The implications of our results show that our proposed model can be used for improving movie popularity classification accuracy.

• Journal of the Economic Geographical Society of Korea
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• v.24 no.3
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• pp.259-282
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• 2021

This study analyzes actor networks in regional innovation processes with a focus on actors' activities and finds the determinants of the networks, thereby aiming to provide information useful for regional innovation policy makers. To this end, the study conducted a social network analysis of the national R&D projects data and identified the activities of innovation actors. Finding out the network determinants was QAP analysis. The study suggests three main findings as follows. First, a meaningful difference exists in characteristics of innovation activity by region. Second, the network of innovation actors meaningfully differs from region to region. The centrality of the network was found to be high in universities and businesses in Seoul and Gyeonggi, and in public research institutes in Daejeon. There are regions where all the networks of innovative actors are composed of one component, while some regions are not yet established with the network. Finally, although the networks of innovation actors are influenced by the geographical proximity and the size of the R&D fund, it is notable that the previous continuous relationship forms a strong research network.

• Journal of the Korean association of regional geographers
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• v.12 no.2
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• pp.245-264
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• 2006

According to many conceptual researches and discourses, development of information-communication technology(ICT) has made great influences upon activities on time and space. But some empirical studies have shown that its influence in the real world is not so great as we may expect In order to avoid these two oppositional views, this paper wants to put interests on socio-spatial relationships or networks, rather than individual phenomena or consciousness, which have been transformed under the influence of ICT. The development of ICT presupposes a creation of information network, and hence the term 'etwork social space' can be used to see its spatial influence, which would be further understood with the theory of actor-network. This paper also suggests that network social space has three strata, that is, 'nstant' 'unctional 'and 'aterial' and that network social space can be emphasized not only as newly emerging social space but also as reconstruction of subjects' identity through his/her participation into information network as its node.