• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.5
• /
• pp.581-588
• /
• 2019

In this paper, I propose an modified back-off algorithm to improve the fairness for slotted ALOHA sensor networks. In hierarchical networks, the performance degradation of a specific node can cause degradation of the overall network performance in case the data transmitted by lower nodes is needed to be synthesized and processed by an upper node. Therefore it is important to ensure the fairness of transmission performance to all nodes. The proposed scheme choose a back-off time of a node considering the previous transmission results as well as the current transmission result. Moreover a node that failed to transmit consecutively is given gradually shorter back-off time but a node that is success to transmit consecutively is given gradually longer back-off time. Through simulations, I compare and analyze the performance of the proposed scheme with the binary exponential back-off algorithm(BEB). The results show that the proposed scheme reduces the throughput slightly compared to BEB but improves the fairness significantly.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.4
• /
• pp.1317-1341
• /
• 2021

Nowadays, the Internet of Things (IoT) is adopted to enable effective and smooth communication among different networks. In some specific application, the Wireless Sensor Networks (WSN) are used in IoT to gather peculiar data without the interaction of human. The WSNs are self-organizing in nature, so it mostly prefer multi-hop data forwarding. Thus to achieve better communication, a cross-layer routing strategy is preferred. In the cross-layer routing strategy, the routing processed through three layers such as transport, data link, and physical layer. Even though effective communication achieved via a cross-layer routing strategy, energy is another constraint in WSN assisted IoT. Cluster-based communication is one of the most used strategies for effectively preserving energy in WSN routing. This paper proposes a Bio-inspired cross-layer routing (BiHCLR) protocol to achieve effective and energy preserving routing in WSN assisted IoT. Initially, the deployed sensor nodes are arranged in the form of a grid as per the grid-based routing strategy. Then to enable energy preservation in BiHCLR, the fuzzy logic approach is executed to select the Cluster Head (CH) for every cell of the grid. Then a hybrid bio-inspired algorithm is used to select the routing path. The hybrid algorithm combines moth search and Salp Swarm optimization techniques. The performance of the proposed BiHCLR is evaluated based on the Quality of Service (QoS) analysis in terms of Packet loss, error bit rate, transmission delay, lifetime of network, buffer occupancy and throughput. Then these performances are validated based on comparison with conventional routing strategies like Fuzzy-rule-based Energy Efficient Clustering and Immune-Inspired Routing (FEEC-IIR), Neuro-Fuzzy- Emperor Penguin Optimization (NF-EPO), Fuzzy Reinforcement Learning-based Data Gathering (FRLDG) and Hierarchical Energy Efficient Data gathering (HEED). Ultimately the performance of the proposed BiHCLR outperforms all other conventional techniques.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.2
• /
• pp.285-289
• /
• 2020

The configuration of hierarchical wireless networks is provided to support diverse network environments. In the base station, two system state can be basically considered for the operation management so that the state transition may be occurred between active and sleep modes. Hence, to reduce energy consumption the system operation management of the low power should be considered to the base station system. In this paper we consider the analytical model of Discontinuous Reception (DRX) to investigate the system management. We provide the analysis scheme of base station system by the DRX model, and the low power factor would be investigated for the energy consumption. We also use the finite-state Markov system model that in a system state period the wireless resource request and the operation of service call arrival interval is considered to numerically analyze the performance of energy saving operations of base station.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.7
• /
• pp.1060-1070
• /
• 2022

With the development of information technology, the size of the system has become larger and diversified, and the existing role-based access control has faced limitations. Blockchain technology is being used in various fields by presenting new solutions to existing security vulnerabilities. This paper suggests efficient role-based access control in a blockchain where the required gas and processing time vary depending on the access frequency and capacity of the storage. The proposed method redefines the role of reusable units, introduces a hierarchical structure that can efficiently reflect dynamic states to enhance efficiency and scalability, and includes user-centered authentication functions to enable cryptocurrency linkage. The proposed model was theoretically verified using Markov chain, implemented in Ethereum private network, and compared experiments on representative functions were conducted to verify the time and gas efficiency required for user addition and transaction registration. Based on this in the future, structural expansion and experiments are required in consideration of exception situations.

• Korean Journal of Culture and Social Issue
• /
• v.19 no.3
• /
• pp.457-485
• /
• 2013

This study attempted to discover the dimensions of Korean culture, with the presumption that the cross-cultural studies(Hofstede, 1980, 1997; Schwartz, 1992, 1994; Trompenaars and Hampden-Turner, 1997; House et al., 2004) have limitation to explain non-western culture including Korean culture. Even though there are some Korean cultural studies, they used heuristic approaches applying the authors' experiences and intuitions. This study applied the Cultural Consensus Theory to overcome the previous studies' shortcomings and to discover the dimensions that can be empirically proved by data. In specific this study conducted in-depth interview, used content analysis, did frequency analysis, and applied pilesort technique, multidimensional scaling and network analysis. As a result, this study obtained five categories: public self-consciousness, group-focused orientation, affective human relations, hierarchical culture, and result-orientation. It is expected that these dimensions can be used as important variables that may explain Korean social phenomena.

• Korean Journal of Culture and Social Issue
• /
• v.15 no.4
• /
• pp.565-589
• /
• 2009

The present study explored the major components of adaptive game behavior among adolescents in Korea. Based on relevant research and a pilot testing, an Adaptive Game Use Scale (AGUS) was developed and validated. A stratified sampling procedure was used to draw a representative sample, and a total of 600 male and female students from middle schools and high schools in various regions participated in the study. Factor analyses revealed 7 facets of adaptive game behavior, including experiencing vitality, expanding life experience, making good use of leisure time, experiencing flow, exercising control, experiencing self-esteem, maintaining and expanding social network. Internal consistency and temporal stability(4 weeks) of the scale were both high. A confirmatory factor analysis indicated that a 7-factor hierarchical model fits well with the data. Moreover, additional analyses suggested that AGUS and game addiction are conceptually distinct. Correlational analyses also indicated that AGUS has good discriminant validity and concurrent validity. Implications of the findings and future directions were discussed.

• Asia pacific journal of information systems
• /
• v.34 no.1
• /
• pp.150-190
• /
• 2024

This article proposes a framework to elucidate the structural dynamics of the generative AI ecosystem. It also outlines the practical application of this proposed framework through illustrative policies, with a specific emphasis on the development of the Korean generative AI ecosystem and its implications of platform strategies at AI platform-squared. We propose a comprehensive classification scheme within generative AI ecosystems, including app builders, technology partners, app stores, foundational AI models operating as operating systems, cloud services, and chip manufacturers. The market competitiveness for both app builders and technology partners will be highly contingent on their ability to effectively navigate the customer decision journey (CDJ) while offering localized services that fill the gaps left by foundational models. The strategically important platform of platforms in the generative AI ecosystem (i.e., AI platform-squared) is constituted by app stores, foundational AIs as operating systems, and cloud services. A few companies, primarily in the U.S. and China, are projected to dominate this AI platform squared, and consequently, they are likely to become the primary targets of non-market strategies by diverse governments and communities. Korea still has chances in AI platform-squared, but the window of opportunities is narrowing. A cautious approach is necessary when considering potential regulations for domestic large AI models and platforms. Hastily importing foreign regulatory frameworks and non-market strategies, such as those from Europe, could overlook the essential hierarchical structure that our framework underscores. Our study suggests a clear strategic pathway for Korea to emerge as a generative AI powerhouse. As one of the few countries boasting significant companies within the foundational AI models (which need to collaborate with each other) and chip manufacturing sectors, it is vital for Korea to leverage its unique position and strategically penetrate the platform-squared segment-app stores, operating systems, and cloud services. Given the potential network effects and winner-takes-all dynamics in AI platform-squared, this endeavor is of immediate urgency. To facilitate this transition, it is recommended that the government implement promotional policies that strategically nurture these AI platform-squared, rather than restrict them through regulations and stakeholder pressures.

• Journal of the Korea Society of Computer and Information
• /
• v.29 no.1
• /
• pp.111-119
• /
• 2024

In this paper, we propose a big data platform that can collect information from various sources collected at ocean. Currently operating ocean-related big data platforms are focused on storing and sharing created data, and each data provider is responsible for data collection and preprocessing. There are high costs and inefficiencies in collecting and integrating data in a marine environment using communication networks that are poor compared to those on land, making it difficult to implement related infrastructure. In particular, in fields that require real-time data collection and analysis, such as weather information, radar and sensor data, a number of issues must be considered compared to land-based systems, such as data security, characteristics of organizations and ships, and data collection costs, in addition to communication network issues. First, this paper defines these problems and presents solutions. In order to design a big data platform that reflects this, we first propose a data source, hierarchical MEC, and data flow structure, and then present an overall platform structure that integrates them all.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.7
• /
• pp.1986-2009
• /
• 2024

The integration of blockchain technology with the rapid growth of Internet of Things (IoT) devices has enabled secure and decentralised data exchange. However, security vulnerabilities and performance limitations remain significant challenges in IoT blockchain networks. This work proposes a novel approach that combines transaction representation and machine learning techniques to address these challenges. Various clustering techniques, including k-means, DBSCAN, Gaussian Mixture Models (GMM), and Hierarchical clustering, were employed to effectively group unlabelled transaction data based on their intrinsic characteristics. Anomaly transaction prediction models based on classifiers were then developed using the labelled data. Performance metrics such as accuracy, precision, recall, and F1-measure were used to identify the minority class representing specious transactions or security threats. The classifiers were also evaluated on their performance using balanced and unbalanced data. Compared to unbalanced data, balanced data resulted in an overall average improvement of approximately 15.85% in accuracy, 88.76% in precision, 60% in recall, and 74.36% in F1-score. This demonstrates the effectiveness of each classifier as a robust classifier with consistently better predictive performance across various evaluation metrics. Moreover, the k-means and GMM clustering techniques outperformed other techniques in identifying security threats, underscoring the importance of appropriate feature selection and clustering methods. The findings have practical implications for reinforcing security and efficiency in real-world IoT blockchain networks, paving the way for future investigations and advancements.

• Journal of Forest and Environmental Science
• /
• v.40 no.3
• /
• pp.210-226
• /
• 2024

Old-growth mixed-conifer forests in Bhutan are characterized by remarkable tree species compositional heterogeneity. However, our knowledge of tree species assemblages and their structural attributes in these forests has been limited. Therefore, forest classification has been reliant on a single dominant species. This study aimed to distinguish tree species assemblages in an old-growth mixed conifer forest in Western Bhutan and to describe their natural compositional and stand structural characteristics. Furthermore, the regeneration status of species was investigated and the quantity and quality of accumulated coarse woody debris were assessed. Ninety simple random sampling plots were surveyed in the study site between 3,000 and 3,600 meters above sea level. Tree, standing deadwood, regeneration, and coarse woody debris data were collected. Seven tree species assemblages were distinguished by Hierarchical Cluster Analysis and Indicator Species Analysis, representing five previously undescribed tree species associations with unique set of consistent species. Principal Component Analysis revealed two transitional pathways of species dominance along an altitudinal gradient, highly determined by relative topographic position. The level of stand stratification varied within a very wide range, corresponding to physiognomic composition. Rotated-sigmoid and negative exponential diameter distributions were formed by overstorey species with modal, and understorey species with negative exponential distribution. Overstorey dominant species showed extreme nurse log dependence during regeneration, which supports the formation of their modal distribution by an early natural selection process. This allows the coexistence of overstorey and understorey dominant species, increasing the sensitivity of these primary ecosystems to forest management.