There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Pattern Recognition and Machine Learning

What is Twitter

The blooming trend of smart grid deployment is engaged by the evolution of the network technology, as the connected environment offers various alternatives for electrical data collections. Having diverse data sharing/transfer means is deemed an important aspect in enabling intelligent controls/governance in smart grid. However, security and privacy concerns also are introduced while flexible communication services are provided, such as energy depletion and infrastructure mapping attacks. This paper proposes a model permissioned blockchain edge model for smart grid network (PBEM-SGN) to address the two significant issues in smart grid, privacy protections, and energy security, by means of combining blockchain and edge computing techniques. We use group signatures and covert channel authorization techniques to guarantee users’ validity. An optimal security-aware strategy is constructed by smart contracts running on the blockchain. Our experiments have evaluated the effectiveness of the proposed approach.

Permissioned Blockchain and Edge Computing Empowered Privacy-Preserving Smart Grid Networks

Subsequently, an agreement on technical co-operation between ISO and CEN was approved by the ISO Council resolution 18/1990 and the CEN General Assembly resolution 3/1990. This agreement (called the Vienna Agreement) was published in June 1991. It is accompanied by common ISO-CEN “Guidelines for the TC/SC Chairmen and Secretariats for implementation”, approved in 1992 and revised in September 1998.

International Organization for Standardization (ISO)

The rapid growth of social network services has produced a considerable amount of data, called big social data. Big social data are helpful for improving personalized recommender systems because these enormous data have various characteristics. Therefore, many personalized recommender systems based on big social data have been proposed, in particular models that use people relationship information. However, most existing studies have provided recommendations on special purpose and single-domain SNS that have a set of users with similar tastes, such as MovieLens and Last.fm; nonetheless, they have considered closeness relation. In this paper, we introduce an appropriate measure to calculate the closeness between users in a social circle, namely, the friendship strength. Further, we propose a friendship strength-based personalized recommender system that recommends topics or interests users might have in order to analyze big social data, using Twitter in particular. The proposed measure provides precise recommendations in multi-domain environments that have various topics. We evaluated the proposed system using one month's Twitter data based on various evaluation metrics. Our experimental results show that our personalized recommender system outperforms the baseline systems, and friendship strength is of great importance in personalized recommendation.

Personalized recommender system based on friendship strength in social network services

Cloud-based electronic health record (EHR) systems enable medical documents to be exchanged between medical institutions; this is expected to contribute to improvements in various medical services in the future. However, as the system architecture becomes more complicated, cloud-based EHR systems may introduce additional security threats when compared with the existing singular systems. Thus, patients may experience exposure of private data that they do not wish to disclose. In order to protect the privacy of patients, many approaches have been proposed to provide access control to patient documents when providing health services. However, most current systems do not support fine-grained access control or take into account additional security factors such as encryption and digital signatures. In this paper, we propose a cloud-based EHR model that performs attribute-based access control using extensible access control markup language. Our EHR model, focused on security, performs partial encryption and uses electronic signatures when a patient’s document is sent to a document requester. We use XML encryption and XML digital signature technology. Our proposed model works efficiently by sending only the necessary information to the requesters who are authorized to treat the patient in question.

Privacy-Preserving Attribute-Based Access Control Model for XML-Based Electronic Health Record System

Recently, there has been an increase in studies relating to the Internet of Things (IoT) in various fields, such as smart cities, smart homes, smart factories, and healthcare. In an IoT environment, several entities, including users, devices, and information resources, are interconnected and interworked with services. Therefore, interoperability between different entities is essential to accomplish the goals of IoT systems. Further, security is another important aspect to achieve in an IoT environment to protect information resources and privacy when networking between different entities. Therefore, security and interoperability may be significant barriers in the implementation of IoT in the real world. Several studies have been conducted to investigate methods for accomplishing interoperability and security in IoT, but they address only specific problems. Hence, compatibility and generality must be considered to accomplish the goals of IoT systems. International standards provide general methods by listing protocols, rules, guidelines, and characteristics that are defined and approved by authorized organizations, helping develop and manage systems efficiently by applying these standards; interoperability and security are supported by adopting standards in development and management. Therefore, the adoption of international standards is required to overcome the barriers in IoT. Furthermore, international standard organizations are developing IoT-related standards that may provide a solution to interoperability and security. However, a study focusing on interoperability- and security-related standards has not yet been conducted. Therefore, in this paper, we focus on international standards related to interoperability and security for IoT environments. Moreover, we studied international standard organizations that have been developing standards for IoT. In this study, a systematic literature review is conducted, and international standards are analyzed. In addition, any remaining challenges related to interoperability and security for IoT standards are discussed.

A Survey on Standards for Interoperability and Security in the Internet of Things

The goal of a group recommendation involves providing appropriate information for all members in a group. Most extant studies use aggregation methods to determine group preferences. An aggregation method is an approach that aggregates individual preferences of group members to recommend items to a group. Previous studies on aggregation methods only consider high averages, counts, and rankings to provide recommendations. However, the most important component of a group recommendation involves ensuring that majority of the members in a group are satisfied with the recommended results. Therefore, it is necessary to consider the deviation as an important element in aggregation methods. The present study involves proposing an upward leveling (UL) aggregation method that considers deviations for group recommendations. The UL recommends items with low deviations and high averages in conjunction with frequency of positive rating counts for group members. Furthermore, the effectiveness of the UL is validated to perform a comparative evaluation with existing aggregation methods by using the normalized discounted cumulative gain (NDCG) and diversity. The results indicate that the UL outperforms all the baselines and that the deviation plays an important role in the aggregation method.

An enhanced aggregation method considering deviations for a group recommendation

As WSNs combine with a diversity of next-generation technologies, wireless sensor networks (WSNs) have gained considerable attention as a promising ubiquitous technology. Even though several studies on WSNs are being undertaken, few systematically analyze the security issues relating to them. Moreover, recent systems tend to be implemented without sufficient consideration about owns security requirements, which can lead to lethal threats. Systems that do not consider security requirements may provide attackers the opportunity to reduce the overall efficiency and performance of the system. This means that inadequately applied security requirements can result in defective security of systems. Therefore, in this study, we emphasized the importance of security requirements to raise awareness regarding them. In addition, we analyzed literature that could be improved by including WSNs security requirements such as characteristics, constraints, and threats. Furthermore, we adopted a systematic methodology by referring to reliable literature and performed a different analysis from previous studies. We derived and mapped the different security factors based on the literature and illustrated the relationships of each security factor. Finally, our research compared with studies of a similar type to evaluate whether it provided a significant contribution. In other words, in this study, we analyzed various factors related to WSNs security based on reviewing the literature and show our contribution, such as a systematic analysis framework and factor mapping compared with traditional studies. Though there are some considerations, we expect that this research derived the essential security requirements in any WSNs environments.

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Euijong Lee

Papers

Personalized recommender system based on friendship strength in social network services

Privacy-Preserving Attribute-Based Access Control Model for XML-Based Electronic Health Record System

A Survey on Standards for Interoperability and Security in the Internet of Things

An enhanced aggregation method considering deviations for a group recommendation

A Survey on Security Requirements for WSNs: Focusing on the Characteristics Related to Security