• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.58-73
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• 2021

Cloud Service Providers (CSPs) enable their users to access Cloud computing and storage services from anywhere in quick and flexible manners through the Internet. With the basis of 'pay-as-you-go' model, it makes the interactions between CSPs and the users play a vital role in shaping the Cloud computing market. A pool of virtualized and dynamically scalable Cloud services that delivered on demand to the users is associated with guaranteed performance and cost-provisioning. It needed a costing scheme for determining suitable charges in order to secure lease pricing of the Cloud services. However, it is hard to meet the satisfied prices for both CSPs and users due to their conflicting needs. Furthermore, there is lack of Service Level Agreements (SLAs) that allowing the users to take part into price negotiating process. The users may lose their interest to use Cloud services while reducing CSPs profit. Therefore, this paper proposes a generic costing scheme for Cloud services using General Equilibrium Theory (GET). GET helps to formulate the price function for various services' factors to match with various demands from the users. It is initially determined by identifying the market circumstances that a general equilibrium will be hold and reached. Specifically, there are two procedures of agreement made in response to (i) established equilibrium supply and demand, and (ii) service price formed and constructed in a price range. The SLAs in our costing scheme is integrated to satisfy both CSPs and users' needs while minimizing their conflicts. The price ranging strategy is deliberated to provide prices' options to the users with respect their budget limit. Meanwhile, the CSPs can adaptively charge based on users' preferences without losing their profit. The costing scheme is testable and analyzed in multi-tenant computing environments. The results from our simulation experiments demonstrate that the proposed costing scheme provides better users' satisfaction while fostering fairness pricing in the Cloud market.

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.174-181
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• 2004

Objective : To examine the association between dietary factors and cognitive impairment in older Korean women living in the community. Methods : Wave 2 data, from the Suwon Longitudinal Aging Study (SLAS), of 365 women aged 65 years or over, were used. The Korean version of the 30-point Mini-Mental State Examination (MMSE-K) was used to assess cognitive impairment (score$\geq$19). Dietary habits and frequencies of food group consumption were also examined. Results : A total of 67 women (18.4%) were found to be cognitively impaired. In bivariate analyses, nondietary factors, such as age, marital status, education, income, self-rated health, depression, emotional support, social activity, exercise, and dietary factors, such as self-rated nutritional status, frequency of beans and bean products and milk and dairy products consumption were associated with cognitive impairment. In the multivariate analysis, a higher frequency ($\geq$1 vs. <1 time/day) of beans and bean products (OR=0.48, 95% CI: 0.23-0.99) and milk and dairy products (OR=0.25, 95% CI: 0.10-0.61) consumption was inversely associated with cognitive impairment, after adjustment for non-dietary factors. Conclusion : These results suggest that dietary factors may play a significant role in cognitive impairment of older Korean women.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.241-252
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• 2006

Traditional service-level agreements (SLAs), defined by average delay or packet loss, often camouflage the instantaneous performance perceived by end-users. We define a set of metrics for service availability to quantify the performance of Internet protocol (IP) backbone networks and capture the impact of routing dynamics on packet forwarding. Given a network topology and its link weights, we propose a novel technique to compute the associated service availability by taking into account transient routing dynamics and operational conditions, such as border gateway protocol (BGP) table size and traffic distributions. Even though there are numerous models for characterizing topologies, none of them provide insights on the expected performance perceived by end customers. Our simulations show that the amount of service disruption experienced by similar networks (i.e., with similar intrinsic properties such as average out-degree or network diameter) could be significantly different, making it imperative to use new metrics for characterizing networks. In the second part of the paper, we derive goodness factors based on service availability viewed from three perspectives: Ingress node (from one node to many destinations), link (traffic traversing a link), and network-wide (across all source-destination pairs). We show how goodness factors can be used in various applications and describe our numerical results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4640-4661
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• 2018

To cope with the explosive growth of Internet services, Service Function Chaining (SFC) based on Software-defined Networking (SDN) is an emerging and promising technology that has been suggested to meet this challenge. Determining the placement of Virtual Network Functions (VNFs) and routing paths that optimize the network utilization and resource consumption is a challenging problem, particularly without violating service level agreements (SLAs). This problem is called the optimal SFC placement problem and an Integer Linear Programming (ILP) formulation is provided. A greedy heuristic solution is also provided based on an improved two-step mapping algorithm. The obtained experimental results show that the proposed algorithm can automatically place VNFs at the optimal locations and find the optimal routing paths for each online request. This algorithm can increase the average request acceptance rate by about 17.6% and provide more than 20-fold reduction of the computational complexity compared to the Greedy algorithm. The feasibility of this approach is demonstrated via NetFPGA-10G prototype implementation.

• Journal of Information Technology Services
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• v.7 no.1
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• pp.151-166
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• 2008

The Outsourcing Industry has grown at a swift pace and evolved over time, and the Global IT Outsourcing market has shown signs of a steady growth. In the Korean financial industry, however, IT Outsourcing is not active as that of the advanced countries and there is lack of literature to understand the characteristics of IT Outsourcing in the financial industry. This paper, therefore, analyze the outcomes surveying 40 financial companies in Korea to investigate how IT Outsourcing risk factors affects IT Outsourcing intention. Based on our literature reviews based on number of key articles, journals, and the focus group interviews, IT Outsourcing risk factors are proposed into four different domains: Transaction, Client, Vendor and Environmental perspective. It found that two risk factors (Client and Environmental perspective) are closely related to the IT Outsourcing intention of the Korean financial industry. Finally, this paper concludes that concrete SLAs (Service Level Agreements) of the clients and support of government agencies are important to mitigate the IT Outsourcing risks.

• Journal of Preventive Medicine and Public Health
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• v.40 no.2
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• pp.137-144
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• 2007

Objectives : According to Rowe and Kahn (1998), successful aging is the combination of a low probability of disease, high functioning, and active engagement with life. The purpose of this study was to assess the relationship between active engagement with life and functioning among the community-dwelling elderly. Methods : Data were collected from Wave 2 of the Suwon Longitudinal Aging Study (SLAS), consisting of a sample of 645 persons aged 65 and older living in the community. A social activity checklist and social support inventory were used as measures of engagement with life, along with the Physical Functioning (PF) scale as a measure of functioning. The effects of social support and social activity on physical functioning, taking into account the covariates, were analyzed by hierarchical linear regression analysis. Results : Maintenance of social activity and social support were significantly associated with higher physical function, after adjusting for sociodemographic and health-related covariates. Social support appeared to be more prominent than social activity in predicting physical functioning. Conclusions : Social support and social activity are potentially modifiable factors associated with physical function in older persons. Studies examining the role social engagement may play in preventing disability are warranted.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.3003-3029
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• 2023

The rapid evolution of the IoT has paved the way for new opportunities in smart city domains, including e-health, smart homes, and precision agriculture. However, this proliferation of services demands effective SLAs between customers and service providers, especially for critical services. Difficulties arise in maintaining the integrity of such agreements, especially in vulnerable wireless environments. This study proposes a novel SLA management model that uses an SDN-Enabled WSN consisting of wireless nodes to interact with smart contracts in a straightforward manner. The proposed model ensures the persistence of network metrics and SLA provisions through smart contracts, eliminating the need for intermediaries to audit payment and compensation procedures. The reliability and verifiability of the data prevents doubts from the contracting parties. To meet the high-performance requirements of the blockchain in the proposed model, low-cost algorithms have been developed for implementing blockchain technology in wireless sensor networks with low-energy and low-capacity nodes. Furthermore, a cryptographic signature control code is generated by wireless nodes using the in-memory private key and the dynamic random key from the smart contract at runtime to prevent tampering with data transmitted over the network. This control code enables the verification of end-to-end data signatures. The efficient generation of dynamic keys at runtime is ensured by the flexible and high-performance infrastructure of the SDN architecture.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.4
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• pp.763-777
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• 2021

Information security started as an IT operation process and is now recognized as an important issue of information technology, and each international organization is newly defining the concept. Information security itself is a new combination of IT technologies, a set of technologies and a technology area. As IT outsourcing becomes common in many public sectors, SLAs are introduced to evaluate the level of IT services. In the area of information security, many studies have been conducted on the derivation and selection of SLA performance indicators, but it is difficult to find a way to apply the performance indicators to service level evaluation and performance systems. This thesis conducted a study on the application of a service evaluation system for information security performance indicators based on the public sector and a performance system including compensation regulations. It presents standards and rewards(incentive and penalty) that define expectation and targets of performance indicators that take into account the environment and characteristics of a specific public sector, and defines appropriate SLA costs. It proposes a change plan for the organizational structure for practical SLA application and service level improvement.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.23-28
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• 2024

The multi-tenancy and high scalability of the cloud have inspired businesses and organizations across various sectors to adopt and deploy cloud computing. Cloud computing provides cost-effective, reliable, and convenient access to pooled resources, including storage, servers, and networking. Cloud service models, SaaS, PaaS, and IaaS, enable organizations, developers, and end users to access resources, develop and deploy applications, and provide access to pooled computing infrastructure. Despite the benefits, cloud service models are vulnerable to multiple security and privacy attacks and threats. The SaaS layer is on top of the PaaS, and the IaaS is the bottom layer of the model. The software is hosted by a platform offered as a service through an infrastructure provided by a cloud computing provider. The Hypertext Transfer Protocol (HTTP) delivers cloud-based apps through a web browser. The stateless nature of HTTP facilitates session hijacking and related attacks. The Open Web Applications Security Project identifies web apps' most critical security risks as SQL injections, cross-site scripting, sensitive data leakage, lack of functional access control, and broken authentication. The systematic literature review reveals that data security, application-level security, and authentication are the primary security threats in the SaaS model. The recommended solutions to enhance security in SaaS include Elliptic-curve cryptography and Identity-based encryption. Integration and security challenges in PaaS and IaaS can be effectively addressed using well-defined APIs, implementing Service Level Agreements (SLAs), and standard syntax for cloud provisioning.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.9-16
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• 2005

A new online routing algerian is proposed in this paper, which use the interference-prediction to solve the network congestion originated from extension of Internet scope and increasing amount of traffic. The end-to-end QoS has to be guaranteed in order to satisfy service level agreements (SLAs) in the integrated networks of next generation. For this purpose, bandwidth is allocated dynamically and effectively, moreover the path selection algorithm is required while considering the network performance. The proposed algorithm predicts the level of how much the amount of current demand interferes the future potential traffic, and then minimizes it. The proposed algorithm considers the bandwidth on demand, link state, and the information about ingress-egress pairs to maximize the network performance and to prevent the waste of the limited resources. In addition, the interference-prediction supports the bandwidth guarantee in dynamic network to accept more requests. In the result, the proposed algorithm performs the effective admission control and QoS routing. In this paper, we analyze the required conditions of routing algorithms, the aspect of recent research, and the representative algorithms to propose the optimized path selection algorithm adequate to Internet franc engineering. Based on these results, we analyze the problems of existing algorithms and propose our algorithm. The simulation shows improved performance by comparing with other algorithms and analyzing them.