• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3254-3272
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• 2017

With the development of wireless access technologies and the popularity of mobile intelligent terminals, cloud computing is expected to expand to mobile environments. Attribute-based encryption, widely applied in cloud computing, incurs massive computational cost during the encryption and decryption phases. The computational cost grows with the complexity of the access policy. This disadvantage becomes more serious for mobile devices because they have limited resources. To address this problem, we present an efficient verifiable outsourced scheme based on the bilinear group of prime order. The scheme is called the verifiable outsourced computation ciphertext-policy attribute-based encryption scheme (VOC-CP-ABE), and it provides a way to outsource intensive computing tasks during encryption and decryption phases to CSP without revealing the private information and leaves only marginal computation to the user. At the same time, the outsourced computation can be verified by two hash functions. Then, the formal security proofs of its (selective) CPA security and verifiability are provided. Finally, we discuss the performance of the proposed scheme with comparisons to several related works.

• The Korean Journal of Health Service Management
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• v.9 no.3
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• pp.81-93
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• 2015

Objectives : The objective of this study was to examine preceding variables that affect the dual commitment of outsourced employees working at hospitals and to analyze the influence of these variables on job performance. Methods : Data were collected from 461 outsourced employees, working at 7 general hospitals, which had introduced the outsourcing system, using a structured, self-administered questionnaires. Frequency, validity/reliability, correlation and path analyses were done for data analysis. Results : The results of the path analyses showed that both commitment to the hiring company and commitment to the client company (hospital) had statistically significant positive effects on job performance. Additionally, when the 'single measurement' approach was used, dual commitment had a larger positive effect, compared with the 'parallel approach.' Among the preceding variables, 'satisfaction for the job itself' was found to be the most important variable affecting dual commitment and job performance. Conclusions : In conclusion, to enhance the job performance of outsourced employees, it is important for management to examine and improve the various factors related to job satisfaction. Additonally, for outsourced employees to have organizational commitments to the hiring and client companies simultaneously, management should emphasize a sense of unity and share organizational values.

• Information Systems Review
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• v.18 no.4
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• pp.17-42
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• 2016

Information security incidents caused by authorized insiders are increasing in financial firms, and this increase is particularly increased by outsourced contractors. With the increase in outsourcing in financial firms, outsourced contractors having authorized right has become a threat and could violate an organization's information security policy. This study aims to analyze the differences between own employees and outsourced contractors and to determine the factors affecting the violation of information security policy to mitigate information security incidents. This study examines the factors driving employees to violate information security policy in financial firms based on the theory of planned behavior, general deterrence theory, and information security awareness, and the moderating effects of employee type between own employees and outsourced contractors. We used 363 samples that were collected through both online and offline surveys and conducted partial least square-structural equation modeling and multiple group analysis to determine the differences between own employees (246 samples, 68%) and outsourced contractors (117 samples, 32%). We found that the perceived sanction and information security awareness support the information security policy violation attitude and subjective norm, and the perceived sanction does not support the information security policy behavior control. The moderating effects of employee type in the research model were also supported. According to the t-test result between own employees and outsourced contractors, outsourced contractors' behavior control supported information security violation intention but not subject norms. The academic implications of this study is expected to be the basis for future research on outsourced contractors' violation of information security policy and a guide to develop information security awareness programs for outsourced contractors to control these incidents. Financial firms need to develop an information security awareness program for outsourced contractors to increase the knowledge and understanding of information security policy. Moreover, this program is effective for outsourced contractors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3826-3851
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• 2016

With traditional data storage solutions becoming too expensive and cumbersome to support Big Data processing, enterprises are now starting to outsource their data requirements to third parties, such as cloud service providers. However, this outsourced initiative introduces a number of security and privacy concerns. In this paper, homomorphic encryption is suggested as a mechanism to protect the confidentiality and privacy of outsourced data, while at the same time allowing third parties to perform computation on encrypted data. This paper also discusses the challenges of Big Data processing protection and highlights its differences from traditional data protection. Existing works on homomorphic encryption are technically reviewed and compared in terms of their encryption scheme, homomorphism classification, algorithm design, noise management, and security assumption. Finally, this paper discusses the current implementation, challenges, and future direction towards a practical homomorphic encryption scheme for securing outsourced Big Data computation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5616-5630
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• 2019

Fully homomorphic encryption allows a third-party to perform arbitrary computation over encrypted data and is especially suitable for secure outsourced computation. This paper investigates secure outsourced computation of multiple matrix multiplication based on fully homomorphic encryption. Our work significantly improves the latest Mishra et al.'s work. We improve Mishra et al.'s matrix encoding method by introducing a column-order matrix encoding method which requires smaller parameter. This enables us to develop a binary multiplication method for multiple matrix multiplication, which multiplies pairwise two adjacent matrices in the tree structure instead of Mishra et al.'s sequential matrix multiplication from left to right. The binary multiplication method results in a logarithmic-depth circuit, thus is much more efficient than the sequential matrix multiplication method with linear-depth circuit. Experimental results show that for the product of ten 32×32 (64×64) square matrices our method takes only several thousand seconds while Mishra et al.'s method will take about tens of thousands of years which is astonishingly impractical. In addition, we further generalize our result from square matrix to non-square matrix. Experimental results show that the binary multiplication method and the classical dynamic programming method have a similar performance for ten non-square matrices multiplication.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.11
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• pp.483-488
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• 2013

Users can access their data anywhere, at any time by using outsourced storage. But they cannot know how service provider manage the data. Even user cannot know when data damaged. To solve these problems, the outsourced storage auditing schemes has been proposed. Most proposed schemes are based on Homomorphic Verifiable Tags. But it has computational efficiency limitation because data used to exponent. In this paper, we propose a novel approach to outsourced storage auditing scheme using coefficient matrix. In the proposed scheme, data used to auditing by coefficient matrix form. Auditing procedures are proceed as solving the linear simultaneous equation. The auditor can audit easily by solving the equation using solution vector. The auditor can audit the n size data using sqrt(n) size data through out proposed scheme.

• Journal of the Korean Dietetic Association
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• v.28 no.2
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• pp.67-84
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• 2022

This study aimed to explore the status of food service outsourcing behavior of long-term care institutions (LTCIs) through a cross-sectional survey using a questionnaire administered between July 16th and August 7th, 2020. The survey respondents were either dietitians or facility managers, who worked at 731 nursing homes, 477 group homes, and 673 day-care centers. Approximately 25.9% of nursing homes, 11.7% of group homes, and 33.1% of day-care centers used a managed-services company to operate their food service units. The main reason for outsourcing food service by nursing homes was related to the staffing of dietitians and cooks, whereas group homes and day-care centers outsourced food services due to factors relating to meal costs and the cooking process. Almost all the LTCIs entered into private contracts for outsourced food services. Only a few food service contracts included the types of meals, nutrition standards such as protein and calories per meal, and the parameter or ratio of food cost. Of the respondents, 84.5% from nursing homes, 87.5% from group homes, and 87.1% from day-care centers agreed that the quality of outsourced food services of the LTCIs should be regulated. Meals are essential for maintaining the health and functional status of LTCI users. As more LTCIs outsource their food services, we suggest the following: (1) Increasing the minimum dietitian staffing standards for LTCIs as per the Welfare of Senior Citizens Act and requiring at least one dietitian for every nursing home, (2) Making it mandatory to use a standard food service contract template when drafting food service contract, and (3) Developing realistic standards for food service operations considering the size and operation type of the LTCIs.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.3
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• pp.113-121
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• 2014

This paper considers a scheduling problem in a two-machine flowshop with outsourcing strategy incorporated. The jobs can be either processed in the first machine or outsourced to outside subcontractors. This paper wants to determine which jobs to be processed in-house and which jobs to be outsourced. If any job is decided to be outsourced, then an additional outsourcing cost is charged The objective of this paper is to minimize the sum of scheduling cost and outsourcing cost under a budget constraint. At first this paper characterizes some solution properties, and then it derives solution procedure including DP (Dynamic Programming) and B&B (Branch-and-Bound) algorithms and a greedy-type heuristic. Finally the performance of the algorithms are evaluated with some numerical tests.

• Korean Management Science Review
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• v.33 no.2
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• pp.1-10
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• 2016

We treats a job scheduling in a 2-machine flow-shop problem with outsourcing strategy allowed. Jobs in the first machine are processed in-house or outsourced to the other companies. In this paper, all the considered jobs are determined to be in-house processed or outsourced. When a job is outsourced, then the firm should pay an outsourcing cost additionally. We want to minimize the sum of the outsourcing costs and the total completion times of finished jobs. In this paper, some solution properties are characterized, and then some heuristic algorithms and a branch-and-bound solution algorithm are derived. This paper evaluates finally the performance of the proposed algorithms during the numerical tests.

• Journal of Information Technology Services
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• v.14 no.4
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• pp.31-44
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• 2015

Local governments in Korea are involved in three types of online shopping sites : 'direct operation', 'outsourced operation', and 'sales agency.' They are different in terms of the site operator and the charging mechanism among a local government, the site operator, and local producers. This study analyzes their differences in site traffic, local producers' participation, promotion, and partnership. The results from the investigation of 72 shopping sites are the following. First, shopping sites of the 'direct operation' type and the 'outsourced operation' type show significantly higher participation of local producers. Second, the 'marketing agency' type has significantly higher number of promotional activities than the 'oursourced type' which has significantly higher number than the 'direct operation' type. Third, the number of partnerships in the 'marketing agency' type is the highest. The 'direct operation' type is the second and significantly higher than the 'outsourced type.' On the basis of the analysis results, this paper suggests an incubation ecosystem model as a better way of involvement by local governments in online shopping sites.