• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권6호
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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.

• 보건의료산업학회지
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• 제9권3호
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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.

• 경영정보학연구
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• 제18권4호
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• pp.17-42
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• 2016

금융회사의 정보보안사고는 정당한 접근 권한을 가진 내부자에 의해 발생하는 사례가 증가하고 있으며, 특히 외주직원에 의한 사고가 증가하고 있다. 금융회사의 외주용역 증가에 따라, 내부자 위협관점에서 정당한 권한을 가진 외주직원은 조직의 정보보안정책을 위반할 수 있는 위협적인 존재가 되고 있다. 본 연구의 목적은 내부직원과 외주직원의 차이를 분석하고 정보보안정책의 위반요인을 확인하여 금융회사의 정보보안정책이 바르게 작용할 수 있도록 하기 위함이다. 금융회사 조직원의 정보보안정책에 대한 위반요인에 대해 계획된 행동이론, 일반억제이론 및 정보보안인식을 기초하여 연구모형을 설계하고, 내부직원과 외주직원 간의 차이를 분석하였다. 분석에 사용된 설문은 온라인과 오프라인으로 수집된 363개의 샘플이 사용되었으며, 그룹 간 차이를 분석하기 위해 내부직원 246명(68%)과 외주직원 117명(32%)을 두 그룹으로 나누어 다중 집단 분석을 이용하였다. 차이 분석을 수행한 결과, 외주직원은 내부직원과 달리 정보보안정책에 대한 위반의도가 정보보안정책에 대한 주관적규범에 영향을 받지 않고 정보보안정책에 대한 행동통제에 영향을 받아 억제되는 것으로 나타났다. 이는 외주직원은 자신이 스스로 할 수 있다고 여기는 자기효능감과 같은 요인에 의해 정보보안정책에 대한 위반의도가 통제되는 것을 나타내는 것이며, 외주직원관리에 이를 응용하여 정보보안교육을 내부직원과 달리 정보보안정책에 대한 조직의 기대를 강조하기보다는 스스로 지킬 수 있을 정도로 외주직원이 기술을 가지고 있음을 강조하고 쉽게 지킬 수 있다는 것을 강조하면 더욱 효과적일 것이다. 결론적으로 금융회사의 외주직원에 대한 정보보안교육 프로그램은 정보보안정책에 대한 이해도를 높일 수 있도록 하여야 하며, 외주직원관리에서는 외주직원이 스스로 지킬 수 있도록 쉬운 보안체계를 유지하는 것이 효과적이라 할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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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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• 제13권11호
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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.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권11호
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• pp.483-488
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• 2013

사용자들은 외부 스토리지를 사용함으로써 언제, 어디서나 자신의 데이터에 접근할 수 있다. 하지만 자신의 데이터가 어떻게 관리되고 있는지는 알 수 없다. 심지어 자신의 데이터에 손상이 발생하여도 인지할 수 없다. 이와 같은 불편을 해결하기 위해 외부 스토리지 검증기법들이 제안되었다. 대부분의 기법들이 준동형 검증 태그(homomorphic verifiable tags)를 사용하고 있지만, 이는 데이터를 지수로 하여 계산하기 때문에 효율성에 한계가 있다. 본 논문에서는 외부 스토리지 무결성 검증의 새로운 접근 방법으로써 계수행렬을 이용한 기법을 제안한다. 제안하는 기법은 데이터를 계수행렬의 형태로 변환하여 검증에 사용한다. 검증과정은 선형연립방정식의 해를 구하는 형태로 진행되며, 검증자는 수식에 해벡터를 대입함으로써 쉽게 검증을 수행할 수 있다. 제안하는 기법을 사용하면 검증자는 sqrt(n) 크기의 데이터로 크기가 n인 데이터를 검증할 수 있다.

• 대한영양사협회학술지
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• 제28권2호
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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.

• 산업경영시스템학회지
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• 제37권3호
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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.

• 경영과학
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• 제33권2호
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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.

• 한국IT서비스학회지
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• 제14권4호
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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.