• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3339-3352
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• 2016

In ciphertext-policy attribute-based encryption (CP-ABE) scheme, a user's secret key is associated with a set of attributes, and the ciphertext is associated with an access policy. The user can decrypt the ciphertext if and only if the attribute set of his secret key satisfies the access policy specified in the ciphertext. In the present schemes, access policy is sent to the decryptor along with the ciphertext, which means that the privacy of the encryptor is revealed. In order to solve such problem, we propose a CP-ABE scheme with hidden access policy, which is able to preserve the privacy of the encryptor and decryptor. And what's more in the present schemes, the users need to do excessive calculation for decryption to check whether their attributes match the access policy specified in the ciphertext or not, which makes the users do useless computation if the attributes don't match the hidden access policy. In order to solve efficiency issue, our scheme adds a testing phase to avoid the unnecessary operation above before decryption. The computation cost for the testing phase is much less than the decryption computation so that the efficiency in our scheme is improved. Meanwhile, our new scheme is proved to be selectively secure against chosen-plaintext attack under DDH assumption.

• 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.

• 한국IT서비스학회지
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• 제11권1호
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• pp.83-92
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• 2012

The development of science and technology oriented knowledge society accelerates the convergence between scientific theory and industrial technology and increases the complexity problem of social and economic sectors. These cause the difficulty of securing the reliability and objectivity of science and technology policy. These also are barriers of balanced evaluation between rational science and technology policy making, management, and policy coordination. In this regard, Advanced countries in science and technology develops policy support system and promotes the program of evidence-based SciSIP(Science of Science and Innovation policy) together. This paper introduces a new approach developing science service of science and technology policy utilizing business intelligence technology in Korea. Also, it proposes the integration method of policy knowledge base and component-based service supporting S&T policy decision-making process and introduces services case studies.

• 전자공학회논문지
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• 제50권4호
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• pp.52-58
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• 2013

캐시 메모리의 성능에 큰 영향을 미치는 요소 중 하나인 캐시 교체 알고리즘 중에서 가장 최적의 성능을 가지는 알고리즘은 LRU알고리즘이다. LRU알고리즘은 데이터의 temporal locality특성이 강한 프로그램에서 좋은 성능을 보여주지만, 그렇지 않은 프로그램에서는 많은 캐시 미스를 발생시킨다. 본 논문에서는 LRU알고리즘의 이러한 단점을 개선하기 위한 새로운 카운터 기반 교체 알고리즘인 DCR(Dynamic Counter based Replacement) 알고리즘을 제안한다. 본 논문에서는 캐시에 저장된 이후로 교체되기 전까지 다시 사용되지 않는 데이터인 zero reuse line의 발생 추이를 관찰함으로써 프로그램의 temporal locality 특성이 시간에 따라 동적으로 변화함을 보였다. 그리고 이에 착안하여 제안하는 DCR 알고리즘은 주기적으로 zero reuse line의 수를 카운트하여 프로그램의 temporal locality 변화에 대응할 수 있도록 하였다. DCR 알고리즘은 기존의 LRU알고리즘과 비교하여 최대 2.7%, 평균 0.47%의 미스율 감소를 보였다.

• KDI Journal of Economic Policy
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• 제43권4호
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• pp.45-67
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• 2021

We analyze the social welfare effect when a policy-based financial system (PFS) enters a decentralized financial market. Particularly, the PFS in this case supports the interest spread for corporate loans held by firms with heterogeneous bankruptcy decisions under an imperfect information structure. Although support for capital costs through the PFS expands the economy consistently, the optimal level of PFS out of the corporate loan market is estimated to be 8.6% by a simulation model considering social welfare adjusted by the disutility of labor. This result is much lower than the recent level of PFS in the Korean financial sector.

• 보건행정학회지
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• 제28권3호
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• pp.263-271
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• 2018

Health technology assessment (HTA) is defined as multidisciplinary policy analysis to look into the medical, economic, social, and ethical implications of the development, distribution, and use of health technology. Following the recent changes in the social environment, there are increasing needs to improve Korea's healthcare environment by, inter alia, assessing health technologies in an organized, timely manner in accordance with the government's strategies to ensure that citizens' medical expenses are kept at a stable level. Dedicated to HTA and research, the National Evidence-based Healthcare Collaborating Agency (NECA) analyzes and provides grounds on the clinical safety, efficacy, and economic feasibility of health technologies. HTA offers the most suitable grounds for decision making not only by healthcare professionals but also by policy makers and citizens as seen in a case in 2009 where research revealed that glucosamine lacked preventive and treatment effects for osteoarthritis and glucosamine was subsequently excluded from the National Health Insurance's benefit list to stop the insurance scheme from suffering financial losses and citizens from paying unnecessary medical expenses. For the development of HTA in Korea, the NECA will continue exerting itself to accomplish its mission of providing policy support by health technology reassessment, promoting the establishment and use of big data and HTA platforms for public interest, and developing a new value-based HTA system.

• 한국군사과학기술학회지
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• 제24권5호
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• pp.558-568
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• 2021

The existing underwater vehicle controller design is applied by linearizing the nonlinear dynamics model to a specific motion section. Since the linear controller has unstable control performance in a transient state, various studies have been conducted to overcome this problem. Recently, there have been studies to improve the control performance in the transient state by using reinforcement learning. Reinforcement learning can be largely divided into value-based reinforcement learning and policy-based reinforcement learning. In this paper, we propose the roll controller of underwater vehicle based on Deep Deterministic Policy Gradient(DDPG) that learns the control policy and can show stable control performance in various situations and environments. The performance of the proposed DDPG based roll controller was verified through simulation and compared with the existing PID and DQN with Normalized Advantage Functions based roll controllers.

• 대한지역사회작업치료학회지
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• 제1권2호
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• pp.45-59
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• 2011

목적 : 본 연구는 복지국가의 개념과 사회복지영역을 살펴보고, 우리나라 장애인복지정책의 발전을 비교 분석해 보기 위함이다. 연구방법 : 문헌고찰을 통하여 복지국가의 개념과 사회복지의 영역을 기술하였고, 우리나라의 사회복지정책과 장애인정책을 각 정부별로 비교 분석하였으며 마지막으로 노무현 정부의 장애인정책을 분석하였다. 결과 : 경제성장과 더불어 복지정책과 장애인복지정책은 '선택적 복지'에서 '보편적 복지'의 형태로 발전하였다. 사회복지정책의 영역에 있어서도 과거 이승만 정부시절의 '최소한의 보장'에서 노무현 정부의 '참여복지'에 이르기까지 영역의 확대가 이루어지고 있으며 이러한 현상은 장애인 복지정책에서도 나타나는 현상이다. 결론 : 지역사회 작업치료사는 오늘날 '보편적 사회복지'의 큰 틀에서 등록 장애인 뿐 만 아니라 지역사회의 드러나지 않는 장애를 지닌 일반인과 노인을 위한 방문재활서비스와 같은 미 충족 작업치료서비스를 발견하고 제공해야 할 것이다.

• 대한안전경영과학회지
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• 제8권2호
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• pp.139-153
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• 2006

This paper deals with two forms of preventive replacement policy with minimal repair at failure. Those are, 1. the replacement policy I based on the cumulative operating time. 2. the replacement policy II based on the number of failures. The basic assumptions are; (1) the cost of minimal repair at failure is increasing with the number of failures since the last replacement, (2) the equipment fails stochastically with time.

• Asian Journal of Innovation and Policy
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• 제2권1호
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• pp.1-19
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• 2013

As the catch-up innovation system was exposed to a new competition environment in which second-tier catch-up countries reduced the gap with Korea and advanced Korean firms entered into the frontier product market, it is experiencing system delay in terms of organizational and policy change. Therefore, innovation policy needs to be reorganized from a dynamic perspective to analyze the problems in the transition period and enable the system to overcome organizational and institutional delays. This article investigates the characteristics of transition periods in terms of external environment changes and internal socio-economic pressures. Based on the analysis of environment changes and catch-up system characteristics, it suggests the framework for policy intervention, direction, and practical principles for post catch-up innovation policy. In particular, it suggests the network-based developmental state and policy implementation in order to overcome the limitation of centralized developmental state of catch-up periods.