• 제목/요약/키워드: Flexibility number

검색결과 487건 처리시간 0.024초

The nano scale bending and dynamic properties of isolated protein microtubules based on modified strain gradient theory

  • Benmansour, Djazia Leila;Kaci, Abdelhakim;Bousahla, Abdelmoumen Anis;Heireche, Houari;Tounsi, Abdelouahed;Alwabli, Afaf S.;Alhebshi, Alawiah M.;Al-ghmady, Khalid;Mahmoud, S.R.
    • Advances in nano research
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    • 제7권6호
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    • pp.443-457
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    • 2019
  • In this investigation, dynamic and bending behaviors of isolated protein microtubules are analyzed. Microtubules (MTs) can be considered as bio-composite structures that are elements of the cytoskeleton in eukaryotic cells and posses considerable roles in cellular activities. They have higher mechanical characteristics such as superior flexibility and stiffness. In the modeling purpose of microtubules according to a hollow beam element, a novel single variable sinusoidal beam model is proposed with the conjunction of modified strain gradient theory. The advantage of this model is found in its new displacement field involving only one unknown as the Euler-Bernoulli beam theory, which is even less than the Timoshenko beam theory. The equations of motion are constructed by considering Hamilton's principle. The obtained results are validated by comparing them with those given based on higher shear deformation beam theory containing a higher number of variables. A parametric investigation is established to examine the impacts of shear deformation, length scale coefficient, aspect ratio and shear modulus ratio on dynamic and bending behaviors of microtubules. It is remarked that when length scale coefficients are almost identical of the outer diameter of MTs, microstructure-dependent behavior becomes more important.

실물옵션을 활용한 새만금 환경생태용지사업 분석 (Real Options Analysis for the Eco-Environment Area Project in Saemangeum)

  • 김경석
    • 한국건설관리학회논문집
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    • 제22권6호
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    • pp.87-95
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    • 2021
  • 본 연구는 새만금에 조성되는 환경생태용지사업의 실물옵션기법을 사용하여 경제성분석을 하였다. 30년 동안 운영하는 동안 수익에 영향을 주는 주요 요소들을 정의하였다. 수익의 변동성을 시나리오 분석방법으로 계산하여, 경영적 유연성을 적용할 수 있는 옵션 기반 분석방법을 제시하였다. 환경생태공원 경제성분석에 필요한 이용객수, 입장요금, 체험프로그램요금, 유지관리비용 등은 국내 유사한 환경생태공원의 사례를 분석하였다. 운영 중 포기할 수 있는 옵션권리를 가지는 것으로 가정하여 옵션가치를 계산하였다. B/C는 1미만의 값이 나오고, NPV는 음수로 나와 전통적인 경제성분석방법으로는 사업을 진행할 수가 없으나, 실물옵션분석으로 평가하면 사업의 가치가 상승하여 수익성을 확보할 수 있다. NPV(-466억원)과 옵션가치(281억원)의 가격차이 747억원의 가치상승이 발생하였다. 본 연구를 통해서 환경생태용지사업을 계획하려는 공공기관 및 민간사업자의 투자담당자는 본 연구에서 제시된 실물옵션기법을 활용하여 상황에 적절한 옵션을 선택하여 경제성분석을 할 수 있도록 도움을 줄 수 있을 것이다.

A Lightweight and Privacy-Preserving Answer Collection Scheme for Mobile Crowdsourcing

  • Dai, Yingling;Weng, Jian;Yang, Anjia;Yu, Shui;Deng, Robert H.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제15권8호
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    • pp.2827-2848
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    • 2021
  • Mobile Crowdsourcing (MCS) has become an emerging paradigm evolved from crowdsourcing by employing advanced features of mobile devices such as smartphones to perform more complicated, especially spatial tasks. One of the key procedures in MCS is to collect answers from mobile users (workers), which may face several security issues. First, authentication is required to ensure that answers are from authorized workers. In addition, MCS tasks are usually location-dependent, so the collected answers could disclose workers' location privacy, which may discourage workers to participate in the tasks. Finally, the overhead occurred by authentication and privacy protection should be minimized since mobile devices are resource-constrained. Considering all the above concerns, in this paper, we propose a lightweight and privacy-preserving answer collection scheme for MCS. In the proposed scheme, we achieve anonymous authentication based on traceable ring signature, which provides authentication, anonymity, as well as traceability by enabling malicious workers tracing. In order to balance user location privacy and data availability, we propose a new concept named current location privacy, which means the location of the worker cannot be disclosed to anyone until a specified time. Since the leakage of current location will seriously threaten workers' personal safety, causing such as absence or presence disclosure attacks, it is necessary to pay attention to the current location privacy of workers in MCS. We encrypt the collected answers based on timed-release encryption, ensuring the secure transmission and high availability of data, as well as preserving the current location privacy of workers. Finally, we analyze the security and performance of the proposed scheme. The experimental results show that the computation costs of a worker depend on the number of ring signature members, which indicates the flexibility for a worker to choose an appropriate size of the group under considerations of privacy and efficiency.

Post-yielding tension stiffening of reinforced concrete members using an image analysis method with a consideration of steel ratios

  • Lee, Jong-Han;Jung, Chi-Young;Woo, Tae-Ryeon;Cheung, Jin-Hwan
    • Advances in concrete construction
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    • 제7권2호
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    • pp.117-126
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    • 2019
  • When designing reinforced concrete (RC) members, the rebar is assumed to resist all tensile forces, but the resistance of the concrete in the tension area is neglected. However, concrete can also resist tensile forces and increase the tensile stiffness of RC members, which is called the tension stiffening effect (TSE). Therefore, this study assessed the TSE, particularly after yielding of the steel bars and the effects of the steel ratio on the TSE. For this purpose, RC member specimens with steel ratios of 2.87%, 0.99%, and 0.59% were fabricated for uniaxial tensile tests. A vision-based non-contact measurement system was used to measure the behavior of the specimens. The cracks on the specimen at the stabilized cracking stage and the fracture stage were measured with the image analysis method. The results show that the number of cracks increases as the steel ratio increases. The reductions of the limit state and fracture strains were dependent on the ratio of the rebar. As the steel ratio decreased, the strain after yielding of the RC members significantly decreased. Therefore, the overall ductility of the RC member is reduced with decreasing steel ratio. The yielding plateau and ultimate load of the RC members obtained from the proposed equations showed very good agreement with those of the experiments. Finally, the image analysis method was possible to allow flexibility in expand the measurement points and targets to determine the strains and crack widths of the specimens.

우리나라 어선감척사업 현황과 개선방향 (Present Status and Direction of Improvements in Fishing Vessels Buyback Program in Korea)

  • 이원일;허철행
    • 수산경영론집
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    • 제49권4호
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    • pp.69-81
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    • 2018
  • The fishing vessel buyback program, that is, the project of fishing vessel reduction is a complex challenge that needs to take into consideration for both fishing resource protection and industrial restructuring. By the way, the fishing vessel buyback program in Korea is still poorly fruitful and there are few applications for the project in the country. For example, the buyback program of this nation has some problems like uncertainly set goals, conflicts among targets, no flexibility in the program implementation, low participation in the project and lack in follow-up actions. To solve these problems, this study offers the following alternatives. First, it is setting up detailed targets for fishing vessel buyback. Those targets should be what can be actually driven under policy support, such as reduction in illegal fishing, decrease in an exact number of fishing vessels and decline in fishing capacity rather than what seem to be comprehensive such as protection of coastal or offshore fishery and industrial restructuring. Second, it is taking measures for the livelihood of those who would face disadvantages due to fishing vessel reduction. Those measures providing or supporting the re-education and re-employment of fishery workers and building up systems that help the workers transfer fishing to another job. Third, it is adopting the governance system that overcomes lacks in communications between the fishing vessel buyback program and improves the performance effectiveness of that program. Here, governance means that businesses and authorities concerned in the program interact and cooperate with one another in making and implementing policies related to the project of fishing vessel reduction and assessing the results of that project. Fourth, it is taking actions for fishery reorganization after the fishing vessel buyback program. Factors that can be considered as those actions include supporting fishery workers' cost of fishing vessel reduction, decreasing and modernizing fishing fleets and improving the quality of fishing equipment. In conclusion, the fishing vessel buyback program should be prepared with comprehensive actions or measures that can cope well with a variety of problems that may be arisen from it while keeping itself on the track of its original goals.

Cyclic fatigue, bending resistance, and surface roughness of ProTaper Gold and EdgeEvolve files in canals with single- and double-curvature

  • Khalil, Wafaa A.;Natto, Zuhair S.
    • Restorative Dentistry and Endodontics
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    • 제44권2호
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    • pp.19.1-19.9
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    • 2019
  • Objectives: The purpose of this study was to evaluate the cyclic fatigue, bending resistance, and surface roughness of EdgeEvolve (EdgeEndo) and ProTaper Gold (Dentsply Tulsa Dental Specialties) nickel-titanium (NiTi) rotary files. Materials and Methods: The instruments (n = 15/each) were tested for cyclic fatigue in single- ($60^{\circ}$ curvature, 5-mm radius) and double-curved (coronal curvature $60^{\circ}$, 5-mm radius, and apical curvature of $30^{\circ}$ and 2-mm radius) artificial canals. The number of cycles to fracture was calculated. The bending resistance of both files were tested using a universal testing machine where the files were bent until reach $45^{\circ}$. Scanning electron microscopy and x-ray energy-dispersive spectrometric analysis were used for imaging the fractured segments, while the atomic force microscope was used to quantify the surface roughness average (Ra). Results: EdgeEvolve files exhibited higher cyclic fatigue resistance than ProTaper Gold files in single- and double-curved canals (p < 0.05) and both files were more resistant to cyclic fatigue in single-curved canals than double-curved canals (p < 0.05). EdgeEvolve files exhibited significantly more flexibility than did ProTaper Gold files (p < 0.05). Both files had approximately similar Ni and Ti contents (p > 0.05). EdgeEvolve files showed significantly lower Ra values than ProTaper Gold files (p < 0.05). Conclusions: Within the limitation of this study, EdgeEvolve files exhibited significantly higher cyclic fatigue resistance than ProTaper Gold files in both single- and double-curved canals.

SAUDI ARABIAN UNDERGRADUATE STUDENTS' PERCEPTIONS OF E-LEARNING QUALITY DURING COVID19 PANDEMIC

  • Alkinani, Edrees A.
    • International Journal of Computer Science & Network Security
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    • 제21권2호
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    • pp.66-76
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    • 2021
  • The quality of the E-learning education in Saudi Arabia has been a major concern by many academicians, especially, and people in general as this platform has not been a priority for education. Not until recently, the world has been impacted by the Covid-19 pandemic, which makes every education institution shifted to the online platform to continue the education for the students. Thus, many studies on the perceptions on the online learning have been carried out, and though many are focusing on the perceptions by the education institutions' faculty and administration, there is a lack in the amount of study performed to analyse the students' perceptions of online learning during the pandemic time. The current study is conducted by utilising qualitative methods in order to collect information and investigate the students' perception regarding online learning during the pandemic Covid-19, based on their individual experiences. A number of fifteen (15) students were selected as respondents for the study, in which structured interviews were conducted by using a convenient sampling technique for data collection. Through the discussion, all of the positive and negative perceptions of online learning, as well as the factors contributing to those perceptions were identified. The results of the study found that the positive perceptions were contributed based on the flexibility, cost-effectiveness, availability of the electronic research databases, and well-designed online classroom interfaces. For the negative perceptions from using online learning platforms, the respondents informed that they were contributed by the lecturer's delayed feedback, lack of technical support by lecturers, low in self-esteem and self-motivation, feel isolated, one-way of educational methods, and poorly-designed class materials. Through the findings, the school's administration and lecturers would be able to know the struggles experienced by the students, and eventually come out with better solutions to improve their teaching methods.

Recovery-Key Attacks against TMN-family Framework for Mobile Wireless Networks

  • Phuc, Tran Song Dat;Shin, Yong-Hyeon;Lee, Changhoon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제15권6호
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    • pp.2148-2167
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    • 2021
  • The proliferation of the Internet of Things (IoT) technologies and applications, especially the rapid rise in the use of mobile devices, from individuals to organizations, has led to the fundamental role of secure wireless networks in all aspects of services that presented with many opportunities and challenges. To ensure the CIA (confidentiality, integrity and accessibility) security model of the networks security and high efficiency of performance results in various resource-constrained applications and environments of the IoT platform, DDO-(data-driven operation) based constructions have been introduced as a primitive design that meet the demand of high speed encryption systems. Among of them, the TMN-family ciphers which were proposed by Tuan P.M., Do Thi B., etc., in 2016, are entirely suitable approaches for various communication applications of wireless mobile networks (WMNs) and advanced wireless sensor networks (WSNs) with high flexibility, applicability and mobility shown in two different algorithm selections, TMN64 and TMN128. The two ciphers provide strong security against known cryptanalysis, such as linear attacks and differential attacks. In this study, we demonstrate new probability results on the security of the two TMN construction versions - TMN64 and TMN128, by proposing efficient related-key recovery attacks. The high probability characteristics (DCs) are constructed under the related-key differential properties on a full number of function rounds of TMN64 and TMN128, as 10-rounds and 12-rounds, respectively. Hence, the amplified boomerang attacks can be applied to break these two ciphers with appropriate complexity of data and time consumptions. The work is expected to be extended and improved with the latest BCT technique for better cryptanalytic results in further research.

타원곡선 기반 공개키 암호 시스템 구현을 위한 Scalable ECC 프로세서 (A Scalable ECC Processor for Elliptic Curve based Public-Key Cryptosystem)

  • 최준백;신경욱
    • 한국정보통신학회논문지
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    • 제25권8호
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    • pp.1095-1102
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    • 2021
  • 성능과 하드웨어 복잡도 사이에 높은 확장성과 유연성을 갖는 확장 가능형 ECC 구조를 제안한다. 구조적 확장성을 위해 유한체 연산을 32 비트 워드 단위로 병렬 처리하는 처리요소의 1차원 배열을 기반으로 모듈러 연산회로를 구현하였으며, 사용되는 처리요소의 개수를 1~8개 범위에서 결정하여 회로를 합성할 수 있도록 설계되었다. 이를 위해 워드 기반 몽고메리 곱셈과 몽고메리 역원 연산의 확장 가능형 알고리듬을 적용하였다. 180-nm CMOS 공정으로 확장 가능형 ECC 프로세서 (sECCP)를 구현한 결과, NPE=1인 경우에 100 kGE와 8.8 kbit의 RAM으로 구현되었고, NPE=8인 경우에는 203 kGE와 12.8 kbit의 RAM으로 구현되었다. sECCP가 100 MHz 클록으로 동작하는 경우, NPE=1인 경우와 NPE=8인 경우의 P256R 타원곡선 상의 점 스칼라 곱셈을 각각 초당 110회, 610회 연산할 수 있는 것으로 분석되었다.

Differences in Users' Insights and Increase in The Acceptance Level for Using The BYOD Approach in Government, Non-Profit Organizations, and Private Sectors in Saudi Arabia

  • Alghamdi, Ahmed M.;Bahaddad, Adel A.;Almarhabi, Khalid A.
    • International Journal of Computer Science & Network Security
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    • 제22권7호
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    • pp.332-346
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    • 2022
  • Digital transformation represents one of the main obstacles facing several government, private, and non-profit sectors that help stabilize digital transformation in the Arabic region. One of the helpful ways to improve the level of freedom, productivity, and flexibility among employees to accept the BYOD approach is using their own devices to perform their work both in and outside the workplace. This study focuses to present the differences between the main three economic sectors, which represent the most important pillars of the economy in Saudi Arabia within the Kingdom's Vision 2030. BYOD also has great importance to the stakeholders for raising their awareness by expressing the implications, if the concept of BYOD is widely and correctly adopted. The study uses the diffusion of innovation (DOI) framework and quantitative analysis data to determine the main dimensions and important factors that help increase the awareness of the target audience. The number of participants in this study was 830, and the participants are mixing between the government, private, and non-profit sectors. The main findings showed a significant impact of several factors such as the importance of knowledge, ease of use, employee satisfaction, risk awareness, and attention to increase the level of acceptance in three main sectors study for using the BYOD approach widespread and professional use.