• 제목/요약/키워드: critical means

검색결과 972건 처리시간 0.026초

Face stability analysis of rock tunnels under water table using Hoek-Brown failure criterion

  • Li, T.Z.;Yang, X.L.
    • Geomechanics and Engineering
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    • 제18권3호
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    • pp.235-245
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    • 2019
  • This paper presents a novel methodology for face stability assessment of rock tunnels under water table by combining the kinematical approach of limit analysis and numerical simulation. The tunnels considered in this paper are excavated in fractured rock masses characterized by the Hoek-Brown failure criterion. In terms of natural rock deposition, a more convincing case of depth-dependent mi, GSI, D and ${\sigma}_c$ is taken into account by proposing the horizontally layered discretization technique, which enables us to generate the failure surface of tunnel face point by point. The vertical distance between any two adjacent points is fixed, which is beneficial to deal with stability problems involving depth-dependent rock parameters. The pore water pressure is numerically computed by means of 3D steady-state flow analyses. Accordingly, the pore water pressure for each discretized point on the failure surface is obtained by interpolation. The parametric analysis is performed to show the influence of depth-dependent parameters of $m_i$, GSI, D, ${\sigma}_c$ and the variation of water table elevation on tunnel face stability. Finally, several design charts for an undisturbed tunnel are presented for quick calculations of critical support pressures against face failure.

Seismic fragility evaluation of the base-isolated nuclear power plant piping system using the failure criterion based on stress-strain

  • Kim, Sung-Wan;Jeon, Bub-Gyu;Hahm, Dae-Gi;Kim, Min-Kyu
    • Nuclear Engineering and Technology
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    • 제51권2호
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    • pp.561-572
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    • 2019
  • In the design criterion for the nuclear power plant piping system, the limit state of the piping against an earthquake is assumed to be plastic collapse. The failure of a common piping system, however, means the leakage caused by the cracks. Therefore, for the seismic fragility analysis of a nuclear power plant, a method capable of quantitatively expressing the failure of an actual piping system is required. In this study, it was conducted to propose a quantitative failure criterion for piping system, which is required for the seismic fragility analysis of nuclear power plants against critical accidents. The in-plane cyclic loading test was conducted to propose a quantitative failure criterion for steel pipe elbows in the nuclear power plant piping system. Nonlinear analysis was conducted using a finite element model, and the results were compared with the test results to verify the effectiveness of the finite element model. The collapse load point derived from the experiment and analysis results and the damage index based on the stress-strain relationship were defined as failure criteria, and seismic fragility analysis was conducted for the piping system of the BNL (Brookhaven National Laboratory) - NRC (Nuclear Regulatory Commission) benchmark model.

Critical Factors for Acceptance of Social Commerce: A Case Study in Oman

  • FAROOQUE, Murtaza;ALMARHOON, Shahrazad;ALHARIZI, Shamma;MOHAMMED, Aref
    • The Journal of Asian Finance, Economics and Business
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    • 제8권5호
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    • pp.657-665
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    • 2021
  • The study aims to assess the acceptance of social commerce and participate in social commerce amongst Omani people. The questions of the survey Instrument were prepared in English later converted into Arabic. The survey instrument was having two parts; the first part sought the demographic information like age, gender, education, occupation etc. The second part of the instrument was related to the variables, which was in 5-point Likert scale, where 5 means strongly agree while 1 meaning strongly disagree. The data was collected using online and offline surveys, making the number of the valid responses to 478. A conceptual model was developed using the following variables. The selected variables such as "Familiarity" (F), "Trust" (T), "Perceived usefulness" (PU), "Perceived ease of use" (PEU), "Intention to Purchase" (IP). The hypothesis was tested using structural equation modelling. The results indicate that all six hypotheses were supported. The F, T and PEU, and PU was found to be positive and significant related to intention to purchase (p-value 0.003, 0.001, 0.000. & 0.007). Amongst the four, p value of F was found to be the lowest and PU was found to be the highest. This indicate F was strong indicator of IP as compared to others. PUE relates to PU, and F was related to IP.

서식지 적합지수를 이용한 근소만 갯벌 바지락(Ruditapes philippinarum)의 어장적지평가 (Site Assessment Using Habitat Suitability Index for Manila Clam Ruditapes philippinarum in Geunso Bay Tidal Flats)

  • 최용현;홍석진;전승렬;조윤식
    • 한국수산과학회지
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    • 제52권5호
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    • pp.511-518
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    • 2019
  • Evaluating the habitat suitability of potential aquaculture sites for cultured species is critical to the sustainable use of tidal flats. This study evaluated the habitat suitability index (HSI) of 12 sites in a tidal flat aquaculture farm at Geunso Bay, Taean, in June 2016. The parameters used to model the suitability index were Growth (water temperature, chlorophyll ${\alpha}$, hydrodynamics), Survival (sediment-sand, mean size, air exposure), and Environment (DO, salinity). The HSI was calculated using weighted and No weighted geometric means. The results showed high habitat suitability at the bay's entrance (HIS; No weighted, 0.60-0.70; weighted, 0.60). Hydrodynamics, air exposure, sediment-sand and mean size are thought to have a significant impact on habitat selection by Manila clams Ruditapes philippinarum. This study explored the optimum habitat for Manila clams by calculating the HSI, providing basic data for tidal flat management.

A Critical Look at the Prague Rules: Rules on the Efficient Conduct of Proceedings in International Arbitration

  • Jun, Jung Won
    • 한국중재학회지:중재연구
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    • 제29권3호
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    • pp.53-74
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    • 2019
  • Due to the increasingly popular dissatisfaction regarding the inefficiency of arbitral proceedings, the Rules on the Efficient Conduct of Proceedings in International Arbitration, also known as the Prague Rules, was launched in December 2018, with the purpose of increasing the efficiency of arbitral proceedings by encouraging arbitral tribunals to take a more proactive role in conducting their procedures. In this article, the provisions of the Prague Rules are examined, in light of those of the IBA Rules on the Taking of Evidence in International Arbitration, in order to determine the efficacy of the Prague Rules on enhancing the efficiency in arbitral proceedings. The author concludes that more specific and detailed provisions, with respect to what the Rules means by such a "proactive arbitral tribunal," should have been explicitly included in light of the Rules' repeated emphasis on such. Also, the prospective outlook on the Prague Rules is not entirely clear as the text does not appear to fill in the gaps in other widely utilized arbitration rules or to supplement them in a satisfying way. However, given that only a short amount of time has passed since the launch late last year, only time will reveal how effective the Prague Rules will be in increasing the efficiency of arbitral proceedings, in accordance with its intended effect.

고령자 인지기능 지원을 위한 주택 내 홀로그램 시스템 구성 (Configuring a Residential Hologram System to Complement the Cognitive Function of the Elderly)

  • 이은지;박성준
    • 대한건축학회논문집:계획계
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    • 제34권11호
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    • pp.67-74
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    • 2018
  • With the rapid increase in the elderly population, numerous problems arise related to the decreased cognitive function such as the declines of reaction time and concentration which are both resulting from ageing. Recently, ICT-based smart home and other residential services are being developed as a means of complementing human cognitive functions, but the elderly, who are in most cases digital-illiterate, find it hard to utilize these tools actively and if so it usually takes longer time and endeavor for the elderly to be familiarized with ICT devices. In this context, this study suggests a configuration of the holographic system in houses that complement the cognitive function of the elderly with the consideration of the interaction with the vision which is a critical function in the cognitive process. The method of this study consists of a literature review on topics including the characteristics of the cognitive function among the elderly, holographic technology and residential services; a configuration of residential services for different space types, depending on the aspects of the cognitive function among the elderly; and finally a suggestion of a holographic system configuration and application depending on various scenarios.

Ethical Concerns and Issues in the Publication Process

  • KANG, Eungoo;HWANG, Hee-Joong
    • 연구윤리
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    • 제2권1호
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    • pp.7-12
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    • 2021
  • Purpose: The current study suggests that any errors and other inaccuracies noted in the research process should be appropriately communicated to the editorial offices. This will try to eliminate the mistakes that may undermine the value of the publication. The present research thus focuses on the ethical issues and concerns in the publication. Research design, data and methodology: A content analysis applied for this study is suitable because there exists enormous textual data in the realm of ethical concerns and issues in the publication process. The current study investigated manifest and critical themes regarding ethical concerns and issues for research publication. Results: Researchers should consider ethical principles based on suggestions of this study when carrying out a publication for the work to be acceptable in diverse regions and the journal should be made in account of completeness and ensure that all the relevant factors are considered to promote the research's accuracy. Conclusions: Ethical issues denote considerations and moral elements that should be considered by the authors while making a publication. They include Beneficence, which literacy means, do no harm, respect for confidentiality, and anonymity, which is about respecting the rights and dignity of subjects identified based on personal responsibility.

Jonathan Swift's A Tale of a Tub: Carnivalization and Boundaries of Genre

  • Chung, Ewha
    • 영어영문학
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    • 제55권6호
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    • pp.1087-1101
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    • 2009
  • The ongoing attempt to classify and categorize Jonathan Swift's literary work, A Tale of a Tub, as either satire or parody has not only opened issues concerning authorial intent and a present voice but also surfaced questions as to whether Swift identifies with what he is criticizing, thereby becoming the subject he schemes to destroy in his own literary work. In addressing these critical problems, my paper questions the boundaries of genre and analyzes the Tale, not within the conventional terms of literary genre, but by applying Bakhtin's theory of the carnivalistic impulse to Swift's Tale. Rather than focus on finding the author or identifying a voice within the text, Bakhtin's literary vision of carnivalization allows a means of subverting all rules yet holding the work together to present a shocking experience for the reader. Within the Tale, carnivalistic participation includes the reader who at one point is given the detached position of subjective spectator yet eventually decrowns the reader as both a carnivalistic participant and object of the same ridicule and derision once used to judge others. In conclusion, the Tale is revealed as a mocking commentary on the efforts of human beings/participants/writers to ignore the carnival aspects of existence and attempt to elevate themselves to the privileged role of spectator/reader.

Evaluation of 3D printability of cementitious materials according to thixotropy behavior

  • Lee, Keon-Woo;Choi, Myoung Sung
    • Advances in concrete construction
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    • 제11권2호
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    • pp.141-149
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    • 2021
  • This study is a basic research for evaluating the buildability of cementitious materials for three-dimensional (3D) printing. In the cement paste step, the thixotropy behavior according to the resting time, which represents the time interval between each layer, was analyzed. In addition, the relationship between the thixotropy behavior and 3D concrete printing buildability was derived by proposing a measurement method that simulates the 3D concrete printing buildup process. The analysis of the tendency of the thixotropy behavior according to the resting time revealed that the area of the hysteresis loop (AHyst) showed a tendency to increase and then converge as the resting time increased, which means hysteresis loop approach critical resting time for sufficient buildability. In the thixotropy behavior analysis that simulates the 3D concrete printing buildup process, the buildup ratio, which is the recovery rate of the shear stress, showed a tendency to increase and then converge as the resting time increased, which are similar results like hysteresis loop. It was concluded that AHyst and the buildup ratio can be used as parameters for determining the resting time, and they have close relationships with 3D concrete printing buildability.

Comparative assessment of ASCE 7-16 and KBC 2016 for determination of design wind loads for tall buildings

  • Alinejad, Hamidreza;Jeong, Seung Yong;Kang, Thomas H.K.
    • Wind and Structures
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    • 제31권6호
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    • pp.575-591
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    • 2020
  • Wind load is typically considered as one of the governing design loads acting on a structure. Understanding its nature is essential in evaluation of its action on the structure. Many codes and standards are founded on state of the art knowledge and include step by step procedures to calculate wind loads for various types of structures. One of the most accepted means for calculating wind load is using Gust Load Factor or base bending Moment Gust Load Factor (MGLF), where codes are adjusted based on local data available. Although local data may differ, the general procedure is the same. In this paper, ASCE 7-16 (2017), which is used as the main reference in the U.S., and Korean Building Code (KBC 2016) are compared in evaluation of wind loads. The primary purpose of this paper is to provide insight on each code from a structural engineering perspective. Herein, discussion focuses on where the two codes are compatible and differ. In evaluating the action of wind loads on a building, knowledge of the dynamic properties of the structure is critical. For this study, the design of four figurative high-rise buildings with dual systems was analyzed.