• 제목/요약/키워드: Structural/Relation-based Approach

검색결과 56건 처리시간 0.025초

A Self-Consistent Semi-Analytical Model for AlGaAs/InGaAs PMHEMTs

  • Abdel Aziz, M.;El-Banna, M.;El-Sayed, M.
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제2권1호
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    • pp.59-69
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    • 2002
  • A semi-analytical model based on exact numerical analysis of the 2DEG channel in pseudo-morphic HEMT (PMHEMT) is presented. The exactness of the model stems from solving both Schrodinger's wave equation and Poisson's equation simultaneously and self-consistently. The analytical modeling of the device terminal characteristics in relation to the charge control model has allowed a best fit with the geometrical and structural parameters of the device. The numerically obtained data for the charge control of the channel are best fitted to analytical expressions which render the problem analytical. The obtained good agreement between experimental and modeled current/voltage characteristics and small signal parameters has confirmed the validity of the model over a wide range of biasing voltages. The model has been used to compare both the performance and characteristics of a PMHEMT with a competetive HEMT. The comparison between the two devices has been made in terms of 2DEG density, transfer characteristics, transconductance, gate capacitance and unity current gain cut-off frequency. The results show that PMHEMT outperforms the conventional HEMT in all considered parameters.

생태시민성 개념의 탐색적 논의: 덕성과 기능 및 합의기제를 중심으로 (An Exploration into Meanings of Ecological Citizenship: With Focus on the Values, Skills and Agreement Mechanisms)

  • 김소영;남상준
    • 한국환경교육학회지:환경교육
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    • 제25권1호
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    • pp.105-116
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    • 2012
  • The most necessary thing for education now, is an ecological approach to look at and be conscious of the uncertainty of nature and the structural contradiction of society. In brief, we need to make a judgment on what standard and value are required for a forming righteous relation between nature and human being, and include it in the notion of citizenship. Based on this point of view, this study extracted moral virtues, skills and agreement mechanisms of new citizenship from ecologism, environmental justice and the ecological community, and systematized them. From ecologism and environmental justice, virtues that are inner values to lead ecological citizen's act and skills as capabilities required for correcting environmental injustice, were derived. Then, workings of citizens in a community and directions of each society and education were considered from the ecological community as an utopia where ecological citizens ultimately aim for. As the result, the ecological sensitivity, freedom, creativity, a sense of justice, a sense of responsibility, caring were found to be moral virtues that ecological citizens have to have. Next, ecological thinking skills like systemic thinking, quantitative thinking and empathetic thinking, and principles of deliberation and perturbation as mechanisms to improve communication skill and environmental injustice which have been considered importantly as components of democratic citizenship, were selected as skills of ecological citizens.

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Evaluation of ASCE 61-14 NSPs for the estimation of seismic demands in marginal wharves

  • Smith-Pardo, J. Paul.;Reyes, Juan C.;Sandoval, Juan D.;Hassan, Wael M.
    • Structural Engineering and Mechanics
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    • 제69권1호
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    • pp.95-104
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    • 2019
  • The Standard ASCE 61-14 proposes the Substitute Structure Method (SSM) as a Nonlinear Static Procedure (NSP) to estimate nonlinear displacement demands at the center of mass of piers or wharves under seismic actions. To account for bidirectional earthquake excitation according to the Standard, results from independent pushover analyses in each orthogonal direction should be combined using either a 100/30 directional approach or a procedure referred to as the Dynamic Magnification Factor, DMF. The main purpose of this paper is to present an evaluation of these NSPs in relation to four wharf model structures on soil conditions ranging from soft to medium dense clay. Results from nonlinear static analyses were compared against benchmark values of relevant Engineering Design Parameters, EDPs. The latter are defined as the geometric mean demands that are obtained from nonlinear dynamic analyses using a set of 30 two-component ground motion records. It was found that SSM provides close estimates of the benchmark displacement demands at the center of mass of the wharf structures. Furthermore, for the most critical pile connection at a landside corner of the wharf the 100/30 and DMF approaches produced displacement, curvature, and force demands that were reasonably comparable to corresponding benchmark values.

가상 인플루언서에 대한 소비자의 유사성 지각이 정서적 유대감을 통해 구매의도에 미치는 영향 (The Effect of Consumers' Perception of Similarity Toward Virtual Influencer on Purchase Intention Through Emotional Bond)

  • 이지현;김한구
    • 한국정보시스템학회지:정보시스템연구
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    • 제31권2호
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    • pp.89-110
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    • 2022
  • Purpose To verify the factors that encourage consumers' favorable reaction toward virtual influencer, we proposed consumers' perception of subjective and objective similarity. The purpose of this study is to comprehensively investigate the impacts of consumers' perception toward virtual influencer on purchase intention through psychological distance and parasocial relationship. Design/methodology/approach This study was designed to examine the structural relationships among consumers' perceived external similarity, internal similarity, controllability, animacy toward virtual influencer, psychological distance, parasocial relationship and purchase intention. Findings The results are as follows. First, perceived external similarity, internal similarity, perceived controllability, and animacy had a positive impact on psychological distance. Second, psychological distance had a positive impact on parasocial relationship, whereas it had no significant impact on purchase intention. However, we found that the relation between psychological distance and purchase intention was mediated by parasocial relationship. Lastly, parasocial relationship had a positive impact on purchase intention. Based on these results, this study can propose the way to generate revenue to companies that consider advertising campaign using virtual influencer.

A complete integrity assessment of welded connections under high and low cycle fatigue followed by fracture failure

  • Feng, Liuyang;Liu, Tianyao;Qian, Xudong;Chen, Cheng
    • Steel and Composite Structures
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    • 제43권4호
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    • pp.465-481
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    • 2022
  • This paper presents a comprehensive integrity assessment of welded structural components, including uniform high- and low-cycle fatigue assessment of welded plate joints and fatigue-induced fracture assessment of welded plate joints. This study reports a series of fatigue and fracture tests of welded plate joints under three-point bending. To unify the assessment protocol for high- and low-cycle fatigue of welded plate joints, this study develops a numerical damage assessment framework for both high- and low-cycle fatigue. The calibrated damage material parameters are validated through the smooth coupon specimens. The proposed damage-based fatigue assessment approach describes, with reasonable accuracy, the total fatigue life of welded plate joints under high- and low-cycle fatigue actions. Subsequently, the study performs a tearing assessment on the ductile crack extension of the fatigue-induced crack. The tearing assessment diagram derives from the load-deformation curve of a single-edge notched bend, SE(B) specimen and successfully predicts the load-crack extension relation for the reported welded plate joints during the stable tearing process.

A new approach for predicting sulfate ion concentration in concrete

  • Mohammad Ghanooni-Bagha;Mohsen Ali Shayanfar;Sajad Momen
    • Computers and Concrete
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    • 제33권1호
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    • pp.1-11
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    • 2024
  • Aggressive environmental conditions, and especially the acidic effects of sulfate ion penetration, have reduced the lifetime of concrete structures in some areas, especially coastal and marine areas. In this research, at first, samples made of type II and V cement were kept in a solution of magnesium sulfate (MgSO4) for a period of 90 and 180 days, the change of appearance. Field Emission Scanning Electron Microscopy (FE-SEM) and X-Ray Diffraction (XRD), were used to analyze the microstructure and the complex mineral composition of the concrete after exposure to corrosive environments. Then solving the differential equation governing the sulfate ion penetration, which is based on the second Fick law, it has been tried to determine the concentration of sulfate ions inside the concrete. In the following, an attempt has been made to improve the prediction of sulfate ion concentration in concrete by using Crank's penetration equation. At the same time, the coefficient in the Crank's solution have been optimized by using the Particle Swarm Optimization (PSO algorithm). The comparison between the results shows that the values obtained from Crank's relation are closer to the experimental results than the equation obtained from Fick's second law and shows a more accurate prediction.

민간경호경비의 발전에 대한 자본주의의 사회환경적 해석 (Social Environment Research of Capitalism for the Private Security Development)

  • 김창호;공배완
    • 시큐리티연구
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    • 제7호
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    • pp.125-154
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    • 2004
  • Capitalism is based on a material desire of the human being. the social control of capital value and the management of capital ability reflects the actual condition of the capitalism well. The unconstrained growing and the expansion of capitalism, it finally lost social meaning and an importance of human being element and the safety of the civilian life, began to threat the security of citizen by forming over the material center structure of society. Improving human life quality and material richness on their life leads positive factor of capitalism whereas is causing several crimes through the society which is being threatened around a human being life for a negative factor of the capitalism. Therefore capitalistic social system has offered both a positive factor 'growing' and 'richness' and that of a negative 'structural poverty' and 'lack of security' and they have been remaining the assignment of capitalism 'poverty' and 'security' by settlement in the society for a extremely phenomenon of both sides. The objective of this research is to build its study theory and establish its causal relation by illuminating for the social environment of capitalism for a private guard or a development background of the civil security contributing for citizen security, as well as gets the clue of the development possibility of the civil guard and escort field and the development of capitalism. In Korea because their recognition of the study approach and the social safety for social security control function is still staying first step and our daily life is annoying from various threat of the society, many studies and the realistic necessity of experience related with social security is being studied. In addition, The development possibility of the civil guard and defense at the civil field which will be keep the social security has a wide position but its study approach and realistic comprehension is still in insufficient condition. Consequently, this research is started to grasp the security of civil fiend and to grope a development possibility through the research of capitalism.

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구조방정식을 이용한 TQM 프랙티스와 R&D 성과에 관한 연구: 상황이론적 접근 (The Relationship between TQM Practices and R&D Performance: A Contingency Approach)

  • 홍순욱
    • 기술혁신학회지
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    • 제9권2호
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    • pp.199-235
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    • 2006
  • 본 연구는 구조방정식을 이용하여 TQM 프랙티스와 R&D 성과의 관계를 연구한 것이다. TQM 프랙티스의 수준을 측정하기 위하여 말콤 볼드리지 국가 품질상의 기준을 기본으로 한 측정 도구를 사용하였으며, R&D 성과는 개량지향적 성과와 혁신지향적 성과로 구분하여 측정하였다. 또한, 본 연구모형에 서는 TQM 프랙티스와 R&D 성과의 관계가 상황변수에 따라서 달라질 수 있다고 보고 업무의 불확실성, 시장 변동성, 경쟁의 정도를 상황변수로 채택하고 이들을 고려한 TQM 프랙티스와 R&D 성과에 관한 가설을 설정하였다. 우리나라의 133개 제조업체로부터 우편 설문조사로 얻은 자료를 사용하여 가설 검정을 수행한 결과, TQM 프랙티스는 R&D 성과에 유의한 영향을 미치며, 그 영향의 패턴은 상황 변수에 따라서 다르게 나타나는 것으로 밝혀졌다. 본 연구의 결과는 제조업체 기반의 R&D 환경에서 TQM 프랙티스가 어떠한 역할을 할 수 있는지 보여주기 때문에 R&D 관리에 많은 시사점을 던져준다.

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An extended finite element method for modeling elastoplastic FGM plate-shell type structures

  • Jrad, Hanen;Mars, Jamel;Wali, Mondher;Dammak, Fakhreddine
    • Structural Engineering and Mechanics
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    • 제68권3호
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    • pp.299-312
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    • 2018
  • In this paper, an extended finite element method is proposed to analyze both geometric and material non-linear behavior of general Functionally Graded Material (FGM) plate-shell type structures. A user defined subroutine (UMAT) is developed and implemented in Abaqus/Standard to study the elastoplastic behavior of the ceramic particle-reinforced metal-matrix FGM plates-shells. The standard quadrilateral 4-nodes shell element with three rotational and three translational degrees of freedom per node, S4, is extended in the present study, to deal with elasto-plastic analysis of geometrically non-linear FGM plate-shell structures. The elastoplastic material properties are assumed to vary smoothly through the thickness of the plate-shell type structures. The nonlinear approach is based on Mori-Tanaka model to underline micromechanics and locally determine the effective FGM properties and self-consistent method of Suquet for the homogenization of the stress-field. The elasto-plastic behavior of the ceramic/metal FGM is assumed to follow Ludwik hardening law. An incremental formulation of the elasto-plastic constitutive relation is developed to predict the tangent operator. In order to to highlight the effectiveness and the accuracy of the present finite element procedure, numerical examples of geometrically non-linear elastoplastic functionally graded plates and shells are presented. The effects of the geometrical parameters and the volume fraction index on nonlinear responses are performed.

인문지리학 방법론의 새로운 지평 (New horizon of geographical method)

  • 최병두
    • 대한지리학회지
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    • 제38권
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    • pp.15-36
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    • 1988
  • In this paper, I consider the development of methods in contemporary human geography in terms of a dialectical relation of action and structure, and try to draw a new horizon of method toward which geographical research and spatial theory would develop. The positivist geography which was dominent during 1960s has been faced both with serious internal reflections and strong external criticisms in the 1970s. The internal reflections that pointed out its ignorance of spatial behavior of decision-makers and its simplication of complex spatial relations have developed behavioural geography and systems-theoretical approach. Yet this kinds of alternatives have still standed on the positivist, geography, even though they have seemed to be more real and complicate than the previous one, The external criticisms that have argued against the positivist method as phenomenalism and instrumentalism suggest some alternatives: humanistic geography which emphasizes intention and action of human subject and meaning-understanding, and structuralist geography which stresses on social structure as a totality which would produce spatial phenomena, and a theoretical formulation. Human geography today can be characterized by a strain and conflict between these methods, and hence rezuires a synthetic integration between them. Philosophy and social theory in general are in the same in which theories of action and structural analysis have been complementary or conflict with each other. Human geography has fallen into a further problematic with the introduction of a method based on so-called political ecnomy. This method has been suggested not merely as analternative to the positivist geography, but also as a theoretical foundation for critical analysis of space. The political economy of space with has analyzed the capitalist space and tried to theorize its transformation may be seen either as following humanistic(or Hegelian) Marxism, such as represented in Lefebvre's work, or as following structuralist Marxism, such as developed in Castelles's or Harvey's work. The spatial theory following humanistic Marxism has argued for a dialectic relation between 'the spatial' and 'the social', and given more attention to practicing human agents than to explaining social structures. on the contray, that based on structuralist Marxism has argued for social structures producing spatial phenomena, and focused on theorising the totality of structures, Even though these two perspectives tend more recently to be convergent in a way that structuralist-Marxist. geographers relate the domain of economic and political structures with that of action in their studies of urban culture and experience under capitalism, the political ecnomy of space needs an integrated method with which one can overcome difficulties of orthhodox Marxism. Some novel works in philosophy and social theory have been developed since the end of 1970s which have oriented towards an integrated method relating a series of concepts of action and structure, and reconstructing historical materialism. They include Giddens's theory of structuration, foucault's geneological analysis of power-knowledge, and Habermas's theory of communicative action. Ther are, of course, some fundamental differences between these works. Giddens develops a theory which relates explicitly the domain of action and that of structure in terms of what he calls the 'duality of structure', and wants to bring time-space relations into the core of social theory. Foucault writes a history in which strategically intentional but nonsubjective power relations have emerged and operated by virtue of multiple forms of constrainst wihthin specific spaces, while refusing to elaborate any theory which would underlie a political rationalization. Habermas analyzes how the Western rationalization of ecnomic and political systems has colonized the lifeworld in which we communicate each other, and wants to formulate a new normative foundation for critical theory of society which highlights communicatie reason (without any consideration of spatial concepts). On the basis of the above consideration, this paper draws a new norizon of method in human geography and spatial theory, some essential ideas of which can be summarized as follows: (1) the concept of space especially in terms of its relation to sociery. Space is not an ontological entity whch is independent of society and has its own laws of constitution and transformation, but it can be produced and reproduced only by virtue of its relation to society. Yet space is not merlely a material product of society, but also a place and medium in and through which socety can be maintained or transformed.(2) the constitution of space in terms of the relation between action and structure. Spatial actors who are always knowledgeable under conditions of socio-spatial structure produce and reproduce their context of action, that is, structure; and spatial structures as results of human action enable as well as constrain it. Spatial actions can be distinguished between instrumental-strategicaction oriented to success and communicative action oriented to understanding, which (re)produce respectively two different spheres of spatial structure in different ways: the material structure of economic and political systems-space in an unknowledged and unitended way, and the symbolic structure of social and cultural life-space in an acknowledged and intended way. (3) the capitalist space in terms of its rationalization. The ideal development of space would balance the rationalizations of system space and life-space in a way that system space providers material conditions for the maintainance of the life-space, and the life-space for its further development. But the development of capitalist space in reality is paradoxical and hence crisis-ridden. The economic and poltical system-space, propelled with the steering media like money, and power, has outstriped the significance of communicative action, and colonized the life-space. That is, we no longer live in a space mediated communicative action, but one created for and by money and power. But no matter how seriously our everyday life-space has been monetalrized and bureaucratised, here lies nevertheless the practical potential which would rehabilitate the meaning of space, the meaning of our life on the Earth.

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