• Coupled systems mechanics
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• v.12 no.2
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• pp.183-197
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• 2023

Scarce research has been published on crack propagation fracture of flywheels manufactured with carbon fiber-reinforced polymers. The present work deals with a calculation method to determine the conditions for which a crack propagates in the axial direction of the flywheel. The assumptions are: flywheels made with just a single thick ply or ply clustering laminates, oriented following the hoop direction; a single crack is analyzed in the plane defined by the hoop and axial directions; the crack starts close to one of the free edges; its axial length is initially large enough so that its tip is far away from that free edge, and the crack expands the entire circumferential perimeter and keeps its concentric position. The developed method provides information for a good design of flywheels. It is concluded that a fracture-based crack propagation criterion generally occurs at a lower speed than a stress-based criterion. Also, that the evolution of failure with thickness using the fracture criterion is exponential, demonstrating that thin flywheels are relatively not sensitive to crack propagation, whereas thick ones are very prone.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.846-854
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• 2024

FEMAXI-ATF is being developed for fuel performance modeling of SiC cladded UO2 fuel with focuses on modeling pellet-cladding mechanical interactions (PCMI). The code considers probability distributions of mechanical strengths of monolithic SiC (mSiC) and SiC fiber reinforced SiC matrix composite (SiC/SiC), while it models pseudo-ductility of SiC/SiC and propagation of cladding failures across the wall thickness direction in deterministic manner without explicitly modeling cracks based on finite element method in one-dimensional geometry. Some hypothetical BWR power ramp conditions were used to test sensitivities of different model parameters on the analyzed PCMI behavior. The results showed that propagation of the cladding failure could be modeled by appropriately reducing modulus of elasticities of the failed wall element, so that the mechanical load of the failed element could be re-distributed to other intact elements. The probability threshold for determination of the wall element failure did not have large influence on the predicted power at failure when the threshold was varied between 25 % and 75 %. The current study is still limited with respect to mechanistic modeling of SiC failure as it only models the propagation of the cladding wall element failure across the homogeneous continuum wall without considering generations and propagations of cracks.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.287-292
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• 2007

In general, the response of bulk material is independent of its size when it comes to considering classical elasticity theory. Because the surface to bulk ratio of the large solids is very small, the influence of surface can be negligible. But the surface effect plays important role as the surface to bulk ratio becomes larger, that is, the contribution of the surface effect must be considered in nano-size elements such as thin film or beam structure. Molecular dynamics computation has been a conventional way to analyze these ultra-thin structures but this method is limited to simulate on the order of $10^6{\sim}10^9$ atoms for a few nanoseconds, and besides, very time consuming. Analysis of structures in submicro to micro range(thin-film, wire etc.) is difficult with classical molecular dynamics due to the restriction of computing resources and time. Therefore, in this paper, the continuum-based method is considered to simulate the overall physical and mechanical properties of the structures in nano-scale, especially, for the thin-film.

• Journal of The Korean Association For Science Education
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• v.33 no.4
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• pp.840-862
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• 2013

This study undertook a methodological investigation on previous research that had proposed alternative methods for analyzing argumentative discourse in science classes in terms of collaborative construction and epistemic enactments of argumentation. The study also proposed a new way of analyzing argumentation discourse based on the achievements and limitations of previous research. The new method was applied to actual argumentation discourse episodes to examine its feasibility. For these purposes, we chose the studies employing Toulmin's argument layout, seeking for a method to analyze comprehensively the structure, content, and justification of arguments, or emphasizing evidence-based reasoning processes of argumentation discourse. In addition, we contrived an alternative method of analyzing argumentative discourse, Discourse Register on the Evidence-Explanation Continuum (DREEC), and applied DREEC to an argumentative discourse episode that occurred in an actual science classroom. The advanced methods of analyzing argumentative discourse used in previous research usually examined argument structure by the presence and absence of the elements of Toulmin's argument layout or its extension. Those methods, however, had some problems in describing and comparing the quality of argumentation based on the justification and epistemic enactments of the arguments, while they could analyze and compare argumentative discourse quantitatively. Also, those methods had limitations on showing participants' collaborative construction during the argumentative discourse. In contrast, DREEC could describe collaborative construction through the relationships between THEMEs and RHEMEs and the links of data, evidence, pattern, and explanation in the discourse, as well as the justification of arguments based on the flow of epistemic enactments of the argumentative discourse.

• Sim-seong Yeon-gu
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• v.38 no.1
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• pp.45-111
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• 2023

This paper examines the apparition of the Virgin Mary revealed in Rue du Bac, Paris, France, in 1830, from a perspective of analytical psychology. To do so, it amplifies the archetypal motifs manifested in the images of the Virgin Mary of Rue du Bac by introducing the medieval alchemical picture titled "Glorification of the body portrayed as the coronation of the Virgin Mary" from Reusner's Pandora (1588). This image of the Virgin Mary is full of archetypal motifs that show the process and end result of individuation, which is the main idea of Jungian psychology. These symbols that depict the individuation process, both in Reusner's Pandora and in the Mary of Rue du Bac, are expressions of mythologems, constituent elements of the collective unconscious. Jung noted that these mythologems are the ultimate base and matrix of all religions. Through examining the archetypal motifs, which appear in the Mary of Rue du Bac, the apparition of the Mary turns out to be the revelation of the archetypal image of the Self in a space-time continuum, which is constellated in the collective unconscious. That is, an archetypal figure revealed itself to a witness' ego-consciousness to whom a space-time continuum functions as a cognitive category. The Mary of Rue du Bac represents the union of the opposites of divinity and humanity, which lacks in the symbolism of the Cross in Christianity. In this regard, she is an image of the new savior, who opens the new aeon of the Aquarius. The revealed image of Mary shows that divinity originates from the inner realm of the human psyche, that corporeal human beings are the matrix in which the divine incarnates, and that human being is the subject of psychological redemption. The image of Mary awakens us to the value of divinity in the human psyche in the times when the spiritual values Christianity has retained declines drastically.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.82-87
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• 1987

In this study a method of shape optimization is applied to two dimensional heat transfer system. For this the optimization problem is defined in a functional form including cost, constraints and the system governing equation. Then the material derivative concept in continuum mechanics and the adjoint variable method are employed for the shape design sensitivity analysis. With the sensitivity analysis results, an optimum is sought with the gradient projection optimization algorithm. The two dimensional isoparametric finite elements are used for accurate analysis and sensitivity calculations. The above method is employed to find the boundary shape to achieve a desired temperature distribution along a segment of the boundary subject to the maximum area constraint.

• The Journal of the Korea Contents Association
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• v.7 no.7
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• pp.96-103
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• 2007

Reincarnation, literally means "to be made flesh again". It is a mystical belief that the soul lives again in a new body after death. In this study, both material and spiritual elements are reincarnated in the form of the formative art in our life. This is similar to the notion of transmigration of the souls in Buddism and Taoism. Even a work of low merit can be an artifact when we give a new meaning and value through the reincarnation. Reincarnation opens another dimension in the formative art and it can be a new source of energy Andy Warhol, who is a central figure in the pop art movement, seems to have an idea of reincarnation in the base of his work. In Korea, there are many experimental arts in design and advertising which shows reincarnation. In the modem society, the activity and mind of reincarnation have been enhanced through Internet and digital medium and people consider reincarnation as a universal philosophy in the art. Especially, the reincarnation as a continuum of design has many implementations. Now the object will be freely adopted, and transformed and it will open a new age in the formative art. We should be ready to enjoy the arts.

• Journal of the Korean Geotechnical Society
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• v.32 no.8
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• pp.35-46
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• 2016

In this study, a sensitivity analysis was carried out by using numerical analysis under the consideration that it is difficult to analyze the behavior of real piled raft foundations on different ground conditions through a real scale test. The program used for numerical analysis is FLAC 3D based on the finite difference method. Piles were modelled by using pile element that is one of the structure elements of FLAC 3D and the ground and raft were modelled by using continuum element. With a fixed pile arrangement of $3{\times}3$, the diameter, length, space of piles, and ground conditions were selected as sensitivity parameters and their mutual correlation were investigated. As a result, the bigger and longer pile diameter, length and pile space are, the bigger the bearing capacity of the piled raft becomes. When pile space exceeded a specific value, however, the piled raft foundation behaved like a shallow foundation supported by only a raft. Also it can be confirmed that the better ground conditions are, the more total bearing capacity of the piled raft foundation increases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2121-2133
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• 1997

A finite element code is developed for 3-D self-contact problems, using continuum elements with a SRI(Selective Reduced Integration) scheme to prevent locking phenomenon by the incompressibility of rubber. Contact treatment is carried out in two ways : using the displacement constraints in case of rigid contact ; and imposing the same contact forces on two contact boundaries in case of self-contact. The finite element code developed is applied to the deformation analysis of C.V.joint boots which maintain lubrication conditions and protect the C.V.joint assembly from impact and dust. The boot accompanies large rotation depending on the rotation of the wheel axis and leading to the self-contact phenomena of the boot bellows. Since this contact phenomenon causes wear of the product and has great influence on the endurance life of the product, it is indispensable to carry out stress analysis of the rubber boots. In case of self-contact, various methods for determining contact forces have been suggested with an appropriate contact formulation. Especially, the types of penetration in self-contact are modularized to accelerate conputation with a contact algorithm.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.37-43
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• 2010

In this paper, a reliability-based design optimization is developed for the topology design of linear structures using a performance measure approach. Spatial domain is discretized using three dimensional Reissner-Mindlin plate elements and design variable is taken as the material property of each element. A continuum based adjoint variable method is employed for the efficient computation of sensitivity with respect to the design and random variables. The performance measure approach of RBDO is employed to evaluate the probabilistic constraints. The topology optimizationproblem is formulated to have probabilistic displacement constraints. The uncertainties such as material property and external loads are considered. Numerical examples show that the developed topology optimization method could effectively yield a reliable design, comparing with the other methods such as deterministic, safety factor, and worst case approaches.