• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.389-396
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• 2017

Peridynamics has been widely used in the dynamic fracture analysis of brittle materials. Recently, various crack patterns(compact region, floret, Hertz-type crack, etc.) of multilayered glass structures in experiments(Bless et al. 2010) were implemented with a bond-based peridynamic simulation(Bobaru et al.. 2012). The actual glass layers are bound with thin elastic interlayer material while the interlayer is missing from the peridynamic model used in the previous numerical study. In this study, the peridynamic interlayer modeling for the multilayered structures is proposed. It requires enormous computational time and memory to explicitly model very thin interlayer materials. Instead of explicit modeling, fictitious peridynamic particles are introduced for modeling interlayer materials. The computational efficiency and accuracy of the proposed peridynamic interlayer model are verified through numerical tests. Furthermore, preventing penetration scheme based on short-range interaction force is employed for the multilayered structure under compression and verified through parametric tests.

• Journal of the Korean Geographical Society
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• v.41 no.4 s.115
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• pp.491-506
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• 2006

In terms of the importance of ocean as a present and future resource and the Korean peninsular location, it is strongly urged to develop renewed recognition and educational programs on ocean, so as to respond properly to the newly emerging political changes surrounding the country. By setting up the purpose of marine education as engendering greater interests in and knowledge of ocean, this research suggests that the frame of marine education can be founded appropriately on four educational sub-categories: humanity education, territory education, economy education, and resources and environment education. At an operational scale, this paper particularly analyzed ocean- related contents in the 7th national curriculum in order to find substantial ways for strengthening marine education. The study simultaneously compared the result of content analysis with the curriculum of marine education in other countries, and founded that explicit ocean-related contents in the 7th curriculum were significantly limited. Yet, the study alternatively points out that it is possible to use a variety of teaching materials and apply them for writing textbooks or developing teaching-teaming curriculum. I provide some of the ways for strengthening marine education by using marine-related themes in the curriculum of geography education. Marine is not simply one of the key elements in the discipline of geography. But, more importantly, I suggest that geography is particularly useful in developing various and familiar themes such as swimming beach, fishing villages, ports, marine-bound industrial district and port cities into teaching materials.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.355-373
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• 2024

The Generalized Hoek-Brown (GHB) criterion is a nonlinear failure criterion specialized for rock engineering applications and has recently seen increased usage. However, the GHB criterion expresses the relationship between minimum and maximum principal stresses at failure, and when GSI≠100, it has disadvantage of being difficult to express as an explicit relationship between the normal and shear stresses acting on the failure plane, i.e., as a Mohr failure envelope. This disadvantage makes it challenging to apply the GHB criterion in numerical analysis techniques such as limit equilibrium analysis, upper-bound limit analysis, and the critical plane approach. Consequently, recent studies have attempted to express the GHB Mohr failure envelope as an approximate analytical formula, and there is still a need for continued interest in related research. This study presents improved formulations for the approximate GHB Mohr failure envelope, offering higher accuracy in predicting shear strength compared to existing formulas. The improved formulation process employs a method to enhance the approximation accuracy of the tangential friction angle and utilizes the tangent line equation of the nonlinear GHB failure envelope to improve the accuracy of shear strength approximation. In the latter part of this paper, the advantages and limitations of the proposed approximate GHB failure envelopes in terms of shear strength prediction accuracy and calculation time are discussed.