• Title/Summary/Keyword: boundary

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MOLECULAR DYNAMICS SIMULATION OF STRESS INDUCED GRAIN BOUNDARY MIGRATION DURING NANOINDENTATION EXPERIMENTS (나노압흔시 응력에 따른 결정립계거동의 분자역학모사)

  • Yoon, Jang-Hyeok;Kim, Seong-Jin;Chang, Ho
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.11a
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    • pp.39-39
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    • 2003
  • Molecular dynamics (MD) simulation was performed to study the stress induced grain boundary migration caused by the interaction of dislocations with a gain boundary. The simulation was carried out in a Ni block (295020 atoms) with a ∑ = 5 (210) grain boundary and an embedded atom potential for Ni was used for the MD calculation. Stress was provided by indenting a diamond indenter and the interaction between Ni surface and diamond indenter was assumed to have a fully repulsive force to emulate a faction free surface. Results showed that the indentation nucleated perfect dislocations and the dislocations produced stacking faults in the form of a parallelepiped tube. The parallelepiped tube consisted of two pairs of parallel dislocations with Shockley partials and was produced successively during the penetration of the indenter. The dislocations propagated along the parallelepiped slip planes and fully merged onto the ∑ = 5 (210) grain boundary without emitting a dislocation on the other grain. The interaction of the dislocations with the grain boundary induced the migration of the grain boundary plane in the direction normal to the boundary plane and the migration continued as long as the dislocations merged onto the grain boundary plane. The detailed mechanism of the conservative motion of atoms at the gram boundary was associated with the geometric feature of the ∑ = 5 (210) grain boundary.

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A Study on the Topological characteristics of the boundary space in the korean Buddhist temples architecture (한국사찰건축의 경계공간에 나타난 위상기하학적 특성에 관한 연구)

  • Bae Kang-Won;Kim Moon-Duck
    • Korean Institute of Interior Design Journal
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    • v.14 no.5 s.52
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    • pp.26-34
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    • 2005
  • The systematic way of the boundary thought in Buddhism, when applied to the principles of building, determines certain forms to certain temples, and organizes their topological boundary concept structure - the continuous experience of the visitor from his/her entry bridge(connecting), through the main temple gate(neighbourhood), pavilion gate(including), stairs(continuance), to the arrival at the pavilion of the god of a mountain(spiral), which reconstitutes the Buddhist boundary symbolism and philosophy. The topological boundary spaces of temples are an architectural manifestation of Buddhism's Mahayana boundary concept aspects, whose object is to play a productive and active role in the enlightenment of people, serving the very basic end of the religion. The disciplined topological boundary spaces of the temple, as a reification of the boundary symbolisms of Buddhist topological cosmology, corresponds to Buddha-Ksetra, the highest state of existence in the universe. Visitors to the temple are invited to participate in the world of abundant Buddhist boundary concept symbols, and through this process, is enabled to elevate oneself to the transcendent topological boundary world and have a simulated experience of liberation.

Articulatory modification of /m/ in the coda and the onset as a function of prosodic boundary strength and focus in Korean

  • Kim, Sahyang;Cho, Taehong
    • Phonetics and Speech Sciences
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    • v.6 no.4
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    • pp.3-15
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    • 2014
  • An articulatory study (using an Electromagnetic Articulography, EMA) was conducted to explore effects of prosodic boundary strength (Intonational Phrase/IP versus Word/Wd), and focus (Focused/accented, Neutral, Unfocused/unaccented) on the kinematic realization of /m/ in the coda (${\ldots}$am#i${\ldots}$) and the onset (${\ldots}$a#mi${\ldots}$) conditions in Korean. (Here # refers to a prosodic boundary such as an IP or a Wd boundary). Several important points have emerged. First, the boundary effect on /m/s was most robustly observed in the temporal dimension in both the coda (IP-final) and the onset (IP-initial) conditions, generally in line with cross-linguistically observable boundary-related lengthening patterns. Crucially, however, in contrast with boundary-related slowing-down effects that have been observed in English, both the IP-final and IP-initial temporal expansions of Korean /m/s were not accompanied by an articulatory slowing down. They were, if anything, associated with a faster movement in the lip opening (release) phase (into the vowel). This suggests that the mechanisms underlying boundary-related temporal expansions may differ between languages. Second, observed boundary-induced strengthening effects (both spatial and temporal expansions, especially on the IP-initial /m/s) were remarkably similar to prominence (focus)-induced strengthening effects, which is again counter to phrase-initial strengthening patterns observed in English in which boundary effects are dissociated from prominent effects. This suggests that initial syllables in Korean may be a common focus for both boundary and prominence marking. These results, taken together, imply that the boundary-induced strengthening in Korean is different in nature from that in English, each being modulated by the individual language's prosodic system. Third, the coda and the onset /m/s were found to be produced in a subtly but significantly different way even in a Wd boundary condition, a potentially neutralizing (resyllabification) context. This suggests that although the coda may be phonologically 'resyllabified' into the following syllable in a phrase-medial position, its underlying syllable affiliation is kinematically distinguished from the onset.

Despeckling and Classification of High Resolution SAR Imagery (고해상도 SAR 영상 Speckle 제거 및 분류)

  • Lee, Sang-Hoon
    • Korean Journal of Remote Sensing
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    • v.25 no.5
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    • pp.455-464
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    • 2009
  • Lee(2009) proposed the boundary-adaptive despeckling method using a Bayesian model which is based on the lognormal distribution for image intensity and a Markov random field(MRF) for image texture. This method employs the Point-Jacobian iteration to obtain a maximum a posteriori(MAP) estimate of despeckled imagery. The boundary-adaptive algorithm is designed to use less information from more distant neighbors as the pixel is closer to boundary. It can reduce the possibility to involve the pixel values of adjacent region with different characteristics. The boundary-adaptive scheme was comprehensively evaluated using simulation data and the effectiveness of boundary adaption was proved in Lee(2009). This study, as an extension of Lee(2009), has suggested a modified iteration algorithm of MAP estimation to enhance computational efficiency and to combine classification. The experiment of simulation data shows that the boundary-adaption results in yielding clear boundary as well as reducing error in classification. The boundary-adaptive scheme has also been applied to high resolution Terra-SAR data acquired from the west coast of Youngjong-do, and the results imply that it can improve analytical accuracy in SAR application.

Nonlinear boundary parameter identification of bridges based on temperature-induced strains

  • Wang, Zuo-Cai;Zha, Guo-Peng;Ren, Wei-Xin;Hu, Ke;Yang, Hao
    • Structural Engineering and Mechanics
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    • v.68 no.5
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    • pp.563-573
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    • 2018
  • Temperature-induced responses, such as strains and displacements, are related to the boundary conditions. Therefore, it is required to determine the boundary conditions to establish a reliable bridge model for temperature-induced responses analysis. Particularly, bridge bearings usually present nonlinear behavior with an increase in load, and the nonlinear boundary conditions cause significant effect on temperature-induced responses. In this paper, the bridge nonlinear boundary conditions were simulated as bilinear translational or rotational springs, and the boundary parameters of the bilinear springs were identified based on the measured temperature-induced responses. First of all, the temperature-induced responses of a simply support beam with nonlinear translational and rotational springs subjected to various temperature loads were analyzed. The simulated temperature-induced strains and displacements were assumed as measured data. To identify the nonlinear translational and rotational boundary parameters of the bridge, the objective function based on the temperature-induced responses is then created, and the nonlinear boundary parameters were further identified by using the nonlinear least squares optimization algorithm. Then, a beam structure with nonlinear translational and rotational springs was simulated as a numerical example, and the nonlinear boundary parameters were identified based on the proposed method. The numerical results show that the proposed method can effectively identify the parameters of the nonlinear boundary conditions. Finally, the boundary parameters of a real arch bridge were identified based on the measured strain data and the proposed method. Since the bearings of the real bridge do not perform nonlinear behavior, only the linear boundary parameters of the bridge model were identified. Based on the bridge model and the identified boundary conditions, the temperature-induced strains were recalculated to compare with the measured strain data. The recalculated temperature-induced strains are in a good agreement with the real measured data.

Improved Simple Boundary Following Algorithm (개선된 간단한 경계선 추적자 알고리즘)

  • Cheong, Cheol-Ho;Han, Tack-Don
    • Journal of KIISE:Software and Applications
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    • v.33 no.4
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    • pp.427-439
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    • 2006
  • The SBF (Simple Boundary Follower) is a boundary-following algorithm, and is used mainly for image recognition and presentation. The SBF is very popular because of its simplicity and efficiency in tracing the boundary of an object from an acquired binary image; however, it does have two drawbacks. First, the SBF cannot consistently process inner or inner-outer corners according to the follower's position and direction. Second, the SBF requires movement operations for the non-boundary pixels that are connected to boundary pixels. The MSBF (Modified Simple Boundary Follower) has a diagonal detour step for preventing inner-outer corner inconsistency, but is still inconsistent with inner-corners and still requires extra movement operations on non-boundary pixels. In this paper, we propose the ISBF (Improved Simple Boundary Follower), which solves the inconsistencies and reduces the extra operations. In addition, we have classified the tour maps by paths from a current boundary pixel to the next boundary pixel and have analyzed SBF, MSBF, and ISBF. We have determined that the ISBF has no inconsistency issues and reduces the overall number of operations.

Accuracy of Brownian Motion Approximation in Group Sequential Methods

  • Euy Hoon Suh
    • Communications for Statistical Applications and Methods
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    • v.6 no.1
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    • pp.207-220
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    • 1999
  • In this paper, some of the issue about a group sequential method are considered in the Bayesian context. The continuous time optimal stopping boundary can be used to approximate the optimal stopping boundary for group sequential designs. The exact stopping boundary for group sequential design is obtained by using the backward induction method and is compared with the continuous optimal stopping boundary and the corrected continuous stopping boundary.

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