• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.49-54
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• 1998

The flow inside an axial turbomachinery with multi-stage can be characterized as unsteady phenomena. In order to predict accurately these complex unsteady flow patterns including rotor-stator interaction effects, enormous computer resources are required. So it is not compatible in preliminary design process. In this study, steady coupled blade row flow with rotor-stator interaction solver is developed using interrow mixing model and used to predict the performance of the axial fan. To verify the computational method, the calculations are compared with experimental results and show satisfactory agreement with them. The interaction effects on the performance of the axial fan have also been studied by comparing the results of steady coupled blade row and steady single blade row flow calculation.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.337-339
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• 2008

As a shock impinges into a vortex of variable strength, complex shock diffraction can occur. Since a vortex has a fixed rotating direction, the shock wave travelling in one direction creates strong asymmetry in the vortex flow field. The process is that first the shock is divided into two parts by the vortex. One part is moving in the adverse direction opposite to the vortex flow which is captured by the vortex center. The other part is moving in the favorable direction, namely, in the direction same as the vortex flow; it is swung around the vortex, accelerating the vortex flow. In this paper we have investigated numerically using ENO scheme how and why the shock-vortex interaction patterns appear so different for different parametric values. Conclusion is that there are three different types of shock-vortex interaction depending on two related parameters: shock Mach number and vortex Mach number. We present a parameter map by which we can discern what type of interaction pattern appears as a shock impinges into a vortex.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.337-339
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• 2008

Abstract: As a shock impinges into a vortex of variable strength, complex shock diffraction can occur. Since a vortex has a fixed rotating direction, the shock wave travelling in one direction creates strong asymmetry in the vortex flow field. The process is that first the shock is divided into two parts by the vortex. One part is moving in the adverse direction opposite to the vortex flow which is captured by the vortex center. The other part is moving in the favorable direction, namely, in the direction same as the vortex flow; it is swung around the vortex, accelerating the vortex flow. In this paper we have investigated numerically using ENO scheme how and why the shock-vortex interaction patterns appear so different for different parametric values. Conclusion is that there are three different types of shock-vortex interaction depending on two related parameters: shock Mach number and vortex Mach number. We present a parameter map by which we can discern what type of interaction pattern appears as a shock impinges into a vortex.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.480-485
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• 2004

If a wall separates the bounded and unbounded spaces, then the wall's role in transporting the acoustic characteristics of the two spaces is not well defined. In this paper, we attempted to see how the acoustic characteristical of two spaces are really affected by the spatial characteristics of the wall. In order to understand coupling mechanism, we choose a finite space and a semi-infinite space separated by the flexible or rigid wall and an opening. A volume interaction can be occurred in structure boundary and a pressure interaction can be happened in the opening boundary. For its simplicity, without loosing generality, we use rather simplified rectangle model instead of generally shaped model. The source impedance is presented to the various types of boundaries. The distributions of pressure and active intensity are also presented at the cavity and structure-dominated modes. The resulting modification, shifts of mode1 frequencies and changing of standing wave patterns to satisfy both coupled boundary conditions and governing equations, are presented.

• Korean Journal of Child Studies
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• v.25 no.1
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• pp.77-92
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• 2004

The present study conducted in the Children's Museum investigated patterns of participation by type of exhibit and interaction with 150 5-to 12-year-old children and 50 mothers. A timing and tracking observation checklist was used to document time spent at each type of exhibit and the interaction of children and mothers. All children chose and spent more time interacting with participatory than non-participatory exhibits and they chose more participatory exhibits than mothers. Mothers chose more non-participatory than participatory exhibits and spent more time with non-participatory exhibits than the preschool group. The preschool age group interacted with mothethan other interactions.

• Journal of Powder Materials
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• v.27 no.4
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• pp.339-342
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• 2020

Since the interaction between the second-phase particle and grain boundary was theoretically explained by Zener and Smith in the late 1940s, the interaction of the second-phase particle and grain boundary on the microstructure is commonly referred to as Zener pinning. It is known as one of the main mechanisms that can retard grain growth during heat treatment of metallic and ceramic polycrystalline systems. Computer simulation techniques have been applied to the study of microstructure changes since the 1980s, and accordingly, the second-phase particle-grain boundary interaction has been simulated by various simulation techniques, and further diverse developments have been made for more realistic and accurate simulations. In this study, we explore the existing development patterns and discuss future possible development directions.

• English Language & Literature Teaching
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• v.16 no.1
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• pp.123-142
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• 2009

The present study used multi-faceted Rasch measurement to explore the characteristics and bias patterns of non-native raters when they scored L2 writing tasks. Three raters scored 254 writing tasks written by Korean university students on two topics adapted from the TOEFL Test of Written English (TWE). The written products were assessed using a five-category rating scale (Content, Organization, Language in Use, Grammar, and Mechanics). The raters only showed a difference in severity with regard to rating categories but not in task types. Overall, the raters scored Grammar most harshly and Organization most leniently. The results also indicated several bias patterns of ratings with regard to the rating categories and task types. In rater-task bias interactions, each rater showed recurring bias patterns in their rating between two writing tasks. Analysis of rater-category bias interaction showed that the three raters revealed biased patterns across all the rating categories though they were relatively consistent in their rating. The study has implications for the importance of rater training and task selection in L2 writing assessment.

• Korean Journal of Child Studies
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• v.28 no.1
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• pp.17-35
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• 2007

This study examined whether sequential transition patterns of social play differed by children's social competence. The social competence of sixty 5-year-old children was rated by their teachers using the Social Competence Scale(NICHD Early Child Research Network, 1996). Children's social play was observed during free play and coded by criteria developed by Robinson et al(2003). Results showed differences in children's social play behaviors by social competence and differences in the transition patterns of children's social play level by social competence. Children with higher social competence showed a transition pattern moving toward cooperative-social interaction, whereas children with lower social competence showed a transition pattern moving backward to solitary or onlooker behavior.

• English Language & Literature Teaching
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• v.18 no.3
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• pp.53-75
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• 2012

The present study examined the role of language proficiency in dyadic discourse in the organization of repairs and the distribution of linguistic features contained in repairs. One native speaker of English and five non-native speakers participated and formed three dyads: one same-proficiency NNS-NNS (non-native speaker), one different-proficiency NNS-NNS, and one NS (native speaker)-NNS dyads. Results showed that overall repair patterns in this type of interaction were more conversational than didactic, and that the degree of difference in proficiency between the participants in the dyad influenced repair patterns and the distribution of linguistic features in relation to repair patterns. Also, discussed in the present paper are some implications of the results and other issues related to language learning.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.394-394
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• 2013

The spin-orbit interaction has received great attention in the field of spintronics, because of its property and applicability. For instance, the spin-orbit interaction induces spin precession which is the key element of spin transistor proposed by Datta and Das, since frequency of precession can be controlled by electric field. The spin-orbit interaction is classified according to its origin, Dresselhaus and Rashba spin-orbit interaction. In particular, the Rashba spin-orbit interaction is induced by inversion asymmetry of quantum well structure and the slope of conduction band represents the strength of Rashba spin-orbit interaction. The strength of spin-orbit interaction is experimentally obtained from the Shubnikov de Hass (SdH) oscillation. The SdH oscillation is resistance change of channel for perpendicular magnetic field as a result of Zeeman spin splitting of Landau level, quantization of cyclotron motion by applied magnetic field. The frequency of oscillation is different for spin up and down due to the Rashba spin-orbit interaction. Consequently, the SdH oscillation shows the beat patterns. In many research studies, the spin-orbit interaction was treated as a tool for electrical manipulation of spin. On the other hands, it can be considered that the Rashba field, effective magnetic field induced by Rashba effect, may interact with external magnetic field. In order to investigate this issue, we utilized InAs quantum well layer, sandwiched by InGaAs/InAlAs as cladding layer. Then, the SdH oscillation was observed with tilted magnetic field in y-z plane. The y-component (longitudinal term) of applied magnetic field will interact with the Rashba field and the z-component (perpendicular term) will induce the Zeeman effect. As a result, the strength of spin-orbit interaction was increased (decreased), when applied magnetic field is parallel (anti-parallel) to the Rashba field. We found a possibility to control the spin precession with magnetic field.