• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1174-1179
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• 2000

In recent years, the structural shock response to underwater explosion has been studied as much, or more, through numerical simulations than through testing for several reasons. Very high costs and sensitive environmental concerns have kept destructive underwater explosion testing to a minimum. Increase of simulation capabilities and sophisticated simulation tools has made numerical simulations more efficient analysis methods as well as more reliable testing aids. For the simulation of underwater explosions against, surface ships or submerged structures one has to include the effects of the explosive shock wave, the motion of the gaseous reactive products, the local cavitation collapse, the different nonlinear structural properties and the complex fluid-structure interaction phenomena. In this study, as benchmark step for the validation of hydrocode LS/DYNA3D and of technology of fluid-structure interaction problems, two kinds of cavitation problems are analyzed and structural shock response of floating ship model are compared with experimental result.

• Structural Engineering and Mechanics
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• v.65 no.4
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• pp.359-368
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• 2018

Dynamic analysis of complex and large structures may be costly from a numerical point of view. For coupled vibroacoustic finite element models, the importance of reducing the size becomes obvious because the fluid degrees of freedom must be added to the structural ones. In this paper, a component mode synthesis method is proposed for large vibroacoustic interaction problems. This method couples fluid subdomains and dynamical substructuring of Craig and Bampton type. The acoustic formulation is written in terms of the velocity potential, which implies several advantages: coupled algebraic systems remain symmetric, and a potential formulation allows a direct extension of Craig and Bampton's method to acoustics. Those properties make the proposed method easy to implement in an existing finite element code because the local numerical treatment of substructures and fluid subdomains is undifferentiated. Test cases are then presented for axisymmetric geometries. Numerical results tend to prove the validity and the efficiency of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.3
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• pp.107-115
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• 2002

This parer presents the analysis of hot gas flow in puffer-type circuit breakers using FVFLIC method. For the analysis of arc-flow interaction, the flow field is analyzed from the equations of conservation for mass, momentum and energy with the assumption of local thermodynamic equilibrium state. The arc is represented as the energy source term composed of ohmic heating and radiation term in the energy conservation equation. Ohmic heating is computed by the electric field analysis only within the conducting plasma region. An approximate radiation transport model is employed for the evaluation of emission and absorption of the radiation. The analysis method was applied to the real circuit breaker model and simulation results such as pressure rise and arc voltage were compared with the experimental ones.

• Water Engineering Research
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• v.1 no.3
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• pp.187-197
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• 2000

This paper describes an adaptive quadtree-based 2DH wave-current interaction model which is able to predict wave breaking, shoaling, refraction, diffraction, wave-current interaction, set-up and set-down, mixing processes (turbulent diffusion), bottom frictional effects, and movement of the land-water interface at the shoreline. The wave period-and depth-averaged governing equations are discretised explictly by means of an Adams-Bashforth second-order finite difference technaique on adaptive hierarchical staggered quadtree grids. Grid adaptation is achieved through seeding points distributed according to flow criteria(e.g. local current gradients). Results are presented for nearshore circulation at a sinusoidal beach. Enrichment permits refined modelling of important localised flow features.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.84-87
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• 2006

We suggest a procedure entangling two spin-1/2 particles at distant positions such that they cannot be directly entangled via local interaction. An already entangled pair is used to transfer the entanglement to another pair of particles by way of interaction. This scheme of nonlocal generation of entanglement can be used in the construction of a two-qubit universal gate.

• Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.73-78
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• 2015

In this paper, we propose a new approach to providing interactive and collaborative lens among multi-users for supporting level-of-detailed views using smartphones in a public display. In order to provide smartphone-based lens capability, the locations of smartphones are effectively detected and tracked using Kinect, which provides RGB data and depth data (RGB-D). In particular, human skeleton information is extracted from the Kinect 3D depth data to calculate the smartphone location more efficiently and correctly with respect to the public display and to support head tracking for easy target selection and adaptive view generation. The suggested interactive and collaborative lens using smartphones not only can explore local spaces of the shared display but also can provide various kinds of activities such as LOD viewing and collaborative interaction. Implementation results are given to show the advantage and effectiveness of the proposed approach.

• Journal of Ship and Ocean Technology
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• v.9 no.1
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• pp.38-46
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• 2005

Survivability improvement method for naval ship design has been continually developed. In order to design naval ships considering survivability, it is demanded that designers should establish reasonable damage conditions by air explosion. Explosion may induce local damage as well as global collapse to the ship. Therefore possible damage conditions should be realistically estimated in the design stage. In this study the authors used ALE technique, one of the structure-fluid interaction techniques, to simulate air explosion and investigated survival capability of damaged naval ships. Lagrangian-Eulerian coupling algorithm, equation of the state for explosive and air, and simple calculation method for explosive loading were also reviewed. It is shown that air explosion analysis using ALE technique can evaluate structural damage after being attacked. This procedure can be applied to the real structural design quantitatively by calculating surviving time and probability.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.120-125
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• 2003

Recently, lateral jet has been adopted as an effective control device for high maneuverable tactical missiles in supersonic regime. Aerodynamic interference caused by the lateral jet can be categorized into two phenomena : local interaction redistributing surface pressure near the jet exit region and downstream interaction affecting tail control effectiveness. As part of on-going research, this paper deals with the aerodynamic modeling to predict the variation of force and moment when lateral jet of is activated on the missile body. For this purpose, a series of numerical simulation has been performed and the results are presented. Using the information obtained by CFD, aerodynamic model of preliminary level has been constructed and is reviewed. Some relevant comparison with wind tunnel tests are presented.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.542-546
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• 2004

Fully non-local Quasicontinuum method using sub-divided region with Hermite interpolation function is proposed for simulation of carbon nanotube. Tersoff-Brenner potential is adopted for interaction of bonded atoms and also van der Waals force for non-bonded interaction. Bending of single wall carbon nanotube with chirality (20,0) and 15nm length is simulated up to 90 degree. Bending of double wall carbon nanotube with chirality (20,0) and (12,0) is simulated up to 65 degree. Bending of four wall carbon nanotube is simulated up to 45 degree.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.607-613
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• 2007

Current changes in the written language curriculum have lead to emphasis being placed on the process involved in writing rather than the product. Writing is being viewed as a means of exploration, with text being manipulated in revision until a clear message is conveyed. This study focuses on the use of the computer in written language, as a tool to facilitate learning, increase interaction and alter children's attitudes. Some children from a local primary school participated in a project which gave them access to a computer and guidance during the process of revision. Evaluation of this study showed a two-fold effect. Firstly the writing behaviors of the children developed with their increased involvement in the process. For example, the children began to read what they had written thereby independently evaluating the content. Secondly, arising from this, as a sense of control over their writing was gained the children's attitudes towards writing became more positive.