• Journal of the Society of Naval Architects of Korea
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• v.52 no.6
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• pp.478-484
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• 2015

Knowledge about ice load distribution along the ship hull due to ship-ice interaction can provide important background information for the development of design codes for ice-going vessels. The objective of this study is to understand ship and ice interaction phenomena and determine the magnitude of ice load acting along a ship hull. The model tests were performed in the ice model basin in Korea Research Institute of Ships and Ocean engineering (KRISO) with the model of icebreaking ship Araon. Self-propulsion tests in level ice were performed with three difference model ship speeds. In the model tests, three tactile sensors were installed to measure the spatial distribution of ice load acting at different locations on a model ship, such as the bow and shoulder areas. Variation in the distribution of ice load acting on a model hull with ship speed is discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.263-269
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• 2006

The objective of the present work is to develop a time-domain numerical method of broadband noise in a cascade of airfoils. This paper focuses on dipolar broadband noise sources, resulting from the interaction of turbulent inflows with the flat-plate airfoil cascade. The turbulence response of a two-dimensional cascade is studied by solving both of the linearised and the full nonlinear Euler equations employing accurate higher order spatial differencing, time stepping techniques and non-reflecting inflow/outflow boundary condition. The time-domain result using the linearised Euler equations shows good agreement with the analytical solution using the modified LINSUB code. Through the comparison of the nonlinear time-domain result using the full nonlinear Euler equations with the linear, it is found that the acoustic mode amplitude of the nonlinear response is less than that of the linear response due to the energy cascade from low frequency components to the high frequency ones. Considering the merits of the time-domain methods over the typical time-linearised frequency-domain analysis, the current method is expected to be promising tools for analyzing the effects of the airfoil shapes, non-uniform background flow, linear-nonliear regimes on the broadband noise due to turbulence-cascade interaction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.718-725
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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 characteristics 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 modal frequencies and changing of standing wave patterns to satisfy both coupled boundary conditions and governing equations, are presented.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.22-27
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• 2009

Target design study to improve the quality of an accelerated proton beam from the interaction of a high-intensity short pulse laser with an overdense plasma slab has been accomplished by using a two-dimensional, fully electromagnetic and relativistic particle-in-cell (PIC) simulation. The target consists of a thin core part and a thick peripheral part of equivalent plasma densities, while the ratio of the radius of the core part to the laser spot size, and the position of the peripheral part relative to the fixed core part were varied. The positive effects of this core-peripheral target structure could be expected from the knowledge of the typical target normal sheath acceleration (TNSA) mechanism in a laser-plasma interaction, and were apparently evidenced from the comparison with the case of a conventional simple planar target and the case of the transversal size reduction of the simple planar target. Improvements of the beam qualities including the collimation, the forward directionality, and the beam divergence were verified by detailed analysis of relativistic momentum, angular directionality, and the spatial density map of the accelerated protons.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.3
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• pp.117-129
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• 2013

The increasing demand for monitoring wildfires and their impact on the land surface have prompted studies of burned area extraction and analysis. To differentiate burned and unburned area, the earlier method of the Moderate Resolution Imaging Spectro-radiometer (MODIS) Burned Area Detection Algorithm was proposed to estimate the change in land surface based on the reflectance energy. The energy, whose wavelengths are sensitive to burning, was selected to calculate the change parameter $Z_{score}$. This method was applied using the MODIS images to produce a MODIS Burned Area product. The approach was to simplify this algorithm to make it compatible with the Landsat 7 ETM+ SLC-off images. To extract the refined version of burned regions, post-processing was carried out by applying a median filter, dilation morphology algorithm, and finally a gap filling method. The experimental results showed that the detailed burned areas extracted from the proposed method exhibited more spatial details than those of the MODIS Burned products in the large U.S areas. The results also revealed the discontinuous distribution of burned regions in Vietnam forests.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.426-432
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• 2004

Large-Eddy Simulation (LES) is applied for the simulation of compressible flat plate boundary with Reynolds number up to 5 X 10$^{5}$ . Numerical examples include shock/boundary layer interaction and boundary layer transition, aiming future application to the analysis of transonic fan/compressor cascades. The present LES code uses hybrid com-pact/WENO scheme for the spatial discretization and compact diagonalized implicit scheme for the time integration. The present code successfully predicted the bypass transition of subsonic boundary layer. As for supersonic turbulent boundary layer, mean and fluctuation velocity of the attached boundary, as well as the evolution of the friction coefficient and the displacement thickness both upstream and downstream of the separation region are all in good agreement with experiment. The separation point also agreed with the experiment. In the simulation of the shock/laminar boundary layer interaction, the dependence of the transition upon the shock strength is reproduced qualitatively, but the extent of the separation region is overpredicted. These numerical examples show that LES can predict the behavior of boundary layer including transition and shock interaction, which are hardly managed by the conventional Reynolds-averaged Navier-Stokes approach, although there needs to be more effort before achieving quantitative agreement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.812-817
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• 2005

The objective of the present work is to develop a time-domain numerical method of broadband noise in a cascade of airfoils. This paper focuses on dipole broadband noise sources, resulting from the interaction of turbulent inflows with the flat-plate airfoil cascade. The turbulence response of a two-dimensional cascade is studied by solving both of the linearised and full nonlinear Euler equations employing accurate higher order spatial differencing, time stepping techniques and non-reflecting inflow/outflow boundary condition. The time-domain result using the linearised Euler equations shows good agreement with the analytical solution using the modified LINSUB code. Through the comparison of the nonlinear time-domain result using the full nonlinear Euler equations with the linear, it is found that the acoustic mode amplitude of the nonlinear response is less than that of the linear response due to the energy cascade from low frequency components to the high frequency ones. Considering the merits of the time-domain methods over the typical time-linearised frequency-domain analysis, the current method is expected to be promising tools for analyzing the effects of the airfoil shapes, non-uniform background flow, linear-nonliear regimes on the broadband noise due to gust-cascade interaction.

• Journal of Ocean Engineering and Technology
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• v.31 no.2
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• pp.121-129
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• 2017

The present study numerically investigated the influence of the waveform distribution on the tsunami-vegetation interaction using a non-reflected wave generation system for various tsunami waveforms in a two-dimensional numerical wave tank. First, it was possible to determine the wave attenuation mechanism due to the tsunami-vegetation interaction from the spatial waveform, flow field, vorticity field, and wave height distribution. The combination of fluid resistance in the vegetation and a large gap and creates a vortex according to the flow velocity difference in and out of the vegetation zone. Thus, the energy of a tsunami was increasingly reduced, resulting in a gradual reduction in wave height. Compared to existing approximation theories, the double volumetric ratio of the waveform increased the reflection coefficient of the tsunami-vegetation interaction by 34%, while decreasing the transfer coefficient and energy attenuation coefficient by 25% and 13%, respectively. Therefore, the hydraulic characteristics of a tsunami is highly likely to be underestimated if the solitary wave of the approximation theory is applied for the tsunami.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.937-944
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• 2006

Although people's anxiety about the environmental problem has been getting higher, they are not provided good quality of knowledge about the environment. Based on this situation, Ecoblog can be a new type of online community to educate the public in ecological knowledge. Especially, Ecoblog can be utilized as a method of "preventive education", and it will contribute to reduce great amounts of environmental budget to restore contaminated environment to previous condition. Ecoblog also utilizes the concept of blog which user can create and append their site with chosen themes. A weblog or a blog is a non-commercial webpage regularly updated through the use of a blogging software which allows the user to "publish" kinds of amalgamations of text and graphics to the page as posts. The technology offered in Ecoblog is utilizing the concept of 4D place and game metaphor in order to provide users the sense of participation, interaction and immersion among them and the growing community. Thus, it requires applying the CAAD technology by implementing semantically well-defined building data model as a core database to create a 4D virtual community. This research focuses on defining a 4d spatial framework suitable for developing an online ecological community. Through our study, the state-of-the-art of online community has been studied at the first step. Second, the scenario of using EcoBlog described with content, visualization and navigation are defined based on the critical features derived at the first step. Finally, a 4d spatial framework composed of semantic building data model, content and rule database is constructed to propose factors that are necessary to establish an ecological virtual community. In conclusion, our framework could enhance the comprehension and interaction between users and virtual buildings in the ecological community by integrating the concept of game design, 4D CAD and semantic data model. Such framework can be applied to any online community for an educational purpose.

• Toxicological Research
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• v.24 no.1
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• pp.1-9
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• 2008

Ptdlns(4,5)$P_2$ is a key cellular phosphoinositide that localizes in separate and distinctive pools in subcellular membrane and vesicular compartments. In membranes, Ptdlns(4,5)$P_2$ acts as a precursor to second messengers and is itself a main signaling and targeting molecule. Specific subcellular localization of type I PIP kinases directed by interacting with specific targeting module differentiates Ptdlns(4,5)$P_2$ production in a spatial and temporal manner. Several lines of evidences support the idea that Ptdlns(4,5)$P_2$ is generated in very specific pools in a spatial and temporal manner or by feeding Ptdlns(4,5)$P_2$ directly to effectors. In this concept, the interaction of PIPKI isoforms with a specific targeting module to allow precise subcellular targeting modulates highly specific Ptdlns(4,5)$P_2$ synthesis and channeling overall effectors. For instance, localization of PIPKI${\gamma}$661 to focal adhesions by an interaction with talin results in spatial and temporal production of Ptdlns(4,5)$P_2$, which regulates EGF-stimulated directional cell migration. In addition, Type $I{\gamma}$ PIPK is targeted to E-cadherin in cell adherence junction and plays a role in controlling dynamics of cell adherence junction and endocytosis of E-cadherin. Characterizing how PIP kinase isoforms are regulated by interactions with their targeting modules, as well as the mechanisms by which their product, Ptdlns(4,5)$P_2$, exerts its effects on cellular signaling processes, is crucial to understand the harmonized control of numerous cellular signaling pathways. Thus, in this review the roles of the Ptdlns(4)P(5) kinases and Ptdlns(4,5)$P_2$ were described and critically reviewed in terms of regulation of the E-cadherin trafficking, cell migration, and formation of cell adherence junction which is indispensable and is tightly controlled in epithelial-to-mesenchymal transition process.