• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.4
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• pp.12-21
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• 2006

Recently, Very large and high resolution geological data from aerial or satellite imagery are available. Many researches and applications require to do realtime visualization of interest geological area or entire planet. Important operation of wide-spreaded terrain realtime visualization technique is the appropriate model resolution selection from pre-processed multi-resolution model hierarchy depend upon participant's view. For embodying such realtime rendering system with large geometric data, Preprocessing multi-resolution hierarchy from large scale geological information of interest area is required. In this research, recent Cubic multiresolution 4-8 tile hierarchy is selected for global planetary applications. Based upon the tile hierarchy, It constructs the selective terminal level tile mesh for original geological information area and starts to sample individual generated tiles for terminal level tiles. It completes the hierarchy by constructing intermediate tiles with low pass filtering in bottom-up direction. This research embodies series of efficient cubic 4-8 tile hierarchy construction mechanism with out-of-core storage. The planetary scale Mars' geographical altitude data and image data were selected for the experiment.

• Journal of Digital Contents Society
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• v.9 no.4
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• pp.771-778
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• 2008

A Device performance analyzing method for appropriate level in hybrid rendering model is suggested. In recent research, we proposed a hybrid rendering model which is applying a proper shading method to each of polygons consisting of an object. The number of polygon for Gouraud shading and that for flat shading should be considered according to a current device performance and system environments. Therefore, this paper suggests the method to calculate automatically a proper resolution of a mesh of object and a proper level of mixture between Gouraud and a flat shading, considering a current device performance and a preference of end-user. The rendering model is so simple that it can be an efficient replacement to reduce a real-time rendering time since it provides automatically multi-level of rendering resolution to an executing environments. Moreover, it can be adopted in real-time adaptive service for 3D graphic contents like a graphic game under various device environments.

• Journal of the Korea Computer Graphics Society
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• v.29 no.3
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• pp.117-125
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• 2023

In the development of clothing design through virtual simulation, it is essential to minimize the differences between the virtual and the real world as much as possible. The most critical task to enhance the similarity between virtual and real garments is to find simulation parameters that can closely emulate the physical properties of the actual fabric in use. The simulation parameter optimization process requires manual tuning by experts, demanding high expertise and a significant amount of time. Especially, considerable time is consumed in repeatedly running simulations to check the results of applying the tuned simulation parameters. Recently, to tackle this issue, artificial neural network learning models have been proposed that swiftly estimate the results of drape test simulations, which are predominantly used for parameter tuning. In these earlier studies, relatively simple linear stiffness models were used, and instead of estimating the entirety of the drape mesh, they estimated only a portion of the mesh and interpolated the rest. However, there is still a scarcity of research on non-linear stiffness models, which are commonly used in actual garment design. In this paper, we propose a learning model for estimating the results of drape simulations for non-linear stiffness models. Our learning model estimates the full high-resolution mesh model of drape. To validate the performance of the proposed method, experiments were conducted using three different drape test methods, demonstrating high accuracy in estimation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.8
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• pp.599-606
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• 2007

An experimental study was performed to measure a ice concentration of ice slurry flowing in a pipe in a real time. In the present paper, we suggested a measuring method by a refractive index and compared it to other methods by a freezing point and a density. To measure the refractive index of the solution, ice particles in the ice slurry should be completely removed and a hydro-cyclone was introduced instead of a mesh. The measuring method through the refractive index coincided with the density method using the real-time solution density within ${\pm}5%$ error range, having the error range less than the other two methods. In the other hand, the measuring method through the density has a good resolution, but the result using the initial density of the solution was different more than 10% error from that using the real-time density. And it has an error range 1.5 times greater than the method through the refractive index.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.10
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• pp.1011-1017
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• 2012

We report the development of an optical micro-nanolithography method by using a roll-type mask. It includes phase-shift lithography and photolithography for realizing various target dimensions. For sub-wavelength resolution, a structure is achieved using the near-field exposure of a photoresist through a cylindrical phase-mask, allowing high-throughput continuous patterning. By using a film-type metal mask, continuous photolithography was achieved, and this method could be used to control the period of resultant patterns in real time by changing the rotating speed of the cylinder mask. As an application, we present the fabrication of a transparent electrode in the form of a metallic mesh by using the developed roll-type photolithography process. As a result, a transparent conductor with good properties was achieved by using a recently built cylindrical phase-shift lithography prototype, which was designed for patterning on 100-mm2 substrates.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.224-229
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• 2004

The objective of this work is not only to perform feasibility studies on the CFD (computational fluid dynamics) analysis for the capillary system design but also to provide an enhanced understanding of the autonomous capillary flow. The capillary flow is evaluated by means of the commercial CFD software of FLUENT, which includes the VOF (volume-of-fluid) model for multiphase flow analysis. The effect of wall adhesion at fluid interfaces in contact with rigid boundaries is considered in terms of static contact angle. Feasibility studies are first performed, including mesh-resolution influence on pressure profile, which has a sudden increase at the liquid/gas interface. Then we perform both 2D and 3D simulations and examine the transient nature of the capillary flow. Analytical solutions are also derived for simple cases and compared with numerical results. Through this work, essential information on the capillary system design is brought out. Our efforts and initial success in numerical description of the microfluidic capillary flows enhance the fundamental understanding of the autonomous capillary flow and will eventually pave the road for full-scale, computer-aided design of microfluidic networks.

• Water for future
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• v.21 no.2
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• pp.183-192
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• 1988

The previous two-dimensional non-linear tidal model of the East China Sea(Choi, 1980) has been further refined to resolve the flow over the ocntinental shelf in more detail. The mesh resolution of the present finite-difference grid system used is 4 minutes latitude by 5 minutes longitude over the entire shelf. The developed fine grid two-dimensional model was utilized to reproduce the $M_2$ tide and $M_4$ tide for the East China Sea contnental shelf. There is general agreement between the model results and the current observation made in the Eastern Yellow Sea, which supports the calculated tidal regime over the shelf. Some preliminary results on maximum bottom stress and tidally-induced residual current were also examined and discussed.

• Journal of Korean Neurosurgical Society
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• v.47 no.3
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• pp.228-231
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• 2010

Posttraumatic syringomyelia may result from a variety of inherent conditions and traumatic events, or from some combination of these. Many hypotheses have arisen to explain this complex disorder, but no consensus has emerged. A 28-year-old man presented with progressive lower extremity weakness, spasticity, and decreased sensation below the T4 dermatome five years after an initial trauma. Magnetic resonance imaging (MRI) revealed a large, multi-septate syrinx cavity extending from C5 to L1, with a retropulsed bony fragment of L2. We performed an L2 corpectomy, L1-L3 interbody fusion using a mesh cage and screw fixation, and a wide decompression and release of the ventral portion of the spinal cord with an operating microscope. The patient showed complete resolution of his neurological symptoms, including the bilateral leg weakness and dysesthesia. Postoperative MRI confirmed the collapse of the syrinx and restoration of subarachnoid cerebrospinal fluid (CSF) flow. These findings indicate a good correlation between syrinx collapse and symptomatic improvement. This case showed that syringomyelia may develop through obstruction of the subarachnoid CSF space by a bony fracture and kyphotic deformity. Ventral decompression of the obstructed subarachnoid space, with restoration of spinal alignment, effectively treated the spinal canal encroachment and post-traumatic syringomyelia.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.395-402
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• 2006

In analyzing the nano-scale phenomena or behaviors of nano devices or materials, it is often desirable to deal with more atoms than can be treated only with a full atomistic simulation. However, even now, it is advisable to apply the atomistic simulation to the narrow region where the deformation field changes rapidly but to apply the conventional continuum model to the region far from that region. This equivalent continuum model can be formulated by applying the Cauchy-Born rule to the exact atomistic potential as in the quasicontinuum method. To couple the atomistic model with the equivalent continuum model, continuum displacements are conformed to the molecular displacements at the discrete positions of the atoms within the bridging domain. To satisfy the coupling constraints, we apply the Lagrange multiplier method. The continuum model in the bridging model should be applied on the region where the deformation field changes gradually. Then we can make the nodal spacing in the continuum model be much larger than the atomic spacing. In the first step, we generate the atomic-resolution mesh with the nodal spacing equal to the atomic spacing, and then we eliminate the nodal degrees of freedom adaptively using the node deactivation techniques. We eliminate more DOFs as the regions are more far from the atomistic region. Computing time and computational resources can be greatly reduced by the present node deactivation technique in multi scale analysis.

• Solar Energy
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• v.17 no.3
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• pp.59-66
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• 1997

The present study adopted the PTV method for the velocity acquisition. The system consists of an image grabber built-in a personal computer and a laser-based sheet light projector and particle identification softwares. Velocity vectors are obtained, by PTV and they are used as velocity components for Poisson equation for pressure. Related boundary conditions and no-slip condition at solid wall and the linear velocity extrapolation on the upper side of cavity are well examined for the present study. For calculation of pressure, resolution of grid is basically $40{\times}40$ and 2-dimensional uniform mesh using MAC staggered grid is adopted. The result of experiment reveal that, newly suggested measuring method is capable of estimating pressure and velocity distribution of flow field reasonably.