• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.483-487
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• 2011

In the present study, a CFD program based on a finite volume method was developed by using an unstructured polyhedral grid system for the accurate simulation with the complex geometry of computational domain. To simulate the transient flow induced by the moving solid object, the program used a fractional step method and a ALE (Algebric Lagrangian-Eulerian) method. The grid deformation for the moving of solid object were performed with a spring analogy based on the center coordinate of each computational grid. To verify the present program with these methodologies, the numerical results of the flow around the fixed and oscillating circular cylinder were compared with the previous numerical results.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.28-32
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• 2003

Thermo-mechanical behavior of a ceramic ball grid array(CBGA) package assembly and wire bond ball grid array(WB-PBGA) package assemblies are characterized by high sensitive moire interferometry. Moire fringe patterns are recorded and analyzed at various temperatures in a temperature cycle. Thermal-history dependent analyses of global and local deformations are presented, and bending deformation(warpage) of the package and shear strain in the rightmost solder ball are discussed. A significant non-linear global behavior is documented due to stress relaxation at high temperature. The locations of the critical solder ball in WB-PBGA package assemblies are documented.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.1-11
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• 1995

A numerical shallow water wave deformation model to solve unsteady mild slope equation was develope(1. The energy equation of Izumiya and Horikawa(1984) for wave breaking and bottom friction was incorporated to estimate more realistically energy damping resulted from wave breaking and reflection. A numerical scheme for variable grid spacings was also introduced to complement the defect of unsteady mild slope equation limiting the grid spacings. This model was tested and compared with the existing analytic solutions and physical modelings, and applied to a practical situation.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.29-34
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• 2010

Nanoimprint lithography (NIL) is an emerging technology enabling cost effective and high throughput nanofabrication. To successfully imprint a nanometer scale patterns, the understanding of the mechanism in nanoimprint forming is essential. In this paper, a numerical analysis of polymer flow in thermal NIL was performed. First, a finite element model of the periodic mold structure with prescribed boundary conditions was established. Then, the volume of fluid (VOF) and grid deformation method were utilized to calculate the free surfaces of the polymer flow based on an Eulerian grid system. From the simulation, the velocity fields and the imprinting pressure for constant imprinting velocity in thermal NIL were obtained. The velocity field is significant because it can directly describe the mode of the polymer deformation, which is the key role to determine the mechanism of nanoimprint forming. Effects of different mold shapes and various thicknesses of polymer resist were also investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1051-1057
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• 2013

In this study, an automatic surface-strain measurement system called "ASIAS-bio" has been developed. This system can be used even in cases in which it is very difficult to apply a regular grid pattern necessary for measuring surface-strain, such as curved or uneven surfaces; surfaces damaged by corrosion or contamination; or soft materials such as rubber, foam, and biological tissues. This system works independently of the measurement conditions including the material and its surface condition, grid pattern and size, grid marking method, and degree of deformation. A comparison between the strain distributions of the sheet metal parts measured by using this system and those obtained by a commercial system showed that this system was sufficiently reliable. In addition, the deformation of the swine joint capsule and human knee skin was measured by using this system to demonstrate its usefulness.

• Geomechanics and Engineering
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• v.35 no.6
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• pp.617-626
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• 2023

In this study, three-dimensional numerical parametric study was conducted to explore deformation mechanisms of grouped piled-raft-foundation due to lateral load in clays. Effects of load intensity, loading angle, soil stiffness, pile diameter, pile spacing and pile length on foundation deformations were explored. It is found that the smallest and largest movements of pile foundation are induced when the loading angles are 0° and 30°~60°, respectively. By increasing loading angle from 0° to 30°~60°, the resultant horizontal movements and settlements increase by up to 20.0% and 57.1%, respectively. Since connection beams can substantially increase integrity of four piled raft foundation, resultant horizontal movements, settlements and bending moments induced in the piled raft foundation decrease by up to 54.0%, 8.8% and 46.3%, respectively. By increasing soil stiffness five times, resultant horizontal movements and settlements of pile foundation decrease by up to 61.7% and 13.0%, respectively. It is indicated that effects of connection beam and soil stiffness on settlements of pile foundation are relatively small. When pile diameter is less than 1.4 m, deformations of piled raft foundation decrease substantially as a reduction in the pile diameter. Two dimensional groups are proposed to develop calculation charts of horizontal movements and settlements of pile foundation. The proposed calculation charts can directly estimate movements of piled raft foundation under arbitrary loading, ground and pile conditions.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.1-8
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• 2003

Thermo-mechanical behavior of a ceramic ball grid array (CBGA) package assembly are characterized by high sensitive moire interferometry. Moir fringe patterns are recorded and analyzed at various temperatures in a temperature cycle. Thermal-history dependent analyses of global and local deformations are presented, and bending deformation (warpage) of the package and shear strain in the rightmost solder ball are discussed. A significant non-linear global behavior is documented due to stress relaxation at high temperature. Analysis of the solder interconnections reveals that inelastic deformation accumulates on only eutectic solder fillet region at high temperatures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.275-282
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• 2007

In this study, a fluid-structure interaction (FSI) analysis system has been developed in order to evaluate the turbine cascade performance with blade structural deformation effect. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. To consider the deformed position of rotor airfoil, dynamic moving grid method is applied. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-{\varepsilon}$ turbulence models are solved to predict unsteady fluid dynamic loads. A fully implicit time marching scheme based on the Newmark direct integration method with high artificial damping is used to compute the fluid-structure interaction problem. Cascade performance evaluations for different elastic axis positions are presented and compared each other. It is importantly shown that the predicted aerodynamic performance considering structural deformation effect of blade can show some deviations compared to the data generally computed from rigid blade configurations and the position of elastic axis also tend to give sensitive effect.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.121-121
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• 1992

Deformation behavior of compatible polymer blends was studied using scanning electron, optical, and transmission electron microscopies. Four different compatible systems were employed and charaterized in this investigation : polystyrene(PS) and polyphenylene oxide(PPO), polystyrene(PS) and polyvinlmethylether(PVME), polystyrene(PS) and poly $\alpha$-methylstyrene(P$\alpha$MS). Individual craze and shear deformation zone microstructures were examined by transmission microscopy (TEM). For TEM observations, specimens deformed in-situ on a TEM grid were utilized. Quantiative analysis of these crazes and shear deformation zones was obtained from the nicrodensitometry of the TEM negatives in the manner developed by Lauterwasser and Kramer. Microdensitometry resulys showed that the fibril extension ratio decreased as the PPO content increased in the PS/PPO blends, and finally, for 100% PPO, only shear deformation zones were observed. For the PS/PVME blends, the ribril extension ratio also decreased as the VME content increased. For the PS/P$\alpha$MS blends, the fibril extension ratio increased as the P$\alpha$MS content increased, For the PPO/P$\alpha$MS blends, the fibril extension ratio increased as the P$\alpha$MS content increased.

• Journal of the Korean Society of Visualization
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• v.19 no.3
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• pp.77-83
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• 2021

Solid oxide fuel cell (SOFC) operates at high temperatures in range of 600-800℃. Since layers of SOFC are composed of different substances, different thermal expansion in SOFC can result in defects under high temperature conditions. For understanding relation between temperature field and the thermal deformation in SOFC, temperature and strain field were simultaneously estimated using thermographic phosphors by optical measurement. Temperature fields were obtained by the life-time method, and the temperature differences of one specimen was checked with thermocouple. The thermal deformation was estimated by digital image correlation (DIC) method with extracted phosphorescence images. To investigate the deformation accuracy of DIC measurement, thermographic phosphors were coated with and without grid pattern on aluminum surface. Simultaneous measurement of temperature fields and thermal deformation were carried out for YSZ. This study will be helpful to multi-sensing of temperature field and thermal deformation on SOFC cells.