• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.759-762
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• 2000

Rapid Prototyping (RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain RP apparatus. The objective of this study is to develop and design a new RP process, Variable Lamination Manufacturing using expandable polystyrene foam sheet as part material (VLM-S), which can make up for the disadvantage of existing techniques, and to develop an apparatus to implement the process. In order to examine the possibility of practical utilization of the proposed VLM-S process for prototyping of a general three-dimensional shape, an auto-shift lever knob and a pyramid shape were fabricated.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.309-314
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• 2007

Optimal layer sequencing of a multi-layered acoustical foam is solved to maximize its sound transmission loss. A foam consisting of air and poroelastic layers can be optimized when a limited amount of a poroelastic material is allowed. By formulating the sound transmission loss maximization problem as a one dimensional topology optimization problem, optimal layer sequencing and thickness were systematically found for several frequencies. For optimization, the transmission losses of air and poroelastic layers were calculated by the transfer matrix derived from Biot's theory. By interpolating five intrinsic parameters among several poroelastic material parameters, dear air-poroelastic layer distributions were obtained; no filtering or post-processing was necessary. The optimized foam layouts by the proposed method were shown to differ depending on the frequency of interest.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.474-479
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• 1998

In this paper, the structural behavior of R.C. multi-layered floor structure including foam concrete layer is numerically analyzed. For the analysis, 3D interface element has been implemented to finite element analysis program to consider the interfacial behavior of multi-layered floor structure which consists of rubber layer, foam concrete layer and mortar layer on RC slab. Based on analysis results on multi-layered structure, its structural behavior is analyzed according to geometrical and material properties of foam concrete. Optimum material property of each layer of the floor structure is proposed to get optimum multi-layered concrete structure.

• Polymer(Korea)
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• v.29 no.3
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• pp.300-303
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• 2005

Polyurethane multi-layer and foam multi-layer were prepared with PU1000 and PU2000 made by poly(propylene glycol) (PPG) having the molecular weight of 1000 and 2000 g/mol, respectively. The damping and transmission loss of these materials were compared with PU1000 used as a reference. The damping peak of polyurethane multi-layer was shifted to the lower temperature compared with PU1000, while the damping peak of polyurethane foam multi-layer was shifted to the higher temperature and broaden. In terms of noise reduction, the transmission loss of polyurethane multi-layer was effective at the specific frequency range such as less than 100 Hz and around 600 Hz compared with PU1000. The transmission loss of polyurethane foam multi-layer was most effective in the whole experimental frequency range.

• Fire Science and Engineering
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• v.34 no.2
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• pp.7-13
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• 2020

In this study, water glass was applied as a coating material to a rigid polyurethane foam to improve the flame-retardant properties of the foam. The heat release rate of the cone calorimeter of the urethane foam, in which the inorganic water-glass coating layer was applied, decreased rapidly. The water glass coated on the polyurethane surface formed a glassy foam by foaming with water, which did not escape during the vitrification reaction when the foam or glass was heated. The glassy foam formed on the polyurethane foam became a fire-resistant insulation layer that inhibited the combustion of the polyurethane foam for more than 10 min. Water glass was found to improve the flame-retardant properties of the rigid polyurethane foam.

• Steel and Composite Structures
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• v.51 no.1
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• pp.53-61
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• 2024

Aluminum foams sandwich panel (AFSP) has been used in engineering field, where cyclic loading is used in most of the applications. In this paper, the fatigue life of AFSP prepared by the bonding method was investigated through a three-point bending test. The mathematical statistics method was used to analyze the influence of different plate thicknesses and core densities on the bending fatigue life. The macroscopic fatigue failure modes and damage mechanisms were observed by scanning electron microscopy (SEM). The results indicate that panel thickness and core layer density have a significant influence on the bending fatigue life of AFSP and their dispersion. The damage mechanism of fatigue failure to cells in aluminum foam is that the initial fatigue crack begins the cell wall, the thinnest position of the cell wall or the intersection of the cell wall and the cell ridge, where stress concentrations are more likely to occur. The fatigue failure of aluminum foam core usually starts from the semi-closed unit of the lower layer, and the fatigue crack propagates layer by layer along the direction of the maximum shear stress. The results can provide a reference for the practical engineering design and application of AFSP.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.191-195
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• 2009

In the solid rocket propellant combustion, dynamic phase change from solid to liquid to vapor occurs across the melt layer. During the burning surface, micro scale bubbles form as liquid and gas phases are mixed in the intermediate zone between the propellant and the flame. The experimentally measured thickness of this layer called the foam layer is approximately 1 micron at 1 atmosphere. In this paper, we present a new melting layer model derived from the classical phase change theory. The model results show that the surface of burning grows and propagate uniformly at a velocity of $r=ap^n$.

• Steel and Composite Structures
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• v.23 no.1
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• pp.107-114
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• 2017

Design of stepwise foam claddings subjected to air-blast is performed based on random Voronoialgorithm. FE models are constructed using the random Voronoialgorithm, and numerical analysis is carried out to simulate deformation mode and energy absorption of the cladding by the ABAQUS/Explicit software. The FE model is validated by test result, and good agreement is achieved. The deformation patterns are presented to give an insight into the influences of distribution on deformation mechanisms. The energy absorbed by the stepwise foam cladding is examined, and the parameter effects, including layer number, gradient, and blast loading, are discussed. Results indicate that the energy absorption capacity increases with the number of layer, gradient degree, and blast pressure increasing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.763-766
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• 2000

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stackin, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain RP apparatus. The objective of this study is to develop software for automatic generation of unit shape part (USP) for a new RP process, Variable Lamination Manufacturing using linear hotwire cutting technique and expandable polystyrene foam sheet as part material (VLM-S). In order to examine the applicability of the developed software to VLM-S, USP's of general three-dimensional shapes, such as an auto-shift lever knob and a pyramid shape were generated.

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.121-124
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• 2010

Thermal burn occurred in the anesthetized dog as a result of using hot pack to treat hypothermia. After hospital discharge, thermal burn leaded to secondary infection due to dog bites of the other dog in the house. After secondary infection, the treatment was performed with medication and bandaging. Because of the pain and infection from the wound, carprofen (2 mg/kg bid) and amoxicillin (20 mg/kg bid) were administrated orally for 40 days. And for 35 days, wet-to-dry gauze dressing was used to absorb purulent exudate. During this period, the burn eschar was removed completely from the burn site. After 35 days, the hydrophilic polyurethane foam ($Medifoam^{(R)}$, Ildong Pharm, Co., Korea) was admitted to the burn site for 30 days. $Medifoam^{(R)}$ made healing rate of the wound faster because the inner layer did not adhered to the wound, and newly formed tissue was protected. The second layer, hydrophilic absorptive layer absorbed excessive fluid and kept the wound surface moist. After 65 days after thermal burn, the wound was healed completely.