• Design & Manufacturing
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• v.17 no.4
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• pp.42-51
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• 2023

In this study, we investigated the injection molding technology of thick-walled light guides, which are parts that control the light source of automotive lamps. Through injection molding analysis, the gate position that can minimize product shrinkage and deformation was selected, and a mold reflecting the analysis results was manufactured to evaluate the effect of injection speed and holding pressure on transferability during micro-pattern molding through experiments. When designing an injection mold for products with varying thicknesses, it was found that installing the gate on the side of the thicker part was advantageous for reducing volume shrinkage and deformation. It was found that the effect of shrinkage due to thickness may be greater than the position of the gate on pattern transferability. The pattern transfer error decreased as the injection speed and holding pressure increased, and it was found that increasing the injection speed was relatively effective.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.181-184
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• 2001

The biological fixation of carbon dioxide using microalgae have many advantages over chemicals and remove carbon dioxide simultaneously. A ketocarotenoid astaxanthin is hyper-accumulated in the green freshwater microalga, Haematococcus pluvialis. In the present study, the combine effects of carbon dioxide concentration and light intensity on the growth of H. pluvilais were investigated. The carbon dioxide concentration above 10% caused a severe inhibition and around 5% is optimal for growth. Adaptation to high concentration of carbon dioxide enhanced the $CO_2$ tolerance. Specific growth rate calculated differently based upon cell number or dry weight because of the distinctive life cycle patterns of H. pluvialis : small-sized motile green cell and thick cell walled red cyst cell. Based on the light dependence of H. pluvialis, internally illuminated air-lift photobioreactor was designed and operated. Gradual increase of light supply gave more active growth and more effective productivity of astaxanthin than constant light supply.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.1 s.244
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• pp.76-83
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• 2006

This paper addresses the method for the shape design sensitivity analysis of the buckling load in the continuous elastic body. The sensitivity formula for critical load is analytically derived and expressed in terms of shape variation, based on the continuum formulation of the stability problem. Though the buckling problem is more efficiently solved by the structural elements such as beam and shell, the elastic solids are considered in this paper because the solid elements can be used in general for any kind of structures whether they are thick or thin. The initial stress and buckling analysis is carried out by the commercial analysis code ANSYS. The sensitivity is computed by using the mathematical package MATLAB using the results of ANSYS. Several problems including straight and curved beams under compressive load, ring under pressure load, thin-walled section and bottle shaped column are chosen to illustrate the efficiency of the presented method.

• Transactions of Materials Processing
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• v.11 no.4
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• pp.355-362
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• 2002

In this study, an axi-symmetric finite element program for elastic analysis of the die set shrink fitted in cold extrusion was developed. The geometrical constraint according to shrink fit was enforced by employing the Lagrange multiplier method. The numerical results for strain and stress distributions in the die set including single and multi stress rings assembled by shrink fit were compared well with the Lame's equation for thick-walled solution available in the literature. To extend the applicability of the analysis program developed, various cases without or with stress ring and with pre-stress applied on stress ring were numerically investigated as well. This numerical approach enables the optimization study to determine optimal dimensions of die set to improve tool life for practical use in industry.

• Journal of the Korea Furniture Society
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• v.18 no.2
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• pp.100-105
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• 2007

In this report, we describe the anatomical features of Gmelina arborea Roxb. belong to the genera of Verbenaceae native to Bangladesh and safranine penetration depth in radial and longitudinal directions. The wood of this species was characterized mostly by distinct growth ring boundaries, diffuse-porous, simple perforations, alternate non-vestured intervessel pits, and relatively short vessel elements and medium fibers. Thin to thick walled septate fibers with simple to minutely bordered pits are confined to the radial walls. Tyloses are common. They are paratracheal axial parenchyma vascicnetric and confluent. Rays not higher than 1milimeter are found, and larger rays commonly 4 to 5 seriate are dominantly present, as are multi seriate rays composed of a procumbent ray with 1 row of square or upright cells. Acicular crystals are present in ray cells. Another experiment was taken under consideration to observe the liquid penetration depth in longitudinal and radial directions using safranine. It was found that safranine penetrated easily in longitudinal direction and sapwood was more permeable than heartwood.

• Steel and Composite Structures
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• v.13 no.4
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• pp.383-396
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• 2012

In order to develop a verification method for extremely low cycle fatigue (ELCF) of steel structures, the initiation mechanism of ductile cracks is investigated in the present study, which is the first step of brittle fracture, occurred in steel bridge piers with thick-walled sections. For this purpose, a total of six steel columns with small width-thickness ratios were tested under cyclic loading. It is found that ductile cracks occurred at the column base in all the specimens regardless of cyclic loading histories subjected. Moreover, strain history near the crack initiation location is illustrated and an index of energy dissipation amount is proposed to evaluate deformation capacity of structures.

• Structural Engineering and Mechanics
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• v.2 no.3
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• pp.245-256
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• 1994

A new axisymmetric crack model is proposed on the basis of p-version of the finite element method limited to theory of small scale yielding. To this end, axisymmetric stress element is formulated by integrals of Legendre polynomial which has hierarchical nature and orthogonality relationship. The virtual crack extension method has been adopted to calculate the stress intensity factors for 3-D axisymmetric cracked bodies where the potential energy change as a function of position along the crack front is calculated. The sensitivity with respect to the aspect ratio and Poisson locking has been tested to ascertain the robustness of p-version axisymmetric element. Also, the limit value that is an exact solution obtained by FEM when degree of freedom is infinite can be estimated using the extrapolation equation based on error prediction in energy norm. Numerical examples of thick-walled cylinder, axisymmetric crack in a round bar and internal part-thorough cracked pipes are tested with high precision.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.215-218
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• 1999

A general structural model, which is an extension of the Vlassov theory, is developed for the analysis of composite rotor blades with elastic couplings. A comprehensive analysis applicable to both thick-and thin-walled composite beams, which can have either open- or closed profile is formulated. The theory accounts for the effects of elastic couplings, shell wall thickness, and transverse shear deformations. A semi-complementary energy functional is used to account for the shear stress distribution in the shell wall. The bending and torsion related warpings and the shear correction factors are obtained in closed form as part of the analysis. The resulting first order shear deformation theory describes the beam kinematics in terms of the axial, flap and lag bending, flap and lag shear, torsion and torsion-warping deformations. The theory is validated against experimental results for various cross-section beams with elastic couplings.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.154-159
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• 2008

Angioleiomyoma of the sinonasal tract is a rare benign tumor. We report a case of angioleiomyoma of the nasal septum in a 51-year-old woman who complained of frequent epistaxis for 3 months. Surgicalexcision was performed. The excised specimen was $0.7{\times}0.5{\times}0.4cm$ in size, well circumscribed, grayish white, rubbery, and soft. Histological examination showed thick-walled blood vessels and smooth muscle cell proliferation. No nuclear atypia or mitoses were present.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.841-846
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• 2006

This paper addresses the method for the shape design sensitivity analysis of the buckling load in the continuous elastic body. The sensitivity formula for critical load is analytically derived and expressed in terms of shape variation, based on the continuum formulation of the stability problem. Though the buckling problem is more efficiently solved by the structural elements such as beam and shell, the elastic solids are considered in this paper because the solid elements can be used in general for any kind of structures whether they are thick or thin. The initial stress and buckling analysis is carried out by the commercial analysis code ANSYS. The sensitivity is computed by using the mathematical package MATLAB using the results of ANSYS. Several problems including straight and curved beams under compressive load, ring under pressure load, thin-walled section are chosen to illustrate the efficiency of the presented method.