• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.159-167
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• 1999

For exisiting $K_0$-oedometer, the lateral wall of the ring is cut thinly to make space and by filling the space with space with water or mercuty to keep the balance to the lateral pressure of a specimen, the pressure of the fluid is checked for the pressure of the specimen. But the devices to keep the balance to the lateral pressure of a specimen are complicated, difficult to manufacture and expensive. As newly developed $K_0$-oedometer is equipped with the load cell which can resist higher pressute than the lateral pressure of the specimen, there is nearly no deformation due to the lateral pressure of the specimen. And the measuting is cheap and easy as there are fewer accessories.

• Journal of the Mineralogical Society of Korea
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• v.4 no.2
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• pp.90-98
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• 1991

This study introduces a new structural model of 1M 2:1 trioctahedral clay minerals or, more generally, 2:1 trioctahedral phyllosilicates. The structural model requires only the chemical formulae of the clay minerals as an input and uses the regression relation (Radoslovich, 1962) to calculate the a- and b-dimensions of the phyllosilicates with the given chemical formulae. The atomic coordinates of the constituent atoms are geometrically calculated for C2/m space group under the assumption that the interatomic distances are constant. To determine the c-dimension, this study calculates the binding energies of 1M 2:1 trioctahedral phyllosilicates as a function of d(001) and find the minimum energy producing d(001). The structural model generates the cell dimensions, interaxial angles, interatomic distances, octahedral, tetrahedral and interlayer thickness, polyhedron deformation angles and atomic coordinates in the unit cell. The simulated structural parameters of phlogopite and annite are very close to the reported data by Hazen and Burnham (1973), suggesting that the structure simulation using only the chemical formule is successful, and thus, that the structural model of this study overcomes the difficulties in the previous models by other investigators.

• Coupled systems mechanics
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• v.10 no.6
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• pp.521-544
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• 2021

In this work, we present the development of a 3D lattice-type model at microscale based upon the Voronoi-cell representation of material microstructure. This model can capture the coupling between mechanic and electric fields with non-linear constitutive behavior for both. More precisely, for electric part we consider the ferroelectric constitutive behavior with the possibility of domain switching polarization, which can be handled in the same fashion as deformation theory of plasticity. For mechanics part, we introduce the constitutive model of plasticity with the Armstrong-Frederick kinematic hardening. This model is used to simulate a complete coupling of the chosen electric and mechanics behavior with a multiscale approach implemented within the same computational architecture.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2493-2499
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• 2011

With growth of nano-bio industry, it is of significant importance to develop an automated system to exploit cell behaviors, including migration, mitosis, apoptosis, shape deformation of individual cells and their interactions among cells in the process of cell growth. In this paper, we proposed preprocessing techniques, a classification method which classifies clusters (overlapping multiple cells) from cells and an automated method which counts the number of cells and clusters in order to analyze 2D or 3D deformations of the cells in the real-time images from microscope in the cell culture. We conducted the 3T3 cell images taken from each thirty-minute interval. It showed the average 99.8% accuracy automatically for separating cells and clusters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.22-29
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• 2004

Deformation of the porous media has influence on performance of a proton exchange membrane fuel cell (PEMFC). The stress distributions and deformation of the porous media are major factors for safe and efficient operation in the PEMFC. In this paper, nonlinear contact analysis of air plate and porous media is performed under a working condition to predict the performance characteristics of the air plates. Two kinds of models are suggested for this study. The first porous media model has nonlinear material properties. The second model has nonlinear material properties with contact condition between porous media and air plate. The numerical analysis results of the two models are somewhat different. It is shown that the nonlinear contact analysis is required for the design study of the PEMFC.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.133-140
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• 2004

The histopathologieal effects of his(tri-n-butyltin)oxide (TBTO) on the flounder, Paralichthys otivaceus were examined by means of histological methods. The experimental fishes were exposed to 0.17, 0.36, 0.60, 3.20, 6.30, 12.50 ${\mu}g \;L^{-1}$TBTO concentrations for 42 days. Histopathological change of the fish exposed to TBTO is dependent on the exposure duration and concentration. In the lower concentrations early histological changes included activated mucous cells and chloride cells, capillary hyperemia and epithelial hyperplasia in the gill; hepatocyte activation, degeneration of bile duct and pancyeatic zymogen reduction in the hepatopancreas; and capillary hyperemia, appearance of eosinophilic cell and melano-macrophagocytes in the kidney. At the higher concentrations histological changes of dysfunctionality included epithelial lifting and deformation of the lamellae in the gill; pycnosis and cytoplasmic degeneration of hepatocyte; pycnosis of haemopoietic cell and deformation of renal tubules and glomerulus in the kidney. It is indicated that TBTO induced histopathological changes in the fish as other aquatic pollutants.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.444-450
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• 2010

In the present study, the microscopic degradation of copper and copper alloy subjected to cyclic deformation has been evaluated by the electrical resistivity measurement using the DC four terminal potential method. The copper (Cu) and copper alloy (Cu-35Zn), whose stacking fault energy is much different each other, were cyclically deformed to investigate the response of the electrical resistivity to different dislocation substructures. Dislocation cell substructure was developed in the Cu, while the planar array of dislocation structure was developed in the Cu-35Zn alloy increasing dislocation density with fatigue cycles. The electrical resistivity increased rapidly in the initial stage of fatigue deformation in both materials. Moreover, after the fatigue test it increased by about 7 % for the Cu and 6.5 % for the Cu-35Zn alloy, respectively. From these consistent results, it may be concluded that the dislocation cell structure responds to the electrical resistivity more sensitively than the planar array dislocation structure evolved during cyclic fatigue.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.34-41
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• 2014

The goal of this study is to investigate some crack behaviors which affect the crack propagation angle at the planar solid oxide fuel cell with cracks under the fabricating and operating temperature and analyze the stresses by 3 steps processing on the solid oxide fuel cell. Currently, there are lots of researches of the performance improvement for fuel cells, and also for the more powerful efficiency. However, the planar solid oxide fuel cell has demerits which the electrode materials have much brittle properties and the thermal condition during the operating process. It brings some problems which have lower reliability owing to the deformation and cracks from the thermal expansion differences between the electrolyte, cathode and anode electrodes. Especially the crack in the corner of the electrodes gives rise to the fracture and deterioration of the fuel cells. Thus it is important to evaluate the behavior of the cracks in the solid oxide fuel cell for the performance and safety operation. From the results, we showed the stress distributions from the cathode to the anode and the effects of the edge crack in the electrolyte and the slant crack in the anode. Futhermore the crack propagation angle was expected according to the crack length and slant angle and the variation of the stress intensity factors for the each fracture mode was shown.

• Journal of Aquaculture
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• v.12 no.2
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• pp.155-161
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• 1999

In order to obtain the basic information for seeding production of Echiuroid worm, Urechis unicinctus, the influence of pH and salinity on egg development was investigated. Mature adult of U. unicinctus were collected at the Diving Cooperation of Yosu in Korea and reared during 5 weeks. We carried out the artificial insemination in the laboratory on Dec. 29, 1998, and reared the embryo under different pH and salinity. Treatments were carried out with different pH(4~10) and salinity($0~45\textperthousand$). Embryos in pH 4, salinity $0\textperthousand$, $10\textperthousand$, $40\textperthousand$ and $45\textperthousand$ tanks did not develope after fertilization and became deformed or dead, before swimming embryo. In these pH and salinity conditions, deformation rate of embryo was high at 8-cell stage and 16-cell stage. But embryos in pH 5~10, salinity $20~35\textperthousand$ tanks developed into swimming embryo stage. These result indicate that an echiuran inhabits in both intertidal and subtidal mudflates. After fertilization, sixteen-cell stage took 5.3~5.6 hours in pH 5~10 tanks, and 5.1~5.8 hours in $20~35\textperthousand$ tanks. And swimming embryo took 13.3~ 14.1 hours in all conditions. The desirable pH and salinity for egg development were 7~8 and $30\textperthousand$, respectively.

• Elastomers and Composites
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• v.50 no.1
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• pp.30-34
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• 2015

Thermo-mechanical treatment process of a compressed open-cell rigid polyurethane foam (OC-RPUF), which was fabricated for the vacuum insulation panel (VIP), was studied to obtain an optimum condition for the dimensional stability by the relaxation of compressive stress. Thermo-mechanical deformation of the sample OC-RPUF was shown to occur from about $120^{\circ}C$. Yield stress of 0.36 MPa was shown at about 10% yield strain. And, densification of the foam started to occur from 75% compressive strain and could be continued up to max. 90%. Compression set of the sample restored after initial compression to 90% at room temperature was ca. 82%. Though the expansion occurred to about twice of the originally compressed thickness in case of temperature rise to $130^{\circ}C$, it could be overcome and the dimensional stability could be maintained if the constant load of 0.3 MPa was applied. As the result, a thermo-mechanical treatment process, i.e, annealing process at temperature of $130{\sim}140^{\circ}C$ for about 20 min as is the maximum compressed state at room temperature, should be required for dimensional stability as an optimum condition for the use of VIP core material.