• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.69-75
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• 2008

Shear tests were carried out on interface between two concrete eco-blocks which comprise segmental retaining wall. Three interface conditions were considered : 1) direct contact of two blocks, 2) placing rubber pad between two blocks, 3) placing rubber pad and shear key between two blocks. According to shear tests, shear load-shear displacement relationship which was obtained from direct contact of two blocks was similar to elastic-perfectly plastic behavior. Ductile behavior of shear load-shear displacement relationship was observed for the interface condition of placing rubber pad. Apparent minimum shear capacities and apparent friction angles for the interface conditions of direct contact of two blocks, placing rubber pad between two blocks, placing rubber pad and shear key were 1.7 kN/m, $27.6^{\circ}$ and 4.2 kN/m, $26.2^{\circ}$ and 20.9 kN/m, $26.0^{\circ}$ respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.499-502
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• 2005

A process map has been developed, which can identify the process conditions for weak mechanical bonding at the contact surface during the direct extrusion of a Cu-Ti bimetal bar. Bonding mechanism between Cu and Ti was assumed as a cold pressure welding. Then, the plastic deformation at the contact zone causes mechanical bonding and a new bonding criterion for pressure welding was developed as a function of the principal stretch ratio and normal pressure at the contact surface by analyzing micro local extrusion at the contact zone. Finite element analyses for extrusion of Cu-Ti bimetal bars were performed for various process conditions. The deformation history at the contact surface was traced and the proposed new bonding criterion was applied to predict whether the mechanical bonding at the Cu-Ti contact surface happens. Finally, a process map for the extrusion of Cu-Ti bimetal bar is suggested.

• Journal of the Korean Home Economics Association
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• v.50 no.5
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• pp.115-124
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• 2012

The purpose of this study was to investigate the mediating effects of parental neglect on the relationship between family environment, such as economic status and harmony of family and contact with harmful environments. The data came from the 2009 Korean Survey on the Rights of Youth (N = 6,601). The data was analyzed using Structural Equation Modeling by means of SPSS 17.0 and AMOS 7.0. Bootstrap method used to test significant mediating effects. We found that family environment influences an adolescent's contact with harmful environments through parental neglect, showing that family environment has both indirect and direct effects. The results suggested that a family with low socio-economic status and more stress than harmony engenders a negative effect on the behavior of parents providing care and affection. This neglect influences the adolescent's contact with harmful environments such as harmful media and facilities. It must be acknowledged that parental care and suitable affection play a minimal role in adolescent's contact with harmful environments.

• Tribology and Lubricants
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• v.14 no.1
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• pp.23-27
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• 1998

The characteristics of friction in direct acting OHC vane train system have been investigated by the comparison of experimental and theoretical results. A modified friction model was presented to calculate the friction force at cam/tappet contact. A simple experimental system was evaluated to measure the friction force and the camshaft driving torque. The friction force was measured by using the dynamic loadcell. Good agreement was found between theoretical and experimental results in friction force, but there was a little difference in driving torque.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1561-1563
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• 2008

We report an optical second harmonic generation measurement that allows direct probing of dynamical carrier motion in organic field effect transistors. Carrier injection and transport process are discriminated. The mobility and contact resistance of pentacene FETs are determined from the visualized diffusion-like carrier motion.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.43-46
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• 2008

This paper proposes an advanced test circuit for detecting the connectivity between a drum ring of laser printer and PCB. The detection circuit of charge sharing is proposed, which minimizes the influences of internal parasitic capacitances. The test circuit is composed of precharge circuit, analog comparator, level shifter. Its functional operation is verified using $0.6{\mu}m$ 3.3V/40V CMOS process parameter by HSPICE. Access time is100ns. Layout of the drum contact test circuit is $465{\mu}m\;{\times}\;117{\mu}m$.

• Journal of Korean Association for Spatial Structures
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• v.13 no.1
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• pp.8-16
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• 2013

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.875-877
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• 2007

Zinc tin oxide (ZTO) sol-gel solution was synthesized for ink-jet printable semiconducting ink. Bottom-contact type TFT was produced by printing the ZTO layer between the source and drain electrodes. The transistor involving the ink-jet printed ZTO had the $mobility\;{\sim}\;0.01\;cm^2V^{-1}s^{-1}$. We demonstrated the direct-writing of semiconducting oxide for solution processed TFT fabrication.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.33-41
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• 2011

This study presents modeling technologies applicable to an unbonded post-tension system using a finite element software package. In this study, both direct modeling method and multiple spring method were used. The direct modeling method adopts tube-to-tube contact elements to represent the physical feature of a post-tension system. The multiple spring method uses virtual tendons attached to the real tendons using a number of rigid axial springs that freely rotate at the ends. Both modeling technologies provide accurate predictions. However, only the multiple spring method provides numerically stable and reliable responses with a consideration of concrete tension stiffening effects. Therefore, the multiple spring method turned out to be a generally applicable modeling technology for the unbonded post-tension system. Comparisons were made for the analytical and experimental results for the verification of the selected method, and parameter studies were carried out to confirm the appropriateness of the modeling assumptions and parameters adopted in the analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2245-2252
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• 2002

Design sensitivity analysis scheme is proposed in an elasto -plastic finite element method with explicit time integration using a direct differentiation method. The direct differentiation is concerned with large deformation, the elasto-plastic constitutive relation, shell elements with reduced integration and the contact scheme. The design sensitivities with respect to the process parameter are calculated with the direct analytical differentiation of the governing equation. The sensitivity results obtained from the present theory are compared with that obtained by the finite difference method in a class of sheet metal forming problems such as hemi-spherical stretching and cylindrical cup deep-drawing. The result shows good agreement with the finite difference method and demonstrates that the preposed sensitivity calculation scheme is a pplicable in the complicated sheet metal forming analysis and design.