• Carbon letters
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• v.2 no.2
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• pp.99-104
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• 2001

Partial mesophase (PM) pitch precursor was prepared from fluidized catalytic cracking-decant oils (FCC-DO) by chemical reaction in the presence of $Br_2$. The PM pitch heated-treatment at $420^{\circ}C$ for 9 h exhibited the softening point of $297^{\circ}C$ with 23% yield, and 55% anisotropic content. The PM pitch precursor was melt-spun through circular nozzle by pressurized $N_2$, stabilized at $310^{\circ}C$, carbonized at $700^{\circ}C$, $1000^{\circ}C$, and $1200^{\circ}C$. The enough stabilization introduced 16.4% of the oxygen approximately. The stacking height ($L_{c002}$) and interlayer spacing ($d_{002}$) of the as-spun fibers were 4.58 nm and $3.45{\AA}$ and the value became minimum and maximum at $700^{\circ}C$ respectively in the carbonization procedure. The tensile strength increased with an increase in the heat treatment temperature exhibiting highest value of 750 MPa at $1200^{\circ}C$ carbonization.

• Journal of Powder Materials
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• v.4 no.1
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• pp.9-17
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• 1997

The mullite-zirconia composites were prepared by the pressureless sintering with addition of 10~20 vol% ZrO$_2$(TZ3Y) in the fused mullite and sol-gel mullite matrix. The densification rate of sol-gel mullite was higher than that of fused mullite, and the addition of ZrO$_2$(TZ3Y) was effective on the densification of fused mullite. The enhancement of densification and anisotropic growth of mullite in ZrO$_2$added specimen can be explained by the solid solution effect of $Zr^{+4}$ ion in mullite. Both mechanical strength and fracture toughness of mullite-zirconia composite were enhanced compared to those of mullite. The enhancement of mechanical properties is attributed to the hinderance of grain growth and the combined toughening effects of tetra-mono phase transformation and crack deflection due to the residual stress between mullite/ZrO$_2$.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.15-21
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• 2009

The anisotropic mechanical properties were measured for the three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate. In tensile and flexural tests, axial and edge type specimens failed by pull-out of warp and fill yarns, respectively. In contrast, the thickness type specimens failed by adhesive failure process. Longitudinal cracking occurred in several of the edge type specimens during tensile test. That cracking caused pop-in in the stress-strain curve. Defects induced by improper coupon machining caused that cracking.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.114.2-114.2
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• 2011

We have developed a PDR code to reproduce the high rotational transitions of CO observed with Herschel-PACS. Part of these high-J CO line emission is produced by UV heated outflow walls around protostars. The local FUV radiation flux is calculated by using Monte Carlo method in (${\gamma}$, ${\alpha}$) grid taking anisotropic scattering into account. Kinetic temperature and Abundance of molecules were computed self-consistently. CO Line fluxes are calculated using RIG. We compare our PDR model with the results by Visser et al (2011) to show that the derived FUV radiation field strength can be affected by the grid resolution near the outflow wall and dust scattering.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.11a
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• pp.53-81
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• 2006

A COG(Chip on Glass) bonding process that is one of display packaging technology and bonds between driver IC chip and a glass panel using ACF(Anisotropic Conductive Film)has been investigated by using diode laser. This method is possible to raise cure temperature of ACF within one second and can reduce the total process time for COG bonding by a conventional method such as a hot plate. Also we can get good pressure mark on the surface of electrodes and higher bonding strength than that by convention method. Results show that laser COG bonding can give low pressure bonding and decrease a warpage of panel. We believe that it can be applied to fine pitch module.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.309-316
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• 1999

Laminated composite plates are very useful in various fields of engineering where high strength-to-weight and stiffness-to-weight ratios are required. Design optimization of composite structures has gained importance in recent years as the engineering applications of fiber reinforced materials have increased and weight savings has become an essential design objective. However, due to the anisotropic material properties of laminated composite structure it is very difficult to analyze and design. In this study, numerical optimization technique together with the finite element method is used to find the optimum design of FRP. Various combination of fiber orientation for the laminate layers are investigated and several local optimum solutions are found.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.39-41
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• 2004

The engineering properties of the geomaterial, an essential material in construction engineering, are significantly influenced by consolidation mode, which is called inherent anisotropy. Speically cohesive soils feature the anisotropy mainly due to their flate-like minerals and chemical interactions. In this research, an experimental study was conducted for the investigation of the anisoropy. Three isotropic and four anisotropic consolidated-undrained triaxial compression tests were performed for the cohesive specimens with various stress ratios of consolidation. The effects of the consolidation mode for cohesive soils were presented and investigated in stress-strain behavior, pore water pressure, and undrained shear strength of the test results.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.385-387
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• 1994

Optical interconnections are more attractive than electronic interconnections because of their higher speed, freedom from planar constraints, immunity to electromagnetic interference effects and higher interconnection capacity. Volume hologram is one of the best way to implement optical interconnections. Diffraction efficiency and crosstalk effect are very important things for ensuring independent interconnections. Recently, a general systematic method that can handle a large number of superposed volume gratings in anisotropic host material is presented. In this study for numerical analysis of diffraction, above method is programmed in general form near Bragg angle. Diffraction orders for variation of grating strength are determined by comparing with the coupled-mode method. The effects of parameter variation are considered. Parameters include vertical and azimuthal incident angle, wavelength and interaction length. Diffraction analyses are also performed for intra-mode and inter-mode diffractions.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.629-634
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• 2004

Based on plastic instability, analytical prediction of bursting failure on tube hydroforming processes under combined infernal pressure and independent axial feeding is carried out. Bursting is irrecoverable phenomenon due to local instability under excessive tensile stresses. In order to predict the bursting failure, three different classical necking criteria such as diffuse necking criterion for sheet and tube, local necking criterion for sheet are introduced. The incremental theory of plasticity for anisotropic material is adopted and then the hydroforming limit and bursting failure diagram with respect to axial feeding and hydraulic pressure are presented. In addition, the influences of the material properties such as anisotropy Parameter, strain hardening exponent and strength coefficient on bursting Pressure are investigated. As results of the above approach, the hydroforming limit in view of bursting failure is verified with experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.423-426
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• 2005

A new chip on glass(COG) technique by making use of a high power diode laser for LCD driver IC packaging of LCD has been developed. A laser joining technology of the connection of IC chip to glass panel has several advantages over conventional method such as hot plate joining: shorter process time, high reliability of joining, and better fur fine pitch joining. The reach time to cure temperature of ACF in laser joining is within 1 second. In this study, results show that the total process time of joining is reduced by halves than that of conventional method. The adhesion strength is mainly 100-250 N/cm. It is confirmed that the COG technology using high power diode laser joining can be applied to advanced LCDs with a fine pitch.