• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.343-351
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• 1988

Planar optical waveguides are fabricated on a Y-cut LiNbO3 single crystal substrate by Ti indiffusion method. From data measured by the bright M-line spectroscopy, refractive index profiles are reconstructed by WKB approximation method. Then, single strip, X-crossing strip, and Y-brinch strip optical waveguides are fabricated on X-cut LiNbO3 single crystal substrate, with waveguide patterns made by the laser beam direct writing method. And their near-field intensity profiles are observed after coupling the light to the waveguide edges.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1759-1763
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• 2014

In this paper, we were performed a structural analysis and durability analysis for an integral frame with an axle according to development of the electric locomotive traction motor. In terms of the structural stability, as a result of the analysis modeling with coupling conditions of beam element and an alternative element of three-dimensional, the maximum von-Mises stress of the locking screw mounting frame were similar as 50MPa and 51MPa. Also A comparison of the natural frequency and the exciting frequency while driving of the electric locomotive No. 8200, the natural frequency is 627.05Hz~856.9Hz while the exciting frequency is not more than most 30Hz or 553Hz, 1110Hz. Therefore, it is possible to avoid the resonance.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.72-72
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• 2002

Corrosion and tensile properties of zircaloy-4 cladding tube having a laser welding part in elevated temperature are studied to present the criterion of quality evaluation in nuclear reactor and find the scientific basis of SCC, with laser welding method using by coupling up cladding tube to end cap. In the result of tensile test(400℃), the fracture is not happened in the welding part but base metal and the result of corrosion test(400℃ 1500psi steam), corrosion rate of the molten zone and PMZ is a little higher than the other zone.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.796-801
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• 2002

Corrosion and tensile properties of zircaloy-4 cladding tube having a laser welding part in elevated temperature are studied to present the criterion of quality evaluation in nuclear reactor and find the scientific basis of SCC, with laser welding method using by coupling up cladding tube to end cap. In the result of tensile test($400^{\circ}C$), the fracture is not happened in the welding part but base metal and the result of corrosion test($400^{\circ}C$ 1500psi steam), corrosion rate of the molten zone and PMZ is a little higher than the other zone.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.306-306
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• 2011

Three dimensional(3D) topological insulators(TIs) of Bi binary alloys are characterized by a bulk energy gap with strong spin-orbit coupling and metallic surface states protected by time-reversal symmetry. It was reported that film forms of such materials were advantageous over bulk forms due to less defect density and better crystallinity. So far, the films have been prepared on several substrates including semiconductors and graphene. But, there were no studies on metal substrates. For electronic transport experiments and device applications, it is necessary to know epitaxial relation between TIs and metal electrodes. In this study, Atomically flat films of Bi2Se3 were grown on a Au(111) metal substrate by in-situ molecular beam epitaxy. Using home-built scanning tunneling microscope, we observed hexagonal atomic structures which corresponded to the outmost selenium atomic layer of Bi2Se3. Triangular-shaped defects known as Selenium vacancy were also found.

• Structural Engineering and Mechanics
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• v.42 no.5
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• pp.645-675
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• 2012

An effective design technique for symmetrical coupled shear walls is presented. Proposed formulation including assumptions and steps with mathematical formulation has been elaborated to make the design technique. An example has been considered to validate the technique with the DRAIN-3DX (1993) and SAP V 10.0.5 (2000) nonlinear programs. Parametric study has also been considered to find out the limitations along with remedial action of this technique. On the other hand, nonlinear static analysis is considered to determine the response reduction factor of coupled shear walls. Finally, it has been concluded in this paper that the proposed design technique can be considered to design the coupled shear walls under seismic motion.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.560-565
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• 2015

We report efficient direct coupling of THz dipole antenna pulses onto air spaced two-wire transmission lines and Teflon covered two-wire lines. The air spaced two-wire lines show TEM mode propagation with very small group velocity dispersion (GVD) and relatively low attenuation. The Teflon covered two-wire lines showed comparatively much higher attenuation and GVD. However, the Teflon covered two-wire lines show a very good guiding property when the lines are curved. Although the lines are circled only 5.0 cm in diameter, there is no additional attenuation compared to straight the lines.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.121-126
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• 2007

In this paper the vibration system is consisted of a rotating cantilever pipe conveying fluid and a tip mass. The equation of motion is derived applying a modeling method that employs hybrid deformation variables. 'TI1e influences of the rotating angular velocity, mass ratio and the velocity of fluid flow on the stability of a cantilever pipe are studied by the numerical method. The effect of tip mass on the stability of a rotating cantilever pipe are also studied. The influences of a tip mass, the velocity of fluid the angular velocity of a cantilever pipe and the coupling of these factors on the stability of a cantilever pipe are analytically clarified.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.97-99
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• 2005

Laser arc hybrid process is actively researched as a new welding method since it has several advantages by the combination of laser beam and electric arc. By the coupling of two different heat sources, laser and arc mutually assist and influence. High power laser can make the deep keyhole and arc plasma can form the large bead shape. In this paper the effect of two different heat sources to weld bead are investigated and as a result of analysis, it is shown that the lower part of keyhole is heated by laser and the upper part of weld pool is dominantly heated by arc.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.373-392
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• 2015

In the present work, structural joints have been modeled as a pair of translational and rotational springs and frequency equation of the overall system has been developed using sub-structure synthesis. It is shown that using first few natural frequencies of the system, one can obtain a set of over-determined system of equations involving the unknown stiffness parameters. Method of multi-linear regression is then applied to obtain the best estimate of the unknown stiffness parameters. The estimation procedure has been developed first for a two parameter joint model and then for a three parameter model, in which cross coupling terms are also included. Two cases of structural connections have been considered, first with a cantilever beam with support flexibility and then a pair of beams connected through lap joint. The validity of the proposed method is demonstrated through numerical simulation and by experimentation.