• 한국초전도학회:학술대회논문집
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• v.10
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• pp.289-292
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• 2000

In order to evade the patent of Oak Ridge National Laboratory (RABiTS process) and search for more economical process, a new process for producing the biaxially textured Ni tape by electrodeposition has been investigated. Electrodeposition was performed in the modified Watts bath. The crystal orientations of electrodeposited Ni were analysed by X-ray pole figure, ${\phi}$-scan and ${\omega}$-scan. The electrodeposited Ni tape showed cube texture with good out-of plane(< 8${\circ}$) and in-plane alignment(< 20${\circ}$).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.38-43
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• 2010

By generating 2-directional vibration in a xy plane of workpiece table, a newly developed micro drilling using 2-directional vibration was carried out. The vibration was produced by applying sinusoidal voltages to the orthogonally arranged piezoelectric materials built in the workpiece excitation table. Through the micro-drilling experiments using poly-carbonate and brass material, it was found that micro drilling using 2-directional vibration in a workpiece table could be an efficient method to enhance the form accuracy of machined workpiece by suppressing burr formation at both entry and exit region. A higher form accuracy could be obtained by increasing stiffness of feeding mechanism, decrease of geometric tolerance of combining jig, and development of high performance excitation table which generates amplified vibration at higher frequency.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.50-58
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• 2000

A linear elastic fracture mechanics analysis of multiful subsurface cracks propagation in a half-space subjected to moving thermomechanical surface traction was peformed using the finite element method. The effect of frictional heat at the sliding surface on the crack growth behavior is analyzed in terms of the thermal load and peclet number. The crack propagation direction is predicted in light of the magnitudes of the maximum shear and tensile stress intensity factor ranges. When moving thermomechanical surface traction exists, subsurface horizontal cracks are propagation in-plane crack growth rate at the beginning but they are propagation out-of-plane crack growth rate by the frictional heat which is occurrence by the repeated sliding contact.

• Journal of Korea Foundry Society
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• v.5 no.4
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• pp.283-288
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• 1985

The melt of highly purified Zn was poured by top pouring process into the open green sand mold, that was made by using the 3-plane L-sections pattern. After skin was formed, the unsolified melt was poured out by rolling-over. The thicknesses of skin for each different of castings were investigated with one dimension. The results obtained and could be summerzed as follows: 1) While the 3-plant L-sections castings were solidifying in the mold, solidification blocks of different section modulus in the castings were formed, i.e. 1-dimension divergency block, 2-dimension heat divergency block, 3-dimension heat divergency block, 2-dimension heat convergency block, and 3-dimension heat convergency block. 2) When the chill plate was set up to the mold in order to change section modulus artificially, heat divergency blocks and heat convergency blocks according to the shape of chill plate were revealed.

• Tribology and Lubricants
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• v.18 no.3
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• pp.219-227
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• 2002

A linear elastic fracture mechanics analysis of double subsurface cracks propagation in a half-space subjected to moving thermomechanical surface traction was performed using the finite element method. The effect of frictional heat at the sliding surface on the crack growth behavior is analyzed in terms of the thermal load and peclet number. The crack propagation direction is predicted in light of the magnitudes of the maximum shear and tensile stress intensity factor ranges. When moving thermomechanical surface traction exists, subsurface horizontal cracks are propagation in-plane crack growth rate at the beginning but they are propagation out-of-plane crack growth rate by the frictional heat which is occurrence by the repeated sliding contact.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.241-244
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• 1997

This paper proposes Electronic Speckle Pattern Interferometry(ESPI) for the quantitative buckling analysis of square tube, which is unable to be measured with previous methods. The quantitative buckling analysis in elasticity is important part to study strain-stress analysis of thick-plated tube and fatigue analysis. However, it is unsolved problem with theory and previous experimental method. The merits of ESPI, Whole-filed measurement and high accurate 3D-displacement measurement make it possible to determinate the buckling analysis in elasticity quantitatively.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1999-2001
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• 2000

Impulse breakdown voltage characteristics of sulphur-hexafluoride/nitrogen ($SF_{6}-N_{2}$) mixtures were presented. The applied voltages were the positive and negative lightning impulse (1.2/44${\mu}s$) and oscillating impulse ($0.4{\mu}s$/2.08MHz) voltages. The predischarge current was observed to clarify the breakdown mechanism. The electrode system was consisted of plane to plane configuration with a needle-shaped protrusion whose length and diameter are 10mm and 1mm. The measurements were carried out at the gas pressure of mixtures up to 0.5MPa with nitrogen concentrations varying from 5 to 20%. The electrical breakdown in $SF_{6}-N_{2}$ mixtures develops with steplike pulses in leader mechanism. The minimum breakdown voltages for the negative lightning and oscillating impulse voltages were higher than those for the positive.

• Tunnel and Underground Space
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• v.8 no.1
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• pp.46-52
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• 1998

The author conducted new back analysis method using monitoring data to a landslide which occurred around portal. In this case, because the tunnel being located under the sliding plane of the landslide, calculated value from the ordinary back analysis in which considered only stress release by the tunnel excavation didn't fit the measured value. Then, in the new method, a body force as the movement of the landslide mass was added to the ordinary back analysis and good results were obtained. Furthermore, the author carried out stability analysis of the landslide with the data of the back analysis and examined the loosened area and decreasing og the sliding plane strength due to the tunnel excavation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.651-656
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• 2004

This paper presents the application of Differential Transformation to the bucking load and the vibration problem of the rectangular plate loaded by varying in-plane stress. Numerical calculations are carried out and compared with previously published results to validate the results of the resent method. The results obtained by this method agree well with those reported in the Devious works. The results obtained by the present method are presented for various non-uniform loads.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.848-857
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• 2021

This paper proposes an efficient approach based on a machine learning technique to predict the local stresses on mooring chain links. Three-link and multi-link finite element analyses were conducted for a target chain link of D107 with steel grade R4; 24,000 and 8000 analyses were performed, respectively. Two serial Artificial Neural Network (ANN) models based on a deep multi-layer perceptron technique were developed. The first ANN model corresponds to multi-link analyses, where the input neurons were the tension force and angle and the output neurons were the interlink angles. The second ANN model corresponds to the three-link analyses with the input neurons of the tension force, interlink angle, and the local stress positions, and the output neurons of the local stress. The predicted local stresses for the untrained cases were reliable compared to the numerical simulation results.