• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.839-846
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• 2007

Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• Archives of Metallurgy and Materials
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• v.65 no.3
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• pp.1069-1072
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• 2020

Mortar feedstock is extruded to form bead and it is selectively placed line by line in the material extrusion additive manufacturing. With respects to part building process healthiness, load-supporting ability of overlaid beads is emphasized as buildability. Buildability is primarily dependent on thixotropic properties of feedstock and vertical overlapping schedule. In the present study, water-to-binder (w/b) ratio was chosen as material aspect to assess buildability. Uneven bead shape evolution and premature failure were highlighted owing to low yield stress of high w/b ratio feedstock. Feedstock with optimum w/b ratio showed good buildability even at the interval time of 19 sec.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.21-25
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• 1996

• Proceedings of the KWS Conference
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• 1992.10a
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• pp.184-185
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• 1992

• Polymer(Korea)
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• v.37 no.5
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• pp.656-662
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• 2013

The flexible patterned cover film was made by a simple solution coating process using polymethyl methacrylate (PMMA) solution with glass beads. The effect of patterned cover film on the efficiency of solar cell has been investigated. It was found that the relative solar cell efficiency increased up to 3.4% with the incident light angle between $0-90^{\circ}$ by the sphere shape of glass bead coated on the film surface. This was understood that the loss of transmittance and scattering due to the light directional dependency on solar cell were minimized because the light entered glass beads normal to its surface regardless of incident light angle. The maximum relative solar cell efficiency was achieved when glass bead shape on the film is hemisphere and the relative efficiency increased with increasing the amount of glass bead on the film surface. However, too much glass beads on the film surface resulted in the lower relative solar cell efficiency due to the lowering of transmittance as well as the occurring of light interference.

• Journal of Welding and Joining
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• v.23 no.1
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• pp.48-54
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• 2005

Laser keyhole welding is investigated using a three-dimensional Gaussian heat source, and the heat source parameters such as the keyhole depth, welding efficiency and power density distribution factor are determined in a systematic way. For partial penetration, the keyhole depth is same as the penetration and is predicted using the experimental data. The welding efficiency is calculated using the ray-tracing method and the power density distribution factor is determined from the bead shape. Full penetration is classified into the transition, normal and excessive modes depending on the degree of keyhole opening. Thermal analysis of the bead-on-plate welds is conducted using the Gaussian heat source, and the calculated weld geometries show reasonably good agreements with the experimental results.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.216-218
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• 2000

In case of hardfaced wrapping roll, beadmark shape appear at wrapping roll surface due to irregular wear between weld bead. Irregular wear of this is caused by difference of hardness between weld bead. This study aims at investigating which matrix is good for removing of beadmark at wrapping roll surface. So, we make specimen with martensitic matrix and austenitic matrix. The hardfacing alloys were deposited 4 times on a SS41 steel plate using self-shielding flux cored arc welding method. Difference of hardness between weld bead of specimen with matrix of martensite was higher than specimen with matrix of austenite both as-welded and after heat treatment. Therefore, austenitic matrix is better than martensitic matrix for removing of beadmark of wrapping roll surface.

• Journal of Welding and Joining
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• v.18 no.6
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• pp.68-73
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• 2000

In case of overalyered wrapping roll, beadmark shape appear at wrapping roll surface due to irregular wear between weld bead. Irregular wear of this is caused by difference of hardness between weld bead. This study aims at investigating which matrix is good for removing of beadmark at wrapping roll surface. So, we make specimen with martensitic matrix and austenitic matrix. The overlayered alloys were deposited 4 times on a SS41 steel plate using self-shielding flux cored arc welding method. Difference of hardness between weld bead of specimen with matrix of martensite was higher than specimen with matrix of austenite both as-welded and after heat treatment. Therefore, austenitic matrix is between than martensitic matrix for removing of beadmark of wrapping roll surface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.700-705
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• 2009

In order to enhance the dynamic stiffness of automotive panel, effect of bead and curved surface was investigated. Modal test was performed for principle specimens which have various kinds of beads, holes and curved surfaces. Test was also performed for conventional dash panel assembly and rear floor panel assembly and curved shaped ones. Results showed that curved shape increased the natural frequency of automotive panel more effectively than the bead. Finite element analysis was also performed and yielded good match with the test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1167-1173
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• 2010

Forming of a silencer case was studied using a virtual tryout method. First, the appropriate blank shape was determined by cutting off the undeformed part of the rectangular blank. Then drawbeads were designed such that the formation of wrinkles on the shoulders and pipe connection can be prevented. Finally, the shape bead was designed such that fracture and formation of wrinkles around the pipe connection can be avoided. The prototype of the silencer case was manufactured in accordance with the conditions of the virtual tryout process. By comparing the formability of the prototype with the results of finite element analysis, it was found that the forming of the prototype agreed well with the results of analysis.