• Journal of Welding and Joining
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• v.30 no.5
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• pp.51-56
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• 2012

The purpose of this study is to evaluate the distortion and the residual stress of GTA tubular welds between tube and head. In order to do it, the heat input model for GTA welding process was first developed by experiment and FE analyses. The welding distortion and the residual stress distribution of the tubular welds according to welding pass and various restraint degrees were evaluated by using FEA with the heat input model. From FEA results, it was found that the residual stress and the radial distortion at the weld toe of tube part decrease with a decrease in the number of welding pass. However, the maximum residual stresses in each direction of tubular welds are almost constant regardless of the external restraint degree. It was mainly due to the high internal restraint of the welds.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.35-44
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• 2009

The purpose of this paper is to describe experimental results about the T-joint welding of the high power continuous wave (CW) fiber laser for SAPH steel plate for seat frame of car. The seat rail is a part of seat frame of cars. The assembling method is mostly fix up using a bolt and nut. But this assembling method has many demerits in productivity such as increasing work process and material cost. This paper presents an experimental study about Laser T-Joint weldability of seat rail. Laser welding has many advantages in lightness and saving material costs of seat frame. The laser beam was moved along the work pieces by six axis robot with process optical fiber. The laser beam is focused with a welding head within incident angle $15{\sim}45^{\circ}$ for the purpose of the T-joint welding through two side full penetration. The range of the root gap size is less than ${\leq}0.4mm$. Optical microscopy SEM were performed to observe the micro structures and determine the structures of welded zone.

• Steel and Composite Structures
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• v.19 no.6
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• pp.1381-1402
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• 2015

The application of composite steel-concrete slabs with profiled steel sheeting has increased, due to the various advantages in relation to reinforced concrete slabs such as, the reduced thickness, the reduced amount of lost formwork needed, as well as the speed of execution. The loss of longitudinal shear resistance is, generally, the governing design mode for simply supported spans of common lengths. For common distributed loadings, the composite behaviour is influenced by the partial shear connection between the concrete and the steel sheeting. The present research work is intended to contribute to improving the ultimate limit state behaviour of composite slabs using end anchorage. Eurocode 4, Part 1.1 (EN 1994-1-1) provides an analytical methodology for predicting the increase of longitudinal resistance, achieved by using shear studs welded through the steel sheeting as the end anchorage mechanism. The code does not supply an analytical methodology for other kinds of end anchorage so, additional tests or studies are needed to prove the effectiveness of these types of anchorage. The influence of end anchorage mechanisms provided by transverse rebars at the ends of simply supported composite slabs is analysed in this paper. Two experimental programmes were carried out, the first to determine the resistance provided by the new end anchorage mechanism and the second to analyse its influence on the behaviour of simply supported composite slabs.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.71-79
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• 2008

The concrete track is being used at the Phase II of the Kyeongbu High Speed Railway and New Constructed Honam High Speed Railway. When it makes a decision of bridge type, It has to consider about longitudinal forces of Continuous Welded Rail, Displacement at the end of bridges, Up-lift forces for fastener on the track. If it is installed turnout on the bridge, There is likelihood of the deck twist by applying the each difference longitudinal forces at the 4 each rails and the buckling by concentration of rail stress at the turnout. Moreover, If it is installed turnout on the continuous bridge and REJ(Rail Expansion Joint) on the main track or turnout track. It is hard to keep a safety for rail because of coming to twist or folding at the expansion of deck on the turnout track. Therefore when it is a design of bridge with turnout. It need to take bridge type to minimize an additional axial force and a displacement at the turnout. This paper makes a study of the composite steel arch bridge that is able to resolve criteria requirements of safety for track with turnout and suggest a helpful design method for bridge considering track with turnout by being based on design and construction method of Eonyang Bridge at the north part of Ulsan Station in Phase II of the Kyeongbu High Speed Railway.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.969-972
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• 2003

The overall aim of this paper is to determine coupling loss factor of welding point between shell and cylinder using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represent characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one way(nl- directional) power flow between multi-sub structures. Using these conditions, it is possible to find the equation of coupling loss factor expressed as above two loss factors. To check the effectiveness of above equation, this paper used two stage application. The first approach was application between simple cylinder and shell. The next was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding Point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.72-79
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• 2002

In this study, time-dependent distributions of temperature and stresses, in the box-column welded from ultra thick plates with center segregation, has been analyzed by the commercial finite element package SYSWELD+, for several types and angles of groove. The major points of investigation are the optimum type and angle of groove that minimize weld stress specially at the center segregation, as well as temperature distribution, residual stresses and changes in the mechanical properties. The results can be summarized as follows; 1) Generally the thermal cycle at the root of groove exhibits relatively rapid cooling pattern, however, most of the other part weldment have a slow cooling pattern in all groove types. 2) Most of the micro-structures of weldment are composed of ferrite and pearlite, meanwhile we could find martensite and bainite locally a the root of the groove. 3) Optimum groove type for high heat input welding of box-column corner is a double groove type, and the optimum angle for the groove is 30~$45^{\circ}$ that minimize deformation and weld stress at the center segregation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.2
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• pp.55-61
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• 2013

The horn is a key part of the ultrasonic welder. As the shape, mass and material of a horn have effects on the resonant frequency and the vibration mode in ultrasonic welding, a horn has to be designed and manufactured accurately. In this study, 40kHz band horn was designed and manufactured through the vibration mode and finite element analysis. A result of modal analysis showed that the natural frequency of the horn was 39,794Hz, and the frequency response by a harmonic response analysis was 39,800Hz - close to the intended frequency, 40kHz. In addition, weldability of the developed horn was estimated by welding of two Ni sheets and tensile-shear test of welded samples. It was shown the developed horn could be used in metal sheet welding.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.4
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• pp.525-531
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• 2007

The operating temperature has been increased to improve the efficiency of gas turbine. The most advanced Gas turbine is operated at above $1,500^{\circ}C$. Improvement in material and cooling method permit hot gas path component to run at increased temperature. But, the repair of blades which are developed with advanced manufacture technique is difficult to use normal welding. Most of gas turbine blades are made of precipitation harden nickel base superalloy, which is very hard to weld. Therefore, the employment of welding filler on blade is solid solution nickel base superalloy(Hastelloy X, Inconel 617). In this study, Tensile test in high temperature was conducted on welded GTD111DS with GTD111 to evaluate effect of variation of pre, post treatment. The result of this study showed that the specimen was treated with optimum pre and post treatment(preweld HT($1200^{\circ}C$), Post treatment($1100^{\circ}C$ HIP, $1200^{\circ}C$ + $1100^{\circ}C$ + $800^{\circ}C$ HT) is mush superior.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.55-64
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• 1998

Using blind hole drilling method the residual stresses and welding deflections are measured for the cylindrical shell with various heat inputs and cylinder diameters. As a result, it is verified that the axial and hoop residual stresses which are generated near the weld part of cylinders are increased, as the heat inputs and cylinder diameters are increased. And experimental results show good agreements with those of precedent researchers. In this paper, it is validated that dominant parameters, heat input Q and the dimension of cylinder h/D have some effects on the magnitude and distribution of axial and hoop residual stresses and welding deflections. The empirical equations of residual stresses and welding deflections are made by using multiple linear regression with experimental results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.277-286
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• 2001

Among the ULSAB methods for the lightweight automobile body, Tailor Welded Blank(TWB) is adopted and the design process is developed for the existing component. Topology optimization conducted to find the distribution of the variable thickness. The number of parts and the welding lines are determined from it. In the detail design, size optimization is carried out to find the optimum thickness of each part and then, the final parting lines are tuned by shape optimization. A commercial optimization software GENESIS is utilized for the optimization processes.