• Journal of Welding and Joining
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• v.30 no.4
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• pp.38-43
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• 2012

Using a fiber laser heat source, an oil pressure sensor was fabricated to measure the pressure in commercial vehicles. A stepping motor was used for the rotational and translational motion in the diaphragms and hardware joining. Laser welding process algorism including shielding gas control and vision system was integrated by using LabVIEW software for the high quality welding and in-line monitoring purpose. For the maximum flexibility in pressure transmission to the pressure sensor, thin sheet metal diaphragm, $25{\sim}50{\mu}m$(SUS-316L), was used and the diaphragms were optimally designed with FEM analysis. The welded samples were cross-sectioned the observation showed that the maximum depth ratio was more than seven times of diaphragms. The maximum welding speed was measured to be as high as 50in/mm by the developed automation mechanism. The fabricated prototypes were tested for the proof pressure, spring constant and sealing. The FEM results of spring constant measurement was as accurate as up to 80% of the design value and the sensor was safely operated up to the nominal pressure of 10bars.

• Journal of Welding and Joining
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• v.33 no.5
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• pp.31-34
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• 2015

Microstructure and tensile property in the weld heat-affected zone (HAZ) of austenitic Fe-Mn-Al-C low density steels were investigated through transmission electron microscopy analysis and tensile tests. The HAZ samples were prepared using Gleeble simulation with high heat input welding condition of 300 kJ/cm, and the HAZ peak temperature of $1200^{\circ}C$ was determined from differential scanning calorimetry (DSC) test. The strain- stress responses of base steels showed that the addition of V improved the tensile and yield strength by grain refinement and precipitation strengthening. Tensile strength and elongation decreased in the weld HAZ as compared to the base steel, due to grain growth, while V-added steel had a higher HAZ strength as compared than V-free steel.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.109-117
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• 1993

A carbon/epoxy composite drive shaft used for the power transmission of the automobiles with steel joints. Compared with the metallic drive shaft, the composite one has the weight saving of 50% with equivalent torsional strength and fatigue characteristics. In this study, the filament winding technique for the composite tube and composite/metal joining technique are estabilished. The performance test of the drive shaft is carried out. The optimal condition of the surface roughness of the steel adherend was $1.5{{\mu}m}$ to $2.5{{\mu}m}$, and the optimal condition of the bonding thickness was 0.15mm. Maximum torque and torsional stiffness of the composite drive shaft manufactured by filament winding process were found to be $210kg{\cdot}m$ and $18.5kg{\cdot}m/deg$, respectively.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.168-170
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• 2005

Nickel base brazes containing boron and silicon as melting point depressants are used extensively in the joining and repair of hot-section components in next generation nuclear reactor and aero-engine. Therefore, the present study has investigated the preliminary applicability of nickel based alloying nano powders. Nano Ni-based alloying powders synthesized by Pulsed Wire Evaporation (PWE) method. It's powder morphology and phase transformation temperature were analyzed by scanning electron microscopy, transmission electron microscopy, and differential scanning calorimeter(DSC). The powder particle size was approximately 10${\sim}$100nm and exhibits a quite even equiaxed shape. The results of DSC measurement show that both the nano Inconel 625 nano powder and Inconel 718 nano powder presents similar liquidus temperatures approximately $1373^{\circ}C$ and $1380^{\circ}C$ respectively.

• Journal of Welding and Joining
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• v.29 no.5
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• pp.90-94
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• 2011

Ag metallic particles from nano-scale to submicron-scale are combined with organic solvent to provide fine circuits and interconnection. Ink-jet printing with Ag nano particle inks demonstrated the potentials of the new printed electronics technology. The bonding at the interface between the Ag wiring layer and the various substrates is very important. In this study, the details of interfaces in Ag wiring are investigated primarily by microstructure observation. By adjusting the materials and sintering conditions, nicely formed interfaces between Ag wiring and Cu, Au or organic substrates are achieved. In contrast, transmission electron microscope (TEM) image clearly shows interface debonding between Ag wiring and Sn substrate. Sn oxides are formed on the surface of the Sn plating. The formation of these is a root cause of the interface debonding.

• Journal of Welding and Joining
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• v.20 no.1
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• pp.41-46
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• 2002

A new laser welding system far the appendage of bearing pads of PHWR nuclear fuel elements has been developed. This system consists of laser oscillator, a optical fiber transmission, a monitoring device and a welding controller. The basic welding experiments of the appendage of Zircaloy-4 bearing pads were carried out. The laser welded samples were investigated and made by using the optical fiber of GI $400\mu\textrm{m}$. As a result, the seam welding with the bead width of 1.0mm and the weld penetration of 0.3mm could be accomplished.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.146-147
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• 2006

In order to prevent the environmental pollution, the dryers are commonly used to treat sludge that one of sewages is polluting the quality of water. Rotary dryer is a good apparatus to treat them. The rotary dryer is the way that is to make substance transmission and heat using hot air between sludge particle and heated gas. In this paper, a numerical analysis was performed for the structural analysis of the 3-pass rotary dryer through the finite elemeny method and an experiment was done for the structural stability. And reasonable relation was found between analysis and experiment.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.257-259
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• 2007

For this study, SM45C steel rods using generally for power transmission shafts and machine components was selected and welded by Butt-GMAW method. and then it was studied about estimation of fatigue strength and the region of infinite life. From this result, it is demanded that the stress for safety design of machine components using SM45C butt-welded steel rods must be selected in the region of the lowest infinite life of heat affected zone.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.384-386
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• 2005

Initial oxide layer on the butt surface fragments during friction stir welding (FSW) and then often remains as a faint zigzag-line pattern on the cross section. When remnant of the oxide layer often adversely affects the mechanical properties in the weld, it is called as 'kissing-bond'. The present study systematically examines effect of oxide array on bend property in the root of friction stir (FS) welded Al alloy 1050 by transmission electron microscopy (TEM), and then clarifies identity of the kissing-bond.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.433-435
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• 2003

As the nation's standard of living rises lately, the common interest in the environmental issue is raised and the environmental design of a transmission line is needed. When the environmental design is needed, KEPCO used a steel pole instead of a rectangular tower. A steel pole has many advantages such as simplification of a tower and less damage to the forest according to less demand of site. But the weak withstand weight of a mono type steel pole is a problem. This paper introduces an H type steel pole which improves its withstand weight, reduces a diameter of a pole from 2.6m to 1.3m and decreases joining points according to the increase of unit length of a pole from 6m to 9m.