• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.10a
• /
• pp.33-37
• /
• 2000

Milling fixture is one kind of machining device according to the industrial demands for multi manufacturing products on the growing at alarming rate. In the field of design and making for machine tool working, welding, assembling with fixture for mass production is a specific division. In order to prevent the production defects, occurring, the optimum design of product, fixture putting in the field is very significant manufacturing method. They require analysis of many kinds of important factors, theory and practice of machine tool operating process and its situations, fixture and its structure, machining condition for tool making tool materials, heat treatment of fixture components, know-how and so on. In this study we designed and constructed a milling fixture of mass production and performed tryout under the AUTO CAD, database, I-DEAS and WINDOW environment. Especially part 1 of this study is reveals with the analysis of part drawing, fixture planning, fixture design etc.

• Proceedings of the KWS Conference
• /
• 2005.06a
• /
• pp.19-21
• /
• 2005

The ball shea. tests for ball grid array (BGA) and flip chip packages were carried out with different displacement rates to find out the optimum condition of the displacement rate for this test. The BGA packages consisted of two different kinds of solder balls (eutectic Sn-37wt.%Pb and Sn-3.5wt.%Ag) and electroplated Au/Ni/Cu substrate, whereas the flip chip package consisted of electroplated Sn-37Pb solder and Cu UBM. The packages were reflowed up to 10 times, or aged at 443 K up to 21 days. The variation of the displacement rate resulted in the variations of the shear properties such as shear force, displacement rate at break, fracture mode and strain rate sensitivity. The increase in the displacement rate led to the increase of the shear force and brittleness of solder joints.

• Proceedings of the KWS Conference
• /
• 2005.06a
• /
• pp.291-293
• /
• 2005

The purpose of this study is to evaluate the effects of line heating variables for forming the curved plate on the behavior of distortion using FEA and experiment. The optimum mixed ratio and standoff for flame heating was established under the heating conditions given in this study. With the heating condition, the predictive equation of angular distortion and transverse shrinkage was established using FEA and verified by comparing the predicted results and experimental results.

• Laser Solutions
• /
• v.7 no.2
• /
• pp.19-26
• /
• 2004

The effect of shield gas on the weldability, mechanical properties and formability of CO2 laser weld joint in 600MPa grade high strength steel was investigated. Bead on plate welds were made under various welding speed and shield gas. Tensile test was carried out under the load of perpendicular and parallel direction to the weld line, Formability of the joint was evaluated by Erichsen test. As the welding speed increases, the porosity fraction decreases. The porosity fraction in the joint used Ar-$50\%He$ mixed gas as a shield gas was lower than that of the joint used Ar gas. Hardness at the weld metal of full penetrated joint was nearly equal to that of water quenched raw metal. In a tensile test under a perpendicular load to the weld axis, strength and elongation of joint produced by optimum condition were nearly equal to those of base metal. However, the strength of joint in a tensile test under a parallel load to weld axis was higher than that of raw metal, but the elongation of joint was lower than that of raw metal. Elongation and formability were further increased by the method of using Ar+He mixed gas as a shield gas as compared with Ar gas. Formabilities of joints were recorded ranging from $58\%\;to\;70\%$ of that of base metal with different shield gases.

• Journal of Welding and Joining
• /
• v.24 no.2
• /
• pp.64-70
• /
• 2006

The 3-dimensional (3D) chip stacking technology is a leading technology to realize a high density and high performance system in package (SiP). There are several kinds of methods for chip stacking, but the stacking and interconnection through Cu filled through-hole via is considered to be one of the most advanced stacking technologies. Therefore, we studied the optimum process of through-hole via formation and Cu filling process for Si wafer stacking. Through-hole via was formed with DRIE (Deep Reactive ion Etching) and Cu filling was realized with the electroplating method. The optimized conditions for the via formation were RE coil power of 200 W, etch/passivation cycle time of 6.5 : 6 s and SF6 : C4F8 gas flow rate of 260 : 100 sccm. The reverse pulsed current of 1.5 A/dm2 was the most favorable condition for the Cu electroplating in the via. The Cu filled Si wafer was chemically and mechanically polished (CMP) for the following flip chip bumping technology.

• Journal of Welding and Joining
• /
• v.10 no.3
• /
• pp.63-72
• /
• 1992

The joining methods of ceramics to metals which can be expected to obtain high temperature strength are mainly classified into the solid-state diffusion bonding method and the active brazing method. Between these two, the solid-state diffusion bonding method is given attentions as substituting method for active brazing method due to being capable of obtaining higher bonding strength at high temperature and accurate bonding. In this paper, the solid-state diffusion bonding of $Al_{2}$O$_{3}$ ceramics to Ni-Cr-Mo alloy steel (SNCM21) using insert metal was carried out. The insert metal employed in this study was experimentally home-made, Ag-Cu-Ti alloy. Influence of several bonding parameters of $Al_{2}$O$_{3}$SNCM21 joint was quantitatively evaluated by bonding strength test, and microstructural analyses at the interlayer were performed by SEM/EDX. From above experiments, the optimum bonding condition of the solid-state diffusion bonding of $Al_{2}$O$_{3}$/SNCM21 using Ag-Cu-Ti insert metal was determined. Futhermore, high temperature strength and thermal-shock properties of $Al_{2}$O$_{3}$/SNCM21 joint were also examined. The results obtained are as follows. 1. The maximum bonding strength was obtained at the temperature of 95% melting point of insert metal. 2. The high temperature strength of $Al_{2}$O$_{3}$/SNCM21 joint appeared to bemaximum value at test temperature 500.deg.C and the bonding strength with increasingtemperature showed parabolic curve. 3. The strength of thermal-shocked specimens was far deteriorated than those of as-bonded specimens. Especially, water-quenched specimen after heated up to 600.deg. C was directly fractured in quenching.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.20 no.2
• /
• pp.1-20
• /
• 1983

In this paper design criteria for semi-submersibles, effective at the stage of basic design, are reviewed first generally. Thereafter an extensive study is focussed on essential problematic areas such as design load, heaving motion, overall structural analysis and welding technique. The necessity for this kind of research is apparent in the light of the fact that ocean exploration and exploitation becomes extended to deeper ocean and that semi-submersibles are the most favorite unit for operation under this environment. In some sense principles in naval architecture are indeed applicable to the design of semi-submersible. However, because of the difference in geometry between ships and semi-submersibles, there are significant deviations in design method. A thorough discussion is made on particular behaviours of a semi-submersible in stability, wave load, motion characteristics and structural responses. Then some calculation-procedures and design guidelines are tentatively proposed. A numerical calculation for a semi-submersible Sedco 708 is exemplified for better understanding of the concept. The structure has 4 main and another 4 secondary stabilizing columns with catamaran-type lower hull. In this example design condition is supposed to be 28m wave height, 90 knots wind speed for survival condition and seastate 6 for operational condition in water of 100m depth. The numerical result implies that the actual design of this model can be assessed close to optimum. Further intensive research is strongly required in the subject fields of dynamic stability, rational evaluation of wave load statistical basis for fatigue life judgement.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.10
• /
• pp.1367-1375
• /
• 2010

In this study, optimization of the process parameters of the resistance spot welding of a sheet of aluminum-coated boron alloyed steel, 22MnB5, used in hot stamping has been performed by a Taguchi method to increase the strength of the weld joint. The process parameters selected were current, electrode force, and weld time. The heating temperature and heating time of 22MnB5 are considered to be noise factors. It was known that the variation in the thickness of the intermetallic compound layer between the aluminum-coated layer and the substrate, which influences on the formation of nugget, was generated due to the difference of diffusion reaction according to heating conditions. From the results of spot weld experiment, the optimum weld condition was determined to be when the current, electrode force, and weld time were 8kA, 4kN, and 18 cycles, respectively. The result of a test performed to verify the optimized weld condition showed that the tensile strength of the weld joint was over 32kN, which is considerably higher than the required strength, i.e., 23kN.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.4 no.3
• /
• pp.183-188
• /
• 2003

Non-molding and welding line happen by the assembly of gas at the connector terminal. There is not good phenomenon of burr by increasing the over injection pressure, the temperatures of die and resin to prevent from them. Therefore, the connector mold to apply the vacuum molding system is developed in this study. The vacuum pressure is controlled systematically with the optimum conditions in the important ingredients of injection molding that are the temperatures of melting resin and die and cooling condition. The badness in charging is cleared by making a vacuum to non-charging part of the deep bottom part of each cavity. And the vacuum system to reduce the cycle time is applied as the study envelopment of molding work. So, the good product and the productivity improvement can be obtained in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.568-571
• /
• 1997

The overall aim of this paper is to determine coupling loss factor 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 directional power flow between two sub structures. Using these conditions, it is possible to find the coupling loss factor equation. The comparison between theory of power transmission on conjunction and above equation, show a good agreement in simple beam structure. To check the effectiveness of above equation, it 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.