• Journal of the Korean Society of Clothing and Textiles
• /
• v.32 no.8
• /
• pp.1169-1178
• /
• 2008

In this study, a questionnaire was compiled by conducting interviews and preliminary surveys, and then handed out to a total of 270 welders working in shipyards to investigate their opinions on welding clothes. By which investigation, it was intended to understand their dissatisfactions and issues with conventional welding clothes and then propose of such welding clothes as may offer better fit and suitability. A total of twenty welding suits were collected to find the locations and degrees of wear and tear. Due to too large differences in the locations and degrees of wear and tear among the clothes, the evaluation was focused on ten suits out of the twenty suits collected. The researcher’s subjective judgment was used to select the nineteen most severely damaged parts, which were then photographed in a uniform distance and evaluated by a group of experts in terms of the degree of damage in order to locate most severely damaged parts and select adequate materials for those parts in designing an experimental suit. Based on two above evaluations, the experimental welding suit was produced in consideration of the design, materials and patterns. A lab evaluation and a site evaluation were conducted to compare the experimental suit and other conventional suits, a lab evaluation and a field evaluation were performed.

• Journal of Welding and Joining
• /
• v.28 no.3
• /
• pp.42-48
• /
• 2010

Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) were welded by a combination of a diode laser and a CNC machining center. Laser beam delivered through the transparent PC and was absorbed in an opaque ABS. Polymers were melted and joined by absorbed and conducted heat. Experiments were carried out by varying working distance from 44mm to 50mm for the focus spot diameter control, laser input power from 10W to 25W, and scanning speed from 100 to 400mm/min. The weld bead and cross-section were analyzed for weld quality, and tensile results were presented through the joint force measurement. With focus distance at 48mm, laser power with 20W, and welding speed at 300mm/min, experimental results showed the best welding quality which bead size was measured to be 3.75mm. The shear strength at the given condition was $22.8N/mm^2$. Considering tensile strength of ABS is $43N/mm^2$, shear strength was sufficient to hold two materials. A single process was possible in a CNC machining system, surface processing, hole machining and welding. As a result, the process cycle time was reduced to 25%. Compared to a typical process, specimens were fabricated in a single process, with high precision.

• Journal of Welding and Joining
• /
• v.12 no.3
• /
• pp.63-70
• /
• 1994

Laser processing workmen should select the working condition for laser cutting of new materials by the preparatory experiments for that material or from the past experiences in cutting of other similar materials. This paper proposes a criterion to determine how much a material is similar to other materials by using the Sugeno fuzzy integral. With the proposed criterion the laser processing workman can objectify the considered material for his decision. The expert system programmer can give the system a high flexibility by experimenting with some materials in a large range of similarity and can support the laser processing workman by offering the similarity between materials.

• Journal of Welding and Joining
• /
• v.28 no.5
• /
• pp.58-63
• /
• 2010

The purpose of this study is to develop improved boom structures with reliable fatigue strength of weldment and lower production cost. For that purpose, multibody dynamic analysis was performed to evaluate forces acting on arm & boom cylinders and joints of boom structure during operation of an excavator for three working postures, then stress analysis was made to investigate stress distribution around diaphragms at the bottom plate of boom structures which was known to be susceptible to fatigue failures of welded joints, and finally boom structure with optimum arrangement of diaphragms was proposed. This work basically consists of the following two parts: part 1 focuses on multibody dynamic analysis of excavators during operation and part 2 includes evaluations of fatigue strength of welded joints for modified boom structures.

• 한국금형공학회:학술대회논문집
• /
• 2008.06a
• /
• pp.31-34
• /
• 2008

The L-bending of inner-structure bonded sandwich sheet metal is examined to reduce springback and defects of bent parts. The specimen is composed of top and bottom layers and a middle layer with dimple type-inner-structure and each layer is bonded by resistance welding. This specimen with hollow type-inner-structure shows different bending characteristics from the conventional sandwich sheet metals with solid type-inner-structure. The experiments were conducted for two kinds of working conditions, that is, clearance and movement of first bent specimen for second bending. The deformed profile, bend angle and springback were investigated and compared and then the proper working conditions for L-bending of sandwich sheet metal were prosed.

• Journal of Welding and Joining
• /
• v.29 no.4
• /
• pp.61-66
• /
• 2011

The purpose of this study is to develop improved boom structures with reliable fatigue strength of weldment and lower production cost. For that purpose, multi-body dynamic analysis was performed to evaluate forces acting on arm & boom cylinders and joints of boom structure during operation of an excavator for three working postures, then stress analysis was made to investigate stress distribution around diaphragms at the bottom plate of boom structures which was known to be susceptible to fatigue failures of welded joints, and finally boom structures with optimum arrangement of diaphragms was proposed. This work mainly consists of the following two parts: part 1 focuses on multi-body dynamic analysis of excavators during operation and part 2 includes evaluations of fatigue strength of welded joints for modified boom structures.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2000.05a
• /
• pp.110-114
• /
• 2000

This paper shows the possibility of performing the friction stir welding and the development of optimizing tools for FSW with 2mm thick plate of aluminum alloys using milling machine. This research can be reported on achieving above 90% of the tensile strength in 1050 aluminum alloys friction stir welded in the room temperature. This welding process is very simple and does not require filler metal eliminates straightening of the workpiece. It is currently attracting interest from different industries working with aluminum alloys.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.54.2-54
• /
• 2002

Robots are widely used for welding automation in the shipbuilding industry. Because of the distinguishing mark of the shipbuilding, many robots conduct each other welding jobs at a point of time. The manager/operator stay in a place apart from working site for safety reason, but need to observe the progress of work and the status of robots. On this account, the monitoring system for welding robots has become essential. We developed a monitoring system by which, many people can monitor robot's status simultaneously at separated locations through the web. The monitoring system consists of Server and Client, where the server keep connection to robots and deliver client's request to robots and cli...

• Proceedings of the KIEE Conference
• /
• 1997.07b
• /
• pp.406-408
• /
• 1997

This paper presents the new method of a nondestructive spot welding state inspection system using neural networks. The learning process of neural networks makes the inspection system to adapt the variable welding parameters. The inspecting process is working with on-line real-time after off-line learning process. This neural network based inspection system shows reliable results through the field test for variations of applied voltages, currents, and contact area of the welding electrode.

• Laser Solutions
• /
• v.3 no.1
• /
• pp.12-20
• /
• 2000

The nuclear steam generators are subjected to corrosion environmental condition during operation that can result in stress corrosion in the tube wall. If any tube wall degradation is recognized, the tube must be repaired by plugging or sleeving. For the sleeving repair, Nd : YAG laser welded sleeving technology is one of the most promising when considering radioactive working conditions in the nuclear power plant. In this paper, the laser welding characteristics of steam generator tube and sleeve materials are investigated. The effects of average laser power, laser energy, welding speed, pulse duration and frequency are evaluated. Based on these results, Nd : YAG laser welded sleeving repair was applied to the degraded steam generator tubes in real environment.