• Proceedings of the KWS Conference
• /
• 2007.11a
• /
• pp.177-180
• /
• 2007

The laser welding process was effective way to join the metals, because of the high productivity, the low distortion and the good weld quality. The fiber laser used the double-clad fiber architecture, the single element diode laser and the fully-spliced side pumping. It has the advantages in the views of the energy conversion efficiency, the beam quality, the robustness and the mobility. Recently, the thick material was welded with the high power laser in ship building or construction industry owing to the super bright fiber laser. In this study, we introduced the characteristics of high power fiber laser and its welding performance of thick gauge materials.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2007.09a
• /
• pp.22-25
• /
• 2007

Angular distortion in welding process is decided by the various variables. We can make the prediction of welding distortion in similar reality by the analysis of data through many specimen tests. However it is difficult that prediction of welding distortion applies to the ship building. We can establish that angular distortion varies directly as the specimen size. And, it makes clear distortion's difference between constraint and unconstraint, according to the change of a plate thickness.

• Journal of Welding and Joining
• /
• v.32 no.2
• /
• pp.4-8
• /
• 2014

In this research, GTA overlay welding system is developed for inside of straight pipes in various diameter. It can be applied to oil, ship building and plant industry, especially pipes connected to pressure vessels, for the purpose of cost reduction by cladding inside of pipes with corrosion and heat resistant alloys such as stainless steel or Inconel. Developed system consists of GTA power source, torch, wire feeding system, automatic arc length adjusting device, CCD camera and cooling unit. Two types of pipe inside overlay welding system are developed. One is for maximum 3m pipe length with 3 inch ~ 12 inch pipe outer diameter. Another type can be applied to maximum 12m pipe length with 7 ~ 24 inch OD. Developed system successfully produced inside cladded pipe and the results are shown through cross sectional images of the pipes.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.980-985
• /
• 2008

Since its invention at TWI in 1991, Friction Stir Welding (FSW) has become a major joining process in the aerospace, railway and ship building industries especially in the fabrication of aluminium alloys. In an attempt to optimize the friction stir welding process of Al alloys for extrusion Aluminium carbody of HEMU-400X (Extrusion Aluminum 6xxx series), effects of joining parameters such as tool rotating speed, plunging depth and dwelling time on the weld joints properties were evaluated. Experimental tests were carried out for butt joined Al plates. A wide range of joining conditions could be applied to join Al alloys for Extrusion Aluminum 6xxx series without defects in the weld zone except for certain welding conditions with an insufficient heat input. The microstructures of welds have dynamic-recrystallized grain similar to stir zone in FSW weld. For sound joints without defects, at the rotation speed of 700 rpm with different welding speeds, the tensile strengths of the Stir Zone(SZ) were almost the same, 80% of those of the base metal. (JIS Z 2201)

• Journal of the Korean Society of Systems Engineering
• /
• v.4 no.1
• /
• pp.11-18
• /
• 2008

As a government agency or the Government-donated Research Institute or industrial research institute is intended to develop a product or to construct a system such as a railway safety systems by research and development process, a life cycle model leading a product development or a research and development is essential to them to systematically and effectively progress it. In this paper, the refined life cycle model to effectively conduct the national railway safety project consists of the life cycle phases and their detail descriptions with reference to other life cycle model in the international standard and the other national guidance and other industrial domain such as ship-building, weapon system, and aerospace areas, the proposed life cycle model in the paper considerably reflects the characteristics of the traditional research and development project in railway safety domain. A guidance of a life cycle model which based on lots of the life cycle model in other domains proposes additionally.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.2
• /
• pp.137-143
• /
• 2022

Composite materials, being light-weight and of high mechanical strength, are increasingly used in various industries such as the aerospace, automobile, sporting-goods manufacturing, and ship-building industries. Recently, manufacturing of composite materials using 3D printers has increased. 3D-printed composite materials are made in free-form and adapted for end-use by adjusting the fiber content and orientation. However, research on the machining of 3D printed composite materials is limited. The aim of this study is to develop a machine learning method to select machining conditions for machining of 3D-printed composite materials. The composite material was composed of Onyx and carbon fibers and stacked sequentially. The experiments were performed using the following machining conditions: spindle speed, feed rate, depth of cut, and machining direction. Cutting forces of the different machining conditions were measured by milling the composite materials. PCA, a method of machine learning, was developed to select the machining conditions and will be used in subsequent experiments under various machining conditions.

• Journal of the Korea Safety Management & Science
• /
• v.25 no.1
• /
• pp.23-29
• /
• 2023

Among the Additive Manufacturing (AM) technologies, the Binder-Jetting printing technology is a method of spraying an adhesive on the surface of powder and laminate layer by layer. Recently, this technique has become a major issue in the production of large casting products such as ship-building, custom vehicles and so on. In this study, we performed research to make actual mold castings and increase mechanical property by using special sand and water-based binders. For use as a mold, it has a strength of more than 3MPa and permeability. Various experiments were carried out to obtain suitable them. The major process parameters were binder jetting volume, binder types, layer thickness and heat treatment condition. As a result of this study, the binder drop quantity was measured to be about 60 pico-liter, layer thickness was 100㎛ and the heat treatment condition was measured about 1,000℃ and compressive strength were measured to be more than 5MPa. The optimum condition of this experiment was established through actual casting of aluminum. The equipment used in this study was a Freeforms T400 model (SFS Co., Ltd.), and the printing area of 420 * 300 * 250mm and resolution of 600dpi can be realized.

• Korea Trade Review
• /
• v.47 no.6
• /
• pp.39-53
• /
• 2022

This study conducted a conformity review of Korean shipping industry policy and suggested that the Korean five-year shipping reconstruction policy has not violated the WTO (World Trade Organization) trade law agreement yet. In order to investigate the latest Korean shipping policy, domestic and foreign reports were reviewed, and after that, the WTO's published data and domestic and foreign journals were analyzed. Through this process, this study tried to review the conformity of trade laws by major Korean shipping policies. The shipping industry is a representative service industry, and subsidies for this are not subject to WTO-level regulation in principle. The purpose of Korean shipping industry policy is to support the shipping industry, a type of service industry, and even if the ship-building and manufacturing industries (shipper) indirectly spread benefits in the process, this is unintentional or private-level support. That is, this study concluded that It is understood that Korea's five-year shipping reconstruction policy does not violate the WTO trade law agreement.

• Journal of Navigation and Port Research
• /
• v.43 no.1
• /
• pp.72-78
• /
• 2019

The second-hand ship market provides immediate access to the freight market for shipping investors. When introducing second-hand vessels, the precise estimate of the price is crucial to the decision-making process because it directly affects the burden of capital cost to investors in the future. Previous studies on the second-hand market have mainly focused on the market efficiency. The number of papers on the estimation of second-hand vessel values is very limited. This study proposes an artificial neural network model that has not been attempted in previous studies. Six factors, freight, new-building price, orderbook, scrap price, age and vessel size, that affect the second-hand ship price were identified through literature review. The employed data is 366 real trading records of Panamax second-hand vessels reported to Clarkson between January 2016 and December 2018. Statistical filtering was carried out through correlation analysis and stepwise regression analysis, and three parameters, which are freight, age and size, were selected. Ten-fold cross validation was used to estimate the hyper-parameters of the artificial neural network model. The result of this study confirmed that the performance of the artificial neural network model is better than that of simple stepwise regression analysis. The application of the statistical verification process and artificial neural network model differentiates this paper from others. In addition, it is expected that a scientific model that satisfies both statistical rationality and accuracy of the results will make a contribution to real-life practices.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.7
• /
• pp.3184-3190
• /
• 2013

These days, the great part of design processes in the field of ship or offshore manufacturing are planed and implemented using the customized CAD system for each ship-building companies. It means that all information for design and production could be extracted and reused at the useful other area cost considerable time and efforts. The representative example is the estimation of welding length and material amount which is demanded during the construction of ship or offshore structures. The proper estimation of welding material to be used and the usage of them at the stage of schedule planning is mostly important to achieve the seamless process of production and expect the costing in advance. This study is related to the calculation of welding length and needed material amount at the stage of design complete utilizing the CAD system. The calculated amount are classified according to welding position, stage, block, bevel and welding type. Moreover it is possible to predict the working time for welding operation and could be used efficiently for the cost management using the results of this research.