• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.283-290
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• 2019

In global competition manufacturing companies have to produce modern, new constructions from advanced materials in order to increase competitiveness. The aim of my research was to develop a new composite cellular plate structure, which can be primarily used for structural elements of road, rail, water and air transport vehicles (e.g. vehicle bodies, ship floors). The new structure is novel and innovative, because all materials of the components of the newly developed structure are composites (laminated Carbon Fiber Reinforced Plastic (CFRP) deck plates with pultruded Glass Fiber Reinforced Plastic (GFRP) stiffeners), furthermore combines the characteristics of sandwich and cellular plate structures. The material of the structure is much more advantageous than traditional steel materials, due mainly to its low density, resulting in weight savings, causing lower fuel consumption and less environmental damage. In the study the optimal construction of a given geometry of a structural element of a road truck trailer body was defined by single- and multi-objective optimization (minimal cost and weight). During the single-objective optimization the Flexible Tolerance Optimization method, while during the multi-objective optimization the Particle Swarm Optimization method were used. Seven design constraints were considered: maximum deflection of the structure, buckling of the composite plates, buckling of the stiffeners, stress in the composite plates, stress in the stiffeners, eigenfrequency of the structure, size constraint for design variables. It was confirmed that the developed structure can be used principally as structural elements of transport vehicles and unit load devices (containers) and can be applied also in building construction.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.601-606
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• 2019

The lenticular Location Based System is related to a location information technology. The system enables users to inform their location in real time wherever in a room, a building, a ship, a basement. In this paper, we analyze limitations and problems of the existing indoor Positioning System and propose a method of user-oriented location service. The proposed method consists of a lenticular sticker, a database(DB) acquisition and analysis technology. The proposed system can be used as an infrastructure to implement various indoor location-based services. In addition to improve user centered positioning accuracy through the development of location-based systems using indoor lenticular systems, it can be used in a disaster situation.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.117-122
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• 2019

Pipes are widely used in various industries such as automobile, anti-vibration devices, factories and ship building. Chamfering is one of the most critical processes in pipe manufacturing which removes burrs of the pipes for better surface quality. In most cases, the defects of the chamfered surface are originated from the structural vibrations of the chamfering machine. In this study, the dynamic characteristics of a chamfering machine have been analyzed though the experiment and the computer simulation. And the effects of the design parameters affecting the stability of the machine have been investigated to stabilize the machine structure and further to reduce structural vibrations. The result shows that design alterations to stabilize the machine can suppress the defects of the machined surface as well as the vibrations during chamfering.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.4
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• pp.1360-1388
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• 2021

Shipbuilding and repairing enterprise has the characteristics of many hazards and accidents. Therefore, the safety management ability of shipbuilding and repairing MIS (management information system) must be effectively guaranteed. The verification on safety management is the necessary measure to ensure and improve the safety management ability of MIS. Safety verification can not only increase the safety of MIS, but also make early warning of potential risks in management to avoid the accidents. Based on the authoritative standards in the field of safety in shipbuilding and repairing enterprise, this paper applied modeling and verification method based on ontology to safety verification of MIS, extracted the concepts and associations from related safety standards to construct axiom set to support safety verification on MIS of shipbuilding and repairing enterprise. Then, this paper developed the corresponding safety ontology modeling and verification tool-SOMVT. By the application and comparison of two examples, this paper effectively verified the safety of MIS to prove the modeling method and the SOMVT can improve the safety of MIS in a much more effective and stable way to traditional manual analysis.

• Corrosion Science and Technology
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• v.19 no.6
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• pp.318-325
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• 2020

Generally, Al alloys of 5000 and 6000 series show excellent weldability, workability, and specific strength, and are widely used in ship building. A combined experiment via cavitation erosion and corrosion damage involving 6061-T6 Al alloy was performed using potentiodynamic polarization under cavitation erosion (hybrid experiments) with amplitude (cavitation strength). The corrosion current density was approximately 52-fold higher at 30 μm than under static conditions, suggesting that the amplitude greatly affected the damage. The degree of damage increased with increasing cavitation amplitude. After the hybrid experiment, the corrosion rate was compared according to the weight loss and damage depth, and the relationship between the two values was expressed as alpha value. The alpha (α) values at amplitudes of 5 μm, 10 μm and 30 μm were 5.11, 12.81 and 8.74, respectively, suggesting that the α value at 10 μm was greater than at 5 μm, and indicating local corrosion damage. However, the α value at 30 μm was smaller than that of 10 μm, which is attributed to higher damage via uniform corrosion than damage induced by local corrosion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.8
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• pp.72-78
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• 2022

Bending using high-frequency induction heating is used to bend pipes and sections, and is currently widely applied in industrial fields such as power generation facilities, ships, onshore plants, and offshore plants. The purpose of this study is to study the manufacturing process and design technology of high-frequency bending of pipe to make the best pipe design arrangement. Although various studies are being conducted in the field of high-frequency bending, more research is needed on high-frequency bending of pipes for ship building and offshore plants. The purpose of this study is to review the feasibility of production design using 3D model tool of S3D and AM(PDMS), and to review and improve bending thickness reduction, reduction rate, and roundness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.137-143
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• 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
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• v.25 no.1
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• pp.23-29
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• 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.

• Strategy21
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• s.30
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• pp.200-235
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• 2012

Over the past few years, due to the climate change of the earth, the Arctic's sea ice cover is undergoing a historic transformation - thinning, extent reduction in all seasons, and mitigation in the area of multi-year ice in the central Arctic Ocean. These changes allow for increases in maritime access throughout the Arctic Ocean and for potential longer seasons of navigation and possibly transarctic voyage in the summer. These changes also allow more exploration for oil, gas, and other minerals. The Arctic is now an archetype of the complex, multi-dimensional global problems of the twenty-first century. Military security, environmental security, and economic security interact. The potentially enormous economic stakes, sufficient to change the strategic balance among the states of the region, set off competitive pressures for national advantage. Korea, which is heavily dependent upon the sea lane in terms of transportation of its exports and imports, is very much interested in the Arctic sea routes. Korea believes that the Artic sea route, particularly the Northern Sea Route (NSR), could serve as a new useful sea lane, which will enable shorter times between East Asia and Europe, thus resulting in substantial cost saving for ship operators. In addition to shipping, Korea is interested in other Arctic-related maritime industries. Korea, as a leading shipbuilder in the global market, is interested in building ice breakers, drill ships, and other vessels which can contribute to safe operation in Arctic resource development and exploration. Korea, as one of the future stakeholders in Arctic maritime activities, should be ready to foster international cooperation in the region.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.132-137
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• 2015

A modular construction method includes factory-prefabricated room-sized volumetric units. Although low-rise buildings have been constructed worldwide using this method for more than 30 years, it is a relatively new technology in high-rise construction. There are three basic methods of constructing high-rise buildings using modular construction: the core method, the core-and-podium combination method, and the modular in-fill method. While the first two have been used in the USA and in several European countries, the third method, introduced in 2011 by an international cruise ship development firm, is a rather new approach for which there are few case histories. Therefore, its applicability and construction feasibility should be verified. As a pilot study to test the applicability of the modular in-fill method, a 12-story residential building was built in Korea. This paper describes a case study of the pilot project. The advantages and disadvantages of the method and its applicability in terms of cost effectiveness and construction schedule management were evaluated.