• Journal of Welding and Joining
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• v.8 no.1
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• pp.23-30
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• 1990

The robotic welding has been adapted positively in many welding shops forthe purpose of improving the welding efficiency and liberating operators from the severe working atmosphere. But for a large-size structure with thick plates like ship-building and every kind of plants manufacturing, the application of the arc welding robots is not established yet. The reason is assumed that the conventional arc welding robots are not adaptive for multi-pass welding of thick plates whose grooves are not so accurate. As one solution to this problem, a guidance system which uses the welding arc itself as a sensor is largely used. In this study the velocity controller which changes the tip to workpiece distance for regulating the weld proposed. The proportional and integral gain of velocity controller were determined by using the computer simulation of the control system, and the simulation results compared with the experimental ones. It was revealed that the developed control system using the arc sensor principle has a good capability of tracking the weld joint, although some more studies will be needed to refine the model of arc current.

• Journal of Welding and Joining
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• v.14 no.6
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• pp.58-67
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• 1996

The horizontal filet welding is prevalently used in heavy and ship building industries to join the parts. The phenomena occurring in the horizonal fillet welding process are very complex and highly non-linear, so that its analysis is relatively difficult. Furthermore, various kinds of weld defect such as undercut, overlap, porosity. excess weld metal and incomplete penetration can be induced due to improper welding conditions. Among these defects, undercut, overlap and excess weld metal appear frequently in horizontal filet welding. To achieve a satisfactory weld bead geometry without weld defects, it is necessary to study the effect of welding conditions in the weld bead geometry. For analyzing the weld bead geometry with and without weld defects in horizontal fillet welding, a mathematical model was proposed in conjunction with a two-dimensional heat flow analysis adopted for computing the melting tone in . base metal. The reliability of the proposed model was evaluated through experiments. which showed that the proposed model was very effective for predicting the weld bead shape with or without weld defects in horizontal fillet welding.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.1-5
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• 2009

Recent growth in global economic situation has led dramatic increase in new buildings of large containerships. These increased new building orders have brought keen concerns of developing and improving the quality of design and increasing the productivity of the vessel in order to satisfy the ship Owner's various requirements. For the increment of productivity and quality of containership, the plastic type bearing pad of cargo hatch cover has been investigated intensively for years with the supplier of cargo hatch cover. The result of investigation showed that there are numbers of advantages for the Owner and Builder over the existing bronze bearing pads which are better corrosion resistance long life time, low friction coefficient, easy maintenance, easy installation, better production lead time and low maintenance cost.

• Journal of Korea Multimedia Society
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• v.18 no.11
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• pp.1319-1331
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• 2015

In the Republic of Korea, there's been a culture called 'Hyo' since Koryo Dynasty and this word represents the meaning of paying utmost respects to one's own parents and ancestors whether they are alive or have passed. However, nowadays, most of people live away from their family gravesites so that they do not and cannot take care of them except on the special holidays. For this reason, people could not respond promptly to the incidents occurred at the sites as they receive notifications much later dates most of the time. Thus, in this paper, we propose a low-cost gravesite monitoring system which the users can immediately respond to the disastrous events after being informed of current situations through PLC without delay. For the performance evaluation, the lab and test bed experiments were performed on an actual ship using 200Mbps and 500Mbps products instead of performing an on-site experiment after the system has actually been constructed. The Mountain Region PLC was installed on the power lines and the result showed successful 36.14Mbps communication. Therefore, we expect that this study will contribute in time and cost reduction while constructing the internet infrastructures in mountain regions or building the Smart-graves, tumulus, and charnel houses.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.105-114
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• 2015

Heated glasses are widely used to prevent surface condensation and freezing in ship and building windows. This study proposes a heated glass temperature control system composed of power and control circuits to control the temperature of heated glasses. The proposed temperature control system adopts a digital controller instead of a conventional analog controller. Thus, the proposed system has better characteristics, such as precise setup and control of glass temperature, setup and control of output power, and control mode change between ON/OFF and phase controls. The system can also implement multi-functional control algorithms. The control characteristics are not dependent upon external disturbances, such as ambient temperature and electrical noises. Furthermore, the proposed temperature control system utilizes the power line communication (PLC) method to control the number of heated glasses without any extra communication lines. The system proposes a new communication protocol with strong immunity to electrical switching noises. A new sensorless algorithm is used to detect the temperature of the heated glass. This study presents the design guidelines in detail and its effectiveness are confirmed by implementing a 4-kw prototype temperature control system.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.4
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• pp.50-55
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• 2007

Stereolithography (SLA) is a technique using a laser beam to cure a photopolymer liquid resin with three-dimensional computer-aided design (CAD) data, The accuracy of the prototype, the build time, and the cured properties of the resins are controlled by the SLA process parameters such as the size of the laser beam, scan velocity, hatch spacing, and layer thickness, In particular, the size of the laser beam is the most important parameter in SLA, This study investigated the curing properties of photopolymers as a function of the laser beam size, The cure width and depth were measured either on a single cure line or at a single cure layer for various hatch spacings and laser beam sizes, The cure depth ranged from 0.23 to 0.34 mm and was directly proportional to the beam radius, whereas the cure width ranged from 0.42 to 1.07 mm and was inversely proportional to the beam radius, The resulting surface roughness ranged from 1.12 to $2.23{\mu}m$ for a ratio of hatch spacing to beam radius in the range 0.5-2.0 at a beam radius of 0.17 mm and a scan velocity of 125 mm/sec.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.51
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• pp.263-283
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• 2011

There are two typical international rules in issuing guarantee for obligations of party which is responsible to provide some duties such as services, construction, plants, loan repayment, etc. The two internationally recognized rules are currently ISP98 and URDG758. ISP98 was firstly introduced in 1998 for American banks to issue standby letter of credit domestic and overseas for the area where UCP does not cover. URDG was introduced first in 1991 in the name of URDG458 but it has not been widely used and therefore new URDG named URDG758 came out in 2010 to accommodate more standard guarantee practice. At the face of these two prevailing international rules, the users are sometimes confused which rule would be more suitable for their individual transaction. This led us to conduct a comparative analysis on these two rules. Our study suggests that URDG758 is more adequate for construction, ship-building and plants-supply obligations whilst ISP98 is for financial obligations. Also attentions are required when issues such as counter guarantee, governing rule, presentation period, document examination period and default statement exist. This is because ISP98 and URDG758 have different view points.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.58
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• pp.287-311
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• 2013

In this study, the scope of previous logistics security were focused only on port and ship. Because of it now extends to the overall (export and import) supply chain areas and in regards with supply security programs in the international level, it reviewed supply chain security programs categorized them into 'ships and port security system', 'container screening system', 'logistics chain authorization system' which are expanded to be adopted in the international level. The major features of those programs are summarized as in building risk management system, providing information ahead, selectivity test and benefits to AEO authorized companies in the customs administration level. The government and companies which are to ensure supply chain security and trade facilitation in order to cope actively with international customs administrative atmosphere need to do the followings : First, they need to build an intra-government integrated supply chain security and make efforts to conclude AEO MRA in order to increase trade competitiveness among major trading countries. Second, they need to build supply chain risk management system in order to enhance management performance through overseas market and company level strategy to obtain and maintain AEO authorization in the company level.

• Korean Journal of Computational Design and Engineering
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• v.16 no.3
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• pp.197-206
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• 2011

Shipbuilding is a complex industry which contains a lot of knowledge, technology, and utilities. Hence, the necessity of the PLM (Product Life-cycle Management) system which manages life-cycle information of marine product has been increased. So, many studies related to shipbuilding PLM have been preceded, and there are some cases to be built. To implement collaboration and concurrent engineering of ship designing and manufacturing, interoperability of product data in heterogeneous system is required. Also, sharing and reusing knowledge are important for innovation of business process and productivity of enterprises. Even though many studies related interoperability of product data are going on in varies domain, the application to shipbuilding is deficient. This paper proposes a methodology for management and interconnection of BOM data based on ontology in heterogeneous PLM system of shipbuilding. Using Prot$\'{e}$g$\'{e}$-OWL, we built simple domain ontology of shipbuilding industry, and then, we integrated product information of shipbuilding BOM which is represented with different ontologies. We verified possibility of integration of shipbuilding BOM in heterogeneous PLM, using ontology.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.129-134
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• 2002

This study is focused on the layout design with sizing for the main propulsion shafting with controllable pitch propeller system. For appropriate design and successful manufacturing of controllable pitch Propeller system, it is based on specifications to be required from the customer as well as the stresses calculation and analysis of main propulsion system for hollow shafting. And it must be performed according to the U.S military specifications MIL-STD-2189(SH) with drawing of NAVSHIPS 803-2145807, and also the stress analysis by applying safety factor. The results are as follows : 1. For the main propulsion system with controllable pitch propeller, it is designed the following items propeller diameter, hub diameter, dimensions of oil distribution or actuating unit based on shaft mounting type, diameters of propeller and intermediate shaft, dimension of split muff coupling, coupling flange thickness and of coupling bolt diameter. 2. As the results, we can get complete our own design ability for the main propulsion shafting with controllable pitch propeller system with critical data which are necessary to establish shafting arrangement from the ship building companies.