• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.367-375
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• 2023

This study developed a new distance metric for vessel trajectories, applicable to marine traffic control services in the Korean coastal waters. The proposed metric is designed through the weighted summation of the traditional Hausdorff distance, which measures the similarity between spatiotemporal data and incorporates the differences in the average Speed Over Ground (SOG) and the variance in Course Over Ground (COG) between two trajectories. To validate the effectiveness of this new metric, a comparative analysis was conducted using the actual Automatic Identification System (AIS) trajectory data, in conjunction with an agglomerative clustering algorithm. Data visualizations were used to confirm that the results of trajectory clustering, with the new metric, reflect geographical distances and the distribution of vessel behavioral characteristics more accurately, than conventional metrics such as the Hausdorff distance and Dynamic Time Warping distance. Quantitatively, based on the Davies-Bouldin index, the clustering results were found to be superior or comparable and demonstrated exceptional efficiency in computational distance calculation.

• Journal of Navigation and Port Research
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• v.32 no.1
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• pp.103-108
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• 2008

In the maritime universities, cadets of deck part should practice on board training using training ships of university or merchant vessels of company for 1 year according to STCW Convention. For training period, trainees are educated many education items as to positioning ability, chart work ability, vessel operation ability and cargo operation ability etc. Among many abilities, vessel avoiding ability which is demanded as a basic ability for deck officer can't be gained easily, because avoiding maneuver of ship controlled by cadets is not allowable regally and encounter situations occur randomly. This paper investigated CPA to the various encounter types with other vessels during the ocean going navigation of T.S Hannara. We analysis danger degree per each encounter type, and proposed a basic material of efficient training education about proper look-out and avoiding maneuver.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.165-172
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• 2015

The class of Dynamic Positioning System is divided in 3 classes depending on its redundancy and reliability according to IMO and classification society. There are 3 DP classes such as DP Class 1, 2 and 3 according to IMO MSC/Circ. 645. Higher DP class vessel has higher reliability, since redundancy concept is applied to the DP vessel depending on its DP class and can operate more safely. There are not enough information about DP class notation, which are needed when a company builds a new or buys second hand DP vessel or modifies DP classes, even the Korean shipyard is building a lot of DP vessels now. Also, the practical case of DP vessel modification, which had been done in Korea, to meet DP notation of IMO and classification society, will be helpful for DP vessel modification and sales industry development in Korea as a new business. As such this research identified what kind of requirements need to be taken into account to be from DP class 1 to DP class 2. The real DP class modification case is used to identify the requirements of DP class upgrade. Through the FMEA the redundancy concept on power system, thruster system and DP control system need to apply for DP class upgrade. The power system have to keep its DP function even if just a single fault happens on the generator or switchboard. Also, the PMS is required to monitor and control power system. Ship's Surge, Sway and Yaw movements can be controlled by the remaining thruster system after a single thruster fails. Lastly, multiple installation of PRS, sensors and DP control system are required to keep DP ability after a single fault on the DP control systems.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.217-225
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• 2014

The system that covers gathering, integrating, exchanging, presenting and analyzing of information within ships and shores for the safety and security in Marine Environment is known as e-Navigation Policy. Northern Europe has been conducting research and development. It came up into a concept that deals with ship's route information between vessels as well as vessels to shores which is better known as route exchange system. The research showed substantial advantages on navigational safety by exchanging the route information between vessels in vicinity and vessels to shores. Therefore, upon the adaptation of route exchange System as a major function in integrated navigational system, the existing procedures in VTS could be changed for betterment. In this study, it was verified the effectiveness of route exchange system by the adaptation of a recent collision accident occurred in Korean coast and suggested that route exchange system which would be carried out by the discretion of VTS center in VTS area. Finally, it proposed the new functions for outstanding services and procedures of integrating traffic organization services on coastal VTS for an effective route exchange system in Korean coastal area.

• Journal of Korea Port Economic Association
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• v.32 no.4
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• pp.57-71
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• 2016

The development of ocean industries is an existing and important problem for South Korea, which is mostly surrounded by sea and has a long coastline along three seas. It is necessary for researchers to make efforts to enhance its cost and time competitiveness, because many ocean-based activities have been carried out in harsh physical conditions when compared with land-based ones. One of these efforts to improve efficiency is to operate an Offshore Supply Base (OSB), which is a basic infrastructure required to develop ocean industries effectively. For this reason, the construction and operation of OSBs have become an issue in Korea. The relevant research is limited. Nevertheless, there are a few reports published by Korean research institution. They focus on promoting ocean industries and only mention the necessity of OSB as a promotion tool for the industries. This study on the other hand, addresses various issues on the construction of OSBs in Korea and suggests implications for them. To examine the conditions on the construction of OSBs in Korea, we conduct case studies of Houston and Singapore, the representative regions where a massive OSB has been constructed and operated. In addition, we use Analytic Hierarchy Process (AHP) to evaluate the relative priorities of the services provided by OSBs if constructed in Korea.

• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.343-349
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• 2006

In order to enhance the robustness against noisy environment, the previous GPS initial synchronization method of DGPS reference stations adopts not only the coherent integration method but also the non-coherent integration method. However the previous GPS initial synchronization method muses the non-coherent integration loss, which is a dominant factor among the signal acquisition losses in noisy environment. And the non-coherent integration loss increases with the strength of noise signal. In this paper, a novel GPS initial synchronization method is proposed for robust DGPS reference stations in noisy environment. This paper presents that the proposed GPS initial synchronization method suppresses the non-coherent acquisition loss. Furthermore, with regard to the mean acquisition time, it is shown that the number of the search cells of the proposed GPS initial synchronization method is much smaller than that of the previous GPS initial synchronization method Finally, through the simulation by the GPS simulator, it is seen that the GPS signal of nigh signal-to-noise ratio can be acquired under increased noise floor using the proposed GPS initial synchronization method.

• Journal of Navigation and Port Research
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• v.45 no.6
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• pp.276-283
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• 2021

The capital structure of the shipping business, which is characterized by its capital intensity and extreme market volatility, is closely related to long-term stability. Research in this area has been conducted mostly in the form of deriving the determinants of capital structure from company-wise financial ratios. This research, on the other hand, has a different approach to the topic. It identifies the relationship between actual cash profit and loss and other variables - i.e. actual vessel prices, interest rates and leverage ratio - by employing historical simulation. The result demonstrates that the P anamax cash profit shows 0 (break-even point) when the debt weight reaches 64.38% (debt ratio 180.74%) and the Cape, 73.04% (debt ratio 270.92%). Additionally, the ships of different types show a divided pattern for the pre- and post-'Super Boom'. It indicates that the business area and the market cycle should be considered when a leverage strategy is established. This research benefits shipping companies set a rational leverage strategy as well as delivers a reasonable guideline to government authorities for the development of a sound policy on shipping finance.

• Journal of Navigation and Port Research
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• v.45 no.1
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• pp.26-32
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• 2021

In ocean field, the spread of the Fourth Industrial Revolution based on information and communication technology requires high precision and stable PNT&D (Position, Navigation, Timing and Data). As the IMO (International Maritime Organization) and IALA (The International Association of Marine Aids to Navigation and Lighthouse Authorities) are requiring backup systems due to mitigate vulnerabilities and the increase of dependency on GNSS (Global Navigation Satellite System), Korea is conducting a research & development of R-Mode. An DGPS (Differentiate Global Positioning System) reference station that uses MF, an existing maritime infrastructure, and AIS (Automatic Identification System) base stations that use 34 integrity station and VHF will be utilized in this study to avoid redundant investment. Because there are radio shadow areas that display low signal levels in the west sea, the establishment of new R-Mode reference and integrity station will be intended to resolve problems regrading the radio shadow area. Because the frequency has a characteristic in that radio wave transmits well along the ground (water surface) in low frequency band, simulation and measurement were conducted therefore this paper to propose candidate sites for R-Mode reference and integrity station resulted through p wave's propagation characteristics analysis. Using this paper, R-Mode reference and integrity station can be established at appropriate locations to resolve radio shadow areas in other regions.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.200-201
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• 2023

Digital twin technology is used in various fields as a method of creating a virtual world to minimize the cost of solving problems in the real world, and is also actively used in the maritime field, such as large-scale systems such as ships and offshore plants. In this paper, we tried to build a digital twin of coastal waters using a ship-handling simulator. The digital twin of the coastal waters developed in this way can be used to safely manage Korea's coastal waters, where maritime traffic is complicated, by providing a actual maritime traffic data. It can be usefully used to develop and advance technologies related to maritime autonomous surface ships and intelligent maritime traffic information services in coastal waters. In addition, it can be used as a 3D-based monitoring equipment for areas where physical monitoring is difficult but real-time maritime traffic monitoring is necessary, and can provide functions to safely manage maritime traffic situations such as aerial views of ports/control areas, bridge views/blind sector views of ships in operation.

• Journal of Korea Port Economic Association
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• v.36 no.3
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• pp.55-74
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• 2020

With globalization and the development of information and communication technology, the supply chain is becoming more widespread and complex, which increases the occurrence and damage caused by supply chain risks. Supply chain risk management has a great impact on corporate performance through the analysis of risk factors and proactive and strategic approaches. This study aims to analyze the effects of supply chain risk factors on risk management strategies and corporate performance empirically. In the research model for empirical analysis, supply chain risk factors were classified into supply, demand, operation, network, and external environment, while the risk management strategies were divided into active and passive strategies, as well as financial and operational performance for corporate performance. The data obtained via the questionnaire were analyzed for the path of the structural equation model. As a result of the analysis, companies are actively pursuing risk management for internal risk factors, rather than external factors, in terms of internal and external risk factors, and it was found that these strategies have a significant effect on corporate performance. Therefore, in the future, companies should conduct risk management strategies more proactively and preemptively through a thorough analysis of various risk factors affecting business operations.