• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.141-148
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• 1994

Both the neural network classifier utilizing multi-layer perceptron and the linear tree classifier composed of hierarchically structured linear discriminating functions can form arbitrarily complex decision boundaries in the feature space and have very similar decision making processes. In this paper, a new method for automatically choosing the number of neurons in the hidden layers and for initalzing the connection weights between the layres and its supporting theory are presented by mapping the sequential structure of the linear tree classifier to the parallel structure of the neural networks having one or two hidden layers. Experimental results on the real data obtained from the military ship images show that this method is effective, and that three exists no siginificant difference in the classification acuracy of both classifiers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.243-253
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• 2017

This study aims to compare Jeju Island, Shanghai, and Yokohama cruise ports and to investigate the relative strengths and weaknesses of Jeju Island. This study conducted comparative evaluation of 8 factors [airport, berth, expenses, distance, access to town, shopping facilities, source market (background market), and tourism] through a cruise network analysis. Comparative evaluation results find that Jeju Island, which secured 2 berths (berthing capacity) by completion of the civil-military complex port, has ascendancy over Shanghai cruise port and will have ascendancy over Yokohama cruise port once construction of the new airport is completed. Therefore, it will qualify as the best cruise port in Northeast Asia in the future. Results obtained from the cruise network analysis provide insights for administrative policy. Study limitations include only eight factors are used for evaluating the cruise-ship harbor area and surrounding hinterlands, and thus cannot sufficiently evaluate the complex conditions of the sites. In the future, it is necessary to reexamine the evaluation factors of the cruise ship harbor in detail. Furthermore, future research will need to consider the economic effects of the cruise ship industry, and its relevance to related industries as a possible fusion or hybrid industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4002-4014
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• 2015

ITU-R M.1842-1, as a well-known specification dedicated to maritime mobile applications, has standardized wireless transmission protocols according to the particular characteristics of a maritime communications scenario. A time division multiple access (TDMA) frame structure, along with modulation schemes to achieve a high data rate, has been described clearly in ITU-R M.1842-1. However, several specification items are still under "to be decided" status, which brings ambiguity to research works. In addition, the current version of ITU-R M.1842-1 is focused mainly on maritime transmissions in open-sea areas, where the cyclic prefix (CP) is set to zero and only 16-QAM is used in the multi-carrier (MC) system. System performance might be dramatically degraded in coastline areas due to the inter-symbol interference (ISI) caused by selective fading. This is because there is a higher probability that the signal will be reflected by obstacles in coastline areas. In this paper, we introduce the transmission resource block (TRB) dedicated to ITU-R M.1842-1 for a ship ad-hoc network (SANET), where the pilot pattern of TRB is based on the terrestrial trunked radio (TETRA). After that, we evaluated SANET performance under the maritime channel model in a coastline area. In order to avoid noise amplification and to overcome the ISI caused by selective fading, several strategies are suggested and compared in the channel estimation and equalization procedures, where the link-level simulation results finally validate our proposals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.327-333
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• 2013

In this paper, we propose a QoS information collection method at the information server in maritime networks with multi-network interfaces, and a route selection scheme based of the measured predictive QoS information comparing with parameters requested from a mobile node in a ship entering into a harbor from near-shore area. By changing network conditions and applying various application bandwidths, we check the operation of our proposed scheme and measure its performance of the original and proposed schemes in the viewpoints of the received packet traffic and end-to-end delays.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.254-262
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• 2013

This paper proposes FMT(Filtered Multi-Tone)-based digital radio implementation algorithms and the results obtained by various field tests especially in terms of transmitter characteristics. In this study, we predefined frame structure and protocols used for the CSTDMA(Carrier Sensing Time Division Multiple Access) scheme, designed digital filters and RF front end to fulfill the system characteristics such as the spectral mask and processing delays given by the Recommendation ITU-R M.1842-1. The proposed system supports exchange of data for e-Navigation with the usage of wider channel of 50-100kHz bandwidth, Turbo coding and FMT modulation. Furthermore, the common Ethernet protocol makes connection to local WLAN(Wireless Local Area Network) on board the ship for other data services.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.151-160
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• 1994

Recently, terrestrial photogrammetry has been applied effectively to data acquisition in GIS and to monitoring precise machinery for simulation test. Because 3-D coordinates of many object points can be quickly measured with constant accuracy and easy modeling by this method. In this study, the composition concerned with multi-camera system which simultaneously analyzes structure from multi-station using various cameras was developed. The errors of results were analyzed to investigate the accuracy of the system, error of unknown points and control points, convergent and strip adjustment for optimal network design also. As results of this study, the efficiency of multi-camera system developed here was proved through application to monitoring the entire area of the precise model ship. We could also acquire 3-dimensional coordinates with good accuracy by arranging pass points. Therefore, possibility of measurement of instantaneous deformation as well as precision analysis of structures can be suggested.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.33-43
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• 2021

A60 class bulkhead penetration piece is a fire resistance system installed on a bulkhead compartment to protect lives and to prevent flame diffusion in a fire accident on a ship and offshore plant. This study focuses on the approximate optimization of the fire resistance design of the A60 class bulkhead penetration piece using a multi-island genetic algorithm. Transient heat transfer analysis was performed to evaluate the fire resistance design of the A60 class bulkhead penetration piece. For approximate optimization, the bulkhead penetration piece length, diameter, material type, and insulation density were considered discrete design variables; moreover, temperature, cost, and productivity were considered constraint functions. The approximate optimum design problem based on the meta-model was formulated by determining the discrete design variables by minimizing the weight of the A60 class bulkhead penetration piece subject to the constraint functions. The meta-models used for the approximate optimization were the Kriging model, response surface method, and radial basis function-based neural network. The results from the approximate optimization were compared to the actual results of the analysis to determine approximate accuracy. We conclude that the radial basis function-based neural network among the meta-models used in the approximate optimization generates the most accurate optimum design results for the fire resistance design of the A60 class bulkhead penetration piece.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1298-1306
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• 2014

In this paper, we use the ECMA-392 standard, the first cognitive radio networks to meet the demand for IT services in the ship. And, we investigate about the conflicts of devices that support multi-hop network based on the ECMA-392. Therefore, we propose the resolution scheme of CRP reservation conflicts to solve this. The current CRP reservation approaches does not solve the CRP reservation conflicts of ECMA-392 between devices that move at a distance of three hops. Therefore, it is not possible to guarantee the QoS of real time services such as multimedia streaming. So, we provide a new CRP reservation scheme to avoid conflict through a new 2-hop CRP Availability IE and the change of CRP Control field. From the simulation results, we know that the proposed method of 3 hops CRP reservation conflicts resolution improves the throughput of device.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.483-488
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• 2015

This paper implements a long-term monitoring system (LMS) for ship's engine performance analysis (SEPA) based on the web, for the purpose of the communication speed and engine maintenance. This system is composed of a simulator, monitoring module with a multi channel A/D converter, monitoring computer, network attached storage (NAS), RS485 serial and wireless internet communication system. The existing products monitor the information transmitted from pressure sensors installed in the upper parts of each of engines in the local or web computer, but have a delay in the communication speed and errors in long-term monitoring due to the large volume of sampling pressure data. To improve these problems, the monitoring computer saves the sampling pressure data received from the pressure sensors in NAS, monitors the long-term sampling data generated by the sectional down sampling method on a local computer, and transmits them to the web for long-term monitoring. Because this method has one tenth of the original sampling data, it will use memory with small capacity, save communication cost, monitor the long-term sampling data for 30 days, and as a result, make a great contribution to engine maintenance.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.86-91
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• 2005

Regarding some of tire important works in tire shipyard, like tire production process, quality control, and material handling, there are many elements that disturb tire work-flaw. For example, there are mistakes in manufacturing, delay of production, and poor quality. These kinds of disturbances are from tire delay of communication time between tire production field and tire management. Therefore, it would be possible to strengthen tire competitiveness of shipbuilding industries by applying tire information technology based on Wireless Local Area Network (Wireless LAN), in order to establish tire multi-possession of real time production information in limited large shipbuilding yard. In this study, tire construction concept of tire information system, based on Wireless LAN, is proposed to build communication infrastructures in shipyards. The various information regarding shipbuilding inspection, process management, and material flaw are analyzed and constructed to databases in tire middle ware system, as tire platform for using Personal Display Agent (PDA). At last, tire middle ware system, which delivers tire information, is developed by tire C$\sharp$ and Microsoft.net; also, tire PDA application system is structured in WinCE O/S, and is tested and evaluated under tire server linked condition.