• Journal of Advanced Navigation Technology
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• v.13 no.2
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• pp.214-223
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• 2009

In this paper, we analysed and simulated the high speed mobile wireless channel for IEEE802.11p WAVE/DSRC standard draft. IEEE802.11p working group measured and suggested 6 channel model for WAVE/DSRC systems which is used for vehicle to vehicle or vehicle to infra communication. However, the models only provides numerical model, it did not provide Computer based software simulation model. So it can not be used directly for performance estimation of WAVE system. In this paper we suggested simulation technique of WAVE channel simulation which is developed S/W based WAVE channnel simulator. The simulation results for PSD, LCR, and AFD are also obtained, which can be used for performance estimation of IEEE802.11p based vehicular communication system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.667-669
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• 2021

Recently, RFID/USN technology has been applied in various fields such as logistics, environment, education, home network, disaster prevention, military, and medical care, but despite the remarkable development of RFID/USN technology, it is difficult to apply it to marine industry due to the characteristics of poor marine environment. Therefore, satellites are mainly used in the marine sector, and existing communication networks are used in the coast, so measures for forming a shelf-only short-range network in the ocean are being considered. In this paper, we consider the use of drones as mobile base stations of USN as a base station role using USN in existing PS-LTE and LTE networks.Since autonomous navigation vessels are aiming for the intelligent system, the number of crew and labor force should be reduced and the function of autonomous network formation in the form of more stable and intelligent ICT convergence technology should be strengthened.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.754-759
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• 2015

Nowadays, short distance communication systems with low power energy (LPE) are developed for identification and monitoring of site identification of vessel crews and passengers (SIVCP). LPE communication modules, such as Bluetooth low energy (BLE) and Zigbee, are used for short distance communications with LPE. These modules enable 1:N communications and their popularity is growing since the modules can be mounted on movable objects, such as mobile devices and human body. When these modules are used, the important factor that affects their operation time and design are the capacity and size of battery. Therefore, they must be made as small as possible, and the battery should be selected to be slightly smaller than the module. In this study, we calculate the theoretical life of batteries used in SIVCP BLE modules using data sheet and discharge characteristic graph under the condition of a 1/250 transmission-ratio (TR). We thus calculate experimental life by measuring transmission current for the same TR, and low speed mode current for a 1/5000 TR and measure long-term experimental life using 1/25 TR for days. Through these experiments, we verify experimental methods for the prediction and extension of battery life that would enable us to select appropriate sizes of batteries based on vessel usage and passenger types. The selections of the module TR and battery size are important factors affecting the cost reduction of module design, the battery maintenance, and passenger convenience.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.69-85
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• 2019

BeiDou navigation satellite system (BDS) is one of the four main types of global navigation satellite systems. The current system has been widely used by the military and by the aerospace, transportation, and marine fields, among others. However, challenges still remain in the BeiDou system, which requires rapid responses for delay-sensitive devices. A differential positioning algorithm called the data center-based differential positioning (DCDP) method is widely used to avoid the influence of errors. In this method, the positioning information of multiple base stations is uploaded to the data center, and the positioning errors are calculated uniformly by the data center based on the minimum variance or a weighted average algorithm. However, the DCDP method has high delay and overload risk. To solve these problems, this paper introduces edge computing to relieve pressure on the data center. Instead of transmitting the positioning information to the data center, a novel method called edge computing-based differential positioning (ECDP) chooses the nearest reference station to perform edge computing and transmits the difference value to the mobile receiver directly. Simulation results and experiments demonstrate that the performance of the ECDP outperforms that of the DCDP method. The delay of the ECDP method is about 500ms less than that of the DCDP method. Moreover, in the range of allowable burst error, the median of the positioning accuracy of the ECDP method is 0.7923m while that of the DCDP method is 0.8028m.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1098-1104
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• 2011

Data communications networks at sea can be modelled by multi-layered networks with traditional carriers (RF, satellites), and BWA (wireless LAN, WiBro, LTE), which partially makes it possible the high speed communication services (WWW, VoIP) at sea. In this paper, a novel routing scheme (CPR) is proposed which selects an optimal carrier for each hop in routes based on carrier preferences (CP). The carrier preferences are measured proactively depending on the feasibility of transmission characteristics (transmission rate, cost, and latency time) of the carriers for each application. Performance was compared with that of the OMH-MW (Optimal Medium per Hop based on Max-Win) routing scheme.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.850-856
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• 2012

Bilateration using two fixed nodes has been used in the field of the real time indoor location system in the narrow space such as building or ship passage. However, as the distance between the fixed nodes increases or any obstructions exist in their zone, it is difficult to detect the location of mobile node(user) due to the degradation of its reception ratio. In order to compensate for these problems, this paper presents, based on IEEE 802.15.4a chirp signal, a new real time indoor location system using stride measurement algorithm which can calculate the location through sensors attached to user. The proposed system consists of an ultrasonic sensor to measure the leg length, a geomagnetic sensor to recognize the user's orientation, and an inertial sensor to obtain the angle between the legs. The experimental results are shown that the proposed system has twice or more accurate output compared with conventional indoor location method in the section which is partially out of communication reachability.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.775-784
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• 2008

It is not easy to access very high speed Internet services at sea due to some technical and economical problems. In order to realize the very high speed Internet services at sea like on land, new communication network models based on MANET should be adopted. In this paper, a new MANET model at sea is provided, which considered the ocean environments, and the characteristics and movement of vessels. On the basis of the fact that most vessels navigate on the predetermined courses, which are the shortest paths between source and destination ports in most cases, a type of location oriented routing protocol is proposed in this paper. The Hybrid Course-Based Routing Protocol(HCBR) makes use of the static information such as courses and positions of ports to proactively find the shortest paths not only among ports but also the cross points of courses. HCBR also makes use of the locational information of vessels obtained via GPS and AIS systems to reactively discover the shortest route by which data packets are delivered between them. We have simulated the comparison of the performance of HCBR with those of LAR scheme 1 and scheme2, the most typical protocols using geographical information. The simulation results show that HCBR guarantees the route discovery even without using any control packet. They also show that HCBR is more reliable(40%) and is able to obtain more optimal routes(10%) than LAR scheme1 and scheme2 protocols.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.217-225
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• 2024

Even after the introduction of Global Maritime Distress and Safety System (GMDSS), many maritime accidents occur. A method of transmitting a rescue signal when a person falls into the water from a ship is currently being researched and developed in various ways, but no products have been developed that use frequencies allocated for maritime mobile service. Accordingly, in this study, we designed and produced a man-over-board (MOB) device by applying Group B AMRD technologies, which were adopted through the latest revision of the International Telecommunication Union (ITU). In addition, a receiver and user interface were built to verify the performance of the transmitter, and we confirmed that it can be used in conjunction with existing electronic charts. This MOB device satisfies the general and technical requirements of Group B AMRD using AIS technology and uses integrated components for miniaturization for easy portability in a maritime environment. We expect that it will achieve excellent AIS communication and be essential in rapid response and safety in emergency scenarios.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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• pp.390-400
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• 2021

One of the problems with abalone farms is that they need to be checked frequently after feeding them or visited once or twice a day and that the amount of food intake constantly fluctuates due to changes in water temperature around the farm and typhoons. In addition, the condition of abalone is not constant as it is divided into places that eat well and do not eat well according to its location. In order to solve this problem, there is a method of measuring the amount of food intake by using a load cell that can measure even the smallest weight in an abalone farm. Through this study, we implemented a system capable of measuring the amount of abalone feed required for systematic management of abalone farms and real-time monitoring using mobile and client PCs.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.177-183
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• 2006

IMO and ITU-R have done an intensive study to develop performance standards and technical standards of maritime digital communication systems, respectively. In particular, each administration strives to develop new agenda items of adopting digital new technologies. IMO COMSAR submitted draft performance standard of LRIT to IMO MSC, so that IMO mandates carriage requirement of LRIT In addition to that, COMSAR is preparing performance standard of AIS-SART, and approved the utilization of mobile phones for SAR activities. On the other hand, a new agenda item concerning E-navigation strategy was submitted to MSC 81th meeting. These challenges toward enhanced maritime radio communication systems would make it change largely the concepts of traditional navigation We suggest future directions of maritime information communication systems, investigating the study results of IMO and ITU-R.