• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.218-228
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• 2008

This paper describes on the real-time tracking of ship's dynamic behavior by AIS information in the coastal waters. The AIS data was received at a land station by using the antenna of AIS receiver mounted on the rooftop of the laboratory, Pukyong National University (PKNU), Busan, Korea, and stored as a NMEA format of serial output sentence of VDM(VHF Data-Link Message) and displayed on the ENC(Electronic Navigational Chart) of a PC-based ECDIS. In this study, the AIS receiver was mainly used to obtain the dynamic information that is necessary to evaluate and track the movement situation of training ship "KAYA" of PKNU in the coastal waters. The change of position with time for the ship turning under the rudder angle of port $30^{\circ}$ was correctly tracked with the turning circle of 940 m in diameter on the ENC of a PC-based ECDIS. Then, the dynamic information of the AIS system was updated every 6.29 seconds under the turning situation for the speed of 10.9 knots and every 21.65 seconds under the situation running at the speed of 11.05 knots on the straight line route of $155^{\circ}$, respectively. In case of AIS target tracking in the inshore zone behind large topographical obstructions, such as mountain and apartment buildings, the update rate of dynamic information was irregularly changed by the existence of land obstacles. However, the position tracking by AIS information under the situation existing no sea obstructions was achieved in real or near real-time and the instant presentation of course alternations for the ship was correctly monitored by using a PC-based ECDIS. From these results, we concluded that the PC-based ECDIS technology and methodology combined with the AIS information can be easily extended and applied to the surveillance and management for the fishing operation of fishing vessels in the coastal zone and in the EEZ fishing grounds.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.137-146
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• 2022

AIS(Automatic Identification System) is a device that automatically transmits and receives ship information and is mounted on the ship. AIS information of ships near the coast can be received on the ground, but when going out to sea more than 50 nautical miles, communication with the ground is cut off. To solve this problem, ship information can be transmitted to the ground through an AIS satellite equipped with an AIS receiver. There is no case of AIS satellite development in Korea yet, and many domestic shipping companies are using overseas AIS services. PNUSAT-1 is a 1U+ CubeSat, developed by Pusan National University, and it is equipped with an AIS receiver for monitoring of ships and transmitting ship information to the ground. Since the mission data of PNUSAT-1 is in text format, the data size is not large. In consideration of this, communication equipment, low-precision sensors, and actuators were selected. In this paper, system preliminary design of PNUSAT-1 was performed, requirements for mission performance, operation scenario and mode design, hardware and software selection, and preliminary design of each subsystem were performed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.1
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• pp.49-57
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• 2016

Recently, marine accidents such as the sinking accident Mongol freighter ship and the sinking accident of Sewol ferry in Jindo continuously happen. In order to decrease the number of these marine accidents, Korean ships are obliged to follow the AIS(Automatic Identification System) system. The AIS protocol includes all information for sailing ships. However, the standard AIS protocol does not provide any security function, In addition, it is possible to hijack the standard AIS protocol in case of using a satellite communication device called FUNcuve Dongle Pro+. Therefore, this paper analyzes weak points of the security in the standard AIS protocol. Furthermore, this paper ensures reliability by marking the MAC Address of sender and receiver for secure communication and suggests the protocol that can securely send data, using the VPN Tunnelling method. Therefore, the suggested AIS protocol provides the secure communication to the AIS protocol and protect the messages in the AIS protocol, which can serve safe voyages by decreasing the marine accidents.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.7
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• pp.273-281
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• 2003

This paper proposes a new time synchronization scheme for the Automatic Identification System(AIS). The proposed scheme utilizes a Temperature Compensated Crystal Oscillator(TCXO) as a local reference clock, and consists of a Digitally Controlled Oscillator(DCO), a divider, a phase comparator, and register blocks. Primary time reference is IPPS from GPS receiver that is synchronized to Universal Time Coordinated(UTC). And if GPS is unavailable, other station's signal is utilized as secondary time reference. The phase comparator measures time difference between the 1PPS and the generated transmit clock. The measured time difference is compensated by controlling the DCO and the transmit clock is synchronized to the Universal Time Coordinated(UTC). The synchronized transmit clock(9600Hz) is divided into the transmitting time slot(37.5Hz). The proposed scheme is tested in an experimental AIS transponder set. The experimental result shows that the proposed module satisfies the timing specification of the AIS technical standard, ITU-R M.1371-1.

• Journal of Space Technology and Applications
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• v.2 no.2
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• pp.121-136
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• 2022

Automatic Identification System used in ship communication is required for marine control way, including monitoring of vessel operation in coastal and exchanging of information for safety navigation between them. But, it uses a very high frequency band of approximately 160 MHz, and at the same time, due to the curvature of Earth, there is a limit to the communication distance. Several demonstrations were made successfully over satellite, but not much work has been done yet through cube-satellite which has low-orbit at 500 km altitude. Here, we demonstrate a reception test of AIS (automatic identification system) receiver for a cube-satellites using software-defined radio (SDR). We collected AIS data from ship at port of Busan, Korea, using R8202T2 SDR and established to transmit them using Adam-Pluto and Matlab Simulink. The process of weakening the signal strength to a satellite was constructed using attenuator. Through above process, we demonstrated whether AIS data was successfully received from the AIS payload.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.1
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• pp.50-55
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• 2010

The ship's heading information of hybrid GPS/EM compass were applied to the AIS of fishing vessel and examined the possibility of accuracy improvement. It is observed 453 each in AIS receiver of land among 3,982 each in AIS Rx/Tx transponder of the test ship at sea, and transmission interval according to the speed of ship is determined the 11.4% good transmitting data of the all information. In results, maximum compass error for the ship's heading of an EM compass was $19.1^{\circ}$. The variance of ship's heading owing to the speed of ship is surveyed. The COG (Course Over Ground) was changed extremely in $180^{\circ}W-179^{\circ}E$ range under 4.9knots, and in $24^{\circ}W-23^{\circ}E$ range over 4.9knots. Finally, using the ship's heading of EM compass and the COG from GPS for the autopilot system of a small fishing boat and the ship's heading information of AIS results in danger on the own ship's navigation safety and leads to make confusion both the others and VTS (Vessel Traffic Service) center. Therefore, the hybrid GPS/EM compass is identified as the best system for a small fishing boat and is allowed to offer continuously a ship's heading information with high accuracy and stability.

• 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 for Marine Environment & Energy
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• v.17 no.4
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• pp.297-305
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• 2014

In this study, we installed the Automatic Identification System (AIS) receiver on the Ieodo Ocean Research Station (IORS) from November 21 to 30, 2013 in order to monitor marine traffic and fishery activity in the jurisdictional sea area. The collected AIS raw data consist of static data report (MMSI, IMO NO., Call Sign, Ship Name, etc.) and position information report (position, speed, course, etc.), and the developed program was applied to classify ships according to ship flag and type information. The nationalities are released from the first three-digit numbers (MID) of MMSI, but in general most of small ships do not send an exact ship flag through Class B type AIS, a simplified and low-power equipment. From AIS data with flag information, ships under the flag of China had the highest frequency and the second was Korean flag, while in ship type cargo and fishing vessels were dominant in sequence. As for the ships without flag information, we compared the tracks with others in order to estimate ship flags. It can be said that fleets of ships with Chinese frequently appear sail together for fisheries over the waters, because the unknown ships followed a similar moving pattern with Chinese fishing vessels.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.339-343
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• 2022

In this study, a method for simplifying the structure of the VDES RF receiver, and the gain control method of the receiver to comply with the international standard in this structure was described. The input level of the wanted signal and unwanted signal to the receiver was defined, and when the two signals were input, the saturation state at the ADC was checked at the receiver output. As a result of the simulation by the circuit simulator, it was satisfied that the output power of the receiver was in the SFDR region of ADC with respect to the adjacent channel interference ratio, intermodulation, and blocking level. Through this study, it was found that the structure of th proposed RF receiver conforms to the international standard.

• Journal of Korean Neurosurgical Society
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• v.63 no.4
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• pp.470-476
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• 2020

Objective : The objective of this study was to develop a score to predict patients with acute ischemic stroke (AIS) who will not benefit from endovascular treatment (EVT) using computed tomographic angiography (CTA) parameters. Methods : The CTA-ABC score was developed from 3 scales previously described in the literature: the Alberta Stroke Program Early CT Score (0-5 points, 3; 6-10 points, 0), the clot burden score (0-3 points, 1; 4-10 points, 0), and the leptomeningeal Collateral score (0-1 points, 2; 2-3 points, 0). We evaluated the predictive value of CTA parameters associated with symptomatic intracranial hemorrhage (sICH) or malignant middle cerebral artery infarction (MMCAI) after EVT and developed the score using logistic regression coefficients. The score was then validated. Performance of the score was tested with an area under the receiver operating characteristic curve (AUC-ROC). Results : The derivation cohort consisted of 115 and the validation cohort consisted of 40 AIS patients. The AUC-ROC was 0.97 (95% confidence interval [CI], 0.94-0.99; p<0.001) in the derivation cohort. The proportions of patients with sICH and/or MMCAI in the derivation cohort were 96%, 73%, 6%, and 0% for scores of 6, 5, 1, and 0 points, respectively. In the validation group, the proportions were similar (90%, 100%, 0%, and 0%, respectively) with an AUC-ROC of 0.96 (95% CI, 0.90-1.00; p<0.001). Conclusion : Our CTA-ABC score reliably assessed risk for sICH and/or MMCAI in patients with AIS who underwent EVT. It can support clinical decision-making, especially when the need for EVT is uncertain.