• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.523-529
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• 2021

This paper shows the design and fabrication of antenna embedded in marine buoy for marine IoT service, especially automatic identification system of fishing gears. Frequency band of proposed antenna has dual band of 433 MHz and 920 MHz considering marine IoT extension. Dual pattern monopole type for 920 MHz and meander type for 433 MHz are adopted in the proposed antenna. Voltage standing wave ratio is obtained 1.548 at 433 MHz and obtained 1.5 of mean value at 920 MHz band by measuring the fabricated antenna. The maximum antenna gain of 3.83 dBi is measured at 902 MHz among 920 MHz band, while antenna gain of 433 MHz is obtained 1.18 dBi. Although antenna gain of 433 MHz is low than 920 MHz band, this gain is larger than desired value of -5 dBi. And, it is confirmed that other measured values meet the performance criteria for archiving communication distance of 10 km between marine buoy and fishing ship in automatic identification system of fishing gears.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.888-896
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• 2023

When an aircraft is landing, it is expected that the aircraft will follow a specified approach procedure and then land at the airport. However, depending on the airport situation, neighbouring aircraft or the instructions of the air traffic controller, there can be a deviation from the specified approach. Detecting aircraft approach patterns is necessary for traffic flow and flight safety, and this paper suggests clustering techniques to identify aircraft patterns in the approach segment. The Gaussian Mixture Model (GMM), one of the machine learning techniques, is used to cluster the trajectories of aircraft, and ADS-B data from aircraft landing at the Gimhae airport in 2019 are used. The aircraft trajectories are clustered on the plane, and a total of 86 approach trajectory patterns are extracted using the centroid value of each cluster. Considering the correlation between the approach procedure pattern and overshoots, the distribution of overshoots is calculated.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.623-629
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• 2015

In the present study, a coplanar waveguide (CPW)-fed printed monopole antenna with an inverted n-shaped slot is newly proposed for dual band operations which cover bandwidths of CDMA (1.85~2.025 GHz) and WLAN (2.4~2.484 GHz) as well as implementation of omnidirectional radiation pattern. For enhancement of impedance bandwidth ($S11{\leq}10dB$) in 2.4 GHz WLAN frequency band, an inverted n-shaped slot instead of the previous n-shaped slot is etched on the printed radiating monopole. The proposed antenna is designed and fabricated on one side of FR4 substrate with dielectric constant of 4.4, thickness of 1.6 mm, and size of $50{\times}25mm^2$. It has been observed that the measured impedance bandwidths are 280 MHz (1.84~2.12 GHz) in frequency band of CDMA and 420 MHz (2.38~2.8 GHz) in WLAN frequency band respectively. It is noticeable that impedance bandwidth in 2.4 GHz frequency band of WLAN is enlarged to three times due to use of inverted L-shaped slot in comparison with impedance bandwidth 140 MHz (2.39~2.53 GHz) obtained by use of the previous n-shaped slot. In addition, good omnidirectional radiation patterns have been observed over the entire frequency band of interest.

• Journal of Global Scholars of Marketing Science
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• v.13
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• pp.135-158
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• 2004

On-line consumers have some visit behavior characteristics when they visit internet-shopping mall between visit-stage and purchase-stage. Therefore, information of on-line consumers have influenced on internet-shopping mall's profitabilities at site manager's perspectives. For examples, Are any on-line consumers continuous visiting under any situations? Or are any on-line consumers purchased on any specific internet-shopping mall? Expecially in this paper, researcher tried to understand visit behavioral characteristics of on-line consumers using two-stage mixture regression analysis. Throughout this process, it could be proposed method, which could be reinforced competitiveness of internet-shopping mall by segmental decision-making method. Additionally, it is expected that visit behavioral characteristics' information could be supplied strategic implications between visit-stage and purchase-stage Throughout empirical test it could be proved two-stage decision-making process, which decision-making process of on-line consumers would be processed visit-stage and purchase-stage. In this study, researcher proposed suitable response strategy after understanding visiting behavioral characteristics of on-line consumers. This paper has some academical contributions, which visit behavioral characteristics of on-line consumers could be grasped the meaning by site stickiness and navigation pattern.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.137-145
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• 2002

Water flow simulations for environmental problems often require local detailed analyses for better understanding and accurate prediction of the fate of pollutant in water bodies. This study deals with the development and application of a two-dimensional flow an dispersion model to the coastal water area to find out possible changes due to the wide port development plan. As far as the spatial discretization is concerned, the finite element method is attractive because of its flexibility and ability to naturally treat complex coastal geometries. The model uses finite element theory and the Galerkin weighted-residual approach as its basis. Developed model is applied to the Busan New harbor Construction site. Results from the model were compared with the measured water level and flows in four stations. The flow pattern by the model shows to be similar to the observed data away from the construction site where the flow is not affected. From the simulation results, it is concluded that the model may be useful for numerous other studies for planning and management purposes, especially flow and pollution dispersion in the coastal water bodies where the flow is so complicated.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.529-538
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• 2018

The port industry is an important national industry which significantly affects Korea's imports and exports which are centered on economic structure. For instance, the Port of Busan, which handles 75% of domestic container freight volume, is expected to become increasingly critical for container liner routes. For this reason, there have been continued efforts to expand freight service to attract international freight volume. This study analyzes the structural characteristics of the port network connected to the Port of Busan by analyzing the pattern of the container liner route from 2012 to 2016 by using social network analysis. According to the Port of Busan's liner route network, the port with the highest degree of centrality, closeness centrality, and betweenness centrality was found to be the Port of Singapore. The comparison of Busan's annual container handling rank by countries and the port center network analysis of Port of Busan rank was found to be different. As a result, it was established that China's East Port, which occupies a high percentage of the volume of cargo handled by Port of Busan, is not a hub port of Busan when viewed on the Busan's container terminal liner network. In addition, even if the number of Port of Busan container liner service increases, it is estimated that the vessels to be added to the fleet will be limited to small to medium sized, or that Busan port has characteristic of a feeder port for the Port of Singapore, according to the network.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.4
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• pp.131-141
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• 2014

Over the last decade, the Global Navigation Satellite System (GNSS) has been increasingly utilized as a meteorological research tool. The Korea Astronomy and Space Science Institute (KASI) has also been developing a near real-time GNSS precipitable water vapor (PWV) information management system that can produce a precise PWV for the Korean Peninsula region using GNSS data processing and meteorological measurements. The goal of this paper is to evaluate whether the precise point positioning (PPP) strategy will be used as the new data processing strategy of the GNSS-PWV information management system. For this purpose, quality assessment has been performed by means of a comparative analysis of the troposphere zenith total delay (ZTD) estimates from KASI PPP solutions (KPS), KASI network solutions (KNS), and International GNSS Service (IGS) final troposphere products (IFTP) for ten permanent GNSS stations in the Korean Peninsula. The assessment consists largely of two steps: First, the troposphere ZTD of the KNS are compared to those of the IFTP for only DAEJ and SUWN, in which the IFTP are used as the reference. Second, the KPS are compared to the KNS for all ten GNSS stations. In this step, the KNS are used as a new reference rather than the IFTP, because it was proved in the previous step that the KNS can be a suitable reference. As a result, it was found that the ZTD values from both the KPS and the KNS followed the same overall pattern, with an RMS of 5.36 mm. When the average RMS was converted into an error of GNSS-PWV by considering the typical ratio of zenith wet delay and PWV, the GNSS-PWV error met the requirement for PWV accuracy in this application. Therefore, the PPP strategy can be used as a new data processing strategy in the near real-time GNSS-PWV information management system.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.158-165
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• 2020

Buoys are a necessary component for the safety of vessel traffic. However, if the buoy becomes inoperable from damage and loss, it can have significant impact on vessel traffic safety as well as unexpected budget spending. The purpose of this study was to evaluate the risk of accidental contact by applying the marine traffic assessment index that can reflect the traffic flow in the sea area. First, Busan Port No. 5 fairway, with a high number of buoys and many contact accidents, was set as the sea area for assessment. to investigate the status of accidental contact and evaluate risk of contact accidents based on the IALA Waterway Risk Assessment Programme (IWRAP MkII) and Potential Assessment of Risk Model (PARK Model). As a result, buoys are near the P recautionary Area wherein the traffic flow was complicated by the Masan port vessel and Busan new port vessel, and buoys are near the entrance of the Gadeok waterway, wherein vessels show a pattern of navigation across the fairway and buoys are near the breakwater in the inner fairway were considered as high risk for contact accidents. This study can be used as basic data for establishing an integrated model to evaluate the risk of buoy contact accidents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.247-255
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• 2021

The Ulsan anchorage has not secured a sufficient area than the anchorage demand, and the criteria for objective evaluation are not clearly defined. In this study, a general formula to solve the problems of the current anchorage density and occupancy concept was derived, and new adequacy evaluation criteria were proposed. The proposed criteria were applied to the Ulsan E anchorage to evaluate the suitability of the anchorage. The anchorage density and occupancy of the E1 anchorage were 129 % and 122 %, respectively, showing that both evaluation techniques exceeded 100 %, requiring anchorage expansion according to the evaluation criteria. A plan to expand the anchorage was reviewed considering the traffic pattern and the distance from the pilot boarding point. Therefore, a plan to open 35˚ on a sector at the end of the Ulsan No. 1 fairway was developed, and its suitability was verified. Base on the verification results, there was a part of the overlap between the extended area and the traffic track on the south of the E3 anchorage, but the possibility of affecting the marine traffic was minimal. In addition, it was confirmed that anchorage adequacy was achieved.

• Journal of Korean Port Research
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• v.13 no.1
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• pp.133-146
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• 1999

Mokpo coastal area is connected to the adjacent a long river and two large basins. It is essential for port planning coastal zone management and environmental impact study to analyze the data related to the ship operation and variation of current and water quality due to the development of water area including dredging reclamation and estuary barrage. The Yongsan river estuary weir and Yongam-Kumho basins discharge much of water through water gates for the purpose of flood control and prohibit salt intrusion at the inland fresh water area. To meet this purpose discharge through the gates have been done at the period of maximum water level difference between inner river and sea level. This discharged water may cause the changes of current pattern and other environmental influences in the vicinity and inner area of semi-closed Mokpo harbor. In this study ADI method is applied to the governing equation for the analysis of the changes on current pattern due to discharged water. As the results of this study it is known that the discharging operation causes many changes including the increase of current velocity at the front water area at piers approaching passage and anchorages. Discussion made on the point of problems such as restricted maneuverability and the safety of morred vessels at pier and anchorage. To minimize this influence the linked gate operation discharging warning system and laternative mooring system are recommended.