• Journal of Advanced Navigation Technology
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• v.20 no.3
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• pp.232-237
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• 2016

As a possible standardization of wireless local area network (WLAN), IEEE 802.11 LRLP is under discussion in order to support long range and low power (LRLP) communication for internet of things (IoT) including drones and many other IoT devices. In this paper, an efficient adaptive resource unit allocation scheme for uplink multiuser transmission in IEEE 802.11 LRLP networks is proposed. In the proposed scheme, which adopts OFDMA random access based transmission scheme of IEEE 802.11ax, in order to enhance the efficiency of the slotted OFDMA random access, access point (AP) traces the history of the sizes of successfully transmitted uplink data, and adjusts the sizes of resource units for the next uplink multiuser transmission adaptively. Our simulation results corroborate that the proposed scheme significantly improves the system throughput.

• Journal of Navigation and Port Research
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• v.34 no.8
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• pp.623-628
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• 2010

High speed marine vehicle, such as semi-planing, planing craft have been developed recently. These ships paid attention to the resistance characteristics, especially in high speed region. Model test method is divided to two equipment greatly, first 'Towing tank', second 'C.W.C.'. It is difficult to estimate a resistance characteristics for high speed boat. because these are made for low speed ship. This paper suggests a new model test method and system. This is real sea model test and it's comprised of eight part. Firstly, This method is tested at C.W.C that is possible to using in real sea model tes using low speed boat modelt. And then, Real sea model test and CFD calculation are performed and compared with tow way used high speed boat model. It can be a good way to estimate a performance for high speed boat.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.71-76
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• 2005

Many sea accidents such as collisions and groundings of vessels were occurred due to the lack of sufficient manoeuvring capability of vessels. Therefore IMO adopted 'The interim standards of ship manoeuvrability by Resolution A.751(18) and the standards have been applied to vessels of 100m or more in length and all chemical tankers and gas carriers regardless of the length, which were constructed on or after 1 July 1994. The IMO manoeuvrability standards are divided into three kinds as bellows; (1) Turning capability standards : Estimated values in design stage are to be certified by turning circle test of the actual vessel. (2) Course keeping quality standards : Estimated values in design stage are to be certified by $10^\sqsubset\;and\;20^\sqsubset$ Zig-Zag tests of the actual vessel. (3) Shortest stopping distance standards : Estimated values in design stage are to be certified by the shortest stopping distance tested by the actual vessel. In this paper, the authors computed the values of the manoeuvring standards of several vessels from their original design and compared them with those results from experiments of the model ships and also examined the values and concluded about the validity of IMO Manoeuvrability standards.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.384-389
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• 2021

An optimal ground station (GS) antenna pattern design method for network-based UAV command and control communication systems considering complexity and performance is presented. The GS antenna consists of multiple side sectors and one upward sector. The antenna gain for each vertical/horizontal angle of the GS antenna according to the change of antenna design parameters such as the number of sectors, horizontal and vertical beam-width, and tilt-angle is modeled, and the effect of the parameter changes on the signal-to-noise ratio (SNR) distribution in the virtual three-dimensional space is analyzed. It is observed that the tilt-angle of the side sectors has the greatest effect on the performance, and the longer the distance between GSs, the higher the maximum altitude and the smaller the number of side sectors, the tilt-angle should be lower. In addition, it is observed that the wider vertical beam-width of the side sector is advantageous in maximizing the lowest SNR, but narrow vertical beam-width is advantageous in maximizing the average SNR.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.2
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• pp.79-94
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• 2021

A GNSS receiver installed in autonomous vehicles is the most essential device for its navigation. However, if an intentional jamming signal is generated, there is a risk of exposure to an accident risk due to deterioration of the GNSS sensor's performance. Research is required to prevent this, and accordingly, a jamming generating device must be provided. However, according to the provisions of the law related to jamming, this is illegal. In this paper, we implement an in-vehicle jamming device that complies with the provisions of the law and does not affect the surrounding GNSS sensors. Driving simulation is used to evaluate the performance of the GNSS algorithm, and the malfunction of autonomous vehicles occurring in the interference environment and data errors output from the GNSS sensor are analyzed.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.114-124
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• 2019

The drone market, an unmanned aerial vehicle, is rapidly expanding and developing into an important area related to the huge changes in the traffic system of the future. With various technologies on the fourth industrial revolution, including drones, mentioned at the Davos Forum in January 2016, interest in drones is emerging as an explosive demand for national certificates. The number of drone pilots, which was only 400 in 2015, is continuing to surpass 17,000 as of 2018. Therefore, this study analyzed the safety perception of the pilots based on the DREEM (Dundee ready environmental assessment) model designed to evaluate the educational environment along with the current state of drone education in Korea. This led to the conclusion that the high level of satisfaction of the pilot with the educational environment contributes to the overall safety perception, including compliance with procedures.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.465-470
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• 2020

Complex materials are widely used in aviation industries where lightweighting is essential because they have lighter properties than metals. However, composite materials can cause defects such as internal void formation, poor adhesive mixing, and non-adhesive parts during the production process, and there is a risk of micro-cracking and interlayer separation due to low energy impact. Therefore, a structural damage test is essential. As a result, structural integrity monitoring using FBG is drawing attention. Compared to conventional electrical sensors, FBG has the advantage of being more corrosion-resistant and multiplexed without being affected by electrical noise. However, interloggers measuring FBG are expensive and have a large disadvantage because they are made on the premise of measuring large structures. In this paper, low-cost interloggers were designed for use in unmanned or small aircraft using optical switche, WDM filter, and LTFs, and compared to conventional high-priced interrogator.

• Journal of Advanced Navigation Technology
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• v.25 no.4
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• pp.273-279
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• 2021

A flight control computer(FLCC) applied to an unmanned aerial vehicle(UAV) is a safety-critical item, and which is designed in a multiple structure to increase the reliability of operation by securing fault tolerance. These FLCC of multiple structure should be designed so that each independent processing/control components can perform the same operation at the same time. And for this reason, a synchronization algorithm for synchronizing the operation between FLCCs should be included in an operational flight program. In this paper, we propose a software design method for synchronization between dual FLCCs applied to UAVs. The proposed synchronization method is designed to synchronize using only the minimum hardware resources to reduce a failure rate. In addition, the proposed synchronization method is designed to minimized synchronization errors due to a timer operation by designing in consideration of operation characteristics of the hardware timer used for the synchronization.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.519-527
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• 2023

Air-launch means launching from aircraft such as fighter jets, and has various advantages, such as cost reduction and less environmental/weather impact during launch. However, there are no air-launch satellite in Korea. Examining air-based launch satellite and anti-satellite missiles operated and developed by foreign private companies and various countries confirmed the necessity of domestic research and development. In South Korea, various research activities, including satellite launch system design and development approaches for different launch platforms, have been carried out mainly by academia. Development of upward maneuver air launch technology which is launched in the air when the aircraft is moving upward is suggested. Additionally, an introduction to wind tunnel tests for safety separation verification is provided. A new concept for a test facility has been suggested to conduct drop tests.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.122-123
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• 2023

About 1 year and 7 months have passed since the Serious Accident Punishment Act was implemented, and although many studies have been conducted on the definition and policy of the Act, almost no research has been conducted on its impact on the logistics industry. In particular, research on the PDI (PRS) process within finished vehicle logistics is severely lacking ‥‥‥. The government is expecting to expand the scope of punishment and upgrade the safety management system through the Serious Accident Punishment Act, but if you check the industrial accident data issued by the Ministry of Employment and Labor in 2022, the number and rate of industrial accidents will increase compared to 2021