• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.19-21
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• 2017

Ship maneuvering performance is usually estimated in calm water conditions which provide valuable information about the ship maneuvering characteristics at the early design stage. However, the course-keeping ability and the maneuvering performance of a ship can be significantly affected by the presence of waves when ship maneuvers in real sea condition. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves in the viewpoint of ship safety in the design stage. In this study, the force and yaw moment acting on a moving ship in regular waves with different wave length and wave direction will be performed in the square wave tank in Changwon National University. The results of this study can be used to help a person to design a ship hull with the best ship maneuverability in waves and disseminate knowledge on predicting ship maneuvering in regular waves in various wave directions.

• Journal of Biomedical Engineering Research
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• v.11 no.1
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• pp.105-112
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• 1990

The main concepts in the design and construction of an motorized wheelchair for loading in the tar which is intended to drive a disabled to long distance. The wheelchair is basically a powered and folding, so it is designed to motorized manual wheel- chair by modularity method. The wheelchair hrs been installed with a power motor module, battery module, and drive & control module. The goal of this project is to develop a wheelchair that has multifunction and operated disabled who has variety impairment. So we ave currently working. Experimental results of the system approach our purpose, which is improved maneuverability, safety and can be loaded.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.555-558
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• 2013

A type of electric propulsion employed by specialized purpose vessels or offshore is the azimuth thruster. Azimuth thruster application had been increasing recently and resulted to excellent vessel maneuverability. However, this system is very complex and some of its major component being exposed under the seawater level presents difficulty in sealing design. For Polar class icebreaker operating in extreme sea condition, this requires a high level of reliability and safety. In this study, the characteristics of lubricating orifice pipe structural vibration installed at the lower reduction gear were investigated and analyzed through beam analysis theory and comparison of experiments. Propeller excitation and the resonant modes of vibration causing excessive vibration and suitable countermeasures to prevent damage due to vibration fatigue on the pipe are presented.

• 한국기계연구소 소보
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• s.13
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• pp.123-141
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• 1984

The safety aspects of ship handing have become increasingly important recently, due to the changes in sea transportation. These are characterizes by larger units, increased traffic density on sea lane, sea transport of dangerous cargo, etc. In addition, as a economic aspect of ship handing, it has obtained an increased attention in connection with port development and consideration of allowable ship size for existing ports. One method for evaluation of maneuvering problems is simulation on a computer by means of a mathematical model of the ship maneuvering motion. The present report describes the elements of a mathematical model for ship maneuvering and gives some results of maneuvering predictions through the simulation.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.50-58
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• 2006

Free running model tests gives us only maneuvering indices not hydrodynamic derivatives. For this reason, system identification method has been applied to the measured data to identify mathematical model describing hydrodynamic force. However It is difficult to obtain complete set of maneuvering derivatives because of strong correlation of sway velocity and yaw rate. Therefore, in this paper, we assumed that sway velocity related coefficients would be obtained by oblique towing test. and then proposed new procedure to estimate yaw related coefficients. To do this, correlation and regression analyses were carried out to establish modified model and estimate maneuvering derivatives. Also D-optimal rudder input scenario was found based on the modified model and confirmed the validity of its sufficient richness as a input scenario.

• Journal of Navigation and Port Research
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• v.46 no.2
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• pp.82-91
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• 2022

When a ship moves in the proximity of the lateral bank, bank suction forces are generated due to bank effects. Thus, hydrodynamic forces can significantly impact the ship's maneuverability and navigation safety. In this study, model tests were performed to investigate the hydrodynamic forces exerted on a ship, especially suction forces caused by bank effects, using captive model and bank effect tests. A low-speed condition was selected in this study, because of the perilous situation as the ship moves close to the bank. The accuracy of the hydrodynamic forces exerted on the hull was verified, by comparing the results of the static drift test with the results obtained from other institutes at design speed. The straight simulation caused by bank effects was then implemented using estimated hydrodynamic coefficients.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.142-143
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• 2023

A contact accident with gantry cranes involving the container ship MV Milano Bridge in Busan New Port took place on 6 April 2020. The report concluded that the pilot unreasonably piloted the ship with impaired maneuverability and without a proper pilotage plan. Analyzing the entire system by CAST model gives a holistic approach in linking all the key components and their roles as well as violations that led to the accident, stepping away from placing the blame on only one component in the system. Furthermore, analyzing the accident as an system theory gives a clear overview of the relationships between system components and how these interactions led to the accident.

• Journal of Korean Physical Therapy Science
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• v.30 no.4
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• pp.1-8
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• 2023

Background: This study evaluates the usability of the Motion-Tracking Gait Assistive Walker (MTGAW) designed for elderly individuals and those with disabilities, identifying areas for improvement through interviews with physical and occupational therapists. Design: A survey study involves the usability test for MTGAW. Methods: Usability evaluations were conducted with 37 physical therapists and occupational therapists. The process included explanation, product usage, satisfaction surveys, and interviews. A satisfaction survey covering 19 items across safety, maneuverability, usability, and management areas was administered. Individual interviews identified areas for improvement. Results: Overall, high satisfaction was reported across the four areas, but interviews highlighted the need for improvements, such as addressing discomfort due to slow speed and enhancing safety measures to prevent rear-end falls. Adjusting the walker's height and width to suit the user's physique was also suggested. Conclusion: MTGAW enhances walking support and hand movement freedom but needs refinement in speed control, fall prevention, and customization based on the user physique. Future efforts should focus on developing an improved MTGAW, considering recommendations from physical therapy experts, and conducting studies to analyze its clinical effectiveness for commercialization.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1738-1748
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• 2019

Previous research has shown that the inclined condition has an impact on the natural circulation (natural circulation) mode operation of Floating Nuclear Power Plant (FNPP) mounted on the movable marine platform. Due to its compact structure, small volume, strong maneuverability, the Integral Pressurized Water Reactor (IPWR) is adopted as marine reactor in general. The OTSGs of IPWR are symmetrically arranged in the annular region between the reactor vessel and core support barrel in this paper. Therefore, many parallel natural circulation loops are built between the core and the OTSGs primary side when the main pump is stopped. and the inclined condition would lead to discrepancies of the natural circulation drive head among the OTSGs in different locations. In addition, the flow rate and temperature nonuniform distribution of the core caused by inclined condition are coupled with the thermal hydraulics parameters maldistribution caused by OTSG group operating mode on low power operation. By means of the RELAP5 codes were modified by adding module calculating the effect of inclined, heaving and rolling condition, the simulation model of IPWR in inclined condition was built. Using the models developed, the influences on natural circulation operation by inclined angle and OTSG position, the transitions between forced circulation (forced circulation) and natural circulation and the effect on natural circulation operation by different OTSG grouping situations in inclined condition were analyzed. It was observed that a larger inclined angle results the temperature of the core outlet is too high and the OTSG superheat steam is insufficient in natural circulation mode operation. In general, the inclined angle is smaller unless the hull is destroyed seriously or the platform overturn in the ocean. In consequence, the results indicated that the IPWR in the movable marine platform in natural circulation mode operation is safety. Selecting an appropriate average temperature setting value or operating the uplifted OTSG group individually is able to reduce the influence on natural circulation flow of IPWR by inclined condition.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.867-874
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• 2021

The IoT (Internet of Things) technology is rapidly becoming an important consideration in many engineering fields in the current 4th industrial era. In recent years, the concepts of digital shipbuilding and smart factories have been adopted as trends in shipyards. However, there is active interest in research on implementing autonomous driving in autonomous vehicles and airplanes, which is currently available in commercial form in a limited capacity. The present study is regarding the path-tracking performance of a boat to accomplish an autonomous driving mission using a flight controller (FC) and real-time kinematic (RTK) global positioning system (GPS) based on an open-source Ardupilot; an actual sea test is also performed using this system on a calm lake. The boat's mission is to evaluate the maneuverability of the self-driving process to a specific point and returning to the home position. For a given speed, the difference between the preset mission trajectory and actual operational trajectory was analyzed, and a series of studies were conducted on the applicability of the system to ships. In addition, the movements and maneuverability of the OmniX-type hull with four propellers were investigated, and the driving path-tracking performance was observed to increase by a maximum of 48%.