• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.4
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• pp.348-357
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• 2024

Maneuvering performance is crucial for fishing vessels, especially under operational conditions that involve frequent course changes and weight variations due to catch. Small vessel accidents account for approximately 60% of maritime incidents as of 2022, mainly attributed to collisions and stranding accidents due to insufficient maneuvering performance. Especially, accidents that occur on small vessels less than 10 tons account for about 65% of all accidents. The absence of international standards presents challenges in accurately evaluating the maneuvering performance of small vessels. In this study, a 4.99-ton small fishing vessel was selected as the target, and a 3d-cad model was created. The commercial numerical analysis program STAR-CCM+ was employed to establish a simulation environment for the vessel's maneuvring motion. Based on this standard loading conditions and weight distribution were considered, 10° / 10°, 20° / 20° zigzag tests and 35° turning test were conducted. The results revealed a tendency for decreased yaw and course-keeping performance and improved turning performance as the hull weight increased. However, in partial arrival and full load departure condition, the manoeuvering performance were relatively poor. Based on this, the need for evaluation of maneuvering and standardized criteria of maneuvering performance for safe navigation of small vessels is presented. Furthermore, it is expected that the evaluation results of maneuvering performance in this study can serve as fundamental data for establishing criteria for evaluating the maneuvering performance of small vessels.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.240-248
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• 2016

As a new technical approach, the achievement of an eco-environmental leisure boat with a photovoltaic system is attempted by simultaneously actuating nine photovoltaic solar panels, in association with an applied sail control system by use of wind. In this approach, the photovoltaic system consists of a solar module, an inverter, a battery, and relevant components, while the sail control device is equipped with a sail up/down and mast-turning instrument. Furthermore, this research conducts a performance evaluation of the manufactured prototype and acquires the purposed quantity value and the development purpose items. The significant items-sail up/down speed (seconds) and mast turning angle (degrees)-are evaluated during the performance test. In the process of the performance evaluation, a wind direction sensitivity of 90% and a maximum instant charging power of 900 W were also obtained. In addition, the maximum sail time is evaluated in order to acquire the optimum quantity.

• Journal of Ocean Engineering and Technology
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• v.30 no.1
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• pp.57-67
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• 2016

As a new technical approach, an attempt was made to realize a photovoltaic system for an eco-environmental leisure ship by simultaneously actuating nine photovoltaic solar panels in association with the application of a sail-controlling system using wind energy. In this approach, the photovoltaic system consisted of a solar module, an inverter, a battery, and the relevant components, while the sail-controlling device was equipped with sail up/down and mast turning systems. The previously mentioned eco-environmental leisure ship utilizes a photovoltaic hybrid system that uses solar and wind energy as renewable energy sources. Furthermore, this research included a performance evaluation of the manufactured prototype, the acquisition of the purposed quantity values, and development of the purposed items. The significant items, including the sail up/down speed (seconds) and mast turning angle (degrees) were evaluated for a performance test. A wind direction sensitivity of 90% and maximum instant charging power of 900 W were also obtained in the process of the performance evaluation. In addition, the maximum sail time was also evaluated in order to acquire the optimum value. The performance evaluation showed that the prototype with a photovoltaic hybrid system was suitable for sailing an eco-environmental leisure ship using solar and wind energy.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.26-33
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• 2001

Thrust vector control system is control device which is mounted exit of the nozzle to generate pitch, yaw and roll directional force by deflecting flow direction of the supersonic jet from the nozzle. By obtaining control force, jetvane which is exposed in jet flow is working thermal and aerodynamic load. Axial thrust loss and side thrust is affected by shock patterns and interactions between jetvanes according to jetvane geometry and turning angle. In this study, we designed 6 types of jetvane to evaluate pitch, yaw and roll characteristics of ietvane in supersonic flow, and perform the cold flow test in range of turning angles of jetvanes between $0^{\cire}$ and $25^{\cire}$ by $5^{\cire}$ respectively. Also, calculation is going side by side to analyse flow interaction. Results show that there is no interactions between jetvanes upto turning angle 20$^{\circ}$, chord and lead length ratio is very important parameter to aerodynamic performance and maximum thrust loss is appeard to 17% of axial thrust in roll directional control.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.2
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• pp.77-80
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• 1982

The maneuverabilities of 240 GT class skipjack pole and liner were studied, based on the maneuvering indices and the data which were obtained from Z test of the experimental ship, the m.s. KWANACKSAN, the training ship of the National Fisheries University of Busan. The maneuvering indices K' of the experimental ship were 0.611(at 10$^{\circ}$Z test), 0.622(at 20$^{\circ}$Z test) and 0.556(at 30$^{\circ}$Z test). Her maneuvering indices T' were 1.094(at 10$^{\circ}$Z test), 1.695(at 20$^{\circ}$Z test) and 1.367(at 30$^{\circ}$Z test). The above calculated values K', T' showed that her turning ability at helm angle 20$^{\circ}$ and her obeying ability at helm angle 10$^{\circ}$ were most effective. As it appeared that the calculated K'-values of the experimental ship were smaller than the standard K'-values of different kinds of ships and her overshoot angles at her Z test were greater than those of them, her turning ability was found to be lower. When the experimental ship took a turn at her 10$^{\circ}$Z test, running distance was about 8.3 times her own length and didn't exceed the standard maneuvering distance, 5 to 11 times ship's own length, therefore she was considered to have good maneuverabilities synthetically.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.171-176
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• 1997

In this paper, We have analyzed dynamic characteristics of cutting force. Test materials are used martensitic heat resisting steel, STS420J2. The obtained results are as follows: 1. Cutting force is smaller make small feed when feed speed make a change. 2. Principal cutting force is smaller make small cutting speed when feed speed make a change.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.63-67
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• 2000

A tool holder system has been designed to measure cutting forces in diamond turning. This system includes a 3-component piezo-electric tranducer. In this research, tool holder system is modeled by considering the element dividing, material properties, and boundary conditions using MSC/PATRAN. Mode and frequency analysis of structure is simulated by MSC/NASTRAN, for the purpose of developing the effective design. In addition, tool holder system is verified by vibration test using accelerometer. This system will aid to the development of Fast Tool Servo (FTS)

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.285-286
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• 2014

Recently, the unipolar gate power source is preferred in inverter system because of cost reduction reason. In this case, designer uses 0V source for turning-off the switching devices instead of negative voltage at Vee source. If the gate driver circuit has some stray inductance, the gate voltage would happen a surge voltage. This paper analyzes that of stray inductance effect during the switching behavior in the circuit and the proposed solutions were verified by pulse test.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.83-87
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• 2001

A 110 mm diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fabricated by ultra-precision single point diamond turning (SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an Al substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of $Ra={\lambda}/12({\lambda}=632nm)$ has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated Al alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.3
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• pp.239-245
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• 2018

International Maritime Organization (IMO) has established standards for ship manoeuvrability and applied these standards for vessels over 100 meters in length that built since 2004 (IMO, resolution MSC.137[76]). These standards are no exception to fishing vessels. In this study we carried out a manoeuvring simulation of the new model ship (Stern trawler) of fisheries training ship of Pukyong National University based on Kijima's empirical formula. The formula takes into account of the effect of stern shape or does not take into account of the effect of stern shape. Also we checked whether the simulation results of turning motion of model ship meet IMO manoeuvrability criteria and then compared trajectories between the simulation results of model ship and the results of real sea trial test of the existing ship. In conclusion, Kijima's empirical formulas can estimate the manoeuvrability of fishing vessels at design stage approximately, it needs more parameters of fishing vessel own in case of expressing the manoeuvrability of fishing vessel accurately.