• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.278-286
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• 2020

Reynolds-averaged Navier-Stokes simulations have been performed to investigate an effect of numerical region with high resolution for Kelvin wave around KRISO container ship on its resistance. In the present study, 13 millions cells were used to describe wave profile along the ship hull and Kelvin wave patterns. In order to control a size of numerical region with high resolution for waves around the hull, we employed relaxation zones from a side boundary of numerical domain in which Kelvin wave was suppressed. When the far-field Kelvin wave was not precisely resolved due to the relaxation zone, the instantaneous history of ship resistance was affected although the time average of ship resistance showed -1.15~2.1 % errors. Especially, the damping characteristics of ship resistance in time history was significant when using a large relaxation zone in the side boundary.

• The Korean Journal of Physiology
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• v.1 no.2
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• pp.199-213
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• 1967

Circulatory and respiratory activities were observed in men exposed to the environment of engine room of a cruising Republic of Korea Navy ship and compared to the control values obtained in an ordinary laboratory room on land. The environment of an engine room of cruising navy ship was presumed to be a multiple stress acting on men. The environment of the engine room included high temperature $(35-42^{\circ}C)$, low relative humidity (20-38% saturation), vibration (about 7 cycles per second), rolling and pitching of ship and noises. Sixteen men were divided into two groups consisted of each 8 subjects. Subjects of sea duty group had experience of continuous on board duty averaging 3.5 years. Men of land duty group had no experience of on board activity. On land observations were made on one day prior to the boarding and leaving the port and four days after landing. In between observations in the engine room were made on the first, 5 th, 9 th, 12 th, and 14 th day of on board activity. The whole experimental period lasted for 20 days. Measurements on circulatory and respiratory parameters were at standing resting state (after 30 minutes standing in the case of on land study and 15 minutes in engine room study) and within one minute after cessation of on the spot running of which rhythm was 30/min. and lasted for 5 minutes. Oxygen consumption and pulmonary function test were done in the period of two minutes from the 3rd to 5th minutes of running. The following results were obtained. 1. Body temperature showed no change regardless of group difference or on land or on board measurements. 2. Pulse rate increased markedly after boarding the ship id both groups. Pulse rate increased from the first day on board at rest and after exercise as compared to the on land control value. This increase in pulse rate was more marked after exercise. Sea duty group showed less increase in pulse rate at rest than the land duty group. Standing and resting pulse rate of sea duty group on lam was 81 and increased to 87 at the 5th day on board and remained smaller than the land duty group throughout the period on board. Control standing and resting pulse rate of land duty group on land was 76 and reached 89 at the 9th day on board and thereafter decreased a little. Pulse rate of land duty group at rest on board remained greater than that of sea duty group throughout the period on board. 3. Systolic blood pressure of sea duty group increased after boarding the ship and remained higher than the control value on land. In the land duty group, however, systolic blood pressure decreased during the period on board the ship. Diastolic blood pressure decreased in both groups. 4. Resting breathing rate of land duty group increased and remained higher than the control value on land. In sea duty group, however, resting breathing rate showed a transient increase on the 1st day on board and decreased thereafter to the control value on land and kept the same level throughout the period of cruise. Absolute value of breathing rate in the sea duty group was greater than the land duty group both at rest and after exercise. 5. There was a lowering of breathing efficiency in both groups. Thus, increases in tidal volume and minute ventilation volume and decreases in maximum breathing capacity, vital capacity, capacity ratio and air velocity Index were observed after boarding the ship. An increase in ventilation equivalent was also observed in both groups. The lowering of breathing efficiency was more marked in the land duty group than the sea duty group. 6. Energy expediture increased in both groups during their stay on the ship and was more marked in the sea duty group. 7, Lactate concentration in venous blood at rest and after exercise increased after boarding the ship and no group difference was observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.41-42
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• 2006

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.11
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• pp.953-957
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• 2001

This paper is concerned with a transfer alignment method for the SDINS under ship motions. Major error sources of transfer alignment are data transfer time-delay, lever-arm velocity and ship body flexure. Specifically, to reduce alignment errors induced by measurement time-delay effects, the error compensation method through delay state augmentation is suggested. A linearized error model for the velocity and attitude matching transfer alignment system is first derived by linearizing the nonliner measurement equation with respect to its time delay and augmenting the delay state into the conventional linear state equations. And then it is shown via observability analysis and computer simulations that the delay state can be estimated and compensated during ship motions resulting in considerably less alignment errors.

• Journal of Korea Multimedia Society
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• v.17 no.6
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• pp.687-696
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• 2014

An integrated ship area network has functionality of remote control and autonomous management of various sensors and instruments embedded or boarded in a ship. For such environment, an wireless bridge is essential to transmit control and/or managing information to sensors or instruments from a central integrated ship area network station. In this paper, one of reliable schemes of WiMedia based wireless bridge using relay cooperative transmission using WiMedia distributed MAC protocol is proposed to increase a communication reliability between cluster headers, irrespective of channel variation. Simulation results show that the proposed wireless bridge using relay cooperative transmission scheme increases communication reliability.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.2
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• pp.56-63
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• 1997

This paper is concerned with the design of neural-network based autopilot control system. In this paper, the back-propagation algorithm is introduced and explained in detail. The system identification method based on neural networks for ship motion is developed and its efficacy is verified by using a simple ship maneuvering model. Problems which may arise in a complex maneuvering model are then discussed. The neural-network based system identification method developed in this paper can be used effectively for reconstructing the ship maneuvering moodel which is known to have nonlinearity.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.4
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• pp.369-373
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• 2001

This paper is concerned with a transfer alignment of SDINS under ship motions. To reduce alignment errors induced by the ship body flexure, an error compensation method is suggested based on velocity and DCM partial matching, and by interpreting the simulation results and comparing with the conventional velocity and quaternion partial matching, it is shown that the proposed method is effective enough to improve the azimuth alignment performance.

• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.667-671
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• 2004

This paper describes an development of digital power supply for ship's emergency lighting system(SELS). Proposed system is composed of emergency power supply system(EPSS), half bridge(HB) inverter, fluorescent lamp(FL) starting circuit and microprocessor control system. Experimental works using proposed system confirm that speedy and stable power to be supplied when main power source cut-off, compared with conventional analog type, and control input power up to 35.0［%］ by adjusting pulse frequency of the HB inverter.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.21-27
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• 1991

This paper outlines the method of formulating the bi-cubic B-spline surface of ship hull, employing the open uniform knot vector as well as the periodic uniform knot vector. An appropriate set of B-spline control vertices to generate the B-spline surface is determined by obtaining the pseudoinverse matrix of basis functions. The comparison between the given offsets and the resulting coordinates from the generated ship hull surface shows a good agreement. To check the fairness of the surface Gaussian curvature is calculated on many small subpatches and displayed on the black-and-white plot of the isoparametric net of the surface.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.3
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• pp.309-314
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• 2015

A sunken ship often involves an oil spill. This paper was carried out to minimize environmental and cost damages stemming from oil spil of sunken shipl. Through the analysis of both the standards of the oil tank system and installation, we have identified potential oil spill sites and proposed a remedy of prevention. The result of study, the air pipes of the oil tank are a vulnerable point for oil spill. Also, the remote control devices of emergency shut-off valve have poor accessibility at abandon ship, making it difficult to shut off the emergency shut-off valve. Thus, we propose the addition of a remote quick closing valve in the air pipe and the building of a central control system.