• Journal of Advanced Research in Ocean Engineering
• /
• v.4 no.3
• /
• pp.115-123
• /
• 2018

This study was carried using the new approach method to design appropriately the Loading Arm length and the alarm setting according to ship movements on Loading and Unloading marine Berth. The quasi-static mooring analysis was performed to estimate 110,000DWT ship's movements based on environmental conditions such as wind, current and wave. The mooring motion of the ship is very important to determine the loading arm scope, and in this case, the operation condition is performed on the ship without considering the damaged condition of the mooring line because the ship movement in case of damage is larger than intact, and all operations are stopped, the loading arm being released due to control system. From the result of mooring analysis, motion displacements, velocities and accelerations were simulated. They were used to simulate the maximum drifting speeds and distances. The maximum drifting speeds were checked to be satisfied within drifting speed limits. The total maximum drifting distances were simulated with alarm steps of the new approach method. Finally, the loading arm envelopes using the total maximum drifting distances were completed. Therefore, it was confirmed that the new approach method for loading arm envelopes and alarm settings was appropriate from the above results. In the future, it will be necessary to perform the further advanced dynamic mooring analysis instead of the quasi-static mooring analysis and to use the precise computer program analysis for various environments and ship movement conditions.

• Journal of Ocean Engineering and Technology
• /
• v.37 no.4
• /
• pp.158-163
• /
• 2023

Objects adrift can cause considerable damage to coastal infrastructure and property during tsunami and storm surge events. Despite the potential for harm, the drifting behavior of these objects remains poorly understood, thereby hindering effective prediction and mitigation of collision damage. To address this gap, this study employed a motion analysis program to track a drifting container's location using images from an existing laboratory experiment. The container's trajectory and velocity were calculated based on the positions of five markers strategically placed at its four corners and center. Our findings indicate that the container's maximum drift velocity and distance are directly influenced by the scale of the solitary wave and inversely related to the container's weight. Specifically, heavier containers are less likely to be displaced by solitary waves, while larger waves can damage coastal structures more. This study offers new insights into container drift behavior induced by solitary waves, with implications for enhancing coastal infrastructure design and devising mitigation strategies to minimize the risk of collision damage.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.31 no.4
• /
• pp.350-361
• /
• 1995

For the Purpose of the measurement of drifting condition of the anchovy drift gill net, some experiments were carried out in M. S Seong-Yang at the near sea of Kampo harbor in Korean east sea from August to October 1994, by using three set of GPS equipped with her net. The main results obtained are as follows : 1) In fixed position by GPS at Taebyon, the radius of 95% probability and shifted distance from standard position were respectively 79.8m, 21.0m. 2) The mean values of PDOP and HDOP of GPS at Taebyon were respectively 3.5, 1.9 and the stability of the position by GPS at Taebyon was found to be very high. 3) In the fishing ground of the position from Lat. $35^{\circ}$ 41.5'N to $Lat^{\circ}$. 43.5', from Long. $129^{\circ}$ 32.0'E to Long. $129^{\circ}$ 32.5'E, the direction of the whole stretched drift gill net was $190^{\circ}$ and the direction of the whole casted net was $200^{\circ}$ when casting the net was finished. When whole net was found to be drifting into the direction of $170^{\circ}\;to\;180^{\circ}$, and the mean drifting speed of that was 0.82kt. 4) In the fishing ground of the position from Lat. $35^{\circ}$ 44.0'N to Lat. $35^{\circ}$ 45.2'N, from Long. $129^{\circ}$ 30.1'E to Long. $129^{\circ}$ 31.2'E, the direction of the whole stretched net was 20$^{\circ}$ and the direction of the whole stretched net was $20^{\circ}$ when casting the net was finished. When hauling the net, the direction of the spreaded net appeared from the North into the South and the whole net was found to be drifting into the direction of $210^{\circ}\;to\;220^{\circ}$, and the mean drifting speed of that was 0.75kt. 5) In the fishing ground of the positioning from Lat. $35^{\circ}$ 44.9'N to Lat. $35^{\circ}$ 46.0'N, Long. $129^{\circ}$ 33.0'E to Long. $129^{\circ}$ 34.0'E, the direction to the whole stretched net was $35^{\circ}$ and the direction of the whole casted net was $50^{\circ}$ when casting the net was finished. When hauling the net, the direction of the spreaded net appeared into the South from the East and the whole net was found to be drifting into the direction of $330^{\circ}\;to\;40^{\circ}$, and the mean drifting speed of the was 0.63kt.

• Industry Promotion Research
• /
• v.8 no.1
• /
• pp.143-150
• /
• 2023

Cui Pu Korea period official, 1487 AD to Jeju Island to perform official duties, after the death of his father, in 1488 leap on the third day of the first month home, unfortunately encountered a storm on the way, and drifting in the sea nearly half a month later, finally landed in the "Datang state Zhejiang Taizhou Prefecture near the Hai county border" (now Sanmen county). Cui Pu traveled overland from Taizhou to Hangzhou, then via Hangzhou, by boat along the Beijing-Hangzhou Grand Canal to Beijing, and then by land from Beijing through Shanhaiguan Pass, through the Yalu River back to his motherland. We have pieced together the distance he traveled, the current situation of the places he passed through. He also hopes to make a new record of the changes of these sites by revisiting the important sites he has walked. This study explores Cui Pu's footprints and reviews the history by comparing the ancient and modern places he passed through.

• 한국해양학회지
• /
• v.30 no.1
• /
• pp.27-38
• /
• 1995

For the study of oceanic surface current, this work presents a system design which is composed of three parts, a Global Positiong System(GPS) unit, a transmitter with radio frequency (RF) modem and an antenna which are housed in a plastic spherical buoy, and computerised of VHF receiving system. The key idea for this study is to employ a commercially available GPS on a drifting buoy and to utilize the receiver position information from the buoy in determining the Lagrangian motion of surface ocean waters. Great efforts has been paid to the system design which would demand several points in harsh conditions common in the sea surface, that is power supply problems housed inside of a plastic buoy, optimizing transmitting radio frequency which limits transmitting distance to a receiving station. for all these difficulties, the system appears to be promising in future oceanic applications and is considered to economical compared to ARGOS drift buoy which is being used by commercial base. We believe that the system needs to be improved in terms of several aspects such as a longer transmitting distance, a power supply and software. for the test experiments in situ, the system has employed off the coast of Ku Ryong Po int the southeast part of Korea and successfully collected the surface current data. The results are presented for two cases from 21 to 31, March 1994 and 21 to 25, June 1994 in terms of current statistics and trajectories of drifting buoys.

• Journal of Ocean Engineering and Technology
• /
• v.35 no.3
• /
• pp.173-182
• /
• 2021

The maneuvering performance of a ship on the actual sea is very different from that in calm water due to wave-induced motion. Enhancement of a ship's maneuverability in waves at the design stage is an important way to ensure that the ship navigates safely. This paper focuses on the maneuvering prediction of a Russian trawler in wind and irregular waves. First, a unified seakeeping and maneuvering analysis of a Russian trawler is proposed. The hydrodynamic forces acting on the hull in calm water were estimated using empirical formulas based on a database containing information on several fishing vessels. A simulation of the standard maneuvering of the Russian trawler was conducted in calm water, which was checked using the International Maritime Organization (IMO) standards for ship maneuvering. Second, a unified model of seakeeping and maneuvering that considers the effect of wind and waves is proposed. The wave forces were estimated by a three-dimensional (3D) panel program (ANSYS-AQWA) and used as a database when simulating the ship maneuvering in wind and irregular waves. The wind forces and moments acting on the Russian trawler are estimated using empirical formulas based on a database of wind-tunnel test results. Third, standard maneuvering of a Russian trawler was conducted in various directions under wind and irregular wave conditions. Finally, the influence of wind and wave directions on the drifting distance and drifting angle of the ship as it turns in a circle was found. North wind has a dominant influence on the turning trajectory of the trawler.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.15 no.1
• /
• pp.35-42
• /
• 1979

This paper concerns the receding of the eastern coastline of Korean peninsula at a macroscopic point of view, the result is as following. 1. Eastern coast is gradually developed from maturity stage to full maturity stage. 2. The coastline recession due to sea level rise is amounted to the receding distance, x=0.045 m per yr. 3. The author proposes another classification from the new view point, which is classified by comparing quantities between river supplying sediment loads, and the littoral drifting due to wave actions. According this, eastern coast is receding(Type Q-A), and we could find it's geomorphological characteristics. 4. The general piofile of eastern coast sand beach is erosional storm profile(Type I) which accompany offshore bar. 5. From the wave measuring data of eastern coast(Hoopo port), I can derive the linear regression line of the exceedance probability of wave height from the log-normal distribution. $z=O. 113+4.335 log_lo H, r=0.983.$ Above equation made it possible to estimate $\omega[=P(H>H_c)]for the effective wave height H_c=2. Om4, 4. Om and their corresponding values are considerable (7.8%, 0.3%) 6. Eastern coastline certainly have the tendency of erosive and receding, owing to the sea level rise, poor sediment source and effective wave actions. It's very desirable to survey coastline evolution for a long time systematically, in order to make more elaborate diagnosis.

• Current Optics and Photonics
• /
• v.3 no.1
• /
• pp.27-32
• /
• 2019

We present an autofocus tracking system implemented by the digital refocusing of digital holographic microscopy (DHM) and the tunability of an electrically tunable lens (ETL). Once the defocusing distance of an image is calculated with the DHM, then the focal plane of the imaging system is optically tuned so that it always gives a well-focused image regardless of the object location. The accuracy of the focus is evaluated by calculating the contrast of refocused images. The DHM is performed in an off-axis holographic configuration, and the ETL performs the focal plane tuning. With this proposed system, we can easily track down the object drifting along the depth direction without using any physical scanning. In addition, the proposed system can simultaneously obtain the digital hologram and the optical image by using the RGB channels of a color camera. In our experiment, the digital hologram is obtained by using the red channel and the optical image is obtained by the blue channel of the same camera at the same time. This technique is expected to find a good application in the long-term imaging of various floating cells.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.4
• /
• pp.338-347
• /
• 2023

Jinhae Bay, characterized by frequent runaway ships and strong winds during typhoon attacks, poses a high risk of maritime accidents such as ship collisions and groundings. This study aims to determine a safe separation distance between ships in the Jinhae Bay anchorage, considering the unique environmental characteristics of the Korean sea area. Analysis revealed that an average of 100-200 ships anchor in the typhoon avoidance area in Jinhae Bay during typhoon attacks, with approximately 70% of ships experiencing anchor dragging owing to strong external forces exceeding 25 m/s wind speeds. In this study, we analyzed and presented the separation distances between ships during anchoring operations based on domestic and international design standards, separation distances between ships used as actual typhoon shelters in Jinhae Bay, and appropriate safe distances for ships drifting under strong external forces. The analysis indicated that considering the minimum criteria based on the design standards and emergency response time, a minimum safe distance of approximately 400-900 m was required. In cases where ample space was available, the separation distance was recommended to be set between 700 to 900 m. The findings of this study are anticipated to contribute to the development of guidelines for establishing safe separation distances between ships seeking refuge from typhoons in Jinhae Bay in the future.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.4
• /
• pp.227-235
• /
• 1977

The noise pressure scattered underwater on account of the engine revolution of a pole and liner, Kwan-Ak-San(G. T. 234.96), was measured at the locations of Lat. $34^{\circ}47'N$, Long. $128^{\circ}53'E$ on the 16th of August 1976 and Lat. $34^{\circ}27'N$, Long. $128^{\circ}23'E$ on the 28th of July, 1977. The noise pressure passed through each observation point (Nos. 1 to 5), which was established at every 10m distance at circumference of outside hull was recorded when the vessel was cruising and drifted. In case of drifting, the revolution of engine was fixed at 600 r. p. m. and the noise was recorded at every 10 m distance apart from observation point No. 3 in both horizontal and vertical directions with $90^{\circ}$ toward the stern-bow line. In case of cruising, the engine was kept in a full speed at 700 r.p.m. and the sounds passed through underwater in 1 m depth were also recorded while the vessel moved back and forth. The noise pressure was analyzed with sound level meter (Bruel & Kjar 2205, measuring range 37-140 dB) at the anechoic chamber in the Institute of Marine Science, National Fisheries University of Busan. The frequency and sound waves of the noise were analyzed in the Laboratory of Navigation Instrument. From the results, the noise pressure was closely related to the engine revolution shelving that the noise pressure marked 100 dB when .400 r. p. m. and increase of 100 r. p. m. resulted in 1 dB increase in noise pressure and the maximum appeared at 600 r. p. m. (Fig.5). When the engine revolution was fixed at 700 r. p. m., the noise pressures passed through each observation point (Nos. 1 to 5) placed at circumference of out side hull were 75,78,76,74 and 68 dB, the highest at No.2, in case of keeping under way while 75,76,77,70 and 67 dB, the highest at No.3 in case of drifting respectively (Fig.5). When the vessel plyed 1,400 m distance at 700 r.p.m., the noise pressure were 67 dB at the point 0 m, 64 dB at 600m and 56 dB at 1,400m on forward while 72 at 0 m, 66 at 600 m and 57 dB at 1,400 m on backward respectively indicating the Doppler effects 5 dB at 0 m and 3 dB at 200 m(Fig.6). The noise pressures passed through the points apart 1,10,20,30,40 and 50 m depth underwater from the observation point No.7 (horizontal distance 20 m from the point No.3) were 68,75,62,59,55 and 51 dB respectively as the vessel was being drifted maintaining the engine revolution at 600 r. p. m. (Fig. 8-B) whereas the noise pressures at the observation points Nos.6,7,8,9 and 10 of 10 m depth underwater were 64,75,55,58,58 and 52 dB respectively(Fig.8-A).