• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.72-77
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• 2010

The Incheon Bridge, which was opened to the traffic in October 2009, is an 18.4 km long sea-crossing bridge connecting the Incheon International Airport with the expressway networks around the Seoul metropolitan area by way of Songdo District of Incheon City. This bridge is an integration of several special featured bridges and the major part of the bridge consists of cable-stayed spans. This marine cable-stayed bridge has a main span of 800 m wide to cross the vessel navigation channel in and out of the Incheon Port. In waterways where ship collision is anticipated, bridges shall be designed to resist ship impact forces, and/or, adequately protected by ship impact protection (SIP) systems. For the Incheon Bridge, large diameter circular dolphins as SIP were made at 44 locations of the both side of the main span around the piers of the cable-stayed bridge span. This world's largest dolphin-type SIP system protects the bridge against the collision with 100,000 DWT tanker navigating the channel with speed of 10 knots. Diameter of the dolphin is up to 25 m. Vessel collision risk was assessed by probability based analysis with AASHTO Method-II. The annual frequency of bridge collapse through the risk analysis for 71,370 cases of the impact scenario was less than $0.5{\times}10^{-4}$ and satisfies design requirements. The dolphin is the circular sheet pile structure filled with crushed rock and closed at the top with a robust concrete cap. The structural design was performed with numerical analyses of which constitutional model was verified by the physical model experiment using the geo-centrifugal testing equipment. 3D non-linear finite element models were used to analyze the structural response and energy-dissipating capability of dolphins which were deeply embedded in the seabed. The dolphin structure secures external stability and internal stability for ordinary loads such as wave and current pressure. Considering failure mechanism, stability assessment was performed for the strength limit state and service limit state of the dolphins. The friction angle of the crushed stone as a filling material was reduced to $38^{\circ}$ considering the possibility of contracting behavior as the impact.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.80-87
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• 2011

Autonomous underwater vehicles (AUVs) present the important advantage of being able to approach the seafloor more closely than surface vessel surveys can. To collect bathymetric data, bottom material information, and sub-surface images, multibeam echosounder, sidescan sonar (SSS) and subbottom profiler (SBP) equipment mounted on an AUV are powerful tools. The 3000m class AUV URASHIMA was developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). After finishing the engineering development and examination phase of a fuel-cell system used for the vehicle's power supply system, a renovated lithium-ion battery power system was installed in URASHIMA. The AUV was redeployed from its prior engineering tasks to scientific use. Various scientific instruments were loaded on the vehicle, and experimental dives for science-oriented missions conducted from 2006. During the experimental cruise of 2007, high-resolution acoustic images were obtained by SSS and SBP on the URASHIMA around the northern Kumano Basin off Japan's Kii Peninsula. The map of backscatter intensity data revealed many debris objects, and SBP images revealed the subsurface structure around the north-eastern end of our study area. These features suggest a structure related to the formation of the latest submarine fan. However, a strong reflection layer exists below ~20 ms below the seafloor in the south-western area, which we interpret as a denudation feature, now covered with younger surface sediments. We continue to improve the vehicle's performance, and expect that many fruitful results will be obtained using URASHIMA.

• Geophysics and Geophysical Exploration
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• v.11 no.1
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• pp.52-59
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• 2008

We have developed a new deep-towed marine DC resistivity survey system. It was designed to detect the top boundary of the methane hydrate zone, which is not imaged well by seismic reflection surveys. Our system, with a transmitter and a 160-m-long tail with eight source electrodes and a receiver dipole, is towed from a research vessel near the seafloor. Numerical calculations show that our marine DC resistivity survey system can effectively image the top surface of the methane hydrate layer. A survey was carried out off Joetsu, in the Japan Sea, where outcrops of methane hydrate are observed. We successfully obtained DC resistivity data along a profile ${\sim}3.5\;km$ long, and detected relatively high apparent resistivity values. Particularly in areas with methane hydrate exposure, anomalously high apparent resistivity was observed, and we interpret these high apparent resistivities to be due to the methane hydrate zone below the seafloor. Marine DC resistivity surveys will be a new tool to image sub-seafloor structures within methane hydrate zones.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.4
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• pp.359-365
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• 2013

There are more than 10 ships and jetfoil passenger ships with speeds of 30~40 kts navigating between Japan and Busan ports per hour. Busan port has the highest density of traffic among the Korean ports and waterways. Jetfoil ships are the most frequently encountered amongst other vessels and about 18 % of passing jetfoil vessels violated port regulations. Based on the analysis of traffic survey carried out for 10 days, jetfoil vessels often overtook other vessels in route and deviated with high speed. This paper verified a proper speed and how to navigate in or out route of jetfoil ships by marine traffic flow simulation. A acceptable navigation speed for jetfoil vessel's mariner was calculated at less than about 32kts in Busan Port. It is a little different that shiphandling difficulty of jetfoil was almost the same whether passing in and out route in Busan Port. This paper proposes that the passing time of jetfoil ships should avoid the peak time to improve the traffic safety in Busan Port.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.20-21
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• 2016

Aids to Navigation (AtoN) is marine traffic safety facility to facilitate the safe and efficient movement of shipping and enhance the protection of the marine environment by the regulation or guideline of The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA). By IALA NAVGUIDE, the term "New Danger" is defined as newly discovered hazards not yet shown in nautical documents and includes naturally occurring obstructions such as sandbanks or rocks or man-made dangers such as wrecks. 'New Dangers' should be appropriately marked using Lateral, Cardinal, Isolated Danger marks or by using the Emergency Wreck Marking Buoy. However, the Emergency Wreck Marking Buoy has difficulties with implementation conditions in terms of speed and accuracy to install the buoy. In case of sinking accidents, it is difficult immediately to install the Emergency Wreck Marking Buoy because of weather conditions, marine environments and accident position. This paper studies Auto Releasing New Danger Mark Buoy on the deck which can be automatically to release from the deck of a vessel and float in the water and quickly install the accident position in case of sinking accidents. The buoy will be to reduce the risk of navigation and prevent secondary collisions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.706-714
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• 2020

Currently, 90 % of the world's population breathes air with a fine dust content exceeding the World Health Organization's annual average exposure limit (10 ㎍/㎥). Global efforts have been devoted toward reducing secondary pollutants and ultra-fine dust through regulations on nitrogen oxides released over land and sea. Domestic efforts have also aimed at creating clean marine environments by reducing sulfur emissions, which are the primary cause of dust accumulation in ships, through developing and distributing environment-friendly ships. Among the technologies for reducing harmful emissions from diesel engines, electrostatic precipitator offer several advantages such as a low pressure loss, high dust collection efficiency, and NOx removal and maintenance. This study aims to increase the durability of a ship by improving equipment quality through failure mode effects analysis for the preventive maintenance of an electrostatic precipitator that was developed for reducing fine dust particles emitted from the 2,427 kW marine diesel engines in ships with a gross tonnage of 999 tons. With regard to risk priority, failure mode 241 (poor dust capture efficiency) was the highest, with an RPN of 180. It was necessary to determine the high-risk failure mode in the collecting electrode and manage it intensively. This was caused by clearance defects, owing to vibrations and consequent pin loosening. Given that pin loosening is mainly caused by vibrations generated in the hull or equipment, it is necessary to manage the position of pin loosening.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.175-179
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• 2006

With the rapid development of oil and chemical industry in the late 20C, massive transportation of oil by oil tanker vessel has grown and it caused the big oil pollution accidents. When oil spill from the oil tanker, damages reach into the astronomical figures in economically and damages affect wide area and many people with break the balance of ecosystem. Recently in Korea, the oil pollution accidents has occurred frequently as growing of oil consumption and it caused large-scale damages to the victim. Oil pollution in Korean offshore takes not only korean fishermen from their life ground and break the ecosystem but it takes too much time and money to recover. To minimize oil pollution damages, it is necessary to make pre-caution effort as a ship owner and relevant government bodies should endeavor to prevent from more damages. But once oil pollution accidents occurs in territorial sea, compensation for victim fishermen is very important. But it is true that compensation is not paid to victim smoothly. So this study aims at the problems of oil pollution compensation to the Korean victim and find the best way to get reasonable compensation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.153-159
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• 2016

Gwangyang traffic safety designated area is composed of 3 fairways (Deep water fairway, inbound fairway, and outbound fairway). However, inbound vessels can't use this passage because of Samyeo rock and artificial fishing banks in inbound route. The problem with the rocks and artificial fishing banks has been raised by ship navigators and authorities of the port. This research is about the safety evaluation and management plan of the passage, and we conducted maritime traffic simulation using a model based on a ship operator risks. As a result, assuming that future marine traffic volume is the same as the present, and if the ship operators use 3 fairways and not two, it showed risk reduction of 46.4 % (vessels over 50,000 DWT using DW route) and 57.1 % (vessels over 10,000 DWT using DW route). Also, in a traffic volume condition which is the same as the present, to induce vessels over 50,000 DWT to use DW route is effective in mitigating of risks. Meanwhile, in a condition which increased the traffic volume by 150 %, it is more effective to induce vessels to use DW route. This research is the result of analysis using the model based on ship operator risks, and not cost-effectiveness analysis on the removal of Samyeo rock and artifical fishing banks. This research is expected to be used on setting up the sea route and management plan (particularly, restriction on passing DW route).

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.15-21
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• 2020

This study analyzes the results of applying the ISO19030 (hull and propeller performance monitoring method) standard to an actual 178 k bulk vessel. Recently, there have been many attempts to apply various energy reduction solutions to vessels to continuously strengthen GHG reduction regulations and secure maritime competitiveness. However, it is not easy to quantitatively analyze the performance of a ship. To resolve these problems, shipping companies, marine paint companies, ship owners, and transportation associations have appointed specialists and standardized the ISO19030 (standard of hull and propeller performance monitoring method) guidelines in 2016 after three years of continuous review. The ISO19030 standard provides methods to monitor hull and propeller performance quantitatively through standardized procedures, thus allowing ship managers to arrive at informed decisions for hull and propeller maintenance, and to evaluate energy-saving solutions and ship-maintenance efficiency. The ISO19030 standard provides a method of analyzing the ship's own performance by collecting the ship's operation and agency data and correcting its environmental and operating factors. In this paper, we apply the ISO19030 standard to three actual ships and propose the ISO19030 application result and the improvement point of the current ISO19030 standard.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.389-401
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• 2016

This study attempted to present the monthly distribution of the inshore gill netters for the prevention of propeller failure caused by the damage of fishing gear by the merchant vessels in the West Sea. This study was conducted using the transmitting device of fishing location (V-Pass) data for 1 year in 2014. The grid intervals are $30minute{\times}30minute$ ($latitude{\times}longitude$) based on the section of the sea. A total of 56 sections were analyzed by constructing a grid. The results revealed that the section no. 194 with the highest density index showed no fishing gear damage accident. But the section no. 193 with a relatively lower density index showed more frequent fishing gear damage accident. It is because the section no. 193 is included in the main route of the merchant vessels. Based on this analysis, it is found that the fishing gears are not damaged in proportion to density index but risk of damage exists according to the main routes of merchant vessels. Therefore, for the safe navigation of the merchant vessels, notifying the waters of $34.5^{\circ}{\sim}35.5^{\circ}$ at latitude and $125.67^{\circ}{\sim}126^{\circ}$ at longitude, as a navigational warning area from May through September, will prevent marine accident, such as propeller failure and fishing gear damage. Accordingly, when the merchant vessels navigate in the section no. 193 and 203, the area of $34.5^{\circ}{\sim}35.5^{\circ}$ at latitude and $125.5^{\circ}{\sim}125.67^{\circ}$ at longitude is recommended for the safe navigation.