• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.305-313
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• 2007

The aim of present paper is to investigate the dynamic strength characteristics of LNG cargo containment system under sloshing impact loads numerically. The dynamic stress transmission mechanism under the impact load was analyzed based on the dynamic Finite Element Analysis. Based on the insights obtained from the numerical studies, the characteristics of internal stress distribution and stress concentration have been reported. The material option including anisotropic material features required for the commercial FEA code application were suggested based on the comparison with the experimental results.

• Proceedings of the Safety Management and Science Conference
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• 2005.05a
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• pp.199-212
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• 2005

Many countries of the world is driving forward development of large-scale hub port. They are now pushing ahead with setting up of effective marketing strategies to survive in keen competitions of the 21st century port industry. The port is of ever increasing importance for the bridge connecting sea and road transportation in handling international cargoes. The port, differently from general working places, is a closed area required for security, customs, and quarantine procedures. The loading and unloading is being done differently by ports, cargoes, and ships. To do loading and unloading, a lot of equipment and different types of labor are required, which flow is complicated and safe management is essential. As above mentioned the port is very unique and very deteriorated working place in its working environment. The purpose of this study is to propose ways to reduce and prevent from port accidents. As first step to do this, we have collected 923 accidents happened at Incheon Port during the period of 1994 to 2003. We have thoroughly analyzed characteristics, harmfulness, and risk of the loading/unloading they have done, as well as the accident frequency and relationship between the accidents. As second step to further analyze, We have employed DMAIC technology, an advanced process of 6 sigma presently in spotlight as the best program for management innovation. This analysis results in recognition of important accident characteristics, causes and effects analysis, critical causes of accident, and suggestions to decrease accidents.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.271-275
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• 2015

The floodlighting assists the pilot in taxiing the aircraft into and out of the final parking position and provide lighting suitable for passenger to embark and debark and for personnel to load and unload cargo. It is composed of sodium lamps which is consuming high energy. It needs to develop a dedicated LED lamp to replace the existing lamps. In this paper, We propose a suitable asymmetric angle of LED lamps to avoid a pilot's glare and to meet the standard illumination. For this, we analyze asymmetric angle of sodium lamps which are using in airport and confirm whether the illumination distribution and glare index meet the relating standards by using simulation method. Also, we study the needs of asymmetric characteristics of LED ramp by simulating the LED lamps with and without asymmetric characteristics of ramp respectively. With the simulation result, finally we propose the best asymmetric angle of LED lamp to meet the average illumination standard, and avoid a pilot's glare.

• Journal of Drive and Control
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• v.18 no.3
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• pp.8-15
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• 2021

A rear axle steering (RAS) system is attached to the rear of medium and large commercial vehicles that transport large cargo. The existing RAS systems are driven by electro-hydraulic actuator (EHA), and most commercialized EHAs consist of electric motors, hydraulic pumps, relief valves, prefill valves and cylinders. The prefill valve required for such EHAs is a type of check valve with extremely low cracking pressure that should not allow RAS to have noise or vibration, and the prefill valve prevents system negative pressure as well as unstable operation. Most papers on this topic rely on experiments to predict valve performance, and theoretically detailed modeling of valves or pipelines is performed, but it is very rare to evaluate hydraulic vibration characteristics by analysing everything from hydraulic pumps to valves comprehensively. In this study, we proposed an experimental circuit that can predict the performance of the prefill valve. The study also analysed the pressure-flow pulsation that is transmitted to the valve through the pipeline, and how the transmitted pressure-flow pulsation affects the valve vibration.

• Journal of Ocean Engineering and Technology
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• v.37 no.3
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• pp.99-110
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• 2023

When a fire accident accompanied by an explosion occurs, the surrounding firewalls are affected by impact and thermal loads. Damaged firewalls due to accidental loads may not fully perform their essential function. Therefore, this paper proposes an advanced methodology for evaluating the fire resistance performance of firewalls damaged by explosions. The fragments were assumed to be scattered, and fire occurred as a vehicle exploded in a large compartment of a roll-on/roll-off (RO-RO) vessel. The impact velocity of the fragments was calculated based on the TNT equivalent mass corresponding to the explosion pressure. Damage and thermal-structural response analyses of the firewall were performed using Ansys LS-DYNA code. The fire resistance reduction was analyzed in terms of the temperature difference between fire-exposed and unexposed surfaces, temperature increase rate, and reference temperature arrival time. The degree of damage and the fire resistance performance of the firewalls varied significantly depending on impact loads. When naval ships and RO-RO vessels that carry various explosive substances are designed, it is reasonable to predict that the fire resistance performance will be degraded according to the explosion characteristics of the cargo.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.225-231
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• 2013

Liquefied gas carriers generally transport cargoes of flammable or toxic nature. Since these cargoes may cause an explosion, fire or human casualty, the accommodation spaces, service spaces and control stations of liquefied gas carriers should be so located as to avoid ingress of gas. For this reason, the paragraph 8.2.9 of IGC Code in IMO requires that the height of vent exits should be not less than B/3 or 6 m whichever is greater, above the weather deck and 6 m above the working area and the fore and aft gangway to prevent any concentration of cargo vapor or gas at such spaces. Besides as known, the LNG market has been growing continually, which has led to LNG carriers becoming larger in size. Under this trend, the height of a vent will have to be raised considerably since the height of a vent pipe is generally decided by a breadth of a corresponding vessel. Accordingly, we have initiated an examination to find an alternative method which can be used to determine the safe height of vent masts, instead of the current rule requirement. This paper describes the dispersion characteristics of boil-off gas spouted from a vent mast under cargo tank cool-down conditions in the membrane type LNG carriers.

• Journal of Korea Port Economic Association
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• v.34 no.2
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• pp.83-96
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• 2018

The improvement in logistics competitiveness is the key element of corporate competitiveness in the era of severe competition among companies and high oil prices due to globalization. For this reason, this study analyzed the effect of transportation mode selection factors of Indonesian export companies on the logistic performance in accordance with the logistics environment. The results of the analysis show that only the cargo characteristics, which are the transportation mode selection factor of export companies, had a significant effect on logistics; the services, time, and expenses, on the other hand, had no effect on logistics performances. This result reflects the poor logistic infrastructure of Indonesia. While the export company considers service, time, and expenses when choosing transportation mode, it had no effect on logistic performances due to poor logistic infrastructure. The poor logistic infrastructure of Indonesia has caused a rise in the overall logistic expenses of companies due to excessive transportation time over the transportation distance, unavailability of on-time acceptance and delivery, and increase in the transportation expenses and subsidiary expenses. These are also the factors that decrease the competitiveness of export companies and affect the promotion of the manufacturing industry and foreign investment for the purpose of job creation and industrialization by the Indonesian government. Therefore, the logistics infrastructure must be improved initially. This study determines various points in terms of the logistics infrastructure environment of Indonesia, a developing country, using previous studies and provides their implications.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.539-549
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• 2016

This study analyzed ship's passing characteristics in relation with incoming and outgoing routes in Yeosu Gwangyang Port, and examined the risk factors and measures for safety management of marine traffic. The number of passing ships in Yeosu Gwangyang Port was about 60,000 ships annually based on 2014, and the tonnage rose 73% from 447,000 thousand tons in 2005 to 770,000 thousand tons in 2014. Actually, the number of large passing ships was revealed to enormously increase. As a result of marine traffic survey in Yeosu Gwangyang Port for three days in August 2015, daily average passing ships were 408 ships, and 77% of the total passing ships passed between 04:00 and 20:00. The chemical ships and general cargo ships took up the most at 58% of the total incoming and outgoing ships, followed by other work ships at 21%, tankers at 8%, fishing vessels at 7.5% and container ships at 5.5%. Concerning the size of passing ships, ships less than 1,000 tons accounted for 58.6% of the total passing ships. Ships of 1,000-5,000 tons were 20.1%, and those of 5,000-10,000 tons were 6.8%, and more than 10,000 tons were 14.4%. Especially, ships of 500 tons and less using mainly coastal passing routes took up 49% of the total passing ships. As for ship's passage ratio by route, Nakpo sea area where many routes meet accounted for 27.2%, specified area 49%, costal route 8%, specified area's incoming and outgoing sea area around Daedo 4.5%, and Dolsan coastal ara and Kumhodo sea area 8.5%. The number of ships standing by for anchoring in the six designated anchorages was 230 for three days. The standby rate for anchoring was 25% based on the specified area passing ships. In Nakpo sea area, where many routes meet, parallel passing and cross passing between ships occurred the most frequently. In the specified area, many cases, in which incoming and outgoing cargo ships at the starting and ending parts and incoming and outgoing work ships and fishing vessels at the coastal routes cross, took place. Consequently, the following measures are urgently needed: active passing management in the Nakpo sea area, where passing routes are complex, specified areas and costal traffic routes, the elimination of rocks in the route close to Myodo, an effort to improve routes including shallow depth area dredging, and rational safety management for small work ships frequently incoming and outgoing the passing routes of large ships, and fishing vessels operated in the sea areas around those passing routes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.57-62
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• 2006

Busan New Port, under construction aiming for the hub of Northeast Asia and Partly in operation, had damaged up to 48 billion Won due to Typhoon 'maemi' in 2003. The present criteria of domestic harbor design only describes about the critical wave height with respect to the size of vessel for harbor tranquility. The berth operation ratio which represents the annual available berthing days is depending on the efficiency of cargo handling work and this depends on the motion of the moored vessel due to the wave action and the characteristics of cargo gears. The motion of moored vessel might be related not only to the wave height but also to wave period. Furthermore, the berth operation ratio relies on external forces such as currents and winds, including the characteristics of mooring system and the specification of the moored vessel. In this study we only deal with berth operation ratio in normal sea state, considering wave and current by measured data and numerical calculation. Especially we tried to evaluate the berth operation ratio for each berth adopting the variation of dredging and reclamation plan and the change of wave environment during the process of the new port construction. For better understanding and analysis of wave transformation process, we applied the steady state spectral wave model and extended mild-slope wave model to the related site. This study summarizes comparisons of harbor responses predicted by two numerical predictions obtained at Busan New port site. Field and numerical model analysis was conducted for the original port plan and the final corrected plan.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.264-274
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• 2020

The Ro-Ro ferry ship capsized and sank to the bottom of the sea because of the rapid turning for several reasons, such as lack of stability due to the center of gravity rise from the extension and rebuilding of the stern cabin, excessive cargo loading, and shortage ballast, poor lashing, etc. The purpose of this study was to investigate and analyze the cause of the ship's rapid flooding, capsizing, and sinking accident according to rapid turning scientifically and accurately using the Fluid-Structure Interaction( FSI) analysis technique. Several tests were conducted for this cause investigation of the flooding and sinking accident correctly and objectively, such as the realization of the accurate ship posture tracks according to the accident time using several accident movies and photos, the validation of cargo moving track, and sea water inflow amount through the exterior openings and interior paths compared with the ship's posture according to the accident time using the floating simulation and hydrostatic characteristics program calculation, and the performance of a full-scale ship flooding·sinking simulation.