• Journal of Ocean Engineering and Technology
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• v.34 no.1
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• pp.19-25
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• 2020

This paper proposes the optimal shape of an LNG fuel tank with a lattice pressure vessel (LPV) design for a tugboat. The LPV is a Type C tank with a design philosophy of "design by analysis," which facilitates greater variability of shape compared with other traditional Type C tanks. Further, compared with conventional cylindrical fuel tanks, the LPV provides better volumetric efficiency. Considering the shape of a fuel tank room, a trapezoidal shape of the LPV is concluded as the most optimal design. This study performs two major analyses of the LPV: structural and heat transfer analyses. First, a design procedure of the LPV based on structural analyses is elaborated. The finite element method is used for the analyses. Furthermore, the results guarantee that the maximum stresses by applied loads do not exceed an allowable stress limitation. Second, the heat transfer analysis of the LPV is conducted. LNG boil-off gas generation is analyzed based on various insulation materials and the degree of acuum.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.462-469
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• 2019

In this study, a motion control problem for the vessels towed by tugboats or towing ships on the sea is considered. The towed vessels, such as barge ships, are used for several purposes. Generally, these vessels have no power propulsion system and are towed using ropes and towing vessel (tugboats). The basic mathematical model of the towed vessel in which three active rudders are attached was introduced from a previous study. Owing to the dependency of the motions of the towed vessel to the towing ship, a method is suggested to cope with the undesirable disturbance and improve the tracking performance. For the simulation study, a model of the towed vessel with a towing ship is made, and necessary physical parameters are identified from the experiment. For the defined and linearized model, a control system is designed, and the control performance is also evaluated. A simulation study is conducted and the effectiveness of the proposed control strategy is verified.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.597-602
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• 2008

T.S. HANBADA has a relatively large hull and superstructures above the water line, so she has much of leeway or turning of bow with the effect of winds. Especially on berthing, unberthing and/or sailing on low speed, these effects take place more significant. Therefore, it was carried out the numerical calculation of the wind force and moments acting on the T.S. HANBADA, and then calculated the leeway angle and counter rudder angle with the relative wind direction and velocity. Also, it was suggested the maximum wind velocity which could be berthed or unberthed used by bow thruster and the tugboat operations in strong winds. These results will be great helpful to the vessels with large superstructures on ship's handling in harbour or tugboat operations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.209-216
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• 2024

Four accidents occurred between 2020 and 2022 after car ferries built according to a coastal passenger ship modernization plan collided with other ships or came into contact with the dock when entering Jeju Port. Accidents primarily occurred owing to careless ship handling and drift by wind during ship handled by herself using bow and stern thrusters without tugboats. Accordingly, in this study, we analyzed the collision accident focusing on car ferry H and the critical wind speed at which the ship cannot be controlled using its own power, tugboat operation plan in increasing wind speed were proposed based on the power required for the ship to berth parallel to the pier without a tugboat considering the external force and moment generated while the ship is berthing. A analysis of the critical wind speed of car ferry H by relative wind direction when using tugboats or not according to the loading status and the berthing speed, showed that one tugboat should be used at the stern when the lateral wind speed is over 10 m/s and two tugboats should be used when the lateral wind speed is over 14m/s berthing at Jeju port.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.157-164
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• 2024

In 2020, 24,000 TEU ultra-large container ships began arriving at the Busan New Port. In this study, the wind pressure and hydraulic force acting on the hull were calculated to obtain the horsepower required for the tugboats for safe berthing and unberthing of a 24,000 TEU ultra-large container ship at the Busan New Port. When the wind speed is 10 m/s (20 kts), 13,000 TEU container ships meet the tug horsepower standard of the current Busan port tugboat operation rules, but 16,000 TEU and 24,000 TEU container ships do not satisfy the regulations. Therefore, it was proposed to raise the standards for tugboat use by dividing the size of ships of "G/T 150,000 tons or more," which is the largest vessel under the current tugboat use standards, into two stages. Because 140,000 tons requires 12,100 horsepower, 170,000 tons requires 14,500 horsepower, and 230,000 tons requires 18,000 horsepower, the study proposed 16,000 horsepower for 150,000 to less than 200,000 tons and 18,000 horsepower for 200,000 tons or more for the use of tugboats.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.383-388
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• 2003

.Ports are usually designed as a dead en port. With an increasing tendency of ship size, the problems such as maneuvering difficulty, turning basin, tugboat fee, etc. are getting to be pointed out. For solving such problem, the conversion of the idea fro dead end port to one-way through port is encourage. To examine the advantage of one-way through port, a quantitative and systematic analyzing procedure is needed. For this, this paper evaluated the preference on the three way of departture using the fuzzy measure and integral model.

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.1
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• pp.60-67
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• 1974

포항종합제철(浦項綜合製鐵)은 제품출하시(製品出荷時) 해송비(海送比)를 약(約) 80% 정도(程度)로 잡고 있으며, 현재(現在) 하루 평균(平均) 약(約) 3,000ton가량의 제품(製品)이 출하(出荷)되고 있다. 따라서 강재품(鋼材品) 수송(輸送)에 push-barge system을 적용(適用)했을 경우에 각(各) 주요예상소비지(主要豫想消費地)의 1일(日) 예상소비량(豫想消費量)을 장래의 시설확장(施設擴張)을 고려(考慮)하여 1,000ton/day에서 4,000ton/day까지 가정하였고 속도(速度)는 연안화물선(沿岸貨物船)의 예(例)를 따라 7knots에서 13knots까지에 걸쳐 조사(調査)하였다. 회항시(廻航時) 화물(貨物)은 일단 없는 것으로 가정하였으며 몇가지 생각될 수 있는 것은 schedule중(中)에서 "1 tugboats: 3 barges", "2 tugboats: 4 barges", "3 tugboats: 5 barges"의 3가지만을 대상(對象)으로 하였다. 조사(調査)한 결과(結果) 소비량(消費量) 1,000ton/day인 경우에 포항-울산(浦項-蔚山) : 1,000 DWT barge, 8 knots, 1 tugboat: 3 barges 포항-부산(浦項-釜山) : 1,550 DWT barge, 8 knots, 1 tugboat : 3 barges 포항-인천(浦項-仁川) : 2,690 DWT barge, 9 knots, 2 tugboats : 4 barges 등이 최적(最適)인 것으로 나타났다. 또 자항화물선(自航貨物船)과 비교(比較)하면 같은 크기의 자항화물선(自航貨物船) $2.5{\sim}3.0$척(隻)에 해당(該當)하는 효율(效率)을 가진다. 이 결과(結果)로 미루어 보건대 push-barge system은 앞으로 연구개발(硏究開發)의 충분(充分)한 가치(價値)가 있는 것으로 생각된다.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.18-22
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• 1999

One of the problem areas in designing a barge is its resistance and corese stability when it is towed by a tugboat. In this paper, as a part of design of a incinerating vessel, the results of some experimental studies on the effect of various kinds of anti-yawing skegs to the course keeping stability and on the additional resistance caused by them were summarized.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.1
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• pp.7-13
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• 2021

In recent years, the importance of environmental regulations is increasing in the shipping industry, and the demands of the industry for this are rapidly increasing. Accordingly, the demand of ship owners is increasing as the shaft generator is a technology that responds to environmental regulations that can be applied to ships the fastest. The shaft generator is a device that can increase the fuel consumption rate of the main propulsion engine by installing an electric motor in the main propulsion engine and using it variably according to the load environment. It operates by the power of the motor at low speeds, and when a sudden load is required, the main propulsion engine and motor operate together, enabling efficient operation. In this paper, the diesel engine and shaft generator of a tug boat are modeled using MATLAB Simulink, and the fuel consumption rate is verified through simulation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.29-37
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• 2021

In the event of a marine pollution accident, Korea, which is bordered by the sea on three sides, would suffer tremendous damage. According to an analysis of marine pollution accidents in Korea, most pollutants were small fishing boats and tugboats. In particular, urgent safety measures are required due to the high incidence of marine pollution accidents caused by stranded tugboats. This study aims to decrease secondary marine pollution accidents by preparing measures to prevent accidents by stranded tugboats, the main source of pollution accidents. To this end an experiment was conducted to mark 63 locations where stranded accidents have occurred on the GPS plotters of 61 tugboats operating in Boryeong sea area. Its effectiveness was then investigated. The result showed that there was no stranded accident by the subject ship during the 20-month experiment period. As a result of survey of the captains, 36 out of 40 respondents (90%) stated that the experiment was significantly helpful in ensuring safe navigation, thus confirming its effectiveness. Various measures were proposed to prevent stranded accidents, including providing information to manufacturers and users by marking the location of grounded accidents on GPS plotters and posting the location information of unknown reefs on the official website of institution Korea Hydrographic and Oceanographic Agency.