• 한국초전도ㆍ저온공학회논문지
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• 제25권3호
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• pp.49-55
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• 2023

This paper presents the design of a re-liquefaction system as a BOG (boil-off gas) handling process in liquid hydrogen transport vessels. The total capacity of the re-liquefaction system was assumed to be 3 ton/day, with a BOR (boil-off rate) of 0.2 %/day inside the cargo. The re-liquefaction cycle was devised using the He-Brayton Cycle, incorporating considerations of BOG capacity and operational stability. The primary components of the system, such as compressors, expanders, and heat exchangers, were selected to meet domestically available specifications. Case studies were conducted based on the specifications of the components to determine the optimal design parameters for the re-liquefaction system. This encompassed variables such as helium mass flow rate, the number of compressors, compressor inlet pressure and compression ratio, as well as the quantity and composition of expanders. Additionally, an analysis of exergy destruction and exergy efficiency was carried out for the components within the system. Remarkably, while previous design studies of BOG re-liquefaction systems for liquid hydrogen vessels were confined to theoretical and analytical realms, this research distinguishes itself by accounting for practical implementation through equipment and system design.

• 수산해양교육연구
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• 제21권2호
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• pp.291-305
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• 2009

As you known well, Ulsan port is very famous for handling chemical products which occupies about 80% of quantities of all Korean ports. Many ship's operators prefer to handle liquid cargo es at proper anchorages instead of the berth for saving port expenses. Ulsan M-10 anchorage was assigned for handling liquid cargoes, however this anchorage's space is restricted by the oil pipeline which lays under seabed about 400m off from the center of M-10 anchorage, for which we have to consider of the external force and counter force for keeping the safety of anchoring. Where, external force is induced by wind, tidal currents and wave while counter force is induced by holding power of anchor/chain. In this study, author evaluated a method to analyze theoretically the limit of external force condition up to which an anchoring ship can keep her position without dragging, and for which applied to many kinds of combined Ships as mother ship of 50,000 DWT Tanker and 4 sizes of Tanker as alongsided ship.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.308-315
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• 2008

극저온 유체를 운반하는 선박의 화물창은 보통 1차 방벽과 2차 방벽으로 구성되어 있다. 1차 방벽에 소량의 극저온 유체의 누출이 생기더라도, 액밀이 되는 2차 방벽에서 추가적인 극저온 유체의 누출을 방지할 수 있기 때문이다. 그러나 2차 방벽에 추가적인 손상이 생길 경우 유리솜으로 만들어진 Flat Joint를 거쳐 선체내벽까지 극저온 유체에 노출될 가능성이 있게 된다. 본 연구의 관심사는 2차 방벽의 손상 정도에 따라, 그리고 누출되는 극저온 유체의 양에 따라, 내측선체에 얼마나 영향이 미치는가를 알아보는 것이다. 이를 위해 본 연구에서는 극저온 유체를 운반하는 선박의 화물창을 구성하는 2차 방벽에 구멍을 뚫어 Flat Joint 사이로 극저온 유체가 흘러 들어가도록 격자를 생성한 후, CFD 소프트웨어를 이용하여 극저온 유체의 누출에 대한 계산을 수행 하였으며 이를 실험 결과와 비교 분석 하였다. 실험과 계산 결과를 살펴보면, 극저온 유체량에 따라 내측 선체에의 피해를 최소화 할 수 있음을 확인하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.308-315
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• 2008

극저온 유체를 운반하는 선박의 화물창은 보통 1차 방벽과 2차 방벽으로 구성되어 있다. 1차 방벽에 소량의 극저온 유체의 누출이 생기더라도, 액밀이 되는 2차 방벽에서 추가적인 극저온 유체의 누출을 방지할 수 있기 때문이다. 그러나 2차 방벽에 추가적인 손상이 생길 경우 유리솜으로 만들어진 Flat Joint를 거쳐 선체내벽까지 극저온 유체에 노출될 가능성이 있게 된다. 본 연구의 관심사는 2차 방벽의 손상 정도에 따라, 그리고 누출되는 극저온 유체의 양에 따라, 내측선체에 얼마나 영향이 미치는가를 알아보는 것이다. 이를 위해 본 연구에서는 극저온 유체를 운반하는 선박의 화물창을 구성하는 2차 방벽에 구멍을 뚫어 Flat Joint 사이로 극저온 유체가 흘러 들어가도록 격자를 생성한 후, CFD 소프트웨어를 이용하여 극저온 유체의 누출에 대한 계산을 수행 하였으며 이를 실험 결과와 비교 분석 하였다. 실험과 계산 결과를 살펴보면, 극저온 유체량에 따라 내측 선체에의 피해를 최소화 할 수 있음을 확인하였다.

• 한국소음진동공학회논문집
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• 제13권10호
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• pp.791-797
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• 2003

A liquid storage rectangular tank structures are used In many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks In contact with Inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine or propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. In the previous report, we have developed numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present report, using the numerical analysis, vibrations characteristics In deep water tank are investigated and discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1079-1084
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• 2003

A liquid storage rectangular tank structures are used in many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks ill contact with fluid near engine or propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. In the previous report, we have developed numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present report, using the numerical analysis, vibrations characteristics in deep water tank are investigated and discussed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 춘계학술대회논문집
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• pp.145-153
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• 2002

A coastwise chemical tanker sailing at full speed has capsized in calm water and whole turing. In the precious paper, we investigated reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and the vertical distance between the center of gravity of the ship and the renter of lateral water drag.

• 한국항해항만학회지
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• 제43권6호
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• pp.469-474
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• 2019

세계의 주요 자원중 하나인 원유는 산업의 가장 기초적인 부분을 담당하고 있으며 원유를 통하여 많은 액체화물이 생산되고 있다. 석유화학단지들은 인근의 항만을 통해 원유를 수입후 정제를 통해 석유정제품, 화학생산공업품 등을 생산한다. 본 연구에서는 우리나라의 주요 석유화학단지와 인근에 위치한 액체화물 항만 간의 관계를 확인하고자 울산항, 대산항, 여수광양항을 선정하였다. 항만물동량 시계열 데이터를 이용한 분석을 실시하였으며 VAR 모형을 이용하였다. 이를 수행하기 위해 단위근 검정을 실시했으며 Granger 및 Toda-Yamamoto 인과 검정을 통하여 관계를 확인하였다.

• 대한조선학회논문집
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• 제51권2호
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• pp.114-121
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• 2014

Liquefied natural gas(LNG) cargo containment system(CCS) has the primary function of ensuring both adequate structural safety with respect to sloshing load which is defined as a violent behaviour of the liquid contents in CCS due to external forced motions and thermal insulation keeping natural gas below its boiling point. Among different LNG CCS types such as independent B-type and membrane ones, Mark III CCS is considered in this paper to perform its strength assessment. Mark III CCS plate is designed and constructed by stacking various non-metallic engineering materials such as plywood, triplex, reinforced PU foam that are supported by series of mastic upon inner steel hull structure. From the viewpoint of structural analysis, this plated structure is treated as a laminated composite structure showing complex structural behaviour under external load. Advanced finite element models of Mark III CCS plate is generated and used in conjunction with ultimate strength based failure criteria from laminated composite mechanics for the strength assessment. The strength assessment is performed within the initial failure state of Mark III CCS plate. Results provide failure details such as failure locations and loads. Finally obtained results are reviewed using the loads from acceptance criteria suggested by classification.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.62-67
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• 2004

Many ships in voyage experience weight and buoyancy distribution change by various reasons such as change of sea water density and waves, weather condition, and consumption of fuel, provisions, etc . The weight and buoyancy distribution change can bring the ships out of allowable trim, heeling angle. In these case, the ships should adjust trim and heeling angle by shifting of liquid cargo or ballasting, deballasting of ballast tanks for recovery of initial state or for a stable voyage. But, if the adjustment is performed incorrectly, ship's safety such as longitudinal strength, intact stability, propeller immersion, wide visibility, minimum forward draft cannot be secured correctly. So it is required that the adjustment of trim and heeling angle should be planned not by human operators but by optimization computer algorithm. To make an optimized plan to adjust trim and heeling angle guaranteeing the ship's safety and quickness of process, Uk! combined mechanical analysis and optimization algorithm. The candidate algorithms for the study were heuristic algorithm, meta-heuristic algorithm and uninformed searching algorithm. These are widely used in various kinds of optimization problems. Among them, heuristic algorithm $A^\ast$ was chosen for its optimality. The $A^\ast$ algorithm is then applied for the study. Three core elements of $A^\ast$ Algorithm consists of node, operator, evaluation function were modified and redefined. And we analyzed the $A^\ast$ algorithm by considering cooperation with loading instrument installed in most ships. Finally, the algorithm has been applied to tanker ship's various conditions such as Normal Ballast Condition, Homo Design Condition, Alternate Loading Condition, Also the test results are compared and discussed to confirm the efficiency and the usefulness of the methodology developed the system.