• 한국항해항만학회지
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• 제27권2호
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• pp.193-198
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• 2003

일점계류된 선박의 외력에 의한 불안정 거동을 경감시키는 방법에 대하여 검토하였다. 계류된 선박의 수치계산 시뮬레이션을 위해 조종운동방정식을 사용하였고, 선박에 가해지는 외력으로는 풍력과 파강제력이 고려되었다. 파강제력은 3차원특이점분포법에서 얻어진 주파수전달함수로부터 시간영역해석법을 적용하였고, 풍력은 OCIMF(1994)에서 제시한 값을 사용하였다. 계류된 선박의 안전대책으로 바우스러스터를 이용한 제어방법, 두 번째 묘를 이용한 굴레(Birdle)를 씌우는 묘박법이 검토되었다.

• 대한조선학회논문집
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• 제50권1호
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• pp.8-13
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• 2013

Excessive yaw motion of a turret moored vessel was examined in this paper. The vessel was moored by an internal turret and catenary mooring lines. The experiments were conducted in regular waves. Turret moored vessel can oscillate from side to side or move to one particular direction, and eventually exhibit large yaw motion. The results showed that the excessive yaw occured for specific condition, ratio of wave lengths and vessel length. It was found that turret moored floating vessel was unstable for regular wave period from 14 to 18 sec and excessive yaw occurred to maximum 50 deg. The time series, trajectory, phase plot and qualitative analysis are performed. The analysis showed that the results of experiments agreed with the that of analytic method and the excessive yaw could be predicted by the stability analysis.

• 한국수소및신에너지학회논문집
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• 제28권2호
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• pp.212-219
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• 2017

As an environmental pollution and global warming due to an excessive carbon emission are intensified, the importance of renewable energy is in rise today. TCP (Tidal Current Power), one of the renewable energy sources, generates electricity by converting kinetic energy of current into rotational energy of turbine. Also the TCP has a great advantages of predictability and reliability. Because the generating power is proportional to cubic of stream velocity, amplifying current speed by applying duct is highly effective to increase the generating power. SPM (Single Point Mooring) can be applied for the weather vane with various current direction and also augments generating power of the system. In addition, simple installation and retrieval could be a merit of SPM system. By combining duct and SPM, TCP system for relatively low-speed-current and shallow water region can be feasible and economical. In this study, single point moored duct-type TCP system was designed and the motion of submerged structure was investigated in both numerical and experimental method. DNV wadam V4.8-1 and OrcaFlex 10.0a were used for the frequency and time domain motion analysis of system respectively. Duct model scaled by 0.05 of Froude conformity ratio and CWC (Circulate Water Channel) are used for experiment.

• 한국항해항만학회지
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• 제27권1호
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• pp.55-61
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• 2003

계류된 선박의 시뮬레이션을 위해 조종방정식을 사용하였고, 파 중의 선박에 가해지는 파강제력은 3차원 특이점 분포법에서 얻어진 주파수 전달함수로부터 시간영역해석법을 적용하였다. 운동을 유발하는 입사파의 주기와 동일한 선형 파강제력과 성분파 주파수의 차이에 기인하는 장주기 표류력을 외력항에 고려하였다. 규칙파와 불규칙 중에서의 선박의 거동을 비교하여 계류 중 선박에 발생할 수 있는 SLEW MOTION에 불규칙파 및 비선형 파강제력이 미치는 영향을 고찰하였다.

• Journal of Advanced Research in Ocean Engineering
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• 제1권3호
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• pp.176-185
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• 2015

Recently, focus has been placed on ocean energy resources because environmental concerns regarding the exploitation of hydrocarbons are increasing. Tidal current power, one of the ocean energy resources, has great potential worldwide due to its high energy density. The flow velocity is the most crucial factor for the power estimation of TCP(Tidal Current Power) system since the kinetic energy of the flow is proportional to the cube of the flow speed. So sufficient inflow speed to generate electricity from the tidal current power is necessary. A duct system can accelerate the flow velocity, which could expand the applicable area of TCP systems to relatively lower velocity sites. The shapes of the inlet and outlet could affect the flow rate inside the duct. To investigate the performance of the duct, various ducts were preliminary designed considering the entire system that is single-point moored TCP system and a series of simulations were carried out using ANSYS-CFX v13.0 CFD software. This study introduces a ducted turbine system that can be moored to a seabed. A performance estimation and comparison of results with conventional tidal converters were summarized in this paper.

• Ocean Systems Engineering
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• 제11권4호
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• pp.301-312
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• 2021

An optimization framework has been established and applied to a shipshape parametric FPSO hull design. A single point moored (SPM) shipshape floating system suffers a significant level of the roll motion in both the wave frequencies and low wave frequencies, which presents a coupling effect with the horizontal weathervane motion. To guarantee the security of the operating instruments installed onboard, a parametric hull design of an FPSO has been optimized with improved hydrodynamics performance. With the optimized parameters of the various hull stations' longitudinal locations, the optimization through Genetic Algorithms (GAs) has been proven to provide a significantly reduced level of the 1st-order and 2nd-order roll motion. This work presents a meaningful framework as a reference in the process of an SPM shipshape floating system's design.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.244-258
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• 2015

The horizontal stability of a Single-Point Moored (SPM) Floating Liquefied Natural Gas (FLNG) facility is investigated. Both numerical and experimental studies have been conducted for this SPM FLNG. The numerical simulations feature well the experimental data. The effects of the turret locations are studied based on the validated numerical model. Statistic results of the vessel's motions with different turret locations are conducted and compared. The results show that the longitudinal location of the turret has a significant influence on the horizontal stability, which has a strong relationship with the yaw and roll motions. The calculated top tensions on the hawsers also develop a regular change as changing the turret's location. The investigation will provide a brief of principles with more details for the design of the ongoing project.

• 한국항해항만학회지
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• 제42권3호
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• pp.167-176
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• 2018

해상에서 운용되는 일점계류형 해양플랜트의 태양광 발전 시스템은 독립 전원 체계를 가지고 있으며, 해상 환경, 부조일수 등의 영향으로 안정적인 전력을 공급하는 것이 중요하다. 이러한 이유로 태양광 패널을 여러 방향으로 설치하게 되는데, 이 때 각 패널마다 입사되는 광량이 달라지므로 부분음영현상이 발생하게 된다. 육상용 태양광 발전시스템의 발전량은 위도의 영향을 받으므로 우리나라의 경우 $30{\sim}36^{\circ}$ 사이의 각도로 설치하는 것이 일반적이나, 일점계류형 해양플랜트에 설치되는 태양광 발전 시스템의 경우 부분 음영 현상에 의해 최대전력점이 제어 가능 범위 밖에 존재하는 경우가 발생하게 되고 이는 전력 발전 손실이 된다. 이 때 두 패널의 광량차이를 줄임으로써, 최대 전력점을 MPPT 알고리즘이 추종 가능한 범위에 존재하게 하여 발전 효율을 더 높일 수 있으며, 시뮬레이션 결과 설치각도 $20^{\circ}$에서 가장 높은 발전 효율 가짐을 확인하였다.

• 한국유체기계학회 논문집
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• 제17권2호
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• pp.41-47
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• 2014

Experimental results are given for the vertical motion of water in the water chambers for wave energy converter aligned along the wave propagation direction in order to avoid the impulsive wave forces. This paper mainly focuses on the property of the amplitude of the vertical motion of the water surface in the chambers. The amplification has been investigated by dimensionless parameters of wave period to resonance period ratio of the U-shaped oscillation, $T/T_r$, chamber size to wave length ratio, l/L, water depth to wave length ratio, h/L, amplitude of up-down motion of water particles to draft of the front wall ratio, ${\zeta}/D$. It has been shown that l/L should be less than 0.1 and as $T/T_r$ approaches unity the up-down of the water in the chambers is amplified. Also, the structure of the walls which form th water chambers has been examined roughly. It is deduced that the chambers set on both sides of the hull of a single-point moored floating vessel is preferable to those set along a fixed structure such as breakwaters.