• 한국해양공학회지
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• 제29권2호
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• pp.135-142
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• 2015

The float over method is the most preferred method for installing heavy topside onto a jacket platform. A very complex platform with multiple jacket structures on a specific field requires multiple installation procedures. This study validated the installation of two topsides using a single installation barge to reduce the operation and installation cost. The hydrodynamic properties of the installation barge during the installation of two topsides were calculated. The tension and fender forces during docking were investigated to show the validity of the proposed dual topside installation method. In conclusion, the operational safety of the proposed procedure was validated through the calculation of the motion of the installation vessel and loads on the jacket legs.

• 대한조선학회지
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• 제21권3호
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• pp.43-50
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• 1984

A body form, which experiences minimum vertical wave-exciting forces in the vicinity of a prescribed wave frequency in water of finite depth, is obtained by an approximate method. Its configuration has the symmetry with respect to the vertical axis, expressed in terms of exponential functions. By distributing three-dimensional pulsating sources and dipoles on the immersed surface of the body, a velocity potential is determined and subsequently hydrodynamic forces including the 2nd-order time-mean drift forces are calculated. The dynamic behavior of the body moored in irregular waves is investigated numerically by using central difference method. Hereby irregular wave trains are simulated with examining its repeatability by comparing the resulting spectrum with original one. Numerical results indicated that the body form obtained from the present analysis possesses in general a favorable hydrodynamic characteristics in comparison with a spherical buoy and that the maximum excursion of the body can be significantly reduced by setting pre-tension of an appropriate amount in the mooring cable.

• Journal of Ship and Ocean Technology
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• 제12권4호
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• pp.1-6
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• 2008

Nowadays, the computational capability and graphical power based on PCs increase very rapidly every year. As a result, the complicated engineering or scientific problems that could have only been handled by supercomputers a couple of decades ago can now be routinely run on PCs. Besides, the PCs can be assembled in parallel to increase its computational capability theoretically without limitation. The Web-based interface and communication tools are also being enhanced very rapidly and the real-time distance learning (E-Learning) and project cooperation on web get increasing attention. Using the-state-of-the-art computational method, a number of complicated and computationally intensive problems are being solved by PCs. The results can be well demonstrated on screen by graphics and animation tools. Those examples include the simulations of fully nonlinear waves, their interactions with floating bodies, global-motion analysis of multi-unit floating production system including complicated mooring lines and risers. Several examples will be presented in this regard. Also, Web and java-applet based educational tools have been developed at Texas A&M University for better understanding of waves and wave-body interactions. The background and examples of such Web-based educational tools published in Kim et al. (2003) are briefly introduced here.

• 대한조선학회논문집
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• 제39권4호
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• pp.24-31
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• 2002

계류된 FPSO와 DP로 위치를 유지하는 셔틀탱커에 있어 장주기 표류운동의 특성은 매우 중요하다. 장주기 공진 운동 해석에 있어 표류감쇠력의 중요성은 아무리 강조해도 지나침이 없으나 감쇠력 발생의 원인이 너무도 다양하기 때문에 아직까지 이론에 의해 정확한 감쇠력을 추정하기가 어렵다. 따라서 모형시험을 통한 표류감쇠력을 이용하는 것이 시뮬레이션에서 장주기 운동예측치의 신뢰성을 높이는 방법이다. 본 논문에서는 FPSO, 셔틀탱커 등의 표류감쇠력의 실험 예측치를 구하기 위해 탱커 선형의 장주기 표류운동 감쇠력을 계측하였다. 파도, 바람, 조류 등에 의한 영향을 살펴보았으며 추진기 작동유무에 따른 장주기 운동감쇠력의 변화를 고찰하였다.

• 수산해양교육연구
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• 제28권2호
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• pp.456-464
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• 2016

NCS development for construction of marine terminal structure was carried out through following procedures such as analysis on characteristics, analysis on duty, development of the first draft for standards, validation of industry sites, duty competency standards through expert committee, and utilizing package. The results were as follows. Firstly, duty competency was classified as levels from 3 to 7. Educational training institutions were followed by 22 universities, 21 colleges, 16 graduate schools, and 10 high schools. Secondly, developed standards were consisted of duty and competency unit. The name of duty was construction of marine terminal structure and competency units were consisted of 9 items as survey on economic effect, evaluation of conditions on construction environment, plan for construction of structure, construction of transfer, mooring, and power equipment, and construction, startup test, and maintenance of terminal structure. 33 competency unit elements below 9 competency units were developed. Thirdly, utilizing package was developed into 3 areas of life-long career path, training criteria, and guidelines for exam according to national competency standards for in order to develop development of labor's career and perform personal management such as hiring and promotion in industry sites.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.121-127
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• 2003

Wave overtopping is one of the most important hydraulic responses of breakwater because it significantly affects its functional efficiency, the safety of transit and mooring on the rear side, wave transmission in the sheltered area, rear side armor stones and to some extent, the structural safety itself. In this study, hydraulic model tests has been carried out to investigate the influence of berm's size on overtopping rate by maximum overtopping rate and mean overtopping rate. The hydrodynamic characteristics of berm breakwater by the overtopping rate can be summarized as follows: 1. It is better to use maximum overtopping rate than to use mean overtopping rate for design of coastal structures in the point of view of stability. 2. When construct berm to decrease energy of waves that it was needed to make breaking conditions of wave on the berm. 3. Under the relative length of berm was over 0.13 overtopping rate was significantly decreased. 4. Overtopping rate affected significantly by the relative length of yhe berm than height of the berm.

• 대한조선학회지
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• 제24권2호
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• pp.29-35
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• 1987

As offshore activities move into deeper ocean, conventional fixed-base platforms drastically increase in size and cost, One of alternatives available is a guyed tower, in which environmental loads are supported by guylines instead of structural members. The guying system of the guyed tower is designed on one hand to be stiff enough to limit the structural displacement in normal operations, but on the other hand to be soft enough to permit large slow sways during the presence of design-level storms. This compliancy provides an efficient means of withstanding harsh environment so that the disproportionate increase in size of deep water platforms can be kept to a rational limit. Novel configurations contain always some degrees of potential risks mainly due to the lack of experience. The most critical hazard inherent to a guyed tower may be the pullout of anchor piles. Once it happens, the guyline fails to function and it may eventually lead to the total collapse of the system. It is the aim of this paper to discuss and quantify the anchor-pullout risk of a guyed tower. A stochastic analysis is made for evaluating the first-upcrossing probability of the tension acting on anchor piles over the uplift capacity. Nonlinearities involved in the mooring stiffness and hydrodynamics are taken into account by using time-domain analysis. A simplified two dimensional dynamic model is developed to exemplify the underlying concept. Real hurricane data in the Gulf of Mexico spanning over 70 years are incorporated in a numerical example of which result clearly indicates highly potential risk of anchor pullout.

• Geomechanics and Engineering
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• 제17권2호
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• pp.165-173
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• 2019

Plate anchors are generally used for structures like transmission towers, mooring systems etc. where the uplift and lateral forces are expected to be predominant. The capacity of anchor plate can be increased by the use of geosynthetics without altering the size of plates. Numerical simulations have been carried out on three different sizes of square anchor plates. A single layer geosynthetic has been used as reinforcement in the analysis and placed at three different positions from the plate. The effects of various parameters like embedment ratio, position of reinforcement, width of reinforcement, frequency and loading amplitude on the pull out capacity have been presented in this study. The load-displacement behaviour of anchors for various embedment ratios with and without reinforcement has been also observed. The pull out load, corresponding to a displacement equal to each of the considered maximum amplitudes of a given frequency, has been expressed in terms of a dimensionless breakout factor. The pull out load for all anchors has been found to increase by more than 100% with embedment ratio varying from 1 to 6. Finally a semi empirical formulation for breakout factor for square anchors in reinforced soil has also been proposed by carrying out regression analysis on the data obtained from numerical simulations.

• 한국항공운항학회지
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• 제26권4호
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• pp.1-12
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• 2018

Baggage Handling System(BHS) is an important element of ground operation services and the importance is further emphasized as air demand increases and passengers change. If there is a problem with departure baggage handling, the aircraft's gate occupancy time will be longer than the initial plan, resulting in congestion of the anchorage leading to final passenger terminal and mooring and road congestion and arrival or It is delayed until the processing of the baggage of the connecting flight and it can cause an economic loss such as confusion in the operation of the airport. The purpose of this study is to investigate the effect of the perception of service quality of BHS users on public Institutions performance through user satisfaction, user performance, and user loyalty. Analysis results using Structural Equation Model was suggested and its implication was discussed in the conclusion.

• Ocean Systems Engineering
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• 제9권3호
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• pp.219-240
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• 2019

This paper presents the comparison between SFT response with linear and nonlinear cables. The dynamic response analysis of submerged floating tunnel (SFT) is presented computationally with linear and nonlinear tension legs cables. The analysis is performed computationally for two wave directions one at 90 degrees (perpendicular) to tunnel and other at 45 degrees to the tunnel. The tension legs or cables are assumed as linear and non- linear and the analysis is also performed by assuming one tension leg or cable is failed. The Response Amplitude Operators (RAO's) are computed for first order waves, second order waves for both failure and non-failure case of cables. For first order waves- the SFT response is higher for sway and heave degree of freedom with nonlinear cables as compared with linear cables. For second order waves the SFT response in sway degree of freedom is bit higher response with linear cables as compared with nonlinear cables and the SFT in heave degree of freedom has higher response at low time periods with nonlinear cables as compared with linear cables. For irregular waves the power spectral densities (PSD's) has been computed for sway and heave degrees of freedom, at $45^0$ wave direction PSD's are higher with linear cables as compared with nonlinear cables and at $90^0$ wave direction the PSD's are higher with non-linear cables. The mooring force responses are also computed in y and z directions for linear and nonlinear cables.