• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.140-145
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• 2018

This paper deals with the dynamical analysis of a two-point mooring vessel under surge excitations. The characteristics of nonlinear behaviors are investigated completely including bifurcation and limit cycle according to particular input parameter changes. The strong nonlinearity of the mooring system is mainly caused by linear and cubic terms of restoring force. The numerical simulation is performed based on the fourth order Runge-Kutta algorithm. The bifurcation diagram and several instability phenomena are observed clearly by varying amplitudes as well as frequencies of surge excitations. Stable periodic solutions, called the periodic windows, can be obtained in succession between chaotic clouds of dots in case of frequency ${\omega}=0.4rad/s$. In addition, the chaotic region is unexpectedly increased when external forcing amplitude exceeds 1.0 with the angular frequency of ${\omega}=0.7rad/s$. Compared to the cases for ${\omega}=0.4$, 0.7rad/s, the region of chaotic behavior becomes more fragile than in the case of ${\omega}=1.0rad/s$. Finally, various types of steady states including sub-harmonic motion, limit cycle, and symmetry breaking phenomenon are observed in the two-point mooring system at each parameter value.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.11-17
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• 2014

In this study, a hydraulic model experiment under wave conditions was carried out to investigate the gap/distance between two near-unit farm lines that affects the rope kink and shape variation of a seaweed farm during mooring block movement. As a result, rope kink occurred during the low wave height condition as the gap/distance between the two near-unit farm lines decreased. The seaweed farm maintained a stable shape in the higher wave height conditions as the gap/distance between the two near-unit farm lines increased. This result indicates that rope kink is sensitively affected by the gap/distance between the two near-unit farm lines. A tendency to increase the critical wave height was observed when mooring block movement occurred, and as the mooring block weight and wave period increased. From the experimental results in which incident wave conditions and the mooring block weight changed, as the front side mooring block weight increased from 3.0 to 8.0 tons, the seaweed farm was stable, and rear side mooring block movement hardly occurred. The observed tension of the seaside mooring line was a maximum at about 3.0 ton/m.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.426-431
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• 2016

In quay processes in shipyards, it is difficult to manage workers and to maintain secure working environments because at least 1,000 people can occupy the quay at the same time. In this study, a system was designed to monitor the environment and processes of quay operation. In order to lower initial investments and the costs of maintenance and operation, the entire system consists of six connected components. Considering the communication environment of the shipyard site, Wi-Fi and the LoRa communication protocol were selected for the system. The feasibility of the communication protocols was verified by data transmission tests in the field. The designed system can provide real-time information about employees working in the quay area, the safety status of moored ships on the quay, and step-by-step alarms in dangerous situations based on the detected information. The system is expected to prevent or greatly reduce safety hazards.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.355-358
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• 2011

방충재(fender)는 항만에서 선박의 안전한 접이안, 계류, 안벽 보호를 하기 위하여 설치된 중요한 안벽 시설 중 하나이다. 기존의 고무 방충재는 접안력에 의한 초기 변형 28% 정도에서 가장 높은 반력이 발생하기 때문에 선박과 안벽에 지속적인 힘을 주기 때문에 안벽 및 선체에 손상을 주고 있다. 이는 잔교식이나 중력식 부두에서도 나타나는 현상이다. 또 선체의 용접 비드에 의하여 방충재 훼손으로 보수 유지비가 증가하고 안벽에 앵커로 고정된 고무 펜더는 유연성이 떨어져 선박 충격에 의한 쉽게 떨어지고 패널패드도 탈락된다. 이 연구에서는 초기 반력이 적은 에어 펜더 혹은 폼 펜더를 제안한다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.151-156
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• 2004

최근 국내외에서 국제무역 물량의 증대에 따라 대규모 항만 건설 공사가 진행되고 있으며, 이에 경제성, 시공성이 뛰어난 Caisson 형식의 구조물이 많이 사용되어지고 있다. 특히 항만 및 어항의 외곽시설인 방파제는 계류선박의 안전과 하역 및 적화를 용이하게 하는 중요한 구조물이다. 따라서, 본 연구에서는 Caisson식 방파제에 태풍, 충격력과 같은 몇 가지 외력 조건에 대하여 구조 해석을 실시하여 손상메커니즘을 분석하였다 이러한 손상 메커니즘에 따라 손상을 인위적으로 발생시켜 손상 위치 탐색을 수행하였다.

• Journal of Ocean Engineering and Technology
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• v.32 no.1
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• pp.21-27
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• 2018

The design and analysis of a quayside mooring system for safe mooring of Prelude FLNG under extreme environmental conditions were carried out. The design of the mooring system considered the yard operation conditions and maximum wind speed during a typhoon. In order to secure the mooring safety of Prelude FLNG under an extreme environment, a special steel structure was designed between the quay and Prelude FLNG to maintain the distance from the quay to a certain extent to avoid a collision with the inclined base. The mooring safety was also ensured by installing additional new parts on the quay. A mooring analysis and mooring safety review were performed with more rigorous modeling considering the nonlinearity of the mooring rope and fender. In order to secure additional safety of the mooring system under extreme environmental conditions, a safety assessment was conducted on the failures of the mooring components proposed in the marine mooring guidelines. Based on the results of the mooring analysis, it was confirmed that the Prelude FLNG can be safely moored even under the extreme conditions of typhoons, and a worst case scenario analysis verified that the mooring system design was robust enough. The proposed mooring analysis and design method will provide a basis for the safe mooring of ultra-large floating offshore structures of similar size in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.1-12
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• 2021

The purpose of this paper is to study of the applicability of the current response spectrum analysis method by grasping the dynamic behavior characteristics of soil-pile and pier-crane in pile mooring facilities. To this end, time history analysis was performed using Abaqus as a design variable for various soil types, pile-ground modeling, and structure specific cycles. The results were compared with the analysis results of the response spectrum. Subsequently, a problem has been found in the current response spectrum analysis and the improvements are needed when considering the dynamic behavior of the ground-pile and pier-crane of the pile mooring facility.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.299-301
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• 2012

제주 강정항은 우리나라 남방해역의 보호라는 안보적인 측면과 대형 크루즈선 유치를 통한 관광산업의 활성화를 위해 해군기지와 민항의 기능을 가진 민 군복항으로 건설되고 있다. 본 연구에서는 제주 강정항 계류시설의 대상선박인 15만톤급 초대형 크루즈선의 입 출항 및 통항 안전성 판별을 위해 실시하는 선박조종시뮬레이션의 일반 수행 절차와 선행 연구 등을 분석한다. 이는 선행 연구에서 제기된 주요 쟁점사항들을 명확하게 분석함으로써 객관적이고 신뢰성 높은 선박조종시뮬레이션 연구를 수행하고자 하는 것으로, 주요 검토 사항은 수역시설인 선회장과 진입항로의 교각, 크루즈선의 풍압면적과 적용 풍속 등을 면밀하게 고찰하여 시뮬레이션에 반영하고자 함이다. 또한 제주 강정한 건설은 사회적 관심이 매우 큰 국책사업임을 감안하여 선박조종시뮬레이션 분석 및 평가 등에 해상교통안전 및 선박운용 분야의 전문가그룹을 자문위원으로 구성했고, 연구 결과의 타당성 확보를 위해 해상교통안전진단제도에 명시된 선박조종시뮬레이션 표준절차와 평가 방법 등을 적용하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1036-1043
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• 2022

This paper discusses about the development of a visual sensor that can be installed in an automatic mooring device to detect the berthing condition of a vessel. Despite controlling the ship's speed and confirming its location to prevent accidents while berthing a vessel, ship collision occurs at the pier every year, causing great economic and environmental damage. Therefore, it is important to develop a visual system that can quickly obtain the information on the speed and location of the vessel to ensure safety of the berthing vessel. In this study, a visual sensor was developed to observe a ship through an image while berthing, and to properly check the ship's status according to the surrounding environment. To obtain the adequacy of the visual sensor to be developed, the sensor characteristics were analyzed in terms of information provided from the existing sensors, that is, detection range, real-timeness, accuracy, and precision. Based on these analysis data, we developed a 3D visual module that can acquire information on objects in real time by conducting conceptual designs of LiDAR (Light Detection And Ranging) type 3D visual system, driving mechanism, and position and force controller for motion tilting system. Finally, performance evaluation of the control system and scan speed test were executed, and the effectiveness of the developed system was confirmed through experiments.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.6
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• pp.659-666
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• 2009

Recently, there are several problems in space, contiguity and facility of the existing harbors issued due to the trend of enlarging the container capacity of the large container vessel, the Mobile Harbor has been proposed conceptually as an effective solution for those problems. This concept is a kind of transfer loader of the containers from the large container ship, which is a floating barge with a catamaran type in the underwater part, and so prompt maneuverability and work effectiveness. For the safe mooring of two floating bodies, a container and the mobile harbor, in the near sea apart from the quay, a robot arm mooring facility specially devised would be designed and verified through comparison study under various environmental sea condition in the inner and outer harbor. DP system (Dynamic Positioning System) using the azimuth thruster and a pneumatic fender, etc, will be considered as a next research topic for the mooring security of multi-body floaters.