• 한국해양공학회지
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• 제28권5호
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• pp.387-395
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• 2014

In this paper, a numerical analysis for an internal turret moored vessel located at a 400-m water depth is conducted. The target vessel has an internal turret that is located at the 0.2 Lpp position from the fore-side, with $3{\times}4$ complex mooring lines installed around the turret circumference. To investigate the motion response of the vessel and the structural reliability of the lines, model tests were conducted. The KRISO ocean basin has a water depth of 3.2 m, which represents 192m using a scaling of 1:60. In order to precisely represent the real-scale condition, equivalent mooring lines needed to be designed. Truncated mooring lines were designed to supplement the restriction of the flume's water depth and increase the reliability of the model testing. These truncated mooring lines were composed of two different chains in order to match the pre-tension, simultaneously restoring the curve and variation in the effective line tension. The static similarities were compared using a static pull-out test and free decaying test, and the dynamic similarities were matched via a regular wave test and combined environments test. Consequently, the designed truncated mooring system could represent the prototype mooring system relatively well in the aspects of kinematics and dynamics.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.166-172
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• 2004

An underwater motion measurement system was constructed for applications to the model basin. A commercial motion capture system, FALCON of Motion Analysis Corp., which corrects automatically the distortion caused by refraction of the light passing through water and air, was adopted for underwater motion measurement. The modifications of FALCON system were performed: waterproofing camera housings, markers, connectors, and a new blue ring lighter. the accuracy of the motion measurement was obtained within the calibration error of 0.87mm in average and 0.89mm in standard deviation for the distance of 500mm between two markers on the calibration device. the volume of $2100mm(length)\times2100mm(breadth)\times2300mm(Height)$ was covered with 4 cameras of the underwater motion measurement system. For the performance verification, motion measurement test of a vertical mooring chain model excited at the top end was carried out. The 3D motions of mooring model were measured with variable amplitude and period of the forced excitation. Higher order motions of the mooring model were observed as the excitation period decreases. the performance of the system was verified by successfully measuring 3D motion of mooring model.

• 해양환경안전학회지
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• 제25권3호
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• pp.313-319
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• 2019

As vessels become larger and competition between ports intensifies, there has been an increase in the number of cases where vessels that exceed the available berths are berthed at the pier. Therefore, there has been an increase in the number of cases in which the bow or stern of a ship is projected and moored. The risk of overhanging berthing is that mooring safety can be compromised because it is not possible to connect the bow and stern mooring line to the ship properly. In addition, collision accidents may occur between moving vessels if the view of a vessel moving in the port is obstructed. Therefore, in this study, the simulation of mooring safety was performed according to the overhanging range in Piers No. 6 and 7 in Ulsan's main port to propose the overhanging limit and operational standards according to each ship. As a result of the assessment, 30,000 DWT bulkers are able to overhang up to 0.75B, and 50,000 DWT bulkers can overhang up to 0.50B. The results of this study are expected to be used as basic data for setting the allowable overhang limit, as well as clear usage criteria for safe unloading operations.

• Journal of Advanced Research in Ocean Engineering
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• 제4권3호
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• pp.115-123
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• 2018

This study was carried using the new approach method to design appropriately the Loading Arm length and the alarm setting according to ship movements on Loading and Unloading marine Berth. The quasi-static mooring analysis was performed to estimate 110,000DWT ship's movements based on environmental conditions such as wind, current and wave. The mooring motion of the ship is very important to determine the loading arm scope, and in this case, the operation condition is performed on the ship without considering the damaged condition of the mooring line because the ship movement in case of damage is larger than intact, and all operations are stopped, the loading arm being released due to control system. From the result of mooring analysis, motion displacements, velocities and accelerations were simulated. They were used to simulate the maximum drifting speeds and distances. The maximum drifting speeds were checked to be satisfied within drifting speed limits. The total maximum drifting distances were simulated with alarm steps of the new approach method. Finally, the loading arm envelopes using the total maximum drifting distances were completed. Therefore, it was confirmed that the new approach method for loading arm envelopes and alarm settings was appropriate from the above results. In the future, it will be necessary to perform the further advanced dynamic mooring analysis instead of the quasi-static mooring analysis and to use the precise computer program analysis for various environments and ship movement conditions.

• 한국해양공학회지
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• 제26권2호
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• pp.48-57
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• 2012

This paper deals with numerical analyses in the context of estimations of hydrodynamic motions and dynamic loads for a floating type offshore platform using some exclusive simulation code such as code for the simulation of a floating type of offshore crane based on multi-body dynamics, along with the commercial code AQWA. Verifications of numerical models are carried out by comparing the RAO results from the simulation code. In the verification analyses, hydrodynamic motions are examined in the frequency domain for the floating type offshore platform according to the mooring lines. Both the hydrodynamic motions and dynamic loads are estimated for floating type offshore platforms equipped with the catenary type and taut mooring lines. A review and comparison are carried out for the numerically estimated results. The structural safety of the connection parts in an offshore structure such as a floating type offshore platform is one of the most important design criteria in view of fatigue life. The dynamic loads in the connecting area between a floating type offshore platform and its mooring lines are estimated in detail according to variations in the mechanical properties of the mooring lines. The dynamic tension load on the mooring lines is also estimated.

• 수산해양기술연구
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• 제46권1호
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• pp.20-31
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• 2010

In this research, the submersible fish cage was designed to avoid structural and biological damage during harsh sea conditions. The submersible cage system consists of netting, mooring ropes, a floating collar, floats, sinkers and anchors. Whole elements of the cage were modeled on the mass-spring model. The computer simulations were carried out to investigate the dynamic behavior of the cage and to calculate mooring line tension subjected to tidal currents and waves. As expected, the tension values in the mooring line of the submerged position are 36% less compared to that of the surface cage under the same loading conditions. As the wave was used in combination with the current velocity of 1m/s, the average tensile load for the submerged cage showed 85% of the value for the floating cage. The simulation results provide an improved understanding of the behaviors of the structure and valuable information on the optimized design of the cage system exposed to open ocean environmental factors.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.124-128
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• 2002

본 논문에서는 FPSO 측면에 나란히 연결된 작업선에 대한 계류계 해석이 수행되었다. FPSO 측면에 연결된 작업선의 횡동요에 의한 충돌 가능성, 작업선의 연결선 및 펜더의 파손 가능성 등에 대한 검토가 이루어졌다. 다물체 계류계 해석을 위하여 MOSES 프로그램을 사용하였고, FPSO와 작업선과의 유체역학적 상호작용은 무시하였다.

• 해양환경안전학회지
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• 제29권5호
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• pp.445-455
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• 2023

IPCC에서 발표한 제6차 기후변화 보고서에 따르면 지구온난화에 따른 해수면 상승이 가속화되고 있으며, 2100년 예상 해수면 상승은 저탄소 시나리오(SSP 1~2.6)에서는 47cm, 고탄소 시나리오(SSP 5~8.5)에서는 82cm로 분석되었다. 해수면 상승은 항만 인프라에 심각한 피해를 입히고, 항만 내에 정박 중인 선박의 계류안전성을 저하시킬 수 있다. 본 연구에서는 해수면 상승시 부두에 계류한 선박의 계류안전성 향상 방안을 도출하기 위해 만조시 침수 피해가 잦은 목포항을 선정하여 해수면 상승 시나리오에 따른 실제 접안 선박에 대한 계류 평가 요소의 민감도를 분석하였다. 분석 결과, 해수면이 상승함에 따라 동일한 환경조건에서 계류라인 장력, 계선주 하중, 계류라인 수직각도, 선체 6자유도 운동값이 대체로 증가하는 것으로 분석되었다. 또한, 마루높이가 상향되면 모든 계류 평가 요소의 값이 대체로 감소하여 선박 및 부두의 안전성 향상에 유리한 것으로 분석되었다. 본 연구 결과는 목포항 해수면 상승에 따른 항만 및 선박의 안전성 향상 방안을 확보하기 위한 기초자료로 활용될 수 있을 것이다.

• 수산해양기술연구
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• 제58권1호
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• pp.19-31
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• 2022

Damages by jellyfish are occurring frequently around the world. Among them, accidents caused by jellyfish stings are serious enough to cause death. So we designed a jellyfish blocking net and analyzed its stability to prevent sting caused by jellyfish entering the beach. To this end, the dynamic behavior of the jellyfish blocking net according to the current speed (0.25-1.0 m/s) and the net type (50, 100 and 150 mm) on the upper part of the blocking net was modeled using the mass spring model. As a result of simulations for the model, the horizontal tension (horizontal component of the mooring tension) of the mooring line increased with the decrease in the mesh size on the upper part of the blocking net at all current speeds, but exceeded the holding force at high tides faster than 0.5 m/s and exceeded the holding force at all current speeds at low tide. Therefore, the jellyfish blocking nets showed poor stability overall. The depth of the float line had a little difference according to the upper mesh size and increased lineary proportional to the current speed. However, the float line sank too much to block the incoming jellyfish. These analysis results helped us find ways to improve the stability of the jellyfish blocking net, such as adjusting the length of the mooring line and improving the holding power. Therefore, it is expected that this technology will be applied us various underwater structures to discover the weaknesses of the structures and contribute to increasing the stability in the future.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2019년도 춘계학술대회
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• pp.135-137
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• 2019

최근 액체화물운반선 운송량이 증가함에 따라 국내외에서 해상환적(Ship-to-ship)에 대한 필요성이 대두되고 있다. STS 계류의 경우, 일반적인 부두에서의 계류와 그 특성이 다르기 때문에 다른 기준으로 안전성 검토가 이루어져야 하지만, 국내에서는 별도의 기준이 부재한 상황이다. 따라서 본 연구에서는 STS계류의 특성을 파악하기 위해 상용 수치해석프로그램인 OPTIMOOR 프로그램 이용한 STS 계류 시뮬레이션 및 민감도 분석을 시행하였다. 대상해역은 여수항의 D2 정박지를 모델링하였으며, 대상 선박의 모델링은 VLCC-VLCC의 Case로 선정하였다. 이 수치해석과 민감도 분석을 통하여 STS 계류의 특성을 파악하고자 하였으며 이를 바탕으로 STS 계류안전성 평가에 대한 기준을 확립하고자 하였다. 수치해석 시뮬레이션 결과, STS 계류는 선박 재화상태, 기상상태(파주기 및 파고영향) 및 만남각, 그리고 계류삭의 초기장력 등에 따라 변화함을 확인하였다. 또한 Risk Matrix를 작성하여 해당 해역에서의 안전외력범위를 설정하였다. 이 결과를 통해 STS의 계류 특성을 파악할 수 있으며, 계류안전성 평가 기준을 개정에 기여할 수 있을 것으로 기대한다.