부이 형상에 따른 부이줄 장력의 차이

이건호 ( Gun Ho Lee ),김인옥 ( In Ok Kim ),차봉진 ( Bong Jin Cha ),정성재 ( Seong Jae Jung ) 한국어업기술학회 2014 수산해양기술연구 Vol.50 No.3

The difference of mooring tension by type of buoy was investigated in the circulating water channel and the wave tank for deducting the most stable buoy from the current and the wave condition. 5 types of buoy made up of short cylinder laid vertically (CL-V), short cylinder laid horizontally (CL-H), capsule (CS), sphere (SP) and long cylinder (CL-L) were used for experiments. A mooring line and a weight were connected with each buoy. A tensile gauge was installed between a mooring line and a weight. All buoy`s mooring tension was measured at the same time for the wave test with periods of 1.5.3.0 sec and wave heights of 0.1.0.3 m, and the current test with flow speeds of 0.2.1.0 m/sec. As a result, the order of tension value in the wave test was CL-H > CL-V > SP > CS > CL-L. In the current test CL-V and CL-H were recorded in the largest tension value, whereas SP has the smallest tension value. So it seems that SP buoy is the most effective in the location affected by fast current. CS is predicted to be suitable for a location that influence of wave is important more than that of current if practical use in the field is considered. And it was found that the difference of mooring tension among buoys in wave is related to the product of the cross sectional area and the drag coefficient for the buoy`s bottom side in high wave height. The factor for the current condition was not found. But it was supposed to be related to complex factors like a dimension and a shape by buoy`s posture to flow.

성공적인 해양부이 계류를 위한 개선 방안

정다운,박준성,송규민 한국해양과학기술원 2021 Ocean and Polar Research Vol.43 No.3

In-situ experiment using ocean buoys is a direct ocean observation and has been playing an important role from the past to the present based on high reliability. The ocean buoy is operated more stable than before due to the technological development of communication (GPS, satellite, …) and equipment, but still moored buoys are not free from various accidents occurring in the ocean. Nevertheless, there is currently a lack of countermeasures or manuals about mooring accidents. Therefore, in this study, based on the experience of operating buoys conducted for many years, the advantages and disadvantages of ocean buoys according to size were analyzed. and legal procedures before and after buoy mooring were presented to enhance the use of buoys. And it is suggested to realize successful experiment by proposing considerations before mooring the buoy in preparation for an accident.

7마일 등명기를 결합한 경량화 등부표의 운동 해석

손보훈,고석원,양재형,정세민 해양환경안전학회 2018 해양환경안전학회지 Vol.24 No.5

현재 운용되고 있는 대형 등부표는 대부분 철소재로 제작되어, 부식과 침식에 취약할 뿐 아니라 중량이 커서 설치 및 유지보수 가 어렵다. 또한, 주위를 항해하는 선박과 충돌시 등부표 및 선박의 구조적 피해는 물론 인명피해를 발생시키기도 한다. 이러한 철소재 등 부표의 문제점들을 해결하고자 친환경, 경량화 재질을 사용한 등부표가 주목을 받고 있고, 최근 국내에서도 부체와 상부구조물에 각각 친환경 경량소재인 EPP(Expanded Polypropylene)와 알루미늄 소재를 적용한 경량 등부표가 개발된 바 있다. 등부표가 본연의 기능을 수행하기 위해서는 복원성능 및 파랑중 (동적) 운동성능의 확보가 중요한데, 경량화 등부표는 기존의 철재 등부표와 중량 분포 및 운동특성이 다르기 때문에 이에 관한 연구가 필요하다. 본 연구에서는 새롭게 개발된 전원일체형 경량 7마일 등부표의 복원성능과 다양한 환경조건(파도, 바람, 조류)하에서의 운동성능을 평가하였다. 계류시스템을 고려한 운동해석에는 ANSYS사의 AQWA를 사용하였으며, 운동성능 추정의 정도 향상을 위하여 상용 CFD SW인 Simens사의 STAR-CCM+를 사용해 추정한 풍하중 및 조류하중을 운동해석에 사용하였다. 추정된 등부표의 유의운동의 최대값을 비교한 결과, 바람보다는 파도와 조류가 운동성능에 상대적으로 큰 영향을 미치며, 해상상태가 나빠질수록 (Beaufort No. 3이상) 운동이 급격히 커지는 것으로 예측되었다. 이는 해상상태가 나빠지면서 불규칙 파 에너지 스펙트럼의 최대 주파수가 등부표의 고유주파수에 근접하기 때문으로 추정된다. Because large buoys are mainly made of steel, they are heavy and vulnerable to corrosion by sea water. This makes buoy installation and maintenance difficult. Moreover, vessel collision accidents with buoys and damage to vessels due to the material of buoys (e.g., steel) are reported every year. Recently, light buoys adopting eco-friendly and lightweight materials have come into the spotlight in order to solve the previously-mentioned problems. In Korea, a new lightweight buoy with a 7-Nautical Mile lantern adopting expanded polypropylene (EPP) and aluminum to create a buoyant body and tower structure, respectively, was developed in 2017. When these light buoys are operated in the ocean, the visibility and angle of light from the lantern installed on the light buoys changes, which may cause them to function improperly. Therefore, research on the performance of light buoys is needed since the weight distribution and motion characteristics of these new buoys differ from conventional models. In this study, stability estimation and motion analyses for newly-developed buoys under various environmental conditions considering a mooring line were carried out using ANSYS AQWA. Numerical simulations for the estimation of wind and current loads were performed using commercial CFD software, Siemens STAR-CCM+, to increase the accuracy of motion analysis. By comparing the estimated maximum significant motions of the light buoys, it was found that waves and currents were more influential in the motion of the buoys. And, the estimated motions of the buoys became larger as the sea state became worser, which might be the reason that the peak frequencies of the wave spectra got closer to those of the buoys.

부이형 수중감시 시스템에서 계류라인의 구조 설계

변양헌(Yang-Hun Byun),최범규(Bum-Kyu Choi),오태원(Tae-Won Oh) 한국정보기술학회 2018 한국정보기술학회논문지 Vol.16 No.12

The buoy-enabled underwater surveillance system is a device that is installed in a particular sea area and operated for a certain period of tine and moved to another sea area after recovery. In this paper, a mooring method which is applied for a buoy-enabled underwater surveillance system was selected to maintain installation and enure stable operation. Also, the structure of the mooring line was designed. Two-point mooring method was selected considering interference with the communication cable of array-assembly. The composite structure of buoy chain, nylon rope, and anchor chain is designed as the basic component of mooring line. For the verification of design, a numerical simulation and wave tank experiment were performed. Their results were confirmed similarity in test condition. Finally, the mooring lines were designed for the environment of the sea trial location. The mooring line produced by the final design confirmed the stability above the significant wave height considered in the design on the sea trial.

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine

Hong, Sinpyo,Lee, Inwon,Park, Seong Hyeon,Lee, Cheolmin,Chun, Ho-Hwan,Lim, Hee Chang The Society of Naval Architects of Korea 2015 International Journal of Naval Architecture and Oc Vol.7 No.3

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine is presented. The effects of the Center of Gravity (COG), mooring line spring constant, and fairlead location on the turbine's motion in response to regular waves are investigated. Experimental results show that for a typical mooring system of a SPAR buoy-type Floating Offshore Wind Turbine (FOWT), the effect of mooring systems on the dynamics of the turbine can be considered negligible. However, the pitch decreases notably as the COG increases. The COG and spring constant of the mooring line have a negligible effect on the fairlead displacement. Numerical simulation and sensitivity analysis show that the wind turbine motion and its sensitivity to changes in the mooring system and COG are very large near resonant frequencies. The test results can be used to validate numerical simulation tools for FOWTs.

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine

홍신표,이인원,박성현,이철민,전호환,임희창 대한조선학회 2015 International Journal of Naval Architecture and Oc Vol.7 No.3

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine is presented. The effects of the Center of Gravity (COG), mooring line spring constant, and fairlead location on the turbine’s motion in response to regular waves are investigated. Experimental results show that for a typical mooring system of a SPAR buoy-type Floating Offshore Wind Turbine (FOWT), the effect of mooring systems on the dynamics of the turbine can be considered negligible. However, the pitch decreases notably as the COG increases. The COG and spring constant of the mooring line have a negligible effect on the fairlead displacement. Numerical simulation and sensitivity analysis show that the wind turbine motion and its sensitivity to changes in the mooring system and COG are very large near resonant frequencies. The test results can be used to validate numerical simulation tools for FOWTs.

Coupled CFD-FEM simulation of hydrodynamic responses of a CALM buoy

Gu, Haoyuan,Chen, Hamn-Ching,Zhao, Linyue Techno-Press 2019 Ocean systems engineering Vol.9 No.1

In this paper, the Finite-Analytic Navier-Stokes (FANS) code is coupled with an in-house finite-element code to study the dynamic interaction between a floating buoy and its mooring system. Hydrodynamic loads on the buoy are predicted with the FANS module, in which Large Eddy Simulation (LES) is used as the turbulence model. The mooring lines are modeled based on a slender body theory. Their dynamic responses are simulated with a nonlinear finite element module, MOORING3D. The two modules are coupled by transferring the forces and displacements of the buoy and its mooring system at their connections through an interface module. A free-decay model test was used to calibrate the coupled method. In addition, to investigate the capability of the present coupled method, numerical simulations of two degree-of-freedom vortex-induced motion of a CALM buoy in uniform currents were performed. With the study it can be verified that accurate predictions of the motion responses and tension responses of the CALM buoy system can be made with the coupling CFD-FEM method.

파랑관측부이의 성능예측을 위한 수치해석:동적해석(규칙파)

전인식(Insik Chun),민인기(In-Ki Min),민용침(Yongchim Min),오병철(Byungcheol Oh),심재설(Jaeseol Shim) 한국연안방재학회 2021 한국연안방재학회지 Vol.8 No.3

The prediction of the performance of a wave observation buoy is very important to acquire both in-situ security and good observation quality. In the present study, a numerical method was set up to analyze the dynamic interaction of a spherical buoy with its single point mooring line subject to regular wave conditions. The method was applied to the condition of an existing hydraulic experiment, producing results that are well compatible with experimental results within the limited accuracy of the available data. It was argued that some discrepancies between the numerical and experimental results might be due to the uncertainties of the wave exciting forces acting on the buoy and the experimental conditions of mooring line. The method was finally applied to demonstrate two practical issues related to in-situ wave height measurements; the effect of buoy size on resulting heave motion and the aspect of the numerical integration of heave acceleration to get wave profile.

해양관측용 부이의 설계 건전성 평가 - Part Ⅱ : 계류시스템 구조건전성 평가

금동민(Dong-Min Keum),김태우(Tae-Woo Kim),한대석(Dae-Suk Han),이원부(Won-Boo Lee),이제명(Jae-Myung Lee) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.1

The purpose of the present study was to evaluate the safety under extreme environmental conditions and the dynamic safety under service environment conditions, of oceanographic buoy mooring systems consisting of a variety of material, including chain, wire rope, nylon rope, and polypropylene rope. For the static safety assessment of a mooring system, after the calculation of external forces and the division of a mooring system into finite elements, the numerical integral was conducted to yield the elemental static tension until satisfying the geometrical convergence condition. To evaluate the dynamic safety, various processes were considered, including data collection about the anticipated areas for mooring, a determination of the parameters for the interpretation, the interpretation of tze dynamic characteristics based on an analytic equation that takes into account the heave motion effect of a buoy hull and a mooring system, and a fatigue analysis of tze linear cumulative damage. Based on the analysis results, a supplementary proposal for a wire rope that has a fracture in an actual mooring area was established.

열대 태평양에서 운영되는 TRITON 부이와 비교를 통한 KORDI 부이 시스템 개선 연구

김동국,전동철,김응,황근춘,황상철 한국해양과학기술원 2011 Ocean and Polar Research Vol.33 No.3

This study documents KORDI's experience of successfully deploying a deep ocean buoy for monitoring oceanic and atmospheric variabilities in the tropical western Pacific Ocea nsince May 2010. The primary focus of this study was to compare TRITON (big and old type) with m-TRITON (smaller and new type) buoys within the JAMSTEC's buoy management system. The objective of operating a KORDI buoy is to ascertain oceanic variability in the tropical western Pacific. We adopted a slack-line mooring type to observe water temperatures at six layers from surface to 400 m depth. However, we could not acquire satisfactory results due to lack of expertise in buoy management system. A new KORDI buoy has been developing, which has been modified from both buoys, and ARGOS-3 satellite system and a slack-type mooring line.